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FATE OF THE FRAGRANCE MATERIAL ACETYL
CEDRENE IN SEDIMENTS INHABITED BY THE BENTHIC
MOLLUSCS MACOMA BALTHICA AND MYA ARENARIA
Kaushal BARAL**, Valentina BURDUKOVSKA*,
Minodora DAVID*, Mads KÆRHUS OLUFSEN*
Bachelor project*/Semester project**
Spring 2013
Supervisor: Prof. Henriette SELCK
Dept. ENSPAC
Roskilde University
Denmark
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Cover picture:
a) Balanidae, b) Mytilus edulis, c) Lanice conchilega, d) Lagis koreni, e) Littorina littorea,
f) Ensis americanus, g) Cerastoderma edule, h) Scrobicularia plana, i) Mya arenaria,
k) Arenicola marina, l) Hediste diversicolor, m) Macoma balthica.
(image source: Senckenberg: World of Biodiversity)
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ACKNOWLEDGEMENT
We would like to express our gratitude for all those who helped us in realizing this project.
Firstly, we would like to thank Lina Dai for providing the basis for our report and guiding us
throughout the process. We would also like to thank prof. Gary Banta, ENSPAC for helping
us identify and acclimatize the test organisms, and the technicians Anne-Grete Winding,
Klara Jensen, May-Britt Kary, for helping in the field work and getting us acquainted with the
laboratory equipment.
Last, but not least, we would like to thank our supervisor, prof. Henriette Selck, for all her
dedication and advice.
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ABSTRACT
In recent time it has come to concern that hydrophobic organic compounds, from the
relatively large group of fragrance materials, enter the aquatic environment via drainage
systems and bioaccumulate in the sediment and biota. Acetyl cedrene is one of these
compounds. In this report the fate and effects of acetyl cedrene were studied on two species of
marine molluscs – Macoma balthica and Mya arenaria – with different feeding strategies. An
experiment was conducted over a period of 14 days, after which the concentrations of acetyl
cedrene present in different compartments (sediment, water, and tissue) were analyzed with a
GC-MS machine. The results were statistically tested with a General Linear Model and a One-
Way ANOVA. The outcome suggested that the actual organisms were not efficient enough in
biotransforming the fragrance material. Additionally, the effects of acetyl cedrene on the
studied species were expressed as a delay in burrowing behavior. Mortality has been recorded
among the test organisms, but it was not a result of the presence of acetyl cedrene.
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TABLE OF CONTENTS%
1."INTRODUCTION".............................................................................................................."6%
1.1"AIM"OF"REPORT"....................................................................................................................."7%
1.2"HYPOTHESIS"..........................................................................................................................."7%
2."ACETYL"CEDRENE"............................................................................................................"8%
2.1"PHYSICAL"AND"CHEMICAL"PROPERTIES".................................................................................."8%
2.2"ROUTES"OF"ENTERING"THE"ECOSYSTEM"................................................................................."9%
2.3"UPTAKE"ROUTES"BY"AQUATIC"ORGANISMS"............................................................................"9%
3."CHOICE"OF"TEST"ORGANISMS"......................................................................................."11%
3.1"MYA"ARENARIA"..................................................................................................................."11%
3.2"MACOMA"BALTHICA"............................................................................................................"12%
4."BIOACCUMULATION"AND"BIOTRANSFORMATION"........................................................"13%
4.1"BIOAVAILABILITY"................................................................................................................."13%
4.2"BIOTRANSFORMATION"........................................................................................................"15%
5."MATERIALS"AND"METHODS".........................................................................................."16%
5.1"SEDIMENT:"COLLECTION"AND"HANDLING"............................................................................."16%
5.2"SEDIMENT"SPIKING"WITH"ACETYL"CEDRENE"........................................................................."17%
5.3"TEST"ORGANISMS:"COLLECTION"AND"HANDLING".................................................................."19%
5.4"EXPERIMENT"SETFUP"............................................................................................................"20%
5.5."BURROWING"BEHAVIOR"....................................................................................................."22%
5.6"WATER,"TISSUE,"AND"SEDIMENT"ANALYSIS".........................................................................."22%
5.7"GCFMS"ANALYSIS".................................................................................................................."27%
5.8"STATISTICAL"METHODS"........................................................................................................"30%
6."RESULTS"......................................................................................................................."31%
6.1"EFFECTS"ON"ORGANISMS"....................................................................................................."31%
6.2"FATE"OF"AC".........................................................................................................................."36%
7."DISCUSSION"................................................................................................................."40%
7.1"EFFECTS"OF"ACETYL"CEDRENE"..............................................................................................."40%
7.2"FATE"OF"ACETYL"CEDRENE"...................................................................................................."43%
8."CONCLUSION"................................................................................................................"44%
9."APPENDICES"................................................................................................................."45%
9.1"APPENDIX"A"–"dw:ww"measurements".................................................................................."45%
9.2"APPENDIX"B"–"Burrowing"behavior"exhibited"over"a"14Fday"period"......................................"46%
9.3"APPENDIX"C"–"Water"volume"in"samples"(from"overlaying"water)"........................................"47%
9.4"APPENDIX"D"F"Laboratory"Techniques:"The"ASE"Machine:"Accelerated"Solvent"Extractor"......"48%
9.5"APPENDIX"E"F"Sample"preparation"for"ASE"............................................................................"50%
9.6"APPENDIX"F"F"Laboratory"Techniques:"The"GCFMS"Machine".................................................."51%
9.7"Appendix"G"–"Overall"results"................................................................................................"53%
10."REFERENCE"LIST".........................................................................................................."54%
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1. INTRODUCTION
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Fragrance materials (FM), such as acetyl cedrene (AC), represent a large group of aromatic
compounds with varying toxicities that can be normally found in household care products.
They have been found both in the water and sediment compartments of wastewater, in the
final stages of wastewater treatment (Simonich et. al., 2000). It is especially the lipophilic
organic compounds that can pose a threat to benthic invertebrates because of their tendency to
bioaccumulate in sediment. These hydrophobic contaminants bind to the sediment particles
and can be taken up by deposit-feeding organisms that thrive on organic matter. So far, traces
of FMs have been found in clams, mussels, fish, sharks, and other marine animals (Kannan et.
al., 2005).
Even though little is known about the toxicity of acetyl cedrene in the aquatic environment, it
has been found to have a measurable concentration in sewage wastewater, it is highly
accumulative in the sediment and has low water solubility (Simonich et. al., 2000). For these
reasons, AC was chosen as the test compound of this report.
The overall aim of the report is to assess the fate and effects of the sediment-bound fragrance
material acetyl cedrene (AC) in the presence of the deposit-feeding mollusc Macoma balthica
and the suspension-feeding mollusc Mya arenaria. The above-mentioned species were
selected because of their high abundance in the local estuarine systems (Isefjord, Roskilde
Fjord, Denmark), and their reported capability of bioaccumulating and biotransforming other
organic pollutants (e.g. PAHs)(Rust et. al., 2004).
Microbial degradation has also been used as a reference point to see to what extent AC is
biodegraded in the absence of macrofauna. In order to do so, an experiment was set-up, and
burrowing behaviour and AC degradation were used as indicators of the fate and effects of the
contaminant. The article written by Dai et. al. (2012) was used as a point of departure for
methods and experimental set-up.
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1.1 AIM OF REPORT
In order to assess the fate and effects of the fragrance material acetyl cedrene, the following
questions were addressed:
1) Does the presence of Macoma balthica and Mya arenaria affect the fate of sediment-
associated AC? And if so, in what way is the fate of AC affected and which organism has the
greater impact?
2) How does the sediment-associated AC affect the studied organisms?
1.2 HYPOTHESIS
Before commencing the experiment, there were several aspects that were hypothesized on.
Firstly, it was presumed that Macoma would show a greater impact on the fate of AC, because
of its feeding strategy (deposit-feeder), compared to Mya, which was expected to have little
impact (suspension-feeder).
Secondly, it was presumed that no AC would be present in the water phase of the experiment
- because of the low water solubility and sediment-binding properties of AC.
And lastly, it was hypothesized that there will be a difference between the concentration of
AC in the sediment measured at the beginning of the exposure period (T0) and the one
measured at the end (Tend) (HA – AC conc. T0≠ AC conc. Tend), in other words, that the test
organisms would affect the fate of AC by diminishing its concentration.
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2. ACETYL CEDRENE
2.1 PHYSICAL AND CHEMICAL PROPERTIES
Acetyl cedrene (AC) is an organic compound widely used as a fragrance material (FM). FMs
are aromatic compounds that are added to care products to give a pleasing scent. They can be
characterized by the presence of aromatic rings and their volatility. These organic materials
can be extracted from nature (plants, trees) or synthesized in the laboratory. The latter are
extracted in the form of oils, concentrates or waxes by processes such as distillation, solvent
extraction. Fragrance materials are usually synthetically derived as the alternative to
macrocyclic compounds found in nature, which are relatively inexpensive compared to their
natural counterparts (Rimkus, 1999). Because of the diversity of the physical and chemical
characteristics of FMs, their ecotoxicity is variable, and their biodegradation rates can range
from readily biodegradable to non-biodegradable (Simonich et al, 2000). Acetyl cedrene has
similar chemical and physical characteristics to HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-
hexamethylcyclopenta-γ-2-benzopyran) and AHTN (7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-
tetrahydronaphthalene), synthetic musk fragrances recognized as significant contaminants of
the aquatic environment, because of their lipophilic properties and persistent nature that has a
tendency to bioaccumulate in fish and other organisms (Rimkus, 1999). AC tends to
accumulate in sediment due to its high octanol-water partition coefficient (Log KOW=5.6–5.9)
and low water solubility (1.28mg/L)(Simonich et al, 2000).
Table. 1 General characteristics of acetyl cedrene
Acetyl Cedrene (CAS 32388-55-9)
Molecular Formula: C17H26O
Octanol-Water Partition Coefficient (Log Kow): 5.6 - 5.9
Water solubility: 1.28 mg/L
Vapor pressure: 0.058 Pa
Boiling point: 272 °C
Table 1 presents some additional information about the general properties of acetyl cedrene.
Data related to the toxic or persistent nature of AC is scarcely available, thus more insight is
needed concerning the fate and effects of this chemical in the aquatic environment.
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2.2 ROUTES OF ENTERING THE ECOSYSTEM
When it comes to the chemicals found in household products, the main route of entering the
ecosystem is by means of sewage water. The quality of sewage water that ends up in surface
waters is closely linked to the raw sewage received, as well as the treatment applied (Benn &
McAuliffe, 1975).
Acetyl cedrene has been detected in the environment under varying concentrations. It has
been found in concentrations of 7.15"±"4.32µg/L in European wastewater influents and
4.97"±"2.27µg/L in US wastewater influents, and in between 0.071- 0.270µg/L in several
German wastewater effluents (Klaschka et. al., 2013; Simonich et. al, 2002).
AC has also been found in biota, with concentrations ranging from <10–93µg/kg fresh weight
in carp muscle tissue (Klaschka et. al., 2013).
2.3 UPTAKE ROUTES BY AQUATIC ORGANISMS
There are multiple ways through which pollutants can enter an organism. For our test
organisms the most relevant uptake routes are via the alimentary track and through respiratory
surfaces. Thus, the pollutants can be taken up in the form of food and through ambient water
(Walker et. al., 2006). If the organic pollutants are associated with particles (sediment or
suspended particles), and taken up by the respiratory system, they could be deposited in the
respiratory tract of the organisms. This is however a complex situation and as yet, the
knowledge available on the matter is scarce (Walker et. al., 2006).
A simplified model for the fate of a xenobiotic involves five types of sites: sites of uptake,
metabolism, action, storage, and excretion (Walker et. al., 2006). Once a pollutant enters an
organism, it can proceed towards the following sites and be treated in adequacy to their
function within the organism:
Sites of action. In such sites the toxic chemical interacts with the organism at a molecular or a
structural level and the resulting activity resonates at the organism-level. In other words, the
xenobiotic has a noticeable effect on the organism (Walker et. al., 2006).
Sites of metabolism. In these types of sites, enzymes capable of metabolizing xenobiotics are
acting upon the foreign chemicals, causing detoxification. Thus, the organism is acting upon
the chemical (Walker et. al., 2006). This could be seen as a protection mechanism or as
efficiency in chemical breakdown.
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Sites of storage. In this case the xenobiotic is held in an inert state in which it does not act
upon the organism, nor does the organism act upon it (Walker et. al., 2006).
Sites of excretion. The result of excretion can be either the original chemical or a
biotransformation product (Walker et. al., 2006).
Figure 1. Simplified model of xenobiotic uptake and fate within an organism
In the simple model illustrated in figure 1, the toxic chemicals are transported (after uptake) to
the different compartments of the organism’s body. The movement of the xenobiotics into the
organs and tissues could take place by diffusion through membranes, and in the case of
lipophilic chemicals (such as AC) by lipid transport. If a compound is very lipophilic, it is
transported by lipoproteins in a dissolved form. After their partial decomposition, the
fragments of the lipoproteins are transported into cells and the bound lipophilic molecules are
carried along.
2.4 EFFECTS ON BEHAVIOR
Theoretically, all behaviours exhibited by an organism can be affected, to a certain extent, by
xenobiotics. The article realized by Atchison et. al (1996) presents a review of the types of
behaviours affected in aquatic animals. As noted here, there are three main types of
behaviours that can be impaired: foraging, vigilance, and burrowing.
Dysfunctional foraging behaviour leads to reduced resource uptake, which in turn can result
in reduced production (e.g. nutrients, animal growth). Very little is known about how toxic
compounds affect the appetite. As for food handling time (time spent from capture to
ingestion), it has been shown that it is increased as a result of repetitive rejection and
recapture (Atchison et. al., 1996).
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If the vigilance behaviour is affected by the xenobiotic, the vulnerability to predators that the
animal exhibits will increase. This can further lead to an increased mortality rate.
Burrowing behaviour can also be affected in the presence of toxic contaminants. This is
mostly exhibited as a refusal of the animal exposed to the toxin to burrow in the sediment, as
it would otherwise do under normal living conditions.
3. CHOICE OF TEST ORGANISMS
In this project we will investigate if the fragrance acetyl cedrene (AC) can be biotransformed
by molluscs, and to do so we will look at two abundant benthic bivalves that both exhibit
burrowing behavior but have different feeding strategies in the brackish waters of Roskilde
Fjord.
The organisms in this essay were chosen because of the close proximity to one of the major
estuarine systems in Denmark, Isefjorden and Roskilde Fjord. Both organisms are widely
abundant in coastal waters around the world, and are known to uptake and metabolize
xenobiotics (Rust et. al., 2004).
3.1 MYA ARENARIA
Easily recognized by its white elliptic shell with a grayish-brown periostracum, M. arenaria’s
distinct feature consists of two merged siphons extruding at the posterior rounding of the shell
(see figure 2). M. arenaria can grow up to 140 mm in length and have relatively large siphons
compared to its body mass, which allows it to burrow up to 250 mm into to the sediment. This
depends on the size of the individual, the larger the individual the deeper it can burrow
(Wanink & Zwarts, 1989; Zaklan & Ydenberg, 1997). M. arenaria is a suspension feeder and
is feeding strictly on the phytoplankton (maybe also other small particles) suspended in the
water column and therefore has little to no uptake of sediment. These bivalves can be found in
densities of up to 4000 individuals m-2
in estuarine areas with muddy sediment (Möller &
Rosenberg, 1983).
Figure 2. Mya arenaria. This mollusc burrows deep in the sediment, extruding its
siphons to the surface of the sediment in order to feed (image source: Wheeler, J.).
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3.2 MACOMA BALTHICA
This tellinid bivalve can be recognized by its triangular oval shell, which is smooth with a few
concentric ridges and white, pinkish or orange in color (see figure 3, left). It can grow up to
35mm in length. The siphons of M. balthica are relatively long compared to the weight of the
organism and allows it to burrow up to 80mm into the sediment depending on its size. The
burrowing behavior of this species is also dependent on the seasonal change, as M. balthica
burrows deeper into the sediment in the winter (Wanink & Zwarts, 1989). M. balthica can be
found at densities of up to 1500 individuals m-2
(Olafsson, 1986). The feeding behavior of M.
balthica both relies on suspension feeding and syphoning in the surface layer of the sediment,
thereby both being a suspension and deposit feeder (see figure 3, right). In stagnant water M.
balthica almost solely (95-99% of the time) uses the deposit feeding strategy (Olafsson,
1986). This choice of feeding behavior is also dependent on the availability of organic
material in the water column (Lin & Hines, 1994). Lin and Hines also point out that the
competition for food in the water column has a strong effect on the choice of feeding strategy
of M. balthica, as the presence of high densities of other benthic organisms in the sediment
lowers the amount of food in the water and thereby forces M. balthica to change to deposit-
feeding.
Figure 3. (left) Macoma balthica. This image clearly illustrates the organism’s siphons. (right) even though M.
balthica mostly obtains its food through deposit-feeding, it can still change its strategy to suspension-feeding if
competition for food is low (image source: de Goeij & Luttikhuizen, 1998).
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As mentioned above, both molluscs exhibit burrowing behavior. The movements performed
by the organisms while burrowing increase the oxygen availability in the sediment, which
increases microbial degradation of organic compounds (Kristensen, 2000). Mya arenaria
being the least mobile of the species should have the lowest impact on the sediment (Phelps,
1989). And Macoma balthica, which is known to move more around in the sediment, could
have a larger impact on microbial biodegradation (Tallqvist, 2001).
It has been shown that though M. arenaria is better at metabolizing PAHs than M. balthica,
they are not as effective as other benthic species (Rust et. al., 2004). These results also
suggest a high bioaccumulation potential of M. balthica as a low metabolic rate combined
with a high rate of sediment ingestion and relatively long ingestion time compared to other
bivalves could add to the bioaccumulation of PAHs through the food web (Cammen, 1980;
Decho & Luoma, 1991). Bivalves have a 2-step uptake pathway; the first part involves
extracellular digestion in the intestines and is not very effective for xenobiotic uptake, though
research suggests that it differs from species to species (Decho & Luoma, 1991). The second
pathway, involving intracellular digestion by the digestive glands shows a much higher
absorption rate and takes much more time than the first one (Decho & Luoma, 1991).
4. BIOACCUMULATION AND BIOTRANSFORMATION
Contaminants can accumulate in the body, tissue, and gut of organisms by means of
adsorption, absorption, diffusion, exposure to a contaminant, or through the feeding habits of
the organism. The substance is bioaccumulated when it is absorbed at a higher rate than it is
excreted.
4.1 BIOAVAILABILITY
- can be explained, as stated in Spacie’s article, as ‘the portion of the total quantity or
concentration of a chemical in the environment or a portion of it that is potentially available
for biological action, such as uptake by an aquatic organism’ (Spacie, 1995). In other words,
bioavailability describes the amount of a compound that is available for uptake and
biotransformation by an organism.
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Figure 4. The amount of readily available xenobiotic decreases with time
(image source: Semple et. al., 2003)
Hydrophobic organic compounds like PAHs are believed to have a similar bioavailability
pattern where bioavailability of the compound is lowered over time due to adsorption to and
absorption in particles in the system. The fate of these compounds is usually divided into 2
main fractions; a readily available fraction which interacts with particles in the system via
weak bonds and van der waal forces, and a more slowly absorbed recalcitrant fraction where
covalent bonds and other more complex interactions are formed with organic particles in the
sediment, thus making the compound less bioavailable (as this happens within several weeks
it is not relevant in this work).
When the compound is strongly bound to the sediment particles it becomes unavailable to the
organism as the sediment particles are not degraded or destroyed by the organism, thus the
particles are able to retain the compound and the particle bound compound is then excreted
and returned to the sediment.
As seen in figure 4, the more readily available fraction decreases with time as more strong
bonds are formed and degradation takes place. The time in which these bonds are formed
varies greatly dependent on mineral and organic content, temperature, pH, properties of the
xenobiotic, size and surface area and structural/spatial complexity of particles in the sediment
(Reid et. al., 2000; Semple et. al., 2003).
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4.2 BIOTRANSFORMATION
Biotransformation, also known as xenobiotic metabolism, can be defined as the chemical
process through which a xenobiotic is modified (broken down into simpler forms) by biologic
entities (micro-organisms, plants, animals) in the presence or absence of oxygen (Walker et.
al., 2006). This process often leads to a reduction in toxicity or to the transformation of the
compound metabolised into a non-toxic form. There are also cases in which the toxicity of a
xenobiotic can be enhanced or activated (Landis and Yu, 1999). A simplified model of this
process is illustrated in figure 5.
Figure 5. The different steps of biotransformation (image source: Walker et. al., 2006).
Organic contaminants are likely to be biotransformed (once they are taken up by the organism)
into a more water-soluble form is mediated by enzymes (Jørgensen et. al., 2005). The
metabolism of most lipophilic xenobiotics takes place in two phases. The initial step of
biotransformation, also called phase I, consists of processes such as oxidation (during which -
COOH, -OH, -NH2, -SH can be added), hydrolysis, hydration, or reduction, and results in
metabolites characterised by their hydroxyl groups (e.g. hydroxyl-PAHs or dihydrodiols).
These hydroxyl groups will then be used during most of the following conjugation reactions
that make up the second step of biotransformation (phase II). These metabolites are often
more reactive compounds and are easily conjugated to more easily metabolized naturally
occurring compounds such as sugar derivatives, peptides and sulphates (Selck, 2002). During
phase II of PAH biodegradation, aqueous PAH-metabolites are produced (epoxides and
phenol oxides, by means of conjugation) which are ionisable or more water soluble and can
be readily excreted. (Jørgensen et. al., 2005). Figure 5 presents a simplified model of
biotransformation.
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5. MATERIALS AND METHODS
Both sediment and test organisms were collected from Roskilde Fjord (55°43'N, 11°58'E,
Gershøj, Denmark) on the 27th
of February, 2013. Since the amount of sediment collected
proved to be insufficient, Isefjorden (55°67'N, 11°80'E, Munkholm, Denmark) was used as a
second collection site (see figure 6). The ratio of the sediment from each of the two sources
was roughly 0.5 and was mixed prior to the commencement of the experiment.
Figure 6. Map of collection sites. The blue star represents the first collection poin, while the red star indicates
the origin of the latter sediment collection.
5.1 SEDIMENT: COLLECTION AND HANDLING
The sediment was collected, using a 500µm sieve, by scraping the surface of the sediment.
Since the sediment surface was mostly covered my marine macroalgae, the sediment was
collected from random patches that were not completely covered by the algae. Thus, it was
tried to collect it without uptake of marine plants.
The salinity of the water was measured with a refractometer in two different places: close to
the shore, where it had a value of 4‰, and more further out, where the value measured was of
10‰. As for the temperature, the value displayed on the thermometer was of 1°C.
After sieving, the sediment was washed with distilled water. It was kept overnight for a period
of 24h to allow the sediment to settle, after which the overlaying water was removed and
replaced with seawater (10‰ salinity). Each time new water was added atop of the sediment,
the mixture was thoroughly homogenized. The homogenization was performed in order to
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assure that the seawater penetrated the sediment evenly, since the sediment has a tendency to
settle and accumulate at the bottom of the recipient in which it was kept. This procedure
(change of overlaying water and homogenization of sediment) was done twice, the purpose
being to raise the salinity level of the sediment up to 10‰.
After 48h, the overlaying water was removed and the sediment was homogenized again, it
was evenly distributed in re-sealable plastic bags, labeled, placed in the freezer at a
temperature of -20°C to destroy any organisms that might be present in the sediment, and
preserved until further use.
The next step consisted of thawing the sediment, homogenizing it thoroughly, and
determining the dry weight to wet weight ratio (dw:ww). The wet weight was determined by
weighing the wet sediment on an aluminum boat. Three samples were weighed and the
average of 6,0466g was used for the dw:ww ratio. The wet sediment from the three samples
was then introduced into a muffle furnace and kept at 105°C for 24h. After 24h, the sediment
was removed from the oven, cooled down, and re-weighed. The average of the dw (which
had a value of 4,5769g), and the average of the ww, gave a ratio of 0,7569. The ratio was
rounded up to 0.76 to ease further calculations. For complete calculations see Appendix A,
table 9.
5.2 SEDIMENT SPIKING WITH ACETYL CEDRENE
The first step in establishing the amount of AC needed for spiking was to determine
the quantity of ww sediment needed for the experiment. The amount was chosen to cover 21
beakers of 600ml (143mm height, ∅82mm, DURAN) and a depth of 4cm (this height was
chosen to fulfil the burrowing needs of the organisms studied).
The glass beaker (600ml) was weighed at 118.270g, and then sediment was added until it
reached the hight of 4cm. When weighed with sediment, the beaker gave a new mass of
292.074g. This accounted for 173.804g of ww sediment added per beaker, value that was
rounded at 180g.
After that it was decided that a 250ml beaker might be better for the experiment set-up, so the
amount of ww sediment needed per beaker was scaled down by dividing the initial amount by
2. This gave a quantity of 90g of ww sediment needed per beaker.
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At the time of the initial calculation for the amount of AC needed for sediment spiking, the
experiment set-up consisted of 21 beakers with AC treatment.
The calculations went as following:
90g ww * 21 beakers = 1890g ww sediment (total amount of ww sediment needed for spiking)
An extra of 310g ww sediment was added (to ensure that the amount spiked was enough for
the set-up).
Thus, 2200g ww * 0.76 dw:ww ratio = 1672g dw sediment
50µg AC/g dw sediment * 1672g dw sedediment = 83600µg AC = 83.6 mg AC ~84 mg AC
(amount of AC needed for spiking)
The 84 mg of AC were used to create a stock sediment (2.4828g).
Both the Control sediment (no added AC) and the sediment treated with AC were handled in
the same way. In table 2 the actual amount of AC added to the stock sediment can be seen.
Table 2. Values for spiked and Control sediment. In the Control, water was used to replace the AC.
Aluminum boat (g) Sediment (g) H2O 10% (g) AC 50µg (g)
Control 7.8118 2.3674 0.1216 -
AC treatment 7.8136 2.4828 - 0.0871
The stock sediment was then added to 2.2kg of wet sediment. After that, the spiked sediment,
as well as the Control sediment, was hand mixed in the fume hood and placed on a shaking
table for 24h. The two types of sediment were additionally hand mixed several times
throughout a two-day period. This was necessary in order to prevent the sediment from
settling on the bottom of the buckets in which it was kept and to thoroughly homogenize it.
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5.3 TEST ORGANISMS: COLLECTION AND HANDLING
All the organisms were collected from Roskilde Fjord (55°43'N, 11°58'E, Greshøj,
Denmark) on the 27th
of February, 2013. Macoma balthica was obtained by removing the
sediment from the surface with a shovel and sieving it with a 2mm sieve, while Mya arenaria
was harvested by digging deeper into the sediment. Macoma balthica was mainly collected
from the areas that were more out sea (10‰ salinity), while the Myas were also collected in
the areas situated close to the shore (salinity 4‰ and 10‰). The organisms were sampled
randomly and a total of 38 Macomas and over 200 Myas were found.
It was also intended to use Cerastoderma glaucum as a test organism.182 Cersatodermas were
collected, mostly from the areas that measured a salinity level of 4‰. Unfortunately, they
were all dead by the end of the experiment, thus they were not included in the experiment set-
up section of this report.
The next step consisted of acclimatizing the organisms from a temperature of 1°C, found in
the natural environment, to 17°C, the temperature used for running the experiment.
The organisms were brought into a climate room set to run at 4-6°C and sorted. They were
then placed into plastic containers with sediment from the field, water (10‰ salinity), plastic
cover, and were linked to an air supply. Each 3-4 days the temperature was raised by several
degrees, from 4-6 to 10 to 17°C. The overlaying water was changed several times during the
acclimatization period to offer a better living environment for the organisms.
At the time of collection, all the participants in the process had a rough idea of the organisms
that were being searched for. Thus, a few days into the acclimatization period, the organisms
were identified by using Havets dyr og planter by Køie M. et. al. (2000) and The brackish-
water fauna of northwestern Europe by Barnes R. S. K. (1994).
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5.4 EXPERIMENT SET-UP
Before setting up the experiment, because most of the organisms died, due to
inadequate handling, it was decided to reduce the actual experiment size down to 18 beakers:
9 for Control (3*Macoma, 3*Mya, and 3*without organisms) and 9 beakers with 50µg AC/g
dw sediment (3*Macoma, 3*Mya, and 3*without organisms)(see figure 7).
Figure 7. Experimental set-up. The treatment groups were divided in Control (no AC) and AC-treated group. In
each of the beakers containing M. balthica and M. arenaria, 4 test organisms were added. Two additional groups
with no organisms were added to the experimental set-up to assess microbial degradation. Each group had a total
of 3 replicates.
Sediment was added to each beaker (clean sediment to the Control beakers and treated
sediment to the AC beakers) up to the level of 2 cm. Initially, the limit was 4 cm, but since the
beakers were changed from 600mL to 250mL (117mm height, ∅61mm, DURAN), the
sediment height was also diminished. Next, water (10‰ salinity, filtered with 10µm) was
added up to the 200ml mark of each beaker. The beakers were covered with parafilm (to
prevent evaporation of water), and air supply was ensured by air pumps connected through
tubes to glass Pasteur pipettes (see figure 8). This set-up was kept for two days, after which
the overlaying water was carefully removed (without disturbing the sediment) with a
volumetric pipette and replaced with new water (10‰ salinity). Changing the overlaying
water is an important step because decomposing organic chemicals enter the water phase and
can pose a threat for the test organisms.
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Figure 8. Experimental set-up. Parafilm was used to
prevent evaporation of AC, as well as to offer support for
the air pumps.
The overall sizes of the organisms collected were in between 1.0 – 2.2cm for Mya arenaria
and 0.8 – 1.7cm for Macoma balthica. Upon dissection it was determined that the Macomas
with a size of 1.2cm were equal in biomass (~0.081g) with the Myas of size 1.4cm.
Due to restrictions in organism numbers (only 38 Macomas were available), it was decided to
add 4 organisms per beaker (corresponding to a density of 1,428 organisms/m2
) and the sizes
selected for each of them were: 0.8 – 0.9cm; 1.0 – 1.1cm; 1.1 – 1.2cm; 1.3 – 1.4cm for
Macoma, and 1.0 – 1.1cm; 1.2 – 1.3cm; 1.5 – 1.6cm; and 1.7 – 1.9cm for Mya (one organism
from each range specified)(see figure 7). These sizes were selected because they had
matching biomass and were the most representative for the sampled populations. Next, the
organisms were gently added to the beakers. The experiment was conducted for a 14-day
period with the climate room set at the temperature of 17°C.
During the preparation phase all the components of each beaker (Control and treatment) -
sediment, water, and test organisms - were handled in precisely the same manner to avoid
errors that can arise from reasons unrelated to the actual effects of the chemical.
Additionally, 3 beakers (T0 1, T0 2, T0 3) with AC and no organisms were made for determining
the initial conditions (i.e. the initial AC levels). They were kept for two days (under same
conditions as the experiment set-up), and taken down, the sediment and water being
separately stored in the freezer at -20°C.
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5.5. BURROWING BEHAVIOR
The burrowing behavior of the organisms was monitored and noted down half an hour, 1 hour,
and 8 hours after the exposure start. During the 2-week period in which the experiment was
running, the set-up was checked upon once a day to make sure the oxygen supply was
functioning properly. Any dead organisms found were removed and noted down. The
burrowing behavior and mortality can be seen in Appendix B.
The burrowing behavior was monitored in order to make sure that the test organisms accept
the environment they were settled in and to see if they behave as expected. Under normal
conditions, both species are normally burrowed completely in the sediment, having only their
siphons extruding from it. %
5.6 WATER, TISSUE, AND SEDIMENT ANALYSIS
After the 14-day period of exposure ended, the water, sediment, and organisms were prepared
for further analysis.
WATER. The first step consisted of removing the overlaying water with a 10ml pipette,
determining the amount of water existent per beaker, and storing it in labeled blue-cap bottles
(100ml, VWR). The volume of water existent per beaker ranged 130-140ml (see Appendix C,
table 11 A and B). After, the water samples were placed in labeled plastic bags and frozen at -
20℃.
TISSUE. Next, the organisms were taken out of the experimental beakers, rinsed with miliQ
water, and left to clean their guts overnight (in new beakers with clean water, 10‰ salinity,
and air supply). They were then dissected, the tissue being placed in labeled and re-sealable
test tubes, and frozen at -80℃.
SEDIMENT. The sediment was homogenized, placed in labeled and re-sealable plastic bags,
and frozen at -20℃ until further analysis.
PREPARATION OF SEDIMENT SAMPLES FOR GC-MS
The sediment corresponding to Mya (sample 1, 2, and 3), Macoma (sample 1, 2, and 3),
microbial degradation (sample 1, 2, and 3) with AC addition, and Mya (sample 1, 2, and 3),
Macoma (sample 1, 2, and 3) without AC addition were thawed in warm water.
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Aluminum trays were used to weigh 5g of wet sediment (from each individual sample), while
a corresponding 5g of Diatomaceous Earth (Hydromatrix) were weighed separately (for exact
measurements, see Appendix E, table 12). The sediment was mixed with the hydromatrix and
homogenized using plastic spoons.
The ASE extraction cells were prepared by adding two cellulose filters. 2.90 – 3.10g of silica
gel were then added to the extraction cells, as a safety measure for avoiding water, and
compressed with the insertion tool. A metal funnel was used to ease the process. Half of the
mixture of sediment and hydromatrix belonging to every sample was then added to their
corresponding ASE cell and compressed with the insertion tool. Next, 100!l of internal
standard was added. The internal standard chosen was phenanthren-d10 (1500!g/ml toluene).
For safety reasons, this step was performed under the fume hood. The remaining half of the
sediment and hydromatrix mixture was added on top of the internal standard and compressed
with the insertion tool, hydromatrix being used to fill the cell up to 1cm from the top.
The cell was closed and placed on the Cell Tray of the ASE machine for sample extraction.
Labeled glass vials were placed on the Vial Tray in the places corresponding to the extraction
cells (see figure 9, left).
In preparation of the ASE, the EPA-type VOA glass vials were kept in an oven at 550℃!to
make sure there were no organic contaminants and the dichloromethane (CH2Cl2) was placed
on an ice bath 2h prior to using the ASE machine.
The program selected for the ASE machine was:
a. Preheat (0 min)
b. Heat (5 min)
c. Static (15 min)
d. Flush (50 vol)
e. Purge (60 sec)
f. Cycles (2)
g. Pressure (2000 psi)
h. Temperature (60℃)
i. Solvent (Dichloromethane, 100%)
More details on the function of the ASE200 machine are presented in Appendix D.
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After all the cells were processed, the glass vials were taken to evaporate on the Evaporator
SE 500 (see figure 9, right). Prior to that, 1 ml of toluene was added to each vial.
Figure 9. (left) The ASE extraction cells being loaded on the Cell Tray.
(right) Sample evaporation on the SE 500 machine.
The program used on the SE 500 machine was:
a. Entry 1: Direction = CW
b. Entry 2: Time ON (Secs.) = (do not select any value)
c. Entry 3: Time ON (Mins.) = (do not select any value)
d. Entry 4: Time ON (Hrs.) = (do not select any value)
e. Entry 5: Pulse/Min = 70 (which was later reduced to 50)
f. Entry 6: Duty Cycle = 90%
g. Entry 7: Setpt 1 = 15 deg. C (Top Manifold)
h. Entry 8: Setpt 2 = 75 deg. C (Bottom block)
The remaining samples were filtered by using a glass pipette, glass wool, and anhydrous
sodium sulfate (Na2SO4) to prevent any water from ending up in the GC-MS machine, and
then washed with toluene into a 5ml volumetric flask. The samples were then transferred to
GC-MS vials, closed with a cap, and stored at -20℃.
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The T0 samples, that were removed at the beginning of the experiment, were also prepared for
the GC-MS analysis in the same way as the rest of the samples. Details on preparation for the
ASE machine and on dw:ww measurements can be seen in Appendix A and E (table 10 and
12).
Separately, the dw:ww ratio was determined. Aluminum trays were weighed, and 2g of
sediment was added in order to determine the ww. Next, the sediment trays were added into
an oven and kept overnight at 105℃. The sediment treated with AC, and the one without,
were added to the oven at different times: 13:45, respectively 15:42, and were extracted from
the oven at the same time, 14:00. The results can be seen in Appendix A, table 10.
PREPARATION OF TISSUE SAMPLES FOR GC-MS
The tissue sample tubes were taken out of the freezer, defrosted and placed on an ice bath.
2ml of MeOH and 2ml of water were added to each centrifuge glass containing tissue samples.
The contents of the centrifuge glass were mixed with a Homogenizer and the tubes were
placed back on the ice bath.
The method used for packing of the ASE extraction cells with the tissue sample was mostly
similar to the one used for packing the sediment samples. The difference consists of 4g of
hydromatrix being mixed with the tissue. The entire homogenized mixture was then added to
the extraction cell, followed by the internal standard that was added last.
The preparation for the ASE200 machine was exactly the same (i.e. the glass vials kept in an
oven at 550℃, the dichloromethane kept on ice, the program used by the machine).
During the removal of the EPA-type VOA glass vials, the Macoma 3 sample treated with AC
was broken due to human error.
The program used for the evaporation on the SE 500 machine was the same as used during the
sediment preparation. After the evaporation, the remaining samples were filtered by using a
glass pipette, glass wool, and anhydrous sodium sulfate to prevent any water from ending up
in the GC-MS machine, and then washed with toluene into a 5ml volumetric flask. The
samples were then transferred to GC-MS vials, closed and stored at -20℃.
26"|"P a g e "
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PREPARATION OF WATER SAMPLES FOR GC-MS
The volume of each sample was measured and transferred to conical flasks. The values
measured ranged between 66-77ml. All the samples had precipitate on the bottom and it was
tried as much as possible to pour without disturbing it. In microbial degradation (1) all of the
precipitate ended up in the conical flask. Note: In the lower section of the samples treated
with AC, colloids could be observed. It was tried as much as possible to avoid taking them up
while pouring the samples.
The extractions were done in two rounds to ease handling:
Round 1: Microbial degradation 1, 2, and 3 + Mac 1 and 2;
Round 2: Mac 3 + Mya 1, 2, and 3.
The compounds from the water were removed through Solid Phase Extraction (SPE), by using
Strata-XL tubes from Phenomenex (500mg/6ml, 100u Polymeric Reversed Phase). The SPE
consists of a number of 6 steps.
1. Condition. A vacuum manifold was used, and 3 ml of methanol (MeOH) were flushed over
each column to wash and activate the filter. The vent was adjusted to secure the constant flow
of 3ml/minute.
2. Equilibration. To rinse the tube from MeOH, an additional 3ml of water were used. Again, the
vent was adjusted to secure the constant flow of 3ml/minute.
3. Load sample. The AC-water samples were loaded on the vacuum manifold. The vacuum pump
was turned on and the vent on the vacuum manifold was adjusted at a flow of 3-10 ml/minute.
4. Wash. After all the samples went through the filter, each flask was flushed with 4 ml of water
and added to the column. It is important to flush the conical flasks so that all of the potential
compounds will go to the filter (this step was omitted for the Macoma 3 and Mya 1 samples
due to human error).
5. Dry. The vacuum pump was kept on for 2 minutes, time in which the samples were dried out.
After this step, the vacuum pump was turned off.
6. Elute Analyte. 3 ml MeOH were added to the tubes to elute the compounds collected by the
filter. Collection flasks were placed under the SPE tubes.
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Because the GC-MS machine’s column can be damaged in the presence of water, sodium
sulphate was used to remove any trace of it from the samples. Glass wool was added to glass
pipettes. Separately, a minute amount of Na2SO4 (on the tip of a small metal spoon) was
placed in each sample glass. The Na2SO4 binds to H2O, impeding its access through the filter.
The sample microbial degradation (3) was the only one that was handled slightly different, by
adding Na2SO4 in the glass pipette, on top of the glass wool. The sample was then filtered
through it. The microbial degradation (3) was the first sample to be processed and the
procedure used on it did not seem to be efficient enough, thus the change in method was made.
The small flasks with the eluted compounds in MeOH were each added 500µl of toluene and
100µl (at first only 50µl was added and halfway through the evaporation another 50µl was
added) of the internal standard, phenanthren-d10 (1500µg/ml toluene) and placed on the
Evaporator (SE500). Toluene is lipophilic and it will capture AC and keep it from evaporating.
When the samples are evaporating, only the MeOH will evaporate while the toluene and
lipophilic compounds will remain.
Most of the samples were almost dry after evaporation due to inadequate monitoring (they
were in the machine for half an hour and there was still MeOH left in the glasses; after
another hour in the machine, they were almost completely dried out). To recover the samples,
1000µl of toluene was added to all of the vials, after which they were sonicated for two hours.
Because of precipitate on the bottom, the samples were filtered one more time. Sodium
sulphate was added to the samples and Pasteur pipettes with glass wool and sodium sulphate
atop were used. The rinsed samples were collected in the GC-glasses and stored in the freezer
until further use.
5.7 GC-MS ANALYSIS
The GC-MS instrument used for the AC analysis consisted of a 6890N Network GC System,
MS 5975, and a 7683B Series Injector, from Agilent Technologies (for a general description
of the function of the GC-MS, see Appendix F).
The method ran was called SIM (single ion monitoring) and the sub-method chosen was AC
with Phenanthrene-d10. SIM is used if the purpose of the analysis is to quantify something (in
our case AC).
28"|"P a g e "
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For the analysis of AC, a blank containing dichloromethane was placed on the autosampler to
commence the sequence. The purpose of this first blank (Blank1) was to rinse the needle of
the injector before proceeding to the samples treated with AC. Next followed the water,
tissue, and sediment samples. Seven more blanks were added in between the samples at a 5-7-
step interval, the final blank (Blank8) following the last sample. At the end of the sequence, 4
GC-MS-vials with different concentrations of AC (30, 100, 150, 250 !g) were mounted on the
autosampler and used to calibrate the machine.
The T0 sediment samples were ran separately on the GC-MS, the loading sequence being
T0(1), T0(2), T0(3), AC 30, AC 100, AC 150, AC 250. They were treated in the same way as
all the other samples.
As the GC-MS is started, the needle of the injector is firstly washed with CH2Cl2. Only after
this step has been performed, the first sample is taken for analysis (in our case Blank1). It
takes 28.95 minutes for the machine to process one sample, and some cooling time in between
samples is also required.
The parameters used for running the GC-MS instrument were:
Inlet-F Temperature – 250℃ (the temperature required for changing phase from liquid to gas);
Column Flow – 1.0 ml/min (represents the speed of carrying the analyzed compound with
helium. Helium is chosen in our case because it doesn’t interact with AC);
Inlet-F Pressure – 8.1 Pa;
Oven Temperature - 80℃;
Inlet-F Total Flow – 23.8 ml/min (this parameter illustrates the flow of gas used to rinse the
machine);
MS Quad – 150℃!(the temperature in the quardupole);
MS Source – 250℃;
HiVac – 6.20e-006 (the vacuum inside the MS);
These numbers represent the parameters existent at the beginning of the analysis (t = 0
minutes). It should be noted that some parameters change over time (e.g. the oven
temperature). The program used for the oven can be seen in table 3.
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Table 3. Program used for the temperature increase in the oven
Step ℃/min Next ℃ Hold min
Initial 80 2.00
Round 1 20.00 165 11.00
Round 2 50.00 200 2.00
Round 3 20.00 280 5.00
As the first sample is harvested by the injector, 1!l of the mixture of AC and phenanthrene-
d10 is injected into the GC unit. The mixture is carried further by helium and is vaporized as
the temperature reaches 250℃. Helium was chosen because it does not react with AC. In the
oven, the chemicals are guided by the helium along the column (length 30m, ∅0.25, DB-1701,
Agilent Technologies), and the temperature is slowly increased from 80 to 280℃. Inside the
column the compounds are sorted by boiling point and polarity, so that the compound with the
lowest boiling point is lead through first and the heavier compounds last. After passing
through the column, the chemicals enter the MS unit. In the MS there is a vacuum and
therefore no other molecules, except the ones lead there by the column. Here the compounds
are bombarded with electrons, thus making them lose electrons and create positive ions. Most
positive ions of organic compounds are charged with a surplus of energy and in the absence of
other ions the molecule will split into ion fragments. These ion fragments represent the
specific fingerprint of the molecular ion. Each ion has a specific mass to charge ratio (m/z)
and is lead through a small hole in a negatively charged plate and into the quadrupole. The
charge between the poles in the quadrupole changes with a frequency of 1 MHz (1.000.000
times/sec). At a set current and frequency, only ions with a specific mass to charge ratio will
pass through. The current, produced by the ions, is amplified by an electron multiplier
HED/EM (High Energy Dynode/Electron Multiplier). In the HED, the flow of ions from the
quadrupole hits a dynode that releases electrons. Each of these electrons hits the inner walls of
the EM and releases more electrons. This electron flow is shown as a peak on the GC graph,
where the area under the curve is an expression of the amount of ions. When running the SIM
programme, the current and frequency is changed over time so that the ions will be “sorted”
by their mass to charge ratio. This change can occur between 1 and 10 times/sec. If the change
in current and frequency is set too fast, the sensitivity will be lowered. A strong current
increases the sensitivity, but shortens the lifespan of the machine.
Three types of reference ions were selected for both AC and the internal standard:
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Group 1 – the AC ions – Consisted of the target ion 246.00 m/z (Tgt), and two qualifying
ions: 161.00 m/z, 231.00 m/z (mass/charge)(Q1 and Q2).
Group 2 – Deuterium phenantherene-d10 ions – Consisted of the target ion 188.00 m/z (Tgt),
and the qualifying ions: 80.00 m/z and 189.00 m/z (Q1 and Q2).
5.8 STATISTICAL METHODS
In order to test the hypothesis of this report, the General Linear Model Test and One-Way
ANOVA were used. The Tukey Test was also used to assess the differences between
individual samples. The program used for computing all the statistical data was SYSTATS.
The analysis of variance (ANOVA) is used to investigate the differences between the means
of two or more samples. A prerequisite of ANOVA is that the samples that undergo analysis
must be evenly distributed. The reason for choosing One-Way ANOVA is because we were
dealing with only one parameter (AC concentration).
The General Linear Model Test was used merely because it offered more options than
ANOVA, while still including the analysis of variance.
While performing the tests, the confidence interval chosen was always 0.95. As additional
options, the normality test, Kolmogorov-Smirnov, and the Equality of variance test, Levene,
were chosen.
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6. RESULTS
During the exposure of the organisms to AC and after the analysis of the water, tissue, and
sediment samples on the GC-MS machine, two different sets of effects have been monitored.
They can be grouped into effects of AC on the test organisms (these have been observed
through behavioral changes and assessment of mortality levels) and fate of AC (change in AC
concentration in water, sediment, and soft tissue).
6.1 EFFECTS ON ORGANISMS
MORTALITY
Table 4 offers an overview of the number of organisms that were alive at the end on the
experiment exposure and their biomass.
Table 4. Tissue weight and corresponding number of organisms for:
A. Mya arenaria, and B. Macoma balthica
AC TREATMENT AC TREATMENT
Weight (g) Nr. of org. Weight (g) Nr. of org.
Mya 1 0.1865 1 Mac 1 0.2683 1
Mya 2 0.2800 2 Mac 2 0.3088 2
Mya 3 0.4481 3 Mac 3 0.4182 4
CONTROL CONTROL
Mya 1 0.0998 2 Mac 1 0.0628 4
Mya 2 0.1368 2 Mac 2 0.1395 3
Mya 3 0.0753 2 Mac 3 0.2039 2
During the 14-day exposure period, a total number of 5 organisms died from the Mya AC
groups, while 4 organisms died from the Macoma AC group
From the mortality graphs (figure 10 and 11), we can see that under similar conditions,
Macoma balthica has a higher resistance to environmental stress than Mya arenaria, since
less organisms from the Macoma group died, compared to the Mya group.
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Figure 10. Cumulative comparison of mortality of Mya between Control and samples treated with AC.
From comparing the two graphs we can see that the Myas began dying already from the
second day of exposure, whereas the Macomas - on the 5th day.
Figure 11. Cumulative comparison of mortality of Macoma between Control and samples treated with AC.
BURROWING BEHAVIOR
During the exposure period, the burrowing behavior of the test organisms was observed. This
was done in order to see how the organisms perceive the sediment they were introduced to, if
they accepted the conditions (i.e. AC treatment, no treatment), and if they behave as predicted.
Under normal circumstances, the organisms would instantly start burrowing once placed atop
of the sediment. In the presence of AC, this behavior might be altered as the organisms might
consider the new environment ‘unfit’ for burrowing.
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To obtain a better overview of the burrowing behavior exhibited by Macoma balthica and
Mya arenaria during the 14-day exposure interval, the burrowing-table from Appendix B was
used to see how often (in %) the organisms would be inside, outside, or halfway in the
sediment.
1) Macoma AC and Macoma Control
After summing up all the instances in which the organisms would be in, out, or halfway in the
sediment, it was found that in the groups treated with AC, Macoma would be burrowed in
~64,5% of all the possible cases, halfway burrowed in ~18,5% of the cases, and atop of the
sediment in 17% of the cases. As for the Control group, Macoma was burrowed in ~70% of
the cases, halfway in ~10,5%, and out in ~19,5% of the cases.
Macoma’s burrowing behavior shows that in most of the cases they burrow well and stay in
the sediment. This applies for both Control and AC treated samples. There were however
some Macoma that did not burrow fully or stayed above the sediment. That might be due to
individual preferences. In general, the behavior from both types of treatments follows a
similar pattern. Figures 12 and 13 offer a better view of the behavior exhibited by the
organisms form the Control and AC groups, during the 14-day exposure period.
%%%%%%%%%%%%%%%%%% %
Figure 12. Burrowing behavior exhibited by Macoma in the Control groups.
From figure 12 we can see that 8 out of 12 organisms burrowed in the sediment as soon as the
exposure began. This is a good sign of organism fitness and shows that the organisms were
not affected (stressed) too much during the acclimatization and exposure period.
0%
2%
4%
6%
8%
10%
12%
1/2h%
1h%
8h%
d1%
d2%
d3%
d4%
d5%
d6%
d7%
d8%
d9%
d10%
d11%
d12%
d13%
d14%
in%
h%
out%
Macoma%Control%Burrowing%Behavior%
No.of%organisms%
Time%
34"|"P a g e "
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From figure 13 we can see that it took a one full day for the Macomas from the samples
treated with AC to burrow in the sediment, compared to the ones from the Control samples
that burrowed fully within the first 1/2h. Also, the number of organisms that chose to not fully
burrow or not burrow at al was slightly higher in the AC treated group compared to the
Control group.
%%%%%%%%%%%%%%%%%%
Figure 13. Burrowing behavior exhibited by Macoma in the groups treated with AC.
2) Mya AC and Mya Control
The burrowing of Mya was not as successful as that of Macoma. It was expected that they
would go in the sediment but they mainly stayed partially burrowed and close to the surface
of the sediment.
In the AC treatment, the organisms were burrowed in 25,5% of the cases, halfway in the
sediment in ~52% of the cases, and out ~22,5% of the time. In the Control group, ~22% of the
time the Myas were burrowed, they were halfway in the sediment ~18% of the cases, and the
remaining ~60% of the time they were atop of the sediment.
Figures 14 and 15 illustrate the burrowing behavior of Mya in the Control samples and in the
samples treated with AC. From these graphs we can see that Mya has a chaotic distribution of
organisms, both in the Control and AC group.
0%
2%
4%
6%
8%
10%
12%
1/2h%
1h%
8h%
d1%
d2%
d3%
d4%
d5%
d6%
d7%
d8%
d9%
d10%
d11%
d12%
d13%
d14%
in%
h%
out%
Macoma%AC%Burrowing%Behavior%
Time%
No.of%organisms%
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Figure 14. Burrowing behavior exhibited by Mya in the Control groups.
In both the Control and AC group there is a tendency for the organisms to burrow in the
sediment, after which the tendency slowly turns towards going out of the sediment. In the
Control it can be seen that in day 4 there are just 4 organisms out of the sediment, one day
later the number increasing to 10, after which, on the 9th day the number goes down to 3. This
could be explained by the fact that the organisms that went out of the sediment, after being
previously burrowed, simply died and were removed.
Figure 15. Burrowing behavior exhibited by Mya in the groups treated with AC.
0%
2%
4%
6%
8%
10%
12%
1/2h%
1h%
8h%
d1%
d2%
d3%
d4%
d5%
d6%
d7%
d8%
d9%
d10%
d11%
d12%
d13%
d14%
in%
h%
out%
Mya%Control%Burrowing%Behavior%%
Time%
No.of%organisms%
0%
2%
4%
6%
8%
10%
12%
1/2h%
1h%
8h%
d1%
d2%
d3%
d4%
d5%
d6%
d7%
d8%
d9%
d10%
d11%
d12%
d13%
d14%
in%
h%
out%
Mya%AC%Burrowing%Behavior%
Time%
No.of%organisms%
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3) Comparison between species
The burrowing behavior of the two organisms gives us a clear insight on the different
responses that the two species have when dealing with the same stress factors.
When comparing the two organisms, we can observe that Macoma burrowed more readily
into the sediment compared to Mya and this may indicate that Macoma is more resistant to
external stress (the burrowing graphs from Macoma are stable and the mortality is lower
compared to Mya, that have fluctuating burrowing behavior and higher mortality).
6.2 FATE OF AC
The results obtained from the GC-MS machine, which are relevant to our study, can be seen
in table 5. These numbers were used to determine whether the AC added to the different
samples was biodegraded during the 14-day period in which the experiment was held.
Table 5. Amount of AC measured in sediment, water, and tissue on day 14, and initial amount (T0)
Treatment( Sediment(AC(
Body(
burden(
Water(
,, (ug/g), (ug/g), (ug/ml)%
Mya,ac,1, 23.1147, J% J%
Mya,ac,2, 23.1214, J% J%
Mya,ac,3, 25.0069, J%% J%
Mac,ac,1, 24.3754, 92.1729, J%
Mac,ac,2, 22.0136, 76.2953, J%
Mac,ac,3, 22.5651, DAMAGED, J%
T0,initial,ac,1, 37.1318, >, J%
T0,initial,ac,2, 35.6810, >, J%
T0,initial,ac,3, 40.8549, >, J%
Microbial,degradation,1, 28.1599, J, J%
Microbial,degradation,2, 22.1222, J, J%
Microbial,degradation,3, 21.2805, J, J%
No,organisms,1,(control), >, J, J%
No,organisms,2,(control), >, J, J%
No,organisms,3,(control), >, J, J%
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ACETYL CEDRENE IN SEDIMENT
As expected, all the sediment samples spiked with AC showed the presence of AC on the GC-
MS mass-spectrum. The presence of AC is showed in the form of a peak in the region where
the selected target ion, and the qualifying ions are found (see figure 16 and 17).
Figure 16. The small peak to the left represents the abundance of AC found in the sample. The peak to the right
represents the mass-ion spectrum for the internal standard, phenanthrene-d10.
Figure 17. The ions used for identifying AC were the target ion 246.00 m/z (Tgt), and the qualifying ions 161.00
m/z, 231.00 m/z (Q1 and Q2).
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Both One-Way ANOVA and the General Linear Model were used to test if our alternative
hypothesis (HA – AC conc. T0!≠ AC conc. Tend) is accepted or rejected. In other words, to see
if there is a notable difference between the amount of AC found in the T0 samples, and the
amount found in the Mya, Macoma, and microbial degradation samples, at the end of the
exposure period.
A bar chart graph was selected to better illustrate the differences in AC amount (!g/g) found
in the T0 samples, and the ones found in the no-AC/no-organism sample (Control), and the
Mya, Macoma, and microbial degradation samples treated with AC (see figure 18).
Figure 18. (left) Comparison between AC concentrations in T0 and Tend samples. (right) Comparison between
AC concentrations within the the Tend samples.
From the bar chart we can see, as expected, that the AC concentration in the T0 samples is
greater than that of the Mya, Macoma, and microbial degradation samples. It should be noted
that the amount of AC present in the T0 samples is slightly lower (avg. 38!g/g dw sediment)
than the nominal concentration of AC in the sediment (50!g/g dw sediment). As for the
Control samples, no trace of AC has been detected.
According to Levene’s Homogeneity Test (table 6), the data obtained is evenly distributed,
with a p-value of p = 0.078.
Table 6. Homogeneity of variances
Levene's Test for Homogeneity of
Variances
Test Statistic p-Value
Based on Mean 3.314 0.078
Based on Median 0.459 0.719
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We proceeded by presuming that the alternative hypothesis is accepted. By running the
General Linear Model test on the T0, Macoma AC, and Mya AC groups, a p-value of p =
0.000 was obtained (see table 7). This means that there is a significant difference between the
AC level in the T0 samples and the one from the other samples (p<0.05).
Table 7. ANOVA results
Analysis of Variance
Source Type III SSdfMean SquaresF-Ratiop-Value
TREATMENT$465.346 3 155.115 25.939 0.000
Error 47.840 8 5.980
To further test which of the samples are different (or if all the samples are different) from the
T0 sample, the Tukey HDS test was performed. From the results presented in table 8, we can
observe that the AC concentration in T0 is significantly different from that of the Macoma AC
(p = 0.000), Mya AC (p = 0.000), and microbial degradation AC (p = 0.001) samples. On the
other hand, when compared among each other, the end samples (Tend) did not show a
significant difference among AC levels: Macoma AC vs Mya AC – p = 0.980, Macoma AC
vs microbial degradation AC – p = 0.971, and Mya AC vs microbial degradation AC – p =
1.000.
Table 8. Results obtained from the Tukey Test.
Tukey's Honestly-Significant-Difference Test
TREATMENT$(i)TREATMENT$(j)Differencep-Value95% Confidence Interval
Lower Upper
Mac ac Mya ac -0.763 0.980 -7.157 5.631
Mac ac Micro degr ac -0.869 0.971 -7.264 5.525
Mac ac T0 initial ac -14.905 0.000 -21.299 -8.510
Mya ac Micro degr ac -0.107 1.000 -6.501 6.288
Mya ac T0 initial ac -14.142 0.000 -20.536 -7.747
Micro degr ac T0 initial ac -14.035 0.001 -20.429 -7.641
ACETYL CEDRENE IN TISSUE
Traces of AC have been found in the Macoma samples treated with AC, with a value of
92!g/g for replicate 1, and 76!g/g for replicate 2. These results were displayed in the form of
a small peak on the mass-spectrum graph. Even though the peaks themself were under the
3xbackground noise value needed for qualifying the samples, we proceeded in determining
the AC concentration. We decided to do this as none of the other samples showed a similar
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trend (thus we can exclude the possibility of contamination from other samples).
No traced of AC were detected in any of the Mya samples.
Figure 19. AC peak on the mass-spectrum in the Macoma AC 2 sample.
ACETYL CEDRENE IN WATER
No detectable traces of AC have been found in the water phase of the samples.
7. DISCUSSION
7.1 EFFECTS OF ACETYL CEDRENE
During the experimental period, both burrowing behavior and mortality have been monitored.
From the mortality graphs presented in section 6.1 (figure 10 and 11), we could observe that
several organisms from both the Mya and Macoma samples have died. This was a trend that
was not expected, as the concentration chosen for AC was not high enough to be considered
lethal. We believe that the mortality might not be due to the presence of AC, as both the
Control and AC treated samples of each of the test organisms have a similar number of dead
organisms (i.e. 5 organisms in Control and 5 in AC treated samples for Mya; 3 in Control and
4 in AC treated samples for Macoma).
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From the graphs we can also see that M. arenaria began dying earlier in the exposure period
(day 2) compared to M. balthica (day 5). Also, by the end of the experiment, a larger number
of Myas (10 in total) was reported dead, compared to Macoma (7 in total).
We presume that the reason why some of the organisms died was because of handling and
constant stress brought to their environment (e.g. acclimatization, frequent movement of the
organisms, defective air pumps). Another explanation for the increasing numbers of dead
organisms per beaker might be that once one of the organisms died, decomposing organic
matter was released, hence contaminating the water and making the other organisms more
susceptible to dying.
If multiple toxic compounds are present in the environment, the toxicity of the mixture will
approximately sum up the values of toxicity of the individual components (Walker et. al.,
2006). This means that every individual chemical would roughly have the same toxicity when
measured in a mixture or measured alone. The concentration of each of the chemicals that
take part in a mixture dictates the levels of toxicity that each of the chemicals will have. This
information might be relevant to our study because we do not know if the sediment used for
the experiment set-up was contaminated with any other compounds. Thus, if any other toxic
compound was present in the sediment, it could explain why organisms from both the Control
and AC treatment groups died.
When observing the burrowing behavior, two different trends were noticed, a stable
burrowing behavior for Macoma and a fluctuating one for Mya.
M. balthica behaved as expected, burrowing in the sediment by the end of the first day, both
in the Control and treatment group (see section 6.1, figure 12 and 13). This is generally a sign
of good fitness. If comparing the Control group to the AC treated one, it can be seen that most
of the organisms in the Control were fully burrow within half an hour, whereas it took an
entire day for the organisms in the treatment group to do the same. This might be because
they sensed the presence of AC and it took time for them to adjust to the new environment.
Also, the number of organisms that did not fully burrow (halfway in) or not burrow at all (out)
was slightly higher in the AC treated group compared to the Control group. This might also be
due to the presence of AC in the former.
M. arenaria’s burrowing behavior shows a totally different distribution pattern, as the data is
more chaotically dispersed. This fluctuation in burrowing behavior numbers seen in the first
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half of the graphs (for both the Control and AC samples) might be explained by the fact that
the monitoring was performed by different people in different days. No specific method of
assessing the burrowing behavior was established. Thus, what one person might have noted
down as halfway in the sediment, another might have perceived as out of the sediment (the
same applies for burrowed vs halfway burrowed). The way in which a person saw in what
state the organisms were was especially affected by the angle from which the observer looked
at them (see figure 20). However, it might be argued that if this was the case, why didn’t the
same pattern appear in the Macoma samples as well. In the case of Macoma, it was easy to
say, without any problem, if the organism was inside, halfway, or outside of the sediment.
However, Mya was more problematic as one could not be always sure of the actual position in
which they were (the delimitations between in/halfway and halfway/out, were hard to
establish). When looking at the second half of the two graphs, the fluctuation in patterns was
also a result of mortality.
Figure 20. The burrowing behavior results might be slightly
biased by the angle at which the observation was made (i.e.
viewing the organisms from atop of the beaker or from side-
view through the glass).
Research states that M. arenaria has greater difficulty in reburrowing after disturbances. This
is due to the size its foot, which remains the same as the clam grows, therefore the older the
clam, the less successful it is at re-burrowing (Checa & Cadee, 1997; Pfitzenmeyer &
Drobeck, 1967). In our experiment this could imply that the larger organisms were not able to
burrow. If the clam was placed horizontally, it might have difficulties to turn itself vertically
and commence burrowing.
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7.2 FATE OF ACETYL CEDRENE
When assessing the concentration level of AC in the T0 sample, it was observed that the initial
concentration was lower than expected (~38!g/g dw sediment, instead of the aimed value of
50!g/g dw sediment). This might be due to loss during handling, evaporation from the system,
and degradation mediated by microbes.
From the results obtained from the one-way ANOVA, we can see that there is a significant
difference between the AC concentration of the T0 sample and that of the microbial
degradation sample (p = 0.000). We believe that this is mainly a result of microbial activity.
When comparing the AC level of the microbial degradation samples to that of the Macoma
AC and Mya AC samples, the statistical data showed that there was no significant difference
(microbial degradation vs Macoma, p = 0.971; microbial degradation vs Mya, p = 1.000).
This implies that the two test organisms were not efficient at taking up and metabolizing AC.
Furthermore these results show that the movement of the organisms in the sediment had no
effect on microbial degradation.
We were expecting to see a lower level of AC in the samples containing M. balthica, due to
its feeding strategy and because the water was filtered, forcing Macoma to obtain its nutrients
solely from the sediment.
Traces of AC have been found in the tissue of the organism, suggesting that Macoma did take
up the contaminant from the sediment. The actual concentration of the xenobiotic in the tissue
was higher than the initial AC concentration added to the system. Since this did not
significantly affect the overall concentration present in the sediment, we could presume that
the organism was accumulating and storing it, but the rate at which they did so was too slow
to have an impact. This could be supported by research on M. balthica with respect to other
organic contaminants. For example, it has been shown that Macoma is efficient in
accumulating PAHs, but not biortansforming them (Rust et. al., 2004).
As for Mya arenaria, it was expected that it would be less efficient at taking up AC from the
sediment, due to its suspension-feeding habits. In general, Mya has been shown to be capable
of metabolizing some PAHs (e.g. benzo[∝]pyrene) at a higher rate than M. balthica, however
this doesn’t seem to be the case with AC.
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8. CONCLUSION
From the result obtained from ANOVA, we could conclude that the alternative hypothesis is
accepted because there is a significant difference between the T0 samples and the Macoma
AC and Mya AC samples (T0 vs Macoma AC, T0 vs Mya AC, p = 0.000). However, because
the microbial degradation was not significantly different when compared to the samples with
organisms, we can safely state that any difference in AC concentration detected in the
Macoma and Mya samples was due to the presence of microbial degradation. Thus, we have
to reject our alternative hypothesis and accept the null hypothesis; the presence of Macoma
balthica and Mya arenaria does not affect the fate of AC, but microbial degradation does.
Since there is no significant difference between the amount of AC found in the Macoma and
Mya samples, we can not state which of them has the greatest impact on AC, or if there is any
impact at all.
When looking at the effect of sediment-associated AC on the test organisms, the mortality
graphs provide no evidence that mortality was caused by AC. As for the burrowing behavior,
we believe that the organisms were aware of its presence, and therefore they were not
particularly keen to burrow (at least in the case of Mya). It should be also mentioned that the
AC ingested by Macoma might have had an effect on the actual organisms, but we were not
able to tell how exactly they were affected.
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9. APPENDICES
9.1 APPENDIX A – dw:ww measurements
Table 9. dw:ww measurements for determining the amount of sediment needed for experimental set-up.
Aluminum boat - WW
(g)
WW sediment (g)
Aluminum boat –
DW (g)
DW sediment (g)
7,3448 5,6864 5,9651 4,3067
10,3840 8,7218 8,2511 6,5889
5,3954 3,7315 4,4989 2,8351
Table 10. Measurements for dw:ww
AC TREATMENT
Aluminum
tray (g)
Sediment –
wet weight (g)
Sediment + tray –
dry weight (g)
Sediment –
dry weight (g)
Mac 1 1.6653 2.1590 3.2652 1.5999
Mac 2 1.6067 2.1118 3.2152 1.6085
Mac 3 1.6168 2.1509 3.2340 1.6172
Mya 1 1.6051 2.1212 3.1968 1.5917
Mya 2 1.6186 2.1324 3.2447 1.6261
Mya 3 1.6103 2.1303 3.2436 1.6333
Micro. degr. 1 1.6087 2.1030 3.1896 1.5809
Micro. degr. 2 1.6075 2.1440 3.2586 1.6511
Micro. degr. 3 1.6140 2.1305 3.2463 1.6323
NO AC TREATMENT
Mac 1 1.6300 2.0730 3.2231 1.5931
Mac 2 1.6180 2.0840 3.1949 1.5769
Mac 3 1.6156 2.0580 3.1948 1.5792
Mya 1 1.6062 2.1601 3.2653 1.6591
Mya 2 1.6040 2.1560 3.2580 1.6540
Mya 3 1.5990 2.1445 3.2167 1.6177
No organisms 1 1.6054 2.0517 3.1749 1.5695
T0 SAMPLES (AC TREATMENT)
T0 1 1.6060 3.7511 4,4629 2.8569
T0 2 1.6129 2.8668 3,8033 2.1904
T0 3 1.6010 3.2387 4,1359 2.5349
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9.2 APPENDIX B – Burrowing behavior exhibited over a 14-day period
%% Mya"AC% Mya"Control%
Time/beaker%no.% 1% 2% 3% 1% 2% 3%
after"1/2h" 1i,%2h,%1o% 2i,%2o% 1i,%2h,%1o% 1i,%3h% 1i,%1h,%2o% 1i,%3o%
after"1h" 2i,%2h% 1i,%3o% 2i,%2o% 2i,%1h,%1o% 2i,%1h,%1o% 1i,%3o%
after"8h" 2i,%2h% 2i,%2o% 2i,%1h,%1o% 2i,%1h,%1o% 2i,%2o% 2i,%1h,%1o%
26.03.%Tue% 2i,%2h% 2h,%2o% 2i,%1h,%1o% 2i,%1h,%1o% 2i,%2o% 2i,%1h,%1o%
27.03.%Wed% 4h% 2h,%2o% 2i,%1h,%1o% 2i,%1h,%1d% 1i,%1h,%2o% 2i,%2o%
28.03.%Thu% 4h% 3h,%1o% 2i,%1h,%1o% 1i,%2h,%1d% 1i,%1h,%2o% 1i,%2h,%1o%
29.03.%Fri% 2i,%2h% 4h% 2i,%1h,%1o% 1i,%2h,%1d% 1i,%1h,%2o% 1i,%1h,%2o%
30.03.%Sat% 4h% 4h% 2i,%1h,%1d% 3o,%1d% 1i,%3o% 4o%
31.03.%Sun% 4h% 4h% 2i,%1h,%1d% 3o,%1d% 1i,%3o% 4o%
01.04.%Mon% 1h,%3d% 4h% 2i,%1o,%1d% %%%%%3o,%1d"% 2i,%2o% 4o%
02.04.%Tue% 1h,%3d% 4h% 2i,%1o,%1d% 3o,%1d% 1i,%2o,%1d% 3o,%1d%
03.04.%Wed% 1h,%3d% 4h% 2i,%1o,%1d% 3o,%1d% 1i,%2o,%1d% 3o,%1d%
04.04.%Thu% 1h,%3d% 4h% 2i,%1o,%1d% 1h,%2o,%1d% 1i,%2o,%1d% 3o,%1d%
05.04.%Fri% 1h,%3d% 3h,%1d% 2i,%1o,%1d% 1h,%2o,%1d% 1i,%2o,%1d% 3o,%1d%
06.04.%Sat% 1o,"3d% 2h,%1o,%1d% 2i,%1o,%1d% 1h,%2o,%1d% 1h,%1o,%2d% 3o,"1d"%
07.04.%Sun% 1o,%3d% 2h,%1o,"1d% 1h,%2o,%1d% 1h%2o,%1d% 1h,%1o,%2d% 3o,%1d%
08.04.%Mon% 1o,%3d% 1h,%2o,%1d% 1h,%2o,%1d% 1h,%2o,%1d% 1h,%1o,%2d% 1h,%2o,%1d%
Dissection% % 1d" " 1d" " 1d"
LEFT% 1" 2"" 3" 2" 2" 2"
! Mac"AC" Mac"Control"
Time/beaker%no.% 1" 2" 3" 1" 2" 3"
after"1/2h! 2i,%2h" 2i,%2o" 1i,%3h" 3i,%1h" 3i,%1o" 2i,%2o"
after"1h! 2i,%2h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1o" 2i,%2o"
after"8h! 2i,%2h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1o" 2i,%2o"
26.03.%Tue% 3i,%1h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1o" 2i,%2o"
27.03%Wed% 3i,%1h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1o" 2i,%2o"
28.03%Thu% 3i,%1h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1o" 2i,%2o"
29.03%Fri% 3i,%1h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1h" 2i,%2o"
30.03%Sat% 3i,%1h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1d" 2i,%2o"
31.03%Sun% 3i,%1h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1d" 2i,%2o"
01.04%Mon% 3i,%1h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1d" 2i,%2o"
02.04%Tue% 3i,%1h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1d" 2i,%2o"
03.04%Wed% 3i,%1h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1d" 2i,%2o"
04.04%Thu% 3i,%1d" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1d" 2i,%2o"
05.04%Fri% 3i,%1d" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1d" 2i,%1o,%1d"
06.04%Sat% 3i,%1d" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1d" 2i,%1o,%1d"
07.04%Sun% 2i,%2d" 1i,%2o,%1d" 3i,%1h" 3i,%1h" 3i,%1d" 2i,%1o,%1d"
08.04%Mon% 1i,%1h,%2d" 1h,%1o,%2d" 3i,%1h" 3i,%1h" 2h,%1o,%1d" 1h,%1o,%2d"
Dissection% 1d" " " " " "
LEFT% 1" 2" 4" 4" 3" 2"
Legend:" i%=%inside,%h%=%halfway,%o%=%out%(of%sediment),%d%=%dead%
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9.3 APPENDIX C – Water volume in samples (from overlaying water)
Table 11. A. Overlaying water volume from the AC treatment
AC Treatment
Time Organisms (beaker nr.) Overlaying water (ml)
15:02 Mya (1) 130
Mya (2) 130
Mya (3) 130
15:18 Macoma (1) 130
Macoma (2) 130
Macoma (3) 130
15:53 Microbial degradation (1) 140
Microbial degradation (2) 130
Microbial degradation (3) 130
Table 11. B. Overlaying water volume from the Control samples
CONTROL
Time Organisms (beaker nr.) Overlaying water (ml)
14:32 – 14:54
Mya (1) 130
Mya (2) 140
Mya (3) 130
14:08 – 14.29
Macoma (1) 130
Macoma (2)* 140
Macoma (3) 130
14:00
No organisms (1) 140
No organisms (2) 100
No organisms (3) 140
*in the Macoma (2) beaker, there were fine particles of sediment suspended in the water
column.
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9.4 APPENDIX D - Laboratory Techniques: The ASE Machine: Accelerated Solvent
Extractor
Accelerated Solvent Extraction (ASE) is a method used for the extraction of test compounds
from soil or other solid matrices. The process itself is fully automated.
The machine is made up of a static part (consisting of the Electronics Area, Oven Area, and
the Solvent Reservoir Compartment) and a mobile part (consisting of the Needle Mechanism,
the Cell Tray – where the cells are loaded –, and the Vial Tray – where the glass-vials are
positioned –). The Cell Tray can support a number of 24 cells and 4 rinse-tubes, while the
Vial Tray can support 26 vials (60ml, clear glass) and 4 rinse-vials (60ml, amber glass)(vial
type: EPA-type VOA) (DIONEX, 1999).
Figure 21. ASE machine components (image source: DIONEX, 1999)
Prior to using the ASE machine, the Dichloromethane is placed on an ice bath to avoid the
formation of bubbles (Dichloromethane has a low boiling point) and the Nitrogen pump is
turned on. As mention earlier in the report, the program selected for the ASE machine was:
a. Preheat (0 min)
b. Heat (5 min)
c. Static (15 min)
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d. Flush (50 vol)
e. Purge (60 sec)
f. Cycles (2)
g. Pressure (2000 psi)
h. Temperature (60℃)
i. Solvent (Dichloromethane, 100%)
Before running any of the loaded cells, the machine will first rinse itself with
Dichloromethane and deposit the waste into the amber rinse-vials. After this step, the samples
are processed.
The standard procedure for running a sample-cell consists of preparing the cells and loading
them on the Cell Tray (the same is done with the glass-vials). Once the machine is started, the
cells and glass vials are rotated to the initial positions specified by the running method. The
machine’s needle then perforates the glass-vial corresponding to the processed cell. The cell is
picked-up and moved to the oven. Dichloromethane is then used to wash the cell. The next
step consists of heating the cell up to 60℃ (so the cell reaches thermal equilibrium) and
pressurizing it to 2000 psi. Static extraction then takes place, after which the contents of the
cell are re-washed with fresh solvent. As Dichloromethane passes through the sample, it
attaches to and collects the chemicals of interest, washing them into the glass vials situated on
the Vial Tray. The process ends with the unloading of the cell.
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9.5 APPENDIX E - Sample preparation for ASE
Table 12. ASE guideline. This table records the amount of sediment and hydromatrix used for
each sample per ASE cell. The far right column illustrates the number of sample corresponding
to each position on the ASE machine.
AC TREATMENT
Sediment
(g)
Hydromatrix
(g)
Corresponding cell
(nr.)/(ASE nr.)
Mac 1 5.79 5.05 1%(2)
Mac 2 5.34 5.02 2%(3)
Mac 3 5.11 5.12 3%(4)
Mya 1 5.04 5.10 4%(5)
Mya 2 5.74 4.99 5%(6)
Mya 3 5.73 5.00 6%(7)
Micro. degr. 1 5.72 5.00 7%(8)
Micro. degr. 2 5.51 4.97 8%(9)
Micro. degr. 3 5.67 5.03 9%(10)
NO AC TREATMENT
Mac 1 5.23 5.02 10%(11)
Mac 2 5.16 5.08 11%(12)
Mac 3 5.04 5.14 12*(13)
Mya 1 5.69 5.03 13%(14)
Mya 2 5.28 5.04 14%(15)
Mya 3 5.15 5.13 15%(16)
No organisms 1 5.61 5.20 20%(1)
T0 SAMPLE
T0 1 5.3260% 5.0094% 22%
T0 2 5.1060% 5.0677% 23%
T0 3 5.1855% 5.0531% 24%
*cell nr 12 (Mac 3) – the internal standard was added twice (200 µl instead of 100 µl)
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9.6 APPENDIX F - Laboratory Techniques: The GC-MS Machine
The Gas Chromatography – Mass Spectrometer (GC-MS) instrument is used for separating
chemicals based on the ease with which they evaporate into a gas (change state from liquid to
gas), and identifying them based on the structure they possess.
The instrument is composed of two parts: the gas chromatography (GC) part that separates the
chemical compounds into pulses of pure chemicals, and the mass spectrometer (MS) part that
is used for identifying and quantifying the chemicals (OSU, 2013).
Figure 22. The different components of the GC-MS machine
The Gas chromatography unit of the machine is made up of three parts:
- Injector – extracts the solvent from the GC-MS-vials and sends it to the GC. The needle of
the injector extracts one microliter (1 !l) of the compound and injects in the GC from where
the sample is propagated further by a non-reactive gas. The injector can be heated up to a
temperature of 300℃ to change the phase of the solvent from liquid to gas.
- Oven – represents the outer part of the GC unit. It contains the column, which is heated to
enable the molecules of the analyzed chemicals to move through it. The oven can normally
reach temperatures from 40℃ to 320℃ (OSU, 2013).
- Column – is situated inside the oven and consists of a thin tube of varying lengths and
thicknesses that is coated on the inside with a special polymer (polymer coating, length and
52"|"P a g e "
%
thickness depend on the type of chemical analyzed). The chemicals that undergo analysis are
separated based on their volatility and are transported through the column with the help of the
non-reactive gas. Chemicals that have high volatility propagate faster through the column than
the ones that are characterized by low volatility (OSU, 2013). The volatility of any given
substance is linked to the size of its molecules, as small molecules tend to propagate at higher
speeds compared to larger molecules.
The Mass Spectrometer unit consists of:
- Ion source – once the chemical analyzed has passed through the GC, the resulting pulses go
to the MS unit. The molecules are then broken into pieces, as they are blasted with electrons.
This determines the molecules to lose, themselves, electrons and become positively charged
particles (ions). These charged particles then continue their way to the filter.
- Filter – the charged particles then pass through an electromagnetic field that uses the mass
of the ions as a base for filtration. The desired range of masses (that will be able to pass
through the filter) is chosen prior to the commencement of analysis.
- Detector – quantifies the ions with the desired mass (target ions) and sends the collected
information to a computer, which reinterprets it in the form of a mass spectrum. The mass
spectrum is illustrated in the form of a graph that consists of a number of ions of different
masses that have passed through the filter.
53"|"P a g e "
%
9.7 Appendix G – Overall results
Table 13. Overall results. From left to right: Treatment type, Initial AC concentration (added in the sediment),
Measured AC concentration (at the end of the exposure period), Calculated AC concentration (based on dw),
Dry weight, Wet weight, dw:ww ratio, Amount of sediment measured used for analysis (ww), Amount of
sediment used for analysis (dw)
Figure 23. Additional General Linear Model graphs: (left) Overall view of the To vs Tend samples; (right)
Comparison between Tend samples.
54"|"P a g e "
%
10. REFERENCE LIST
%
Atchison, G. J., Sandheinrich, M. B., and Bryan, M. D., (1996) A review of the effects of
pollution on the behaviour of aquatic animals;
Barnes, R. S. K., (1994) The brackish-water fauna of northwestern Europe, Cambridge
University Press;
Benn, F. R. & McAuliffe, C. A., (1975) Chemistry and Pollution, London, Macmillan.
Cammen, L. M., (1980) Ingestion Rate: An Empirical Model for Aquatic Deposit Feeders and
Detritivores, Department of Zoology, North Carolina State University, Raleigh, North
CaroIina 27650 USA, Oecologia (Berl.) 44: 303-310;
Checa, A. G., & Cadee, G. C., (1997) Hydraulic burrowing in the bivalve Mya arenaria
Linnaeus (Myoidea) and associated ligamental adaptations, Journal of Molluscan Studies, 63:
157-171;
Dai, L., Selck, H., Salvito, D., and Forbes, V. E., (2012) Fate and effects of sediment-
associated acetyl cedrene in sediments inhabited by the deposit feeder, Capitella teleta,
Environmental Toxicology and Chemistry, 31: 2639-2646;
de Goeij, P. & Luttikhuizen, P., (1998) Deep-burying reduces growth in intertidal bivalves:
field and mesocosm experiments with Macoma balthica, Journal of Experimental Marine
Biology and Ecology, Issue 2, 228: 327-337;
Decho, A.W., & Luoma, S.N., (1991) Time-courses in the retention of food material in the
bivalves Potamocorbula amurensis and Macoma balthica: significance to the absorption of
carbon and chromium, Mar. Ecol. Prog. Ser, 78: 303-314;
DIONEX, (1999) ASE 200 Accelerated Solvent Extractor – Operator’s Manual;
Jørgensen, A, Rasmussen, L. J., Andersen, O., (2005) Characterisation of two novel CYP4
genes from the marine polychaete Neries virens and their involvement in pyrene hydroxylase
activity. Biochemical and Biophysical Research Communications, 336: 890–897;
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%
Kannan, K., Reiner, J. L., Yun, S. H., Perrotta, E. E., Tao, L., Jhonson – Restrepo, B., Rodan,
B. D., (2005) Polyciclyc musk compounds in higher trophic level aquatic organisms and
humans from the United States, Chemosphere, 61: 693-700;
Klaschka, U., Carsten, P., von der Ohe, Bschorer, A., Krezmer, S., Sengl, M., and Letzel, M,
(2013) Occurrences and potential risks of 16 fragrances in five German sewage treatment
plants and their receiving waters, Environ Sci Pollut Res, 20: 2456–2471;
Kristensen, K., (2000) Organic matter diagenesis at the oxic/anoxic interface in coastal marine
sediments, with emphasis on the role of burrowing animals, Hydrobiologia, 426: 1–24;
Køie M., Kristiansen A., and Weitemeyer, S. (2000) Havets dyr og planter, GADs Forlag;
Landis, W. G. & Yu, M. H., (1999) Introduction to Environmental Toxicology, 2nd
Edition,
CRC Press;
Lin, J., & Hines, A. H., (1994) Effects of Suspended Food Availability on the Feeding Mode
and Burial Depth of the Baltic Clam, Macoma balthica, Oikos, Fasc. 1 (Feb., 1994), 69: 28-
36;
Möller, P. & Rosenberg, R. (1983) Recruitment, abundance and production of Mya arenaria
and Cardium edule in marine shallow waters, Western Sweden, Ophelia, vol. 22, Issue 1, 33-
55;
Olafsson, E. B., (1986) Density Dependence in Suspension-Feeding and Deposit-Feeding
Populations of the Bivalve Macoma balthica: A Field Experiment, Journal of Animal
Ecology, 55: 517-526;
OSU (Oregon State University), 2013, GCMS – How does it work?
http://www.unsolvedmysteries.oregonstate.edu/MS_05 (last accessed on 12.05.13);
Pfitzenmeyer, H. T., & Drobeck, K. G., (1967) Some factors influencing reburrowing activity
of soft shell clam, Mya arenaria, Chesapeake Science, 8: 193-199;
Phelps, H. L., (1989) Clam Burrowing Bioassay for Estuarine Sediment, Bull. Environ.
Contam. Toxicol, 43: 838-845;
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pollutants in soils and sediments - a perspective on mechanisms, consequences and
assessment, Environmental Pollution, 108: 103-112;
56"|"P a g e "
%
Rimkus, G. G., (1999) Polycyclic musk fragrances in the aquatic environment, Eoxicol Lett
111: 37-56;
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metabolism and bioaccumulation of benzo(a)pyrene in benthic invertebrates, Environmental
Toxicology and Chemistry, 23: 2587–2593
Selck, H., (2002) Interactions among contaminant exposure route, kinetics and toxicity in
marine deposit-feeders, PhD Thesis, Roskilde University, DK;
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organic contaminants in soils: fundamental concepts and techniques for analysis, European
Journal of Soil Science, 54: 809–818;
Simonich, S. L., Begley, W. M., Debaere, G., and Eckhoff, W. S., (2000) Trace analysis of
fragrance materials in wastewater and treated wastewater, Environ Sci Technol, 34: 956-965;
Simonich, S. L., Federle, T. W., Eckhoff, W. S., Rottoers, A., Webb, S., Sabaliunas, D., and
De Wolf, W., (2002) Removal of fragrance materials during U.S. and European wastewater
treatment, Environ Sci Technol, 36: 2839-2847;
Spacie, A., & Hamelink, J. L., (1995) Bioaccumulation, in Rand, G. M., Fundamentals of
Aquatic Toxicology: Effects, Environmental Fate, and Risk Assessment, CRC Press, Boca
Raton, FL, USA, 493-521;
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sediment type, hypoxia and predator presence, Marine Ecology Progress Series, 212: 183–
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Ecotoxicology, 3rd
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Bachelor Thesis cut

  • 1. FATE OF THE FRAGRANCE MATERIAL ACETYL CEDRENE IN SEDIMENTS INHABITED BY THE BENTHIC MOLLUSCS MACOMA BALTHICA AND MYA ARENARIA Kaushal BARAL**, Valentina BURDUKOVSKA*, Minodora DAVID*, Mads KÆRHUS OLUFSEN* Bachelor project*/Semester project** Spring 2013 Supervisor: Prof. Henriette SELCK Dept. ENSPAC Roskilde University Denmark
  • 2. 2"|"P a g e " % Cover picture: a) Balanidae, b) Mytilus edulis, c) Lanice conchilega, d) Lagis koreni, e) Littorina littorea, f) Ensis americanus, g) Cerastoderma edule, h) Scrobicularia plana, i) Mya arenaria, k) Arenicola marina, l) Hediste diversicolor, m) Macoma balthica. (image source: Senckenberg: World of Biodiversity)
  • 3. 3"|"P a g e " % ACKNOWLEDGEMENT We would like to express our gratitude for all those who helped us in realizing this project. Firstly, we would like to thank Lina Dai for providing the basis for our report and guiding us throughout the process. We would also like to thank prof. Gary Banta, ENSPAC for helping us identify and acclimatize the test organisms, and the technicians Anne-Grete Winding, Klara Jensen, May-Britt Kary, for helping in the field work and getting us acquainted with the laboratory equipment. Last, but not least, we would like to thank our supervisor, prof. Henriette Selck, for all her dedication and advice.
  • 4. 4"|"P a g e " % ABSTRACT In recent time it has come to concern that hydrophobic organic compounds, from the relatively large group of fragrance materials, enter the aquatic environment via drainage systems and bioaccumulate in the sediment and biota. Acetyl cedrene is one of these compounds. In this report the fate and effects of acetyl cedrene were studied on two species of marine molluscs – Macoma balthica and Mya arenaria – with different feeding strategies. An experiment was conducted over a period of 14 days, after which the concentrations of acetyl cedrene present in different compartments (sediment, water, and tissue) were analyzed with a GC-MS machine. The results were statistically tested with a General Linear Model and a One- Way ANOVA. The outcome suggested that the actual organisms were not efficient enough in biotransforming the fragrance material. Additionally, the effects of acetyl cedrene on the studied species were expressed as a delay in burrowing behavior. Mortality has been recorded among the test organisms, but it was not a result of the presence of acetyl cedrene.
  • 5. 5"|"P a g e " % TABLE OF CONTENTS% 1."INTRODUCTION".............................................................................................................."6% 1.1"AIM"OF"REPORT"....................................................................................................................."7% 1.2"HYPOTHESIS"..........................................................................................................................."7% 2."ACETYL"CEDRENE"............................................................................................................"8% 2.1"PHYSICAL"AND"CHEMICAL"PROPERTIES".................................................................................."8% 2.2"ROUTES"OF"ENTERING"THE"ECOSYSTEM"................................................................................."9% 2.3"UPTAKE"ROUTES"BY"AQUATIC"ORGANISMS"............................................................................"9% 3."CHOICE"OF"TEST"ORGANISMS"......................................................................................."11% 3.1"MYA"ARENARIA"..................................................................................................................."11% 3.2"MACOMA"BALTHICA"............................................................................................................"12% 4."BIOACCUMULATION"AND"BIOTRANSFORMATION"........................................................"13% 4.1"BIOAVAILABILITY"................................................................................................................."13% 4.2"BIOTRANSFORMATION"........................................................................................................"15% 5."MATERIALS"AND"METHODS".........................................................................................."16% 5.1"SEDIMENT:"COLLECTION"AND"HANDLING"............................................................................."16% 5.2"SEDIMENT"SPIKING"WITH"ACETYL"CEDRENE"........................................................................."17% 5.3"TEST"ORGANISMS:"COLLECTION"AND"HANDLING".................................................................."19% 5.4"EXPERIMENT"SETFUP"............................................................................................................"20% 5.5."BURROWING"BEHAVIOR"....................................................................................................."22% 5.6"WATER,"TISSUE,"AND"SEDIMENT"ANALYSIS".........................................................................."22% 5.7"GCFMS"ANALYSIS".................................................................................................................."27% 5.8"STATISTICAL"METHODS"........................................................................................................"30% 6."RESULTS"......................................................................................................................."31% 6.1"EFFECTS"ON"ORGANISMS"....................................................................................................."31% 6.2"FATE"OF"AC".........................................................................................................................."36% 7."DISCUSSION"................................................................................................................."40% 7.1"EFFECTS"OF"ACETYL"CEDRENE"..............................................................................................."40% 7.2"FATE"OF"ACETYL"CEDRENE"...................................................................................................."43% 8."CONCLUSION"................................................................................................................"44% 9."APPENDICES"................................................................................................................."45% 9.1"APPENDIX"A"–"dw:ww"measurements".................................................................................."45% 9.2"APPENDIX"B"–"Burrowing"behavior"exhibited"over"a"14Fday"period"......................................"46% 9.3"APPENDIX"C"–"Water"volume"in"samples"(from"overlaying"water)"........................................"47% 9.4"APPENDIX"D"F"Laboratory"Techniques:"The"ASE"Machine:"Accelerated"Solvent"Extractor"......"48% 9.5"APPENDIX"E"F"Sample"preparation"for"ASE"............................................................................"50% 9.6"APPENDIX"F"F"Laboratory"Techniques:"The"GCFMS"Machine".................................................."51% 9.7"Appendix"G"–"Overall"results"................................................................................................"53% 10."REFERENCE"LIST".........................................................................................................."54%
  • 6. 6"|"P a g e " % 1. INTRODUCTION % Fragrance materials (FM), such as acetyl cedrene (AC), represent a large group of aromatic compounds with varying toxicities that can be normally found in household care products. They have been found both in the water and sediment compartments of wastewater, in the final stages of wastewater treatment (Simonich et. al., 2000). It is especially the lipophilic organic compounds that can pose a threat to benthic invertebrates because of their tendency to bioaccumulate in sediment. These hydrophobic contaminants bind to the sediment particles and can be taken up by deposit-feeding organisms that thrive on organic matter. So far, traces of FMs have been found in clams, mussels, fish, sharks, and other marine animals (Kannan et. al., 2005). Even though little is known about the toxicity of acetyl cedrene in the aquatic environment, it has been found to have a measurable concentration in sewage wastewater, it is highly accumulative in the sediment and has low water solubility (Simonich et. al., 2000). For these reasons, AC was chosen as the test compound of this report. The overall aim of the report is to assess the fate and effects of the sediment-bound fragrance material acetyl cedrene (AC) in the presence of the deposit-feeding mollusc Macoma balthica and the suspension-feeding mollusc Mya arenaria. The above-mentioned species were selected because of their high abundance in the local estuarine systems (Isefjord, Roskilde Fjord, Denmark), and their reported capability of bioaccumulating and biotransforming other organic pollutants (e.g. PAHs)(Rust et. al., 2004). Microbial degradation has also been used as a reference point to see to what extent AC is biodegraded in the absence of macrofauna. In order to do so, an experiment was set-up, and burrowing behaviour and AC degradation were used as indicators of the fate and effects of the contaminant. The article written by Dai et. al. (2012) was used as a point of departure for methods and experimental set-up.
  • 7. 7"|"P a g e " % 1.1 AIM OF REPORT In order to assess the fate and effects of the fragrance material acetyl cedrene, the following questions were addressed: 1) Does the presence of Macoma balthica and Mya arenaria affect the fate of sediment- associated AC? And if so, in what way is the fate of AC affected and which organism has the greater impact? 2) How does the sediment-associated AC affect the studied organisms? 1.2 HYPOTHESIS Before commencing the experiment, there were several aspects that were hypothesized on. Firstly, it was presumed that Macoma would show a greater impact on the fate of AC, because of its feeding strategy (deposit-feeder), compared to Mya, which was expected to have little impact (suspension-feeder). Secondly, it was presumed that no AC would be present in the water phase of the experiment - because of the low water solubility and sediment-binding properties of AC. And lastly, it was hypothesized that there will be a difference between the concentration of AC in the sediment measured at the beginning of the exposure period (T0) and the one measured at the end (Tend) (HA – AC conc. T0≠ AC conc. Tend), in other words, that the test organisms would affect the fate of AC by diminishing its concentration.
  • 8. 8"|"P a g e " % 2. ACETYL CEDRENE 2.1 PHYSICAL AND CHEMICAL PROPERTIES Acetyl cedrene (AC) is an organic compound widely used as a fragrance material (FM). FMs are aromatic compounds that are added to care products to give a pleasing scent. They can be characterized by the presence of aromatic rings and their volatility. These organic materials can be extracted from nature (plants, trees) or synthesized in the laboratory. The latter are extracted in the form of oils, concentrates or waxes by processes such as distillation, solvent extraction. Fragrance materials are usually synthetically derived as the alternative to macrocyclic compounds found in nature, which are relatively inexpensive compared to their natural counterparts (Rimkus, 1999). Because of the diversity of the physical and chemical characteristics of FMs, their ecotoxicity is variable, and their biodegradation rates can range from readily biodegradable to non-biodegradable (Simonich et al, 2000). Acetyl cedrene has similar chemical and physical characteristics to HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8- hexamethylcyclopenta-γ-2-benzopyran) and AHTN (7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4- tetrahydronaphthalene), synthetic musk fragrances recognized as significant contaminants of the aquatic environment, because of their lipophilic properties and persistent nature that has a tendency to bioaccumulate in fish and other organisms (Rimkus, 1999). AC tends to accumulate in sediment due to its high octanol-water partition coefficient (Log KOW=5.6–5.9) and low water solubility (1.28mg/L)(Simonich et al, 2000). Table. 1 General characteristics of acetyl cedrene Acetyl Cedrene (CAS 32388-55-9) Molecular Formula: C17H26O Octanol-Water Partition Coefficient (Log Kow): 5.6 - 5.9 Water solubility: 1.28 mg/L Vapor pressure: 0.058 Pa Boiling point: 272 °C Table 1 presents some additional information about the general properties of acetyl cedrene. Data related to the toxic or persistent nature of AC is scarcely available, thus more insight is needed concerning the fate and effects of this chemical in the aquatic environment.
  • 9. 9"|"P a g e " % 2.2 ROUTES OF ENTERING THE ECOSYSTEM When it comes to the chemicals found in household products, the main route of entering the ecosystem is by means of sewage water. The quality of sewage water that ends up in surface waters is closely linked to the raw sewage received, as well as the treatment applied (Benn & McAuliffe, 1975). Acetyl cedrene has been detected in the environment under varying concentrations. It has been found in concentrations of 7.15"±"4.32µg/L in European wastewater influents and 4.97"±"2.27µg/L in US wastewater influents, and in between 0.071- 0.270µg/L in several German wastewater effluents (Klaschka et. al., 2013; Simonich et. al, 2002). AC has also been found in biota, with concentrations ranging from <10–93µg/kg fresh weight in carp muscle tissue (Klaschka et. al., 2013). 2.3 UPTAKE ROUTES BY AQUATIC ORGANISMS There are multiple ways through which pollutants can enter an organism. For our test organisms the most relevant uptake routes are via the alimentary track and through respiratory surfaces. Thus, the pollutants can be taken up in the form of food and through ambient water (Walker et. al., 2006). If the organic pollutants are associated with particles (sediment or suspended particles), and taken up by the respiratory system, they could be deposited in the respiratory tract of the organisms. This is however a complex situation and as yet, the knowledge available on the matter is scarce (Walker et. al., 2006). A simplified model for the fate of a xenobiotic involves five types of sites: sites of uptake, metabolism, action, storage, and excretion (Walker et. al., 2006). Once a pollutant enters an organism, it can proceed towards the following sites and be treated in adequacy to their function within the organism: Sites of action. In such sites the toxic chemical interacts with the organism at a molecular or a structural level and the resulting activity resonates at the organism-level. In other words, the xenobiotic has a noticeable effect on the organism (Walker et. al., 2006). Sites of metabolism. In these types of sites, enzymes capable of metabolizing xenobiotics are acting upon the foreign chemicals, causing detoxification. Thus, the organism is acting upon the chemical (Walker et. al., 2006). This could be seen as a protection mechanism or as efficiency in chemical breakdown.
  • 10. 10"|"P a g e " % Sites of storage. In this case the xenobiotic is held in an inert state in which it does not act upon the organism, nor does the organism act upon it (Walker et. al., 2006). Sites of excretion. The result of excretion can be either the original chemical or a biotransformation product (Walker et. al., 2006). Figure 1. Simplified model of xenobiotic uptake and fate within an organism In the simple model illustrated in figure 1, the toxic chemicals are transported (after uptake) to the different compartments of the organism’s body. The movement of the xenobiotics into the organs and tissues could take place by diffusion through membranes, and in the case of lipophilic chemicals (such as AC) by lipid transport. If a compound is very lipophilic, it is transported by lipoproteins in a dissolved form. After their partial decomposition, the fragments of the lipoproteins are transported into cells and the bound lipophilic molecules are carried along. 2.4 EFFECTS ON BEHAVIOR Theoretically, all behaviours exhibited by an organism can be affected, to a certain extent, by xenobiotics. The article realized by Atchison et. al (1996) presents a review of the types of behaviours affected in aquatic animals. As noted here, there are three main types of behaviours that can be impaired: foraging, vigilance, and burrowing. Dysfunctional foraging behaviour leads to reduced resource uptake, which in turn can result in reduced production (e.g. nutrients, animal growth). Very little is known about how toxic compounds affect the appetite. As for food handling time (time spent from capture to ingestion), it has been shown that it is increased as a result of repetitive rejection and recapture (Atchison et. al., 1996).
  • 11. 11"|"P a g e " % If the vigilance behaviour is affected by the xenobiotic, the vulnerability to predators that the animal exhibits will increase. This can further lead to an increased mortality rate. Burrowing behaviour can also be affected in the presence of toxic contaminants. This is mostly exhibited as a refusal of the animal exposed to the toxin to burrow in the sediment, as it would otherwise do under normal living conditions. 3. CHOICE OF TEST ORGANISMS In this project we will investigate if the fragrance acetyl cedrene (AC) can be biotransformed by molluscs, and to do so we will look at two abundant benthic bivalves that both exhibit burrowing behavior but have different feeding strategies in the brackish waters of Roskilde Fjord. The organisms in this essay were chosen because of the close proximity to one of the major estuarine systems in Denmark, Isefjorden and Roskilde Fjord. Both organisms are widely abundant in coastal waters around the world, and are known to uptake and metabolize xenobiotics (Rust et. al., 2004). 3.1 MYA ARENARIA Easily recognized by its white elliptic shell with a grayish-brown periostracum, M. arenaria’s distinct feature consists of two merged siphons extruding at the posterior rounding of the shell (see figure 2). M. arenaria can grow up to 140 mm in length and have relatively large siphons compared to its body mass, which allows it to burrow up to 250 mm into to the sediment. This depends on the size of the individual, the larger the individual the deeper it can burrow (Wanink & Zwarts, 1989; Zaklan & Ydenberg, 1997). M. arenaria is a suspension feeder and is feeding strictly on the phytoplankton (maybe also other small particles) suspended in the water column and therefore has little to no uptake of sediment. These bivalves can be found in densities of up to 4000 individuals m-2 in estuarine areas with muddy sediment (Möller & Rosenberg, 1983). Figure 2. Mya arenaria. This mollusc burrows deep in the sediment, extruding its siphons to the surface of the sediment in order to feed (image source: Wheeler, J.).
  • 12. 12"|"P a g e " % 3.2 MACOMA BALTHICA This tellinid bivalve can be recognized by its triangular oval shell, which is smooth with a few concentric ridges and white, pinkish or orange in color (see figure 3, left). It can grow up to 35mm in length. The siphons of M. balthica are relatively long compared to the weight of the organism and allows it to burrow up to 80mm into the sediment depending on its size. The burrowing behavior of this species is also dependent on the seasonal change, as M. balthica burrows deeper into the sediment in the winter (Wanink & Zwarts, 1989). M. balthica can be found at densities of up to 1500 individuals m-2 (Olafsson, 1986). The feeding behavior of M. balthica both relies on suspension feeding and syphoning in the surface layer of the sediment, thereby both being a suspension and deposit feeder (see figure 3, right). In stagnant water M. balthica almost solely (95-99% of the time) uses the deposit feeding strategy (Olafsson, 1986). This choice of feeding behavior is also dependent on the availability of organic material in the water column (Lin & Hines, 1994). Lin and Hines also point out that the competition for food in the water column has a strong effect on the choice of feeding strategy of M. balthica, as the presence of high densities of other benthic organisms in the sediment lowers the amount of food in the water and thereby forces M. balthica to change to deposit- feeding. Figure 3. (left) Macoma balthica. This image clearly illustrates the organism’s siphons. (right) even though M. balthica mostly obtains its food through deposit-feeding, it can still change its strategy to suspension-feeding if competition for food is low (image source: de Goeij & Luttikhuizen, 1998).
  • 13. 13"|"P a g e " % As mentioned above, both molluscs exhibit burrowing behavior. The movements performed by the organisms while burrowing increase the oxygen availability in the sediment, which increases microbial degradation of organic compounds (Kristensen, 2000). Mya arenaria being the least mobile of the species should have the lowest impact on the sediment (Phelps, 1989). And Macoma balthica, which is known to move more around in the sediment, could have a larger impact on microbial biodegradation (Tallqvist, 2001). It has been shown that though M. arenaria is better at metabolizing PAHs than M. balthica, they are not as effective as other benthic species (Rust et. al., 2004). These results also suggest a high bioaccumulation potential of M. balthica as a low metabolic rate combined with a high rate of sediment ingestion and relatively long ingestion time compared to other bivalves could add to the bioaccumulation of PAHs through the food web (Cammen, 1980; Decho & Luoma, 1991). Bivalves have a 2-step uptake pathway; the first part involves extracellular digestion in the intestines and is not very effective for xenobiotic uptake, though research suggests that it differs from species to species (Decho & Luoma, 1991). The second pathway, involving intracellular digestion by the digestive glands shows a much higher absorption rate and takes much more time than the first one (Decho & Luoma, 1991). 4. BIOACCUMULATION AND BIOTRANSFORMATION Contaminants can accumulate in the body, tissue, and gut of organisms by means of adsorption, absorption, diffusion, exposure to a contaminant, or through the feeding habits of the organism. The substance is bioaccumulated when it is absorbed at a higher rate than it is excreted. 4.1 BIOAVAILABILITY - can be explained, as stated in Spacie’s article, as ‘the portion of the total quantity or concentration of a chemical in the environment or a portion of it that is potentially available for biological action, such as uptake by an aquatic organism’ (Spacie, 1995). In other words, bioavailability describes the amount of a compound that is available for uptake and biotransformation by an organism.
  • 14. 14"|"P a g e " % Figure 4. The amount of readily available xenobiotic decreases with time (image source: Semple et. al., 2003) Hydrophobic organic compounds like PAHs are believed to have a similar bioavailability pattern where bioavailability of the compound is lowered over time due to adsorption to and absorption in particles in the system. The fate of these compounds is usually divided into 2 main fractions; a readily available fraction which interacts with particles in the system via weak bonds and van der waal forces, and a more slowly absorbed recalcitrant fraction where covalent bonds and other more complex interactions are formed with organic particles in the sediment, thus making the compound less bioavailable (as this happens within several weeks it is not relevant in this work). When the compound is strongly bound to the sediment particles it becomes unavailable to the organism as the sediment particles are not degraded or destroyed by the organism, thus the particles are able to retain the compound and the particle bound compound is then excreted and returned to the sediment. As seen in figure 4, the more readily available fraction decreases with time as more strong bonds are formed and degradation takes place. The time in which these bonds are formed varies greatly dependent on mineral and organic content, temperature, pH, properties of the xenobiotic, size and surface area and structural/spatial complexity of particles in the sediment (Reid et. al., 2000; Semple et. al., 2003).
  • 15. 15"|"P a g e " % 4.2 BIOTRANSFORMATION Biotransformation, also known as xenobiotic metabolism, can be defined as the chemical process through which a xenobiotic is modified (broken down into simpler forms) by biologic entities (micro-organisms, plants, animals) in the presence or absence of oxygen (Walker et. al., 2006). This process often leads to a reduction in toxicity or to the transformation of the compound metabolised into a non-toxic form. There are also cases in which the toxicity of a xenobiotic can be enhanced or activated (Landis and Yu, 1999). A simplified model of this process is illustrated in figure 5. Figure 5. The different steps of biotransformation (image source: Walker et. al., 2006). Organic contaminants are likely to be biotransformed (once they are taken up by the organism) into a more water-soluble form is mediated by enzymes (Jørgensen et. al., 2005). The metabolism of most lipophilic xenobiotics takes place in two phases. The initial step of biotransformation, also called phase I, consists of processes such as oxidation (during which - COOH, -OH, -NH2, -SH can be added), hydrolysis, hydration, or reduction, and results in metabolites characterised by their hydroxyl groups (e.g. hydroxyl-PAHs or dihydrodiols). These hydroxyl groups will then be used during most of the following conjugation reactions that make up the second step of biotransformation (phase II). These metabolites are often more reactive compounds and are easily conjugated to more easily metabolized naturally occurring compounds such as sugar derivatives, peptides and sulphates (Selck, 2002). During phase II of PAH biodegradation, aqueous PAH-metabolites are produced (epoxides and phenol oxides, by means of conjugation) which are ionisable or more water soluble and can be readily excreted. (Jørgensen et. al., 2005). Figure 5 presents a simplified model of biotransformation.
  • 16. 16"|"P a g e " % 5. MATERIALS AND METHODS Both sediment and test organisms were collected from Roskilde Fjord (55°43'N, 11°58'E, Gershøj, Denmark) on the 27th of February, 2013. Since the amount of sediment collected proved to be insufficient, Isefjorden (55°67'N, 11°80'E, Munkholm, Denmark) was used as a second collection site (see figure 6). The ratio of the sediment from each of the two sources was roughly 0.5 and was mixed prior to the commencement of the experiment. Figure 6. Map of collection sites. The blue star represents the first collection poin, while the red star indicates the origin of the latter sediment collection. 5.1 SEDIMENT: COLLECTION AND HANDLING The sediment was collected, using a 500µm sieve, by scraping the surface of the sediment. Since the sediment surface was mostly covered my marine macroalgae, the sediment was collected from random patches that were not completely covered by the algae. Thus, it was tried to collect it without uptake of marine plants. The salinity of the water was measured with a refractometer in two different places: close to the shore, where it had a value of 4‰, and more further out, where the value measured was of 10‰. As for the temperature, the value displayed on the thermometer was of 1°C. After sieving, the sediment was washed with distilled water. It was kept overnight for a period of 24h to allow the sediment to settle, after which the overlaying water was removed and replaced with seawater (10‰ salinity). Each time new water was added atop of the sediment, the mixture was thoroughly homogenized. The homogenization was performed in order to
  • 17. 17"|"P a g e " % assure that the seawater penetrated the sediment evenly, since the sediment has a tendency to settle and accumulate at the bottom of the recipient in which it was kept. This procedure (change of overlaying water and homogenization of sediment) was done twice, the purpose being to raise the salinity level of the sediment up to 10‰. After 48h, the overlaying water was removed and the sediment was homogenized again, it was evenly distributed in re-sealable plastic bags, labeled, placed in the freezer at a temperature of -20°C to destroy any organisms that might be present in the sediment, and preserved until further use. The next step consisted of thawing the sediment, homogenizing it thoroughly, and determining the dry weight to wet weight ratio (dw:ww). The wet weight was determined by weighing the wet sediment on an aluminum boat. Three samples were weighed and the average of 6,0466g was used for the dw:ww ratio. The wet sediment from the three samples was then introduced into a muffle furnace and kept at 105°C for 24h. After 24h, the sediment was removed from the oven, cooled down, and re-weighed. The average of the dw (which had a value of 4,5769g), and the average of the ww, gave a ratio of 0,7569. The ratio was rounded up to 0.76 to ease further calculations. For complete calculations see Appendix A, table 9. 5.2 SEDIMENT SPIKING WITH ACETYL CEDRENE The first step in establishing the amount of AC needed for spiking was to determine the quantity of ww sediment needed for the experiment. The amount was chosen to cover 21 beakers of 600ml (143mm height, ∅82mm, DURAN) and a depth of 4cm (this height was chosen to fulfil the burrowing needs of the organisms studied). The glass beaker (600ml) was weighed at 118.270g, and then sediment was added until it reached the hight of 4cm. When weighed with sediment, the beaker gave a new mass of 292.074g. This accounted for 173.804g of ww sediment added per beaker, value that was rounded at 180g. After that it was decided that a 250ml beaker might be better for the experiment set-up, so the amount of ww sediment needed per beaker was scaled down by dividing the initial amount by 2. This gave a quantity of 90g of ww sediment needed per beaker.
  • 18. 18"|"P a g e " % At the time of the initial calculation for the amount of AC needed for sediment spiking, the experiment set-up consisted of 21 beakers with AC treatment. The calculations went as following: 90g ww * 21 beakers = 1890g ww sediment (total amount of ww sediment needed for spiking) An extra of 310g ww sediment was added (to ensure that the amount spiked was enough for the set-up). Thus, 2200g ww * 0.76 dw:ww ratio = 1672g dw sediment 50µg AC/g dw sediment * 1672g dw sedediment = 83600µg AC = 83.6 mg AC ~84 mg AC (amount of AC needed for spiking) The 84 mg of AC were used to create a stock sediment (2.4828g). Both the Control sediment (no added AC) and the sediment treated with AC were handled in the same way. In table 2 the actual amount of AC added to the stock sediment can be seen. Table 2. Values for spiked and Control sediment. In the Control, water was used to replace the AC. Aluminum boat (g) Sediment (g) H2O 10% (g) AC 50µg (g) Control 7.8118 2.3674 0.1216 - AC treatment 7.8136 2.4828 - 0.0871 The stock sediment was then added to 2.2kg of wet sediment. After that, the spiked sediment, as well as the Control sediment, was hand mixed in the fume hood and placed on a shaking table for 24h. The two types of sediment were additionally hand mixed several times throughout a two-day period. This was necessary in order to prevent the sediment from settling on the bottom of the buckets in which it was kept and to thoroughly homogenize it.
  • 19. 19"|"P a g e " % 5.3 TEST ORGANISMS: COLLECTION AND HANDLING All the organisms were collected from Roskilde Fjord (55°43'N, 11°58'E, Greshøj, Denmark) on the 27th of February, 2013. Macoma balthica was obtained by removing the sediment from the surface with a shovel and sieving it with a 2mm sieve, while Mya arenaria was harvested by digging deeper into the sediment. Macoma balthica was mainly collected from the areas that were more out sea (10‰ salinity), while the Myas were also collected in the areas situated close to the shore (salinity 4‰ and 10‰). The organisms were sampled randomly and a total of 38 Macomas and over 200 Myas were found. It was also intended to use Cerastoderma glaucum as a test organism.182 Cersatodermas were collected, mostly from the areas that measured a salinity level of 4‰. Unfortunately, they were all dead by the end of the experiment, thus they were not included in the experiment set- up section of this report. The next step consisted of acclimatizing the organisms from a temperature of 1°C, found in the natural environment, to 17°C, the temperature used for running the experiment. The organisms were brought into a climate room set to run at 4-6°C and sorted. They were then placed into plastic containers with sediment from the field, water (10‰ salinity), plastic cover, and were linked to an air supply. Each 3-4 days the temperature was raised by several degrees, from 4-6 to 10 to 17°C. The overlaying water was changed several times during the acclimatization period to offer a better living environment for the organisms. At the time of collection, all the participants in the process had a rough idea of the organisms that were being searched for. Thus, a few days into the acclimatization period, the organisms were identified by using Havets dyr og planter by Køie M. et. al. (2000) and The brackish- water fauna of northwestern Europe by Barnes R. S. K. (1994).
  • 20. 20"|"P a g e " % 5.4 EXPERIMENT SET-UP Before setting up the experiment, because most of the organisms died, due to inadequate handling, it was decided to reduce the actual experiment size down to 18 beakers: 9 for Control (3*Macoma, 3*Mya, and 3*without organisms) and 9 beakers with 50µg AC/g dw sediment (3*Macoma, 3*Mya, and 3*without organisms)(see figure 7). Figure 7. Experimental set-up. The treatment groups were divided in Control (no AC) and AC-treated group. In each of the beakers containing M. balthica and M. arenaria, 4 test organisms were added. Two additional groups with no organisms were added to the experimental set-up to assess microbial degradation. Each group had a total of 3 replicates. Sediment was added to each beaker (clean sediment to the Control beakers and treated sediment to the AC beakers) up to the level of 2 cm. Initially, the limit was 4 cm, but since the beakers were changed from 600mL to 250mL (117mm height, ∅61mm, DURAN), the sediment height was also diminished. Next, water (10‰ salinity, filtered with 10µm) was added up to the 200ml mark of each beaker. The beakers were covered with parafilm (to prevent evaporation of water), and air supply was ensured by air pumps connected through tubes to glass Pasteur pipettes (see figure 8). This set-up was kept for two days, after which the overlaying water was carefully removed (without disturbing the sediment) with a volumetric pipette and replaced with new water (10‰ salinity). Changing the overlaying water is an important step because decomposing organic chemicals enter the water phase and can pose a threat for the test organisms.
  • 21. 21"|"P a g e " % Figure 8. Experimental set-up. Parafilm was used to prevent evaporation of AC, as well as to offer support for the air pumps. The overall sizes of the organisms collected were in between 1.0 – 2.2cm for Mya arenaria and 0.8 – 1.7cm for Macoma balthica. Upon dissection it was determined that the Macomas with a size of 1.2cm were equal in biomass (~0.081g) with the Myas of size 1.4cm. Due to restrictions in organism numbers (only 38 Macomas were available), it was decided to add 4 organisms per beaker (corresponding to a density of 1,428 organisms/m2 ) and the sizes selected for each of them were: 0.8 – 0.9cm; 1.0 – 1.1cm; 1.1 – 1.2cm; 1.3 – 1.4cm for Macoma, and 1.0 – 1.1cm; 1.2 – 1.3cm; 1.5 – 1.6cm; and 1.7 – 1.9cm for Mya (one organism from each range specified)(see figure 7). These sizes were selected because they had matching biomass and were the most representative for the sampled populations. Next, the organisms were gently added to the beakers. The experiment was conducted for a 14-day period with the climate room set at the temperature of 17°C. During the preparation phase all the components of each beaker (Control and treatment) - sediment, water, and test organisms - were handled in precisely the same manner to avoid errors that can arise from reasons unrelated to the actual effects of the chemical. Additionally, 3 beakers (T0 1, T0 2, T0 3) with AC and no organisms were made for determining the initial conditions (i.e. the initial AC levels). They were kept for two days (under same conditions as the experiment set-up), and taken down, the sediment and water being separately stored in the freezer at -20°C.
  • 22. 22"|"P a g e " % 5.5. BURROWING BEHAVIOR The burrowing behavior of the organisms was monitored and noted down half an hour, 1 hour, and 8 hours after the exposure start. During the 2-week period in which the experiment was running, the set-up was checked upon once a day to make sure the oxygen supply was functioning properly. Any dead organisms found were removed and noted down. The burrowing behavior and mortality can be seen in Appendix B. The burrowing behavior was monitored in order to make sure that the test organisms accept the environment they were settled in and to see if they behave as expected. Under normal conditions, both species are normally burrowed completely in the sediment, having only their siphons extruding from it. % 5.6 WATER, TISSUE, AND SEDIMENT ANALYSIS After the 14-day period of exposure ended, the water, sediment, and organisms were prepared for further analysis. WATER. The first step consisted of removing the overlaying water with a 10ml pipette, determining the amount of water existent per beaker, and storing it in labeled blue-cap bottles (100ml, VWR). The volume of water existent per beaker ranged 130-140ml (see Appendix C, table 11 A and B). After, the water samples were placed in labeled plastic bags and frozen at - 20℃. TISSUE. Next, the organisms were taken out of the experimental beakers, rinsed with miliQ water, and left to clean their guts overnight (in new beakers with clean water, 10‰ salinity, and air supply). They were then dissected, the tissue being placed in labeled and re-sealable test tubes, and frozen at -80℃. SEDIMENT. The sediment was homogenized, placed in labeled and re-sealable plastic bags, and frozen at -20℃ until further analysis. PREPARATION OF SEDIMENT SAMPLES FOR GC-MS The sediment corresponding to Mya (sample 1, 2, and 3), Macoma (sample 1, 2, and 3), microbial degradation (sample 1, 2, and 3) with AC addition, and Mya (sample 1, 2, and 3), Macoma (sample 1, 2, and 3) without AC addition were thawed in warm water.
  • 23. 23"|"P a g e " % Aluminum trays were used to weigh 5g of wet sediment (from each individual sample), while a corresponding 5g of Diatomaceous Earth (Hydromatrix) were weighed separately (for exact measurements, see Appendix E, table 12). The sediment was mixed with the hydromatrix and homogenized using plastic spoons. The ASE extraction cells were prepared by adding two cellulose filters. 2.90 – 3.10g of silica gel were then added to the extraction cells, as a safety measure for avoiding water, and compressed with the insertion tool. A metal funnel was used to ease the process. Half of the mixture of sediment and hydromatrix belonging to every sample was then added to their corresponding ASE cell and compressed with the insertion tool. Next, 100!l of internal standard was added. The internal standard chosen was phenanthren-d10 (1500!g/ml toluene). For safety reasons, this step was performed under the fume hood. The remaining half of the sediment and hydromatrix mixture was added on top of the internal standard and compressed with the insertion tool, hydromatrix being used to fill the cell up to 1cm from the top. The cell was closed and placed on the Cell Tray of the ASE machine for sample extraction. Labeled glass vials were placed on the Vial Tray in the places corresponding to the extraction cells (see figure 9, left). In preparation of the ASE, the EPA-type VOA glass vials were kept in an oven at 550℃!to make sure there were no organic contaminants and the dichloromethane (CH2Cl2) was placed on an ice bath 2h prior to using the ASE machine. The program selected for the ASE machine was: a. Preheat (0 min) b. Heat (5 min) c. Static (15 min) d. Flush (50 vol) e. Purge (60 sec) f. Cycles (2) g. Pressure (2000 psi) h. Temperature (60℃) i. Solvent (Dichloromethane, 100%) More details on the function of the ASE200 machine are presented in Appendix D.
  • 24. 24"|"P a g e " % After all the cells were processed, the glass vials were taken to evaporate on the Evaporator SE 500 (see figure 9, right). Prior to that, 1 ml of toluene was added to each vial. Figure 9. (left) The ASE extraction cells being loaded on the Cell Tray. (right) Sample evaporation on the SE 500 machine. The program used on the SE 500 machine was: a. Entry 1: Direction = CW b. Entry 2: Time ON (Secs.) = (do not select any value) c. Entry 3: Time ON (Mins.) = (do not select any value) d. Entry 4: Time ON (Hrs.) = (do not select any value) e. Entry 5: Pulse/Min = 70 (which was later reduced to 50) f. Entry 6: Duty Cycle = 90% g. Entry 7: Setpt 1 = 15 deg. C (Top Manifold) h. Entry 8: Setpt 2 = 75 deg. C (Bottom block) The remaining samples were filtered by using a glass pipette, glass wool, and anhydrous sodium sulfate (Na2SO4) to prevent any water from ending up in the GC-MS machine, and then washed with toluene into a 5ml volumetric flask. The samples were then transferred to GC-MS vials, closed with a cap, and stored at -20℃.
  • 25. 25"|"P a g e " % The T0 samples, that were removed at the beginning of the experiment, were also prepared for the GC-MS analysis in the same way as the rest of the samples. Details on preparation for the ASE machine and on dw:ww measurements can be seen in Appendix A and E (table 10 and 12). Separately, the dw:ww ratio was determined. Aluminum trays were weighed, and 2g of sediment was added in order to determine the ww. Next, the sediment trays were added into an oven and kept overnight at 105℃. The sediment treated with AC, and the one without, were added to the oven at different times: 13:45, respectively 15:42, and were extracted from the oven at the same time, 14:00. The results can be seen in Appendix A, table 10. PREPARATION OF TISSUE SAMPLES FOR GC-MS The tissue sample tubes were taken out of the freezer, defrosted and placed on an ice bath. 2ml of MeOH and 2ml of water were added to each centrifuge glass containing tissue samples. The contents of the centrifuge glass were mixed with a Homogenizer and the tubes were placed back on the ice bath. The method used for packing of the ASE extraction cells with the tissue sample was mostly similar to the one used for packing the sediment samples. The difference consists of 4g of hydromatrix being mixed with the tissue. The entire homogenized mixture was then added to the extraction cell, followed by the internal standard that was added last. The preparation for the ASE200 machine was exactly the same (i.e. the glass vials kept in an oven at 550℃, the dichloromethane kept on ice, the program used by the machine). During the removal of the EPA-type VOA glass vials, the Macoma 3 sample treated with AC was broken due to human error. The program used for the evaporation on the SE 500 machine was the same as used during the sediment preparation. After the evaporation, the remaining samples were filtered by using a glass pipette, glass wool, and anhydrous sodium sulfate to prevent any water from ending up in the GC-MS machine, and then washed with toluene into a 5ml volumetric flask. The samples were then transferred to GC-MS vials, closed and stored at -20℃.
  • 26. 26"|"P a g e " % PREPARATION OF WATER SAMPLES FOR GC-MS The volume of each sample was measured and transferred to conical flasks. The values measured ranged between 66-77ml. All the samples had precipitate on the bottom and it was tried as much as possible to pour without disturbing it. In microbial degradation (1) all of the precipitate ended up in the conical flask. Note: In the lower section of the samples treated with AC, colloids could be observed. It was tried as much as possible to avoid taking them up while pouring the samples. The extractions were done in two rounds to ease handling: Round 1: Microbial degradation 1, 2, and 3 + Mac 1 and 2; Round 2: Mac 3 + Mya 1, 2, and 3. The compounds from the water were removed through Solid Phase Extraction (SPE), by using Strata-XL tubes from Phenomenex (500mg/6ml, 100u Polymeric Reversed Phase). The SPE consists of a number of 6 steps. 1. Condition. A vacuum manifold was used, and 3 ml of methanol (MeOH) were flushed over each column to wash and activate the filter. The vent was adjusted to secure the constant flow of 3ml/minute. 2. Equilibration. To rinse the tube from MeOH, an additional 3ml of water were used. Again, the vent was adjusted to secure the constant flow of 3ml/minute. 3. Load sample. The AC-water samples were loaded on the vacuum manifold. The vacuum pump was turned on and the vent on the vacuum manifold was adjusted at a flow of 3-10 ml/minute. 4. Wash. After all the samples went through the filter, each flask was flushed with 4 ml of water and added to the column. It is important to flush the conical flasks so that all of the potential compounds will go to the filter (this step was omitted for the Macoma 3 and Mya 1 samples due to human error). 5. Dry. The vacuum pump was kept on for 2 minutes, time in which the samples were dried out. After this step, the vacuum pump was turned off. 6. Elute Analyte. 3 ml MeOH were added to the tubes to elute the compounds collected by the filter. Collection flasks were placed under the SPE tubes.
  • 27. 27"|"P a g e " % Because the GC-MS machine’s column can be damaged in the presence of water, sodium sulphate was used to remove any trace of it from the samples. Glass wool was added to glass pipettes. Separately, a minute amount of Na2SO4 (on the tip of a small metal spoon) was placed in each sample glass. The Na2SO4 binds to H2O, impeding its access through the filter. The sample microbial degradation (3) was the only one that was handled slightly different, by adding Na2SO4 in the glass pipette, on top of the glass wool. The sample was then filtered through it. The microbial degradation (3) was the first sample to be processed and the procedure used on it did not seem to be efficient enough, thus the change in method was made. The small flasks with the eluted compounds in MeOH were each added 500µl of toluene and 100µl (at first only 50µl was added and halfway through the evaporation another 50µl was added) of the internal standard, phenanthren-d10 (1500µg/ml toluene) and placed on the Evaporator (SE500). Toluene is lipophilic and it will capture AC and keep it from evaporating. When the samples are evaporating, only the MeOH will evaporate while the toluene and lipophilic compounds will remain. Most of the samples were almost dry after evaporation due to inadequate monitoring (they were in the machine for half an hour and there was still MeOH left in the glasses; after another hour in the machine, they were almost completely dried out). To recover the samples, 1000µl of toluene was added to all of the vials, after which they were sonicated for two hours. Because of precipitate on the bottom, the samples were filtered one more time. Sodium sulphate was added to the samples and Pasteur pipettes with glass wool and sodium sulphate atop were used. The rinsed samples were collected in the GC-glasses and stored in the freezer until further use. 5.7 GC-MS ANALYSIS The GC-MS instrument used for the AC analysis consisted of a 6890N Network GC System, MS 5975, and a 7683B Series Injector, from Agilent Technologies (for a general description of the function of the GC-MS, see Appendix F). The method ran was called SIM (single ion monitoring) and the sub-method chosen was AC with Phenanthrene-d10. SIM is used if the purpose of the analysis is to quantify something (in our case AC).
  • 28. 28"|"P a g e " % For the analysis of AC, a blank containing dichloromethane was placed on the autosampler to commence the sequence. The purpose of this first blank (Blank1) was to rinse the needle of the injector before proceeding to the samples treated with AC. Next followed the water, tissue, and sediment samples. Seven more blanks were added in between the samples at a 5-7- step interval, the final blank (Blank8) following the last sample. At the end of the sequence, 4 GC-MS-vials with different concentrations of AC (30, 100, 150, 250 !g) were mounted on the autosampler and used to calibrate the machine. The T0 sediment samples were ran separately on the GC-MS, the loading sequence being T0(1), T0(2), T0(3), AC 30, AC 100, AC 150, AC 250. They were treated in the same way as all the other samples. As the GC-MS is started, the needle of the injector is firstly washed with CH2Cl2. Only after this step has been performed, the first sample is taken for analysis (in our case Blank1). It takes 28.95 minutes for the machine to process one sample, and some cooling time in between samples is also required. The parameters used for running the GC-MS instrument were: Inlet-F Temperature – 250℃ (the temperature required for changing phase from liquid to gas); Column Flow – 1.0 ml/min (represents the speed of carrying the analyzed compound with helium. Helium is chosen in our case because it doesn’t interact with AC); Inlet-F Pressure – 8.1 Pa; Oven Temperature - 80℃; Inlet-F Total Flow – 23.8 ml/min (this parameter illustrates the flow of gas used to rinse the machine); MS Quad – 150℃!(the temperature in the quardupole); MS Source – 250℃; HiVac – 6.20e-006 (the vacuum inside the MS); These numbers represent the parameters existent at the beginning of the analysis (t = 0 minutes). It should be noted that some parameters change over time (e.g. the oven temperature). The program used for the oven can be seen in table 3.
  • 29. 29"|"P a g e " % Table 3. Program used for the temperature increase in the oven Step ℃/min Next ℃ Hold min Initial 80 2.00 Round 1 20.00 165 11.00 Round 2 50.00 200 2.00 Round 3 20.00 280 5.00 As the first sample is harvested by the injector, 1!l of the mixture of AC and phenanthrene- d10 is injected into the GC unit. The mixture is carried further by helium and is vaporized as the temperature reaches 250℃. Helium was chosen because it does not react with AC. In the oven, the chemicals are guided by the helium along the column (length 30m, ∅0.25, DB-1701, Agilent Technologies), and the temperature is slowly increased from 80 to 280℃. Inside the column the compounds are sorted by boiling point and polarity, so that the compound with the lowest boiling point is lead through first and the heavier compounds last. After passing through the column, the chemicals enter the MS unit. In the MS there is a vacuum and therefore no other molecules, except the ones lead there by the column. Here the compounds are bombarded with electrons, thus making them lose electrons and create positive ions. Most positive ions of organic compounds are charged with a surplus of energy and in the absence of other ions the molecule will split into ion fragments. These ion fragments represent the specific fingerprint of the molecular ion. Each ion has a specific mass to charge ratio (m/z) and is lead through a small hole in a negatively charged plate and into the quadrupole. The charge between the poles in the quadrupole changes with a frequency of 1 MHz (1.000.000 times/sec). At a set current and frequency, only ions with a specific mass to charge ratio will pass through. The current, produced by the ions, is amplified by an electron multiplier HED/EM (High Energy Dynode/Electron Multiplier). In the HED, the flow of ions from the quadrupole hits a dynode that releases electrons. Each of these electrons hits the inner walls of the EM and releases more electrons. This electron flow is shown as a peak on the GC graph, where the area under the curve is an expression of the amount of ions. When running the SIM programme, the current and frequency is changed over time so that the ions will be “sorted” by their mass to charge ratio. This change can occur between 1 and 10 times/sec. If the change in current and frequency is set too fast, the sensitivity will be lowered. A strong current increases the sensitivity, but shortens the lifespan of the machine. Three types of reference ions were selected for both AC and the internal standard:
  • 30. 30"|"P a g e " % Group 1 – the AC ions – Consisted of the target ion 246.00 m/z (Tgt), and two qualifying ions: 161.00 m/z, 231.00 m/z (mass/charge)(Q1 and Q2). Group 2 – Deuterium phenantherene-d10 ions – Consisted of the target ion 188.00 m/z (Tgt), and the qualifying ions: 80.00 m/z and 189.00 m/z (Q1 and Q2). 5.8 STATISTICAL METHODS In order to test the hypothesis of this report, the General Linear Model Test and One-Way ANOVA were used. The Tukey Test was also used to assess the differences between individual samples. The program used for computing all the statistical data was SYSTATS. The analysis of variance (ANOVA) is used to investigate the differences between the means of two or more samples. A prerequisite of ANOVA is that the samples that undergo analysis must be evenly distributed. The reason for choosing One-Way ANOVA is because we were dealing with only one parameter (AC concentration). The General Linear Model Test was used merely because it offered more options than ANOVA, while still including the analysis of variance. While performing the tests, the confidence interval chosen was always 0.95. As additional options, the normality test, Kolmogorov-Smirnov, and the Equality of variance test, Levene, were chosen.
  • 31. 31"|"P a g e " % 6. RESULTS During the exposure of the organisms to AC and after the analysis of the water, tissue, and sediment samples on the GC-MS machine, two different sets of effects have been monitored. They can be grouped into effects of AC on the test organisms (these have been observed through behavioral changes and assessment of mortality levels) and fate of AC (change in AC concentration in water, sediment, and soft tissue). 6.1 EFFECTS ON ORGANISMS MORTALITY Table 4 offers an overview of the number of organisms that were alive at the end on the experiment exposure and their biomass. Table 4. Tissue weight and corresponding number of organisms for: A. Mya arenaria, and B. Macoma balthica AC TREATMENT AC TREATMENT Weight (g) Nr. of org. Weight (g) Nr. of org. Mya 1 0.1865 1 Mac 1 0.2683 1 Mya 2 0.2800 2 Mac 2 0.3088 2 Mya 3 0.4481 3 Mac 3 0.4182 4 CONTROL CONTROL Mya 1 0.0998 2 Mac 1 0.0628 4 Mya 2 0.1368 2 Mac 2 0.1395 3 Mya 3 0.0753 2 Mac 3 0.2039 2 During the 14-day exposure period, a total number of 5 organisms died from the Mya AC groups, while 4 organisms died from the Macoma AC group From the mortality graphs (figure 10 and 11), we can see that under similar conditions, Macoma balthica has a higher resistance to environmental stress than Mya arenaria, since less organisms from the Macoma group died, compared to the Mya group.
  • 32. 32"|"P a g e " % Figure 10. Cumulative comparison of mortality of Mya between Control and samples treated with AC. From comparing the two graphs we can see that the Myas began dying already from the second day of exposure, whereas the Macomas - on the 5th day. Figure 11. Cumulative comparison of mortality of Macoma between Control and samples treated with AC. BURROWING BEHAVIOR During the exposure period, the burrowing behavior of the test organisms was observed. This was done in order to see how the organisms perceive the sediment they were introduced to, if they accepted the conditions (i.e. AC treatment, no treatment), and if they behave as predicted. Under normal circumstances, the organisms would instantly start burrowing once placed atop of the sediment. In the presence of AC, this behavior might be altered as the organisms might consider the new environment ‘unfit’ for burrowing.
  • 33. 33"|"P a g e " % To obtain a better overview of the burrowing behavior exhibited by Macoma balthica and Mya arenaria during the 14-day exposure interval, the burrowing-table from Appendix B was used to see how often (in %) the organisms would be inside, outside, or halfway in the sediment. 1) Macoma AC and Macoma Control After summing up all the instances in which the organisms would be in, out, or halfway in the sediment, it was found that in the groups treated with AC, Macoma would be burrowed in ~64,5% of all the possible cases, halfway burrowed in ~18,5% of the cases, and atop of the sediment in 17% of the cases. As for the Control group, Macoma was burrowed in ~70% of the cases, halfway in ~10,5%, and out in ~19,5% of the cases. Macoma’s burrowing behavior shows that in most of the cases they burrow well and stay in the sediment. This applies for both Control and AC treated samples. There were however some Macoma that did not burrow fully or stayed above the sediment. That might be due to individual preferences. In general, the behavior from both types of treatments follows a similar pattern. Figures 12 and 13 offer a better view of the behavior exhibited by the organisms form the Control and AC groups, during the 14-day exposure period. %%%%%%%%%%%%%%%%%% % Figure 12. Burrowing behavior exhibited by Macoma in the Control groups. From figure 12 we can see that 8 out of 12 organisms burrowed in the sediment as soon as the exposure began. This is a good sign of organism fitness and shows that the organisms were not affected (stressed) too much during the acclimatization and exposure period. 0% 2% 4% 6% 8% 10% 12% 1/2h% 1h% 8h% d1% d2% d3% d4% d5% d6% d7% d8% d9% d10% d11% d12% d13% d14% in% h% out% Macoma%Control%Burrowing%Behavior% No.of%organisms% Time%
  • 34. 34"|"P a g e " % From figure 13 we can see that it took a one full day for the Macomas from the samples treated with AC to burrow in the sediment, compared to the ones from the Control samples that burrowed fully within the first 1/2h. Also, the number of organisms that chose to not fully burrow or not burrow at al was slightly higher in the AC treated group compared to the Control group. %%%%%%%%%%%%%%%%%% Figure 13. Burrowing behavior exhibited by Macoma in the groups treated with AC. 2) Mya AC and Mya Control The burrowing of Mya was not as successful as that of Macoma. It was expected that they would go in the sediment but they mainly stayed partially burrowed and close to the surface of the sediment. In the AC treatment, the organisms were burrowed in 25,5% of the cases, halfway in the sediment in ~52% of the cases, and out ~22,5% of the time. In the Control group, ~22% of the time the Myas were burrowed, they were halfway in the sediment ~18% of the cases, and the remaining ~60% of the time they were atop of the sediment. Figures 14 and 15 illustrate the burrowing behavior of Mya in the Control samples and in the samples treated with AC. From these graphs we can see that Mya has a chaotic distribution of organisms, both in the Control and AC group. 0% 2% 4% 6% 8% 10% 12% 1/2h% 1h% 8h% d1% d2% d3% d4% d5% d6% d7% d8% d9% d10% d11% d12% d13% d14% in% h% out% Macoma%AC%Burrowing%Behavior% Time% No.of%organisms%
  • 35. 35"|"P a g e " % Figure 14. Burrowing behavior exhibited by Mya in the Control groups. In both the Control and AC group there is a tendency for the organisms to burrow in the sediment, after which the tendency slowly turns towards going out of the sediment. In the Control it can be seen that in day 4 there are just 4 organisms out of the sediment, one day later the number increasing to 10, after which, on the 9th day the number goes down to 3. This could be explained by the fact that the organisms that went out of the sediment, after being previously burrowed, simply died and were removed. Figure 15. Burrowing behavior exhibited by Mya in the groups treated with AC. 0% 2% 4% 6% 8% 10% 12% 1/2h% 1h% 8h% d1% d2% d3% d4% d5% d6% d7% d8% d9% d10% d11% d12% d13% d14% in% h% out% Mya%Control%Burrowing%Behavior%% Time% No.of%organisms% 0% 2% 4% 6% 8% 10% 12% 1/2h% 1h% 8h% d1% d2% d3% d4% d5% d6% d7% d8% d9% d10% d11% d12% d13% d14% in% h% out% Mya%AC%Burrowing%Behavior% Time% No.of%organisms%
  • 36. 36"|"P a g e " % 3) Comparison between species The burrowing behavior of the two organisms gives us a clear insight on the different responses that the two species have when dealing with the same stress factors. When comparing the two organisms, we can observe that Macoma burrowed more readily into the sediment compared to Mya and this may indicate that Macoma is more resistant to external stress (the burrowing graphs from Macoma are stable and the mortality is lower compared to Mya, that have fluctuating burrowing behavior and higher mortality). 6.2 FATE OF AC The results obtained from the GC-MS machine, which are relevant to our study, can be seen in table 5. These numbers were used to determine whether the AC added to the different samples was biodegraded during the 14-day period in which the experiment was held. Table 5. Amount of AC measured in sediment, water, and tissue on day 14, and initial amount (T0) Treatment( Sediment(AC( Body( burden( Water( ,, (ug/g), (ug/g), (ug/ml)% Mya,ac,1, 23.1147, J% J% Mya,ac,2, 23.1214, J% J% Mya,ac,3, 25.0069, J%% J% Mac,ac,1, 24.3754, 92.1729, J% Mac,ac,2, 22.0136, 76.2953, J% Mac,ac,3, 22.5651, DAMAGED, J% T0,initial,ac,1, 37.1318, >, J% T0,initial,ac,2, 35.6810, >, J% T0,initial,ac,3, 40.8549, >, J% Microbial,degradation,1, 28.1599, J, J% Microbial,degradation,2, 22.1222, J, J% Microbial,degradation,3, 21.2805, J, J% No,organisms,1,(control), >, J, J% No,organisms,2,(control), >, J, J% No,organisms,3,(control), >, J, J%
  • 37. 37"|"P a g e " % ACETYL CEDRENE IN SEDIMENT As expected, all the sediment samples spiked with AC showed the presence of AC on the GC- MS mass-spectrum. The presence of AC is showed in the form of a peak in the region where the selected target ion, and the qualifying ions are found (see figure 16 and 17). Figure 16. The small peak to the left represents the abundance of AC found in the sample. The peak to the right represents the mass-ion spectrum for the internal standard, phenanthrene-d10. Figure 17. The ions used for identifying AC were the target ion 246.00 m/z (Tgt), and the qualifying ions 161.00 m/z, 231.00 m/z (Q1 and Q2).
  • 38. 38"|"P a g e " % Both One-Way ANOVA and the General Linear Model were used to test if our alternative hypothesis (HA – AC conc. T0!≠ AC conc. Tend) is accepted or rejected. In other words, to see if there is a notable difference between the amount of AC found in the T0 samples, and the amount found in the Mya, Macoma, and microbial degradation samples, at the end of the exposure period. A bar chart graph was selected to better illustrate the differences in AC amount (!g/g) found in the T0 samples, and the ones found in the no-AC/no-organism sample (Control), and the Mya, Macoma, and microbial degradation samples treated with AC (see figure 18). Figure 18. (left) Comparison between AC concentrations in T0 and Tend samples. (right) Comparison between AC concentrations within the the Tend samples. From the bar chart we can see, as expected, that the AC concentration in the T0 samples is greater than that of the Mya, Macoma, and microbial degradation samples. It should be noted that the amount of AC present in the T0 samples is slightly lower (avg. 38!g/g dw sediment) than the nominal concentration of AC in the sediment (50!g/g dw sediment). As for the Control samples, no trace of AC has been detected. According to Levene’s Homogeneity Test (table 6), the data obtained is evenly distributed, with a p-value of p = 0.078. Table 6. Homogeneity of variances Levene's Test for Homogeneity of Variances Test Statistic p-Value Based on Mean 3.314 0.078 Based on Median 0.459 0.719
  • 39. 39"|"P a g e " % We proceeded by presuming that the alternative hypothesis is accepted. By running the General Linear Model test on the T0, Macoma AC, and Mya AC groups, a p-value of p = 0.000 was obtained (see table 7). This means that there is a significant difference between the AC level in the T0 samples and the one from the other samples (p<0.05). Table 7. ANOVA results Analysis of Variance Source Type III SSdfMean SquaresF-Ratiop-Value TREATMENT$465.346 3 155.115 25.939 0.000 Error 47.840 8 5.980 To further test which of the samples are different (or if all the samples are different) from the T0 sample, the Tukey HDS test was performed. From the results presented in table 8, we can observe that the AC concentration in T0 is significantly different from that of the Macoma AC (p = 0.000), Mya AC (p = 0.000), and microbial degradation AC (p = 0.001) samples. On the other hand, when compared among each other, the end samples (Tend) did not show a significant difference among AC levels: Macoma AC vs Mya AC – p = 0.980, Macoma AC vs microbial degradation AC – p = 0.971, and Mya AC vs microbial degradation AC – p = 1.000. Table 8. Results obtained from the Tukey Test. Tukey's Honestly-Significant-Difference Test TREATMENT$(i)TREATMENT$(j)Differencep-Value95% Confidence Interval Lower Upper Mac ac Mya ac -0.763 0.980 -7.157 5.631 Mac ac Micro degr ac -0.869 0.971 -7.264 5.525 Mac ac T0 initial ac -14.905 0.000 -21.299 -8.510 Mya ac Micro degr ac -0.107 1.000 -6.501 6.288 Mya ac T0 initial ac -14.142 0.000 -20.536 -7.747 Micro degr ac T0 initial ac -14.035 0.001 -20.429 -7.641 ACETYL CEDRENE IN TISSUE Traces of AC have been found in the Macoma samples treated with AC, with a value of 92!g/g for replicate 1, and 76!g/g for replicate 2. These results were displayed in the form of a small peak on the mass-spectrum graph. Even though the peaks themself were under the 3xbackground noise value needed for qualifying the samples, we proceeded in determining the AC concentration. We decided to do this as none of the other samples showed a similar
  • 40. 40"|"P a g e " % trend (thus we can exclude the possibility of contamination from other samples). No traced of AC were detected in any of the Mya samples. Figure 19. AC peak on the mass-spectrum in the Macoma AC 2 sample. ACETYL CEDRENE IN WATER No detectable traces of AC have been found in the water phase of the samples. 7. DISCUSSION 7.1 EFFECTS OF ACETYL CEDRENE During the experimental period, both burrowing behavior and mortality have been monitored. From the mortality graphs presented in section 6.1 (figure 10 and 11), we could observe that several organisms from both the Mya and Macoma samples have died. This was a trend that was not expected, as the concentration chosen for AC was not high enough to be considered lethal. We believe that the mortality might not be due to the presence of AC, as both the Control and AC treated samples of each of the test organisms have a similar number of dead organisms (i.e. 5 organisms in Control and 5 in AC treated samples for Mya; 3 in Control and 4 in AC treated samples for Macoma).
  • 41. 41"|"P a g e " % From the graphs we can also see that M. arenaria began dying earlier in the exposure period (day 2) compared to M. balthica (day 5). Also, by the end of the experiment, a larger number of Myas (10 in total) was reported dead, compared to Macoma (7 in total). We presume that the reason why some of the organisms died was because of handling and constant stress brought to their environment (e.g. acclimatization, frequent movement of the organisms, defective air pumps). Another explanation for the increasing numbers of dead organisms per beaker might be that once one of the organisms died, decomposing organic matter was released, hence contaminating the water and making the other organisms more susceptible to dying. If multiple toxic compounds are present in the environment, the toxicity of the mixture will approximately sum up the values of toxicity of the individual components (Walker et. al., 2006). This means that every individual chemical would roughly have the same toxicity when measured in a mixture or measured alone. The concentration of each of the chemicals that take part in a mixture dictates the levels of toxicity that each of the chemicals will have. This information might be relevant to our study because we do not know if the sediment used for the experiment set-up was contaminated with any other compounds. Thus, if any other toxic compound was present in the sediment, it could explain why organisms from both the Control and AC treatment groups died. When observing the burrowing behavior, two different trends were noticed, a stable burrowing behavior for Macoma and a fluctuating one for Mya. M. balthica behaved as expected, burrowing in the sediment by the end of the first day, both in the Control and treatment group (see section 6.1, figure 12 and 13). This is generally a sign of good fitness. If comparing the Control group to the AC treated one, it can be seen that most of the organisms in the Control were fully burrow within half an hour, whereas it took an entire day for the organisms in the treatment group to do the same. This might be because they sensed the presence of AC and it took time for them to adjust to the new environment. Also, the number of organisms that did not fully burrow (halfway in) or not burrow at all (out) was slightly higher in the AC treated group compared to the Control group. This might also be due to the presence of AC in the former. M. arenaria’s burrowing behavior shows a totally different distribution pattern, as the data is more chaotically dispersed. This fluctuation in burrowing behavior numbers seen in the first
  • 42. 42"|"P a g e " % half of the graphs (for both the Control and AC samples) might be explained by the fact that the monitoring was performed by different people in different days. No specific method of assessing the burrowing behavior was established. Thus, what one person might have noted down as halfway in the sediment, another might have perceived as out of the sediment (the same applies for burrowed vs halfway burrowed). The way in which a person saw in what state the organisms were was especially affected by the angle from which the observer looked at them (see figure 20). However, it might be argued that if this was the case, why didn’t the same pattern appear in the Macoma samples as well. In the case of Macoma, it was easy to say, without any problem, if the organism was inside, halfway, or outside of the sediment. However, Mya was more problematic as one could not be always sure of the actual position in which they were (the delimitations between in/halfway and halfway/out, were hard to establish). When looking at the second half of the two graphs, the fluctuation in patterns was also a result of mortality. Figure 20. The burrowing behavior results might be slightly biased by the angle at which the observation was made (i.e. viewing the organisms from atop of the beaker or from side- view through the glass). Research states that M. arenaria has greater difficulty in reburrowing after disturbances. This is due to the size its foot, which remains the same as the clam grows, therefore the older the clam, the less successful it is at re-burrowing (Checa & Cadee, 1997; Pfitzenmeyer & Drobeck, 1967). In our experiment this could imply that the larger organisms were not able to burrow. If the clam was placed horizontally, it might have difficulties to turn itself vertically and commence burrowing.
  • 43. 43"|"P a g e " % 7.2 FATE OF ACETYL CEDRENE When assessing the concentration level of AC in the T0 sample, it was observed that the initial concentration was lower than expected (~38!g/g dw sediment, instead of the aimed value of 50!g/g dw sediment). This might be due to loss during handling, evaporation from the system, and degradation mediated by microbes. From the results obtained from the one-way ANOVA, we can see that there is a significant difference between the AC concentration of the T0 sample and that of the microbial degradation sample (p = 0.000). We believe that this is mainly a result of microbial activity. When comparing the AC level of the microbial degradation samples to that of the Macoma AC and Mya AC samples, the statistical data showed that there was no significant difference (microbial degradation vs Macoma, p = 0.971; microbial degradation vs Mya, p = 1.000). This implies that the two test organisms were not efficient at taking up and metabolizing AC. Furthermore these results show that the movement of the organisms in the sediment had no effect on microbial degradation. We were expecting to see a lower level of AC in the samples containing M. balthica, due to its feeding strategy and because the water was filtered, forcing Macoma to obtain its nutrients solely from the sediment. Traces of AC have been found in the tissue of the organism, suggesting that Macoma did take up the contaminant from the sediment. The actual concentration of the xenobiotic in the tissue was higher than the initial AC concentration added to the system. Since this did not significantly affect the overall concentration present in the sediment, we could presume that the organism was accumulating and storing it, but the rate at which they did so was too slow to have an impact. This could be supported by research on M. balthica with respect to other organic contaminants. For example, it has been shown that Macoma is efficient in accumulating PAHs, but not biortansforming them (Rust et. al., 2004). As for Mya arenaria, it was expected that it would be less efficient at taking up AC from the sediment, due to its suspension-feeding habits. In general, Mya has been shown to be capable of metabolizing some PAHs (e.g. benzo[∝]pyrene) at a higher rate than M. balthica, however this doesn’t seem to be the case with AC.
  • 44. 44"|"P a g e " % 8. CONCLUSION From the result obtained from ANOVA, we could conclude that the alternative hypothesis is accepted because there is a significant difference between the T0 samples and the Macoma AC and Mya AC samples (T0 vs Macoma AC, T0 vs Mya AC, p = 0.000). However, because the microbial degradation was not significantly different when compared to the samples with organisms, we can safely state that any difference in AC concentration detected in the Macoma and Mya samples was due to the presence of microbial degradation. Thus, we have to reject our alternative hypothesis and accept the null hypothesis; the presence of Macoma balthica and Mya arenaria does not affect the fate of AC, but microbial degradation does. Since there is no significant difference between the amount of AC found in the Macoma and Mya samples, we can not state which of them has the greatest impact on AC, or if there is any impact at all. When looking at the effect of sediment-associated AC on the test organisms, the mortality graphs provide no evidence that mortality was caused by AC. As for the burrowing behavior, we believe that the organisms were aware of its presence, and therefore they were not particularly keen to burrow (at least in the case of Mya). It should be also mentioned that the AC ingested by Macoma might have had an effect on the actual organisms, but we were not able to tell how exactly they were affected.
  • 45. 45"|"P a g e " % 9. APPENDICES 9.1 APPENDIX A – dw:ww measurements Table 9. dw:ww measurements for determining the amount of sediment needed for experimental set-up. Aluminum boat - WW (g) WW sediment (g) Aluminum boat – DW (g) DW sediment (g) 7,3448 5,6864 5,9651 4,3067 10,3840 8,7218 8,2511 6,5889 5,3954 3,7315 4,4989 2,8351 Table 10. Measurements for dw:ww AC TREATMENT Aluminum tray (g) Sediment – wet weight (g) Sediment + tray – dry weight (g) Sediment – dry weight (g) Mac 1 1.6653 2.1590 3.2652 1.5999 Mac 2 1.6067 2.1118 3.2152 1.6085 Mac 3 1.6168 2.1509 3.2340 1.6172 Mya 1 1.6051 2.1212 3.1968 1.5917 Mya 2 1.6186 2.1324 3.2447 1.6261 Mya 3 1.6103 2.1303 3.2436 1.6333 Micro. degr. 1 1.6087 2.1030 3.1896 1.5809 Micro. degr. 2 1.6075 2.1440 3.2586 1.6511 Micro. degr. 3 1.6140 2.1305 3.2463 1.6323 NO AC TREATMENT Mac 1 1.6300 2.0730 3.2231 1.5931 Mac 2 1.6180 2.0840 3.1949 1.5769 Mac 3 1.6156 2.0580 3.1948 1.5792 Mya 1 1.6062 2.1601 3.2653 1.6591 Mya 2 1.6040 2.1560 3.2580 1.6540 Mya 3 1.5990 2.1445 3.2167 1.6177 No organisms 1 1.6054 2.0517 3.1749 1.5695 T0 SAMPLES (AC TREATMENT) T0 1 1.6060 3.7511 4,4629 2.8569 T0 2 1.6129 2.8668 3,8033 2.1904 T0 3 1.6010 3.2387 4,1359 2.5349
  • 46. 46"|"P a g e " % 9.2 APPENDIX B – Burrowing behavior exhibited over a 14-day period %% Mya"AC% Mya"Control% Time/beaker%no.% 1% 2% 3% 1% 2% 3% after"1/2h" 1i,%2h,%1o% 2i,%2o% 1i,%2h,%1o% 1i,%3h% 1i,%1h,%2o% 1i,%3o% after"1h" 2i,%2h% 1i,%3o% 2i,%2o% 2i,%1h,%1o% 2i,%1h,%1o% 1i,%3o% after"8h" 2i,%2h% 2i,%2o% 2i,%1h,%1o% 2i,%1h,%1o% 2i,%2o% 2i,%1h,%1o% 26.03.%Tue% 2i,%2h% 2h,%2o% 2i,%1h,%1o% 2i,%1h,%1o% 2i,%2o% 2i,%1h,%1o% 27.03.%Wed% 4h% 2h,%2o% 2i,%1h,%1o% 2i,%1h,%1d% 1i,%1h,%2o% 2i,%2o% 28.03.%Thu% 4h% 3h,%1o% 2i,%1h,%1o% 1i,%2h,%1d% 1i,%1h,%2o% 1i,%2h,%1o% 29.03.%Fri% 2i,%2h% 4h% 2i,%1h,%1o% 1i,%2h,%1d% 1i,%1h,%2o% 1i,%1h,%2o% 30.03.%Sat% 4h% 4h% 2i,%1h,%1d% 3o,%1d% 1i,%3o% 4o% 31.03.%Sun% 4h% 4h% 2i,%1h,%1d% 3o,%1d% 1i,%3o% 4o% 01.04.%Mon% 1h,%3d% 4h% 2i,%1o,%1d% %%%%%3o,%1d"% 2i,%2o% 4o% 02.04.%Tue% 1h,%3d% 4h% 2i,%1o,%1d% 3o,%1d% 1i,%2o,%1d% 3o,%1d% 03.04.%Wed% 1h,%3d% 4h% 2i,%1o,%1d% 3o,%1d% 1i,%2o,%1d% 3o,%1d% 04.04.%Thu% 1h,%3d% 4h% 2i,%1o,%1d% 1h,%2o,%1d% 1i,%2o,%1d% 3o,%1d% 05.04.%Fri% 1h,%3d% 3h,%1d% 2i,%1o,%1d% 1h,%2o,%1d% 1i,%2o,%1d% 3o,%1d% 06.04.%Sat% 1o,"3d% 2h,%1o,%1d% 2i,%1o,%1d% 1h,%2o,%1d% 1h,%1o,%2d% 3o,"1d"% 07.04.%Sun% 1o,%3d% 2h,%1o,"1d% 1h,%2o,%1d% 1h%2o,%1d% 1h,%1o,%2d% 3o,%1d% 08.04.%Mon% 1o,%3d% 1h,%2o,%1d% 1h,%2o,%1d% 1h,%2o,%1d% 1h,%1o,%2d% 1h,%2o,%1d% Dissection% % 1d" " 1d" " 1d" LEFT% 1" 2"" 3" 2" 2" 2" ! Mac"AC" Mac"Control" Time/beaker%no.% 1" 2" 3" 1" 2" 3" after"1/2h! 2i,%2h" 2i,%2o" 1i,%3h" 3i,%1h" 3i,%1o" 2i,%2o" after"1h! 2i,%2h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1o" 2i,%2o" after"8h! 2i,%2h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1o" 2i,%2o" 26.03.%Tue% 3i,%1h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1o" 2i,%2o" 27.03%Wed% 3i,%1h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1o" 2i,%2o" 28.03%Thu% 3i,%1h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1o" 2i,%2o" 29.03%Fri% 3i,%1h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1h" 2i,%2o" 30.03%Sat% 3i,%1h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1d" 2i,%2o" 31.03%Sun% 3i,%1h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1d" 2i,%2o" 01.04%Mon% 3i,%1h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1d" 2i,%2o" 02.04%Tue% 3i,%1h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1d" 2i,%2o" 03.04%Wed% 3i,%1h" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1d" 2i,%2o" 04.04%Thu% 3i,%1d" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1d" 2i,%2o" 05.04%Fri% 3i,%1d" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1d" 2i,%1o,%1d" 06.04%Sat% 3i,%1d" 2i,%2o" 3i,%1h" 3i,%1h" 3i,%1d" 2i,%1o,%1d" 07.04%Sun% 2i,%2d" 1i,%2o,%1d" 3i,%1h" 3i,%1h" 3i,%1d" 2i,%1o,%1d" 08.04%Mon% 1i,%1h,%2d" 1h,%1o,%2d" 3i,%1h" 3i,%1h" 2h,%1o,%1d" 1h,%1o,%2d" Dissection% 1d" " " " " " LEFT% 1" 2" 4" 4" 3" 2" Legend:" i%=%inside,%h%=%halfway,%o%=%out%(of%sediment),%d%=%dead%
  • 47. 47"|"P a g e " % 9.3 APPENDIX C – Water volume in samples (from overlaying water) Table 11. A. Overlaying water volume from the AC treatment AC Treatment Time Organisms (beaker nr.) Overlaying water (ml) 15:02 Mya (1) 130 Mya (2) 130 Mya (3) 130 15:18 Macoma (1) 130 Macoma (2) 130 Macoma (3) 130 15:53 Microbial degradation (1) 140 Microbial degradation (2) 130 Microbial degradation (3) 130 Table 11. B. Overlaying water volume from the Control samples CONTROL Time Organisms (beaker nr.) Overlaying water (ml) 14:32 – 14:54 Mya (1) 130 Mya (2) 140 Mya (3) 130 14:08 – 14.29 Macoma (1) 130 Macoma (2)* 140 Macoma (3) 130 14:00 No organisms (1) 140 No organisms (2) 100 No organisms (3) 140 *in the Macoma (2) beaker, there were fine particles of sediment suspended in the water column.
  • 48. 48"|"P a g e " % 9.4 APPENDIX D - Laboratory Techniques: The ASE Machine: Accelerated Solvent Extractor Accelerated Solvent Extraction (ASE) is a method used for the extraction of test compounds from soil or other solid matrices. The process itself is fully automated. The machine is made up of a static part (consisting of the Electronics Area, Oven Area, and the Solvent Reservoir Compartment) and a mobile part (consisting of the Needle Mechanism, the Cell Tray – where the cells are loaded –, and the Vial Tray – where the glass-vials are positioned –). The Cell Tray can support a number of 24 cells and 4 rinse-tubes, while the Vial Tray can support 26 vials (60ml, clear glass) and 4 rinse-vials (60ml, amber glass)(vial type: EPA-type VOA) (DIONEX, 1999). Figure 21. ASE machine components (image source: DIONEX, 1999) Prior to using the ASE machine, the Dichloromethane is placed on an ice bath to avoid the formation of bubbles (Dichloromethane has a low boiling point) and the Nitrogen pump is turned on. As mention earlier in the report, the program selected for the ASE machine was: a. Preheat (0 min) b. Heat (5 min) c. Static (15 min)
  • 49. 49"|"P a g e " % d. Flush (50 vol) e. Purge (60 sec) f. Cycles (2) g. Pressure (2000 psi) h. Temperature (60℃) i. Solvent (Dichloromethane, 100%) Before running any of the loaded cells, the machine will first rinse itself with Dichloromethane and deposit the waste into the amber rinse-vials. After this step, the samples are processed. The standard procedure for running a sample-cell consists of preparing the cells and loading them on the Cell Tray (the same is done with the glass-vials). Once the machine is started, the cells and glass vials are rotated to the initial positions specified by the running method. The machine’s needle then perforates the glass-vial corresponding to the processed cell. The cell is picked-up and moved to the oven. Dichloromethane is then used to wash the cell. The next step consists of heating the cell up to 60℃ (so the cell reaches thermal equilibrium) and pressurizing it to 2000 psi. Static extraction then takes place, after which the contents of the cell are re-washed with fresh solvent. As Dichloromethane passes through the sample, it attaches to and collects the chemicals of interest, washing them into the glass vials situated on the Vial Tray. The process ends with the unloading of the cell.
  • 50. 50"|"P a g e " % 9.5 APPENDIX E - Sample preparation for ASE Table 12. ASE guideline. This table records the amount of sediment and hydromatrix used for each sample per ASE cell. The far right column illustrates the number of sample corresponding to each position on the ASE machine. AC TREATMENT Sediment (g) Hydromatrix (g) Corresponding cell (nr.)/(ASE nr.) Mac 1 5.79 5.05 1%(2) Mac 2 5.34 5.02 2%(3) Mac 3 5.11 5.12 3%(4) Mya 1 5.04 5.10 4%(5) Mya 2 5.74 4.99 5%(6) Mya 3 5.73 5.00 6%(7) Micro. degr. 1 5.72 5.00 7%(8) Micro. degr. 2 5.51 4.97 8%(9) Micro. degr. 3 5.67 5.03 9%(10) NO AC TREATMENT Mac 1 5.23 5.02 10%(11) Mac 2 5.16 5.08 11%(12) Mac 3 5.04 5.14 12*(13) Mya 1 5.69 5.03 13%(14) Mya 2 5.28 5.04 14%(15) Mya 3 5.15 5.13 15%(16) No organisms 1 5.61 5.20 20%(1) T0 SAMPLE T0 1 5.3260% 5.0094% 22% T0 2 5.1060% 5.0677% 23% T0 3 5.1855% 5.0531% 24% *cell nr 12 (Mac 3) – the internal standard was added twice (200 µl instead of 100 µl)
  • 51. 51"|"P a g e " % 9.6 APPENDIX F - Laboratory Techniques: The GC-MS Machine The Gas Chromatography – Mass Spectrometer (GC-MS) instrument is used for separating chemicals based on the ease with which they evaporate into a gas (change state from liquid to gas), and identifying them based on the structure they possess. The instrument is composed of two parts: the gas chromatography (GC) part that separates the chemical compounds into pulses of pure chemicals, and the mass spectrometer (MS) part that is used for identifying and quantifying the chemicals (OSU, 2013). Figure 22. The different components of the GC-MS machine The Gas chromatography unit of the machine is made up of three parts: - Injector – extracts the solvent from the GC-MS-vials and sends it to the GC. The needle of the injector extracts one microliter (1 !l) of the compound and injects in the GC from where the sample is propagated further by a non-reactive gas. The injector can be heated up to a temperature of 300℃ to change the phase of the solvent from liquid to gas. - Oven – represents the outer part of the GC unit. It contains the column, which is heated to enable the molecules of the analyzed chemicals to move through it. The oven can normally reach temperatures from 40℃ to 320℃ (OSU, 2013). - Column – is situated inside the oven and consists of a thin tube of varying lengths and thicknesses that is coated on the inside with a special polymer (polymer coating, length and
  • 52. 52"|"P a g e " % thickness depend on the type of chemical analyzed). The chemicals that undergo analysis are separated based on their volatility and are transported through the column with the help of the non-reactive gas. Chemicals that have high volatility propagate faster through the column than the ones that are characterized by low volatility (OSU, 2013). The volatility of any given substance is linked to the size of its molecules, as small molecules tend to propagate at higher speeds compared to larger molecules. The Mass Spectrometer unit consists of: - Ion source – once the chemical analyzed has passed through the GC, the resulting pulses go to the MS unit. The molecules are then broken into pieces, as they are blasted with electrons. This determines the molecules to lose, themselves, electrons and become positively charged particles (ions). These charged particles then continue their way to the filter. - Filter – the charged particles then pass through an electromagnetic field that uses the mass of the ions as a base for filtration. The desired range of masses (that will be able to pass through the filter) is chosen prior to the commencement of analysis. - Detector – quantifies the ions with the desired mass (target ions) and sends the collected information to a computer, which reinterprets it in the form of a mass spectrum. The mass spectrum is illustrated in the form of a graph that consists of a number of ions of different masses that have passed through the filter.
  • 53. 53"|"P a g e " % 9.7 Appendix G – Overall results Table 13. Overall results. From left to right: Treatment type, Initial AC concentration (added in the sediment), Measured AC concentration (at the end of the exposure period), Calculated AC concentration (based on dw), Dry weight, Wet weight, dw:ww ratio, Amount of sediment measured used for analysis (ww), Amount of sediment used for analysis (dw) Figure 23. Additional General Linear Model graphs: (left) Overall view of the To vs Tend samples; (right) Comparison between Tend samples.
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