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Heavy metal contamination of global environment

The term heavy metal refers to any metallic chemical element that has a relatively high density and is toxic or poisonous at low concentrations.
Heavy metals are Globally distributed

Heavy metal contamination of global environment

  1. 1. Heavy metal Contamination of Global Environment Presented by Dr. B. Victor., Ph. D Email : Blog:
  2. 2. Environmental disasters – Heavy metal contamination1932-1952 MinamataSewage containing mercury is released by Chissos chemicals works into Minimata Bay in Japan. The mercury accumulates in sea foods.In 1952, the consumption of fish polluted with mercury, caused nearly 1000 fatalities.1986-11-01 SandozWater used to extinguish a major fire carries fungicide containing mercury into the Upper Rhine. Fish are killed over a stretch of 100 km.1998-04 Disaster at Spanish nature reserve Toxic metals in water from a burst dam of a mine waste containing sulphur, lead, copper, zinc and cadmium flow down the Rio Guadimar in southern Spain. Spanish nature reserve was permanently damaged after this environmental disaster.
  3. 3.  Definition, kinds and physical properties  Bioactivity and target organ toxicityPresentation  Sources and toxicologicout line properties  Environmental fate of metals  Toxicologic diseases  Mercury, Cadmium, lead, chromium, arsenic, cobalt, and zinc contamination – sources, fate and human health effects.  Conclusion
  4. 4.  The term heavy metal refers to any metallic chemical element that has a relatively high density and is toxic orWhat is a poisonous at lowheavy metal ? concentrations.  Heavy metals are conventionally defined as elements with metallic properties and an atomic number >20.  The most common heavy metal contaminants are Cd, Cr, Cu, Hg, Pb, and Zn.
  5. 5. Physical properties of metals Good conductors of heat and High density electricity Non- (heavy for degradable their size) Malleable : High melting hammered point into thin sheets Physical Ductile: Lustre drawn out intoshininess Properties thin wires of metals
  6. 6. Kinds of metals • lithium (Li), sodium (Na), potassiumAlkali metals (K), rubidium (Rb), caesium (Cs).Alkaline earth • beryllium (Be) magnesium (mg), calcium (Ca), strontium (Sr), barium metals (Ba) and radium (Ra). • boron, silicon, germanium, arsenic, Metalloids antimony, tellurium, and polonium • platinum, silver and gold. copper (Cu), nickel (Ni), chromium (Cr) and ironHeavy metals (Fe) cadmium (Cd), lead (Pb), silver (Ag) and mercury (Hg)
  7. 7. Heavy metalsMacro-nutrient • cobalt (Co), copper (Cu) elements • zinc (Zn) and iron (Fe).Micronutrient • copper (Cu), nickel (Ni), elements • chromium (Cr) and iron (Fe) Highly toxic • cadmium (Cd), lead (Pb), elements • silver (Ag) and mercury (Hg) Precious • platinum, silver and gold elements
  8. 8. DefinitionHeavy metal• Refers to any metallic chemical element that has a high specific gravity and high relative atomic mass.
  9. 9. Metals • Iron, zinc, copper, chromium, cobalt Essential • Molybdenum, selenium • Silicon, manganese beneficial • Nickel, boron, vanadium • Mercury,cadmium,Detrimental • lead • Arsenic, chromium
  10. 10. Distinguishing properties of metals Conservative Pollutants : Chemical Effectively time bombs permanent Globally Immutabledistributed pollutantspollutants Heavy metals
  11. 11. Biological activity of metals Inhibit enzymes Inhibit synthesis of proteins Cross membranes by passive diffusion/pinocytosis Target /critical organ for most metals-kidney
  12. 12. Target organ toxicity of metals Zinc blood hemotoxicity Arsenic liver hepatotoxicity Mercury brain neurotoxicity Lead cadmium Kidney lungs Nephrotoxicity pulmonotoxicity
  13. 13. Sources of heavy metal pollutants Mining Agriculture Smelting & forestry Sources Fossil fuel Metallurgical combustion industries Waste Corrosion disposal
  14. 14. Toxicological properties of heavy metals Persistence-long Acute Toxicity- Soil residence residual and half plants, animals, time ->1000 years life microorganisms , Bioaccumulation Chronic and sub- and lethal effects at Synergistic effects biomagnification- low conc. thro’ food chain Teratogenic and carcinogenic properties
  15. 15. Fate of heavy metalsAnthropogenic and Industrial activities Waste metal pollutants (Volatilization, Leaching) Environment- ecological effects Human system- exposure via food intake, water consumption, ingestion, dermal contact, inhalation. Human health effects
  16. 16. Fate of metals in aquatic environment more soluble precipitate in at high hard water. temperature. Benthic organisms accumulate soluble in thro. acidic water Food chain aquatic Insoluble organisms take metals up from water or sediments deposit in the via eating or river respiration sediments
  17. 17. Toxic diseases of heavy metals Aluminium has been associated with Arsenic exposure can Cadmium exposure Alzheimers and cause cancer, produces kidney Parkinsons disease, abdominal pain, and damagesenility, and presenile black foot disease. and hypertension dementia.Lead and mercury may cause joint diseases Nickel can cause Chromium can cause and ailments of the damage to lung, liver lung damage and kidneys, circulatory and kidney. cancer. system, and nervous system
  18. 18. Mercury contaminationAll forms of mercury arepoisonousMercury is persistent and cyclesgloballyContinues to be widely usedCan be toxic to CNS, lungs andkidneys
  19. 19. Hg as Toxic contaminant Most Potent Oldest poison neurotoxicant Developmental toxicant fetotoxic
  20. 20. Sources of mercury contamination AnthropogenicNatural sources inadvertent sources Volcanic eruptions  Mercury mining, smelting and use. Rock weathering  Burning fossil fuels Natural fires  Coal-fired power plantsAnthropogenic intentional  Municipal / medicalsources waste incineration• Folk medicines  Cement production• Cosmetics  Chlorine-alkali• Dental amalgams production• Vaccines
  21. 21. History of mercury poisoningsMinamata Bay, Japan In the 1950’s, large amounts of organic mercury were dumped into Minamata Bay in Japan. Mercury-contaminated fish were consumed by pregnant women. many children that were born from these women had severe nerve damage. later referred as Fetal Minamata Disease.Iraq children born to mothers who consumed grain contaminated with organic mercury, the effects showed the children walking at a later age than non-exposed children.Faroe Islands Mercury exposure was caused by contaminated whale meat. Children born to mothers with high body levels of mercury scored lower on brain function tests than mothers with low body levels.
  22. 22. Forms of mercury • ‘Quick silver’, natural Elemental mercury element, • Silver white, odorless liquid • Mer-curic / Inorganic curous mercury chloride salts • Mercury cyanide Organic • Methyl/ ethyl mercury mercury compounds • phenyl mercury
  23. 23.  The most dangerous form ofMethyl mercury.mercury  Hg bio-transformed in sediments into methyl mercury by aquatic microbes.  Bio-accumulate thro’ aquatic food chain in larger predatory fishes-tuna, mackerel, shark, grouper  Bio-persistent, lipophilic, crosses placenta and the blood-brain barrier., concentrates in CNS.  Tightly bound to fish proteins.  Enter human body thro’ fish consumption.
  24. 24. Human  Breathing air containingexposure to mercury vaporsmercury  Drinking water contaminated with mercury.  Eating fish or shell fish contaminated with mercury.  Touching liquid mercury in the event of a spill.
  25. 25. Health effects of mercury Disruption of the central nervous system Damage to brain, lungs and kidneys Damage to chromosomes and DNA. Allergic reactions, resulting in skin rashes, tiredness headaches and vision problems. Negative reproductive effects, such as sperm damage, birth defects and miscarriages
  26. 26. Cadmium contamination Accumulates in liver and kidneysHighly toxic Potent Non- enzyme essential inhibitor Cadmium
  27. 27. Sources of cadmium contamination Mining and metallurgical operations Electroplating industry Manufacturing PVC plastics Ni-Cd batteries, paints , pigments and dyes Fertilizers and pesticides Anti-corrosive agent for steel, iron, copper, brass and other alloys. Photo voltaic devices and TV screens.
  28. 28. Human health effects Cause diarrhoea, stomach pains and severe vomiting Itai- itai disease-bone fracture Kidney dysfunction-chronic renal failure Reproductive failure and even infertility Damage to the central nervous system Damage to the immune system Psychological disorders DNA damage or cancer development
  29. 29. Environmental effects of cadmium Cadmium -rich sludge can pollute surface waters as well as soils. Cadmium strongly adsorbs to organic matter in soils. Soils that are acidified enhance the cadmium uptake by plants. Cadmium can accumulate in the plant eating animals , especially when they eat multiple plants. In aquatic ecosystems, cadmium can bioaccumulate in mussels, oysters, shrimps, lobsters and fish.
  30. 30. Lead contamination General Metabolic poison Non-Cumulative essentialneurotoxin element Lead
  31. 31. Lead – Pb-contaminant Atomic Atomic weight Number 207.19 82 Specific gravity Melting point 11.34 327.5 o C Boiling point Bluish-grey 1740 0 C metal
  32. 32. Sources of lead contamination Industrial discharges from smelters and battery manufacturing units Solders in electronics Sewage effluent Atmospheric fallouts from fossil fuel burning building industry for roofing and flashing and for soundproofing Used in paints Used in pipes, ceramics and dishware Ammunition Lead is used in batteries and sinkers in fishing
  33. 33. Human health effects A general metabolic poison Acute exposure –kidney damage Chronic exposure – interstitial nephritis of kidney Inhibits haemoglobin synthesis and cause anemia Inhibits enzyme activity Neurological and reproductive dysfunctions Lead poisoning (also known as plumbism, colica pictonium, saturnism, painters colic) is a medical condition. Lead breaks the blood-brain barrier and interferes with the normal development of brain in infants
  34. 34. Environmental contamination of Lead Approx. 94% of the Pb in the atmosphere is derived from heavy motor traffic in urban areas. The aerial dispersion may lead to higher levels of Pb in rivers, seas and soils. Lead gets into soil through paint, dry and wet depositions from the atmosphere and industrial effluents and solid discharges. Lead combine with colloidal particles found in natural water. Urban run off cause pollution of surface and ground water. Consumption of such untreated water may lead to Pb poisoning.
  35. 35. Chromium - Cr Chromium is an abundant element of earth’s crust. The trivalent (III) and hexavalent (VI)compounds of chromium are great industrial importance. Chromium(III) is an essential nutrient.
  36. 36. Human health effects of chromium Acute chromium toxicity cause renal tubular necrosis. Chronic chromium toxicity cause cancers of respiratory tract. Upset stomachs and ulcers Respiratory problems-lung cancer Weakened immune system Kidney and liver damage Teratogenic and carcinogenic action Death
  37. 37.  Chromium in air will eventually settle and end up in waters orEnvironmental soilseffects ofchromium  Chromium in soils adsorbs to soil particles and percolates to ground water  Chromium may adsorb on sediments and become immobile in water .
  38. 38. Arsenic contamination Cumulative poison carcinogen Trivalent A toxic, non- arsenites areessential, semi- more toxic than metallic pentavalent element arsenates Arsenic
  39. 39.  Pesticides, herbicides  Combustion of coal  Mining, smelting of gold,Sources of lead, copper and nickelArseniccontamination  Production of iron and steel  Leachate from abandoned gold mines  A wood preservative  Tobacco smoke
  40. 40.  Birth defects  Carcinogen: Lung cancer, Skin and liver cancer,Human health cancers of the bladder andeffects kidneys  Gastrointestinal damage  Severe vomiting  Diarrhea  Death
  41. 41.  Cobalt has a melting point ofCobalt 1495oC, boiling point of 2870oC,contamination specific gravity of 8.2 g/cm3 at 20oC, atomic number of 27, atomic weight of 58.933 g/mol.  Cobalt is hard, ductile and lustrous bluish-grey in color.  Cobalt is an essential element. It is an integral component of vitamin B12. It is therefore required for good health.
  42. 42.  Manufacture of many alloys used in gas turbine, aircraft engines, corrosion resistant alloys, high speed steels and cemented carbides.  As catalysts for the petroleum andUses of cobalt chemical industries  As drying agents for paints and inks  Used as pigment in porcelain, pottery, glass, tiles, and enamel jewellery.  Radioactive isotopes, cobalt-60, is used in medical treatment and for food preservation  Treatment of anemia
  43. 43.  Mining and refining of cobalt  Production of alloys  Production of tungsten carbideSources of  Jewellery producerscobalt  Ceramics, porcelain producers  Metallurgical industries
  44. 44.  Cobalt stimulates the production of red blood cells, thus, used to treat anemia. At high concentration mayHuman damage human effects  In soil, it may adsorb on soilof cobalt particles and is only mobilized under acidic condition. Cobalt is also adsorbed on sediments.  Cobalt may accumulate in plants and in the bodies of animals that eats these plants. Cobalt is not known to bio-magnify up to the food chain.
  45. 45.  Zinc is a lustrous bluish-white metal whose atomic number and atomic mass are 30 and 65.37 g/mol respectively.Zinc  The density is 7-11 g/cm3 at 20oC withcontamination melting and boiling points at 420oC and 907oC respectively.  zinc is brittle and crystalline at room temperature but becomes ductile and malleable between 110oC and 150oC.  It is used for galvanizing steel and in the preparation of alloys.
  46. 46. Uses of zincZinc is used as the negative plates in batteries.Zinc is utilized for roofing in building construction.Zinc oxides is used as a white pigment in paints.Zinc is used as pigment in plastic ,cosmetics, photocopier paper, wallpaper, printing inks.Zinc is utilized as a catalyst during rubber production.Zinc is used as drugs, as anti-oxidants and protect against premature aging of the skin and muscle of the body.
  47. 47. Occurrence of zinc Zinc is the most abundant element in the earth crust. It occurs naturally in air, water and soil. Zinc is an essential trace element required for the function of over 200 metallo-enzymes. Zinc is also important in the regulation of DNA and RNA synthesis via interaction with DNA binding protein. It also plays a critical role in hormone-receptor interaction
  48. 48.  Loss of appetite and fatigueHuman health  Decreased sense of taste and smelleffects of zinc  Slow wound healing  Skin sores  Stomach cramps  Nausea and vomiting  Anemia  Respiratory disease  Eye irritation  High exposure damage the pancreas  Birth defect
  49. 49. Environmental effect of zinc Zinc in water (from wastewater of industrial plants) increases the acidity of waters. Some fish can bio-accumulate Zn in their bodies. Zinc in fish can bio-magnify and enter human food chain. Insoluble zinc in soils can contaminate groundwater.
  50. 50.  Dr.B.Victor is a highly experienced professor, recently retired from the reputed educational institution- St. Xavier’ s College, Palayamkottai, India-627001. He was the dean of sciences, IQAC coordinator and assistant controller of examinations. He has more than 32 years of teaching and research experience He has taught a diversity of college courses and guided 12 Ph.D scholars. Send your comments to :
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The term heavy metal refers to any metallic chemical element that has a relatively high density and is toxic or poisonous at low concentrations. Heavy metals are Globally distributed pollutants


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