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The Roles of Mangrove for Metal(loid)s Retention and Implication for Designing Payment for Forest Environmental Services (PFES) in Vietnam

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Presented by Dr. Nguyen Thanh Nho, Nguyen Tat Thanh University (NTTU) and Dr. Truong Van Vinh, Nong Lam University Ho Chi Minh City (NLU-HCM), on 10 November 2020 at "International workshop: Enhancing wetland management and sustainable development"

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The Roles of Mangrove for Metal(loid)s Retention and Implication for Designing Payment for Forest Environmental Services (PFES) in Vietnam

  1. 1. 11/16/2020 1 THE ROLES OF MANGROVE FOR METAL(LOID)S RETENTION AND IMPLICATION FOR DESIGNING PAYMENT FOR FOREST ENVIRONMENTAL SERVICES (PFES) IN VIET NAM NGUYEN THANH-NHO(1) và TRUONG VAN VINH (2) (1) Faculty of Environmental and Food Engineering, Nguyen Tat Thanh University (2) Faculty of Forestry, Nong Lam University Ho Chi Minh City
  2. 2. Mangroves are forests of salt-tolerant trees and shrubs, growing in the shallow tidal waters of estuaries and coastal areas, in the intertidal zones of tropical and subtropical regions. Mangroves? 2 Land Sea Nguồn: Selvam 2004
  3. 3. Mangrove distributions and characteristics? o Cover close to 140,000 km2. o extend from 30 0N to 38 0S. Characterized by: o High organic matter in soils. o High clay content in soils. 3 Global mangrove distribution map (2013). (http://www.mangrovewacth.org.au/index.php)
  4. 4. 4 Ecological benefits of Mangrove Source: https://savecaramoanpeninsula.wordpress.com/2014/06/18/importance-of-mangroves/
  5. 5. Mangrove environmental service in Vietnam? 11/16/2020 5 Mangrove environmental services in Vietnam for which a PFES mechanism can be developed (Pham và cộng sự 2020)
  6. 6. Sources and emission pathways of metal(loid)s 11/16/2020 6 Agricultural landscapes Weathering processes etc. Sewage, industrial effluents Urban and runoff Conceptual model of physical, chemical and biological variables and processes for behavior and toxicity of metal(loid)s. (Machado et al. 2016)
  7. 7. Why can mangrove be potential roles for metal(loid)s retention? 11/16/2020 7 => induce different biogeochemical processes, affecting trace metal(loid) distributions and partitioning. Classis estuarine zonation (Bianchi 2007). Estuarine waters are characterized by strong gradients in e.g. salinity, density, flow velocity, suspended matter composition.
  8. 8. Why can mangrove be potential roles for metal(loid)s retention? 11/16/2020 8 Alongi et al., 2014. Mangrove Estuary Sink of metal(loid)s Landward River Fine particle deposition Decrease in flow velocity Mangrove biota uptake Mangrove sediments are characterized by different redox processes. => Trace metals bearing phases may be dissolved.
  9. 9. Which method can be used to prove the role of mangrove for metal(loid)s trapping? 11/16/2020 9 Two main questions need to be answered: 1. How to confirm and prove that mangrove can trap metal(loid)s in water? 2. What method can be used to determine and demonstrate?
  10. 10. Method can be used to prove the role of mangrove for metal(loid)s trapping? 11/16/2020 10 Sampling sites: - Sites are considered as input and output of contaminants that have mangrove and without mangrove, respectively. - Site is located at the river mouth. Control sites (i.e. input of mangrove) Intervention sites (within the mangrove or without mangrove) Control site (output of mangrove or river mouth)
  11. 11. 11/16/2020 11 Sample collection: Samples Filtrate and Suspended particulate matter Surface sediment Mangrorve sediment Mangrove tissues Method can be used to prove the role of mangrove for metal(loid)s trapping?
  12. 12. Case study in Hai Phong city 11/16/2020 12 Where: Control sites: 1, 4, 7 Intervention sites: 2, 3, 5, 6 Sampling sites expressing in yellow: mangrove-dominated area (Da Bac-Bach Dang River) Sampling sites expressing in red: without mangrove area (Cam River)
  13. 13. Case study in Hai Phong City 11/16/2020 13 Water filtration to collect filtrate and suspended particulate matter Sampling surface sediment Sampling mudflat to mangrove sediment Sampling at field
  14. 14. Case study in Hai Phong City 11/16/2020 14 Temporal variation of total metal(loid) concentration in water At both tributaries: Concentrations of metal(loid)s at intervention sites were higher than those measured at control sites.  Site 1, 2 and 3: Cam River  Site 4, 5 and 6: Da Bac-Bach Dang River
  15. 15. Case study in Hai Phong city 11/16/2020 15 At both tributaries: Concentrations of metal(loid)s at intervention sites were higher than those measured at control sites.  Site 1, 2 and 3: Cam River  Site 4, 5 and 6: Da Bac-Bach Dang River
  16. 16. Case study in Hai Phong city 11/16/2020 16 Mangrove-dominated area: Da Bac- Bach Dang River: Concentrations of metal(loid)s at output of mangrove (Site 6) were lower than those measured at input site (Site 5). => Potential role of mangrove for contaminant reduction  Site 1, 2 and 3: Cam River  Site 4, 5 and 6: Da Bac-Bach Dang River
  17. 17. dy in Hai Phong city 11/16/2020 17 Map of distribution of different industries in Hai Phong (Note: this distribution is compiled of companies with location data on Google Maps) =>Higher concentrations at site 5 than site 6 could be caused by iron and steel production, shipbuilding industry, and charcoal port 5 6 Sampling site
  18. 18. Case study in Hai Phong city 11/16/2020 18 Interventions sites at without mangrove area: Cam River: Concentrations of metal(loid)s at intervention sites (Site 3) were higher than those measured at Site 2.  Site 1, 2 and 3: Cam River  Site 4, 5 and 6: Da Bac-Bach Dang River
  19. 19. dy in Hai Phong city 11/16/2020 19 => Increasing of metal(loid) concentration can be orginated from iron and steel facilities, port, and Shipbuilding activities. 2 3 Sampling site Map of distribution of different industries in Hai Phong (Note: this distribution is compiled of companies with location data on Google Maps)
  20. 20. Case study in Hai Phong city 11/16/2020 20 Metal(loid) concentrations in surface sediment Concentration of metal(loid)s in order of: Al > Fe > Mn > Zn > Cr > Pb > Cu > Ni > As> Cd  Within the range of concentration measured in other River in Vietnam:  Sai Gon River (Strady et al. 2017)  Thi Vai River (Costa-Boddeker et al. 2017)
  21. 21. Enrichment Factor (EF) 𝑀𝑒 𝑠𝑜𝑖𝑙, 𝐴𝑙 𝑠𝑜𝑖𝑙: concentration of metal(loid) and aluminium in sediment 𝑀𝑒 𝑐𝑟𝑢𝑠𝑡, 𝐴𝑙 𝑐𝑟𝑢𝑠𝑡 concentration of metal(loid) and aluminium in crust surface (Wedepohl 1995) Level Value Caterogisation 0 1 2 3 4 5 6 EF ≤ 1 1 ≤ EF ≤ 3 3 ≤ EF ≤ 5 5 ≤ EF ≤ 10 10≤ EF ≤ 25 25 ≤EF ≤ 50 50≤ EF No enrichment Minor enrichment Moderate enrichment Moderately severe enrichment Severe enrichment Very severe enrichment Extremely severe enrichment 𝐸𝐹 = ( 𝑀𝑒 [𝐴𝑙] ) 𝑠𝑜𝑖𝑙 ( 𝑀𝑒 [𝐴𝑙] ) 𝑐𝑟𝑢𝑠𝑡 Natural or anthropogenic source Wedepohl, K.H., The composition of the continental crust. Geochimica et cosmochimica Acta, 1995. 59(7): p. 1217-1232. 11/16/2020
  22. 22. Case study in Hai Phong city 11/16/2020 22 Enrichment Factor of metal(loid)s in surface sediment - Fe, Mn, Ni, Cu và Zn: 1 < EF< 3 (Minor enrichment). - Cd và Pb: 3 < EF < 10 (Moderate to moderately severe enrichment). - Notably, As: 10 < EF < 25: Severe enrichment. Most of metal(loid)s may originate from anthropogenic activities
  23. 23. Index of Geo-accumulation (Igeo) 𝐼𝑔𝑒𝑜 = log2 𝐶 𝑛 𝐵𝑛 × 1.5 𝐶 𝑛: Metal(loid) concentration in sediment 𝐵𝑛: the background value for the metal n 1.5 is used because of possible variation in background data due to lithological variation Level Value Quantification 0 1 2 3 4 5 6 𝐼𝑔𝑒𝑜 ≤ 0 0 ≤ 𝐼𝑔𝑒𝑜 ≤ 1 1 ≤ 𝐼𝑔𝑒𝑜 ≤ 2 2 ≤ 𝐼𝑔𝑒𝑜 ≤ 3 3 ≤ 𝐼𝑔𝑒𝑜 ≤ 4 4 ≤ 𝐼𝑔𝑒𝑜 ≤ 5 5 < 𝐼𝑔𝑒𝑜 Uncontaminated Uncontaminated to moderately contaminated Moderately contaminated Moderately to heavily contaminated Heavily contaminated Heavily to extremely contaminated Extremely contaminated Any increase can be caused by human impact 11/16/2020
  24. 24. Case study in Hai Phong city 11/16/2020 24 - Cu, Zn, Cd and Pb: 0 < Igeo< 2: moderately contaminated - Notably, As: 3 < Igeo: Heavily contaminated Index of Geo-accumulation in surface sediment Most of metal(loid)s were caused by human activities
  25. 25. Case study in Hai Phong city 11/16/2020 25 Metal stock (t ha-1) = (Csediment * BD * 50 * 100)/106 where: Ctrầm tích: average total metal(loid) concentration in the upper 50 cm (mg kg-1) BD: average bulk density in the upper 50 cm (g cm-3) 50: length of the cores used for estimation of metal(loid) stock (cm) 100: conversion factor from g cm-2 sang t ha-1 106: conversion factor of a metal(loid) concentration in mg kg-1
  26. 26. Case study in Hai Phong city 11/16/2020 26  Most of metal(loid) stocks increased from mudflat to the mangrove stand.  Exept Mn, its stock was lower in the mangrove stand than other one. Why??? Concentration of : Al > Fe > Mn > Zn > Cr ~ Pb > Cu ~ Ni > As > Cd
  27. 27. Case study in Hai Phong city 11/16/2020 27 Most of metal(loid) stocks increased from mudflat to the mangrove stand.
  28. 28. 11/16/2020 28 Metal(loid) accumulation in mangrove tissues Leaf Root Interface between sediment-air 50 cm of sediment depth Saplings Mature trees Saplings Mature trees Bioconcentration factor (BCF) = Ctissue/ Csediment Case study in Hai Phong city
  29. 29. 11/16/2020 29 => Mn was accumulated at high concentration in different parts of mangrove, notably in leaf. Bioconcentration factor (BCF) = Ctissue/ Csediment Case study in Hai Phong city
  30. 30. 11/16/2020 30 Summary  Mangrove acts as natural sink that stores and contributes for reducing metal(loid) contaminants in water flowing through its system.  The method applied in the Hai Phong city can be deployed to other areas in Vietnam.  The results indicated that iron and steel manufacturing facilities, shipbuilding, coal ports and ship ports can be main sources of metal(loid) emissions. Protection of mangrove should be strengthened to enhance the value of their ecological services. It is necessary to develop a policy of payment for metal(loid) contaminant reduction/ self-cleaning services to fund the conservation and expansion of mangrove. Case study in Hai Phong city
  31. 31. 11/16/2020 31

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