Spatial heterogeneity and kinetic regulation of arsenic dynamics in mangrove sediments

the Sundarbans, Bangladesh

Mahmud H. Sumon, Paul N. Williams, Adrian Mestrot, Gareth J. Norton, Claire M. Deacon, Andrew A. Meharg

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

The biogeochemistry of arsenic (As) in sediments is regulated by multiple factors such as particle size, dissolved organic matter (DOM), iron mobilization, and sediment binding characteristics, among others. Understanding the heterogeneity of factors affecting As deposition and the kinetics of mobilization, both horizontally and vertically, across sediment depositional environments was investigated in Sundarban mangrove ecosystems, Bengal Delta, Bangladesh. Sediment cores were collected from 3 different Sundarbans locations and As concentration down the profiles were found to be more associated with elevated Fe and Mn than with organic matter (OM). At one site chosen for field monitoring, sediment cores, pore and surface water, and in situ diffusive gradients in thin films (DGT) measurements (which were used to model As sediment pore-water concentrations and resupply from the solid phase) were sampled from four different subhabitats. Coarse-textured riverbank sediment porewaters were high in As, but with a limited resupply of As from the solid phase compared to fine-textured and high organic matter content forest floor sediments, where porewater As was low, but with much higher As resupply. Depositional environment (overbank verses forest floor) and biological activity (input of OM from forest biomass) considerably affected As dynamics over very short spatial distances in the mosaic of microhabitats that constitute a mangrove ecosystem.
Original languageEnglish
Pages (from-to)8645-8652
Number of pages8
JournalEnvironmental Science & Technology
Volume46
Issue number16
DOIs
Publication statusPublished - 21 Aug 2012

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Arsenic
mangrove
arsenic
Sediments
kinetics
Kinetics
sediment
Biological materials
porewater
forest floor
organic matter
depositional environment
Ecosystems
sediment core
mobilization
Biogeochemistry
regulation
ecosystem
biogeochemistry
Bioactivity

Cite this

Spatial heterogeneity and kinetic regulation of arsenic dynamics in mangrove sediments : the Sundarbans, Bangladesh. / Sumon, Mahmud H.; Williams, Paul N.; Mestrot, Adrian; Norton, Gareth J.; Deacon, Claire M.; Meharg, Andrew A.

In: Environmental Science & Technology, Vol. 46, No. 16, 21.08.2012, p. 8645-8652.

Research output: Contribution to journalArticle

Sumon, Mahmud H. ; Williams, Paul N. ; Mestrot, Adrian ; Norton, Gareth J. ; Deacon, Claire M. ; Meharg, Andrew A. / Spatial heterogeneity and kinetic regulation of arsenic dynamics in mangrove sediments : the Sundarbans, Bangladesh. In: Environmental Science & Technology. 2012 ; Vol. 46, No. 16. pp. 8645-8652.
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AB - The biogeochemistry of arsenic (As) in sediments is regulated by multiple factors such as particle size, dissolved organic matter (DOM), iron mobilization, and sediment binding characteristics, among others. Understanding the heterogeneity of factors affecting As deposition and the kinetics of mobilization, both horizontally and vertically, across sediment depositional environments was investigated in Sundarban mangrove ecosystems, Bengal Delta, Bangladesh. Sediment cores were collected from 3 different Sundarbans locations and As concentration down the profiles were found to be more associated with elevated Fe and Mn than with organic matter (OM). At one site chosen for field monitoring, sediment cores, pore and surface water, and in situ diffusive gradients in thin films (DGT) measurements (which were used to model As sediment pore-water concentrations and resupply from the solid phase) were sampled from four different subhabitats. Coarse-textured riverbank sediment porewaters were high in As, but with a limited resupply of As from the solid phase compared to fine-textured and high organic matter content forest floor sediments, where porewater As was low, but with much higher As resupply. Depositional environment (overbank verses forest floor) and biological activity (input of OM from forest biomass) considerably affected As dynamics over very short spatial distances in the mosaic of microhabitats that constitute a mangrove ecosystem.

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