es301328r_si_001.pdf (1.66 MB)
Spatial Heterogeneity and Kinetic Regulation of Arsenic Dynamics in Mangrove Sediments: The Sundarbans, Bangladesh
journal contribution
posted on 2016-02-20, 14:00 authored by Mahmud Hossain, Paul N. Williams, Adrien Mestrot, Gareth
J. Norton, Claire M. Deacon, Andrew A. MehargThe 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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Sundarban mangrove ecosystemsArsenic DynamicsOMdiffusive gradientssediment depositional environmentssediment binding characteristicsresupplySundarbans locationsDOMfield monitoringDGTforest biomassparticle sizeBengal Deltamatter content forest floor sedimentsBangladeshThe biogeochemistrymangrove ecosystemKinetic Regulationsurface waterDepositional environmentsediment coresoverbank verses forest floorMangrove SedimentsSpatial HeterogeneitySediment cores
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