Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Localised remobilisation of metals in a marine sediment.
AU - Zhang, Hao
AU - Davison, William
AU - Mortimer, Robert
AU - Krom, Michael D.
AU - Hayes, Peter J.
AU - Davies, Ian M.
PY - 2002/9/16
Y1 - 2002/9/16
N2 - Trace metals and Fe and Mn were measured at vertical spatial resolutions of 2.5 and 5 mm in the top 35 cm of the profundal sediment of a Scottish sea-loch using DGT (diffusive gradients in thin films) technique. DGT probes lower adjacent metal concentrations in pore waters and induce a flux of metal from the solid phase to porewater. The concentrations of metals in porewaters at the interface of the probe were measured during its deployment in a box core. These measurements reflect porewater concentrations of metals and their rates of resupply from the local solid phase of a very small volume (25 μl) of sediment. There was pronounced horizontal and vertical structure in the interfacial concentrations. Horizontal variations were shown by results from adjacent DGT assemblies being markedly different in detail, while vertical structure was measured directly by the DGT-depth profiles. Iron and Mn varied systematically with depth, with both broad and detailed features of Co aligning with those of Mn. There was, however, evidence of additional localised sources of Co that were apparently unrelated to the redox behaviour that Mn typifies, but associated with the remobilization of Ni, possibly from mineral dissolution. Arsenic(III) was remobilized in well-defined zones. Detailed correspondence of As(III) with some Fe features suggest that its release is mechanistically-related to iron oxide dissolution, but the 3 orders of magnitude higher concentrations of Fe may sometimes obscure the association. These results demonstrate that, within sediments, metals may be released in discrete locations that are not measured by conventional porewater sampling techniques due to their horizontal averaging.
AB - Trace metals and Fe and Mn were measured at vertical spatial resolutions of 2.5 and 5 mm in the top 35 cm of the profundal sediment of a Scottish sea-loch using DGT (diffusive gradients in thin films) technique. DGT probes lower adjacent metal concentrations in pore waters and induce a flux of metal from the solid phase to porewater. The concentrations of metals in porewaters at the interface of the probe were measured during its deployment in a box core. These measurements reflect porewater concentrations of metals and their rates of resupply from the local solid phase of a very small volume (25 μl) of sediment. There was pronounced horizontal and vertical structure in the interfacial concentrations. Horizontal variations were shown by results from adjacent DGT assemblies being markedly different in detail, while vertical structure was measured directly by the DGT-depth profiles. Iron and Mn varied systematically with depth, with both broad and detailed features of Co aligning with those of Mn. There was, however, evidence of additional localised sources of Co that were apparently unrelated to the redox behaviour that Mn typifies, but associated with the remobilization of Ni, possibly from mineral dissolution. Arsenic(III) was remobilized in well-defined zones. Detailed correspondence of As(III) with some Fe features suggest that its release is mechanistically-related to iron oxide dissolution, but the 3 orders of magnitude higher concentrations of Fe may sometimes obscure the association. These results demonstrate that, within sediments, metals may be released in discrete locations that are not measured by conventional porewater sampling techniques due to their horizontal averaging.
KW - Diffusive gradients in thin films
KW - DGT
KW - Metals
KW - Porewaters
KW - Sediment
KW - Fluxes
KW - Remobilization
KW - Microniche
U2 - 10.1016/S0048-9697(02)00078-5
DO - 10.1016/S0048-9697(02)00078-5
M3 - Journal article
VL - 296
SP - 175
EP - 187
JO - Science of the Total Environment
JF - Science of the Total Environment
SN - 0048-9697
IS - 1-3
ER -