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Understanding small-scale features in DGT measurements in sediments.

Sochaczewski, Łukasz and Davison, William and Zhang, Hao and Tych, Wlodek (2009) Understanding small-scale features in DGT measurements in sediments. Environmental Chemistry, 6 (6). pp. 477-485. ISSN 1448-2517

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Abstract

Measurements in sediments made using DGT (diffusive gradients in thin-films) have shown small-scale (millimetre and sub-millimetre) maxima in solute concentration (e.g trace metals and sulfide). The sediment–DGT system was simulated using a dynamic model, which incorporated a spherical microniche close to the DGT surface. DGT maxima could arise when the microniche was (1) a local source with associated elevated concentration in the pore water, and (2) when, within the microniche, the Kd for the relevant solute partitioning with exchangeable solute associated with the solid phase was much higher than for the rest of the sediment. Use of realistic values of Kd and comparison with existing data suggested that the latter mechanism was unlikely to be responsible for observed DGT maxima. Locally elevated concentrations will be reasonably accurately reproduced by DGT. Peak height measured by DGT will be between 62 and 87% of the true maxima in concentration within the sediment when DGT is not present, while peak widths will be similar. This work provides, for the first time, a means for confidently interpreting the two dimensional images of DGT-measured concentrations in sediments.

Item Type: Article
Journal or Publication Title: Environmental Chemistry
Uncontrolled Keywords: microniche ; sulfide ; trace metals
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 40765
Deposited By: Mr Richard Ingham
Deposited On: 03 May 2011 15:13
Refereed?: Yes
Published?: Published
Last Modified: 06 Sep 2013 20:46
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/40765

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