Title
The impact of increased oxygen conditions on metal-contaminated sediments part 1 : effects on redox status, sediment geochemistry and metal bioavailability The impact of increased oxygen conditions on metal-contaminated sediments part 1 : effects on redox status, sediment geochemistry and metal bioavailability
Author
Faculty/Department
Faculty of Sciences. Biology
Publication type
article
Publication
Oxford ,
Subject
Chemistry
Biology
Source (journal)
Water research / International Association on Water Pollution Research. - Oxford, 1967, currens
Volume/pages
46(2012) :7 , p. 2205-2214
ISSN
0043-1354
ISI
000302645300018
Carrier
E
Target language
English (eng)
Full text (Publishers DOI)
Affiliation
University of Antwerp
Abstract
In order to evaluate the effect of improved oxygen concentrations in overlying surface water on the redox status, sediment geochemistry and metal bioavailability in metal-polluted sediments a 54 days lab experiment with two different experimental treatments was conducted (90% and 40% O2). Changes in redox potential (Eh) in the sediment were monitored over time. At 6 different time points (after 0, 2, 5, 12, 32 and 54 days) and at 4 sediment depths (01, 14, 48 and 815 cm), acid volatile sulfides (AVS), simultaneously extracted metals (SEM) and total organic carbon (TOC) were measured and metal release to overlying surface water was determined. Labile metal species in both water and sediment were measured using Diffusive Gradients in Thin films (DGT). Our results showed that elevated oxygen levels in overlying surface water led to an Eh increase in the sediment of the 90% O2 treatment from 0 to ±200 mV while AVS concentrations in the upper sediment layer decreased by 70%. Following AVS oxidation metal availability in the pore water was highly elevated after 54 days. However, Cu remained strongly bound to the sediment during the whole experiment. Only a limited metal release to the overlying surface water was noticed, which was due to the fact that SEMtot concentrations in the sediment did not yet exceeded AVS levels ([SEMtot − AVS]/fOC = 0) after 54 days. Additionally, adsorption on Fe and Mn hydroxides and particulate organic carbon also slowed down any potential metal release. Our results indicated that increasing oxygen concentrations due to general water quality improvements can enhance the mobility of trace metals which may result in the leaching of sediment-bound metals to overlying surface water, even in undisturbed watercourses.
E-info
https://repository.uantwerpen.be/docman/iruaauth/b67b0e/1e496b817e7.pdf
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