Publication Date:
2011-06-10
Description:
A field and laboratory study of the accuracy of a method commonly used to determine free sulphide concentrations in the porewater of marine sediments is presented. The method uses an ion-selective electrode (ISE), sensitive to the sulphide ion (S 2− ), in sediments buffered to high pH (〉12) and is commonly used in regulatory monitoring programs to assess the impacts of open net-pen finfish aquaculture on local marine habitats. Here we report that on the timescale of field measurements, the accepted protocol can lead to significant bias of free sulphide measurements, with orders of magnitude higher concentration detected in the buffered sediment–porewater slurry than in porewater samples isolated and analysed separately. Laboratory experiments with model marine sediments and analysis of sediment composition indicate that this bias is likely introduced by the dissolution of particulate sulphides and/or sulphur present in the sediments under the intense alkaline conditions of the protocol. Recommendations for the modification and continued use of this commonly applied field methodology are discussed. Content Type Journal Article Pages 1-19 DOI 10.1007/s10498-011-9137-0 Authors Kristina A. Brown, University of Victoria, School of Earth and Ocean Sciences, Bob Wright Centre, Victoria, BC, Canada Eric R. McGreer, Environmental Protection Division, British Columbia Ministry of Environment, Nanaimo, BC V9T 6J9, Canada Bernie Taekema, Environmental Protection Division, British Columbia Ministry of Environment, Nanaimo, BC V9T 6J9, Canada Jay T. Cullen, University of Victoria, School of Earth and Ocean Sciences, Bob Wright Centre, Victoria, BC, Canada Journal Aquatic Geochemistry Online ISSN 1573-1421 Print ISSN 1380-6165
Print ISSN:
1380-6165
Electronic ISSN:
1573-1421
Topics:
Chemistry and Pharmacology
,
Geosciences
