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Communication dans un congrès

Arsenic mobility in marine sediments: determination of thioarsenical compounds in porewaters

Abstract : The objective of ASEDMAR project is to develop a model combining geochemistry, bioavailability and ecotoxicity of arsenic in marine sediments contaminated by human activities. It was previously shown that arsenic in pore waters of marine sediment is mainly present as thioarsenical compounds and classical As forms (As(III), As(V) and methylated forms) remain generally low. Pore water playing an important role in the transfer of arsenic from sediment to the water column, its characterization in terms of As species is essential to better understand and model the bacterial cycle of arsenic, which is not very well known in marine ecosystem. Thioarsenical compounds determination was performed from solutions collected from sediment microcosms in anaerobic conditions that stimulate activity of sulfate-reducing bacteria with a transformation of sulfate to sulfide leading to a significant increase of dissolved arsenic. Speciation of As was performed by HPLC-ICP-MS according to the method of Wallschläger and Stadey (Anal. Chem. (2007), 79, 3873) allowing the determination of As(III), As(V) and four thioarsenate compounds (AsO3S3-, AsO2S23-, AsOS33- and AsS43-). After sample conditioning under nitrogen, stability of these compounds was studied at different temperature (-20°C, immediate freezing with liquid nitrogen followed by a storage at -20°C, +4°C and room temperature) and at different periods of time (24 hours, 1 week and 2 months) to optimize their analysis in routine conditions. Whatever the temperature, it appears that the time of storage particularly influences the As(III) concentration that decreases with time. The As(V) content remaining stable and the sulfide concentration high, a combination of As(III) with sulfides can be considered because AsO2S23- and AsS43- increase with time. However, it was shown that the most important factor influencing stability is the absence of oxygen and a sample conditioning under nitrogen preserves the samples for a few days, time required for sending samples. This study was part of ASEDMAR project, supported by the french National Research Agency under reference "2008 CESA-003".
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Communication dans un congrès
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https://hal-brgm.archives-ouvertes.fr/hal-00663197
Contributeur : Fabienne Battaglia-Brunet <>
Soumis le : jeudi 26 janvier 2012 - 13:07:21
Dernière modification le : vendredi 5 juin 2020 - 15:36:02

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  • HAL Id : hal-00663197, version 1

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Fabienne Battaglia-Brunet, Catherine Crouzet, Philippe Bataillard, F. Seby. Arsenic mobility in marine sediments: determination of thioarsenical compounds in porewaters. TRACESPES 2011, May 2011, Pau, France. ⟨hal-00663197⟩

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