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Communication dans un congrès

Bacterial activities driving arsenic speciation and solubility in marine sediments

Abstract : High concentrations in organic carbon and pollutants are found in harbor and marina sediments. Over 50 million m3 of marine sediments are dredged every year in French maritime and commercial ports, the most part of them being discharged in deeper sea zones. High concentrations of arsenic in marine sediments of the South Marseille littoral (France) and excess of carcinogenic effect level through mussel consumption have recently been reported. If the marine cycle of arsenic is well described in the water column, only scarce data are available on the phenomena controlling arsenic transport from sediment to water column. The aim of the present work was to evaluate the influence of microbial processes on the mobility and ecotoxicity level in polluted sediment marina (L'Estaque) impacted by metallurgical activities and by the commercial port of Marseille. Arsenic concentration was noticeably high (200-350 mg/kg), arsenite (AsIII) being the dominant form, and arsenic was the major trace element detected in interstitial water. Biotic phenomena linked to arsenic mobility were compared in dark aerobic and anaerobic microcosms. Sulfate reduction was favored in dark anaerobic microcosms and induced a dramatic increase of arsenic concentration in the liquid phase, linked to the formation of soluble thio-arsenic complexes also detected in the interstitial water, whereas the bacterial activities in aerobic microcosms resulted in a decrease in arsenic transfer from the sediment to the overlying water. Aerobic light microcosms were used to simulate the exposure to natural light of the sediment surface. Here, a clearly distinct, oxidized, red-brown fine layer appeared at the sediment/water interface. The diversity of aoxB genes involved in the bio-oxidation of AsIII to the less mobile AsV (arsenate) was high and similar in the oxidized layer and the deeper black-colored sediment. Such results gave new insights on bacterial AsIII oxidation, which is to date only poorly studied in marine environments. Altogether, the results suggest that aerobic microbial processes reduce the transfer of arsenic from the sediment to the water column. Biogeochemical reactions governing its mobility, including direct ones such as oxidation of AsIII as well as indirect ones such as sulfate reduction, should thus be considered in the management of sediment dredging operations.
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Communication dans un congrès
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https://hal-brgm.archives-ouvertes.fr/hal-00710150
Contributeur : Catherine Joulian <>
Soumis le : mercredi 20 juin 2012 - 10:47:45
Dernière modification le : mardi 21 avril 2020 - 11:56:06

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  • HAL Id : hal-00710150, version 1

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Fabienne Battaglia-Brunet, Fabienne Seby, Catherine Crouzet, Catherine Joulian. Bacterial activities driving arsenic speciation and solubility in marine sediments. 14th International Symposium on Microbial Ecology (ISME14), Aug 2012, Copenhague, Denmark. ⟨hal-00710150⟩

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