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Couture, R. M., Universite du Quebec, Quebec, Canada, raoul.couture@ete.inrs.ca
Gobeil, C. ., Universite du Quebec, Quebec, Canada, charles.gobeil@ete.inrs.ca
Tessier, A. ., Universite du Quebec, Quebec, Canada, andre.tessier@ete.inrs.ca

LAKE SEDIMENTS AS ARCHIVES OF ATMOSPHERIC ARSENIC CONTAMINATION

Current emissions of arsenic (As) into the atmosphere are thought to globally increase as a result of human activities but temporal trends at regional scales are not well defined. We have determined the profiles of this redox-sensitive metalloid in dated (210Pb and 137Cs) sediment cores and in sediment porewater from Canadian Shield lakes, where atmospheric deposition is the only input of anthropogenic As. A one-dimensional transport-reaction equation was applied to the porewater As profiles in order to quantify the post-depositional addition or removal of As to the solid phase and estimate the sedimentary As concentrations at the time of deposition. By multiplying these concentrations by sediment mass accumulation rates, variations over the last two centuries in As fluxes at the sediment surface were estimated. The resulting chronological profiles in all lacustrines basins reveal that atmospheric As contamination was at its maximum in the 1950’s and significantly decreased since then; such a trend is consistent with the history of specific markers of coal combustion at the same sites.

Poster presentation

Session #:107
Date: 01-28-09
Time: 18:00 - 20:00

Presentation is given by student: Yes