Aquatic Sciences Meeting, Albuquerque 2001

SS08 Processes at the Benthic Interface (Environmental Connections)

Date: Monday, February 12, 2001, Time: 3:45:00 PM

Location: Ruidoso/Pecos

Lucotte, M, , GEOTOP - Université du Québec à Montréal, Montréal, Canada, lucotte.marc_michel@uqam.ca

Kainz, M, , GEOTOP - Université du Québec à Montréal, Montreal, Canada, c3005@er.uqam.ca

Parrish, C, C, OSC - Memorial University of Newfoundland, St. John's, Canada, cparrish@mun.ca

IDENTIFICATION AND DEGRADATION OF ORGANIC MATTER AND ITS IMPORTANCE FOR METHYLMERCURY CONCENTRATIONS IN LACUSTRINE SEDIMENTS

Methylmercury (MeHg) is a powerful neurotoxin which accumulates in fish and can consequently harm human health. MeHg rich organic matter at the sediment-water interface may be mobilized to the water column and hence made bioavailable to lake biota. In this study, we examined the nature of sedimentary organic matter at the sediment-water interface (0-5 cm) and its implications for bacterial production of MeHg. Sediment cores were taken from littoral and pelagic sites of Lake Lusignan, Québec. The highest MeHg concentrations have been found at the uppermost sediment layers which are four times more contaminated at littoral than pelagic sites. Analyses of fatty acid biomarkers reveal that allochthonous organic matter is twice as high in littoral sediments. However, both bacterial and algal biomass is twice and three times higher at the littoral than at the pelagic sediment-water interfaces, respectively. These results indicate that the higher microbial abundance in littoral sediments is likely to favor higher MeHg production. Our detailed analyses of surficial sedimentary lipids suggest that fatty acid biomarkers are valuable source indicators for the lipophilic MeHg.

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Aquatic Sciences Meeting, Albuquerque 2001

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