Assessment of trace metals contamination in sediments of Kossou Lake (Côte d’Ivoire).

Abstract

This study was conducted to evaluate the pollution level of some trace metals (Pb, Cd and Hg) in the surface sediments of Kossou Lake in Côte d'Ivoire. Two sampling campaigns, one in the rainy season and the other in the dry season, were carried out at five sampling stations. In rainy season, the average concentrations (in mg/kg dry weight) are 52.76 for Pb, 0.59 for Cd and 0.03 for Hg. In dry season, they are 92.75 for Pb, 1.17 for Cd, and 0.02 for Hg. Our results generally show that the accumulation capacity of the trace metals varies according to the sampling site and the season. The comparison of our data with freshwater sediment quality standards shows that the studied sediments are contaminated by Pb and Cd during both seasons. This result is confirmed by the geoaccumulation index (Igeo) which generally indicate moderate contamination of sediments by Pb and Cd, as well as an absence of Hg contamination.