干旱区生态环境知识资源中心

This study assesses changes in the environmental conditions in Chernyshov Bay (northern part of Aral Sea Western Basin) during the last similar to 2 ky from geochemical and diatom analyses of sediment core C2/2004. Comparison of fossil assemblages with the contemporary distribution of diatoms in the Aral Sea Suggests that considerable changes occurred in water level as well as salinity. Deposits with high diatom concentrations and dominance of the marine species Actinocyclus octonarius EHRENBERG are interpreted as periods of high water level, whereas replacement by Tryblionella compressa (BAILEY) BOYER is considered to indicate lake level fall. On the other hand sediments with low diatom concentration represent higher freshwater input and therefore salinity decrease. This interpretation is supported by estimates of siliciclastic and chemogenic sediment components. A chronology of major lake stages is derived and roughly agrees with recent findings from other studies.