Characterization of Lake Ladoga sediments. II. Toxic chemicals

Chemical contamination of Lake Ladoga was studied by analyzing 12 sediment samples collected at various parts of the lake for polyaromatic hydrocarbons, chlorobenzenes, organochloropesticides and heavy metals. The results were also used to explain the negative effects of these sediments observed earlier in bioassays with a midge Chironomus riparius (Ristola et al. 1995). Concentrations of analyzed chemicals were mostly typical to lakes which are considered as unpolluted. Only the concentrations of PAH were somewhat elevated in the sediment collected near River Volkhov inlet in the southern part of the lake. Adverse effects on midges could, however, not be explained by chemical contamination.