Spatial Distribution and Qualitative Composition of Polychlorinated Biphenyls and Organochlorine Pesticides in Bottom Sediments and Bream (Abramis brama L.) from the Rybinsk Reservoir

摘要

Persistent organic pollutants (POPs) were found in bottom sediments and muscles of a freshwater fish, bream (Abramis brama L.), from the Rybinsk Reservoir. The contents of POPs decreased in the following order: PCBs > DDT > HCH > HCB. The POPs contents vary within the ranges of 0.14-50.8,1.8-6.8,0.64-2.6, and 0.06-0.41 μg/kg wet weight for fish and 24.8-425.6, 2.3-27.1, and 0.34-0.83 μg/kg dry weight for bottom sediments (except for HCH), respectively. The highest and lowest POPs levels were found in the Sheksna and the Mologa reaches of the reservoir, respectively. The differences in the spatial distribution of POPs in the reservoir relate to the ways that contaminants enter and migrate in the waterbody but not to various compositions of bottom sediments. The waste waters of the city of Cherepovets are the main local source of POPs in the Sheksna reach of the reservoir; in the Mologa reach, the contaminants enter with surface runoff and through global transboundary and local atmospheric transports from the Cherepovets industry. The qualitative composition of POPs evidences their continuing income to the reservoir. Considering the revealed levels of POPs accumulation and their legislative safe environment levels, it should be concluded that PCBs represent the highest environmental threat to the reservoir's ecosystem.