The rates of accumulation and chronologies of atmospherically derived pollutants in Arctic Alaska, USA

Anthropogenically derived pollutants (e.g. trace metals, organochlorines, radionuclides) are deposited upon arctic ecosystems. To determine the range of probable biotic effects of these pollutants, one must know the rate at which they enter and are retained within an ecosystem. However, unknown deposition mechanisms and the complexity of quantifying atmospheric concentrations of constituents of interest make direct measurements of pollutant flux to arctic terrestrial and aquatic ecosystems difficult and/or impractical. Methods of indirectly measuring rates of pollutant accumulation, such as lake sediment stratigraphic analyses, can fill this void. Present in the sediment of two Alaskan lakes sampled in April 1991 were quantifiable concentrations of numerous organochlorine compounds, including DDT and its metabolites (Sum, 0.05-0.60 ng/g), PCBs (Sum, 0.20–30 ng/g), and lindane (0.20-0.80 ng/g). These surface concentrations correspond to estimated deposition rates of 2–6 ng/m2/year ( ∑DDT + metabolites), 10–300 ng/m2/year ( ∑PCBs), and 8–10 ng/m2/year (lindane). The rates and chronologies of accumulation of these pollutants and others are discussed with regard to the process of long-range atmospheric transport.