FATE OF SOME CHLORINATED HYDROCARBONS IN ARCTIC AND FAR-EASTERN ECOSYSTEMS IN THE RUSSIAN-FEDERATION

Since the 1970s, the Russian Federation has been carrying out a broad-based study of chlorinated hydrocarbons in the environment. As part of this study, a joint USSR/US investigation was begun in 1984 in the Bering and Chukchi Seas to investigate the transport of agricultural chemicals such as pesticides and other persistent pollutants. Since the impact of chlorinated hydrocarbons on the coastal environments of Russia has changed since the mid-1980s, forecasts of the behavior of these chemicals in the far eastern and arctic marine areas require clarification. Results from two integrated expeditions and several local investigations between 1988 and 1992 to far eastern and polar Russian seas demonstrated that during the last 5 years, the composition of chlorinated hydrocarbons in surface waters has shifted towards larger amounts of alpha-HCH and smaller amounts of highly chlorinated PCB congeners. Significant decreases in PCB concentrations (from 100-900 pg/l to 12-20 pg/l) were observed from 1988 to 1992 in the seas surrounded by far eastern countries. alpha-HCH concentrations increased from 800 pg/l in the South China Sea to 2500 pg/l in the Chukchi Sea. This trend in alpha-HCH concentration has been seen by other researchers and may reflect the effect of much colder surface water temperatures in the polar seas. The Henry's law constant of alpha-HCH decreases with decreasing water temperature, thus favoring deposition to the water phase. Higher than expected gamma-HCH levels were found near the coasts of Russia and Japan, indicating local sources. Composition of other chlorinated hydrocarbons (DDTs and chlordanes) has not changed considerably during the last 5 years. No significant changes in concentrations of global chlorinated hydrocarbons, including HCHs, were observed in the seas of the western part of the Russian Arctic, where usage patterns have not changed significantly.