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 Be ring and Chukchi Seas to investigate the transport of agricultural che micals such as pesticides and other persistent pollutants. Since the i mpact of chlorinated hydrocarbons on the coastal environments of Russi a has changed since the mid-1980s, forecasts of the behavior of these chemicals in the far eastern and arctic marine areas require clarifica tion. Results from two integrated expeditions and several local invest igations between 1988 and 1992 to far eastern and polar Russian seas d emonstrated that during the last 5 years, the composition of chlorinat ed hydrocarbons in surface waters has shifted towards larger amounts o f alpha-HCH and smaller amounts of highly chlorinated PCB congeners. S ignificant 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 e astern 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 alp ha-HCH concentration has been seen by other researchers and may reflec t the effect of much colder surface water temperatures in the polar se as. The Henry's law constant of alpha-HCH decreases with decreasing wa ter temperature, thus favoring deposition to the water phase. Higher t han expected gamma-HCH levels were found near the coasts of Russia and Japan, indicating local sources. Composition of other chlorinated hyd rocarbons (DDTs and chlordanes) has not changed considerably during th e last 5 years. No significant changes in concentrations of global chl orinated hydrocarbons, including HCHs, were observed in the seas of th e western part of the Russian Arctic, where usage patterns have not ch anged significantly.