Abstract

  The pollution level of some organochlorine pesticides and polychlorinated biphenyls in snow and surface waters of all main altitudinal belts of the mountains surrounding Lake Baikal was estimated for the first time.
  The southern part of the Baikal region was more polluted by hexachlorocyclohexanes (consisting of the pesticide lindane and the isomer a-hexachlorocyclohexane and polychlorinated biphenyls) than the northern part, pointing out the role of atmospheric pollution sources, located mainly to the west of Lake Baikal. Dichlorodiphenyltrichloroethane (sum of the isomers) contents in snow did not show spatial differences and varied little with altitude. In the Baikal region this pesticide is apparently mainly of global origin.
  The organochlorine contamination of surface waters of the Lake Baikal catchment area showed great spatial and temporal variation& Organochlorine pesticides were observed in the main tributaries of Lake Baikal throughout the year.
  Dichlorodiphenyltrichloroethane balance showed that this substance in soil exceeds by dozens of times its atmospheric deposition, which proves the great resistance of the pesticide to breakdown in the Baikal environment and indicates the large volume of its deposition in previous years. © 2000 Published by Elsevier Science Ltd.

Keywords: Lake; Drainage basin; Pollution