The 'Karex - Pechora' expedition marine investigations by the research vessel 'Ivan Petrov' in the Kara and Pechora seas in August 2000, and by the research vessel 'Hydrolog' during September-October 2000. During August 2000 samples of marine water, suspended and bottom sediments at 30 oceanographic stations were analyses for contaminants. At 8 stations, hydrobiological investigations included sampling of benthic organisms, plankton and fish, for studies of bioaccumulation and transformation of contaminants.