Anthropogenic radionuclides in Peter the Great bay

A comprehensive investigation of radionuclide distributions in seawater and bottom sediments of Peter the Great bay was conducted in September–October 1994. Sampling sites were chosen close to potential radioactivity sources as well as in fishing and recreational areas. The results have shown that the main sources of radionuclides in Peter the Great bay are still global atmospheric fallout and the discharge of freshwater and suspended sediments from river runoff. Activities of 137Cs and 90Sr in seawater were in the ranges 1.7–5.7 and 1.7–6.6 Bq m−3, respectively, with activities of 137Cs in bottom sediments <1.1–22.9 Bq kg−1 (dry weight). As a result of the accident with a nuclear submarine reactor in 1985, 60Co was found in bottom sediments of Strelok bay (close to Chazhma bay entrance, up to 150 Bq kg−1) and in a limited area in Ussuriysky bay (up to 21.6 Bq kg−1). Further studies in 1996 and 1997 also did not reveal any radionuclide sources connected with the navy facilities except for the consequences of the Chazhma bay accident.