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Sediment samples were collected in May 1995 from 16 locations in Kola Bay, North-west Russia, during an expedition starting from Murmansk and ending at Kildin Island in the Barents Sea. The purpose was to study the contamination level in an area with several potential sources of civilian and military radioactive pollution. 137 Cs concentrations in the sediments, algae and benthic samples were low, but small particles containing 137 Cs were separated from the sediment samples. All the sediments between the nuclear icebreaker base Atomflot and the open Barents Sea contained 60 Co. Traces of 125 Sb, 134 Cs, 95 Zr, 154 Eu and 152 Eu were also detected in some of the samples. Plutonium levels were low, but the increased 238 Pu/ 239,240 Pu ratio at Atomflot indicated a fresh release from the facility or from the waste storage vessels, Lepse and Imandra, lying in front of it. An increased 238 Pu/ 239,240 Pu ratio was also found in sediment collected in the outlet of Kola Bay in the Barents Sea.

This work contributed to a joint research programme between the Finnish Centre for Radiation and Nuclear Safety and the Murmansk Marine Biological Institute in the Arctic. Radioanalyses for plutonium isotopes were performed on more than 50 sediment samples, 12 algae samples and 19 fish samples. Plutonium concentrations in algae and fish samples, including fish meat, bone and liver, were low or in many cases below detection limits. Some differences in plutonium concentrations of sediments were found between different sampling areas. However, the concentrations were low. The Pu isotopic ratios were similar to those found in environmental samples generally when Pu is derived from global fallout or discharges from reprocessing plants. No local enhancement of plutonium contamination was found in the marine areas studied. However, the sampling locations represent only areas of free access; prohibited military areas of North-west Russia with potential pollution sources were not included.