Information on radiation safety of aquatic biological resources of the Far Eastern Fishery Basin
In 2015, research vessels of FSBSI TINRO-Center (Federal State Budgetary Scientific Institution Pacific Research Fisheries Center) organized 7 expeditions to conduct annual observations of the radiological environment in the fishing grounds of the Far Eastern Fishery Basin.
The radiological environment was monitored by way of daily shipboard dosimeter measurements of the background radiation level of air, water and catches with professional dosimeters MKS-01SA1M, MKS-05 Terra, DKG-RM1203M, and by sample collection of aquatic biological resources and sea water samples for the subsequent tests for radioactive isotopes cesium-137 and strontium-90 in TINRO-Center laboratory using radiochemical methods and spectrometric instruments.
For the period from March to November 2015, TINRO specialists made over 6,500 measurements of the background radiation level of air, water and catches. Integration and analysis of the received data showed that in the waters of Russia’s Exclusive Economic Zone and in the northwestern part of the Pacific Ocean the background radiation was 5-12 micro Roentgen per hour, i.e. within normal limits.
TINRO specialists tested the main types of commercial fish of the Far Eastern Basin for contents of man-made radioactive isotopes cesium-137 and strontium-90:
- in the Sea of Japan – flounder, pollock, greenling;
- in the Sea of Okhotsk – pollock, herring;
- in the Bering Sea – pollock;
- in the northwestern part of the Pacific Ocean – pink salmon.
Due to various factors, artificial radioactive isotopes of the global origin, including Cs-137 and Sr-90, are present in any living organism of the planet creating the background radiation.
The data received from the radionuclide tests of fish samples proved that the contents of cesium-137 and strontium-90 were with certainty similar in different fish type selections made in the Far East seas and in the northwestern part of the Pacific Ocean. The specific activity of Cs-137 was between 0.4 and 1.2 Bq/kg and of Sr-90 – between 0.6 and 1.0 Bq/kg of raw fish weight, which is significantly lower than the permissible levels of radioactive isotopes cesium-137 and strontium-90 established by the sanitary norms of the Russian Federation (130 and 100 Bq/kg correspondingly). The revealed contents of toxic radioactive isotopes fully comply with the Unified Sanitary, Epidemiological and Hygienic Requirements approved by the Customs Union Commission decision No. 299 on 28 May, 2010.
Special attention during radiation environment evaluation was given to pollock, as it is one of the numerous aquatic biological resources in Russia’s Far East seas.
The weight and size of pollock in commercial catches vary significantly depending on the fishery area and season, as well as on the age and sex composition of aggregations being fished. Tested samples of pollock from the Sea of Japan and the Sea of Okhotsk were small-sized with Cs-137 contents being 0.42 and 0.56 Bq/kg correspondingly. Pollock from the Bering Sea was larger (1.0 – 1.2 kg) and the specific activity of Sc-137 was 0.83 Bq/kg of wet weight. These values are more than 150 times lower than the established limit.
The data received by the Russian researchers from TINRO-center are supported by the results of the research conducted by Korean scientists from Radiation Monitoring Center of the Institute for Environment & Community Development Studies. The recently published article referencing the institute research stated that the contents of radioactive cesium in some samples of pollock and cod being of Russian origin were registered in values of 0.37 and 1.09 Bq/kg correspondingly. The contents of radioactive isotope Cs-137 revealed by Korean specialists in the samples of pollock are lower by a factor of 100 (for more than 100 times) than the levels permitted by the sanitary norms of the Republic of Korea (100 Bq/kg).
The results of the radioecological investigation conducted by TINRO-Center in 2015 proved that the accident in Fukushima Daiichi nuclear power station that occurred in Japan in 2011 had no negative effect on the background radiation in Russia’ fishing grounds. All values of artificial radioactive isotope concentration in the aquatic biological resources and in their habitat correspond to the pre-accident level and are absolutely safe for man.
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