Distinctive Features of the Formation and Migration of Radioactive Contamination in the Iput River after the Accident at the Chernobyl Nuclear Power Plant

With the example of the Iput river, studies are performed and based on them an analysis is made of the formation of contamination of elements of a river system by radionuclides 137 Cs and 90 Sr after the accident at the Chernobyl Nuclear Power Plant. It has been revealed that before the years 1990–1994 the contamination of the river system was mainly formed by the primary fallout of radionuclides on the water surface of the river but after the year 2000 it will be determined only by the ingress of radioactive contaminants with surface flow from a water catchment. The studies have shown that the contamination of the Iput river in the territory of Belarus is substantially influenced by the transfrontier transfer of radionuclides from the territory of Russia. According to our estimates, at the end of 1986, this contribution amounted to 30% for 137 Cs and 96% for 90 Sr; as of now, it is 86% and 65% for 137 Cs and 90 Sr, respectively.