Main tendencies in distribution of major natural and technogenic radionuclides in the bottom sediments from the eastern part of the Gulf of Finland
In this paper, based on the results of analytical data processing and methods of mathematical statistics the authors show that: 1) facies conditions exert a significant influence on the conditions of migration and distribution of radionuclides in bottom sediments of the Gulf of Finland, 2) the main factor affecting the characteristics of accumulation of <sup>137</sup>Cs, <sup>40</sup>K, and <sup>232</sup>Th in bottom sediments of the Gulf of Finland is their lithological composition, 3) in deposits of areas with weak accumulation of sediment, radiocesium is mainly accumulated due to its sorption immediately from the bottom water, and in sediments of sedimentary basins - mainly in clay sediments that adsorbed radiocesium on the ground, and then were washed out in the waters of the Gulf, 4) the main factor affecting the characteristics of <sup>226</sup>Ra accumulation in bottom sediments of the Gulf of Finland is mainly the presence of alkali and sorption geochemical barrier at the water-bottom interface.