Transformation of the radionuclides composition of river sediments in the area of the exploited Lomonosov diamond deposit (NW Russia)

The article is devoted to the study of the activity of the natural radionuclides K-40, Th-232, Ra-226 and technogenic Cs-137 radionuclide in the river sediments of watercourses around the Lomonosov diamond deposit (northwestern Russia). This is the only large diamond mining and beneficiation complex in Europe. Samples of river sediments and surface waters were taken from the Zolotitsa River and its tributaries in the area of the diamond deposit. Samples of rocks were taken from quarries. Samples of kimberlites used for enrichment and rocks entering the dumps were selected. Measurements of the activity of radionuclides in bottom sediments and rocks were conducted using the low-background semiconductor gamma spectrometry method. For measurements, a detector from high-purity germanium was used. The study of uranium isotopes in bottom sediments and waters was conducted using the alpha spectrometry method. The average activity of Cs-137, Ra-226, Th-232 and K-40 were 5.4, 9.0, 11.2, 318.8 Bq.kg(-1) respectively. The impact of the development of the field on the change in the radioecological state of the bottom sediments was evaluated. Several patterns of radionuclide accumulation have been found depending on the physicochemical parameters of river sediments. These patterns are due to the technogenic influence of the mining and beneficiation complex. The performed studies present the first evaluation of the impact of diamond mining on natural radionuclides' distribution and accumulation in the river sediments within the adjacent territories.