Natural radionuclides and oil products in river sediments and assessment of their impact on health in areas of intensive oil production (Timan-Pechora province of North–West Russia)
摘要
The present article is devoted to the study of the distribution of natural radionuclides (238U, 234U, 226Ra, 228Ra, 40 K, 210Pb) and oil products in river bottom sediments of the Pechora basin of the Timan-Pechora oil and gas province (north–west Russia). In addition, an analysis of radiological hazard indices for human health is also provided. The region's distinctive geology is characterised by a high concentration of oil and gas fields, the development of which has been linked to environmental concerns, including pollution. To date, the onshore part of the province has seen the discovery of over 268 hydrocarbon fields, of which more than 200 are oil fields. It is evident that the Kolva River (Komi Republic) is one of the most polluted rivers in the province. In order to identify the sources and regularities of radionuclide accumulation in bottom sediments, the total alpha- and beta-radiation activities, the content of organic matter and carbonates, as well as the granulometric composition of sediments were additionally evaluated. The study revealed that the highest activities of natural radionuclides are observed in the bottom sediments of the Kolva River. The activity of 226Ra in the bottom sediments of the Kolva River at certain points has been found to reach 89.0 ± 7.1 Bq kg–1. This is generally higher than the activity levels recorded in the bottom sediments of rivers in North-West Russia. Correlation analysis and calculation of 226Ra/228Ra and 226Ra/210Pb isotope ratios demonstrated that relatively high values of 226Ra activity in the bottom sediments of the Kolva River can be associated with oil and gas activity in the region. The following factors are of particular significance in this regard: the low (at the background level) uranium isotope content in bottom sediments, the increased content of oil products (up to 101.2 mg kg−1), and the very close correlation of 226Ra with the content of oil products in bottom sediments (R = 0.74). It is important to note that the elevated 226Ra activities detected in the sediments of the Kolva River may have a significant impact on the radioactive composition of the sediments of the Pechora River. Slightly elevated 226Ra activities have been detected in some samples from the Pechora River when compared to clark values and other rivers in the region. The identification of zones exhibiting elevated concentrations of natural radionuclides in the bottom sediments of the Pechora basin has informed an assessment of their radiation safety parameters, with particular regard to their potential impact on human health. The findings of the study indicated that the radioecological situation within the Pechora basin remains stable and at a safe level at present. However, the authors note the necessity of periodic radioecological monitoring on the territory of the Timan-Pechora province for the timely detection of contamination of environmental objects with natural radionuclides.