The anthropogenic fallout radionuclides in soils of Mount Khuko (the Western Caucasus) and their application for determination of sediment redistribution
2022
Ivanov, Maksim M. | Kuzmenkova, Natalia V. | Rozhkova, Alexandra K. | Grabenko, Evgeniy A. | Grachev, Alexei M. | Golosov, Valentin N.
The purposes of this study are to determine the content and origin of anthropogenic fallout radionuclides (FRN) in soils of Mount Khuko, located in the western sector of the Caucasus Mountains and to assess the possibility to use them for evaluation of sediment redistribution for the alpine grasslands,. The field study was carried out in August 2019 near the top of Mount Khuko, located in the western part of the main Caucasus Mountain Ridge. Integral and incremental soil samples were collected from the different morphological units of the studied area. The content of ¹³⁷Cs and ²⁴¹Am in soil samples was evaluated using laboratory gamma-spectrometry. A part of samples was selected for Pu isotopes extraction and then alpha-spectrometric analysis. It was established that the ¹³⁷Cs contamination of soils in the studied area has at least two sources of origin. The first source is the ¹³⁷Cs bomb-derived fallout after the bomb tests in 1950–60th, which is widespread across the globe. The second source is ¹³⁷Cs Chernobyl-derived fallout High random variability (Cv = 25–42%) was found within reference sites, located at the undisturbed areas on the local flat interfluves due to high variability of soil characteristics (grain size, density, organic matter content etc.). However minimum spatial variability (range 12,2–14,3 kBq/m²) was identified for the mean value of ¹³⁷Cs inventories for all 5 reference sites located in the different parts of the studied area. It is difficult to separate individual peaks of the bomb-derived and Chernobyl-derived ¹³⁷Cs falloutin sediment sinks with low sedimentation rates. Application ²³⁹,²⁴⁰Pu as an additional chronological marker allows to identify the origin of above mention peaks in the soils of alpine grasslands and of dry lake bottom.
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