Accumulation of natural radionuclides (7Be, 210Pb) and micro-elements in mosses, lichens and cedar and larch needles in the Arctic Western Siberia

This is a study of the atmospheric-origin natural radionuclides ( 7 Be and 210 Pb) and a wide range of micro- and macro-element accumulation in mosses, lichens, cedar and larch needles in Arctic western Siberia (Yamal-Nenets Autonomous District). Based on the specific activities measurements of atmospheric precipitation markers ( 7 Be and 210 Pb), this study found that the concentration of dust particles in the studied objects incrementally increases in the following order, from lowest concentration to highest: cedar needles, larch needles, lichens and mosses. Concentrations of Zr, Hf, Ti, Th, Fe, V, Li, Na, Si, Be, Y, rare earth elements (REE) and Sc in this area also increase in the same ascending sequence. Enrichment factors of these elements (EF) relative to the North American Shale Composite (NASC) are close to unity, which proves their terrigenous origin. Also, the terrigenous origin of the elements in the studied biological objects is confirmed by their high correlation coefficients with Sc. This means that their concentration in the studied biological objects is the result of a background of solid atmospheric precipitation. Enrichment factors of biogenic elements and their analogues (P, Se, Mn, Mg, Ca, K, Zn, Sr, Ba, Rb, Cs) are significantly greater than unity, and this is associated with high concentrations of these elements in the biological part of the samples. A radially symmetric distribution of Pb content in biological objects is observed over the surface of the studied area (with a center located within the city of Novy Urengoy). This leads to the conclusion that there is a point source around which anthropogenic precipitation of Pb takes place. This distribution is most clearly manifested by the example of larch and cedar needles. Anthropogenic deposition of other elements has not been detected in this study area.