Radioactive elements in atmospheric precipitations of the Western Siberia

Abstract

The radionuclide composition of the atmospheric precipitations (rain and snow) fell out on the territory of the South of the Western Siberia in 2016-2017 was studied. It is shown that, the maximum of deposition of 7Be and 210Pb were observed in a foothill zone (618 and 171 Bq/m2), the minimum in the Alpine zone (104 and 27 Bq/m2), for the forest-steppe zone these values are 237-340 Bq/m2 and 73-93 Bq/m2. Deposition density of 137Cs in comparison with 210Pb and 7Be is small and does not exceed 1 Bq/m2. Average values of total specific activities of 210Pb and 7Be in rain waters are 242 and 2434 mBq/l, in the snowmelt 506 and 1611 mBq/l. 7Be/210Pb activity ratio in rain waters more than three times higher, than in snowmelt: 10,1 to 3,2. The highest values of 7Be/210Pb activity ratios are observed in the finest fraction (<0.45 µm) of the suspended matter: 19 in rain and 10 in snowmelt waters.

Natural and Manmade (137Cs) Radioisotopes In Holocene Sequnce of The Sheresrtobitovsky Raised Bog In The Barabinsk Forest Steppe (West Siberia)

“…The important value characterizing the source of radioisotope intake on the Earth's surface is the 7 Be/ 210 Pb atm ratio (Melgunov et al, 2019a). The data presented in Table 1 demonstrate that very close values of 7Be/ 210 Pb atm ratios: from 0.71 to 0.74 with an average of 0.73 for the Sherstobitovsky raised bog and 0.66-0.85 (average of 0.74) for the Ubinsky burnt raised bog.…”

“…One of the main migration roads of natural radioisotopes ( 7 Be, 210 Pb,226 Ra, 232 Th, 238 U, and 40 K) and manmade radionuclide 137 Cs is an atmospheric transportation. Radioactive elements transferred by air enter to Earth's surface among dry (dust, aerosol) and "wet" (rain, snow) atmospheric fallouts (Lal at al., 1958;Melgunov et al, 2012Melgunov et al, , 2019a. In recent studies, "atmospheric" radioisotopes 7 Be and 210 Pb are often used as indicators of atmospheric transportation processes in the composition of aerosol and dusty particles.…”

“…210 Pb (T 1/2 =22.3 years) is the decay product of 222 Rn, which, in turn, is formed as a decay result of radionuclides of the 238 U radioactive series entering the atmosphere from the Earth's surface. Nearly formed 7 Be and 222 Rn atoms and their decay products are electrically charged and almost immediately after their appearance, these are captured by aerosol and dust particles and all of them fall on the Earth's surface (Melgunov et al, 2019a). Manmade radionuclide 137 Сs (T 1/2 =30.1 year) enters the atmosphere as a result of nuclear weapon tests and accidents at nuclear power plants (Gauhier-Lafaye et al, 2008;Linnik, 2018;Melgunov et al, 2012;Rhikvanov, 2009;Sapozhnikov et al, 2006).…”

“…The snow cover is an excellent surveying plane table accumulating information about atmospheric inputs of radioisotopes over a su ciently long time interval from the rst snowfall during the late autumn period to its melting in spring. It can be successfully used for assessment of the deposition density of a number of radioisotopes, including 7 Be and 210 Pb (Mezina and Melgunov, 2019;Melgunov et al, 2019a).…”

7 Be, 210Pb AND 137Cs IN ATMOSPHERIC deposition OF SOUTHERN AND ARCTIC REGIONS OF WESTERN SIBERIA

“…Previous studies [17] allowed us to obtain a preliminary estimate of the amount of 7 Be, 210 Pb and 137 Cs entering the Earth's surface as a part of snowfall in the southern regions of Western Siberia. In fresh snow specific activities of 210 Pb and 7 Be precipitated and sampled on this territory in the 2016-2017 winter period were 506±45 and 1611±130 mBq L -1 , calculated to snow waters.…”