Alexey Ivanovich Shcheglov

The article examines the levels of specific activity of man-made (137Cs) and natural (226Ra, 232Th, 40K) radionuclides in soils and biota components of the main ecosystems of the Teberdinsky National Park using the example of an ecological trail running along the Malaya Hatipara ridge (North Caucasus). Studies conducted in the conditions of a subalpine meadow (2600 m), pine (2300 m), fir (1700 m) and a meadow in the valley of the Teberdy river (1300 m) showed that all radiation characteristics — the power of the ambient equivalent dose of gamma radiation, specific activity and reserves of radionuclides in the soil and biota components are in within the normal limits. For natural radionuclides, they vary in the range: 226Ra — 14.71–24.95; 232Th — 20.95–29.25; 40K — 242.2–345.0 kBq.m-2. The density of soil pollution by 137Cs is 3.4 times lower than the indicator (37 kBq.m-2) established by the Law of the Russian Federation "On Social Protection of Citizens Exposed to the effects of radiation due to the Chernobyl disaster", and its presence in biota components in reliable quantities has not been recorded. However, the main radiation indicators are usually higher in the area of the subalpine meadow, located at an altitude of 2600 m.
In general, the radioecological situation on the ecological route of the Malaya Hatipara ridge is favorable, does not interfere with the development of ecotourism, therefore, the presence of people in this area is radiation safe.

The article examines the distribution features of one of the main radionuclides of the Chernobyl release — 137Cs — in the wood of the trunk of the Scots pine, depending on the age class. It is shown that in the long-term period after precipitation, the distribution of 137Cs in the stand of pine biogeocenoses in the territory of the Bryansk Polesie of the Russian Federation, which was most severely affected by the Chernobyl accident, at contamination  densities (2183 kBkm–2), exceeding the indicator established by the Law of the Russian Federation "On Social Protection of Citizens Exposed to radiation as a result of the Chernobyl disaster", and classifying the territories as radioactively contaminated (37 kBkm‒2), the minimum index (0,23 kBk kg‒1) and the average value of the specific activity of 137Cs in wood (2,24 23 kBkkg–1) does not exceed the standards for wood products for various purposes, with the exception of that for wood used for the construction of residential premises. The obtained novel data indicate that in the distribution of 137Cs, both by trunk height (from the top of the tree to the trunk) and by average indicators of wood contamination in general, there is a clear trend of a decrease in the specific activity of radionuclide depending on the age of the stand. In this regard, for the most adequate assessment of possible contamination of wood and compliance of the identified levels of specific activity of radionuclides with regulatory indicators, in particular in the context of construction use, sampling of this component should be carried out in relation to age groups in increments of 10 years.

Keywords: Bryanskoe Polesie, Chernobyl fallout, nuclear contamination, pine biogeocenoses, wood use, tree age class.