Specific activity and features of vertical migration of strontium-90 in the peat bog of the Murmansk region

The peatlands of the Arctic territories are repositories of radioactive contaminations. The physicochemical properties, specific activity and features of vertical migration of 90Sr in the peat profile of the Murmansk region have been studied. A correlation matrix was compiled according to the studied indicators. The factor that determines the localization of 90Sr in peat has been established. The sources of isotope for the region were determined. The reaction of the peat medium is acidic (4.2 ≤ pHwater ≤ 4.9; 3.6 ≤ pHsalt ≤ 4.1). The ash content of peat is medium and high (5.2 % ≤ Ash ≤ 28 %). The share of organic matter in the peat profile is more than 70 %. The upper part of the profile is saline (soluble salts>0.3%). The share of carbonates in the peat profile is insignificant (0.42-0.83 %). 90Sr activity (0.55-7.7 Bq/kg) was recorded in each peat sample. The activity of the technogenic radionuclide is below the established permissible norm and within the range typical for all Russian soils. The 90Sr isotope is localized in the upper layers of the profile and at a depth of more than 16 cm. The localization of 90Sr in peat layers is due to the content of water-soluble salts (r = 0.85). The main sources of the isotope for the Murmansk region are past global fallout from nuclear tests, the Chernobyl accident and current local fallout from nuclear fuel facilities.