Identification of radionuclides' altitudinal distribution In soil and mosses In highlands of Armenia

Highlights: • K-40 and Cs-137 were investigated in mosses and soil in highlands of Armenia. • Characterization of K-40 and Cs-137 distribution by altitude were identified. • Dissimilar behaviour of K-40 and Cs-137 with different origin was confirmed. • The trend of decrease K-40 activity with the altitude identified for mosses. • Cs-137 activity increases in soil and moss and the altitude. The present study was conducted in mountain regions of Armenia with the aim to assess the activity concentrations of natural K-40 and artificial Cs-137 in soil and mosses and reveal the distribution similarities and differences. Most widespread moss species and surface soils were sampled concurrently from eight mountain ridges and massifs by different altitudinal belts. Statistical analysis revealed significant differences and opposite characteristics for K-40 and Cs-137. In case of K-40 the activity concentrations decreased in mosses by altitude but with no significant correlation. The mean activity concentrations of K-40 in the soils of different altitudinal belts are close, nevertheless, the higher activity concentrations are common for soils derived from ingenious rocks. For Cs-137 in mosses, the correlation with altitude is statistically insignificant, but the altitudinal dependence is noticeable within separate ridges and massifs. A significant correlation was identified between Cs-137 in soil, altitude and precipitation rate. Studying natural K-40 and artificial Cs-137 radionuclides together yielded interesting contrasting results confirming the dissimilar behaviour of radionuclides with different origins in the environment.