Study of distribution of radionuclides in cultivated land in and around chikmagalur, Karnataka, India

Abstract

Cultivation of land modifies soil characteristics and influences redistribution of radionuclides in topsoil. The concentrations of 210 Po and 210 Pb in the cultivated land of Chikmagalur were measured by wet ashing silver planchet electroplating alpha count method. The concentration of 226 Ra was determined using Emanometry Method. The samples were precipitated by chemical processes and the concentrations of 228 Ra measured using high efficiency low level background gas flow beta counter. The lowest activity of 226 Ra, 228 Ra 210 Po and 210 Pb recorded at study area were 6.1, 5.6, 12.9 and 20.6 Bq.Kg -1 and maxima were 47.7, 29.6, 71.2 and 120.5 Bq.Kg -1 and mean 13.8, 19.2, 28.6 and 1.8 Bq.Kg -1 respectively. The mean of ratios of 210 Po and 210 Pb in cultivated and uncultivated land were found to be 0.53 and 1.06 respectively. Concentrations of 226 Ra, 228 Ra and 210 Po in cultivated land found to be lower than that of undisturbed land but reverse in case of 210 Pb. Decrease in activities of 226 Ra, 228 Ra, and 210 Po in cultivated may due to wash out of 'floating fraction' with rainwater and the increase of activity of 210 Pb may be due to re-suspension. The 're-suspension factor' (K) increases for 226 Ra, 228 Ra, and 210 Po in cultivated and fertilizer added area, but not for 210 Pb. Also the concentrations of radionuclides were found to be high in comparison with global and Indian average.