Soil depth profiles and radiological assessment of natural radionuclides in forest ecosystem

Abstract We measured the distribution of three naturally occurring radionuclides, 238U, 232Th, and 40K, in soil samples collected from a rainforest in the Western Ghats of India. For each surface sample, we calculated average activity concentration, outdoor terrestrial γ dose rate, annual effective dose equivalent (AEDE), and radiation hazard index. The activity concentrations of surface samples were randomly distributed over space, but differed slightly with different soil depths. The concentration of 232Th and the average terrestrial γ dose rates were slightly higher than the world averages, so slightly high γ radiation appears to be a general characteristic of the Western Ghats. However, all radiological hazard indices were within the limits proposed by the International Commission on Radiological Protection. The results reported here indicate that, except for 232Th, the naturally occurring radionuclides in the forest soils of the Western Ghats were within the ranges specified by United Nations Scientific Committee on the Effects of Atomic Radiation for undisturbed virgin soils.