Contribution to the external gamma dose rate from 137Cs and 40K activity concentrations determined along the vertical profile of sandy beaches

Abstract

Sampling sites, located along the Calabria and Basilicata Regions coastal beaches (south of Italy), were selected to assess the external gamma dose rate in air, 1 m above ground, and to estimate the fraction attributable to the radiocesium and radiopotassium contents along the vertical sand profile. Mean values for the gamma dose rate were: 76±30 nGy·h−1. 137Cs and 40K deposition densities in sand samples were determined for each sampling site (mean values 0.24±0.22 kBq·m−2 and 178±88 kBq·m−2, respectively). The 137Cs external dose rate contribution was assessed using a Monte Carlo simulation code. The method gives an estimation of the contribution to the external gamma dose rate of each sand layer along the vertical profile. The dose rate associated with the 137Cs content in sand was 0.16±0.14 nGy·h−1. The cosmic radiation and 40K contributions to the external gamma dose rate were estimated using the UNSCEAR methodologies. The values obtained were 34±3 nGy·h−1 and 18±9 nGy·h−1, respectively.