Mapping of the concentration of natural radionuclides in the Fundão Island, RJ, Brazil supported by geoprocessing and IDW interpolation

This work aims to determine the concentration activities of 226 Ra, 228 Ra and 40 K radionuclides in soil samples from Fundão Island, Rio de Janeiro, using the gamma spectrometry technique with a hyper-pure germanium detector. The concentration found for 226 Ra in the evaluated soil samples showed an average 42.21 Bq kg −1 , a value within ranges found in national and international studies. For concentrations of 228 Ra, the average found were around 131.23 Bq kg −1 , being higher than the values found for soils in national and international studies. The 40 K presented average values around 543.35 Bq kg −1 , therefore within the range found for soils in both national and international literature. Amongst the analyzed samples and the determined elements, the 228 Ra was the highest concentration detected. This result suggests that in these soils, the forming minerals are more concentrated in 232 Th.