Natural radionuclide levels and the associated radiological risks in soils from the three mesoregions of Pernambuco state, Brazil

A large-scale survey of natural radionuclides in the soils is presented. 105 topsoil samples were collected and analysed by gamma spectrometry. The data indicated that climatic conditions might impact the content of natural radionuclides. Low-humidity conditions and igneous bedrock were associated with the highest median value of ⁴⁰K in the Agreste region (667 Bq kg^-1). The humid climate of Zona da Mata was associated with the lowest median value of ⁴⁰K (39 Bq kg^-1) and the highest levels of radium. Soils from most parts of the state may be used as building materials without presenting a radiological risk. (author)