This work evaluated the activity concentration of radionuclides on sedimentary and igneous rocks at Corumbataí river basin, São Paulo State, and, consequently, the exposure rate. This basin possess a large sugar cane crops area, where occurs the application of phosphate fertilizers, and where is located the most important ceramic center of South America (Santa Gertrudes Ceramic Center). The chemical characterization of the samples indicated that Ca > Mg > K > Na, which is related to the mineralogy of each formation. The weighted mean exposure rate (35 nGyh-1) to the studied formations represent just 64% of the world average due to terrestrial gamma radiation, occurring the highest exposure rate at the south-east portion of the area. The data obtained can be utilized in environmental studies involving the basin, including those related to the land use.
Radioactivity; Gamma exposure rate; Watershed
