For proper management of soil and groundwater quality, background levels of toxic elements in a given ecosystem must be known. The aim of this study is to determine quality reference values for radioactive content in representative soils from the São Paulo State, Brazil. Thirty samples were collected and the concentration of U-nat, Th-nat, 228Ra, 226Ra, 210Pb, 137Cs and 40K were evaluated and correlated with soil mineralogical characteristics. The types of soil and sampling places were chosen according to their representativeness and spatial distribution in the State geological formations, taking also into account their nearness to large urban areas. The samples were measured by means of passive gamma spectrometry and sequential chemical extraction, followed by alpha spectrometry. Results showed a wide variation on background levels for natural radionuclides of the uranium and thorium series and very low concentration of 137Cs from radioactive fallout.
Hiromoto, Goro; Peres, Ana Claudia; Tadei, Maria Helena; Soares, Marcio Roberto; and Alleoni, Luis Reynaldo Ferracciu
"Radioactive Soil Characterization Of The State Of Sao Paulo, Brazil,"
Proceedings of the Annual International Conference on Soils, Sediments, Water and Energy:
Vol. 12, Article 19.
Available at: http://scholarworks.umass.edu/soilsproceedings/vol12/iss1/19