Determination of REE and U in agricultural soils from Jaguari River basin, Sao Paulo, by neutron activation analysis

Uranium has the highest atomic weight of the naturally occurring elements. It is weakly radioactive and occurs naturally in low concentrations (a few parts per million) in soil, rock and water. The rare earth elements (REE) form the largest chemically coherent group in the periodic table. The versatility and specificity of the REE have given them a level of technological, environmental, and economic importance considerably greater than might be expected. The objective of this work was to determine the concentration of the lanthanides (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu), and U, considering the soil use and occupation from the Jaguari river basin, Sao Paulo. Instrumental Neutron Activation Analysis (INAA) was used for the REE and U analysis The study area is located in a traditional agricultural area which is nowadays one of the main industrial regions of Brazil. In order to evaluate the quality of these soils in relation to lanthanides and U levels, the obtained concentrations were compared to guiding values reported by environmental protection agencies. The 75th percentile for U in agricultural soils (2.76 mg kg-1) was higher than in the control areas (1.61 mg kg-1), but much lower than the maximum allowed concentration for soils in The Netherlands (28.3 mg kg-1). The lanthanides presented concentration levels higher than the guiding values of the RIVM - -National Institute for Public Health and the Environment guidelines. (author)