Distribution of radionuclides and elements in Cubatão River sediments

Cubatao River is located in Santos Basin, Sao Paulo State, Brazil. This region is characterized by the occurrence of estuaries and mangrove. Due to its location, near the coastal line, it is also an important industrial area, where phosphate fertilizer plants, petrol refineries, and chemical and steel industries are present. Such human activities contribute to the enhancement of elemental composition in sediments and, in some cases, also increase the radionuclide concentrations, the so called Technologically Enhanced Natural Occurring Radioactive Materials (TENORM). The contamination of land and sediments by TENORM is of major concern. The activity concentration of U and Th series radionuclides was determined in five sediment samples from Cubatao River. The activity concentration ratio was also determined. Equilibrium was observed for the ratio super(234)U/ super(238)U. The activity ratios of Th/ super(238)U, super(228)Ra/ super(226)Ra and super(210)Pb/ super(226)Ra were higher than the unity. In the first two cases, the observed values are due to the higher activity of Th in the sediment and in the last case are probably due to the atmospheric deposition of super(210)Pb.