Uranium, thorium, gross alpha and gross beta assessment in fountain waters in towns of the Iron Quadrangle, Brazil

The Iron Quadrangle region is known worldwide for its diversity, both ores and rock types, which record a long and important period of Earth's history. For thousands of years erosive processes have exposed ancient rocks, Archean and Proterozoic, in this region. The concentration of uranium, thorium, gross alpha and gross beta activities has been assessed in 34 fountains water samples collected from different towns in the Iron Quadrangle. The results obtained were compared to values established by CONAMA nº 396/2008 and Decree nº 2914/2011 by the Ministry of Health. For Th in water consumption there is no value established in the Brazilian legislation and the concentrations in all samples were lower than 0.01 μg L-1. For uranium, the values ranged from less than 0.002 to 0.61 μg L-1, and all results were lower than the value allowed of 15 μg L-1 and 30 μg L-1 established by the legislations above, respectively. The results for the radiation levels of gross alpha and gross beta activity in some fountains waters were slightly above the limits (0.5 Bq L-1 and 1.0 Bq L-1) established by CONAMA nº 396/2008 and Decreet nº 2914/2011, respectively. (author)