Analysis of the Gamma Spectrometry ~(210)Pb Radioisotope in River Bottom Sediments of the Hydrographic sub-basins Around the UTM-Caldas

摘要

The uranium mine of Caldas, currently named Ore Treatment Unit (UTM-Caldas), is sited at the Pocos de Caldas Plateau (Minas Gerais State) and was the first uranium mineral-industrial complex in Brazil. It has been installed since 1982 and now it is under decommissioning process. Taking into account the potential sources of contamination and the assessment of the impact of the mine, based on the presence of radionuclides from the radioactive decay series of natural ~(238)U, the aim of the article is to present the distribution of ~(210)Pb in the stream bottom sediments of the study area that consists of the Taquari watershed, sub-divided by its three major sub-basins: Consulta stream, Soberbo stream and Taquari river. The radionuclide activity concentrations were measured in sediment samples that were collected in twelve collecting points, during four sampling campaigns, carried out in the dry and rainy seasons of 2010 and 2011. The results of the ~(210)Pb concentration activity were obtained by gamma spectrometry performed in both high and low energy CANBERRA detectors. The results point out that the UTM-Caldas is influencing on the bottom sediment distribution of ~(210)Pb activity in its neighborhood. However, a more detailed study should be done in order to identify if there is another source of ~(210)Pb in the study area, such as a geogenic anomaly, that may contributing to the local increment of ~(210)Pb activity.