Investigations into Pb isotope signatures in groundwater and sediments in a uranium-mineralized area

Investigações isotópicas de Pb em águas subterrâneas e sedimentos de uma área mineralizada em urânio

ABSTRACT:

This work presents the investigation in an environment that contains uranium deposits by using Pb isotope signatures. The study area, southeast of Brazil, is characterized by the lack of surface water and, as a consequence, the groundwater plays an important role in the economy of the region, such as the supply to the uranium industry and, above all serving the needs of the local population. The objective of the present investigation is the determination of the signatures of Pb in groundwater and sediments as well as the identification of environments under influences of geogenic and/or anthropogenic sources. It was determined that the Pb in the majority of sediments was geogenic in origin. Although data from the literature, related to the environmental studies, consider ²⁰⁶Pb/²⁰⁷Pb isotopic ratio values below or close to 1.2 as an indicative of anthropogenic Pb, the ²⁰⁶Pb/ ²⁰⁷Pb determined for the majority of groundwater samples ranged from 1.14 to 1.19, and are similar to the data reported for rocks samples (1.09 to 1.96) from area with U mineralization. It was also determined that the anthropogenic influence of the uranium was restricted to a single sampling point within the mining area.

KEYWORDS:
Lead stable isotopes; Anthropogenic; Geogenic; Radiogenic Pb; Environmental monitoring