Environmental assessment of water from a uranium mine (Caldas, Minas Gerais State, Brazil) in a decommissioning operation

Autor: Suzelei Rodgher, Heliana de Azevedo, M.R.L. Nascimento, Cláudio Vitor Roque, Michelle Burato de Campos
Rok vydání: 2010
Předmět:
Zdroj: Environmental Earth Sciences. 62:857-863
ISSN: 1866-6299
1866-6280
DOI: 10.1007/s12665-010-0572-9
Popis: The present study was carried out in a uranium ore mining area located in Caldas, in the southern region of the state of Minas Gerais, Brazil. The present study was undertaken to evaluate the ecologies of populations of the bioleaching microorganisms (Acidithiobacillus ferrooxidans and A. thiooxidans) in effluents from mining companies containing sulfides and associated radionuclides, and to assess the physico-chemical and radiological uranium mining impact on surface water quality. Water samples collected from eight points were analyzed chemically and microbiologically. In water samples from points in the region called the pit mine–waste rock piles, high average oxide-reduction potential value (429–525 mV), high ferrous ion concentration (0.72–12.56 mg L−1), low average pH value (3.37–3.47) and highest average population densities of A. ferrooxidans (59–2,551 MPN mL−1) and A. thiooxidans (833–6,359 MPN mL−1) were detected. These findings indicate that these points are the main places of acid mine drainage and biolixiviation action in the Ore Treatment Unit (UTM). The study reported here also found that water quality in the point considered a link between the UTM and the environment was degraded. These points should be considered as critical sites in the event of a decommissioning act. The average concentration values of fluorite (10.60 mg L−1) and manganese (10.49 mg L−1) in the water samples of treated effluents are above the limits permitted by law. Long-term utilization of these waters is considered to be unhealthy for the local environment and humans.
Databáze: OpenAIRE
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