ASSINATURAS ISOTÓPICAS DE Pb NA AVALIAÇÃO DO IMPACTO AMBIENTAL CAUSADO PELO LANÇAMENTO DO EFLUENTE TRATADO PELO COMPLEXO MÍNERO INDUSTRIAL DO PLANALTO DE POÇOS DE CALDAS NA REPRESA DE ÁGUAS CLARAS E RIBEIRÃO DAS ANTAS

Abstract

A área de estudo relaciona-se com o Complexo Mínero Industrial do Planalto de Poços de Caldas (CIPC), gerador de um efluente ácido que, após tratado, é descartado na Represa de Águas Claras que devido à ineficiência do processo de precipitação e subdimensionamento dos tanques de decantação, tem atuado como uma espécie de bacia de retenção dos contaminantes. A represa verte no Ribeirão das Antas que atravessa a cidade de Poços de Caldas, localizada a jusante do empreendimento minerário. De forma a se produzir diagnósticos mais fiéis à área de estudo, considerando-se os vários processos ocorridos e a correlação entre elemento e a fonte que a originou (geogênica ou antropogênica), a ferramenta isotópica de Pb, através dos isótopos estáveis 204Pb, 206Pb, 207Pb e 208Pb, foi utilizada para obter informações sobre a atuação dos elementos radioativos U e Th, naturalmente presentes na região e intensificados pela drenagem ácida de rocha (DAR). As informações obtidas possibilitaram avaliar o impacto ambiental causado pelo lançamento do efluente ácido tratado pelo CIPC em sedimentos da Represa de Águas Claras e do Ribeirão das Antas. As assinaturas isotópicas de Pb das amostras de sedimentos foram comparadas às assinaturas de rochas preservadas e, coletadas dentro e fora da cava da mina Osamu Utsumi, as quais representam o registro do ambiente geogênico e/ou natural. A utilização dos diagramas 208Pb/204Pb versus 206Pb/204Pb e 206Pb/207Pb versus 1/Pb, possibilitou o diagnóstico de ambientes com influências antrópicas em urânio (U) e de fontes geogênicas na área de estudo.Palavras-chave: Isótopos estáveis de Pb, assinaturas isotópicas, sedimentos, identificação de fontesAbstract: SIGNATURES Pb ISOTOPIC IN EVALUATING THE ENVIRONMENTAL IMPACT CAUSED BY WASTEWATER TREATED BY LAUNCH COMPLEX MINERO INDUSTRIAL OF POÇOS CALDAS WELLS OF PLATEAU IN CLEAR WATERS OF DAM AND RIBEIRÃO ANTAS. The study area is related to the Industrial the Mining Complex of Poços Caldas Plateau (CIPC), generating an acid effluent, after treated, is disposed in Clearwater Dam that due to the inefficiency of the precipitation process and undersize of settling tanks, it has acted as a kind of contaminant retention basin. The dam spills in Ribeirão das Antas through the city of Poços Caldas, located downstream of the mining enterprise. In order to produce more faithful to the study site diagnostics considering the various occurring processes and the correlation between the element and the source from which it originated (geogenic or anthropogenic), isotopic tool Pb through 204 Pb stable isotope 206Pb , 207Pb and 208Pb, was used to obtain information about the activities of radioactive elements U and Th, naturally present in the region and intensified by acid drainage rock (DAR). The information obtained allowed assessing the environmental impact of the release of effluent treated by acid CIPC in sediments of Aguas Claras Dam and Ribeirão das Antas. The Pb isotopic signatures of sediment samples were compared to preserved rocks and signatures, collected in and out of the pit of the Osamu Utsumi mine, which represent the registration of geogenic and / or natural environment. The use of diagrams 208Pb/204Pb versus 206Pb/204Pb and 206Pb/207Pb versus 1/Pb, enabled the diagnosis of environments with anthropogenic influences uranium (U) and geogenics of sources in the study area.Keywords: Lead stable isotopes, isotopic fingerprinting, sediments, source identification

Application of Multivariate Statistic of U, Th and Pb Concentrations and Pb Isotopic Signatures in the Assessment of Geogenic and Anthropogenic Sources in a U-Mineralized Area

“…Considering that physical or chemical processes do not affect the isotopic composition of Pb in the environment (Doe, 1970;Bollhöfer et al, 1999), the Pb signature tends to be identical to the source that originated it. Therefore, the isotopic signatures of Pb of anthropogenic provenance are distinct from the isotopic signature of natural origin, and can be used as a tracer of the possible sources of Pb in the environment (Bollhöfer et al, 1999;Bollhöfer and Rosman, 2000;Bollhöfer and Rosman, 2001;Chen et al, 2005;Gioia et al, 2006;Gulson et al, 2007;Komárek et al, 2008;Gioia et al, 2010;Vecchia, 2015;Vecchia et al, 2015;Vecchia et al, 2017a and2017b).…”

“…According to Vecchia (2015), Vecchia et al (2015) and Vecchia et al (2017a and2017b), the use of the Pb isotopic tool to study environmentally impacted areas requires knowledge of the Pb isotopic signatures of geographic samples as a determinant factor in the investigative process of environmental matrices.…”

“…(Manly, 2005;Mingoti, 2007;Zhao et al, 2011, Cavalcante et al, 2013Sun et al, 2013;Siepak and Sojka, 2017). It is important to emphasize that the results obtained with these techniques should, whenever possible, be confronted with information related to the research context, seeking an association on the possible processes in the study region (Vecchia, 2015;Vecchia et al, 2015;Vecchia et al, 2017a and2017b).…”