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

A area de estudo relaciona-se com o Complexo Minero Industrial do Planalto de Pocos de Caldas (CIPC), gerador de um efluente acido que, apos tratado, e descartado na Represa de Aguas Claras que devido a ineficiencia do processo de precipitacao e subdimensionamento dos tanques de decantacao, tem atuado como uma especie de bacia de retencao dos contaminantes. A represa verte no Ribeirao das Antas que atravessa a cidade de Pocos de Caldas, localizada a jusante do empreendimento minerario. De forma a se produzir diagnosticos mais fieis a area de estudo, considerando-se os varios processos ocorridos e a correlacao entre elemento e a fonte que a originou (geogenica ou antropogenica), a ferramenta isotopica de Pb, atraves dos isotopos estaveis 204Pb, 206Pb, 207Pb e 208Pb, foi utilizada para obter informacoes sobre a atuacao dos elementos radioativos U e Th, naturalmente presentes na regiao e intensificados pela drenagem acida de rocha (DAR). As informacoes obtidas possibilitaram avaliar o impacto ambiental causado pelo lancamento do efluente acido tratado pelo CIPC em sedimentos da Represa de Aguas Claras e do Ribeirao das Antas. As assinaturas isotopicas de Pb das amostras de sedimentos foram comparadas as assinaturas de rochas preservadas e, coletadas dentro e fora da cava da mina Osamu Utsumi, as quais representam o registro do ambiente geogenico e/ou natural. A utilizacao dos diagramas 208Pb/204Pb versus 206Pb/204Pb e 206Pb/207Pb versus 1/Pb, possibilitou o diagnostico de ambientes com influencias antropicas em urânio (U) e de fontes geogenicas na area de estudo. Palavras-chave: Isotopos estaveis de Pb, assinaturas isotopicas, sedimentos, identificacao de fontes Abstract: SIGNATURES Pb ISOTOPIC IN EVALUATING THE ENVIRONMENTAL IMPACT CAUSED BY WASTEWATER TREATED BY LAUNCH COMPLEX MINERO INDUSTRIAL OF POCOS CALDAS WELLS OF PLATEAU IN CLEAR WATERS OF DAM AND RIBEIRAO ANTAS. The study area is related to the Industrial the Mining Complex of Pocos 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 Ribeirao das Antas through the city of Pocos 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 Ribeirao 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