Geoquímica de radionuclídeos naturais e biomonitoramento em área de mineração de carvão no sul do Brasil
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Data
2016-04-06
Autores
Galhardi, Juliana Aparecida [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O carvão mineral representa a maior fonte de combustível não renovável no Brasil para geração de energia elétrica. Em Figueira, Paraná, o carvão extraído pela Companhia Carbonífera do Cambuí abastece a termelétrica do município e faz parte da maior reserva ainda em exploração no estado, tendo sido lá registrada a ocorrência anômala de urânio. Para a avaliação de impactos radiológicos associados às atividades de extração, beneficiamento e queima do carvão mineral na área, foi realizada uma avaliação da composição das águas e solos amostrados na área em termos químicos e radiométricos, além do uso de organismos como biomonitores para a verificação dos níveis de contaminação atmosférica e dos solos. Por meio das análises, realizadas no Laboratório de Isótopos e Hidroquímica - Unesp, Rio Claro, Brasil, e no Laboratório de Física Nuclear Aplicada - Universidade de Sevilha, Sevilha, Espanha, foi observado que efluentes ácidos são originados a partir da oxidação de minerais de sulfeto e resultam em um acréscimo da taxa de solubilização de radionuclídeos nas águas subterrâneas e superficiais da região. À jusante da área da mineração, o pH nas águas dos rios foi mais ácido e o teor de algumas espécies químicas mais elevado, o que pode ser devido à descarga de efluentes ácidos provenientes da mineração. O mesmo comportamento foi verificado para os solos. Nas águas subterrâneas, as concentrações de atividade dos radionuclídeos foram notavelmente mais elevadas nas áreas de processamento do carvão, de disposição dos rejeitos e à jusante da planta da mina. Por meio do biomonitoramento, a eficácia de algumas espécies de líquens e musgos como bioindicadores da qualidade do ar em áreas afetadas por mina de carvão e termelétrica foi testada e comprovada, sendo que o 210Po foi o radionuclídeo que apresentou as maiores concentrações de atividade nas espécies investigadas. Por meio das razões 234U/238U foi possível verificar a infiltração de efluentes ácidos nas águas subterrâneas, assim como uma contribuição das cinzas lançadas pela termelétrica para o conteúdo dos radionuclídeos nos solos, sedimentos e também para os líquens, musgos, soja e trigo. O transporte dos radionuclídeos reflete a importância do monitoramento da concentração de suas atividades nas águas naturais, solos e na biota, devido aos riscos que a radioatividade pode representar para a saúde humana.
Coal represents the largest source of non-renewable fuels in Brazil for electric power generation. In the city of Figueira, Paraná State, the coal extracted by Cambuí Company supplies the thermal power plant in the city and is part of the largest reserve that is nowadays being exploited in the area, where it was registered anomalous occurrence of uranium. For the evaluation of radiological impacts associated with the extraction, processing and burning of coal in the area, it was carried out an investigation of the water and soil chemical and radiological composition and some organisms were evaluated as biomonitors for the investigation of the air and soil pollution. Through the analysis, carried out in the Laboratório de Isótopos e Hidroquímica - Unesp, Rio Claro, Brazil, and Laboratorio de Física Nuclear Aplicada - Universidad de Sevilla, Spain, it was observed that acid effluents are generated from the oxidation of sulfide minerals and can result in an increase in the solubilization rate of radionuclides, enhancing the possibility of groundwater and soil contamination at levels of difficult treatment and recovery. Downstream of the mining area, the pH in the rivers waters was more acidic and the content of some chemical species was higher, probably due to the discharge of acid effluent from the mine. The same behavior was observed for the soils. In groundwater, the radionuclides activity concentrations were significantly higher in the areas of the coal industrial processing and in the tailings pile and downstream of the mine. Through the biomonitoring, the efficiency of some species of lichens and mosses as bioindicators of the air quality in areas affected by coal mine and thermal power plant has been tested and proven. 210Po was the radionuclide that showed the highest activity concentration in the investigated species. Through the 234U/ 238U rates it was observed the infiltration of acidic effluents into the groundwater, as well as a contribution of the fly ashes from the thermal plant for the radionuclides content in soils, sediments and also in lichens, mosses, soybeans and wheat. The radionuclides transport reflects the importance of monitoring the concentration of its activities in natural waters, soil and also in the biota due to the risks that radioactivity can represents to human health.
Coal represents the largest source of non-renewable fuels in Brazil for electric power generation. In the city of Figueira, Paraná State, the coal extracted by Cambuí Company supplies the thermal power plant in the city and is part of the largest reserve that is nowadays being exploited in the area, where it was registered anomalous occurrence of uranium. For the evaluation of radiological impacts associated with the extraction, processing and burning of coal in the area, it was carried out an investigation of the water and soil chemical and radiological composition and some organisms were evaluated as biomonitors for the investigation of the air and soil pollution. Through the analysis, carried out in the Laboratório de Isótopos e Hidroquímica - Unesp, Rio Claro, Brazil, and Laboratorio de Física Nuclear Aplicada - Universidad de Sevilla, Spain, it was observed that acid effluents are generated from the oxidation of sulfide minerals and can result in an increase in the solubilization rate of radionuclides, enhancing the possibility of groundwater and soil contamination at levels of difficult treatment and recovery. Downstream of the mining area, the pH in the rivers waters was more acidic and the content of some chemical species was higher, probably due to the discharge of acid effluent from the mine. The same behavior was observed for the soils. In groundwater, the radionuclides activity concentrations were significantly higher in the areas of the coal industrial processing and in the tailings pile and downstream of the mine. Through the biomonitoring, the efficiency of some species of lichens and mosses as bioindicators of the air quality in areas affected by coal mine and thermal power plant has been tested and proven. 210Po was the radionuclide that showed the highest activity concentration in the investigated species. Through the 234U/ 238U rates it was observed the infiltration of acidic effluents into the groundwater, as well as a contribution of the fly ashes from the thermal plant for the radionuclides content in soils, sediments and also in lichens, mosses, soybeans and wheat. The radionuclides transport reflects the importance of monitoring the concentration of its activities in natural waters, soil and also in the biota due to the risks that radioactivity can represents to human health.
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Palavras-chave
Radioatividade natural, Carvão mineral, Biomonitoramento, Água subterrânea, Natural radioactivity, Coal, Biomonitoring, Groundwater