The aim of this study is to evaluate total arsenic (As) concentrations in drinking water (main pathway of human exposure) and its hydrogeochemical controls in the "Morro do Ouro" gold mine region, which is the largest gold mine in Brazil, characterized by gold-arsenopyrite association. Arsenic concentration was generally below the detection limit (LOD < 0.5 μg L(-1)). Thus, water ingestion may not be a significant exposure pathway to local population. Low groundwater As concentrations (<1 μg L(-1)) are likely due to ore body structural setting, which plunges from 10° to >20°, being readily covered by thick phyllites that are poor in As some hundreds of meters away from the mine. Thirty-five percent of As levels in superficial waters (<0.5 to 40 μg L(-1)) were >10 μg L(-1), which is the maximum permissible value for human ingestion. The highest concentrations were found nearby mine facilities and old artisanal mining areas surrounding the mine, decreasing downstream. Undisturbed watersheds showed As concentrations close to LOD. Hydrogeochemical data stress the sorption (adsorption and co-precipitation) of As role, mainly by Fe oxyhydroxides, as a geochemical filter that retains As, attenuating its concentration in both superficial and groundwater. Such minerals are abundant in the region oxisols, sediments, and phyllites and may form stable mineral complexes with As under the pH (mostly neutral) and Eh (reduced environment) conditions found in the field. It has been demonstrated that As(III) (more toxic) and As(V) co-exist in the analyzed waters and that As(V) predominates in superficial water.
Arsenic (As) is a dangerous and carcinogenic element and drinking water is its main pathway of human exposure. Gold mines are widely recognized as important sources of As pollution. This work proposes the assessment of As distribution along watersheds surrounding "Morro do Ouro" gold mine (Paracatu, southeastern Brazil). A balance approach between filtered As fluxes (As < 0.45 μm) and suspended particulate material (AsSPM) in different river segments was applied. Ultrafiltration procedure was used to categorize As into the following classes: particulate > 0.1 μm, colloidal < 0.1 μm to > 10 kDa, dissolved < 10 kDa to > 1 kDa, and truly dissolved < 1 kDa. By applying this approach, arsenic contributions from mining facilities were quantified in order to identify critical fluvial segments and support decision makers in actions of remediation. The mass balance indicated the occurrence of a decreasing gradient from upstream to downstream: (i) of the As concentrations higher than the limit established by Brazilian law (10 μg L); (ii) of the ratio between specific fluxes (g As km day) and those determined using an uncontaminated watershed (a proxy for estimating the anthropic contribution), from 103 to 101; (iii) of the specific fluxes As < 0.45 μm and AsSPM from 102 to 100; and (iv) of the negative balance output minus input for each river segment that suggests As accumulation in sediments along the rivers in both urban and rural areas, mainly due to SPM sedimentation and sorption by Fe oxyhydroxides. Ultrafiltration shattering showed concentrations of decreasing As with particle size; the SPM load (> 0.1 μm) was almost one order higher to dissolved load (< 1 kDa).
ResumoOs riscos potenciais à saúde humana associados à presença de elementos traços (Ba, B, Ni, Hg, Zn, Mg, Ca, K, P, Na, Cl -, F -) e patógenos fecais foram avaliados em 12 poços de captação de água subterrânea em Capitão Gervásio de Oliveira, Piauí. A metodologia de avaliação de risco à saúde humana proposta pela Agência Americana de Proteção Ambiental foi utilizada para a estimativa numérica dos riscos relacionados à exposição ambiental por Ni, Hg, Zn, B e Ba. A determinação dos coliformes totais e de Escherichia coli foi realizada com o emprego do método Colilert. Todas as concentrações obtidas foram comparadas aos padrões de qualidade recomendados pela legislação brasileira. Os resultados mostraram que os teores da maior parte dos elementos estudados estão abaixo dos valores máximos estipulados pela legislação, com exceção do Hg, Ni e Cl -. Todos os poços estudados mostram águas inapropriadas para o consumo humano quando se considera a contaminação por coliformes. Ainda, a estimativa numérica do risco total à saúde humana indicou que o Ni e o Hg são os metais que mais efetivamente participam do acréscimo de perigo, devendo ser priorizados em ações que decresçam os teores desses metais-traço nas águas consumidas pela população. Palavras-chave: águas subterrâneas, semiárido, saúde humana, risco. AbstractPotential risks on human health associated with trace elements (Ba, B, Ni, Hg, Zn, Ni, Mg, Ca, K, P, Na, Cl -, F -) and fecal pathogens exposure were evaluated in 12 groundwater samples from supply wells at the Capitão Gervásio de Oliveira Municipality, Piauí, Brazil. The methodology for human health risk assessment, established by the American Agency for Environmental Protection, was applied in order to numerically estimate the risks associated with Ni, Hg, Zn, B and Ba exposure. Total coliforms and Escherichia coli were quantified using the Colilert method. The concentrations were compared to the values defined by the Brazilian environmental law. The results revealed that most concentrations were in disagreement with the values defined by the Brazilian legislation, especially Hg, Ni and Cl -. In terms of coliforms pollution, all samples were inappropriate for human consumption. The numerical estimation of the total risks on human health indicated that Ni and Hg are the metals that most effectively increase the hazard, suggesting that actions should be focused on decreasing such levels in drinking water.
A gestão e a obrigatoriedade do estabelecimento de sistemas de logística reversa de resíduos eletroeletrônicos (REEE) no Brasil foram definidas pela Política Nacional de Resíduos Sólidos (PNRS). A partir do Decreto nº 10.240/2020 foram informados 215 produtos para os quais foram estabelecidos prazos e metas para a coleta e destinação ambientalmente adequada. Este documento estabelece metas a anuais não cumulativas a partir do ano de 2021 até 2025, tendo como base o volume em peso dos produtos eletroeletrônicos colocados no mercado interno no ano-base de 2018. Desta forma, o presente estudo objetivou quantificar o volume médio comercializado no Brasil em 2018 a partir da metodologia adotada pela Europa, utilizando dados do IBGE (base SIDRA) sobre a produção e dados sobre importação e exportação informados pela Receita Federal. Os resultados indicaram que, dentro das categorias especificadas pelo decreto, o sistema de logística reversa de REEE deverá recolher cerca de 17,8 kt de REEE ao final do ano de 2021, montante equivalente a 1% do volume colocado no mercado (VCM), calculado em 1,78 milhões de toneladas para 12% dos produtos listados no decreto, no ano-base de 2018, evidenciando um significativo potencial para a recuperação de materiais secundários a partir dos REEE.
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