title: Hydrogeochemistry of arsenic pollution in watersheds influenced by gold mining activities in Paracatu (Minas Gerais State, Brazil).
abstract: 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.
authors.affiliation: Department of Environmental Geochemistry, Fluminense Federal University, UFF, Outeiro São João Batista, s/n. Centro, Niterói, RJ, Brazil. ebidone@yahoo.com.br.
authors.forename: Edison
authors.initials: E
authors.lastname: Bidone
authors.affiliation: Department of Environmental Geochemistry, Fluminense Federal University, UFF, Outeiro São João Batista, s/n. Centro, Niterói, RJ, Brazil.|Center for Mineral Technology, CETEM/MCTI, Cidade Universitária, Av. Pedro Calmon, 900, Rio de Janeiro, RJ, Brazil.
authors.forename: Zuleica
authors.initials: Z
authors.lastname: Castilhos
authors.affiliation: Department of Geography, Federal University of Rio de Janeiro, UFRJ, Av. Athos da Silveira Ramos, 274-Cidade Universitária, Rio de Janeiro, RJ, Brazil.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Cesar
authors.affiliation: Department of Environmental Geochemistry, Fluminense Federal University, UFF, Outeiro São João Batista, s/n. Centro, Niterói, RJ, Brazil.
authors.forename: Maria Carla
authors.initials: MC
authors.lastname: Santos
authors.affiliation: Department of Environmental Geochemistry, Fluminense Federal University, UFF, Outeiro São João Batista, s/n. Centro, Niterói, RJ, Brazil.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Sierpe
authors.affiliation: Department of Environmental Geochemistry, Fluminense Federal University, UFF, Outeiro São João Batista, s/n. Centro, Niterói, RJ, Brazil.
authors.forename: Marcos
authors.initials: M
authors.lastname: Ferreira
mesh_terms: D001151:Arsenic / Q000032:analysis*; D001152:Arsenicals; D001938:Brazil; D004777:Environment; D004784:Environmental Monitoring; D006046:Gold; D060587:Groundwater / Q000737:chemistry; D006801:Humans; D058085:Iron Compounds; D008903:Minerals; D008906:Mining; D013440:Sulfides; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data*
chemical_list: D001152:Arsenicals; D058085:Iron Compounds; D008903:Minerals; D013440:Sulfides; D014874:Water Pollutants, Chemical; C064510:arsenopyrite; D006046:Gold; D001151:Arsenic
keywords: Arsenic; Contamination; Drinking water; Groundwater; Risk attenuation; Superficial water