Mineralogy and Arsenic Mobility in Arsenic-rich Brazilian Soils and Sediments (11 pp)

Mello, Jaime Wilson Vargas de; Roy, William R.; Talbott, Jonathan L.; Stucki, Joseph W.

doi:10.1065/jss2005.09.144

Cited by 58 publications

(35 citation statements)

References 29 publications

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“…In the 19th century, Minas Gerais was extensively explored by gold mining activities and, as consequence, there are still many non-identified abandoned passives and contamination hot spots, especially in the Iron Quadrangle region Mello et al 2006;Windmöller et al 2007). In this respect, indiscriminate uses of Hg are historically well documented in Minas Gerais (Windmöller et al 2007), especially in small-scale gold mining sites for processing alluvial deposits.…”

Section: Introductionmentioning

confidence: 98%

Mercury, copper and zinc contamination in soils and fluvial sediments from an abandoned gold mining area in southern Minas Gerais State, Brazil

et al. 2010

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Mercury, zinc and copper contamination was evaluated in soils and fluvial sediments from an abandoned gold mining site at Descoberto Municipality (southern Minas Gerais State, Brazil). Metals bioavailability and potential mobility were studied through physical, chemical and mineralogical characterization, geoaccumulation indexes calculations, mercury speciation and determination of potentially bioavailable contents of zinc and copper. Values of pH were in the neutral range, while organic matter concentrations were very low. Mineralogical characterization, in the total samples, indicated the presence of quartz, kaolinite and gibbsite for all samples. Total mercury, zinc and cooper concentrations were higher than the limits recommended by Brazilian documents. Geoaccumulations indexes revealed that most of the sediment samples were low to moderately polluted by zinc and copper, while just one sample was very strongly polluted by mercury. Mercury speciation revealed the predominance of the elementary form for all samples, and low concentrations for exchangeable, strongly bound and residual fractions. Zinc and copper behavior was strongly controlled by iron and aluminum concentrations, while their bioavailable contents were very low in comparison with the total concentrations.

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Section: Introductionmentioning

confidence: 98%

Mercury, copper and zinc contamination in soils and fluvial sediments from an abandoned gold mining area in southern Minas Gerais State, Brazil

et al. 2010

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“…The area has been the most important gold producing region in Brazil since the end of the seventeenth century, with a total production exceeding 1,300 tons (Borba et al 2003). In IQ mineral deposits, As is found in close association with sulfide-rich gold-bearing rocks (Matschullat et al 2000;Mello et al 2006). The most abundant sulfide minerals are pyrite (FeS 2 ), arsenopyrite (FeAsS), and pyrrhotite (Fe 1−x S) (Matschullat et al 2000;Vial et al 2007), yet trace metal sulfides occur in subordinate phases as well (Gonçalves et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Arsenic and trace metals in river water and sediments from the southeast portion of the Iron Quadrangle, Brazil

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et al. 2010

Environ Monit Assess

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The Iron Quadrangle has been one of the most important gold production regions in Brazil since the end of the seventeenth century. There, arsenic occurs in close association with sulfide-rich auriferous rocks. The most abundant sulfide minerals are pyrite and arsenopyrite, yet trace metal sulfides occur in subordinate phases as well. Historical mining activities have been responsible for the release of As and trace metals to both aquatic and terrestrial environments close to mining sites in the region. Therefore, this study was aimed to evaluate the distribution and mobility of As, Cd, Co, Cr, Cu, Ni, Pb, and Zn in streams in the southeast portion of the Iron Quadrangle between the municipalities of Ouro Preto and Mariana, the oldest Brazilian Au mining province. Total concentrations of some trace metals and arsenic in water were determined. The four-stage sequential extraction procedure proposed by the commission of the European Communities Bureau of Reference (BCR) was used to investigate the distribution of these elements in stream sediments. Arsenic concentration in water was > 10 μg L⁻¹ (maximum limit permitted by Brazilian environmental regulations for water destined for human consumption) at all sampling sites, varying between 36.7 and 68.3 μg L⁻¹. Sequential extraction in sediments showed high concentrations of As and trace metals associated with easily mobilized fractions.

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“…1), which has an extensive iron-ore mining and processing plant. Various studies have confirmed the environmental contamination by trace metals in the Iron Quadrangle (de Mello et al 2006;Matschullat et al 2000;Pimentel et al 2003). However, most of these studies were concentrated in gold mining areas, focused on arsenic and mercury contamination, and did not include information about metal bioavailability.…”

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confidence: 99%

Effects of iron-ore mining and processing on metal bioavailability in a tropical coastal lagoon

et al. 2008

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Background, aim, and scope In water systems, water quality and geochemical properties of sediments determine the speciation of trace metals, metal transport, and sediment-water exchange, influencing metal availability and its potential effects on biota. Studies from temperate climates have shown that iron-ore mining and tailing wastewaters, besides being a source of trace metals, usually show high levels of dissolved ions and particulate suspended matter, thus having the potential of indirectly changing metal bioavailability. For the first time in the tropics, we identified the effects of iron-ore mining and processing on metal bioavailability in a coastal lagoon. With an extensive sampling scheme, we investigated the potential sources of metals; the links among metal levels in water, sediments, and invertebrates; and the contrasting effects on metal speciation and bioavailability. Methodology The metals Fe, Mn, Al, Cr, Zn, Cu, Ni, Pb, Cd, Hg, and As were measured in water, sediments (surface and profiles), and invertebrates from Mãe-Bá Lagoon and in the sites directly influenced by the mining operations (tailing dams and nearby rivers). In addition, samples from two other lagoons, considered pristine, were analyzed. The study area is located in the southeast of Brazil (Iron Quadrangle Region and a coastal area of Espírito Santo State). General water characteristics included pH, dissolved organic carbon, alkalinity, and anion composition. Water metal speciation was assessed by a speciation model (Chemical Equilibria in Aquatic Systems). Grain-size distribution, organic carbon, carbonate, and acid volatile sulfide (AVS) were determined in sediments. Statistical methods included comparison of means by Mann-Whitney test, ordination and correlation analyses, and analysis of regression for geochemical normalization of metals with grain size. Results and discussion The dissolved metal concentrations, the total metal levels in sediments, and the normalization based on the fine sediment fraction showed that the mining operations constitute potential sources of Fe, Mn, Cr, Cu, Ni, Pb, As, and Hg to Mãe-Bá Lagoon. However, trace metal availability was reduced because of increased pH, hardness, and sulfide content (356 μmol/g) in the sites influenced by the mining. The lagoon showed similar water chemistry as in the mining sites, with metal bioavailability further decreased by the presence of dissolved organic carbon and chloride. Although AVS levels in the lagoon were low (0.48-56 μmol/g), metal bioavailability was reduced because of the presence of organic matter. Metal levels in invertebrates confirmed the predicted low metal bioavailability in Mãe-Bá Lagoon. The lagoon was considered moderately contaminated only by Hg and As. Conclusions The iron-ore mining and processing studied here constitute potential sources of metal pollution into the tropical lagoon. Contrary to expectations, however, it also J Soils Sediments

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Mineralogy and Arsenic Mobility in Arsenic-rich Brazilian Soils and Sediments (11 pp)

Cited by 58 publications

References 29 publications

Mercury, copper and zinc contamination in soils and fluvial sediments from an abandoned gold mining area in southern Minas Gerais State, Brazil

Mercury, copper and zinc contamination in soils and fluvial sediments from an abandoned gold mining area in southern Minas Gerais State, Brazil

Arsenic and trace metals in river water and sediments from the southeast portion of the Iron Quadrangle, Brazil

Effects of iron-ore mining and processing on metal bioavailability in a tropical coastal lagoon

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