Navegando por Autor "Morgenstern, Peter"

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    Arsenic speciation in plant samples from the Iron Quadrangle, Minas Gerais, Brazil.
    (2005) Daus, Birgit; Wennrich, Rainer; Morgenstern, Peter; Weiß, Holger; Palmieri, Helena Eugênia Leonhardt; Nalini Júnior, Hermínio Arias; Leonel, Liliam Viana; Monteiro, Roberto Pellacani Guedes; Moreira, Rubens Martins
    Several plants, especially ferns, have been shown to tolerate and accumulate high arsenic concentrations in soils. The leaves and roots of the ferns Pteris vittata (Chinese brake) and Pityrogramma calomelanos as well as a medical plant (Baccharis trimera) were sampled together with their associated soils in a region impacted by ore mining, the Iron Quadrangle in Brazil, where arsenic concentrations in the soils vary sharply (6–900 mgg 1). The bioaccumulation factors were found to be low compared to the literature data, which can be explained by the low water-soluble fraction of arsenic in soil. The arsenic species in the plants were mainly arsenite. In comparison to the rhizoid samples, the concentrations of arsenic were higher in the leaves of the fern samples. The medical plant behaved differently. The bioaccumulation factor was low (0.7), and trimethylarsine oxide was detected as the third arsenic species beside arsenite and arsenate in both the roots and the leaves.
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    Sediment contamination in floodplains and alluvial terraces as an historical record of gold exploitation in the Carmo River basin, Southeast Quadrilátero Ferrífero, Minas Gerais, Brazil.
    (2006) Costa, Adivane Terezinha; Nalini Júnior, Hermínio Arias; Castro, Paulo de Tarso Amorim; Lena, Jorge Carvalho de; Morgenstern, Peter; Friese, Kurt
    This paper describes the geochemistry of sediment samples placed in floodplains and alluvial terraces downstream from gold mines in the Carmo River basin, Quadril tero Ferr fero, Minas Gerais, Brazil. The geochemistry signature Na2O, K2O, SiO2, CaO, MgO, Al2O3, Fe2O3, TiO2, P2O5, Mn, As, Cu, Zn, Ba, Ni, Cr, S, Co were analyzed in different facies from stratigraphic profiles. As, Cu, Zn, and Mn anomalies are mainly associated with the clayed facies deposited in floodplains and oxbow lakes, and with coarse-sediment facies deposited in the channel. The facies were accumulated by the gold exploitation activity in the region. The contamination of As, Cu, and Zn was controlled by minerals such as iron oxides and hydroxides (hematite, magnetite, and mainly goethite), manganese oxides, and sulfide-rich minerals. The As-bearing sediments of the region characterize one of the most As contaminated area of Brazil. Their main source is associated with gold exploration in the last three centuries.