DEGEO - Departamento de Geologia

URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/8

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2005 - 200912010 - 20161

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Autor: search.filters.author.Windmoller, Cláudia CarvalhinhoTem arquivos: Sim

Resultados da Pesquisa

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    Quantification of methylmercury and geochemistry of mercury in sediments from a contaminated area of Descoberto (MG), Brazil.
    (2016) Mendes, Louise Aparecida; Lena, Jorge Carvalho de; Valle, Cláudia Magalhães do; Fleming, Peter Marshall; Windmoller, Cláudia Carvalhinho
    In 2002, metallic Hg was found buried in a rural area of Descoberto city, Brazil. The origin of the Hg was a gold mining explotation plant established nearly one century ago. Although a number of studies have been conducted in order to assess the contamination of the area, none of them investigated the presence of methylated Hg in the hydric system. In this work methylmercury (CH3Hgþ) was determined using gas chromatography-pyrolysis-atomic fluorescence detection (CG-pyro-AFS) in material from rain sedimentation boxes and stream sediments near the contaminated area. Total Hg concentration (HgT) along with the chemical speciation by thermo-desorption were performed. HgT in material from the sedimentation boxes was found to be very high, up to 41,580 mg kg 1, even in the rainy season, when in general HgT were much lower than in dry season. The samples from the Grama and Rico streams show a range of HgT from 5.8 to 266 mg kg 1. The thermo-desorption analysis showed predominance of Hg2þ, possibly linked to organic sulfur, suggested by a good positive correlation between Hg2þ, HgT, organic mater (OM) and total S. The CH3Hgþ concentration in stream sediment samples ranged from <0.07 to 1.87 mg kg 1 and in the samples of sedimentation boxes the concentrations were 1.33 and 8.0 mg kg 1 during dry season. The sample with the highest percentage of HgT as Hg2þ (98%) presented also the highest percentage of CH3Hgþ (0.7%). These are high values, showing that care should be taken to avoid the transport of this material to the hydrological system. Further studies on the transfer through the food chain would be very important.
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    Quantification and speciation of mercury in soils from the Tripuí Ecological Station, Minas Gerais, Brazil.
    (2005) Palmieri, Helena Eugênia Leonhardt; Nalini Júnior, Hermínio Arias; Leonel, Liliam Viana; Windmoller, Cláudia Carvalhinho; Santos, Regis Costa; Brito, Walter de
    Contents of total mercury, organic carbon, total sulfur, iron, aluminum and grain size and clay mineralogy were used along with Pearson’s correlation and Hg thermal desorption technique to investigate the presence, distribution and binding behavior of Hg in soils from three depths from the Tripuı´ Ecological Station, located near Ouro Preto, Minas Gerais State, Brazil. The soils studied had predominantly medium and fine sand texture (0.59–0.062 mm), acid character and Hg contents ranging from 0.09 to 1.23 Ag/g. The granulometric distribution revealed that Hg is associated with coarse sand (2–0.59 mm) and silt and clay (b0.062 mm) and presents similar Hg concentrations in both fractions. Mercury distribution in soil profiles showed that Hg was homogeneously distributed throughout the depths at most sites. Hg thermal desorption curves show that mercury occurs not only as Hg2+ predominantly bound to organic components in most of the samples, but also in the form of cinnabar in some. Pearson’s correlation confirmed that mercury is associated with organic matter and sulfur and possibly with sulfur-bearing organic matter in most samples.