Speciation and quantification of Hg in sediments contaminated by artisanal gold mining in the Gualaxo do Norte River, Minas Gerais, SE, Brazil

The Iron Quadrangle in SE Brazil was, in the eighteenth century, one of the most important Au producing regions of Brazil. In this region, gold is produced, even today, by artisanal methods that use Hg to increase the extraction efficiency with no control of Hg release to water systems and the atmos...

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Bibliographic Details
Published in:	Environmental monitoring and assessment Vol. 190; no. 1; pp. 49 - 11
Main Authors:	da Penha Rhodes, Valdilene, de Lena, Jorge Carvalho, Santolin, Camila Vidal Alves, da Silva Pinto, Thais, Mendes, Louise Aparecida, Windmöller, Cláudia Carvalhinho
Format:	Journal Article
Language:	English
Published:	Cham Springer International Publishing 01-01-2018 Springer Nature B.V
Subjects:	Atmosphere Atmospheric Protection/Air Quality Control/Air Pollution Bioaccumulation Biogeochemical cycle Biogeochemical cycles Biogeochemistry Brazil Chromatography Contaminated sediments Correlation analysis Detection Dimethylmercury Earth and Environmental Science Ecology Ecotoxicology Environment Environmental Management Environmental Monitoring Environmental science Fluorescence Gas chromatography Geologic Sediments - chemistry Gold Gold - analysis Gold mines & mining Interactions Iron Iron - analysis Manganese Manganese - analysis Mercury Mercury (metal) Mercury - analysis Methyl mercury Methylation Methylmercury Methylmercury Compounds - analysis Mining Monitoring/Environmental Analysis Principal components analysis Pyrolysis River basins Rivers Rivers - chemistry Sediment Sediment pollution Sediments Speciation Statistical analysis Statistical methods Water - analysis Water Pollutants, Chemical - analysis Water springs Brazil Gualaxo do Norte River Small-scale gold mining activities Sediment Mercury speciation Doce River basin
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Summary:	The Iron Quadrangle in SE Brazil was, in the eighteenth century, one of the most important Au producing regions of Brazil. In this region, gold is produced, even today, by artisanal methods that use Hg to increase the extraction efficiency with no control of Hg release to water systems and the atmosphere. In this context, the Gualaxo do Norte River is of particular interest; its springs are located in the Doce River basin, an important Brazilian basin that supplies water for 3.5 million people. The main goal of this work was to quantify and speciate the Hg in the sediments of the Gualaxo do Norte River using a direct mercury analyzer and gas chromatography-pyrolysis-atomic fluorescence detection system. Statistical analyses consisted of principal component analysis, aiming to assess interactions among elements and species and to group the variables in factors affecting the properties of sediment. The results show that total Hg (THg) and methylmercury (CH 3 Hg + ) concentrations in samples ranged from 209 to 1207 μg kg −1 and from 0.07 to 1.00 μg kg −1 , respectively (methylation percentages from 0.01 to 0.27%). Thermal desorption analysis showed that mercury is mainly present in the oxidized form, and correlation analyses pointed to a relationship between THg and MnO, indicating that manganese can oxidize and/or adsorb Hg. Together, MO and CH 3 Hg + are important parameters in the third principal component, indicating the influence of OM on the methylation process. This first investigation on Hg methylation in this small-scale gold mining area points to the possibility of Hg bioaccumulation and to the need of better understanding the biogeochemical cycle of Hg in this area. Samples were collected in 2012, prior to the 2015 Fundão Dam disaster. The results are also a record of the characteristics of the sediment prior to that event.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0167-6369 1573-2959
DOI:	10.1007/s10661-017-6394-4