A geostatistical approach for mercury spatial patterns assessment in sediments in an old mining region: The Caveira Mine case study,  Portugal

Mota, Natália; Fonseca, Rita; Araújo, Joana; Isabel Margarida Horta Ribeiro Antunes; Valente, Teresa; Barroso, Ana; Araújo, Alexandre; Albuquerque, Maria Teresa

http://hdl.handle.net/10400.11/10118

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Authors

Mota, Natália

Fonseca, Rita

Araújo, Joana

Isabel Margarida Horta Ribeiro Antunes

Valente, Teresa

Barroso, Ana

Araújo, Alexandre

Albuquerque, Maria Teresa

Abstract(s)

Mercury pollution is significant in many former mining communities worldwide, including in developing countries. Anthropic contributions to environmental Hg pollution are mostly connected to fuel fossil emissions, industrial and mining activities. Among mining operations, gold exploration contributes to the highest Hg contamination rates, given the processes, widely used in the past, of mixing Hg with the gold containing ore, to separate this metal from the bulk impurities. This study, as part of the GeoMaTre project, an ongoing collaborative network (2021-2024) between the Polytechnic Institute of Castelo Branco and the University of Évora, Portugal, aimed to evaluate the potential risk of mercury pollution in stream sediments in the Caveira area, an abandoned Cu, Pb, Zn, Ag, and Au mine, included in the Iberian Pyrite Belt, at South Portugal. This mine corresponds to a Gossan developed on pyrite mineralization, with high gold and silver content at the official beginning of its exploitation, in 1863, having exhausted the reserves in these precious metals in the 1920s. Until the date of its abandonment (1966) the exploitation focused on the remaining metals (Cu, Pb, Zn) and S. Currently, the surrounding area of Caveira mine is essentially composed of areas of waste accumulation, from mining activity, with little or no vegetation. Thirty-three sediment samples were collected from within 0 to 10 cm depth, in a grid of 1Km x 1Km. Hg was determined in samples preserved at about 4ºC at the time of collection, through a mercury analyzer (NIC MA 3000) based on thermal decomposition, gold amalgamation, and cold vapor atomic absorption spectroscopy detection.

Keywords

Caveira mine Mercury Sequential Gaussian sSimulation G clustering Probability map

URI

http://hdl.handle.net/10400.11/10118

Citation

MOTA, Natália [et al.] (2022) - A geostatistical approach for mercury spatial patterns assessment in sediments in an old mining region: The Caveira Mine case study, Portugal. In 14th International Conference on Geostatistics for Environmental Applications (geoENV2022), Parma, 2022 - Ecology, Natural, Resources: Proceedings. Parma : Università. P. 2-3.