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Avaliação do nível de contaminação nos sedimentos de cursos de água do Sistema Mineiro de Caveira (Grândola)
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Advisor(s)
Abstract(s)
RESUMO: O presente trabalho, inserido no Projeto GeoMatRe, visa o levantamento das condições mais atualizadas no que toca aos parâmetros físico-químicos numa mina de drenagem ácida. Uma situação crítica que ocorre na área mineira de Caveira, em Grândola, Portugal, abandonada desde a década de 60 do século passado. O objetivo passa por analisar as condições de contaminação de Elementos Potencialmente Tóxicos (EPT) nos sedimentos que ocorrem quer em fases móveis e dissolvidas na água intersticial dos sedimentos, quer em fases mais imóveis. Neste trabalho é realizada uma caracterização geral da área do sistema mineiro, verificando-se um nível de contaminação da área, através da análise do Índice de Geoacumulação (IGEO) e do Fator de Enriquecimento (FE), onde os elementos Cu, Pb, Zn, As e Hg demonstram ser os principais EPT’s na região, apresentando valores, em alguns dos casos, milhares de vezes acima dos estipulados pelas normas nacionais.
ABSTRACT: The following work is inserted in the GeoMatRe Project, in which the conditions of the most updated physical and chemical parameters of an Acid Mine Drainage are analysed. This study shows that the mining area of Caveira, in Grândola, Portugal, which was abandoned since the 60’s, presents a critical situation of contamination, with high levels of Potentially Toxic Elements (PTE) present in the whole mining area and its surroundings. It is intended, within the scope of the project, and through geochemical analysis, to observe the conditions of contamination by PTE in native sediments from the mine tailing, which occur either in mobile phases, dissolved in the interstitial water of the sediments, or in more immobile phases. With that in mind, preparation of methodologies for geochemical studies were carried out, namely Fusion for further analysis of the element’s total forms, and Partial Digestion with Aqua Regia, for quantification of the most easily extractable forms, which represent the most contaminating fraction. Ultimately, Inductively Coupled Plasma Optical mission Spectrometer (ICP-OES) was used to analyse and quantify the previously prepared samples. It is herein presented a general characterization of the mining system, through analysis and understanding of the Geo-accumulation Index (IGEO) and the Enrichment Factor (EF), tools that improve the visualization of the previously obtained data on the ICP-OES, demonstrating the content and chemical nature of the contaminating elements (As, Cu, Zn, Pb and Hg) as main PTE’s in the region, presenting values, in some cases, thousands of times higher than those stipulated by Nacional standards.
ABSTRACT: The following work is inserted in the GeoMatRe Project, in which the conditions of the most updated physical and chemical parameters of an Acid Mine Drainage are analysed. This study shows that the mining area of Caveira, in Grândola, Portugal, which was abandoned since the 60’s, presents a critical situation of contamination, with high levels of Potentially Toxic Elements (PTE) present in the whole mining area and its surroundings. It is intended, within the scope of the project, and through geochemical analysis, to observe the conditions of contamination by PTE in native sediments from the mine tailing, which occur either in mobile phases, dissolved in the interstitial water of the sediments, or in more immobile phases. With that in mind, preparation of methodologies for geochemical studies were carried out, namely Fusion for further analysis of the element’s total forms, and Partial Digestion with Aqua Regia, for quantification of the most easily extractable forms, which represent the most contaminating fraction. Ultimately, Inductively Coupled Plasma Optical mission Spectrometer (ICP-OES) was used to analyse and quantify the previously prepared samples. It is herein presented a general characterization of the mining system, through analysis and understanding of the Geo-accumulation Index (IGEO) and the Enrichment Factor (EF), tools that improve the visualization of the previously obtained data on the ICP-OES, demonstrating the content and chemical nature of the contaminating elements (As, Cu, Zn, Pb and Hg) as main PTE’s in the region, presenting values, in some cases, thousands of times higher than those stipulated by Nacional standards.
Description
Keywords
Mina de Caveira Sedimentos Meio ambiente Remediação Depósitos sulfuretos maciços Caveira Mine Sediments Environment Remediation Massive sulfide deposits
Citation
da Silva, R., Fonseca, R., Araújo, J.F., Silva, N. & Albuquerque, T. (2025). Avaliação do nível de contaminação nos sedimentos de cursos de água do Sistema Mineiro de Caveira (Grândola). In: Comunicações Geológicas, 2025, vol. 112, Fascículo Especial I, pp. 305-309. https://doi.org/10.34637/yhz0-1q26
Publisher
LNEG - Laboratório Nacional de Energia e Geologia