Mineralogy of the sediments of water dams affected by Acid Mine Drainage in the Spanish sector of the Iberian Pyrite Belt (SW Europe)
- P. Gomes 1
- T. Valente 1
- J. Grande 2
- M.A. Sequeira Braga 1
- M. Santisteban 1
- 1 Institute of Earth Sciences, Pole of the University of Minho
- 2 CIPIMS, University of Huelva
ISSN: 1576-5172
Year of publication: 2016
Issue Title: IX CONGRESO GEOLÓGICO DE ESPAÑA
Issue: 16
Pages: 131-134
Type: Article
More publications in: Geotemas (Madrid)
Abstract
The Iberian Pyrite Belt (IPB), in southwestern of Spain, allocates 23 reservoirs dams along its fluvial net-work, built for industrial, mining, agriculture and/or recreation. These dams are affected by acid main drainage (AMD), presenting different degrees of contamination. The weathering of sulphides, mainly in the mine waste dumps, promoted the release of pollutants, such a sulphate and metals, which suffer transport into the water dams. The present work doc-uments the mineralogy of different grain size fractions (<2 mm and <2 μm fractions) of the water dam’s sediments. The mineralogical results obtained by X-ray diffraction were combined with geochemical data, namely through determina-tion of accumulation factors for some toxic elements. The obtained results indicate that contamination of the sediments is regulated by many factors, such as mineralogical composition of fine fraction and the presence of sorption sites on specific mineral phases. Thus, iron oxyhydroxides and iron hydroxysulfates are important components of the clay min-eral fraction, controlling the retention of toxic elements, especially in the mining dams.