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(T/MF177) Environmental impact of abandoned metal mines on stream water quality. Queralt, Ignasi1, Pujals, Ignacio2, Barreiros, Alexandra3, Bordalo, Manuela3, 1 2 3 ABSTRACT- Water pollution associated with drainage from abandoned mines is a worldwide increasing concern with environmental, recreational and industrial implications. From mines abandoned during last 20 years a set of growing legal regulations imply the environmental rehabilitation of mining sites after ceasing activity. However, discharges from mines abandoned before this time may continue to cause pollution. With the closure of most of the metal mines, the pumping of minewater ceased, resulting in the recovery of ground water levels within the mineshafts. Minerals in the rocks (sulphides, oxides, carbonates...) are dissolved in mine waters giving as consequence a noticeable concentration of metals. The Aran Valley (Central Pyrenees, Spain) was during hundred years an important mining district, mainly for zinc and lead recovery. Mining activity finished approximately at 1950. Therefore, tailings, galleries and some open pits remain abandoned and they are potential sources of metal pollution for the stream waters within the area. Two preliminary water sampling campaigns have been carried out within the area of the Zn-Pb Victoria mine (Aran Valley) in order to assess water quality in streamwaters, in mine galleries and in tailings. Sampling was carried out both in high-flow and low-flow conditions. Samples have been analysed by ICP-MS and TXRF techniques. Waters from shafts and galleries exhibit enormous differences in heavy metal content. Results evidence the complexity of the internal mining environment. Streamwaters at surface are more uniformly affected by mining. Results are compared with standard guidelines from WHO/OMS and nearest snowmelt streamwaters considered as the background level existing in the area. Despite the difficulties to establish a standard protocol for sampling strategy and a proper evaluation of the area, it is possible to distinguish high cadmium and nickel pollution and moderate pollution for Zn, Se, Ag, and Co. Key words: Heavy metals, mining, water, pollution |
