Acid Rock Drainage samples from an abandoned Zn-Pb-Ag mine investigated by XAS

In the aqueous environment of abandoned ore mines, iron sulphide ore crystals play a key role in the sulphide oxidation and water mineralization process occurring there. Highly miner-alised, red-coloured solutions are formed by weathering of ore particles which causes acid rock drainage (ARD). Major cationic components (>1 g/l) of the ARD solution under study were Zn, Fe, Mg, Al, and Mn. Important minor components were toxic heavy metals, e.g. As, Cu, Pb, and Cd. This XAS investigation deals with the in-situ characterisation of the near-order surrounding of As in ARD solutions containing colloidal particles as well as with the determination of the particle mineralogy. The atomic surrounding of Fe and As in ARD samples is compared to those found in model compounds. The presented study is an example for the broad applicability of X-ray absorption spectroscopy (XAS) techniques to environmental research.