“…The weathering of such materials may cause contamination of ground-and surface-waters by acidity, dissolved metals and salinity. Microbial processes play an important role in the weathering of sulfidic rocks and minerals, causing acid mine drainage (AMD) (Colmer and Hinkle, 1947;Silverman and Ehrlich, 1964;Singer and Stumm, 1970;Karavaiko et al, 1972;Nordstrom, 1982;Harris and Ritchie, 1983;Moses et al, 1987;Watzlaf, 1988;Ehrlich, 1990;Kleinman et al, 1991;Bosecker, 1994;Evangelou, 1995;Schippers et al, 1995;Yu, 1996;Gray, 1997;Johnson and Bridge, 1997;Kwong et al, 1997;Schüring et al, 1997;Geldenhuis and Bell, 1998;Mills et al, 1998;Booth and Bertsch, 1999;Edwards et al, 2000;Iribar et al, 2000).…”