ABSTRACT
The establishment of vegetation on pyrite-bearing mine wastes is often problematic due to the tendency of these materials to rapidly oxidize and acidify on exposure to air and water (Johnson et al., 1994). Although the acidification of growing media and the ensuing onset of acid mine drainage (AMD) is a problem associated most commonly with pyrite-rich colliery spoil (Caruccio, 1975), these processes also impact mine wastes derived from gold and base-metal sulfide deposits (Harries, 1997; Table 10.1). In addition to low pH and high bioavailability of phytotoxic met als, metalliferous wastes typically exhibit multiple nutrient deficiencies and poor physical growing conditions, which may further hinder plant establishment (Bradshaw and Chadwick, 1980). An approach commonly used to establish vegetation on metalliferous mine-wastes is to cap them with composite covers of clay, rock, and soil which serve to physically isolate contaminants and to provide growing media for plants (Table 10.1).
