ABSTRACT
The hydrosphere is often seen as the most active medium for As transfer to man. Evidence derives from numerous incidents, mainly in the Americas and Asia, namely Argentina, Bangladesh, Chile, China, India, México, Mongolia, Taiwan, the USA, and West Bengal, from where cases of human intoxication through water have been reported (e.g., Bundschuh et al. 2008a, b; Chappell et al. 2003). From a toxicological perspective, the inorganic reduced As(III) is more toxic than the oxidized As(V) (c 2), making anoxic (ground)waters more risky than aerobic surface water. Arsenic occurs as arsenate in most surface and drinking waters, due to the presence of sufficient dissolved oxygen (c 1). In anaerobic waters, arsenides can occur (Goyer et al. 1999; Irgolic 1994). Arsenic mobilization and translocation to waters follow various paths:
a. Direct transport by surface and percolation water is the main factor for the transport of suspended and dissolved solids. This includes the As mobilization from primary ores and mining-related activities. Inadequate control of tailing dams, combined with high precipitation can cause significant losses of waste material into surface waters.
