ABSTRACT
Mobilisation of As in contaminated niches occurs through a complex set of conditions and biogeochemical processes. These include the interplay of hydro-geo-bio-chemical processes and human interactions (Kar et al., 2010; Smedley and Kinniburgh, 2013). Owing to spatial variations in hydrogeochemical and microbiological properties, the As release mechanism may vary with location. In most of the contaminated aquifers, elevated As concentrations typically result from the mobilisation and transport of this metalloid under natural conditions. Although the release of As due to weathering and the mobilisation of As-bearing minerals or from geothermal sources over millions of years seems to contribute a large part of the contamination; lower amounts are of anthropogenic origin, for example, smelting, mining and agricultural activities (Muller et al., 2007; Pepi et al., 2007). The latter
activities may directly add various As compounds into the environment or cause/exacerbate mobilisation (Smedley and Kinniburgh, 2013).
