ABSTRACT
Groundwater samples were collected at different depths (60 m-300 m) from Beimen, an area of Chianan Plain, southwestern Taiwan (Figure 1), which is known for endemic blackfoot disease. Groundwater temperature, pH, EhS.H.E. (relative to
1 INTRODUCTION
In a dissolved state, As occurs mainly in the form of the inorganic species i.e. arsenite [As(III)] and arsenate [As(V)], and the former species, which is more bioavailable, is usually more toxic than As(V) (Lievremont et al., 2009). Oxidation of As(III) leads to the formation of the less bioavailable and less toxic As(V), which can be either precipitated or adsorbed by metal (hydr)oxides (Silver & Phung, 2005). As(III)-oxidizing bacteria can thus contribute to the natural remediation processes, as observed in different contaminated aquifers (Lievremont et al., 2009). The role of arsenite oxidizers in natural attenuation of arsenic pollution necessitates studies on their abundances and diversity in arsenic-contaminated aquifers.
