and possibly from leaching from the surrounding farm lands as
well. The detection of ASA and the absence of ROX, which is more
stable than ASA, in the environmental matrices is consistent with
the fact that ASA had long been used as the feed additive in
large-scale swine farms in Guangdong province (Wang et al.,
2006). The widespread occurrence of ASA in the environmental
matrices surrounding the CAFOs proves that animal wastes from
the swine farms are an important source of arsenic pollution in
the CAFO zone.