ABSTRACT
According to a survey conducted in 2006, more than 60 hectares of soils located in Guandu Plain, Taipei, were contaminated by arsenic (As) (≥60 mg/kg). The maximum As concentration in topsoil (0-15 cm) reached as high as 500 mg/kg. The contamination source of As in this area may came from the soil parent material, andesite, and the hot spring water of Thermal Valley located around 5 km northeast away from Guandu Plain. The hot spring water flowed out and mixed with the stream water which was used as irrigation water for rice growing in the As-contaminated area of the Guandu Plain.
