Spatial variation and environmental indications of soil arsenic in Guangdong province

Total of 260 soil profiles were reported to investigate the arsenic spatial distribution and vertical variation.The arsenic geometric mean concentration of 10.4 mg·kg-1 was higher than that of China.An upper baseline concentration of 23.4 mg·kg-1 was estimated for surface soils.Arsenic spatial distributions presented the similar patterns that high arsenic concentration mainly located in limestone and sandshale areas,indicating that soil arsenic distribution was dependent on bedrock properties.From A-to C-horizon arsenic geometric mean concentrations had an increasing tendency of 10.4,10.7 to 11.3 mg·kg-1.This vertical variation may be related to the lower soil organic matter and soil degradation and erosion.Consequently,the soil arsenic export into surface and groundwater would reach 1040 t?a-1 in the study area.