Geostatistical, analysis of soil arsenic content in Taiwan

A combined geostatistical and computergraphic approach was developed for illustrating the soil Arsenic map of Taiwan. Data were collected from the Environmental Protection Administration's study targeting agricultural soils in Taiwan. The range and arithmetic mean of the As contents in the surface soils (0 to 15 cm) of the study samples are as follows: 0.01 to 16.16, 5.65 (mg/kg dry soil). Variograms (Semivariograms) indicated spatial correlation at distances up to 195.0 ion. The data exhibited some anisotropy, but this had little effect on kriging. An exponential variogram model was fitted using least squares and used to krige a grid covering Taiwan. Soils southwest of Taiwan tended to contain higher levels of As than average. The map will be useful in future research to determine the geographic distribution of regional patterns of plants and groundwater As content, the relationship between As and parent soil material, and correlation with of occurrence of blackfoot disease.