Geostatistical, analysis of soil arsenic content in Taiwan

A combined geostatistical and computergraphic approach was developed for il lustrating the soil Arsenic map of Taiwan. Data were collected from the Env ironmental Protection Administration's study targeting agricultural soils i n Taiwan. The range and arithmetic mean of the As contents in the surface s oils (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 us ing 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 r egional patterns of plants and groundwater As content, the relationship bet ween As and parent soil material, and correlation with of occurrence of bla ckfoot disease.