Application of GIS and Geostatistics to Characterize Spatial Variation of Soil Fluoride on Hang-Jia-Hu Plain, China

Spatial variability of soil fluoride in the plough layer 0~20cm of paddy soil from Hang-Jia-Hu Plain of Zhejiang Province in China was studied using geostatistical analysis and GIS technique. The results of Semivariograms analysis showed that two forms of soil fluoride were correlated in a given spatial range, and total fluoride (T-F) was controlled by intrinsic factors of parent material, relief and soil type, whereas water-soluble fluoride (Ws-F) was greatly affected by extrinsic factors such as fertilization and soil management. Kriging method was applied to estimate the unobserved points and their distribution maps were obtained, which indicated that the concentrations of soil T-F and Ws-F had a close relationship with parent material, pH value, organic matter, cation exchange capacity content and soil texture. The main contents distribution of T-F and Ws-F were 200~300mg kg , 0.5~1.0mg kg in the studied area, respectively. And what is more, the range of T-F contents in soil was as low as less than 100 mg kg in Yu-hang area accounting for 23.7% area scale. The range of fluoride contents in the soils from central and eastern parts of Hang-Jia-Hu Plain was higher than that from the western part. The accumulation of fluoride contents in soil was lower in the whole studied area suggesting that local fluoride epidemic such as dental caries due to lack of fluoride should be prevented by using fluoridecontaining toothpaste.