Spatial Variability of Soil Saltions in Xinjiang Salinization Region

The quantity and distribution of soil salinities is a major component in the study of chemical transportation in the vadose zone and groundwater system.Geostatistics combined with GIS was applied to collect 43 samples and analyzed the spatial variability of soil salts(total salts,Ca2+,Mg2+,K+,Na+,SO2-4,Cl-,HCO-3) in top soil(0-30 cm) from about 2 000 km2 of typical saline soil of Weigan drainage area in Xinjiang.The results indicated that Ca2+ and HCO-3 showed a normal distribution,the others with a lognormal distribution.The chemical analysis of semivariograms indicated that total salts was best described by spherical model,Mg2+,K+,Na+,SO2-4,Cl-were best described by exponential model,Ca2+ as fitted well using the Gauss model,and HCO-3 showed the pure nugget effect.The ranges of soil salinities were from 14.3 to 64.1 km.The spatial variability of all soil salinity ions were mainly produced by structural factors and random factors.The results also showed that except of HCO-3,the spatial correlation of other tested parameters,were moderately dependent,but their spatial heterogeneity degree was different.The Kriging method was applied to estimate the unobserved points and then the precise contour maps were obtained.By this way,the spatial variability of soil salinity ions could be reflected directly.