新疆盐渍化区土壤盐分离子的空间变异特征

Spatial Variability of Soil Saltions in Xinjiang Salinization Region

土壤中盐分含量与空间分布是了解多孔介质中水盐运移规律并进而因地制宜提出盐渍土改良措施的关键。利用地统计学,结合地理信息系统（GIS）,在面积约为2 000 km2的新疆典型盐渍化区渭干河流域布设了土壤取样点43个,测定了土壤表层（0～30 cm）盐分及其组成（Ca^2＋、Mg^2＋、K^＋、Na^＋、SO4^2-、Cl^-、HCO3^-）的空间变异性规律。结果表明：Ca^2＋、HCO3^-为正态分布,其余盐分离子符合对数正态分布;半方差分析得出总盐分符合球状模型,Mg^2＋、K^＋、Na^＋、Cl^-、SO4^2-符合指数模型,Ca^2＋符合高斯模型,而HCO3-则是纯块金效应;盐分离子的变程在14.3 km～64.1 km之间;盐分离子均表现为中等强度的空间自相关,但程度有所差异。用Kriging插值法对未测点的盐分离子进行最优估计,绘制含量分布图,从而可以更直观的反映研究区土壤盐分离子的空间变异特征。

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 forty-three samples and analyzed the spatial variability of soil salts（total salts, Ca^2＋ , Mg^2＋ , K^＋ , Na^＋ , SO4^2- , Cl^- , HCO3^- ）in topsoil （0~30cm）from about 2 000 km^2 of typical saline soil of Weigan drainage area in Xinjiang. The results indicated that Ca^2＋ and HCO3^- 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, Mg^2＋ , K^＋ , Na^＋ , SO4^2- , Cl^- were best described by exponential model, Ca^2＋ was fitted well using the Gauss model,and HCO3^- showed the pure nugget effect The ranges of soil salinities were 14.3 km 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 HCO3^- , 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.