多嵌套空间尺度农田土壤重金属空间变异研究

Multi-nesting Spatial Scales of Soil Heavy Metals in Farmland

运用地统计学技术对棕壤土典型地块进行了重金属多尺度嵌套空间变异和结构来源分析。选取5种反映土壤污染水平的典型重金属元素铅(Pb)、镉(Cd)、汞(Hg)、铜(Cu)、铬(Cr)以及类重金属元素砷(As)进行采样检测。利用克里格法插值拟合,选择最优拟合模型,确定了合理采样间距。结合半方差和分维数分析,研究确定了合理采样尺度。采取主成分分析和半方差分析相结合的方法,确定土壤重金属来源,指导农业管理措施。研究表明,农田土壤重金属主要由成土母质、降水灌溉和农药施肥构成。中等尺度符合半方差模型拟合,变程的范围从319 m到752 m不等。其中球面模型更适合土壤重金属空间分布拟合描述。

Multi-nesting spatial variability and source analysis of statistical technology were applied to the typical plots which consist of brunisolic soil. By means of the sample testing results on five elements of heavy metals： Pb, Cd, Hg, Cu, Cr, with As element, which could reflect the levels of the soil pollution, aforementioned geo-statistical analysis process was done. Optimal model was selected by kriging interpolation method. And then, the reasonable sampling spacing was well determined. Combined with semivariance and fractal dimension analysis, the reasonable sampling scale was obtained. The method combined PCA with semivariance analysis together to trace to the source was adopted forward to guide agricultural management measures. The results indicated that the origin of farmland soil heavy metal composition was composed of three main source formations, which were soil parent material, precipitation and irrigation, and pesticide application. Medium scale jibed with semivariance model fitting. The value of range varied from 319 m to 752 m. The spherical model was thought more suitable to describe space distribution of soil heavy metal.