禹城地区土壤铅含量空间分布的指示克里格估值

Indicator Kriging of spatial distribution of soil Pb content in Yucheng city

以鲁西北禹城地区土壤重金属Pb含量为例,针对其存在特异值与偏态分布的特点,利用指示克里格法研究了土壤Pb含量小于特定阈值的条件概率分布,分析了该地区土壤Pb含量的空间分布特征,并对普通克里格和指示克里格的估值效果进行交叉验证。结果表明:研究区土壤Pb含量总体较低,未超过国家标准的限值,但不同部位土壤Pb含量差异较大;普通克里格法和指示克里格法形成的土壤Pb含量空间分布格局相似,但普通克里格法的平滑效果强于指示克里格法;研究区域土壤环境质量总体良好,Pb含量高值区主要集中在各乡镇驻地附近的农田;指示克里格对土壤Pb含量空间估值的精度优于普通克里格,指示克里格法更适用于原始数据呈非正态分布且特异值对估值结果有较大影响的土壤属性。本研究结果为该地区土壤环境质量评价和重金属污染防控提供科学依据。

Considering the outliers and skew distribution of heavy metal Pb content in Yucheng soils,indcator kriging method was introduced to study the conditional probability of soil Pb content less than some cutoffs.The spatial variability of soil Pb content across the study area was analyzed,and the estimation precision was compared and cross-validated for ordinary kriging(OK) and indicator kriging(IK) methods.Results indicated that soil Pb content in Yucheng city is generally low and less than the limit value of national standards,while the Pb content varies greatly at various locations.The Pb spatial dstribution generated by OK method shows the similar pattern to that generated by IK method,and the former is smoother than the latter.The soil environmental quality of Yucheng city is totally in favorable condition,and the regions of high value of Pb content are largely situated in the field nearby the town residents.The Pb spatial estimation precision of IK method is superior to that of OK method,and the IK method is more applicable to soil properties with innormal distribution and outliers than OK method.The research results provide scientific reference to environmental quality assessment and prevention of soil heavy metal contamination for Yucheng city.