基于GIS的农田土壤重金属空间插值分析及污染评价——以江苏省南通市为例

GIS-based Spatial Interpolation and Pollution Appraisal of Heavy Metal in Cropland Soil——A Case Study of Nantong in Jiangsu Province

以江苏省南通市土壤重金属污染情况调查的资料数据为基础,比较不同的空间插值方法后选用合适的模型进行空间插值计算,并根据插值结果对南通市农田土壤重金属空间分布和污染现状进行分析和评价.研究结果表明,样本数据的离散程度会影响空间插值的结果,对离散程度大的数据,应根据实际应用进行转换以降低其离散程度.南通市五种重金属超过自然背景值的面积比例分别为:Hg 2.75%;As 23.02%;Pb 68.24%;Cd 0.01%;Cr 5.59%.南通市各市县Pb的污染指数均超过1,海门市、南通市区和启东市的As污染指数均超过1.南通市区、海门市和启东市的综合污染指数处于警戒限,通州市的综合污染指数接近警戒限.

In this case study, data came from the survey on heavy metal poUution in Nantong, Jiangsu province. After comparing various methods of spatial interpolation, the paper adopted an appropriate model to conduct the spatial interpolation, from which the analysis of spatial distribution and the pollution appraisal of heavy mental in cropland soft in Nantong were derived. The findings indicate that dispersion of the sample data can affect the result of spatial interpolation. The widely dispersed data should be transformed to lower their dispersion degree. The area proportions of heavy metals Fig, As, Pb, Cd, and Cr were 2.75 %, 23.02 %, 68.24 %, 0.01%, and 5.59 % respectively. The Pb pollution index in every city and county in Nantong surpassed 1. The As pollution index of Halmen, Nantong and Qidong surpassed 1. The combined pollution index of Nantong, Haimen and Qidong were being at the warning limit. The combined pollution index of Tongzhou was approaching the warning limit.