运城市村级农业土壤重金属的空间分布与原因分析

摘要

Heavy metal concentrations including Cu, Zn, Cr, Cd, Pb, Ni, As, Hg in agricultural soil of Nanxue village, Yuncheng city were investigated to analyze its spatial distribution and pollution sources. Compared with the provided standards in the level 2 of China Soil Environment Quality Standards, the percentages of soil Hg and Ni contents were 16. 50% and 12. 62% higher respectively, while the soil Cd, Pb, As contents were below the thresholds of the soils quality standards. Ac-cording to the single pollution index evaluation results, the major pollutant was Hg, and its pollution index was 1. 58 which reached a slight pollution level. The single pollution index of other heavy metals were less than 1, which were safe. According to the Nemerow integrated pollution index evaluation, 61. 65% of the heavy metal contents in agricultural soils was in a safe level, 18. 45% was in the cordon, 15. 53% was in moderate or severe pollution, and only a little soil was in light pollution. The nugget effects of soil Zn, Cr, Ni and As contents were between 25% and 75%, which indicated that the spatial distribu-tion of soil Zn, Cr, Ni and As contents were influenced by pesticides, fertilizer and material factors together. Meanwhile, the nugget effects of soil Cu, Cd, Pb and Hg contents were larger than 75% which indicated that the spatial distribution of soil Cu, Cd, Pb and Hg contents were primarily controlled by manure, sewage, automobile exhaust and residents living. Differ-ent ways of agricultural production among different regions can cause the significant difference of spatial distribution of heavy metal concentrations, which is of great significance on guiding the rational allocation of resource, scientific management of ag-ricultural production and crops security.%通过检测运城市南薛村农业土壤8种重金属( Cu、 Zn、 Cr、 Cd、 Pb、 Ni、 As、 Hg)含量,分析研究区内重金属空间分布特征和原因。与国家土壤环境标准的二级标准相比, Hg 和 Ni 的超标率分别为16．50%和12．62%, Cd、 Pb、 As均未超标。按单项污染指数进行评价,主要污染物是Hg,污染指数为1．58,处于轻度污染级别,其余重金属的单项污染指数均小于1,处在安全域内。按内梅罗综合污染指数评价,61．65%的农业土壤重金属污染程度处于安全水平,18．45%的土壤处在警戒线上,15．53%的土壤为中度污染和严重污染,只有个别土壤属轻污染。 Zn、 Cr、 Ni和As的块金效应介于25%~75%之间,同时受农药、化肥和母质因素的影响； Cu、Cd、 Pb和Hg的块金效应大于75%,分别受粪肥、污水、汽车尾气和居民生活的影响。8种重金属含量空间分布差异显著,主要原因是不同地块间的生产方式不同,该研究对于试验区农业资源的合理配置、农业生产的科学管理和农产品的安全生产具有重要的指导意义。