基于最适空间插值的崇州市典型农田土壤重金属污染特征分析与评价

Heavy metal pollution characteristics and soil quality assessment of typical farmland Soils in Chongzhou City of Sichuan province

以崇州市典型农田为研究对象,运用地统计学分析方法和最适空间插值理论模型,调查与分析了研究区土壤重金属污染状况与特征,并运用加权内梅罗指数评价进行了土壤环境质量评价。结果表明:(1)研究区农田土壤As、Cd、Cr、Cu、Hg、Ni、Pb、Zn平均值均超过了四川土壤背景值(1990年),其中Cd最为严重,Cd平均值(0.42 mg·kg-1)达到背景值的5.32倍;(2)对照《土壤环境质量农用地土壤污染风险管控标准(试行)》(GB15618-2018)中农用地的风险筛选值,研究区农田土壤存在As、Cd污染风险,超过污染风险筛选值的样品数分别达到了样品总量的4.0%、42.0%,但是,8项重金属均未超过风险管制值,说明研究区土壤重金属状况对农产品质量安全、农作物生长或土壤生态环境存在风险;(3)经过变异函数拟合,研究区农田土壤As、Cd的最适模型分别为指数模型、高斯模型,经过空间插值分析和质量评价表明,研究区大部分区域处于警戒线和轻度污染等级风险水平。

Selecting the typical farmland in Chongzhou City of Sichuan Province,we used the geo-statistical analysis method and optimal spatial interpolation theory model to investigate the soil heavy metal pollution,and assessed the soil environmental quality by weighted Nemero index.The results showed that:(1)The average values of As,Cd,Cr,Cu,Hg,Ni,Pb and Zn in the farmland soils exceeded the soil background value of Sichuan(1990),and the Cd content of 0.42 mg·kg-1 was 5.32 times greater than the background value;(2)Compared with the risk screening value of agricultural land in the Soil Environmental Quality Agricultural Pollution Risk Control Standard(Trial)(GB15618-2018),the farmland soils were in risks of As and Cd pollutions,and the samples exceeding the pollution risk screening values accounted for 4.0%and 42.0%of the total samples,respectively,while the other eight heavy metals contents were in accordance with the risk control standard values,indicating the area was with a friendly environment for safe agricultural product quality and crop growth;(3)By fitting the variogram,the optimal models of As and Cd in the farmland soils were exponential model and Gaussian model,respectively.After spatial interpolation analysis and quality evaluation,most study areas were at the warning levels or with risks of light pollution levels.