重庆某农业集中区土壤重金属污染评价与来源解析

Pollution assessment and source analysis of soil heavy metals in a concentrated distribution area of agricultural in Chongqing

土壤重金属污染问题日益突出,分析土壤重金属污染成因与来源对污染防治和风险管控具有重要的指导意义。选择重庆某农业土壤集中分布区域,综合采用地累积指数、污染负荷指数、相关分析、主成分分析和正定矩阵因子分析等多种方法,开展了土壤重金属污染特征分析、土壤重金属污染评价和重金属来源解析。结果表明,研究区土壤中Cd、Hg、As、Pb、Cr、Cu、Zn和Ni8种重金属元素平均含量均高于重庆市背景值。其中累积程度最高的重金属为Hg,其次为As和Cd,其平均含量分别为重庆市土壤背景值的54.70、3.03和1.50倍。地累积指数统计结果表明,研究区内土壤Hg和As污染程度较深且分布面积较广。污染负荷指数法评价结果表明,研究区土壤重金属以轻微污染和中度污染为主,研究区综合污染负荷指数(P_(zone))为1.76,整体上呈轻微污染。采用正定矩阵因子分析法对重金属来源进行定量解析,结果表明,研究区土壤中As和Pb的积累主要来自于工业活动和交通排放;土壤中Cr、Cu、Zn和Ni主要来源于自然地质背景;土壤Cd的积累与农业生产活动有关;区域Hg污染由汞矿开采引起。

The problem of soil heavy metal pollution is becoming increasingly serious.Identifying the sources of soil heavy metal pollution has important guiding roles for pollution prevention and risk management control.A concentrated distribution area of agricultural soils in Chongqing was selected to study the pollution characteristics and sources of heavy metals in soils by multiple methods including geo-accumulation index,pollution load index,correlation analysis,principal component analysis and positive matrix factorization.The results showed that the average concentrations of heavy metals(Cd,Hg,As,Pb,Cr,Cu,Zn and Ni)in the surface soil all exceeded the soil background value in Chongqing,showing different levels of enrichment.The highest cumulative element in surface soil was Hg,followed by As and Cd,and their average concentrations were 54.70,3.03,1.50 times of the soil background values of the Chongqing.The statistical results of the geo-accumulation index indicated that Hg and As were pollutants in the study area with a high pollution level.The evaluation results of the pollution load index method showed that the study area was slightly polluted as a whole,and the comprehensive pollution load index(P_(zone))of the study area was 1.76.The results of positive matrix factorization showed that the accumulation of As and Pb in the soil of the study area were mainly caused by industrial activities and traffic emissions,and Cr,Cu,Zn and Ni in the soils were mainly from natural geological background,and Cd in the soils was mainly caused by agricultural production activities,and Hg in the soils was mainly caused by mining of mercury ore.