豫西典型工业区周边农田土壤重金属污染特征、生态风险与来源解析

Characteristics,Ecological Risks and Sources of Heavy Metal Pollution in Agricultural Soils Surrounding Typical Industrial Zone in West Henan

为探究豫西典型工业区(1个钢铁厂、6个工业园、5个冶炼厂)周边农田土壤重金属污染特征与生态风险,采集并测定研究区109个土壤样品中镉(Cd)、铅(Pb)、砷(As)、锌(Zn)、铜(Cu)、铬(Cr)和镍(Ni)的含量,运用一系列指数法、形态分析、主成分分析和聚类分析等方法进行了重金属元素空间分布特征分析、污染与生态风险评价、形态和来源解析。结果表明,研究区域农田土壤重金属的污染程度与累积效应密切相关,Pb的污染程度最高,且地累积效应最强。Cd、Pb和As为引起土壤环境风险的主要因子,其对综合潜在生态风险指数的贡献率分别达到了48.26%、18.81%、15.58%。Pb和Cd的有效态含量分别高达92.49%、79.54%;Zn的铁锰氧化物结合态和Cu的有机结合态占比相对其他重金属较高,分别为33.07%、24.25%;而Cr、Ni迁移转化生态风险相对较低,在土壤中的赋存形态主要为残渣态,占比分别为91.00%、64.63%。冶炼厂(S1、S3)与周围的冶炼厂(S2、S4)、钢铁厂SW和工业园(IP1、IP2、IP3)对研究区域西北片区农田土壤重金属Pb、Cd和Zn的综合潜在生态风险产生了协同影响。Zn、Pb、Cu主要来源于工业源(冶炼厂、钢铁厂等工业生产活动);Cd和As来源于工业源(冶炼厂)和农业源;Cr、Ni主要来源为自然源。此外,Zn、Pb、Cu、Cd容易受自然淋溶、成土过程和农业活动的影响,增加迁移转化的生态风险。

In order to investigate the characteristics and ecological risks of heavy metal pollution in agricultural soils around typical industrial areas(1 steel mill,6 industrial parks,5 smelters)in West Henan,109 soil samples were collected and measured for Zn,Cu,Cd,Pb,Cr,Ni and As,and a series of indexes,morphology,principal components and clustering methods were employed for the spatial distribution analysis of the heavy metals,evaluation of the contamination and ecological risks,and analysis of the morphology and sources.The results revealed that the degree of contamination and cumulative effects of heavy metals in agricultural soils in the study area were closely related,and Pb had the highest level of contamination and the strongest geo⁃cumulative effects.Cd,Pb and As were the main factors causing soil environmental risks,and their contributions to the composite potential ecological risk index reached 48.26%,18.81%and 15.58%,respectively.The content of Pb and Cd in the effective state was up to 92.49%and 79.54%,respectively.The proportions of Fe⁃Mn oxide bound state of Zn and organic bound state of Cu were higher than other heavy metals,with 33.07%and 24.25%,respectively.Whereas the ecological risk of the migration and transformation of Cr,Ni was relatively lower,and the accumulation form in the soil was dominated by the residual state,which accounted for 91.00%,64.63%.The smelters(S1,S3)and the surrounding smelters(S2,S4),steel mill SW and industrial parks(IP1,IP2,IP3)had a synergistic effect on the comprehensive potential ecological risk of heavy metals(Pb,Cd and Zn)in farmland soils in the northwest of the study area.Zn,Pb and Cu mainly came from industrial sources(smelters,iron and steel mills and other industrial production activities);Cd and As originated from industrial sources(smelters)and agricultural sources;and Cr and Ni mainly emerged from natural sources.In addition,Zn,Pb,Cu and Cd were susceptible to natural leaching,soil formation processes and agricultural activities,which increased the ecological risk of migration and transformation.