山西省天镇县设施菜地土壤重金属污染评价及其源解析

Pollution evaluation and source analysis of heavy metals in facility vegetable land soils of Tianzhen County of Shanxi Province

近年来农村耕地土壤重金属污染屡有报道,其中设施菜地具有复种指数高、施肥量大、栽培环境封闭等特点,易造成重金属在土壤中累积。为解析山西省天镇县设施菜地土壤重金属污染现状及重金属来源途径,采用单因子污染指数、综合污染指数以及潜在生态危害指数对天镇县设施蔬菜地土壤中Cu、Pb、Zn、Cr、Cd、Ni、Hg、As共8种重金属元素的污染状况进行评价,并结合主成分分析探讨其来源。结果表明,以《温室蔬菜产地环境质量评价标准》(HJ 333—2006)为依据,天镇县设施菜地Cu、Pb、Zn、Cr、Hg、As、Ni的单因子污染指数平均值不超过1.0,污染等级均为清洁。但所有土样的Cd平均值为0.46 mg/kg,最大值达0.96 mg/kg,单因子污染指数平均值为1.54,属于轻度污染。8种重金属元素综合污染指数平均值为1.19,属于轻度污染。以山西省土壤元素背景值为评价标准,Cu、Pb、Zn、Cr、Ni、As潜在生态危害指数平均值小于40,属于轻微生态危害。Hg潜在生态危害指数平均值为63.61,属于中等生态危害。Cd潜在生态危害指数平均值为135.75,属于强生态危害。多元素潜在生态危害指数平均值为221.94,属于中等生态危害。源解析结果表明,Cu、Pb和Ni来源于成土母质释放、矿山开采、交通运输和农业活动,Cr、Cd来源于成土母质释放和农业活动,Zn、Hg来源于矿山开采、农业活动和原煤燃烧,As来源于成土母质释放、大气沉降和化肥施用。天镇县设施菜地土壤中Cd和Hg存在生态环境风险,应该引起重视。

In recent years,heavy metal pollution of farmland soil has occurred frequently.Facility vegetable land has the characteristics of high multiple cropping index,large amount of fertilizer and closed cultivation environment,easy to cause heavy metal accumulation in the soil.To study the pollution level and source of heavy metals in the facility vegetable land soils of Tianzhen County of Shanxi Province,the experiment used single factor pollution index,comprehensive pollution index and potential ecological hazard index methods to analyze Cu,Pb,Zn,Cr,Cd,Ni,Hg and As in soils,and analysed their source according to principal component analysis.The results showed that,based on the“Environmental quality evaluation standards for farmland of greenhouse vegetables production”(HJ 333-2006),the average single factor pollution indexes of Cu,Pb,Zn,Cr,Hg,As and Ni were less than or equal to 1.0,and the pollution level were clean.In all sampling points,the average value of Cd was 0.46 mg/kg,with the highest value of 0.96 mg/kg.The average single factor pollution indexes of Cd was 1.54,which was slightly polluted.The average comprehensive pollution index of 8 elements was 1.19,which was slightly polluted.According to the evaluation standard of the soil element background value in Shanxi Province,the average value of the potential hazard indexes of Cu,Pb,Zn,Cr,Ni and As were less than 40,which was a slight ecological hazard.The average value of Hg potential hazard index was 63.61,which was a medium ecological hazard.The average value of Cd potential hazard index was 135.75,which was a strong ecological hazard.The average value of the multi-element ecological potential hazard index was 221.94,which was a medium ecological hazard.Through source analysis,Cu,Pb and Ni were derived from parent material,mining,transportation and agricultural activities.Cr and Cd were derived from parent material and agricultural activities.Zn and Hg sourced in mining,agricultural activities and raw coal combustion.As came from parent material,atmospheric deposition and chemical fertilizer application.In short,Cd and Hg had ecological environmental risk in facility vegetable land soils of Tianzhen County,which should be taken seriously.