天津近郊农田土壤重金属风险评价及空间主成分分析

Ecological risk assessment and principal component analysis of heavy metals in suburban farmland soils of Tianjin

以天津市近郊西青区主要农产品生产基地表层土壤(0—20 cm)作为研究对象,分析了V、Cr、Ni、Cu、Zn、As、Se、Cd、Pb共9种重金属含量及空间分布特征.分别采用地累积指数法及Hakanson潜在生态危害指数法,对农田土壤重金属污染程度及生态风险进行评价;同时利用多元统计分析方法,揭示了研究区农田土壤重金属各元素之间的相关性及污染来源.结果表明,研究区农田土壤各重金属含量偏低,呈轻度污染;但在靠近居住区、高速公路、铁路或小型畜牧厂(已关停)的部分点位中Zn或Cr存在明显富集,污染等级为中度或严重;各元素的生态危害指数大小依次为E_R(As)>E_R(Cu)>E_R(Pb)>E_R(Zn)>E_R(Ni)>E_R(Cr)>E_R(V),生态危害程度均为轻微;多元统计分析结果显示,灌溉水对As和Pb的影响较显著,农作物对As的影响较显著;Cr和Ni来源相似,主要受成土母质的影响;Pb、Zn、Cu等3种元素来源相似,主要来自于附近公路交通所排放的污染物;V和As的来源主要与历史工业污染的积累相关.

The concentrations and spatial distribution of V,Cr,Ni,Cu,Zn,As,Se,Cd and Pb in topsoils(0—20 cm)of the main agricultural production base in Xiqing District,Tianjin City.The heavy metals pollution and ecological risk were respectively evaluated with the Geo-accumulation Index and Potential Ecological Risk Index methods.The correlations among these heavy metals and the potential sources of the metals were studied with multivariate statistical analysis.The results showed that the heavy metals contents in the study area were relatively low,indicating the soil was slightly polluted.But Zn or Cr was significantly enriched and strongly/extremely polluted at some sites close to residential areas,highways,railways,or small livestock plants(closed).Potential ecological risk assessment indicated slight risk of soil pollution by heavy metals,and the risk by pollutant species was in the order:E_R(As)>E_R(Cu)>E_R(Pb)>E_R(Zn)>E_R(Ni)>E_R(Cr)>E_R(V).Multivariate statistical analysis revealed that effects of irrigation water on As and Pb were significant,and effects of crops only on As were significant.The sources of Cr and Ni were similar and could be attributed to soil parent material.The sources of Pb,Zn and Cu were similar and came mainly from the emissions of nearby road traffic.The sources of V,As were similar and mainly related to the accumulation of historical pollutions from industrial.