新疆库尔勒市地表灰尘重金属污染及潜在生态风险

Pollution and potential ecological risk of heavy metals in surface dust in Korla,Xinjiang

从库尔勒市采集54个地表灰尘样品,测定其中Hg、Cd、As、Pb、Cr与Cu共6种重金属元素含量,采用内梅罗综合污染指数(NPI)、潜在生态风险指数(HRI)和生态风险预警指数(IER),评价了地表灰尘重金属污染及潜在生态风险。结果表明,库尔勒市地表灰尘中Hg、Cd、Pb、Cr和Cu等元素含量平均值分别为新疆土壤背景值的3.71、1.87、1.96、1.14和1.29倍。其中,Hg呈现重度污染,Cd、Pb、Cr、Cu呈现轻度污染,As呈现轻微污染,NPI平均值呈现重度污染。潜在生态风险评价结果表明,地表灰尘中Hg呈现较强生态风险,Cd呈现中等生态风险,As、Pb、Cr和Cu呈现轻微生态风险,HRI平均值为232.23,呈现中等生态风险。根据生态风险预警分级标准,地表灰尘中Hg污染处于轻警态势,Cd、Pb、Cu和Cr污染处于预警态势,As污染处于无警态势,IER平均值为4.91,处于中警态势。从空间分布格局来看,地表灰尘重金属污染及生态风险高值区分布于研究区北部。总体上,库尔勒市地表灰尘重金属污染风险相对较低。

A total of 54 surface dust samples were collected from Korla.The contents of six heavy metals(Hg,Cd,As,Pb,Cr and Cu)in those samples were determined.The pollution levels and potential ecological risk of heavy metals in surface dust were evaluated using Nemerow pollution index(NPI),ecological risk index(HRI),and ecological risk warning index(IER).Results showed that the average contents of Hg,Cd,Pb,Cr and Cu in the surface dust in Korla exceeded the corresponding background values of Xinjiang soils by 3.71,1.87,1.96,1.14 and1.29 times,respectively.Among them,the surface dusts were highly polluted by Hg,lowly polluted by Cd,Pb,Cr,Cu,and slightly polluted by As.The average NPI value fell into the high pollution level.Results of ecological risk assessment indicate that Hg in surface dust fell into high ecological risk level,while Cd fell into moderate ecological risk level,and As,Pb,Cr,and Cu fell into low ecological risk level.The average value of HRI was 232.23,being at the moderate risk level.According to the classification of ecological risk warning degree,Hg in surface dust fell into low ecological warning status,while Cd,Pb,Cu,and Cr fell into early ecological warning status,As fell into no ecological warning status.The average value of IER was 4.91,being at a moderate ecological warning status.Spatial distribution of heavy metals showed that areas with high pollution and ecological risk levels were mainly distributed in the northern part in the study area.Overall,the pollution risk of heavy metals in surface dust in Korla was relatively low.