基于PMF模型的宝鸡铅锌尾矿库周边农田土壤重金属源解析

Sources apportionment of heavy metals in farmland soil around lead-zinc tailings reservoir based on PMF model

以宝鸡凤县某铅锌尾矿库及周边农田表层土壤为研究对象,测定样品中重金属Pb、Cd、Hg、Zn等的含量,采用单因子污染指数(P i)、内梅罗综合污染指数(P综)及Hakanson生态风险指数(RI)确定土壤污染状况的基础上,结合正定矩阵因子(PMF)受体模型,定量解析农田土壤重金属的来源。结果表明,农田土壤中Pb、Cd、Hg、Zn、Cu、As平均值含量分别是64.69mg·kg-1、0.23mg·kg-1、0.18mg·kg-1、104.42mg·kg-1、37.69mg·kg-1、14.33mg·kg-1,其均值含量分别是陕西省土壤元素背景值的5.73、2.56、2.00、1.84、1.76、1.28倍。内梅罗综合污染指数显示,农田土壤中度及重度污染样点比例分别为41.03%和38.46%。Hakanson生态风险指数分析表明,农田土壤中76.92%的样点属强及以上风险等级,Pb、Cd、Hg为其主要生态风险因子。正定矩阵因子受体模型解析结果显示,源1主要载荷As和Zn,对其贡献率分别为100%和63.3%,为农业、铅锌选矿和交通活动三因素混合源;源2对Ni、Cr、Cu的载荷率分别为100%、87.4%、69.5%,为自然源;源3主要对土壤造成Hg污染,其贡献率为66.1%,为化石燃烧释放源;源4为铅锌选矿和交通活动混合源,对Cd解释率为64.0%;源5对农田土壤Pb的载荷率为86.6%,为铅锌工业活动源。

The contents of heavy metals,including Pb,Cd,Hg and Zn etc.,were determined in the surface soil of a lead-zinc tailings reservoir and surrounding farmland in Baoji Fengxian County.Moreover,the single factor pollution index(P i),Nemero comprehensive pollution ind ex(P comprehensive)and Hakanson ecological risk index(RI)were used to determine the soil pollution status,and quantitative sources of heavy metals in farmland soil combined with the positive definite matrix factor(PMF)receptor model.The results showed that the average content of Pb,Cd,Hg,Zn,Cu and As in farmland soil were 64.69 mg·kg-1,0.23mg·kg-10.18mg·kg-1,104.42mg·kg-1,37.69mg·kg-1 and 14.33mg·kg-1,which were 5.73,2.56,2.00,1.84,1.76 and 1.28 times of the background values of soil elements in Shaanxi Province respectively.Furthermore,Nemero comprehensive pollution index showed that the proportion of moderate and high pollution samples in farmland soil were 41.03%and 38.46%,respectively.RI indicated that 76.92%of samples in farmland soil belonged to strong or above risk level,and Pb,Cd and Hg were the main ecological risk factors.In addition,the sources apportionment of heavy metals in the farmland soil based on PMF indicated that As and Zn pollution were mainly influenced by mixed sources 1(agriculture,lead-zinc metallurgy and transportation)and the contribution of source 1 for As and Zn were 100%and 63.3%,respectively.The source 2 was natural source and its contribution for Ni,Cr and Cu were 100%,87.4%and 69.5%,respectively.The source 3 mainly causes Hg pollution to the soil,and its contribution rate is 66.1%,which is the source of fossil combustion release.Source 4 is lead and zinc beneficiation and transportation active mixed source,the interpretation rate of Cd is 64.0%.The load rate of source 5 on farmland soil Pb is 86.6%,which is lead and zinc industry activity source.