宝鸡市金陵河下游土壤-沉积物重金属污染生态风险评价和来源解析

Ecological risk assessment and source analysis of soil-sediment heavy metals in the lower reaches of Jinling River in Baoji city

为研究宝鸡市金陵河下游土壤和沉积物重金属的来源,采集金陵河下游土壤42份及沉积物41份样品,使用高精度X射线荧光光谱检测仪测定8种重金属(Pb、Cd、As、Cr、Mn、Ni、Cu和Zn)含量。对土壤和沉积物重金属含量进行了对比分析,揭示了Pb、Cd、As、Cr、Mn、Ni、Cu、Zn的空间分布特征。采用单因子潜在生态风险指数、综合生态风险指数进行重金属元素生态风险评价,利用PMF模型识别重金属污染来源及其贡献率,并结合地统计方法识别各来源的污染区域。结果表明:土壤重金属含量均值大小顺序为:Mn>Zn>Cr>Pb>Cu>Ni>As>Cd,沉积物重金属的平均含量大小顺序为:Mn>Zn>Cr>Ni>Cu>Pb>As>Cd;金陵河下游土壤与沉积物重金属元素在空间上分布有明显的差异性,土壤重金属浓度高值区在蟠龙山村与翟家坡村附近,沉积物重金属浓度高值区在姚家寨和铁路周围;金陵河下游土壤与沉积物中Cd属于强风险水平,土壤平均综合生态风险为轻度风险,沉积物平均综合生态风险为中度风险;金陵河下游土壤重金属的主要来源是工业源(36.85%)、自然源(19.12%)、农业源(23.42%)和交通源(20.61%),沉积物重金属的主要来源是工业源(48.32%)、自然源(33.27%)和农业源(18.41%)。

To study the sources of heavy metals in soil and sediment in the lower reaches of the Jinling River in Baoji,42 soil and 41 sediment samples were collected,the contents of eight heavy metals(Pb,Cd,As,Cr,Mn,Ni,Cu and Zn)in soil and sediment were determined by high precision X-ray fluorescence spectrometer,the spatial distribution characteristics of Pb,Cd,As,Cr,Mn,Ni,Cu,and Zn were analyzed,ecological risk of heavy metals were assessed by using single factor potential ecological risk index and comprehensive ecological risk index,and the pollution sources and contribution rates of heavy metals were identified by using PMF model.The results revealed that the mean order of heavy metal contents in soils was:Mn>Zn>Cr>Pb>Cu>Ni>As>Cd,and the mean order of heavy metal contents in sediments was:Mn>Zn>Cr>Ni>Cu>Pb>As>Cd.There are significant spatial differences in the distribution of heavy metals in the soil and sediment in lower reaches of the Jinling River,the areas with higher concentration of soil heavy metals are near Panlongshan village and Zhaijiapo village,while the areas with higher concentration of sediment heavy metals are around Yaojiazhai and the railway.Cd in the soil and sediment in this region is at a strong risk level.The average comprehensive ecological risk of soil heavy metals is mild,while the average comprehensive ecological risk of sediment heavy metals is moderate.Source apportionment showed that the main sources of soil heavy metals in the region are industrial source(36.85%),natural source(19.12%),agricultural source(23.42%)and traffic source(20.61%),the main sources of heavy metals in sediments are industrial source(48.32%),natural source(33.27%)and agricultural source(18.41%).