细河流域农田土壤重金属污染评价及来源解析

由于长期接纳沈阳市工业废水和生活污水,细河水质和周边土壤污染严重。2015年10月采集细河流域农田表层(0~20 cm)土壤样品134份,分析土壤中重金属Hg、As、Pb、Cd、Ni、Cr、Zn和Cu的含量分布特征并进行污染评价,首次采用正定矩阵因子分析法(PMF)对该地区8种重金属来源进行分析,为土壤重金属源解析方法学评价提供依据。结果表明:细河流域农田土壤中Hg、As、Pb、Cd、Ni、Cr、Zn、Cu含量范围分别为0.04~1.85、4.80~11.70、10.80~36.70、0.09~1.50、22.30~47.40、19.60~104.00、71.40~242.00、31.20~105.00 mg·kg~(-1),其中Hg、Cd、Zn、Cu、Ni和Cr含量均值是沈阳市土壤背景值的3.80、2.50、2.04、2.03、1.14倍和1.02倍,Cd、Cu和Hg的含量超过土壤环境质量标准(GB 15618—1995)样点比例分别为48%、9%、9%。单因子污染指数评价结果显示Hg和Cd污染最为严重,污染指数均值分别为4.52和2.96;内梅罗综合污染指数均值为4.13,说明研究区域总体为重度污染。PMF模型解析出重金属污染来源有:工业污染源贡献率36.5%,交通污染源和大气沉降综合污染源贡献率23.5%,农业污染源贡献率20.8%,自然成土母质源贡献率19.2%。

Evaluation and source apportionment of heavy metal pollution in Xihe watershed farmland soil

Long-term discharging of industrial and domestic waste water into Xihe, Shenyang, decreased the quality of water as well as the surrounding soil. In October 2015, 134 topsoil samples were collected from the Xihe watershed farmland soil. Distribution characteristics of heavy metals(Hg, As, Pb, Cd, Ni, Cr, Zn and Cu) in the topsoil of this area were analyzed and evaluated. The results indicate that the contents of Hg, As, Pb, Cd, Ni, Cr, Zn and Cu ranged from 0.04 to 1.85, 4.80 to 11.70, 10.80 to 36.70, 0.09 to 1.50, 22.30 to 47.40, 19.60 to 104.00, 71.40 to 242.00 and 31.20 to 105.00 mg·kg^-1, respectively; The mean contents of Hg, Cd, Zn, Cu, Ni and Cr in topsoil were higher than background values of Shenyang soil with 3.80, 2.50, 2.04, 2.03, 1.14 and 1.02 times, respectively, which suggested there were varying degrees of enrichment of heavy metals in study soils; Compared to the National Standard for Soil Environment Quality(GB 15618-1995), the exceeding rates of Cd, Cu and Hg were 48%, 9%, 9%. The mean values of single factor pollution indexes of Hg and Cd were 4.52 and 2.96, which were considered as the dominant elements causing heavy metal pollution in the soil. The average comprehensive pollution index of soil heavy metal was 4.13, suggesting severe pollution in this area. The sources of heavy metals was explored by Positive Matrix Factorization(PMF) model, which showed there were four pollution sources:industrial pollution(contribution rate 36.5%), traffic pollution and atmospheric precipitation comprehensive pollution(contribution rate 23.5%), agriculture pollution(contribution rate 20.8%), and soil parent material(contribution rate 19.2%).