基于小流域尺度的矿区农田土壤重金属源解析

为定性定量分析浏阳七宝山矿区耕地土壤重金属污染来源及源贡献率，以农业小流域为研究尺度，基于GIS网格布点法共采集了60个0～20 cm耕层土壤样品，测定其Cd、As、Fe、Mn、Cu、Zn和Pb的含量及pH值，并综合运用地统计、多元统计和正定矩阵因子分析（PMF）模型等方法对小流域耕地土壤典型重金属污染元素进行定量源解析。结果显示：Cd、As、Cu、Zn和Pb的均值分别是湖南省土壤背景值的10.0、2.1、4.5、2.0倍和4.8倍，且超过农用地土壤污染风险筛选值（除As外）；多元统计分析将7种元素分成3大类，第一类为Fe和Mn，第二类为As和Pb，第三类为Cd、Cu和Zn;PMF模型解析出7种重金属均受到干湿沉降和历史上污水灌溉的影响，此外，Fe和Mn主要由成土母质控制，Cd、Cu和Zn主要源于矿冶活动（尤其是Cd）,As和Pb则主要来源于农药化肥和交通运输。研究表明，流域内耕地土壤重金属污染的主要来源是人类活动，包括工农业活动和交通运输。

Source analysis of heavy metal pollution in farmland soil in a mining area based on a small watershed scale

Scientific diagnosis and accurate identification of the sources of heavy metals pollution in soil is an important premise of soil environmental prevention and control. To analyze the source and contribution of heavy metals in the cultivated soil in the Qibaoshan mining area in Liuyang on a small agricultural watershed research scale, 60 soil samples of 0-20 cm cultivated layer were collected based on the GIS net layout sampling method, and Cd, As, Fe, Mn, Cu, Zn, and Pb content and the soil pH were determined. The methods of geostatistics, multivariate statistics, and PMF modeling were used to quantitatively analyze the source of typical heavy metals pollution in cultivated soil in the small watershed. The results showed that the mean values of Cd, As, Cu, Zn, and Pb were 10.0, 2.1, 4.5, 2.0 times, and 4.8 times of the background values of soil in Hunan Province, respectively, and exceeded the soil risk screening value for agricultural land (except As). Seven elements were divided into three categories using multivariate statistical analysis, the first category was Fe and Mn, the second As and Pb, and the third Cd, Cu, and Zn. The PMF model showed that all heavy metals were affected by dry and wet sedimentation and historieal sewage irrigation. In addition, Fe and Mn originated mainly from soil parent material sources, Cd, Cu and Zn from mining and smelting activities(especially Cd), and As and Pb pesticides, fertilizers, and transportation. The results showed that human activities, including industrial and agricultural activities and transportation, were the main sources of heavy metal pollution in cultivated soil in the watershed.