有色金属矿业城市典型村镇土壤重金属污染评价及来源解析

为了解铜陵市村镇土壤重金属污染程度和潜在生态风险水平，在顺安镇、钟鸣镇和义安经济开发区大致均匀布设67个采样点位，采集表层土壤样（包括地表灰尘和河道沉积物），通过测试Cu、Zn、Pb、Cr、Cd、As和Ni等重金属含量及土壤pH值，剖析土壤重金属含量的空间分布特征，评估土壤重金属污染程度和潜在生态风险水平，并解析土壤重金属来源.结果表明，研究区土壤pH呈弱酸性，土壤重金属Cu、Zn、Pb、Cr、Cd、As和Ni含量均值分别为铜陵市土壤背景值的4.94、2.89、2.07、0.94、7.97、4.03和2.02倍，总体上呈现西高东低的变化特征.内梅罗污染指数表明，Cu、Cd、As和Pb属于重度污染，Zn和Ni分别属中度和轻度污染，Cr为无污染；不同用地类型内梅罗综合污染指数大小排序为：河道>城镇>工业用地>菜地>农业用地>山林>村庄，研究区总体属于重度污染水平.土壤重金属潜在生态风险系数大小排序为：Cd>As>Cu>Pb>Ni>Zn>Cr，其中Cd处于极高风险，Cu和As处于中等风险，其余各元素均处于低风险水平；不同用地类型潜在生态风险水平排序为：河道>城镇>工业用地>菜地>农业用地>村庄>山林，其中工业用地、菜地和城镇总体达很高风险水平，农业用地达高风险水平，村庄和山林属于中等风险.主成分分析表明，研究区Cu、Zn、Pb、Cd和As的主要来源是当地金属矿业污染；Cr主要来自地质背景和金属矿业污染；Ni主要来源为化石燃料燃烧.

Contamination Assessment and Source Apportionment of Soil Heavy Metals in Typical Villages and Towns in a Nonferrous Metal Mining City

To investigate the soil contamination degree and potential ecological risk level of heavy metals in villages and towns in Tongling City, we collected 67 surface soil samples (including surface dusts and river sediments) from the typical districts, namely Shun''an Town, Zhongming Town, and Yi''an Economic Development Zone, and measured the contents of heavy metals including Cu, Zn, Pb, Cr, Cd, As, and Ni. Then, spatial distribution characteristics of heavy metals were analyzed, and their contamination degree and potential ecological risk were assessed. Finally, source apportionment of soil heavy metals was conducted using factor analysis. The results showed that the soil pH was weakly acidic in the study area, and the average contents of Cu, Zn, Cr, Cd, As, and Ni were 4.94, 2.89, 2.07, 0.94, 7.97, 4.03, and 2.02 times their soil background values in Tongling City, respectively. In general, the contents of soil heavy metals in the western part were higher than those in the eastern part across the studied area. According to the Nemerow pollution index, Cu, Cd, As, and Pb reached pollution levels; Zn, and Ni approached moderate pollution levels; and Cr belonged to the no pollution degree category. The Nemerow comprehensive pollution index of different land types was arranged in the order of river bed>town district>industrial land>vegetable land>agricultural land>mountain forest>village. On the whole, the contamination degree of soil heavy metals in the study area reached severe pollution levels. The order of potential ecological risk coefficients of soil heavy metals was Cd>As>Cu>Pb>Ni>Zn>Cr, in which Cd belonged to the extremely high risk level, Cu and As belonged to the medium risk level, and the others were all low risk levels. The potential ecological risk levels corresponding to different land types were as follows:river bed>town distribution>industrial land>vegetable land>agricultural land>village>mountain forest. The industrial land, vegetable land, and town district generally reached a very high risk level, and the agricultural land reached a high risk, whereas both village and mountain forest land showed a medium risk. Principal component analysis showed that Cu, Zn, Pb, Cd, and As in the study area were derived from local metal mining pollution; Cr was from both the geological background and metal mining pollution; and Ni mainly came from fossil fuel combustion.