山东省广饶县土壤重金属来源、分布及生态风险

选取山东省广饶县作为研究区,采集300个表层土壤样品（0~20 cm）,测定As、Cd、Co、Cr、Cu、Hg、Mn、Ni、Pb和Zn等10种重金属含量;运用多元统计和地统计分析方法揭示广饶县土壤重金属元素的来源与空间分布特征,最后利用H?kanson潜在生态风险指数法评价重金属的潜在生态风险。结果表明：① 研究区土壤中Co和Pb的平均值低于山东省背景值,其他8种元素的平均值均超过山东省背景值;特别是Cd和Hg的平均含量分别达到山东省背景值的1.86倍和2.50倍,说明在土壤中存在明显的富集。② As、Co、Cr、Cu、Mn、Ni和Zn为自然源,受成土母质控制;Hg为人为源,主要来源于煤炭燃烧和工业排放;Cd和Pb受自然和人为因素共同控制。③ 成土母质控制着As、Cd、 Co、Cr、Cu、Mn、Ni、Pb和Zn的基本分布格局,不同土地利用类型的土壤Hg含量差别较明显,其高值区集中在城镇建设用地。④ 总体上,研究区为中等生态风险的偏高水平,其中Cd和Hg分别为中等和较高生态风险,其余8种元素处于低生态风险。

Sources,distribution and ecological risk of soil heavy metals in Guangrao county,Shandong province

A total of 300 samples in topsoils (0-20 cm) of Guangrao county, Shandong province were collected, and each sample was analyzed for As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, and Zn. The sources and spatial distribution of heavy metals were examined using multivariate analysis and geostatistics, and the ecological risk of heavy metals in soils was evaluated using H?kanson's method. The average contents of Co and Pb were lower than the background values of Shandong, and the average concentrations of the other heavy metals were higher than the background values of the province. In particular, the mean contents of Cd and Hg were 1.86 and 2.50 times their respective background values, indicating that there were obvious accumulations of Cd and Hg in surface soils. As, Co, Cr, Cu, Mn, Ni, and Zn mainly came from natural sources, and were controlled by parent materials. Hg originated from coal combustion and industrial emissions, and was greatly controlled by human activities. Cd and Pb were affected by both natural and human factors. Agricultural practices, especially the application of chemical fertilizers, contributed to the increased Cd contents, while the vehicles emissions were the main human inputs to the Pb contents. The spatial distributions of As, Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn were controlled by parent materials with the higher contents in the soils from lacustrine deposit and the Yellow River alluvium; there were significant differences among various land use types, and higher contents were observed around the urban area. Totally, the study area suffered the moderate ecological risk with the high value area corresponding to the urban area; the intense human activities have led to high ecological risk in the urban area. The level of ecological risk was the lowest in the northeast part, the high ecological risk was concentrated in the urban area and the surrounding area, and the other regions had middle ecological risk. Hg was at the considerable ecological risk level, and Cd was at the moderate ecological risk level, while other heavy metal elements were at the low ecological risk level.