天津市郊区土壤重金属的污染评价与来源解析

Pollution evaluation and source apportionment of heavy metals in soils from Tianjin suburbs, China

为了研究城市郊区土壤重金属的污染水平与来源,选取天津市郊区——西青区和滨海新区为研究区域,采集了农田、水塘/河边附近土地、道路绿化带、居民区和工厂附近土地等约2000 km^2范围内三类用地类型(农业用地、居住用地和工业用地)的286个土壤样品,调查了Cr、Ni、Cu、Zn、As、Pb和Cd 7种重金属的含量水平;通过多种污染和风险评估方法探讨土壤重金属的污染和风险水平;并通过多元统计分析方法进行重金属的来源解析。结果表明:该区域土壤中Cr、Ni、Cu、Zn、As、Pb和Cd的含量分别为71.47±20.49、32.15±19.66、27.77±12.77、99.78±53.20、17.59±8.69、30.27±9.72 mg·kg^(-1)和0.19±0.17 mg·kg^(-1);天津郊区土壤整体处于中度污染和低风险水平,以Cd和As为主要的污染物质;Cr和Ni主要为自然源,Cu、Zn、Pb和Cd来自自然源和人为源,As则主要为人为源。具有人为输入的土壤Cd和As占研究区土壤的半数以上,因此需要对当地土壤中的Cd和As进行重点监控。

To research the contamination level and sources of heavy metals in soil in suburban areas of Tianjin City, a total of 286 soil samples were collected from three land types(agricultural land, residential land, and industrial land)of soil over an area of 2000 km2, such as farmland, ponds, rivers, green belts, residential land, and manufacturing land. The contents of Cr, Ni, Cu, Zn, As, Pb, and Cd were determined. In addition, the contamination and risk level of heavy metals were discussed using several contamination evaluation and risk assessment methods. Moreover, the source apportionment of heavy metals was carried out by multivariate statistical analysis. The contents of sev-en heavy metals in these soil samples were 71.47±20.49, 32.15±19.66, 27.77±12.77, 99.78±53.20, 17.59±8.69, 30.27±9.72 mg·kg^-1 and 0.19±0.17 mg·kg^-1 for Cr, Ni, Cu, Zn, As, Pb and Cd, respectively. The results of the contamination level and ecological risk assessment showed that the soils in the suburbs of Tianjin were generally at moderate pollution and low ecological risk levels, with Cd and As as the main contaminants. The results of the multivariate statistical analysis revealed that Cr and Ni mainly originated from lithogenic sources, the origins of Cu, Zn, Pb, and Cd were a combination of lithogenic sources and anthropogenic sources, and As mainly originated from anthropogenic sources. Our results indicate that the soils with anthropogenic inputs of Cd and As accounted for more than half of the soil samples in the study area;therefore, it is necessary to focus on the monitoring of Cd and As in the local soil.