天津市不同土地利用方式下土壤重金属污染特征及评价

目的]查明天津市土壤重金属污染的现状及污染源,为防治土壤重金属污染提供理论依据。方法]选择天津市工业用地、一般农田、水源地、养殖场及蔬菜基地土壤为研究对象,共采集146个样品。通过分析不同土地利用方式下的土壤重金属含量,采用单因子污染指数法和内梅罗综合污染指数法评价重金属污染程度,并对重金属的来源进行解析。结果]天津市土壤整体污染水平相对较轻,但土壤中均存在不同程度的重金属积累。Pb,Ag和Cd重金属污染面积较大,超标率分别为84.25%,76.71%和68.49%。不同土地利用类型影响到重金属的积累程度和积累类型。在研究区的5种土地利用方式中,蔬菜基地土壤中总重金属的累积程度最高,主要重金属包括Cd,Hg,As,Cr,Cu,Ni,V,Mn,Co和Ag等。工业用地土壤中的Zn污染显著高于其他土地利用方式,而农田土壤和畜禽养殖场土壤中的Pb污染较显著。结论]天津市土壤污染水平相对较轻。但从土地利用方式来看,工业用地、农田和畜禽养殖场土壤Pb及Zn等污染较重,在土地利用和管理中应该予以关注。

Pollution Characteristics and Assessment of Heavy Metal in Different Land-use Types in Tianjin City

Objective] The heavy metal pollution status and pollution sources in soil of Tianjin City was studied in order to provide a theoretical basis for preventing soil heavy metal pollution.Methods] A total of 146 samples were collected from the industrial areas, farmland, water sources, livestock farm and vegetable bases in Tianjin City. The pollution characteristics of heavy metals, mainly refering to the heavy metal content in soils of different land-use types, was evaluated by single factor pollution index and Nemero comprehensive pollution index method, and the sources of heavy metals were also discussed.Results] The results showed that different heavy metals were all found accumulated in soils, but the overall pollution level in Tianjin City was lower. The over standard rates of Pb, Ag and Cd were 84.25%, 76.71% and 68.49%, respectively. And land-use types affected the accumulation degree and categories of heavy metals. The vegetable base had the highest accumulations of total heavy metal among 5 land-use types, mainly including Cd, Hg, As, Cr, Cu, Ni, V, Mn, Co and Ag. The industrial area had the highest Zn concentration, while the Pb concentration was higher in the farmland, and livestock and poultry farmland.Conclusion] In an overall, the level of soil pollution in Tianjin City is relatively low. However, in terms of land-use types, the pollution levels of Pb and Zn in the industrial areas, farmland and livestock farms were higher, wherein it should be paid more attention to in the process of land use and management.