Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300170, China.
School of Environmental Science & Safety Engineering, Tianjin University of Technology, Tianjin 300384, China.
Int J Environ Res Public Health. 2022 Aug 14;19(16):10013. doi: 10.3390/ijerph191610013.
Heavy metal pollution in soil has received much attention in recent decades. Many studies have analyzed the interaction between specific soil quality and soil heavy metal pollution. However, there is little information about the pollution status, spatial distribution and pollution sources of heavy metals in the province of Tianjin. In this paper, the distribution characteristics and pollution sources of heavy metals in soil were studied by means of the surface soil of Tianjin, as the study area and object, conducted in combination with land use types, using multiple data analysis and multivariate statistics, while the pollution levels were evaluated by various indices. The results showed the mean contents of the seven heavy metals of the studied elements followed an increasing order of Cd (0.15 mg/kg) < As (11.9 mg/kg) < Cu (24.3 mg/kg) = Pb (24.3 mg/kg) < Ni (27.9 mg/kg) < Cr (70.7 mg/kg) < Zn (79.1 mg/kg). The median values of Cr and Ni were lower than the background values and did not exceed the screening values at the points, and the median values of Cu, Zn and Pb were close to the background values, while the median contents of As and Cd were higher than the background values. The highest accumulation of heavy metals was found in grassland, and the coefficient of variation of heavy metal contents were higher in garden land, industrial and mining storage land, residential land and transportation land, indicating that the soil heavy metal contents under these land use types were more significantly disturbed by human factors. The evaluation results of the ground accumulation index method showed that the soil in Tianjin was free of pollution, except for Cd, which was at the non-polluted to moderately polluted level. The Nemero integrated pollution index evaluation method and the pollution load index evaluation method together showed that the integrated pollution levels of heavy metals in Tianjin soils were both at no pollution level/safety level. Apart from Cd and As, which were not correlated, the other heavy metals were correlated with each other two by two. Cd, Pb and Zn were the main pollution contributors from traffic, industry and other anthropogenic factors, while Cr and Ni were the main pollution contributors from soil parent material, and Cu was the main pollution contributor from mining and metal smelting. In addition, As was presumed to be the main source of pollution contribution from agriculture and surface runoff.
近年来，土壤重金属污染受到了广泛关注。许多研究分析了特定土壤质量与土壤重金属污染之间的相互作用。然而，关于天津市土壤重金属的污染状况、空间分布和污染源的信息却很少。本研究以天津市表层土壤为研究区和对象，结合土地利用类型，采用多种数据分析和多元统计方法，研究了重金属在土壤中的分布特征和污染源，并采用多种指标对污染水平进行了评价。结果表明，所研究元素的七种重金属的平均含量顺序为 Cd（0.15mg/kg）<As（11.9mg/kg）<Cu（24.3mg/kg）=Pb（24.3mg/kg）<Ni（27.9mg/kg）<Cr（70.7mg/kg）<Zn（79.1mg/kg）。Cr 和 Ni 的中位数低于背景值，各点位未超过筛选值，Cu、Zn 和 Pb 的中位数接近背景值，而 As 和 Cd 的中位数高于背景值。重金属的最高积累量出现在草地中，园地、工矿仓储用地、居住用地和交通运输用地的重金属含量变异系数较高，表明这些土地利用类型下的土壤重金属含量受人为因素的干扰更为显著。基于地积累指数法的评价结果表明，天津市土壤无污染，除 Cd 处于无污染至中度污染水平外。基于 Nemero 综合污染指数评价法和污染负荷指数评价法的评价结果均表明，天津市土壤重金属的综合污染水平均处于无污染/安全水平。除 Cd 和 As 不相关外，其他重金属两两之间均相关。Cd、Pb 和 Zn 是交通、工业等人为因素的主要污染贡献因子，Cr 和 Ni 是土壤母质的主要污染贡献因子，Cu 是矿业和金属冶炼的主要污染贡献因子。此外，As 被认为是农业和地表径流的主要污染源。
