不同土地利用方式下北京城区土壤的重金属累积特征

Accumulation of heavy metals in urban soils under different land uses in Beijing

对不同土地利用方式下城市土壤的采样调查表明,北京市城市土壤Cd、Cu、Pb和Zn含量显著高于其相应的土壤背景值,As、Ni与背景值无显著差异.在工业、住宅、商贸、交通边缘带(道路)、公园、城市广场和校园7种土地利用方式下,工业区土壤Cd、Cu、Ni、Pb和Zn含量均居首位,且Cu、Pb和Zn含量达到污染等级;公园土壤的As水平最高,但仍处于清洁水平.As、Cd、Cu、Ni、Pb和Zn综合累积程度由高到低的顺序为工业区>公园>商贸区≈校园>住宅区≈城市广场>交通边缘带.工业区土壤总体表现为重金属轻度污染;公园、商贸区、校园和住宅区土壤重金属处于尚清洁水平;城市广场和交通边缘带土壤重金属处于清洁水平.不同土地利用方式对城市土壤的重金属含量有一定影响.

Soil samples in industrial areas,residential areas,commercial areas,traffic greenbelts,parks,squares and campuses of Beijing were collected to assess the accumulation of heavy metals. The concentration ranges of heavy metals in urban soils were As： 2. 98 ～ 28. 0; Cd： 0. 115 ～ 0. 649; Cu： 13. 7 ～ 741; Ni： 15. 4 ～ 214; Pb： 15. 0 ～ 429,and Zn 34. 8 ～ 891 mg·kg^-1. There were no significant differences in As and Ni concentrations between urban soils and the background in Beijing,while Cd,Cu,Pb,and Zn were higher than the background concentrations in Beijing. The level of heavy metals in soils was affected partly by the usage of soils. The soils in industrial areas had the highest concentrations of Cd,Cu,Ni,Pb,and Zn,and the pollution indexes of Cu,Pb,and Zn were higher than 1. Soil concentration of As is the highest in parks,while the pollution index of As was lower than 1. The survey revealed that soils in industrial areas were polluted lightly with the composite pollution indexes in the order of industrialized areas parks areas campus residential areas squares traffic greenbelts. The level of heavy metal accumulation in urban soil was relatively light compared with some other cities in China.