南京市不同功能城区土壤中重金属Cu、Zn、Pb和Cd的污染特征

将南京城市建成区分为矿冶区、开发区、商业区、城市广场、风景区、老居民区等6大功能区,选择采集土壤样本56个,用原子吸收光谱仪选择分析了土壤中重金属元素的全量和活性形态含量.结果表明,南京城市土壤中Pb、Cu、Zn和Cd的总量分别为:117.1±103.7mg·kg^-1,39.86±39.9mg·kg^-1,273.3±131.6mg·kg^-1和1.13±0.7mg·kg^-1.矿冶区、老居民区、商业区、新开发区、城市广场和风景区的内梅罗重金属综合污染指数分别为:5.4、4.9、3.4、1.6、2.4和2.3.矿冶区以Pb、Cd的强度积累为特征,但活性形态的比重较小.而城市中心的居民区和商业区Zn的积累最显著,并且所测定的重金属的醋酸盐浸提态含量明显较高.除了风景区和城市市民广场外,城市中心区的重金属均表现出较明显的表聚性.城市活动区土壤Pb、Cd的强烈积累可能已经对人类健康构成了威胁.

Soil Pollution of Cu,Zn,Pb and Cd in Different City Zones of Nanjing

The Nanjing city was divided into six zones as smelter industry, inner commercial, inner residence, newly developed, urban greenland and preserved scenic. In each zone, soil samples were randomly collected by triple subsampling technique. Total 56 soil samples were digested by mixed solution of nitric, chloridic and sulphatic acids and by sequential extractants respectively according to the standard methods. The total and fractional heavy metals were determined by AAS. The mean total content of Pb, Cu, Zn and Cd of the soils from smelter industry, inner commercial, inner residence, newly developed, urban greenland and preserved scenic zone was 117.1±103.7mg·kg^-1 ,39.86±39.9mg·kg^-1,273.3±131.6mg·kg^-1 and 1.13±0.7mg·kg^-1 , with the overall pollution index being 5.4,4.9,3.4,1.6,2.4 and 2.3 respectively. The pollution in the smelter industrial zone was characterized by high concentration but low chemical mobility of Pb and Cd, while that in inner cities by high concentration of lead and zinc with quite larger acelatic acid extractable pool. Except for the soils from newly developed and preserved zones, the heavy metals were more or less superficial in respect to their depth distribution in the urban soils. The dramatic soil pollution of Pb and Cd in the urban area might cause any health risks for children, whose activities are believed to happen in a relative limited area. The future research on urban soil pollution should pursue the effect of soil pollution on human environment in the urban area.