北京市区绿地土壤中铅等重金属累积及空间分异特征

SPATIAL DISTRIBUTION AND ACCUMULATION CHARACTERISTICS OF PLUMBUM AND OTHER HEAVY METALS IN GREENBELT SOIL IN BEIJING URBAN AREA

为考察北京市区绿地土壤重金属累积及其空间分异特征,在北京市区采集了151个绿地表层(0~20cm)土壤样品,并通过地统计分析方法研究了土壤样品中Pb等重金属元素累积及空间变异特征。结果表明:1)北京市区内绿地土壤重金属Pb、Cr、Zn、Cu的含量分别为26.9,0.33,49.64,76.85 mg/kg,存在累积现象,地积累指数分别为0.13、0.09、-0.22和-0.64,Cr和Cu地积累级别为2级,Zn和Pb地积累级别为1级。2)Pb和Zn的半变异函数最佳理论模型为高斯模型,Cr和Cu则分别为指数模型和球面模型。Pb在空间变异上为极弱的空间自相关,其余3种重金属则呈中等强度的空间自相关。3)Cu和Zn在中部和东北部含量较高,Pb中部地区含量较高,从中部向外围呈递减的趋势。Cr高值区分布比较零散,呈不规则斑块状分布。

In order to master the accumulation and spatial distribution of heavy metals in greenbelt soil in Beijing urban area,a total 151 samples were collected,and the accumulation and spatial distribution of the metals were analysed by geostatistical analysis method. The results showed that： 1） The average values of total Pb,Cr,Zn and Cu content were 26. 90,49. 64,76. 85,31. 44 mg/kg,respectively. The average value of soil heavy metals was higher than the soil background value of Beijing,which indicated accumulation of the heavy metals in urban greenbelt soil. Geo-accumulation index of Pb,Cr,Zn and Cu were 0. 13,0. 09,-0. 22 and-0. 64,accumulation levels of Cr and Cu were at level 2,while the levels of Pb and Zn were at level 1. 2） Gaussian was the best variation function model to predict Pb and Zn,while the best model for Cr and Cu were exponential model and spherical model. In space variation,Pb presented weak spatial autocorrelation,all other heavy metals presented a moderate spatial autocorrelation. 3） The average values of total Zn and Cu were higher in north east and central region. The value of Pb was higher in central region and gradually diminished from the central to the periphery,while distribution of high value of Cr was scattered and irregular plaque.