城市交通对道路周边土壤重金属污染影响的研究

Study on heavy metal pollutions in roadside soil

为研究城市公路交通对路边土壤重金属污染的影响,以北京市西三环主要立交桥路段为研究样区,采用火焰原子吸收光谱法,对土壤中重金属Ni,Cr,Pb,Cu,Zn,Cd的含量进行了测定,并采用改进的BCR连续提取法,对土壤样品中各种重金属的存在形态进行了分析。研究表明:除Cu外,道路周边土壤中其他重金属含量总体上均明显高于同一地区远离交通干道的清洁区土壤;其中Ni,Cr,Pb,Zn,Cd最高分别较清洁区高1.17倍、1.59倍、2.20倍、1.77倍和1.96倍。从各种重金属的形态分布特点看,Cd主要以酸可提取态和氧化物结合态存在;Pb主要以有机物与硫化物结合态存在;Cu,Cr,Zn,Ni主要以残渣态存在。

To study the distribution of the heavy metals in roadside soil polluted by vehicle exhaust, the soil samples are collected at the XISANHUAN highway in Beijing. Flame atomic absorption spectrophotometer was used to analyze the contents of heavy metals in the soils, and the improved BCR sequential extraction method was used to analyze the heavy metals form. The results show that the soils along highways are polluted obviously by Ni, Cr, Pb, Zn and Cd which are respectively 1.17 times, 1.59 times, 2.20 times, 1.77 times and 1.96 times as much as those in clean control zone soils. But Cu shows the different resuit, almost not influenced by vehicle exhaust. From the characteristic of heavy metals forms, Cd exists mainly in the acid extractable form and oxide combining form, Pb exits mainly in the organic and sulfide combining form, and Cu, Cr, Zn, Ni exists mainly in the residue form.