公路交通对土壤重金属污染的研究

Heavy metal pollution along the highway area with the method of geo-accumulation index

目的评价公路交通引起的土壤中重金属污染。方法选择320国道马龙路段进行耕作土采样，用原子吸收光谱法和分光光度法分析土壤中重金属Cu、Cd、Pb、Zn、Cr、As、Ni含量，采用清洁对照区土壤剖面重金属含量作为参比值，应用地积累指数法对重金属污染叠加进行评价。结果研究区土壤中Cu、CA、Pb、Zn、Cr、As、Ni的含量显著高于对照区（P〈0．01）。Cd为中等污染～强污染，Pb为中等污染，Cr和Cu为轻污染～中等污染。污染晕带沿公路延伸方向展开，自公路起向其两侧强度运渐减弱，扩散范围约为150m。土壤对重金属元素的吸收及污染程度；Cd〉Pb〉Cr〉Cu〉As〉Zn〉Ni。结论公路旁土壤重金属污染以Cd、Pb和Cr为主，污染叠加重金属来源主要为机动车燃料、轮胎、机械中所含微量重金属成分。

Objective To assess the pollution of the heavy metals in the soil along the highway area caused by traffic. Methods The smaples of the farming soil were collected along the section of the highway No. 320 in Malong city . Heavy metals such as Cu, Cd, Pb, Zn, Cr , As and Ni were determined by atomic absorption spectrophotometry and spectrphotomter ,samples from a control section were also collected, the method of geo-accumulation index was used for detection. Results The content of Cu,Cd,Pb,Zn,Cr As and Ni in the soil of the observed area were obviously higher than those in the control section （P〈0.01）. The pollution was ranked as medium to high level for Cd, medium for Pb, and light to medium for Cr and Cu. The pollution spread to an extent of around 150 m,and the concentration decreased gradually. The soil pollution of the heavy metals was in the following order, Cd〉Pb〉Cr〉Cu〉As〉Zn〉Ni. Conclusion Cd,Pb and Cr were the major heavy metals polluting the soil along the highway and the source of pollution was the heavy metals from the exhaust fume, tires and mechanical parts of the automobiles.