上海市崇明岛公路两侧土壤重金属污染研究

HEAVY METAL POLLUTION OF SOILS ALONGSIDE ROADS OF CHONGMING ISLAND OF SHANGHAI CITY

采集了上海市崇明岛陈海、北沿公路两侧土壤和灰尘样品270余个,测定了样品的Pb、Cd、Cu、Zn和Cr重金属含量。结果表明,陈海和北沿公路两侧土壤重金属Pb、Cd、Cu、Zn和Cr的平均含量达到27.7、0.279、25.8、91.8和77.6 mg/kg,土壤Cd污染较严重。采集的路面灰尘样品Pb、Cd、Cu、Zn和Cr的平均含量达到51.2、0.49、48.9、209和97.0 mg/kg,超过土壤背景值2～4倍,是土壤重金属的主要二次污染源。公路防护林体系较差的北沿公路路侧土壤纵向剖面(垂直于公路走向)重金属含量随距路肩距离增加呈指数下降,土壤重金属重污染区在距路肩15 m范围内。防护林体系较完善的陈海公路距路肩15 m范围内土壤重金属污染较小,土壤承金属重污染区出现在距路肩20～50 m范围内。

To assess heavy metai contamination induced by traffic at the vicinity of roads,a study of heavy metal levels in the soils and road dusts was carried out alongside two roads of different traffic intensity. 273 roadside soil and road dust samples were collected along the Chenhai road and Beiyan road of Chongming Island and the concentrations of heavy metals （Pb,Cd,Cu,Zn and Cr） were measured by atomic absorption spectrophotometry. The results showed that the average value of total soil Pb,Cd,Cu,Zn and Cr concentrations were 27. 7,0. 279,25.8,91.8 and 77. 6 mg/kg,respectively. Roadside soils were seriously polluted by Cd. The average value of total dust Pb,Cd,Cu,Zn and Cr concentrations were 51.2,0.49,48.9,209 and 97.0 mg/kg,respectively. Heavy metal concentrations of road dust were 2-4 times higher than the background values of Shanghai soils. It is indicated that road dust was a potential source of heavy metal contamination in the roadside environment. And protection forest of the roads played an important role in heavy metal distribution in the cross section. All measured heavy metal concentrations in roadside soils of Beiyan road,which had sparse protection forest, decreased exponentially with the increase of distance from the road; the maximum heavy metal value appeared within the distance of 15 m from Beiyan road. However, heavy metal concentrations of roadside soils within the distance of 15 m from Chenhai road, which had dense protection forest, were rather low in the cross section. Heavy polluted roadside soils alongside Chenhal road appeared in the distance between 20 m and 50 m from the road.