连霍高速不同运营路段路旁土壤重金属分布及潜在生态风险

在连霍高速公路运营时间不同的湾刘和小王庄断面,按照距离公路的远近不同布设采样点,对路旁土壤重金属（Cd、Cu、Pb、Zn、Ni、Cr）的空间分布特征及土壤重金属潜在生态风险展开研究。结果表明：运营时间较长的湾刘断面（处于中等生态风险状态）路旁土壤重金属含量高于小王庄断面（总体处于轻微生态风险状态）。随着距公路路基距离的增加,多数重金属含量及潜在生态风险呈不规则偏态分布。湾刘断面的RI峰值出现在距路基50～100m之间,小王庄断面出现在距路基35 m处。土壤Cd是最主要的风险因子,对RI的贡献率平均为61.39%。土壤污染物潜在生态风险评价应根据所研究污染物种类和数量对H kanson潜在生态风险指数分级标准进行适当调整。

Spatial Distribution and Potential Ecological Risk Assessment of Heavy Metals in Roadside Soils along the Lianyungang-Horgas Highway

On Lianyungang-Horgas highway,two typical sampling transects along the Zhengzhou-Shangqiu section,Wanliu transect operated in 1994 and Xiaowangzhuang transect operated in 2001,were chosen to investigate the distribution and potential ecological risks of heavy metals(Cd,Cu,Pb,Zn,Ni,and Cr) in roadside soils.Soil samples were collected at different distances from the highway.The contents and spatial distribution of heavy metals in the soils were analyzed.The ecological risks of soil heavy metals were evaluated based on potential ecological risk index(RI) put fowward by H kanson.The results show that heavy metal concentrations and potential ecological risks on Wanliu transect(at moderate ecological risk level) were higher than those on Xiaowangzhuang transect(at slight ecological risk level) because of longer operated time.Most of the heavy metal concentrations and potential ecological risks present a skew distribution with the distance from highway roadbed.The highest risk indexes for different metals on Wanliu transect are observed at 50～100 m from highway roadbed,while those on Xiaowangzhuang transect at 35 m from the roadbed.The total risk index was mainly contributed by cadmium with the averagely proportion of 61.39%(ECd/RI).Therefore cadmium is the main factor influencing potential ecological risks.Potential ecological risk index is a rigorous method,because it includes not only concentrations of heavy metals,but also ecological effects and toxicological characters.To apply the method of RI in estimating the potential ecological risk of pollutants,the RI standards for different levels of potential ecological risk should be modified according to the pollutant amounts studied and their toxic-response factors.