铁路交通对铁路旁土壤重金属污染的影响——以陇海铁路郑州—圃田段为例

以陇海铁路郑州-圃田段为例,在野外调查、采样和实验室分析的基础上,探讨了铁路交通对周围土壤N i、Pb、Cr、Zn、Cu和Cd六种重金属含量与分布的影响。结果表明,铁路南侧农田土壤六种重金属元素都出现不同程度的富集,最大含量均分布在距铁路路基30m的范围内,随着距离的增加,各重金属元素含量表现出不同的下降趋势。土壤各重金属污染程度的次序为:Zn>Pb>Cd>Cu>Cr>N i。土壤Pb和Zn污染最为严重,近路基处为重度污染,随着距路基距离的增加,由中度污染逐渐变为轻度污染。土壤N i和Cr虽不构成污染,但仍具有明显的铁路影响特征。在距路基10 m范围内为土壤重金属重度污染带,10~100 m范围内为中度污染带,100~500 m范围内为轻度污染带。

Influence of Railway Traffic on Heavy Metal Contamination in Railroad- Soils:a Case Study on the Zhengzhou- Putian Section of the Long-Hai Railway

The concentration of heavy metals(Ni,Pb,Cr,Zn,Cu and Cd) in the soils on the southern side of Zhengzhou-Putian section of the Long-Hai Railway was analyzed.The sampling sites were distributed at different distances from the railway.Soils were sampled to an average depth of 15cm.Cu,Zn,Cr and Ni were determined by atomic absorption spectrophotometry(AAS) method,and Pb and Cd by GF-AAS method.The results show that highest contents of all the six metals distributed within 30 m from the railway.With the increase of distance from the railway,the concentration of the six heavy metals decreased in different tendency.In particular,the different kinds of kurtosis of the heavy metal contents were locate within 100 m from the roadbed of the railway.The order of the pollution extents of the soils was Zn>Pb>Cd>Cu>Cr>Ni according to the single factor pollution index(Pi) of these heavy metals.At the same time,it was found that the biggest accumulation of Zn and Pb was in the soil near the railway roadbed.Then with the increase of the distance from the railway roadbed,Zn and Pb in the soils decrease obviously.Nevertheless,the pollution extents of these two elements are rather apparent at a distance beyond 500 m from the roadbed.The accumulation of Ni and Cr in the soil did not reach pollution levels,but the influence of the railway on the accumulation of soil Ni and Cr was obvious compared with the control site.The integral pollution index(IPI) ranges from 1.42 to 3.98,and the highest IPI appears at the roadbed.In terms of the distances from the railway,the pollution extents of the soil in the study area could be divided into three pollution belts.The soil within 10 m from the railway belongs to severe heavy metal contamination,from 10 to 100 m to moderate contamination,and from 100 to 500 m to mild contamination.