成乐高速两侧农田土壤重金属污染及潜在生态危害评价

Assessment of Heavy Metal Pollution and the Potential Ecological Hazard of Farmland Soils alongside Chengle Highway

【目的】为评价成乐高速公路两侧农田土壤重金属污染程度及其潜在生态危害。【方法】采用原子吸收分光光度法,对成乐高速公路两侧农田土壤中的Pb、Cd、Cu、Zn和Cr含量进行测定,采用单项污染指数法、内梅罗综合污染指数法、潜在生态危害指数法对成乐高速公路两侧农田土壤重金属污染及潜在生态危害进行评价。【结果】Cd的含量超过风险筛选值,Cr的含量明显低于风险值,Zn的含量临近风险值。彭山段农田土壤的Cd、Pb和Cr含量较高,夹江段农田土壤的Cu含量较高,东坡段农田土壤的Zn含量最高。5种重金属的含量随着距离的增加总体上呈下降趋势。5种重金属的单项污染指数顺序为Cd>Zn>Pb>Cu>Cr,5种重金属的综合污染指数为0.96,4个测试路段的综合污染指数的大小顺序为彭山段>东坡段>青神段>夹江段。5种重金属的潜在生态危害依次为Cd>Pb>Cu>Zn>Cr,潜在生态危害综合指数RI=42.17。【结论】Cd和Zn为成乐高速公路两侧农田土壤重金属污染的主要元素,Pb、Cu和Cr处于清洁状态,不同路段的不同重金属含量存在一定差异。成乐高速公路两侧农田土壤重金属污染与农田距离路基的垂直距离具有明显的负相关关系。成乐高速公路两侧农田土壤重金属污染处于警戒状态,临近轻度污染,具有轻微的生态危害风险,Cd污染的潜在生态危害相对较大,值得高度关注。

【Objective】This study aimed to evaluate the pollution of heavy metals and the potential ecological hazard in roadside farmland soils along Chengle highway.【Method】The contents of Pb,Cd,Cu,Zn and Cr in roadside farmland soils along Chengle highway were determined by using atomic absorption spectrophotometer.The pollution of heavy metals in soil and the potential ecological hazard were as-sessed by using single pollution index,comprehensive pollution index and Hakanson index.【Result】The average content concentration rates of Cd prove to be higher than the risk control standard of GB15618-2018,while the average content concentration rates of Cr prove to be lower than the risk control standard,and the average content concentration rates of Zn are near the risk control standard.The content of Cd,Pb and Cr in soils of Pengshan section is more than those of the other sections;the content of Cu in soils of Jiajiang section is higher than that of the other sections;the content of Zn in soils of Dongpo section is the highest.With the distance increased,the contents of the five heavy metals in soils decreased.The single pollution index of five heavy metals is in the following order:Cd>Zn>Pb>Cu>Cr;the comprehensive pollution index is 0.96,and the comprehensive pollution index of four sections is in the following order:Pengshan section>Dongpo section>Qingshen section>Jiajiang section.The potential ecological hazard of five heavy metals is in the following order:Cd>Pb>Cu>Zn>Cr,and the potential ecological hazard index(RI)is 42.17.【Conclusion】The results indicated that Cd and Zn are main contaminators in roadside farmland soils along Chengle highway,while Pb,Cu and Cr were almost clean.The contents of five heavy metals in different sections are different.There was a negative correlation between heavy metal pollution and vertical distance from Chengle highway.The heavy metal pollution in roadside farmland soils along Chengle highway is warning and near slight pollution,and the potential ecological hazard is slight.But Cd pollution is of more ecological risk and deserves huge attention.