基于不同通车时间的路旁土壤重金属健康风险:以连霍高速郑州—商丘段为例

Health Assessment of Heavy Metals in Roadside Soils at Different Operation Time:A Case Study of Zhengzhou-Shangqiu Section Along the Lianyungang-Horgas Highway

以连霍高速郑商段不同通车时间的湾刘断面(通车11 a)和小王庄断面(通车4 a)为研究对象,按距离公路0、5、15、25、35、50、100、200、300和1 500 m采集土壤表层样品,用原子吸收分光光度法测定土壤重金属(Cd、Cu、Pb、Zn、Ni和Cr)含量,采用美国环境保护署(US EPA)推荐的健康风险模型对其开展健康风险评价.结果表明,公路通车运营时间越长,土壤重金属含量和健康风险越严重;随着离开公路路基距离的增加,土壤重金属含量和健康风险呈偏态分布或3阶多项式分布,峰值多出现在距路基15～50 m之间;土壤重金属的HQ和HI均远远小于1,不存在非致癌健康风险;各样点CRCr和TCR均略超过US EPA推荐的土壤治理标准(1×10-6),但低于一些专家提出的宽松标准(10-6～10-4),存在致癌风险的可能性,CRCr对TCR贡献率高达97.83%,Cr是最主要的致癌风险因子.

Two sample transects of Wanliu and Xiaowangzhuang on the Zhengzhou-Shangqiu section along the Lianyungang-Horgas highway were chosen to investigate the health risks of heavy metals（Cd,Cu,Pb,Zn,Ni and Cr） in roadside soils.Wanliu transect was opened in 1994,and Xiaowangzhuang in 2001.Mixed topsoil samples（0-15 cm） were collected at 0,5,15,25,35,50,100,200,300 and 1 500 m from the highway.Concentrations of soil heavy metals were measured with the method of AAS.Based on the health risk models recommended by US EPA,noncarcinogen and carcinogen health risks of soil heavy metals were evaluated.The results showed that the heavy metal concentrations and the health risks increased with the increase in operation time,indicating that the operation time might play a decisive role in heavy metal accumulations in roadside soil.Both the heavy metal concentrations and their health risks showed skewed distribution or cubic polynomial distribution with the distance from the highway roadbed.The highest concentration and the highest health risk occurred between 15-50 m from the highway roadbed.HQ and HI at bothsampling sites were lower than 1,which meant that there was no non-carcinogen risk.CRCrand TCR at both sample sites were beyond the standard suggested by US EPA,which meant there was possibly carcinogenic risk,but lower than the lenient standard raised by some other experts（10-6-10-4）.The contribution rate of CRCrto TCR reached 97.83%,and Cr was the major carcinogen risk factor.