辽河铁岭段两岸河岸带土壤重金属分布及风险评价

Heavy Metal Pollution and Risk Assessment of Riparian Soils along Liao River in Tieling Region

通过测定辽河保护区铁岭段河岸带土壤重金属的全量和土壤的理化性质和各项指标,分析了其空间分布特征,运用潜在危害指数法对流域内土壤重金属进行评价.从空间分布上看,河岸带左岸重金属平均质量分数为:Cu 16.86mg/kg,Pb 22.10mg/kg,Zn 80.02mg/kg,Cd 0.41mg/kg;河岸带右岸重金属Cu17.53mg/kg,Pb 20.70mg/kg,Zn 87.23mg/kg,Cd 0.33mg/kg.左岸只有Cu低于背景值,右岸铜、铅质量分数低于背景值,而其他均高于背景值.与国家土壤环境质量标准中的一级标准相比,除镉外,均低于国家一级标准.从单项潜在生态风险评价来看,左右两岸河岸带土壤中重金属Cd处于强潜在生态风险,其他元素处于轻微的潜在风险.各个元素的单因子潜在生态风险指数从小到大依次为Cd<Pb<Cu<Zn.从综合潜在危害系数(RI)看,左右两岸属于轻微危害水平,说明辽河干流铁岭段生态环境处于较优水平.

Through the determination of total amount of soil heavy metal and physical and chemical properties and the indicators of soil in riparian zone of Tieling section of the Liao River,the spatial distribution characteristics are analyzed,and the heavy metals of riparian zone are evaluate by using the potential hazard index method.From the point of spatial distribution,the average mass fractions of heavy metals in the left bank of river are：Cu 16.86mg/kg,Pb 22.10mg/kg,Zn 80.02mg/kg,Cd0.41mg/kg,while the values in the right bank are Cu 17.53mg/kg,Pb 20.70mg/kg,Zn 87.23mg/kg,Cd 0.33mg/kg.In left bank,only the value of Cu is lower than the background values;in the right bank,the values of Cu and Pb are lower than the background values.Comparing with the primary standard of the national soil environmental quality standards,in addition to Cd,the average mass fractions of heavy metals are lower than the national level standards.From the point of individual potential ecological risk assessment,Cd in the riparian zone of both side of Liaohe River has strong potential ecological risk,and the other elements have minor potential risk.The order of potential ecological risk index of single factor in each element is Cd〈Pb〈Cu〈Zn.From the point of potential comprehensive pollution index,both sides of riparian zone have minor damage,and it indicates that the ecological environment in Tieling section of Liao River has a good level.