内蒙古中东部地区草原土壤中重金属分布特征及生态风险评价

Distribution characteristics and ecological risk evaluation of heavy metals in grassland soils in the east-central region of Inner Mongolia

为探究内蒙古中东部地区草原土壤重金属污染特征及生态风险状况,采集四子王旗、苏尼特右旗、商都、锡林浩特、西乌旗、新巴尔虎左旗、鄂温克族自治旗等地区土壤,对其中重金属元素(Cd、Cr、As、Zn、Pb和Cu)的全量和有效态含量进行测定,运用空间插值法分析内蒙古草原土壤中重金属含量的空间分异特征;同时采用地累积指数法、潜在生态风险指数法和风险评估指数法对重金属元素的生态风险进行了评价.结果表明,内蒙古中东部地区草原土壤全量重金属元素Cr、Cu、Pb的平均含量相对较低,而Cd、As和Zn全量的均值分别是背景值的3.58倍、1.53倍和1.98倍.地累积指数评价结果显示Cd的污染程度最高,其它元素污染程度相对较低.潜在生态风险指数评价结果显示Cd为研究区土壤中最主要的潜在生态危害因子,其次是As,其它元素则处于低生态危害.风险评估指数法结果显示,研究区土壤中有效态重金属占重金属总量的百分含量不到10%,说明研究区土壤中重金属元素的生物可利用性较低,对环境构成的风险也相对较低.综合来看,研究区土壤中Cd元素存在一定的潜在风险,需引起有关部门高度重视,加大监测力度.

To investigate the characteristics and ecological risk of heavy metal pollution in grassland soils in the east-central region of Inner Mongolia,soils were collected from Siziwang Banner,Sunit Right Banner,Shangdu,Xilinhot,Xiwuqi,Xinbahuzuo Banner and Ewenke Autonomous Banner.The total and available content of heavy metals(Cd,Cr,As,Zn,Pb and Cu)in soils were determined,the spatial variation characteristics of heavy metal contents in grassland soils of Inner Mongolia were analyzed using spatial interpolation method.The ecological risks of heavy metals were also evaluated using the geological accumulation index,the potential ecological risk index and the risk assessment index.The results showed that the average total contents of Cr,Cu and Pb in the grassland soil of the east-central region of Inner Mongolia were relatively low,while the average total contents of Cd,As and Zn were 3.58,1.53 and 1.98 times of the background values respectively.The results of the evaluation of the ground accumulation index show that the pollution level of Cd is the highest,while those of other elements is relatively low.The evaluation results of potential ecological risk index showed that Cd was the most important potential ecological hazard factor in the soils of the study area,followed by As,and the other elements were in low ecological hazard.The results of risk assessment index method showed that the available heavy metals in the soils of the study area accounted for less than 10%of the total heavy metals content,indicating that the bioavailability of heavy metal elements in the soils of the study area is low and the risk posed to the environment is relatively low.In general,there is a certain potential risk of Cd in the soil in the study area,which needs to be highly valued by relevant departments and strengthened monitoring.