区域土壤背景重金属Cd环境容量分析与预测

Environmental Capacity Analysis and Prediction of Heavy Metal Cd in Regional Soil Background Environmental Capacity

文章通过对研究区域原“十一五”期间土壤背景值调查的监测点位进行复采复测,测定监测点位表层土壤重金属含量;根据区域土壤背景值、风险筛选值及重金属Cd的监测结果,分别计算区域表层土壤重金属Cd平均年静态环境容量和平均年动态容量;以监测结果获得年(2019年)为起始观察年,分析区域表层土壤重金属Cd环境容量随时间变化趋势,并对2030年、2040年、2050年区域表层土壤重金属Cd的累积残留情况进行预测。结果表明:研究区域监测点位表层土壤重金属Cd的含量范围为0.05~8.97 mg/kg,平均值为0.29 mg/kg,约16.8%监测点位超出风险筛选值;研究区域监测点位表层土壤重金属Cd静态总环境容量和现存总环境容量分别约为0.349 kg/hm^(2)和0.185 kg/hm^(2),约58.7%监测点位属高容量区,基本未受污染;2030年、2040年、2050年研究区域土壤重金属Cd的预测残留量平均值分别约为0.363、0.401、0.424 mg/kg。研究区域表层土壤环境质量整体良好,但仍然有一定比例的监测点位属于低容量区,已经受到一定程度的外源污染输入影响,需通过加强外源污染输入防治措施,逐渐改善当前研究区域监测点位表层土壤重金属Cd环境容量低的现状。

The heavy metal content was remeasured by means of re-sampling and re-measuring the monitoring points of the regional soil background values during the original“Eleventh Five-Year Plan”period.The average annual static environmen⁃tal capacity and average annual dynamic capacity of heavy metal Cd in the regional surface soil were calculated according to the soil background value,risk screening value and monitoring results.The year(2019)of obtained monitoring results is taken as the starting observation year.The change trend was analyzed with time of heavy metal Cd environmental capacity in region⁃al surface soil,and the accumulation and residue were predicted of heavy metal Cd in the regional surface soil in 2030,2040 and 2050.The results show that the content of heavy metal Cd ranged from 0.05 mg/kg to 8.97 mg/kg of monitoring points in the regional surface soil,and the average value was 0.29 mg/kg.There was about 16.8%of monitoring points which exceeded the risk screening value of heavy metal Cd in the regional surface soil.The total static and existing environmental capacities were about 0.349 kg/hm^(2)and 0.185 kg/hm^(2)of heavy metal Cd at the monitoring points in the regional surface soil,respective⁃ly.There was about 58.7%of monitoring points which belonged to high capacity areas,and uncontaminated.The average pre⁃dicted residual amount will to be about 0.363 mg/kg,0.401 mg/kg and 0.424 mg/kg of heavy metal Cd in the regional surface soil in 2030,2040 and 2050 respectively.The regional surface soil environment quality overall was good in the study area.However,there were still a certain proportion of monitoring points belonging to low capacity area,and it has been affected by the input of exogenous pollution to a certain extent.Therefore,it is necessary to urgent to strengthen measures prevent the ex⁃ogenous pollution input,in order to gradually improving the current situation of low environmental capacity of heavy metal Cd at the monitoring points in regional surface soil of study area.