研究报告
陈卓,刘文晓,张丹,吴志远,夏天翔.典型化工废渣污染土壤中汞的空间分布规律研究[J].环境科学学报,2022,42(4):422-431
典型化工废渣污染土壤中汞的空间分布规律研究
- Spatial distribution and vertical migration of mercury in soil contaminated by chemical waste residues
- 基金项目:国家重点研发计划专项课题(No.2018YFC1801006)
- 陈卓
- 北京市环境保护科学研究院,污染场地风险模拟与修复北京市重点实验室,北京 100037;国家城市环境污染控制工程技术研究中心,北京 100037
- 刘文晓
- 北京市环境保护科学研究院,污染场地风险模拟与修复北京市重点实验室,北京 100037;国家城市环境污染控制工程技术研究中心,北京 100037
- 张丹
- 北京市环境保护科学研究院,污染场地风险模拟与修复北京市重点实验室,北京 100037;国家城市环境污染控制工程技术研究中心,北京 100037
- 吴志远
- 北京市环境保护科学研究院,污染场地风险模拟与修复北京市重点实验室,北京 100037;国家城市环境污染控制工程技术研究中心,北京 100037
- 夏天翔
- 北京市环境保护科学研究院,污染场地风险模拟与修复北京市重点实验室,北京 100037;国家城市环境污染控制工程技术研究中心,北京 100037
- 摘要:为阐明氯碱厂废渣堆积遗留场地中汞的空间分布规律,在某典型场地设置313个表层(0.5 m)、79个深层(0.5~13.5 m)土壤采样点位及6个地下水采样点位,分析所有土壤样品的总汞浓度、表层土壤的理化性质及地下水总汞浓度.结果显示:①该场地土壤汞污染严重,313个表层土壤样点汞检出浓度为0.002~579.14 mg·kg-1,平均为8.43 mg·kg-1,高于《土壤环境质量 农用地土壤污染风险管控标准(试行)》中的风险管控值(6 mg·kg-1).反距离权重法(IDW)及自然邻域法(NNI)对该场地的汞水平浓度分布的插值更为准确.②79个深层点位土壤垂向检测结果显示,土壤上层区域(0.5、1.5、2.5 m)汞污染浓度更高,3个深度层的汞浓度平均值分别为7.3、5.5、3.1 mg·kg-1,2.5 m以下7个深度层的汞浓度平均值仅为(1.02±0.15) mg·kg-1;汞垂向富集因子为0.4~32,大多数(66%)采样点位汞的富集因子(EF)随着土壤深度增加显著下降.③汞的垂向迁移率随土壤汞浓度的增加呈下降趋势,较高的土壤有机质能显著抑制汞的垂向迁移,较高的土壤pH(>10.5)能显著促进汞的垂向迁移.④场地地下水受到一定汞污染,污染程度与该点位土壤污染程度呈显著正相关,三相平衡模型对于地下水汞的预测值低于实测值,预测值与实测值的比值为1∶2.总体而言,该场地土壤中汞污染严重,但垂向迁移能力有限,研究结果有助于进一步阐明土壤中汞的迁移转化机制,为类似场地的污染调查及治理修复工作提供科学依据.
- Abstract:To clarify the spatial distribution characteristics of mercury in chlor-alkali chemical plant site and the risk of groundwater pollution,313 surface layers(0.5 m),79 deep layers (0.5~13.5 m)soil sampling points,and 6 groundwater were set up on the site.The total mercury concentration of all soil samples,the physical and chemical properties of the surface soil and the mercury concentration of groundwater were tested. Results showed: ①The site has serious and unevenly distributed mercury pollution,and the concentration of 313 surface mercury range from 0.002~579.14 mg·kg-1, the average is 8.43 mg·kg-1,the coefficient of variation is 4.54.The Inverse distance weighting(IDW) and Natural Neighbor Interpolation(NNI) have more accurate interpolation effects on the mercury concentration distribution of the site.②The most serious mercury pollution still exists in the upper layer of the soil (0.5,1.5,2.5 m), and the average mercury concentration in the three depth layers is 7.3 mg·kg-1, 5.5 mg·kg-1, 3.1 mg·kg-1, below 2.5 m, the average mercury concentration is only (1.02±0.15) mg·kg-1; for the deep layer sampling points,the mercury vertical enrichment factor range from 0.4~32, most (66%) points’mercury enrichment factor (EF) decreased significantly with the increase of soil depth.③The migration rate of Hg decrease with the increase of surface mercury concentration,high organic matter content can significantly inhibit the vertical migration of Hg,high pH can significantly promote the migration of Hg.④The groundwater is little polluted by mercury,and the pollution degree is significantly positively correlated with the soil pollution,the predicted value of the three-phase equilibrium model for groundwater mercury is lower than the measured value,the rate is 1∶2.Above all,the vertical migration capacity of mercury in the site is limited,the results of the study are helpful to further characterize the migration law of high-concentration mercury in the soil and provide a scientific basis for the governance and restoration of similar sites.