铬在含水介质中的迁移及释放规律

根据天津某铬渣堆周边地区的污染情况和水文地质条件,选取该区域3种典型含水介质(黏土、粉质黏土、粉土)填充土柱,开展室内土柱淋滤实验,研究铬在含水介质中的迁移及释放规律。铬溶液淋滤实验表明,Cr(VI)在粉土中的迁移速率最快,粉质黏土中次之,黏土中最慢。清水淋滤实验表明,吸附在含水介质中的铬会在清水淋滤作用下解吸并重新释放到地下水中,从而造成地下水再次污染。根据土柱实验结果获得铬在黏土、粉质黏土和粉土中的弥散系数分别为1.87×10~(-4)m2d~(-1)、7.49×10~(-4)m2d~(-1)和1.17×10~(-4)m2d~(-1),渗透系数分别为8.60×10-6cm s~(-1)、2.14×10-5cm s~(-1)和1.34×10-5cm s~(-1),为模拟铬在含水介质中的迁移模型提供实测参数,进而为地下水中铬污染的控制与防治提供理论参考。

Migration and Release of Chromium in Underground Aquifer Media

According to the pollution and hydrogeological conditions in a chromium (Cr) slag heap in Tianjin,three typical aquifer media (clay,silty clay and silt) were selected to fill soil columns,and dynamic soil column leaching indoor experiments were carried out to study the migration and releasing of Cr in aquifer media.Cr solution leaching results showed that the Cr (Ⅵ) migrtion rates were the fastest in the silt,followed by in the silty clay,and then in the clay aquifer media,Water leaching experiments showed that Cr,which was adsorbed in aquifer media,would be desorbed and released into groundwater by water leaching,resulting in the secondary pollution of groundwater.Based on soil column experimental results,the dispersion coefficients and permeability coefficients of Cr in clay,silty clay and silt were 1.87 × 10-4 m2 d-1,7.49 × 10-4 m2 d-1,1.17 × 10-4 m2 d-1 and 8.60 × 10-6 cm s-1,2.14 × 10-5 cm s-1,1.34 × 10-5 cm s-1,respectively,which would provide the measured parameters for the Cr migration model in aquifer media,and then the theoretical reference for control and prevention of Cr pollution in underground water.