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[目的]研究莠去津在原状土柱中的运移,判断其在土壤中的移动性及其对地下水的危害性。[方法]在相隔依次为6.5、8.5和6.5m的A、B、C、D4个地点的20～73cm深处,采集直径为25cm的原状土柱。土柱上端用马氏瓶供水,进水水头稳定保持在土柱土壤表面上2cm处。土柱底部以透水金属盘承托,金属盘中心为出水口。用量为大约10倍孔隙容积的去离子水饱和土柱,随后向其投放含不同质量浓度的莠去津和溴化钾溶液,用溴化钾作示踪剂来标记土柱中水分的运动。用CXTFIT软件模拟莠去津的穿透曲线、率定吸附和降解参数,并与批次试验所得相应参数进行比较。[结果]莠去津到达约53cm深土柱底部的浓度可达到初始浓度的20%～42%,说明其弱吸附和弱降解使得其污染浅层地下水的可能性很大。土壤的渗透性影响土壤水分运动,是影响莠去津运移的重要因素。CXTFIT的两区和两点模型均能较好地模拟莠去津的穿透曲线,4个原状土柱中平均不可动水体含量约为7%。两点模型拟合效果更好,主要表现在穿透曲线的尾部。据此推测莠去津的非平衡运移部分可描述为化学非平衡。[结论]土柱试验和批次试验得到的吸附参数和降解参数都存在空间差异,但是基本处于同一数量级。因此,如果试验条件控制得当,可以结合土柱试验和批次试验的结果进行大尺度莠去津运移模拟和预报。
[Objective] The study aimed to study the migration of atrazine in intact soil column and to determine its mobility in soil and its harmfulness to groundwater. [Method] The undisturbed soil column with a diameter of 25cm was collected at depths of 20 ~ 73cm in A, B, C and D locations of 6.5, 6.5 and 6.5m. The top of soil column with Markov bottle water supply, water inlet steady head 2cm at soil column soil surface. Soil column to the bottom of the metal tray supporting the metal plate center for the outlet. The soil was saturated with deionized water at a pore volume of about 10 times and then treated with different concentrations of atrazine and potassium bromide solution. Potassium bromide was used as a tracer to mark the movement of water in the soil column. The breakthrough curve of atrazine was simulated by CXTFIT software, and the parameters of adsorption and degradation were determined and compared with the corresponding parameters of the batch test. [Result] Atrazine reached the bottom of about 53 cm deep soil column concentration of 20% to 42% of the initial concentration, indicating that its weak adsorption and weak degradation make it very likely contaminated shallow groundwater. Soil permeability affects soil moisture movement and is an important factor affecting atrazine transport. CXTFIT two-zone and two-point model can better simulate the penetration curve of atrazine, the average content of 4 immobile water in the four original soil columns is about 7%. Two-point model fitting better, mainly in the tail of the penetration curve. It is speculated that atrazine part of the non-equilibrium migration can be described as chemical non-equilibrium. [Conclusion] There were spatial differences between adsorption parameters and degradation parameters obtained by soil column test and batch test, but they were basically in the same order of magnitude. Therefore, if the test conditions are properly controlled, the large-scale atrazine transport simulation and prediction can be combined with the results of soil column test and batch test.