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针对重金属铬(Cr)污染严重的现象,基于简单的二层非完全混合模型,将降雨时农田土壤与积水整个系统分为混合区及混合区以下两个部分,根据水量平衡原理和溶质质量守恒定律,研究土壤在非线性Langmuir吸附条件下,吸附性溶质Cr(VI)的径流流失规律。试验模拟的田间地表径流是由降雨引起的,根据降雨期间土壤与雨水相互作用情况,将降雨过程分为4个阶段分别求解进行研究。利用室内模拟降雨-径流试验所得数据进行模拟计算,并通过敏感性分析和模型参数对径流流失量的影响分析,阐明模型参数对土壤中吸附性溶质径流流失规律的影响。研究结果表明:此二层非完全混合模型能预测土壤在非线性Langmuir吸附条件下,吸附性溶质Cr(VI)的径流流失规律。该模型对入渗水溶质与土壤混合层溶质之间的非完全混合系数γ非常敏感,对土壤混合层溶质与地表积水-径流水溶质之间的非完全混合系数α不敏感,对Langmuir吸附方程中的参数B、C也不敏感。其中γ和α对模拟径流流失过程的影响主要作用于降雨前期,而Langmuir吸附方程中的参数B对模拟过程的影响作用于降雨前期,C也主要作用于降雨前期,但对后期的影响比其他参数更大。试验数据显示地表径流中溶质含量很低,说明该次试验中混合层溶质进入地表积水-径流层量很少,而模拟α值很小,与实际情况吻合,同时也说明,土壤中流失的污染物重金属Cr(VI)大多存在于地下排水中。
Aiming at the serious pollution of heavy metal chromium (Cr), based on a simple two-layer incomplete mixing model, the whole system of soil and water accumulation in farmland during rainfall is divided into the following two parts: mixing area and mixing area. According to the water balance principle and solute quality The law of conservation was used to study the runoff loss of adsorbed solute Cr (VI) under non-linear Langmuir adsorption conditions. The surface runoff simulated by the experiment is caused by rainfall. According to the interaction between soil and rainwater during the rainfall, the rainfall process is divided into four stages and solved separately. The simulated data from indoor simulated rainfall-runoff experiments were used to simulate the effects of model parameters on the runoff loss of solute in the soil through sensitivity analysis and model parameters. The results show that this two-layer incomplete mixed model can predict the runoff loss of adsorptive solute Cr (VI) under non-linear Langmuir adsorption conditions. The model is very sensitive to the incomplete mixing coefficient γ between the infiltration aqueous solute and the soil mixed layer solute. It is not sensitive to the incomplete mixing coefficient α between the soil mixed layer solute and the surface water-runoff aqueous solute. The Langmuir adsorption The parameters in the equation B, C are not sensitive. The effects of γ and α on the simulated runoff loss mainly play a role in the pre-rainfall period. However, the influence of the parameter B in the Langmuir adsorption equation on the simulation process is mainly in the pre-rainfall period, while the C effect mainly on the pre- More parameters. The experimental data show that the solute content of the surface runoff is very low, indicating that the mixed layer solute enters the surface water in this experiment - the amount of runoff is very small and the simulated α is small, which is consistent with the actual situation. It also shows that the loss of Pollutants Most of the heavy metals Cr (VI) exist in underground drainage.