浑河中游1,2-DCA在地下水中运移规律的模拟分析

为研究有机组分在地下水中的运移规律及影响因素,并预测水质的破坏程度,利用数值模拟方法建立浑河中游区域特征有机污染组分1,2-DCA(1,2-二氯乙烷)的溶质运移模型,分析1,2-DCA在浑河中游地下水中的运移规律,并预测了其对地下水水质的影响. 细河与浑河中1,2-DCA的补给浓度(以ρ计)分别为4.50和6.40μg/L,预测期为10a,在运移模型中考虑弥散、吸附、降解作用的影响. 模拟结果显示,预测期内1,2-DCA在细河污染区的最大影响面积为1.80km2,峰值浓度(以ρ计)为3.50μg/L,污染物向北西方向运移；在浑河污染区的最大影响面积为3.78km2,峰值浓度为5.00μg/L,污染物向西南方向运移,表明污染物对地下水水质影响程度较低. 预测初期的200d内,吸附及生物降解的共同作用使细河、浑河污染晕中心的ρ(1,2-DCA)分别下降了0.12、0.10μg/L；随后,对流-弥散作用成为溶质运移的主要驱动力,并且使1,2-DCA的污染程度持续增强；黏土对1,2-DCA的运移具有阻滞作用,1,2-DCA在细河污染晕的扩散幅度略低于浑河. 

Migration Simulation Analysis of 1,2-DCA in the Groundwater of the Middle Reaches of Hunhe River

Serious organic contamination was surveyed in the middle reaches of Hunhe River by assessing the alluvial fan for groundwater pollution. In order to investigate the migration regularity and impact factors of organic contaminants in the regional groundwater and to predict the degree of water pollution, the migration model of characteristic components of 1,2-dichloroethane (1,2-DCA) was established by numerical simulation method. We analyzed the migration regularity of 1,2-DCA in the groundwater of the middle reaches of Hunhe River and calculated the influence of water quality by 1,2-DCA. For the model, the initial recharge concentration of 1,2-DCA in Xihe River and Hunhe River were 4.50and 6.40μg/L, respectively, with a predicted period of 10years, considering the effect of diffusion, adsorption and degradation in numerical simulation. The results indicated that the maximum impacted area by 1,2-DCA in Xihe River was 1.80km2, with maximum value of 3.50μg/L in the predicted period, while the impacted area in Hunhe River pollution zone was 3.78km2, with maximum value of 5.00μg/L. The results showed a minor degree of damage to the regional groundwater quality. During the first 200days of the predicted period, the adsorption and biodegradation reduced the concentrations of 1,2-DCA in the contamination halo centers in Xihe and Hunhe rivers by 0.12and 0.10μg/L, respectively. Then, with the convection-dispersion as driving force for migration, the contamination of 1,2-DCA increased continuously. Due to the retardation of the cohesive soil to the migration of 1,2-DCA, the diffusion of the contaminants in Xihe River may be slower than that in Hunhe River.