【摘要】 以燃煤电厂较为集中的鄂尔多斯为研究区域,选取目前易被忽视的2种电厂污染物氨氮、氟离子作为污染因子,探究此类污染物在区域内非饱和带土壤细砂、砂质粉土层的运移规律。通过室内实验、Hydrus-1D软件建立模型进行模拟预测,以获得污染物垂向分布规律。由动态淋滤实验可知:污染物在细砂中的完全穿透时间小于砂质粉土;Hydrus-1D模拟值与实测值相关性较好,相关系数为0. 950～0. 996;模型校准后,获得用于模拟预测的最佳参数值,细砂土与砂质粉土弥散度α分别为0. 937,0. 75 cm;氨氮在细砂土与砂质粉土中溶质反应参数Kd、Nu分别为2. 5 mg/m L,50. 9 m L/mg,氟离子分别为4. 83 mg/m L,28. 91 m L/mg;模拟持续排放污染物情况可知,短时间内可穿透10 m厚细砂土层,砂质粉土层对污染物截留能力相对较优;高浓度污染物一次性入渗时,高浓度污染物一次性入渗时,污染物10天时穿透10 m砂土层,180 d时氨氮污染物穿透砂质粉土层,氟化物未能穿透。模拟预测可判断污染物是否能够穿透非饱和带进入地下水取决于污染物浓度、土层质地与厚度、污染物排放时间等因素的共同影响。更多还原

【Abstract】 For a long time,coal-fired power plants provide strong support for China’s economic development,but also bring serious environmental pollution problems. The soil in coal-fined power plant also possess a risk of contamination to the groundwater environment. The sewage and solid waste generated by the power plants will be leached by water to produce leaching filtrate. Infiltration into the unsaturated zone and even into the groundwater will produce a series of environmental geological problems. Therefore,the Ordos area,with coal-fired power plants concentrated,was taken as the research area,and the migration law of pollutants generated in a power plants in the soil layer was studied. The ammonia nitrogen and fluoride ions of the two power plants were selected as the pollution factors. We investigated the migration of such pollutants in the fine sand and sandy silt soil in the unsaturated zone. Through the experiment,Hydrus-1 D software was used to establish the model,simulated prediction to obtain the vertical space change of pollutants,to provid scientific basis for the environmental impact assessment of coal-fired power plants. The dynamic leaching experiment showed that the complete penetration time of pollutants in fine sand was less than that of sandy silt. The correlation between the value and the experimental measurement was intensive,with correlation coefficients between 0. 950 and 0. 996. After the model calibration,the optimal parameter value for the simulation prediction was obtained. The dispersion α of the fine sand and sandy silt was 0. 937 cm and 0. 75 cm. The solute reaction parameters Kdand Nuof the ammonia nitrogen in the fine sand and sandy silt were 2. 5,50. 9 m L/mg,and the fluoride ion were 4. 83 mg/m L and 28. 91 m L/cm,respectively. Simulation of persistent emission pollutants showed that the migration rate of pollutants in fine sand layer was relatively larger,and could penetrate 10 meter-thick soil layer in a short time,while the silt layer had relatively good ability to intercept pollutants. When the high-concentration pollutants were infiltrated at one time,the pollutants penetrate 10 m of sand layer at 10 days,and the ammonia-nitrogen pollutants penetrated the sandy silt layer at 180 days,and the fluoride failed to penetrate. The penetration capacity of a pollutant in the unsaturated zone into the groundwater depended on pollutant concentration,soil texture and thickness,and pollutant discharge time.更多还原