【作者】 袁涛；

【导师】 韩宝平；

【作者基本信息】 中国矿业大学 ， 环境科学， 2014， 博士

【摘要】 七里沟水源地作为徐州市南区的主要供水水源地，面积约120余km2，区内岩溶地下水近年受到了四氯化碳污染。2001年以来，课题组在两项国家自然科学基金资助下，选取该地四氯化碳污染区作为研究区域，综合采用环境与水文地质调查、地球物理勘探、现场采样监测、场地示踪试验等多种方法，依据岩溶双重含水介质理论，对岩溶地下水流场与四氯化碳的运移规律进行了系统研究。研究区内共设置水位观测井80余口，四氯化碳浓度年度普测井35－40口，四氯化碳浓度常规监测井21口，根据课题组10余年来获得的3000多组监测数据，并结合地质、水文地质与勘探钻孔资料，揭示了该区上覆为松散层和下伏为岩溶含水层的二元水文地质结构特征，建立了松散层中四氯化碳垂向迁移模型、岩溶双重含水介质流场模型和四氯化碳运移模型，经实测数据验证准确后，对未来四氯化碳的污染状况进行了预测，取得下列成果：(1)系统研究了徐州市岩溶含水系统特征，将其划分为四种岩溶含水介质类型。研究区位于徐州市南部，主要含水介质类型为：第四系孔隙含水岩组和碳酸盐岩类裂隙溶洞含水岩组。根据徐州市多年岩溶水开采情况，分析了岩溶含水层的补给方式和影响因素，构建了徐州市岩溶地下水循环系统；(2)研究区岩溶发育和岩溶水运移具有明显的非均质性，除普通岩溶孔隙特征之外，还存在发育的溶洞和裂隙等管道介质；根据54口钻井资料及十几组岩芯溶蚀情况，调查了区内地下岩溶发育状况，尤其是裂隙、大溶洞等管道介质在垂向上的分布特征；通过现场示踪试验深入研究了岩溶含水介质的双重发育特征，确定了岩溶管道介质的空间分布位置；(3)运用DRASTIC模型对研究区地下水脆弱性进行了评价，根据7项评价因子分配权重并评分计算，划分地下水脆弱性等级。结果显示，研究区地下水脆弱性程度较高，60%以上面积属于较易污染范畴，农药西厂作为七里沟盆地四氯化碳污染源，正位于区内南部极易受污染区域；(4)采集污染源区松散层土样，进行了实验室土柱下渗实验，得出相关参数并运用Hydrus-1D软件研究了四氯化碳在松散层中的迁移规律；根据污染源区钻孔勘探数据，模拟计算污染源区四氯化碳从排污渠通过上覆松散层下渗进入岩溶含水层的浓度。结果显示，污染源区四氯化碳在松散层底部的平均渗出浓度为2773.6μg/L，这一数值即是岩溶含水层中的初始浓度；(5)依据岩溶双重含水介质理论，以2004年4月至2012年4月40余口典型井的水位监测数据为基础，建立了研究区岩溶地下水运动的的双重介质数学模型。运用ModelMuse软件，引入双重介质中水力交换系数，分别将双重介质的渗透系数分区，选取2004年4月至2005年4月为模型识别期，2005年4月至2012年4月为模型验证期，建立了岩溶双重含水介质流场模型。根据典型井的水位对比曲线得知，误差区间为0.27m－0.43m，显示所建模型较为可靠；(6)选取2004年8月至2012年4月期间21口常规监测井，40口普测井的四氯化碳连续监测数据，构建了研究区四氯化碳污染的运移模型。经验证得知，研究区四氯化碳浓度平均相对误差范围为11.4%－16.7%，与实际监测数据拟合较好，模型较为可靠。在此基础上预测了2015、2018、2022和2025年的四氯化碳污染状况，结果显示，随着农药厂的搬迁以及南区部分井点的抽水强排治理工作，区内四氯化碳整体趋势为：污染浓度逐年降低，污染羽范围逐步缩减，污染羽南部、北部和中部典型井中四氯化碳衰减速率依次递减，且中部和北部污染羽将于2022年和2025年消失，预测结果可为下一步水源地的污染治理和水资源利用规划提供理论依据。更多还原

【Abstract】 Qiligou is the main water supply source located in South Xuzhou. Karst groundwater inthis area, with area of120km2, is severely contaminated by CCl4. Since2001, we conductedlocal environment and hydrogeological investigation, explored local physical geography,measured field data, performed tracing experiments, and studied transport of CCl4based onduel-conductivity medium theory under the supporting of National Science Foundation ofChina. Amount of80research wells were studied, among which water level and CCl4concentration of35－40wells were measured four times per year, CCl4concentration of21wells were measured every month. Based on3000field data in10years, local hydrogeologyinformation, and drilling data, dual structure of unconsolidated formation and karst aquiferwas established. Transport model of CCl4and dual-conductivity medium flow model werebuilt, as well as, future contamination by CCl4was forecasted. The research is meaningful andvaluable both for theory development and engineering application. The results are showedbelow:(1) Karst aquifer medium characteristic in Xuzhou was investigated and divided into4types. The reaseach area is located in the south of city, which has two kinds of aquifermedium characteristics: Quaternary porous medium and Carbonate fracture medium. Inaddition, the supply way and affecting factors was analyzed to construct karst groundwatercircle system.(2) Karst and karst water transport in studied area has significant heterogeneity,excepting the common features of karst porosity, there still exist developed cave, dissolvedpores, cracks, and other conduit media. According to54drilling data and core dissolutioninformation, karst development was investigated, especially for the cracks and large caves’distribution in vertical direction. Double-development characteristic of karst aquifer mediumwas studied via field-scale tracing experiments, and location of karst conduit medium wasidentified as a main migration pathway for both groundwater and CCl4.(3) According to the DRASTIC model on groundwater vulnerable assessment, sevenfactors were used to evaluate weight, calculate and grade the contaminated divisions. Theresults show that, the entire research area was being in high vulnerable condition; more than60%of the area was easy to be contaminated. Unfortunately, CCl4contamination source, westinsecticide factory, was located in the high susceptible contamination area.(4) The loose layer soil samples were collected to conducted lab-scale infiltration experiments. By using Hydrus-1D software, we verified transport of CCl4in loose layer andsimulated CCl4concentration in karst aquifer from contamination source and bypass looselayer, according drilling data of contamination area. The results showed the average CCl4leaking concentration at the bottom of loose layer was2773.6μg/L, which was the initialconcentration in karst aquifer.(5) Dual-conductivity mathematical model was built based on dual-conductivity theoryand water level data for more than40wells from April2004to April2012; hydro-exchangeparameter was introduced, and dual-medium was divided by ModelMuse software;dual-medium flow model was built according to model identification period, from April2004to April2005, as well as model verification period, from April2005to April2012. The errorwas between0.27m－0.43m, which indicated the reliability of the model by comparing withwater level in typical wells.(6) Research area CCl4transport model was established based on continuous monitordata for40general wells and21regular wells from August2004to April2012. The relativeerror was between11.4%－16.7%for CCl4concentration, which indicated the reliability ofthe model by comparing with real data. CCl4concentration in2015,2018,2022, and2025wasforecasted, which showed contamination concentration will decline over time, contaminationplume will decrease, and the southern typical well shows the highest decay rate of CCl4,followed by northern and middle ones. The contamination plumes in the middle and northernarea which will be disappeared by2022and2025due to the closing of pesticide factory andwater regulation and control. The forecasting results will provide the technical guide for watersource area pollution control and water resource planning.更多还原