再生水入渗过程中抗生素的迁移规律及机理研究

The artificial recharge has been proved to be a potential disturbance to the hydrodynamic and hydrochemical fields in groundwater system, which may even lead to the pollution of groundwater. Therefore, how to guarantee the security and stability of the groundwater system during the process of artificial recharge have been considered as the key issue in current studies.. This study will focus on the migration rules and mechanisms of antibiotics in the infiltration process. Modern testing technologies, microstructure characterization techniques, indoor static experiments, sand column simulative experiments and comprehensive analysis will be carried out in three different scales (micro, lab and field scale). Thus, problems such as the distribution and occurrence of typical antibiotics in recharge aquifer medium, the change rules of permeability caused by the variation of aquifer medium structure, the influence of hydrodynamic and hydrochemical conditions, as well as the influence of colloid on the migration and transformation of antibiotics are expected to be clarified. In addition, the main controlling factor of antibiotics migration will be identified, and the internal mechanisms of antibiotics-mineral surface interaction will be revealed in micro structure. Combined with the analysis of aquifer structure and variations of permeability in temporal and spatial scales, the characteristic and risk of antibiotics-microelements-colloids migration in groundwater under artificial recharge will be forecasted. This study will deeply understand the migration rules and mechanisms of antibiotics in the infiltration process, providing technical supports for both controlling of organic contaminants in groundwater and guarantee of drinking water safety.

人工回灌会扰动地下水水动力场和水化学场，甚至会污染地下水。如何保障人工回灌条件下地下水环境质量的安全稳定性，已成为当前地下水理论与技术研究所面临的关键问题。.本项目拟聚焦入渗过程中抗生素类有机污染物的迁移特征及机理展开研究,从微观、实验室、场地三个尺度，以现代测试技术、微观结构表征技术、室内静态实验、砂柱入渗实验、原位模拟实验和综合分析等为手段，分析代表性抗生素在回灌含水介质中的分布与赋存状态，研究回灌激发下含水介质结构变化引起的渗透率的变化规律，探索水动力、水化学条件变化和胶体促使下抗生素的迁移规律，识别影响有机污染物迁移的主控因素，从微观结构上揭示抗生素与含水介质界面作用的内在机制。结合含水层结构、渗透性时空变化等，预测回灌过程中抗生素-微量元素-胶体共迁移的特征和污染风险。深化对回灌条件下地下水中有机污染物的迁移规律的理解和认识，为地下水中有机污染物控制和饮水安全提供技术支撑。

本项目以再生水中四环素类、喹诺酮类、磺胺类和氨基糖苷类抗生素污染物为研究对象，研究了含水层介质、堵塞实验导致的渗透规律，分析抗生素在含水层介质的迁移规律及其因素影响，模拟抗生素-微量元素-胶体共迁移过程，通过表征和数值模拟揭示回灌条件下污染物相互作用机理，获得以下主要结论：.1.三种介质渗透性大小依次为中砂（0.200cm/s）> 细砂（0.020cm/s）> 粉砂（0.008cm/s）；中砂：细砂：粉砂=3:2:1和1:2:3的渗透系数分别为0.057cm/s和0.027cm/s，渗透系数衰减率分别为54.55%和68%。无论物理堵塞还是生物堵塞，均易发生在砂柱上部浅层，粗砂越靠上，细砂越靠下，回灌越不易堵塞。.2. OTC与SD分布关系为水相>悬浮相，分配系数Kd为OTC>SD，说明水体中四环素类抗生素较磺胺类更容易分布到悬浮相。实验和紫外-可见光谱图和三维荧光分析均表明HA 对OTC和SD在水悬浮相的分布均有显著的促进作用。温度对HA、HA-OTC和HA-SD体系的紫外光谱特征不敏感，中性偏碱性环境可以提高HA对抗生素在悬浮相中的分布促进作用。离子强度增加弱化HA对抗生素在水体悬浮相中分布的促进作用..3．铜氨络离子、刚果红对氧氟沙星和环丙沙星为静态猝灭。与Cu2+相比，铜氨络离子与FLQs（氧氟沙星和环丙沙星）的荧光猝灭能力更强。三元体系表明：Cu2+对FLQs-刚果红体系均有荧光猝灭作用，推导出共振瑞利散射与Cu2+浓度之间的关系。共振瑞利散射法测定三种污染物之间相互作用的稳定性、灵敏度更高，适用性更强。.4. CR分别与NEO（GEN）通过疏水作用力结合，形成1:1的二元离子缔合物，酸性条件下，两个体系的共振瑞利散射强度明显增强。金属离子对体系共振瑞利散射强度的影响：二价＞三价＞一价。加入阳离子表面活性剂比非离子表面活性剂聚乙二醇，体系的共振瑞利散射强度增加的快；加入阴离子表面活性剂十二烷基苯磺酸钠后，散射强度降低。.5. 建立包气带溶质运移模型，无论是连续泄漏还是瞬时泄漏，土霉素进入含水层的速度都很快，大约 200天，浓度稳定在 0.225mg/L。