人工回灌含水层氧化还原分带与微生物堵塞动态耦合关系与机制

Clogging is an important problem restricting wide implementation and application of managed aquifer recharge (MAR). However, microbial activity is one of critical factors. During the MAR process, redox zonation can be formed along with flow, and the induced variation in redox environment could affect microbial activity, and further bioclogging process. At present, most studies of bioclogging mainly focused on rich oxygen environment. The dynamic coupling relationship between redox zonation and bioclogging during the MAR process is still unclear. In this study, a series of laboratory percolation experiments will been conducted to simulated artificial recharge. We mainly focus on the characterization in redox zonation in aquifers under different redox conditions, and the process of bioclogging in each redox zonation. By using analytical chemistry, electron microscopy, and molecular biology techniques, the bacterial growth, metabolism, and community characterization in different redox zones were studied. The objectives were to analyze main controlling factors in redox zones, and to reveal mechanism of bioclogging, and to clarify the dynamic coupling relationship and mechanism between redox zonation and bioclogging in the MAR process.

含水层堵塞是制约人工回灌工程实施和广泛应用的重要难题，而微生物活动是导致含水层堵塞的重要成因之一。人工回灌过程中沿渗流路径可形成氧化还原分带，由此产生的氧化还原环境差异会影响含水层的微生物活动，进而影响堵塞速率和程度，反过来堵塞过程中微生物代谢活性和群落的变化又对氧化还原分带的形成具有潜在影响。目前，针对含水层微生物堵塞的研究多以富氧环境为主，对于氧化还原分带与微生物堵塞之间的动态耦合关系尚不清楚。本项目拟开展室内一维渗流试验，模拟人工回灌含水层过程，研究不同氧化还原条件含水层中氧化还原分带特征以及各分带上微生物堵塞过程；利用分析化学技术、电镜技术以及分子生物学技术，研究不同氧化还原分带上细菌的生长和代谢规律及其群落演化特征，分析各分带堵塞主控因素，揭示微生物堵塞内在机理，最终阐明氧化还原分带与微生物堵塞的动态耦合关系与内在机制。项目研究成果可为人工回灌含水层堵塞的防治提供重要科学依据。

含水层堵塞是制约人工回灌工程实施和广泛应用的重要难题，而微生物活动是导致含水层堵塞的主要成因之一。人工回灌过程中沿渗流路径可形成氧化还原分带，由此产生的氧化还原环境差异会影响含水层的微生物活动，进而影响堵塞速率和程度。同时，含水层中微生物活动及其群落演替又对氧化还原分带的形成具有潜在影响。本研究通过开展室内一维渗流试验，模拟人工回灌含水层过程，揭示了不同回灌条件下（好氧/厌氧）含水层氧化还原分带特征及含水层细菌堵塞机制。在此基础上，深入探究人工回灌含水层氧化还原分带与细菌堵塞的耦合关系。主要得到以下结论：①不同回灌条件下，含水层会形成明显的氧化还原差异，好氧回灌含水层为弱氧化带，厌氧回灌含水层由弱氧化带向还原带过渡；②人工回灌过程中，含水层细菌堵塞速率和堵塞程度与进水口的距离有关，距离进水口越近，细菌堵塞速率和堵塞程度越明显，反之越不明显。好氧回灌比厌氧回灌堵塞速率快，堵塞程度高；③好氧回灌过程中含水层呈现氧化还原分带特征，且不同分带的微生物堵塞存在极小的差异，随着氧化性减弱，含水层微生物堵塞程度降低。厌氧回灌下，含水层各分带介质渗透性呈现下降的趋势。项目研究成果可为人工回灌含水层堵塞的防治提供重要科学依据。