水位变化影响下潜流带氮素动态演化及影响机制

Nitrogen contamination posed huge risks to ecological safety and human health. The hyporheic zone is a place where river water and groundwater mutually exchange and mix. As a part of the river ecosystem, the hyporheic zone play an important role for nitrogen removal. However, influence mechanism of river water level change on dynamic change of nitrogen in the hyporheic zone is still not clear. In the present study, the hyporheic zone of Liuxi River, an important water source protection zone, will be chosen as research object. Hydrological and hydrogeological methods are used to reveal the characteristics and intensity of the hyporheic exchange occurred in the lateral interaction zone. We attempt to establish relationships between the content of nitrogen and hydrodynamic condition. Stable isotopes (δ15N-NO3- and δ18O-NO3-) and molecular biology techniques were combined to uncovering the key biogeochemical process of nitrogen. The key point of this study is to investigate the effects of river water change, physicochemical and microbial properties of sediment and groundwater on the biogeochemical process and dynamic change of nitrogen with using the multivariate statistical analysis, identifying the key controlling factors and revealing the influence mechanism on the dynamic change of nitrogen in the hyporheic zone of Liuxi River. The research results will be conducive to construct synthetic research system of the dynamic change of nitrogen in the hyporheic zone, to accurately assess ecological risks of nitrogen and to provide scientific basis for the restoration of river ecological in the Pearl River Delta areas.

氮是引起水体富营养化的关键生源要素之一，氮素的动态演化过程具有重要的生态环境意义。潜流带，作为河流生态系统的组成部分，是氮污染去除的重要区域，但水位变化影响下潜流带氮素动态演化及影响机制仍不明晰。本课题以广州市重要水源保护区-流溪河的潜流带作为研究对象，利用水文和水文地质学方法揭示潜流带水流通量动态变化特征；尝试建立氮素含量与水动力条件的关系。运用环境同位素和分子生物学技术识别氮素关键生物地球化学过程，基于多元统计分析方法探究河流水位变化、交互带内部的理化性质、微生物功能类群对氮素关键生物地球化学过程及动态演化的影响，辨析主要控制因子，揭示流溪河流域潜流带氮素动态演化及影响机制。研究结果有利于构建潜流带氮素动态演化的综合研究体系，正确评估氮污染的生态风险，为河流生态修复和水土资源的合理配置提供理论依据。

氮是引起水体富营养化的关键生源要素之一，氮素的动态演化过程具有重要的生态环境意义。潜流带，作为河流生态系统的组成部分，是氮污染去除的重要区域，但水位变化影响下潜流带氮素动态演化及影响机制仍不明晰。本课题以广州市重要水源保护区-流溪河的潜流带作为研究对象，利用水文和水文地质学方法揭示潜流带水流通量动态变化特征；尝试建立氮素含量与水动力条件的关系。运用环境同位素和分子生物学技术识别氮素关键生物地球化学过程，基于多元统计分析方法探究河流水位变化、交互带内部的理化性质、微生物功能类群对氮素关键生物地球化学过程及动态演化的影响，辨析主要控制因子，揭示流溪河流域潜流带氮素动态演化及影响机制。研究结果有利于构建潜流带氮素动态演化的综合研究体系，正确评估氮污染的生态风险，为河流生态修复和水土资源的合理配置提供理论依据。