城市黑臭河道水沉积物微界面氧环境特征与调控机制研究

Urban rivers in China have been confronted with the trouble of Black-odorous water body and heavily polluted sediment by overloaded nutrients and contaminants in recent years. Oxygen circumstances in the sediment-water interface regulated by both processes of oxygen depletion and reoxygenation is the key to understand the degradation and restoration of urban river ecosystems. This project aims at characterizing the dynamics of oxygen circumstances in corresponding to the physiochemical property of water and sediment, under the impact of oxygen-depleting and reductive materials as well as biogenic and abiogenic disturbance to the sediment-water micro-interface, to provide the basis for better management of the black-odorous rivers..From the methodological point of view, this project focuses on the undergoing processes in and out of the sediment-water microinterface, uses micro-optode and electronic microsensor techniques which are characterized by high resolution to verify the crucial principles and mechanisms regulating interfacial oxygen circumstances. Comprehensive microcosmic and macroscopic analysis, and in situ and laboratory simulation experiments will be performed to study the microorganisms and their roles in the transport and transformation of major black-odorous compounds and the coupling relationship among the adsorption/desorption of these compounds, nitrification, denitrification, ammonia volatilization and oxygen depletion, reoxygenation processes..Sediment-water microinterface is the specific scale and field chosen to establish the research system combing formation and transport of black-odorous compounds, microorganism transformation of nitrogen and phosphorus, reoxygenation and dynamics of oxygen equilibrium on characteristics of oxygen circumstances in urban black-odorous rivers. Results will help to the analysis of mechanisms regulating oxygen based on the comprehensive interpretation of behavior of black-odorous compounds, biogenic elements and reoxygenation dynamics. This project will also make it feasible to set up the experimental system for continuous monitoring at high resolution of micro-interface oxygen, hydrogen sulfide, physico-chemical parameters relevant to black-odorous phenomenon, thus to provide the scientific support to the remediation of urban black-odorous rivers.

针对城市河道水质黑臭、沉积物污染严重这一典型环境问题，通过原位实验和室内模拟，探讨沉积物基本理化性质、污染河道沉积物-水界面耗氧物质和还原态物质对界面氧环境特征的影响，阐述生物与非生物扰动对沉积物-水界面氧分布的影响。以水-沉积物界面过程为核心，运用高分辨率微电极技术测定界面氧环境特征相关要素作用规律与机理，研究微生物对沉积物-水界面氮迁移与转化的影响，探讨表层沉积物氮吸附释放过程、沉积物-水界面反硝化和氨挥发等主要脱氮过程的响应。围绕水-沉积物界面场域核心，构建黑臭物质形成与迁移、氮磷生源要素微生物转化、复氧过程及平衡动态综合调控的黑臭河道底质氧环境特征研究体系。从系统平衡角度综合分析黑臭物质、氮磷要素与复氧动态三大因素对界面氧环境特征的调控作用机制。建立基于微光极、微电极技术的水-沉积物界面高分辨率溶解氧、硫化氢及黑臭相关理化因子连续测定技术，为城市黑臭河道治理提供科学支撑。

背景：黑臭河道水-沉积物微界面是城市水体中黑臭物质形成与扩散、氮素迁移与转换的重要调控场域，其组成与氧环境特征、界面过程与功能微生物响应机制尚待探讨。.主要研究内容：（1）微界面溶氧原位测定技术及微生物定量分层取样技术。基于溶氧微光极技术开发可一次完成泥水界面不同高度、不同水平位置的溶氧检测技术及装备；开发水生植物根不同部位根际微生物的原位取样技术；（2）水沉积物微界面氧环境特征与黑臭过程耦合机理。分析污染河道沉积物碳氮赋存特征，研究有机质对氮的吸附解吸影响；通过微量定量采样技术检测污染河道水-沉积物微界面结构、组成及主要理化性质、氧环境特征、黑臭物质赋存形态与分布规律及主要理化性质与溶解氧对其的影响；（3）复氧过程中水沉积物微界面氧环境响应动态过程。研究曝气扰动对水-沉积物界面基本理化性质、物质组成、黑臭物质及氮素迁移转化的影响；对典型景观植物根围DO原位时空变化进行表征，揭示生物复氧过程对水-沉积物界面氧环境特征的影响；（4）水沉积物微界面氧环境与微生物时空变化耦合过程。分析黑臭水体沉积相和水相中氮素循环细菌的时空分布；分析沉积相、水相、水沉积物界面及典型湿地植物根系微生物群落结构、功能菌群丰度；（5）环境因子对植物生长生理特性的影响。研究洪水发生时淹水、光照、水分等主要环境因子交互作用对耐淹植物生长发育的影响；研究不同水深对典型沉水植物生理生化活性的影响，探讨植物群落最适生长水位。.主要结果及意义：微界面溶氧原位测定技术及微生物定量分层取样技术的研究，为后续界面微量定量采样与测定提供保障。黑臭水体氧环境受碳有机物生化耗氧和硝化耗氧共同作用，氮素是影响有机质分解的重要因素。曝气复氧会影响水-沉积物界面基本理化性质、物质组成、黑臭物质及氮素迁移转化过程，是黑臭水体氮素循环细菌时空分布及植物根际微生物变化的重要因子。淹水持续时间和水深梯度是影响植物生长发育、生理特性的重要环境因子。