城市尾水排放对受纳水体溶解有机质组成及其生物有效性影响机制

Wastewater treatment plant (WWTP) effluent, as water supplement for surface water, is usually to be discharged into adjacent water bodies, such as rivers, lakes and reservoirs. However, there are large gaps about the current comprehensive mechanisms for the impacts of WWTP’s effluent on streamwater quality and phytoplankton community succession in receiving water bodies. In view of this situation, we assumed that migration and transformation of dissolved effluent organic matter (dEfOM) were dicated by suspended particles, photobleaching and microbial in receiving water bodies. Therefore, these environmental behaviors affected streamwater dissolved organic matter (DOM) compositions associated with its bioavailability. On the basis of hydrophilic/hydrophobic and fluorescent properties, we will use the high-resolution mass spectrometers to characterize dEfOM and streamwater DOM compositions at molecular level. This present research will focus on the dynamics of absorption/ desorption, photo-degradation and microbial degradation for different dEfOM fractions in receiving water bodies, to probe the effects of dEfOM’s environmental behaviors on streamwater DOM compositions. Simultaneously, we will investigate the bioavailability of the altered streamwater DOM compositions to analyze the ecological response to WWTP’s effluents. As these aims will be succeed, the molecular mechanisms for the impacts of effluents on water quality and ecological effects would be easily to be understood, and the theories concerning replenish water for effluents would be further developed. These results also provide scientific data for related environmental managers.

城市污水处理厂尾水作为河湖补给水源是尾水资源化利用的重要体现。针对目前尾水溶解有机质dEfOM不同化学组分对受纳水体生态环境效应影响机制尚不明确，本项目设想“dEfOM进入受纳水体后其运移转化行为会受到悬浮颗粒物吸附/解析及光化学和微生物降解的影响，进而导致受纳水体中溶解有机质化学组成及其生物有效性发生改变”。因此，本项目在亲疏水性和光谱学特征分析的基础上，采用高分辨质谱技术进一步从分子水平解析dEfOM的化学组成特征。通过实验室模拟和野外验证实验相结合，研究不同化学组分dEfOM在受纳水体中运移转化规律，分析其运移转化历程对受纳水体中溶解有机质化学组成的影响；探究受尾水排放影响的溶解有机质生物有效性，剖析尾水排放对受纳水体中藻类群落演替的影响。据此阐明尾水排放对受纳水体生态环境效应的影响机制，深化城市尾水资源化利用理论研究，为受尾水排放影响的受纳水体水质改善和科学管理提供可靠的理论依据。

污水处理厂尾水有机质（Effluent organic matter, EfOM）进入受纳水体后，将受到一系列生物化学作用的影响，进而影响受纳水体中溶解有机质（Dissolved organic matter, DOM）的组成特征及其生态效应。在国家自然基金委的支持下，本项目主要基于LC-MS平台建立了表征分子水平DOM 解析方法，拓展了三维荧光区域积分法（EEM-FRI）在流域环境中的应用；在此基础上，探明了污水处理厂尾水溶解有机质对受纳水体（河流和湖泊）的影响，揭示了EfOM在受纳水体中的变化规律；阐述了受纳水体（湖泊）沉积物微生物对溶解有机质的影响机制。在本项目的资助下，在Chemosphere, Science of the total environment 等杂志发表6篇论文（其中SCI收录3篇），申请且已授权专利1项，在国内外学术会议上做口头报告3次，合作撰写专著1部。研究结果可为污水处理厂尾水资源化利用和流域水环境管理等提供理论指导。具体结果如下：.（1）LC-Q-TOF-MS高清质谱，能够准确、快速地揭示DOM复杂化合物的分子水平组成特征。利用LC-Q-TOF-MS与EEM技术联用确定了河流、湖泊水体中DOM主要来自与人类活动和系统内源生产。.（2）EfOM进入受纳水体后，光化学降解和微生物降解是EfOM转化的主要驱动力，且光化学降解能促进有机质的微生物生产。研究发现，当EfOM进入受纳水体后，其含量及组成特征均会发生较大的变化，66%的EfOM将被光化学和微生物降解，只有33%的EfOM难以降解而稳定存在于受纳水体中。.（3）本项目提出了湖泊土著微生物的影响下溶解有机质的定向转化途径，且其DOM的组成结构也将受到土著微生物的影响。这将表明湖泊在流域生态系统中对DOM的环境行为和生态效应起到了重要的调节作用。.