岸滤系统中溶解性有机质与微量污染物共代谢的分子机制

Recently, the occurrence of micropollutants in source water has caused wide concern over drinking water safety in China. Micropollutants contain an extremely large number of compounds with different origins, and the number of micropollutants identified in source water is continuously increasing. Riverbank filtration (RBF) as known as high efficiency and inexpensive natural process in removing micropollutants, has attracted worldwide attention. Micropollutants in water can be degraded by microorganism in a process called natural attenuation. The presence of dissolved organic matter (DOM) has been shown to be a key factor in this natural attenuation process, indicating that DOM addition could be used to enhance biodegradation of the micropollutants. As DOM is an amalgam of heterogeneous compounds consisting of gradients of microbial and physicochemical reactivity, the co-metabolism of DOM and micropollutants at the molecular level are not well understood. In our project, RBF was selected as the pointcut to study the co-metabolism of DOM and micropollutants. Firstly, we will utilize the Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) to unambiguously identify the change of DOM molecular composition. Then, high throughput sequencing and high throughput fluorescence quantitative PCR were used to reveal the microbial community composition and metabolic process during degradation, as to reveal the co-metabolism of DOM and micropollutants in the RBF system. The results of this project will not only have scientific significance in fundamental understanding the role of DOM in micropollutants biodegradation, but also provide important theoretical support to develop a robust biodegradation technology using DOM amendment to remove micropollutants.

近年来我国很多饮用水水源存在不同程度的微污染现象，微量污染物种类繁多，检出数量也在逐年增多。岸滤在饮用水处理过程中效率高、成本低。在岸滤系统中，水体中污染物通过物理化学以及微生物作用等自然衰减过程可以得到较好的去除。溶解性有机质（DOM）的存在是微量污染物自然衰减过程的关键因素，这表明DOM的添加能够增强微量污染物的降解。但鉴于DOM的高度复杂和极端异质性，以往的研究始终不能从分子水平上深入解析DOM与微量污染物的共代谢机制。本项目选择岸滤系统作为切入点，首先采用超高分辨率质谱对DOM分子组成的变化进行表征，其次采用高通量测序和高通量荧光定量PCR对降解过程中微生物群落组成及代谢过程进行分析，进而揭示岸滤系统中DOM与微量污染物共代谢的分子机制。本项目研究结果不仅对了解DOM对微量污染物的去除机制具有科学意义，而且为如何高效低药地去除微量污染物等环境问题提供十分重要的理论依据。

近年来我国很多饮用水水源存在不同程度的微污染现象，微量污染物种类繁多，检出数量也在逐年增多。岸滤在饮用水处理过程中效率高、成本低。在岸滤系统中，水体中污染物通过物理化学以及微生物作用等自然衰减过程可以得到较好的去除。溶解性有机质（DOM）的存在是微量污染物自然衰减过程的关键因素，这表明DOM的添加能够增强微量污染物的降解。但鉴于DOM的高度复杂和极端异质性，以往的研究始终不能从分子水平上深入解析DOM与微量污染物的共代谢机制。本项目主要开展了如下研究工作：选择江西抚河岸滤系统作为切入点，采用超高分辨率质谱对河岸土壤介质、地表水及取井水的DOM分子组成的变化进行表征，其次采用高通量测序对降解过程中微生物群落组成及代谢过程进行分析，并对地表水及取井水中的典型有机微量污染物进行了定量及定性分析。研究主要发现：（1）磺胺甲恶唑和卡马西平在抚河岸滤系统上、中、下游6个断面地表水中广泛存在，取水井中的含量均低于检测线。（2）识别了岸滤系统土壤中的微生物群落组成以及微生物多样性和丰富度的变化特征。在门水平上，此岸滤系统中的土壤微生物群落以变形菌门（Proteobacteria）、绿弯菌门（Chloroflexi）、酸杆菌门（Acidobacteria）、放线菌门（Actinobacteria）为主。由土壤微生物多样性、丰富度指数分析发现，土壤微生物群落多样性和丰富度总体特征为：中游>上游>下游，这与微生物稀释性曲线分析所得结果一致。（3）在属水平上对土壤微生物进行分析，发现了链霉菌属（Streptomyces spp.）、红球菌属（Rhodococcus spp.）、硝化螺菌属（Nitrospira spp.）等7种核心微生物菌属（相对丰度>1%）。其中罗尔斯顿菌属、芽胞杆菌属为两种典型的磺胺甲恶唑降解菌属，链霉菌属和红球菌属为两种典型的卡马西平降解菌属。本项目研究揭示了岸滤系统中DOM与微量污染物共代谢的分子机制。本项目研究结果不仅对了解DOM对微量污染物的去除机制具有科学意义，而且为如何高效低药地去除微量污染物等环境问题提供十分重要的理论依据。