结合态氨基酸氯化生成卤代N-DBPs的机制与调控研究

Amino acids (AAs) are the important precursors of highly toxic halogenated nitrogenous disinfection by-products (N-DBPs) in drinking water. The present studies on N-DBPs formation from nitrogenous model precursors mainly focused on free AAs. However, AAs in combined forms (e.g. oligopeptides and proteins) are more abundant than free AAs in natural waters. Notably, the different configuration of AA residues in the three dimensional structure of combined AAs play a key role in the formation of halogenated N-DBPs. In order to control the formation of halogenated N-DBPs in drinking water, it is urgently needed to screen the key AA residues which may form halogenated N-DBP in combined AA, and reveal their contribution in the formation mechanism of chloro-, bromo-, and iodo- N-DBPs during chlorination. In this proposal, we plan to establish the comprehensive analytical methods for concentration and formation potential of halogenated N-DBPs, which could be used to monitor N-DBPs and their formation potentials in raw water and treated water. We attempt to develop the mass-spectrometric technique based on the precursor ion scanning and collision induced dissociation, which could be used to discriminate the key AA residue in combined AAs. And, the nitrogen source analysis technology of halogenated N-DBPs will be developed by calculating the accessibility of AA residues and tracing nitrogen isotope in combined AAs, which could help to reveal the formation characteristics and pathway of halogenated N-DBPs in the three dimensional structure of combined AAs. At last, the source and process control mechanism of the halogenated N-DBPs will be clarified, and the relevant control solution will be presented. These studies in the proposal may provide theoretical basis and technical support for the control of typical chloro- N-DBPs and emerging bromo- and iodo- N-DBPs in drinking water.

氨基酸是饮用水中高毒性卤代含氮消毒副产物(N-DBPs)的重要前体物。现有研究主要关注游离态氨基酸的氯化反应机制，然而天然水中多为结合态氨基酸，其所包含的氨基酸残基在三维空间排布的不同将影响卤代N-DBPs的生成特性。因此，甄别关键氨基酸残基，并揭示其生成氯、溴、碘代N-DBPs的机制是实现卤代N-DBPs综合控制的关键。本项目拟建立卤代N-DBPs的同时定量分析与生成潜能测定的方法体系并开展监测；开发基于前体离子扫描和碰撞诱导解离的质谱分析技术，甄别结合态氨基酸中的关键氨基酸残基；研发基于氨基酸残基可及性计算与氮同位素示踪的卤代N-DBPs氮源解析技术，揭示出三维构象下关键氨基酸残基氯化生成卤代N-DBPs的多因素影响规律和路径；阐明卤代N-DBPs的源头与过程调控机理，提出相应控制方案。以上研究将为饮用水中典型氯代N-DBPs和新兴溴碘代N-DBPs的综合控制提供理论依据和技术支撑。

饮用水中卤代含氮消毒副产物（N-DBPs）因毒性大分布广而备受关注。广泛分布于水源水体中的结合态氨基酸等有机物是N-DBPs的重要前体物。明确结合态氨基酸中生成N-DBPs的关键氨基酸残基、揭示典型前体物氯化生成N-DBPs的机制是实现水中高毒性N-DBPs污染物有效控制的关键。本项目抓住这一关键环节，从分析方法开发、关键前体物解析、生成机制和控制技术等方面开展了递进式系统研究。主要取得以下成绩：.一、分析方法开发：①开发出系列微痕量消毒副产物精确分析技术，得到较好的推广应用。②探明了N-DBPs水解动力学规律，发展出溴代、碘代N-DBPs的生成潜能评价新方法。③揭示出美国环保局卤乙酸经典检测方法(EPA552.2)在用于实际饮用水检测时准确度不高的本质原因，提出了相应解决方案。.二、关键前体物解析：①甄别出有机高分子混凝剂为N-DBPs的重要前体物。②发现大气颗粒物对N-DBPs的产生具有不可忽视的贡献，阐述了其通过干湿沉降汇入水源水对N-DBPs生成的重要影响。③开拓了消毒副产物前体物从源头到龙头的全过程来源，阐明了其多介质转化新机制。.三、生成机制研究：①揭示出游离态和结合态氨基酸消毒生成新型消毒副产物的重要机制，发现结合态氨基酸中的肽键决定了N-DBPs的生成特性；②阐明了混凝过程中“消毒副产物”产生机理，率先提出“混凝副产物”的概念；③发现还原性含硫基团与消毒剂之间具有较高的反应活性。④探明管网中多种含氧阴离子对溴代DBPs浓度波动的影响机制。.四、控制技术研发：①针对结合态氨基酸生成N-DBPs的关键环节，开发出基于硫酸根和羟基自由基的N-DBPs前体物削减技术。②针对氨基酸含量较高的水源，开发出生物降解目标性前体物抑制N- DBPs产生的源头控制技术。③针对富营养化高有机氮水源水质特征，从源头控制角度，开发出预处理-强化常规-深度处理全流程N-DBP前体物削减技术。④从消毒过程控制角度，开发出二氧化氯与氯胺优化组合消毒抑制N-DBPs产生的过程控制技术。.总之，项目负责人以第一/通讯作者在ES&T和Water Research等环境、水处理领域重要期刊上发表SCI收录论文30篇，同时受邀撰写消毒副产物邀请论文2篇。申请国家专利10项，国际专利1项，授权发明专利2项。相关技术在上海和长三角地区水司分析中心和水厂得到业务化应用。