溶解性有机氮（DON）是水体中活性氮的重要来源，氨基酸和多肽是DON的主要组成成分。以往有关氨基酸和多肽转化研究多集中在生物体系和模拟水体中的实验室研究，因此，其生物转化和化学转化之间相互影响及转化过程中碳、氮元素形态转化等问题仍未阐明。本课题拟系统开展典型氨基酸和多肽在湖泊中生物化学转化动力学和产物分析以及碳氮元素的形态分析等工作，探究其半衰期与结构间的相互关系；量化非生物转化反应对其生物可利用性的影响程度；揭示水体微生物群落对转化过程的响应特点；进一步厘清氨基酸和多肽转化过程中水体氮元素和碳元素的形态变化及之间的耦合关系。本课题的完成，有助于理解水生生态系统中有机氮物质的转化机制及环境效应，同时有助于理解淡水生态系统中生物作用和化学作用在水体净化中的作用和主要影响因素。

Dissolved organic nitrogen (DON) accounts for large portion of reactive nitrogen, and dissolved free amino acid and peptides are major compositions of DON in aquatic system. Previous studies focused on the transformation of amino acids and peptides in either biological system or simulated water, and therefore the mutual influence between biological and chemical transformations in natural water and the coupling relationship between nitrogen and carbon during the transformation process has yet been revealed. In this project, we want to systematically investigate the transformation in natural water. Based on the determined reaction constants and structure identified intermediates, it could reveal the relationship between half-life and chemical structure of amino acids and related compounds, and quantify the influence of abiotic transformation on the change of bioavailability. Meanwhile, the study is to reveal the response pattern of aquatic microbes and the coupling relationship between nitrogen and carbon during the transformation of amino acids and related compounds. The findings of this project is helpful in understanding the environmental fate and potential effects on fresh aquatic ecosystem, and also helps in understanding the contribution of biotic and abiotic reactions in water body purification and the corresponding influence factors.