| Availability of labile nitrogen (N) is important in shaping composition, diversity, and dynamics of organisms and may impact ecosystem functioning in aquatic environments. Our knowledge on biogeochemical cycles of N and microorganisms that mediate these processes has been significantly improved in the past few decades. New findings, such as the discovery of anaerobic ammonium oxidation (anammox), an alternative route to remove bioavailable N, have shifted the traditional paradigm of nitrogen cycling. A new question, therefore, is raised on the contribution of anammox, relative to denitrification, in N2 production. Moreover, some long-standing questions, such as the chemical composition of labile dissolved organic nitrogen (DON) pool and the transformation mechanism of labile DON are yet to be solved. The overall objective of this research was to improve our understanding of bacterially mediated N transformations in aquatic environments, specifically on nitrogen removal by anammox and denitrification and on polyamine (a labile DON) transformation. |
