Taking the Yangtze Estuary as a typical study area, this project aims to (1) study the spatial and temporal distributions of ANAMMOX in the estuarine and coastal environments usinga stable isotopes and molecular biological techniques; (2) analyze the compositions, diversities, and abundances of ANAMMOX bacterias ; (3) quantify the relationship between the reaction rates of ANAMMOX and the community dynamics of ANAMMOX bacteria; (4) explore the key environmental facotrs and mechanism controlling ANAMMOX, and (5) discuss the contribution of ANAMMOX to nitrogen cycling in estuarine and coastal environments. The results may provide scientific support for the protection and management of estuarine and coastal environment as well as nitrogen pollution control at the catchment scale.