Abstract: Seawater samples in the Changjiang Estuary and the adjacent East China Sea (ECS) were collected at 106 and 104 stations, respectively, in February and July 2014 during which concentrations of nutrients (including NO₃-N, SiO₃-Si, PO₄-P, NH₄-N, and NO₂-N) were measured.The distribution and variation of nutrients showed distinct seasonal variation pattern.In summer, the coverage area of seawater with high concentrations of NO₃-N, SiO₃-Si, and PO₄-P was obviously larger than that in winter, owing to the increased Changjiang discharge and the seawater stratification.On the contrary, however, the concentrations of the three nutrients in the offshore seawater were generally lower at surface in summer than those in winter.NH₄-N and NO₂-N showed positive correlations with salinity in summer while negative relationships in winter, and this seasonal reverse pattern was largely ascribed to their sharply increased concentrations in the Changjiang freshwater end-member from summer to winter.The Changjiang runoff was transported to the pelagic oceans in separated patches, rather than in continuous plume.Comparison of nutrient concentrations among different patches validated that the Changjiang Estuary and the adjacent areas were a tremendous sink for most nutrients in summer.The non-conservative processes of nutrients occurred not only in the estuarine and shelf areas where freshwater and seawater mixed, but also in the Changjiang freshwater areas within the river mouth.