Abstract
Temporal variations of dissolved nitrogen and phosphorus were measured in Hiuchi-Nada and Iyo-Nada in the late spring . In Iyo-Nada, water temperature and salinity stratified, which caused vertical distributions of dissolved inorganic nitrogen and phosphorus (DIN and DIP). Dissolved organic nitrogen and phosphorus (DON and DOP) were superior to DIN and DIP, respectively. Temporal variations of DIN, DIP, DON and DOP were small in Iyo-Nada. In Hiuchi-Nada, the amounts of DIN and DIP were even smaller than those of DON and DOP similar to Iyo-Nada. However, DON and DOP changed dynamically daily in contrast to those in Iyo-Nada . This difference between the two seas could be related to a tidal current which caused the resuspension of deposits on the sea floor in the case of Hiuchi-Nada . These results show that the regional differences are reflected in the temporal variations of DON and DOP and to a limited extent in the temporal variations of DIN and DIP. This suggests the importance of measurements of DON and DOP in view of the nitrogen and phosphorus budgets.
