[A-OS13] Exploring Variability and Changes in Ocean Biogeochemical Cycles

[AOS13-P04] The roles of Kuroshio-origin new and regenerated nutrients over the East China Sea shelf based on a physical-biological model

*Jing Zhang¹, Xinyu Guo², Liang Zhao¹ (1.Tianjin University of Science and Technology, 2.Ehime University)

Keywords:Kuroshio, new nutrient, regenerated nutrient, new production

The Kuroshio brings a large amount of nutrients into the East China Sea, making it the largest source of external nutrients. However, significant unknowns remain regarding how they support primary production and how these Kuroshio-intruded nutrients are regenerated in the East China Sea. A physical-biological coupled module and a nutrient tracking module were used to classify Kuroshio nutrients (including dissolved inorganic phosphorus (DIP) and dissolved inorganic nitrogen (DIN)) into two types: new nutrients and regenerated nutrients. The spatiotemporal distributions of new and regenerated nutrients in the East China Sea shelf were discussed, and the contributions of Kuroshio nutrients to the new and regenerated production on the East China Sea shelf were assessed. New production supported by new nutrient is mainly located in the outer shelf, while the regenerated production supported by regenerated nutrient can extend into the inner shelf. The new DIN inventory from the Kuroshio makes up over 70% of the total over the East China Sea. It supported new production that accounts for 40% of primary production. Conversely, the regenerated production supported by regenerated DIN makes up over half of the primary production, but the inventory of regenerated DIN makes up less than 30% of the total DIN from the Kuroshio. The new production and export production supported by Kuroshio nutrients are not balanced in the ECS shelf. The difference between them is attributed to the offshore transport of the regenerated nutrients, indicating a new reason for the mismatch of new and export production of the shelf seas.