【Introduction】
The East China Sea (ECS) has a vast continental shelf. The formation of shelf water isaffected by fluvial input from the land and the open ocean. The Kuroshio flows along its margins.
The purpose of this study is to clarify the material transport between the shelf and its surroundings.
This research is divided into two parts. (1) Qualification and quantification of the transportof the water masses from the shelf area of the East China Sea to the Kuroshio and the Sea of Japan
using various trace element composition and isotope ratios; (2) Reproduction of mass transportroute using a numerical model.
We aim to construct a synergistic research system between the model and the observation byadding more information (obtained from the results of the model) to make new observations andfeeding back the obtained results to the model again.
【Material and Method】
Samples and datasets were collected in the continental shelf edge of the East China Sea.
The salinity, temperature, DO and fluorescence data were collected by CTD. Rare Earth Element(REEs) samples were pre-concentrated and analyzed in University of Toyama. Cs samples weretreated and measured at Kanazawa University. Nutrients samples were frozen on board andmeasured by automatic analyzer at Ehime University.

Fig 1: Stations in NN464 cruise and KH-17-5 cruise (left), and the NS33 cruise (right).

【Results and Discussion】
Result I: REEs as tracer

Table 1 shows the fractions of three water masses using different sets of tracers. The simulated
fractions by four Heavy REEs (HREEs) have good agreement with the results using salinity andTable Mixing ratios of MSW, KTW and KIW using salinity and potential temperature, aswell as four heavy rare earth elements (Zhang et al., 2018).

potential temperature, suggesting HREEs are suitable and conservative water mass tracers.
Physical mixing is the dominant control on HREE distributions over remineralization. On theNS33 cruise, the REEs samples were collected. The REEs will be used as a tracer to qualify andquantify the material transport between the East China Sea and the Kuroshio using similar method.
Result II: Visualization and quantification of transport of subsurface water in Northwest Pacific
The 137Cs from the Fukushima Daiichi Nuclear Power Plant accident was used as a reliable
tracer, making it possible to visualize and quantify the mesoscale ocean mixing and material
exchange. We traced the distribution of subsurface water and quantified several diffusion
processes using 137Cs and traditional potential density anomaly. Though the depth gradually
decreases from the ocean to the continental shelf, the existence of Upper Kuroshio Intermediate
Water (UKIW) in the Tsushima strait can still be confirmed. The DIN contribution from the UKIW
to the west Tsushima Current and the entire Tsushima section was quantified, and the result
indicated that the significant DIN contribution from the UKIW cannot be ignored.

【conference presentation】
1. Siteng J. Zhu, Jing Zhang*, Shota Kambayashi, Takeshi Matsuno, Eisuke Tsutsumi,Shigenobu Takeda, Seiya Nagao , Hiroshi Inoue, Hiroshi Ogawa, Ichiro Yasuda.
From the Luzon Strait to the Tsushima Strait: Water masses and nutrient transports
approached using 137Cs.
2019JpGU meeting in Makuhari Messe, Chiba, Japan, May 2019.
2. Siteng J. Zhu, Jing Zhang*, Shota Kambayashi, Takeshi Matsuno, Eisuke Tsutsumi,Shigenobu Takeda, Seiya Nagao, Mutsuo Inoue, Katsumi Takayama, Hiroshi Ogawa, IchiroYasuda.
Transport of the upper Kuroshio Intermediate Water from Northwest Pacific to the Sea ofJapan: using 137Cs as a tracer.
2019 JOS meeting, Toyama, Japan, August 2019.
3. 野口忠輝, 張勁*, Wenkai Guan, Bingzhang Chen, Meixun Zhao, Yuanli Zhu, 石坂丞二,松野健, 安田一郎.
Influence of Atmospheric Nutrient Deposition and Phytoplankton Species Composition in theWestern North Pacific Subtropical Area in Winter.
SOLAS Open Science Conference 2019, Sappro, Japan, March 2019
4. 野口忠輝, 張勁*, Wenkai Guan, Bingzhang Chen, Meixun Zhao, Yuanli Zhu, 石坂丞二,松野健, 安田一郎.
Atmospheric Nitrogen Deposition on the Sub-Tropic NWPO and Its Impact.
2019 年度日本海洋学会秋季大会、富山、2019 年 9 月.
5. 野口忠輝, 張勁, Wenkai Guan, Bingzhang Chen, Meixun Zhao, Yuanli Zhu, 石坂丞二, 松野健, 安田一郎.
大気由来微量元素の供給と海洋表層基礎生産に対する影響評価.
2019 年度 日本地球化学会、東京、2019 年 9 月.