| The Yangtze River diluted water (YRDW) and the intruded Kuroshio Subsurface Water (KU) are two main sources of nutrients in yellow sea and the east china sea. In recent years, there have been many investigations and researches about nutrients behavior of YRDW and have got some achievements. For KU, researchers are mostly focused on Taiwan Warm Current (TWC), especially its seasonal variation, structure and composition, and the nutrient flux. But the results caused by KU are not only TWC, but also the upwelling and eddy at the edge of Kuroshio Current near the continental shelf. In this text, based on the cruises carried out in summer 2006 and spring 2009, the bioactive elements condition of the Yellow Sea and the East China Sea was studied, the influence area of coastal water and Kuroshio Water in different seasons was divided, and the nutrient characteristic for each kind of water was studied. As one of the most important consequences of intruded Kuroshio Subsurface Water, the Cold Eddy northeast of Taiwan was mainly studied, and its structure, nutrient condition, and nutrient flux to the East China Sea were also discussed preliminarily. Conclusions were summarized as follows:(1) The analysis of nutrients concentration shows that:the nutrient concentration is higher in upper layer than that in the lower layer both in spring and summer. The stratification depth in two seasons is different that which is below 30m in spring and above 30m in summer. In spring, the average concentration of DIN and SiO3-Si in whole water are respectively (6.88±8.30)μmol/L and (9.96±14.25)μmol/L, which are (5.50±5.38)μmol/L and (8.30±9.89)μmol/L in summer, the concentration of PO4-P is about 0.30μmol/L in both spring and summer. But it shows variously in different layer because of the change of stratification depth. DO decreases from the surface to the bottom. In the upper layer, DO is higher in spring than in summer because it is main effected by temperature and phytoplankton. But in the lower layer (below 30m), it is at the same lavel in spring and summer, since its effective factor becomes the decomposition of organic matters.(2) YRDW extends to 125.5°E in summer, while only 124°E in spring. The distribution of DIN and SiO3-Si at surface and 10m are mainly influenced by YRDW, it reduces from Yangtze estuary to the middle of the Yellow Sea and the south of the East China Sea. The concentration of PO4-P is declined sharply to 0.1μmol/L out of the Yangtze estuary because YRDW offers little PO4-P. Below 30m, nutrients are basically controlled by decomposition of particulate matter and intruding of Kuroshio Subsurface Water (including TWC). TWC may horizontally extend to Yangtze estuary (123°E,32°N), and vertically up to 10m, while it has already been metamorphosized. Coastal water contribute plentiful nutrients expect PO4-P, while the upwelling in the coastal area and intruding of Kuroshio Subsurface Water (including TWC) may significantly influence the distribution of PO4-P.(3) The East China Sea is divided into three parts which are coastal influence area, mixed area and Kuroshio influence area. The extending area of coastal water (especially YRDW) and Kuroshio water is changed with seasons and layers. YRDW can only extend to 10m vertically in spring and summer, and horizontally extends to 125.5°E in summer, while only 124°E in spring. In spring, Kuroshio occupies the most area of the East China Sea with little diversity in each layer. While in summer, it is changed with depth, YRDW mainly control the upper layer and Kuroshio water effect the bottom.(4) The cold eddy found in the northeast of Taiwan in spring 2009 is named "PengHuaMian" cold eddy. It lies in the northeast-southwest direction with two cold centers and extends to nearly 100m. The intensity of the north upwelling is stronger than the south. The upwelling area are surround by the mixing water of Taiwan Strait water and the continental water at east and the Kuroshio surface water above and at west. The average concentration of DIN, PO4-P and SiO3-Si are respectively 4.3 times,2.6 times and 2.0 times of the mixing water, and 3 times,2.4 times and 2.4 times of the Kuroshio Surface Water. The N/P of the upwelling water is 14.76 while the Si/N is 1.44, so it may be helpful to the limitation of PO4-P in the East China Sea. In the upwelling area, the DIN flux in spring is slightly lower the year flux of YRDW in 1980s, and is about 27% of that in 1990s. While the flux of SiO3-Si in the upwelling area in spring is 2 times of the year flux of YRDW, while it is 3-5 times for PO4-P. Compared with the typical upwelling in the East China Sea, the upwelling studied in this text has the same intensity with fishing ground of Zhoushan and Yushan.
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