Characteristics Of Nutrient In The Southern Yellow Sea And Northern East China Sea From2011to2013

This study force on characteristics and mechanisms of nutrient and circulatingcurrent in the southern Yellow Sea and northern East China Sea, based on the dataobtained from seven voyage, including spring, summer, autumn surveys from2011to2013supported by National Basic Research Development Program (973program)"Interaction between Marine Environmental Change and Jellyfish outbreaks ".The main conclusions are presented as follows:1. The overall concentration of nutrient in the southern Yellow Sea and northernEast China Sea is high in coastal zones and decreases offshore. In general, distributionof nutrient shows obvious seasonal variations. In spring, there is small differencebetween the concentration of nutrient at surface and bottom. In summer, the contentof nutrient is lower in surface and higher at the bottom of central southern Yellow Sea.High value of PO43--P and SiO32--Si appears in the deep water offshore Zhejiang andFujian.In autumn, the areas of high content of nutrient still exist, with differentdistribution and highest value patterns. NO3--N is the major component of DIN in allthree seasons, followed by NH4+-N, and NO2--N as the lowest. The highestconcentration of NO3--N appears in summer, which is significantly higher than inspring and autumn. According to the season of summer, autumn and spring, the levelsof NH4+-N are arranged in descending order.2. The distribution of different nutrient is influenced by current, respectively. Thecontent of nutrient is affected by Changjiang Diluted Water and Yellow Sea ColdWater Mass, significantly. In addition, Subei Coastal Current plays important role inthe distribution of DIN, while Taiwan Warm Current has a strong impact on PO43--P.In coastal zones, the major factors influencing the distribution of nutrient areChangjiang Diluted Water, Taiwan Warm Current and Subei Coastal Current, whilethe Yellow Sea Cold Water Mass is an important current in southern Yellow Sea.3. The vertical profiles of nutrient along transect PN show obvious seasonalvariation. In spring, the concentrations of nutrient are higher along this transect. Insummer and autumn, lower values of nutrient appear in the surface water. With thedepth increasing, the content of nutrient ascends gradually, and the nutricline occursin the section. The location and intensity of nutricline is closely related to ChangjiangDiluted Water and Taiwan Warm Current.4. The vertical profile of nutrient along transect E also show obvious seasonalvariation. Generally, the content of nutrient in the section is lower in surface andhigher at the bottom. In spring, higher level of nutrient appears at two bottom regionsof the section. In summer and autumn, the water at the bottom reveals significantlyhigher value of nutrient, with the maximum value occurs in summer. The distribution of nutrient shows the same pattern with local current, including Yellow Sea ColdWater Mass.5. Water stratification and vertical mixing of seawater have impact on thedistribution of nutrient. The distribution and seasonal variation of nutrient are in wellcorrespondence with intensity and location of water stratification.