Chemicohydrographic Characteristics Along the Vertical Section in the Yellow Sea

Based on the in-situ data obtained during the survey carried out in the Yellow Sea from July 2006 to November 2007,the chemicohydrographic characteristics along the vertical section of the whole cold water mass in the Yellow Sea are studied.The results show that the distributions of hydrological and chemical elements along the vertical section are mainly influenced by seasonal changes of the Yellow Sea Warm Current(YSWC)and the Yellow Sea Cold Water Mass(YSCWM).In winter,due to the influence of YSWC,the vertical distributions of all elements in the North Yellow Sea are homogeneous,while the biogenic element in the deep of the South Yellow Sea shows a gradient distribution.In spring,a stratification phenomenon occurs in the North Yellow Sea,with the values of DO and pH being higher in the upper water than in the lower water and the nutrients being in an opposite way,while in the South Yellow Sea the stratification is not significant.In summer,strong thermocline and halocline occur along the vertical section,above which the nutrients in the water are exhausted by phytoplankton and below which the nutrient concentration in the water increases with the water depth.The DO is,however,goes in an opposite way.The maximal values of both DO and pH occur in the 30mlayer in the South Yellow Sea,whereas in the North Yellow Sea no such a phenomenon occurs.In autumn,the spring layer goes down.As a result,the maximum of the nutrients occurs in the cold waters of the Yellow Sea due to their continuous accumulation and the DO value reaches its minimum.In addition,both the formation and the disappearance of the cold water mass happen earlier in the North Yellow Sea than in the South Yellow Sea.