东海PN断面夏季温盐及化学要素的分布特征

DISTRIBUTION FEATURES OF T-S AND CHEMICAL CONSTITUENTS AT THE PN SECTION IN THE EAST CHINA SEA DURING SUMMER

由东海PN断面夏季温盐度及化学要素CTD资料分析表明 ,东海夏季的温跃层和盐跃层在次表层生成 ,其强度随着跃层自陆架坡折区至近岸和外海的上移逐渐减弱。陆架区近表层的温度和盐度呈垂直均匀分布 ,冲绳海槽次表层呈高温、高盐 ,近表层呈高温、低盐 ,底层呈低温、次高盐特征。溶解氧浓度自近岸到外海由低变高 ,表层至底层溶解氧浓度在陆架区由高变低 ,冲绳海槽区则先由低变高然后又由高变低。总二氧化碳浓度自表层至底层和自陆架坡折区到近岸和外海由低变高。磷酸盐和硅酸盐浓度自近岸至外海由高变低 ,而自表层至底层由低变高。陆架区的近表层和陆架坡折区分别有一个高碱度区。温盐及化学要素的分布特征与夏季海区垂直环流的反气旋运动、长江冲淡水及黑潮水入侵和海面强热辐射有关。此外 ,化学要素分布还与夏季海区的温盐结构。

Based on the CTD data of the hydrology and chemical constituents at the PN section located in the East China Sea in August 1994, analysis for vertical distributions of the temperature, salinity, oxygen, total carbon dioxide, phosphate, silica and total alkalinity was carried out. The results show that the thermocline and halocline form in the subsurface during the summer, and their intensities become gradually weaker with their up shift from the shelf break area to the near shore and the outside sea. The oxygen concentration increases from the near shore to the outside sea, and decreases from the surface layer to the bottom layer over the shelf area, and increases then decreases from the surface layer to the bottom layer at the Okinawa Trough. The total carbon dioxide concentration increases from the surface layer to the bottom layer, and from the shelf break area to the near shore and to the outside sea. The concentrations of phosphate and silica decrease from the near shore to the outside sea, while increase from the surface layer to the bottom layer. The concentration of total alkalinity was high in the near surface layer of the shelf area and the shelf break area. The vertical distributions of the temperature, salinity and chemical constituents are attributed to the anticyclonic flow of the vertical circulation during the summer, to the flows through of Changjiang River diluted and Kuroshio water, and to high heat radiation during the summer. In addition, the distributions of chemical constituents are related to the gas exchange of oxygen and carbon dioxide between the surface mixed layer and the atmosphere and the high photosynthetic utilization of carbon and nutrients in the surface mixed layer.