长江口有机碳的时空分异及耦合行为

依据2014年5月、11月于长江口及其邻近海域两个航次的综合环境调查，对颗粒态有机碳（POC）和溶解态有机碳（DOC）在长江口水域的迁移分布及相互转化进行分析。结果表明，长江口DOC和POC浓度整体都遵循南部高、北部低，近岸高、远岸低的分布规律。春季DOC贡献率为18.44%～71.50%，均值为（46.78±13.87）%；秋季为25.46%～84.97%，均值为（63.35±14.63）%。在近岸水域尤其是最大浑浊带（TMZ）附近以POC为主；近海区则以DOC为主，且表层DOC贡献高于底层。长江口水域有机碳物源复杂且主要为陆源输入贡献，底层海洋和三角洲来源的贡献更高。在长江口水域DOC和POC之间存在着形态比例转化，主要受盐度和悬浮颗粒物（TSM）动态变化的控制；当水体中TSM浓度大于98.41 mg/L时，长江口有机碳以颗粒态为主，反之则以溶解态为主。TMZ是有机碳浓度和形态转变的重要场所，POC在此发生沉降并矿化，强水动力导致的解吸和微生物的降解作用可能会促使其向DOC转化。

Spatial-temporal differentiation and coupling behavior oforganic carbon in the Yangtze River Estuary

Based on the comprehensive environmental investigations of the Yangtze River Estuary and its adjacent waters in May and November 2014, the migration, distribution, and mutual transformation of particulate organic carbon (POC) and dissolved organic carbon (DOC) were analyzed. The results showed that the DOC and POC concentrations of the Yangtze River Estuary as a whole follow the distribution pattern of high in the south, low in the north, high inshore areas, and low offshore areas. In spring, the DOC contribution rate of the Yangtze River Estuary ranged from 18.44% to 71.50% with an average of (46.78±13.87)%; in autumn, it varied from 25.46% to 84.97% with an average of (63.35±14.63)%. POC dominated inshore areas, especially near the turbidity maximum zone (TMZ), while DOC dominated offshores. Also, the DOC in the surface water is more advantageous than the bottom water. The organic carbon sources in the Yangtze River Estuary were complex, mainly contributed by terrestrial input sources, while the marine source and the delta source were higher at the bottom. There is a conversion of form ratio between DOC and POC in the Yangtze River Estuary, which is mainly controlled by the dynamical changes of salinity and total suspended matter (TSM) concentrations. When the TSM concentration was greater than 98.41 mg/L, the organic carbon in the Yangtze River Estuary was mainly in particulate, otherwise, it was mainly dissolved. Besides, TMZ played an important role in the transformation of organic carbon concentration and morphology, where POC began deposited and mineralized, as well as desorption caused by strong hydrodynamic forces and microbial degradation may promote its conversion to DOC.