As the largest marginal seas, the Southern Yellow Sea (SYS) and the East China Sea (ECS) are important areas to study the biogeochemical cycles of organic matter from different sources. Seawater samples were collected from the SYS and ECS to determine the composition of organic carbon and major biochemicals (amino acids and carbohydrates) making up the dissolved (DOM) and particulate organic matter (POM). Concentrations of dissolved organic carbon (DOC) in the surface waters exhibited a latitudinal gradient, with high values appearing in the Yellow Sea Coastal Current Water (YSCCW). As the labile fraction of DOM, the concentrations of total hydrolysable amino acids (THAA) and total dissolved carbohydrates (TDCHO) were variable and tended to decrease from inshore to offshore sites. The DOC, THAA, and TDCHO concentrations were negatively correlated with salinity, suggesting that physical mixing and lateral transport played an important role in the distribution of DOM. In contrast, phytoplankton production directly affected the particulate amino acid (PAA) concentrations. High concentrations of PAA in the bottom water along a transect were probably due to resuspension by strong currents. DOC-normalized yields of THAA and TDCHO (THAA-C% and TDCHO-C%) were used to characterize the bioavailability of DOM in different water masses. Elevated THAA-C% values occurred in regions with high phytoplankton biomass, while high TDCHO-C% values were widespread in the Yellow Sea Warm Current Water (YSWCW) and the YSCCW. THAA-C% and TDCHO-C% had similar depth distributions, higher in the surface and middle layers than in the bottom layer, suggesting that organic matter undergoes diagenetic alterations as it sinks. The degradation index (DI) of DOM was lower than that of POM, which could be explained by their different sources and degradation states. The sporadic occurrence of hot spots likely represented important sites of biological activity.

作为最大的边缘海，南黄海（SYS）和东海（ECS）是研究不同来源有机质生物地球化学循环的重要区域。从 SYS 和 ECS 收集海水样品，以确定构成溶解 (DOM) 和颗粒有机物 (POM) 的有机碳和主要生化物质（氨基酸和碳水化合物）的组成。地表水中溶解有机碳 (DOC) 浓度呈现纬度梯度，黄海沿岸流水 (YSCCW) 中出现高值。作为 DOM 的不稳定部分，总水解氨基酸 (THAA) 和总溶解碳水化合物 (TDCHO) 的浓度是可变的，并且从近海到近海有降低的趋势。美国商务部、泰国航空管理局、和 TDCHO 浓度与盐度呈负相关，表明物理混合和横向迁移在 DOM 的分布中起重要作用。相比之下，浮游植物的产生直接影响颗粒氨基酸 (PAA) 浓度。横断面底部水中的高浓度 PAA 可能是由于强流的再悬浮。THAA 和 TDCHO 的 DOC 归一化产量（THAA-C% 和 TDCHO-C%）用于表征不同水团中 DOM 的生物利用度。THAA-C% 值升高发生在浮游植物生物量高的地区，而 TDCHO-C% 值在黄海暖流水 (YSWCW) 和 YSCCW 中普遍存在。THAA-C% 和 TDCHO-C% 具有相似的深度分布，表层和中层高于底层，表明有机物质在下沉时会发生成岩作用。DOM的降解指数（DI）低于POM，这可以用它们不同的来源和降解状态来解释。热点的零星出现可能代表了重要的生物活动场所。