Abstract The components, sources, and seasonal and spatial changes of fluorescent dissolved organic matter (FDOM) in the continental shelf area of the East China Sea (ECS), were determined by excitation and emission matrices (EEM) spectroscopy and parallel factor analysis (PARAFAC). The PARAFAC model identified four FDOM components from 234 samples in June and October 2014. The four components consisted of three terrestrial humic-like components (C1, C2, and C3) and one tryptophan-like component (C4). Based on the spatial and seasonal distributions, as well as their correlations with salinity, chlorophyll a (chl a), and apparent oxygen utilization, the following assignments were made: C1, C2, and C3 originated mainly from terrestrial inputs and could also be affected by phytoplankton and microbial activity; C4 was a result of allochthonous and autochthonous sources and was a biologically labile component. In most of the study area, the fluorescence intensities of FDOM were higher in June than in October. Terrestrial inputs, anthropogenic activity, and autochthonous sources could affect the seasonal and spatial variations of FDOM. Allochthonous sources were the main factors influencing FDOM in the continental shelf area of the ECS. The higher fluorescence index and lower humification index in June demonstrated that FDOM had increased autochthonous production and a lower degree of humification. The effect of photodegradation was also stronger in June.

中文翻译：

---

东海大陆架区FDOM组成的季节和空间变化

摘要 利用激发发射矩阵 (EEM) 光谱和平行因子分析 (PARAFAC) 确定了东海 (ECS) 大陆架区荧光溶解有机质 (FDOM) 的成分、来源以及季节和空间变化。 ）。PARAFAC 模型从 2014 年 6 月和 2014 年 10 月的 234 个样本中识别出四种 FDOM 成分。这四种成分包括三种陆地腐殖质类成分（C1、C2 和 C3）和一种色氨酸类成分（C4）。根据空间和季节分布，以及它们与盐度、叶绿素 a (chl a) 和表观氧利用的相关性，做出以下分配： C1、C2 和 C3 主要来自陆地输入，也可能受到影响通过浮游植物和微生物活动；C4 是异地和本土来源的结果，是一种生物不稳定的成分。在大部分研究区，6 月份 FDOM 的荧光强度高于 10 月份。陆地输入、人为活动和本土来源可能影响 FDOM 的季节和空间变化。外来源是影响ECS大陆架区FDOM的主要因素。6 月份较高的荧光指数和较低的腐殖化指数表明 FDOM 增加了本地生产和较低的腐殖化程度。6 月份光降解的影响也更强。和本土来源可能会影响 FDOM 的季节和空间变化。外来源是影响ECS大陆架区FDOM的主要因素。6 月份较高的荧光指数和较低的腐殖化指数表明 FDOM 增加了本地生产和较低的腐殖化程度。6 月份光降解的影响也更强。和本土来源可能会影响 FDOM 的季节和空间变化。外来源是影响ECS大陆架区FDOM的主要因素。6 月份较高的荧光指数和较低的腐殖化指数表明 FDOM 增加了本地生产和较低的腐殖化程度。6 月份光降解的影响也更强。