以乌江为研究对象, 采集了乌江干流 7 座大型水库及猫跳河支流红枫水库的表层水体悬浮颗粒物(total suspended matter, TSM)样品, 测定了其表层颗粒态有机碳(particulate organic carbon, POC)和稳定碳同位素($\delta ^{13}$C), 并以木质素作为陆源有机质的生物标志物, 分析了乌江流域水库有机碳的空间和季节分布特征. 结果表明: 表层水体 TSM 质量浓度受季节影响显著, 呈现出春夏季高于秋冬季的趋势; POC 和木质素含量($\Sigma $8 和 $\Lambda $8)差异受季节影响较大, 其中 秋冬季上游 POC 含量显著高于下游, 体现出梯级筑坝拦截效应; $\Sigma $8 与 $\Lambda $8 呈显著线性相关, 都表现出明显的秋冬季高于春夏季的趋势. 表层水体 TSM 的 $\delta ^{13}$C 值明显偏负, 可能是由于陆源植物碎屑和淡水浮游生物更容易存在于表层水体. 木质素参数信息反映出流域内的优势植被种群为被子植物, TSM 样品的陆源有机质是由多种类型植物共同混合、降解、运输至河流的. TSM 样品的降解水平不高, 7 月、10 月个别采样点出现了较高的降解水平.

Surface water samples were collected from seven cascade reservoirs across the mainstream Wujiang River and Hongfeng Reservoir on the tributary of Maotiao River, to measure the concentration of total suspended matter (TSM). Samples were analysed for elemental and stable carbon isotopic ($\delta ^{13}$C) composition and lignin phenols to investigate the variability in the spatial and seasonal distribution of particulate organic carbon (POC). The TSM in surface water varied greatly across the seasons. It was higher in the spring and summer than in autumn and winter. POC and lignin content ($\Sigma $8 and $\Lambda $8, respectively) in surface water showed high variability that were greatly influenced by season. POC in upstream waters was higher than in downstream waters in the autumn and winter, reflecting dam interception. $\Sigma $8 and $\Lambda $8 in the TSM samples exhibited a significant linear relationship, stronger in autumn and winter than in spring and summer. The $\delta ^{13}$C of TSM was significantly negative. This was potentially due to the more depleted $\delta ^{13}$C of terrestrial plant debris and freshwater plankton, that was likely to exist in surface water. Angiosperms were the dominant vegetation species reflected by lignin. There was a high diversity in the plant sources of terrestrial organic matter in surface particulate matter samples. The extent of degradation of TSM samples was relatively low, and aggravated degradation was observed in July and October, likely related to vigorous microbial activity.