Reservoirs act as carbon sinks when sedimentation of particulate organic carbon (POC) exceeds CO2 and CH4 emissions. Here, we study the poorly explored process where phytoplankton‐derived acidic polysaccharides (APs) aggregate into particulate organic matter, promoting carbon export to sediments. This source of POC in sediments can mineralize to CO2 and CH4 over various timescales. Our research, centered on a Mediterranean reservoir, elucidates phenological trends of APs and POC sedimentation and identifies their predominant drivers. Our findings present synchronic sedimentation patterns of POC and APs but identify a 2‐week delay between POC sedimentation and CH4 emissions. Despite its eutrophic status, our data demonstrate this reservoir's role as a carbon sink, sequestering 4.33 g C m−2 yr−1. This highlights the need to consider various time scales when quantifying carbon budgets in reservoirs.

中文翻译：

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颗粒有机碳沉积引发富营养化水库滞后甲烷排放

当颗粒有机碳 (POC) 沉降超过 CO 时，水库充当碳汇2和CH4排放。在这里，我们研究了一个鲜为人知的过程，即浮游植物衍生的酸性多糖（AP）聚集成颗粒有机物，促进碳输出到沉积物。沉积物中的 POC 来源可以矿化为 CO2和CH4在不同的时间尺度上。我们的研究以地中海水库为中心，阐明了 AP 和 POC 沉积的物候趋势，并确定了其主要驱动因素。我们的研究结果呈现了 POC 和 AP 的同步沉降模式，但发现 POC 沉降和 CH 之间有 2 周的延迟4排放。尽管处于富营养化状态，但我们的数据表明该水库具有碳汇作用，封存了 4.33 g C m−2年−1。这突出表明在量化水库碳预算时需要考虑不同的时间尺度。