作者：Franco-Cisterna, B., Carvalho, L., Cross, I.,  et al.

Shallow lakes are increasingly recognized as important sites for organic carbon (OC) storage. However, the drivers of OC deposition in shallow floodplain lakes remain unclear due to complex terrestrial and aquatic interactions. Using 8 yr of monthly sediment trap data in a cross-ecosystem experiment on six UK shallow lakes of varying riverine connectivity, we investigated the role of allochthonous (fluvial materials) vs. autochthonous (phytoplankton production) deposits as the OC supply to lake sediments. Organic carbon sedimentation rates in river-connected (1.3 +/- 1.2 g C m-2 d-1, mean +/- SD) and isolated lakes (0.5 +/- 0.4 g C m-2 d-1) surpassed those previously published for temperate zone eutrophic lakes. Generalized linear mixed-effect models identified water column chlorophyll a as the best predictor of OC sedimentation for most lakes, suggesting that autochthonous phytoplankton production was the dominant driver of OC sedimentation, albeit stimulated by riverine nutrient supply. Carbon (C) transfer to the sediments was modulated by flow; during major floods, phytoplankton was likely flushed out of lakes, reducing OC sedimentation. Inorganic carbon sedimentation intermittently contributes substantially to carbon deposition in spring, summer, and winter. This study evidenced that shallow floodplain lakes are important sites for C deposition, with maximum C transfer to the sediments during the growing season. Future increases in hydrological variability could negatively impact the capacity of shallow floodplain lakes to retain and sequester carbon.

浅水湖泊作为有机碳（OC）储存的重要场所，正日益受到认可。然而，由于复杂的陆地与水生生态系统相互作用，浅滩洪泛区湖泊中有机碳沉积的驱动因素仍不明确。本研究在一项针对英国6个具有不同河流连通性的浅水湖泊开展的跨生态系统实验中，利用8年的月度沉积物捕获器数据，研究了外源（河流物质）与内源（浮游植物生产）沉积物作为湖泊沉积物有机碳来源的作用。连通河流的湖泊（1.3±1.2克碳/平方米/天，平均值±标准差）和孤立湖泊（0.5±0.4克碳/平方米/天）的有机碳沉积速率超过了此前公布的温带富营养化湖泊的数值。广义线性混合效应模型表明，水柱中的叶绿素 a 是大多数湖泊有机碳沉积的最佳预测因子，这意味着内源浮游植物生产是有机碳沉积的主要驱动因素，尽管其受到河流营养供应的刺激。碳（C）向沉积物的转移受到水流的调节；在大洪水期间，浮游植物可能被冲出湖泊，从而减少有机碳的沉积。无机碳沉积在春季、夏季和冬季会间歇性地对碳沉积做出显著贡献。这项研究证明，浅滩洪泛区湖泊是重要的碳沉积场所，在生长季节碳向沉积物的转移量达到最大值。未来水文变异性的增加可能会对浅滩洪泛区湖泊保留和封存碳的能力产生负面影响。

（来源：Limnology and Oceanography 2025  DOI: 10.1002/lno.70199）