Particulate organic carbon sedimentation triggers lagged methane emissions in a eutrophic reservoir Martínez García, Andrés Peralta Maraver, Ignacio Fernando Rodríguez Velasco, Eva Batanero Franco, Gema Laura García Alguacil, Miriam Picazo Mota, Félix Calvo Yagüe, Juan Morales Baquero, Rafael Rueda Valdivia, Francisco José Reche Cañabate, Isabel 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. 2024-05-15T08:51:38Z 2024-05-15T08:51:38Z 2024-03-08 journal article Martínez-García, A., Peralta-Maraver, I., Rodríguez-Velasco, E., Batanero, G.L., García-Alguacil, M., Picazo, F., Calvo, J., Morales-Baquero, R., Rueda, F.J. and Reche, I. (2024), Particulate organic carbon sedimentation triggers lagged methane emissions in a eutrophic reservoir. Limnol. Oceanogr. Lett. https://doi.org/10.1002/lol2.10379 https://hdl.handle.net/10481/91803 10.1002/lol2.10379 eng http://creativecommons.org/licenses/by/4.0/ open access Atribución 4.0 Internacional John Wiley & Sons