Sedimentation of autochthonous labile lipids facilitates methane ebullition

Methane (CH4) emissions from reservoirs contribute largely to global greenhouse gas budgets, with ebullition from sediments being the main pathway. Methanogenesis is the final step in the anaerobic microbial degradation of organic matter, but the specific substrates promoting this step still remain poorly understood. Here, we identify specific lipids in the organic matter from sediment traps during a one-year cycle to further relate them with in-situ CH4 ebullition measurements. Phytol, short-chain n-alkanols, and short-chain fatty acids showed either a strong synchrony or a brief one-week delay to CH4 ebullition peaks, indicating a fast transformation of these substrates by syntrophic microorganisms into precursors of methanogenesis. Phytol sedimentation was strongly coupled to CH4 ebullition, highlighting the importance of this chlorophyll degradation substrate. Also, sedimentation of unsaturated fatty acids from autochthonous algae and zooplankton was synchronized with CH4 ebullition..., , # Sedimentation of autochthonous labile lipids facilitates methane ebullition **AUTHORS:** Andrés Martínez-García, Ignacio Peralta-Maraver, Miriam García-Algualcil, Eva Rodríguez-Velasco, Marta Rodrigo-Gámiz, Sebastian Naeher, Isabel Reche **FILES:** Contains 3 files: **1. code_lipids.R** - R script to replicate analyses and the figures, including: Figure 2: Time series showing how the Methane Index and the GDGT/Crenarchaeol ratio relateto methane emissions over time Figure 3: Specific lipids vs. methane representation, and correlation values Figure 4: PCA of lipid profiles and methane ebullition Figure 5: Visualizing model terms **2. Dataset** with two different .xlsx documents 2.1. data.xlsx - time_series: Contains information of the sampled variables during the study period. **Columns**: date: date of sampling C12_OH: C-12 n-alkanol sedimentation flux C13_OH: C-13 n-alkanol sedimentation flux C14_OH: C-14 n-alkanol sedimentation flux C15_OH: C-15 n-alkanol sedimentation flu..., , **Changes after Jan 5, 2026:**  Added an additional column containing particulate organic carbon (POC) sedimentation rate, used for graphical representation