Dissolved organic matter (DOM) plays a pivotal role in greenhouse gas (GHGs) production, yet its seasonal evolutionary processes and utilization mechanisms in GHGs production remain poorly understood. This study analyzed the GHG fluxes in conjunction with DOM characterization in sediments by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) and metagenomics to explore the underlying mechanisms in four eutrophic lakes in Wuhan, China. DOM evolved toward a thermodynamically stable state characterized by lower oxidation states and higher saturation levels from spring to winter. Methanogenesis was strictly dependent on specific precursor substrates utilized by methanogens, which required prebiotic degradation processes to generate essential substrates, particularly Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, and Sulfur (CHONPS)-type DOM with low oxidation states and high saturation. In contrast, CO 2 production exhibited broader substrate utilization patterns primarily governed by organic oxidation degree (O/C ratio) and molecular structures. Notably, during denitrification processes, small organic molecules with reduced oxidation states and elevated saturation preferentially facilitated N 2 O reduction to N 2 , resulting in significantly diminished N 2 O fluxes. Collectively, from spring to winter, DOM metabolism in sediments gradually shifted towards prioritizing CH 4 over CO 2 production while promoting N 2 O conversion to N 2 . These findings underscore the critical role of DOM in governing GHGs production differentiation and provide novel insights into understanding GHGs flux dynamics in lake ecosystems.
Zhang et al. (2026) studied this question.