Uncovering the Structural Space of Marine Dissolved Organic Matter

Marine dissolved organic matter (DOM) represents one of Earth's most complex exometabolomes, playing a central role in marine carbon cycling and long-term sequestration. Despite its biogeochemical importance, the molecular complexity of DOM has long challenged its analytical characterization. Here, we review recent advancements in structure-resolved analytical techniques for DOM. In addition to spectroscopic methods, we focus on liquid chromatography–tandem mass spectrometry and ion mobility spectrometry, as these technologies can provide unprecedented molecular-level insights into DOM composition. By integrating high-resolution analytical techniques with computational pipelines, researchers are now able to resolve previously obscured molecular structures, which has the potential to refine models of DOM cycling and its interactions with microbial communities. Continued innovation in structure-resolved methodologies will be essential for unraveling the molecular complexity of marine DOM and understanding its implications for global biogeochemical processes.