Collaborative Research: Comprehensive Chemical Characterization of Marine Dissolved Organic Matter using Efficient Isolation Coupled to Advanced Analytical Techniques

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Dissolved organic matter (DOM) plays major roles in oceanic and global biogeochemical processes as it is one of the Earth's largest active carbon pools. Determining the detailed composition and structure of DOM offers unparalleled rewards as their informational richness represents a unique set of biogeochemical tracers capable of providing important insights into the origins of their parent waters and the diagenetic alterations that have occurred within those waters during transport. Recent analytical breakthroughs have the potential to bring a major fraction of marine DOM within our analytical window, thus greatly facilitating the reading of DOM's "molecular messages". In addition, there has been promising improvement in the ability to isolate DOM using reverse osmosis coupled with electrodialysis (RO/ED) that can now isolate up to 95% of marine DOM compared to ~10-40% for previous techniques. In this research, a new investigator from Old Dominion University will lead a team that also includes Georgia Institute of Technology that will combine improved isolation of marine DOM with the unparalleled power of ultra-high resolution FT-ICR MS and advanced NMR spectroscopy to gain major new insights into the composition of marine DOM and the biogeochemical processes controlling its composition. The main goals of this proposed study are to: (1) characterize bio-refractory DOM that dominates the marine DOM pool especially in the deep sea; (2) characterize newly produced DOM in an upwelling region and the semi-biolabile and photobleached DOM that accumulates in oligotrophic, subtropical gyre surface waters; and (3) compare RO/ED isolated DOM to the original sample and to DOM isolated using ultrafiltration and solid-phase extraction (e.g., XAD and C18). In terms of broader impacts, this research will lay the foundations for future oceanic and global biogeochemical studies where these advanced techniques can be used to trace compounds or component classes of DOM from their multifarious sources, along their various paths of diagenesis and transport, to their points of export, microbial uptake or mineralization. In addition, the PIs will provide critically needed precursory reference material for the marine biogeochemical community. The proposed study will support a new Assistant Research Professor at ODU and three doctoral students. Collaborative ties with investigators from WHOI, MIT and the HOT site will foster cooperative field-based research. Public outreach and information dissemination will be facilitated by creation of a dedicated project website and through public and news media interactions, as appropriate.