Dr. Yuting Zhu Marine Chemistry & Geochemistry Woods Hole Oceanographic Institution Mon, 04/22/2024 - 3:30pm Athens Seminars Yuting Zhu is currently a Postdoctoral Investigator in the Department of Marine Chemistry and Geochemistry at Woods Hole Oceanographic Institution and will be joining the Department of Chemistry and Biochemistry at Old Dominion University as an Assistant Professor in July 2024. Title: Photochemical production and microbial cycling of labile organic compounds in seawater The marine dissolved organic carbon (DOC) pool is among the largest carbon reservoirs on Earth and is comparable to the amount of carbon stored in the atmospheric CO2 pool. In the oceanatmosphere system, the flux of carbon through the marine DOC pool is mediated by microbial activity, photochemistry, air-sea exchange, and other processes. In this seminar, I will present a field-based study that provided new insights into the oceanic cycling of acetaldehyde, a carbonyl compound that is a key player in several fundamental biogeochemical processes. These processes include the photochemical degradation of marine DOC, the cycling of labile organic compounds by marine microbes, and the transfer of carbon at the air-sea interface. It is likely that photochemical production and microbial release of acetaldehyde are important sources that balance its microbial consumption in surface seawater. Acetaldehyde is among thousands of labile organic compounds that contribute to the rapid flux of carbon through the marine DOC pool. In oceanic waters, labile organic compounds are present at extremely low concentrations (e.g., picomolar-to-low-nanomolar concentration range) due to their rapid turnover (e.g., from hours to days). The low abundances cause difficulties in the identification and quantification of labile organic compounds in seawater; a major fraction of these compounds is unexplored at the molecular level, and many of their sources and fates remain unknown. In the latter part of the seminar, I will introduce a recently conducted research project that examined amine- and alcoholcontaining metabolites released into seawater by marine phytoplankton. This work advances our current understanding of phytoplankton-derived labile DOC in oceanic waters, unraveling distinct patterns in the composition as well as the abundance of metabolites across taxa. I will finish by briefly highlighting my ongoing and future research plans to further explore the photochemical production and microbial cycling of labile organic compounds in seawater.
