Photochemistry of dissolved organic matter (DOM) has gained a lot of momentum in the last two decades. It is well-known as a highly impactful chemical process to DOM being a significant sink for carbon but also able to produce various by-products. Only recently through the development of advanced NMR and ultrahigh resolution mass spectrometry it was possible to start elucidating the compositional changes occurring during photo-irradiation processes and identify structures of the involved molecular species.  Commonly used techniques in photochemical studies are ultraviolet-visible and fluorescence spectroscopies, specific tools for light-reactive species that drive photochemical changes within DOM. The fractions of DOM that are evaluated using these techniques, chromophoric and fluorophoric DOM (CDOM and FDOM, respectively), are operationally defined, and lack information on their molecular composition. For addressing these gaps, we have collected a suite of nine terrestrial blackwater samples to characterize DOM composition, and to evaluate structural changes after photo-irradiation in a solar simulator. We observe high variability in the degrees of photo-degradation, and also a formation of unidentified fluorophore components. Through the use of Principal Component Analysis (PCA), Parallel Factor Analysis (PARAFAC), and Spearman’s Correlation Analysis, we have coupled the optical (UV-VIS and fluorescence spectroscopies) and compositional techniques (NMR spectroscopy and mass spectrometry) to obtain better understanding of the composition and reactivity of CDOM and FDOM in sunlit aquatic environments, providing more information in regards of their biogeochemistry.

Coupling of multivariate statistics and advanced analytical techniques for understanding the composition of terrestrial organic matter and its changes during photo-irradiation

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.