Student Research Presentations
Time-resolved photochemistry of marine fluorescent dissolved organic matter
ASLO Aquatic Sciences Meeting, Granada, Spain
Marine dissolved organic matter (DOM) is one of the largest carbon reservoirs on Earth, yet much remains unknown about its composition, sources, and degradation. The fraction of DOM that absorbs and emits light in the ultraviolet (UV) and visible light spectrum is referred to as fluorescent DOM (FDOM). In this study, excitation emission matrix (EEM) fluorescence spectroscopy was used to characterize FDOM during photochemical degradation experiments. Prior to photochemical experiments, solid-phase extraction was used to concentrate DOM from six Sargasso Sea water samples collected at the Bermuda Atlantic Time Series Station (BATS) from various depths down to 4537m. Each sample was irradiated for 24 hours using a solar simulator, and EEM spectra were recorded every 20 minutes using a flow cell within a Horiba Aqualog fluorometer and a custom-built flow through irradiation cell. Decrease of four fluorescent peaks and increase of one peak were observed in all samples. A parallel factor analysis (PARAFAC) model was used to determine PARAFAC components that reflect variability of the fluorescence pattern during irradiation experiments and between samples with observed distinct differences between depths.