Molecular and optical signatures of labile dissolved organic matter during bloom senescence in the Amundsen Sea Polynya
This study investigates DOM dynamics during the late-summer bloom phase dominated by Phaeocystis antarctica in the Amundsen Sea Polynya. By integrating absorbance and fluorescence spectroscopy with FT-ICR-MS, we reveal unique DOM signatures including protein-rich chromophoric DOM with distinct absorbance shoulders, elevated protein-like fluorescent DOM components linked to P. antarctica degradation, and enrichment of labile low-molecular-weight compounds with increased sulfur-containing molecules from DMSP oxidation.