Hurricane Harvey brought unprecedented precipitation over an urbanized watershed, causing extensive flooding and delivering a significant pulse of terrigenous material to Galveston Bay. This study employs a comprehensive suite of techniques, including optical spectroscopy, chemical analyses of lignin phenolds and enantiomeric amino acids, and mass spectrometry, to characterize the sources, compositions and transformations of dissolved organic matter (DOM) in response to this extreme weather event.
The results revealed distinct temporal shifts in DOM composition, initially dominated by terrigenous, aromatic-rich constituents shortly after the storm. These compositions transitioned to a more diverse mixture of degraded terrestrial material and phytoplankton-derived autochthonous DOM, driven by extensive microbial processing and the secondary input of bacterial organic matter. This dynamic evolution demonstrates the rapid response of estuarine systems to extreme disturbances, with indications that the bay's ecosystem can recover from episodic events, although the impacts of repeated or sequential disturbances remain uncertain.
The integration of optical, chemical, and mass spectral analyses provided complementary insights into DOM dynamics, highlighting the value of using multiple characterization tools. While chromophoric DOM (CDOM) features and concentrations of biochemicals offered robust indicators of DOM composition, mass spectrometry data further elucidated specific transformation pathways. This comprehensive approach revealed key links between microbial community activity and DOM composition, reflecting preferences for certain DOM components and the influence of nutrient and light conditions. These findings emphasize the profound impacts of extreme weather events on estuarine carbon cycling and biogeochemical dynamics, offering critical insights into the resilience of coastal systems amid increasing climate variability.
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