Dissolved Organic Matter (DOM) is ubiquitous in natural waters and represents a large, dynamic pool of organic carbon critically important to the global carbon cycle. Coastal marsh-estuary systems are located at the land-ocean interface and receive multiple types of DOM inputs from rivers, salt marshes, bottom sediments, autochthonous primary production, and mixing with the adjacent coastal waters. These systems are also influenced by tides and other physical processes that make them hydrodynamically complex. In these dynamic biogeochemical hotspots, the DOM is typically made up of a very diverse and heterogeneous mixture of compounds with varying reactivities that regulate the extent to which DOM is transformed in the estuary and exported to the adjacent coastal ocean. Predicting the photochemical and biological reactivity of DOM based on its source and degradation state in these complex systems is therefore crucial to understand the fate of organic matter moving across the land-ocean continuum and to accurately estimate carbon export to the coastal ocean. Here, we investigate the relationships between microbial and photochemical reactivities derived from controlled laboratory experiments and indicators of DOM composition, source, and degradation derived from fluorescence, absorption, and high-resolution mass spectrometry. The study focuses on the Plum Island Ecosystems LTER site, a marsh-influenced mesotidal temperate estuary located in coastal Massachusetts, and uses data and samples collected across the system and all seasons.

Primary Presenter: Matthew Weiser, Boston University (mwweiser@bu.edu)

Authors:

Matthew Weiser, Department of Earth and Environment, Boston University  (mwweiser@bu.edu)

Jaydi Swanson, Department of Earth and Environment, Boston University  (jswan22@bu.edu)

Jiyeong Hong, Department of Earth and Environment, Boston University  (jyhong@bu.edu)

Nilotpal Ghosh, Department of Earth and Environment, Boston University  (nghosh@bu.edu)

Karl Kaiser, Department of Marine Science, Texas A&M University at Galveston  (kaiserk@tamug.edu)

Cedric Fichot, Department of Earth and Environment, Boston University  (cgfichot@bu.edu)