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Tidal Marsh Outwelling of Dissolved Carbon and Influences on Optical Properties and Biogeochemical Processes at the Land-Ocean Interface.

Maria Tzortziou, ESSIC, University of Maryland, College Park, MD, USA, maria.a.tzortziou@nasa.gov (Presenter)
Patrick J Neale, Smithsonian Env. Res. Ctr, Edgewater, MD, USA, nealep@si.edu
J Patrick Megonigal, Smithsonian Env. Res. Ctr, Edgewater, MD, USA, megonigalp@si.edu



Coastal wetlands are highly dynamic environments at the land-ocean interface where human activities, short-term physical forcings and intense episodic events result in high biological and chemical variability. Long being recognized as among the most productive ecosystems in the world, tidally-influenced coastal marshes are hot spots of biogeochemical transformation and exchange. The time and space scales of these biogeochemical exchanges however, are poorly constrained. Moreover, relative to information on the amount and direction of carbon and nutrient exchanges, much less is known about the degradability, processing and fate of the distinctive dissolved organic material (DOM) exported from marshes. High resolution observations were performed in freshwater and brackish marsh systems of the Chesapeake Bay and Mid-Atlantic coastal region to characterize carbon exchanges at the marsh-estuary interface and resulting optical, biological and biogeochemical variability. Our results illustrate that the studied tidal marshes are a major source of DOC, DIC and pCO2 to the adjacent estuary and atmosphere, and they trap algae and other suspended particulate matter while they release high molecular-weight, aromatic, humic-rich and optically distinctive colored dissolved organic compounds into the estuary through tidal flushing. Observed gradients in water optical and biogeochemical variables were very consistent among different marsh systems and throughout the year, despite continued tidal exchange, implying rapid transformation of marsh-exported labile DOM in the estuary through both photochemical and microbial processes. Still, the marsh ‘optical signature’ was distinguishable from the regional estuarine background over a distance of more than 1 km into the estuary, suggesting that tidal marsh outwelling of dissolved carbon exerts a strong influence on estuarine optical, biological and biogeochemical variability considerably beyond the marsh-estuary interface. Results from our detailed photochemical degradation and microbial incubation experiments provide insights on the transformation, cycling and fate of marsh-exported dissolved carbon at the land-ocean interface.

Presentation Type:  Poster

Session:  Coupled Processes at Land-Atmosphere-Ocean Interfaces   (Mon 4:00 PM)

Associated Project(s): 

  • Tzortziou, Maria: Spatial and temporal variability of atmospheric NO2 and other trace gases and aerosols over Eastern US coastal regions: applications to remote sensing observations and studies of nitrogen deposition. ...details

Poster Location ID: 89

 


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