Re-evaluating the photochemical sink for terrestrial and marine dissolved organic carbon

Miller and Zepp (1995)* provided the first experimental evidence that the direct abiotic photooxidation of dissolved organic carbon (DOC) to dissolved inorganic carbon (DIC) represents a significant sink for terrestrial DOC in the oceans. Since then, it has largely been assumed that DIC is the primary carbon photoproduct of DOC photochemistry in marine waters. However, direct measurements to support this presumption are lacking. Moreover, the magnitude of the photochemical sink for both terrestrial and marine DOC remains highly uncertain and therefore the importance of sunlight in DOC cycling remains an open question. Here, we present our current understanding of the photochemical sink for DOC from inshore to offshore waters. For the open ocean, it is unclear whether DIC is the main carbon photoproduct of DOC photochemistry. Our results suggest that the photoproduction of low molecular weight organic compounds may dominate in blue waters. Finally, as these products are all biological substrates, we attempt to evaluate whether the photoproduction of these species represents a substantial sink for marine DOC.  *Miller, WL & RG Zepp. 1995. Geophys. Res. Let. 22: 417-420.  

Presentation Preference: Oral

Primary Presenter: Leanne Powers, State University of New York College of Environmental Science and Forestry (lcpowers@esf.edu)

Authors:

William Miller, University of Georgia  (bmiller@uga.edu)

David Kieber, State University of New York College of Environmental Science and Forestry  (djkieber@esf.edu)