PARENT SESSION
Contributed Oral Session 133: Biogeochemistry of Streams and Wetlands
Thursday, August 11, 1:30 PM - 5:00 PM, Meeting Room 516 C, Level 5, Palais des congrès de Montréal
Global patterns and sources of dissolved organic matter export to the coastal zone: Results from a spatially explicit, global model.
Harrison, John*,, Caraco, Nina, Seitzinger, Sybil,
ABSTRACT- Dissolved organic matter (DOM) is a major component of the organic matter transported from terrestrial ecosystems to the coastal zone by rivers, affecting aquatic food webs, the bio-availability of dissolved nutrients and metals, and the optical properties of aquatic systems. Dissolved organic N (DON) and dissolved organic P (DOP) are frequently more abundant than dissolved inorganic nutrient forms. As part of an international, interdisciplinary effort called Global Nutrient Export from Watersheds (Global NEWS), we have developed a system of spatially explicit, global models for predicting river export of three dissolved organic matter (DOM) components: dissolved organic carbon (DOC), DON, and DOP. The DON and DOP models represent the first attempt to model DON and DOP export in a spatially explicit, global manner. DOC, DON, and DOP models explain 88%, 77%, and 91% of the variability in DOC, DON, and DOP yield (kg C, N, or P km-2 yr-1) from validation basins, respectively, and all models are relatively bias-free. When applied globally, these models predict that 170 Tg C yr-1, 10 Tg N yr-1, and 0.6 Tg P yr-1 are exported from terrestrial systems to the coastal zone as DOC, DON, and DOP, respectively. Because predicted spatial patterns of export for DOC, DON, and DOP are all largely driven by water runoff, geographic distribution of high and low fluxes is fairly consistent across elements, with high fluxes of DOC, DON, and DOP generally predicted for high runoff systems and low fluxes predicted for arid systems. However, there are important regional differences in predicted rates of DOC, DON, and DOP export due to anthropogenic inputs of DON and DOP and wetland influence on DOC.
Key words: Dissolved Organic Matter, Rivers, Organic Nitrogen, Organic Phosphorus