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PATTERNS AND CONTROLS OF DISSOLVED ORGANIC MATTER EXPORT BY MAJOR RIVERS: A NEW SEASONAL, SPATIALLY EXPLICIT, GLOBAL MODEL
Citation:
McCrackin, M., J. Harrison, AND J. Compton. PATTERNS AND CONTROLS OF DISSOLVED ORGANIC MATTER EXPORT BY MAJOR RIVERS: A NEW SEASONAL, SPATIALLY EXPLICIT, GLOBAL MODEL. Presented at Association for the Science of Limnology and Oceanography, February 17 - 22, 2013.
Impact/Purpose:
Dissolved organic matter (DOM) can have important impacts on nutrient cycles and water quality, yet few models specifically include tracking of dissolved organic forms of carbon, nitrogen or phosphorus. National Research Council post-doc Michelle McCrackin, in conjunction with John Harrison of Washington State University and Jana Compton of the US EPA, has recently developed a global, seasonal model of dissolved organic forms of carbon, nitrogen or phosphorus. Her work illustrates the importance of climate as an influence on DOM transport, and also found that these forms were sometimes decoupled, which has immportant implications for aquatic productivity and water quality.
Description:
River-derived dissolved organic matter (DOM) influences metabolism, light attenuation, and bioavailability of metals and nutrients in coastal ecosystems. Recent work suggests that DOM concentrations in surface waters vary seasonally because different organic matter pools are mobilized during different flow regimes. However, sub-annual patterns and controls on DOM export are poorly understood at large catchment scales. We used measured data from online databases and scientific literature to develop the first global, spatially explicit suite of models called NEWS-DOM-S (Nutrient Export from Watersheds) to predict seasonal export of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and dissolved organic phosphorus (DOP). Contrary to general assumptions, model runs suggested that seasonal DOM cycles were regionally decoupled. For example, seasonal export of DOC, DON, and DOP varied by a factor of 7, 3, and 6, respectively, for boreal and arctic regions and by a factor of 2, 3, and 16, respectively, for tropical regions. DOC, DON, and DOP export were positively related to runoff due to flushing effects. DON export was negatively related to temperature, due likely to biotic processing and uptake.