The Buffering Balance: Modeling Arctic river total-, inorganic-, and organic-alkalinity fluxes

Wednesday, 17 December 2014: 5:00 PM
Christopher W Hunt1,2, Joseph Salisbury2, Wilfred M Wollheim3, Madeleine Mineau2 and Robert James Stewart4, (1)Institute for the Study of Earth, Oceans, and Space, Durham, NH, United States, (2)University of New Hampshire, Durham, NH, United States, (3)Univ New Hampshire, Durham, NH, United States, (4)University of New Hampshire Main Campus, Durham, NH, United States
River-borne inputs of alkalinity influence the pH and pCO2 of coastal ocean waters, and changes in alkalinity inputs also have implications for responses to climate-driven ocean acidification. Recent work has shown that alkalinity fluxes from rivers are not always dominated by inorganic carbon species, and can instead be composed somewhat or mostly of non-carbonate, presumably organic species. Concentrations and proportions of organic alkalinity (O-Alk) are correlated to dissolved organic carbon (DOC) concentrations and fluxes, which are predicted to rise as Arctic permafrost thaws and the hydrologic cycle intensifies. We have scaled results from watershed studies to develop a process-based model to simulate and aggregate Arctic river exports of total alkalinity, DOC, and O-Alk to the coastal sea. Total alkalinity, DOC, and O-Alk were loaded to a river network and routed through a 6-minute hydrologic model (FrAMES). We present results contrasting poorly buffered (e.g. the Kolyma river) and highly buffered (e.g. the Yukon river) systems, the impact of O-Alk on river pH and pCO2, and examine the seasonalities of inorganic and organic influences on coastal ocean carbonate chemistry.