Biophysical controls on dissolved organic carbon c

Authors: David V D’Amore Rick T Edwards Frances E Biles

Publish Date: 2015/11/05

Volume: 78, Issue: 2, Pages: 381-393

PDF Link

Abstract

Coastal carbon cycling models remain incomplete in key continental margins worldwide Large quantities of labile terrestrial DOC are transferred to the Gulf of Alaska in a flow of freshwater discharge from thousands of watersheds that equals the discharge of the Mississippi River The coastal margin of southeast Alaska and British Columbia is a potential hotspot of worldwide DOC metabolism and the mass and reactivity of DOC in rivers and estuaries of the region make quantifying and modeling DOC export a priority Scaling DOC export requires a wellconstrained model of streamwater DOC concentrations We established models for prediction of DOC streamwater concentrations through a broad sampling of streams across a large diverse landscape in 61 independent watersheds Stream DOC concentrations were significantly related to the amount of wetlands in a watershed confirming the necessity of understanding the fate of the mass of carbon stored within them Several measures of slope were useful in predictive models of streamwater DOC concentrations suggesting that slope predicts the presence of wetland soils better than current wetland map layers We also provide evidence that suggests watersheds with large salmon spawning runs have distinct characteristics that influence the relationship between wetlands and carbon cycling that may provide additional insights into how carbon is processedWe would like to thank Jacob Berkowitz Erik Norberg Mark Lukey Jason Fellman and Denise Elston for field and laboratory assistance Julianne Thompson Emil Tucker Jackie DeMontigny Aaron Prussian and Katherine Prussian for providing sampling and logistical support for extensive field campaigns and Pat Cunningham for statistical advice Conversations with Tim Max inspired this sample design We would also like to thank Dom Chaloner Chelsea Crenshaw Pat Cunningham and Ashley Steel for constructive comments on early drafts of the manuscript

Keywords: