Changing Export of Dissolved Black Carbon from Arctic Rivers

Aron Stubbins, Northeastern University, Marine and Environmental Sciences, Boston, MA, United States, Robert G Spencer, Florida State University, Department of Earth, Ocean & Atmospheric Science, Tallahassee, FL, United States, Dr. Paul James Mann, Northumbria University, Newcastle-Upon-Tyne, United Kingdom, Thorsten Dittmar, University of Oldenburg, Institute for Chemistry and Biology of the Marine Environment (ICBM), Oldenburg, Germany, Jutta Niggemann, Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany, Robert Max Holmes, Woods Hole Research Center, Falmouth, MA, United States and James W McClelland, The Ecosystems Center, Marine Biological Laboratory, Woodshole, United States
Abstract:
Arctic rivers carry black carbon (BC) from Arctic soils to the ocean, linking two of the largest carbon stores on Earth. Wildfires have charred biomass since land plants emerged. BC, a refractory component of char, has accumulated in soils. In the oceans, dissolved BC (DBC) has also accumulated. Here we use samples and data collected as part of the long-term, high temporal resolution Arctic Great Rivers Observatory to model export of DBC from the six largest Arctic Rivers. Scaling to the pan-Arctic catchment, we report that ~3 million tons of DBC are delivered to the Arctic Ocean each year, which is ~8% of dissolved organic carbon loads to the Arctic Ocean. We suggest the transfer of Arctic river DBC to areas of deep water formation is a major source of DBC to the deep ocean carbon store. As the Arctic warms, greater wildfire occurrence is expected to produce more BC and changing hydrology and permafrost thaw to promote DBC export. Thus, the transfer of BC from Arctic soils to the ocean is predicted to increase.
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