Changing Export of Dissolved Black Carbon from Arctic Rivers

Monday, 15 December 2014
Aron Stubbins1, Robert G Spencer2, Paul James Mann3, Thorsten Dittmar4, Jutta Niggemann4, Robert Max Holmes2 and James W McClelland5, (1)Skidaway Institute of Oceanography, Savannah, GA, United States, (2)Woods Hole Research Center, Falmouth, MA, United States, (3)Northumbria University, Newcastle-Upon-Tyne, NE1, United Kingdom, (4)University of Oldenburg, Oldenburg, Germany, (5)University of Texas Marine Science Institute, Port Aransas, TX, United States
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.