Removal of Refractory Dissolved Organic Carbon in the Amundsen Sea, Antarctica

TitleRemoval of Refractory Dissolved Organic Carbon in the Amundsen Sea, Antarctica
Publication TypeJournal Article
Year of Publication2020
AuthorsFang, L, Lee, SH, Lee, S-A, Hahm, D, Kim, G, Druffel, ERM, Hwang, J
JournalScientific Reports
Date PublishedJan-12-2020
KeywordsCIRCUMPOLAR DEEP-WATER, cycle, DOC, glaciers, INFLOW, MATTER, pacific, phytoplankton, poc, radiocarbon

The removal mechanism of refractory deep-ocean dissolved organic carbon (deep-DOC) is poorly understood. The Amundsen Sea Polynya (ASP) serves as a natural test basin for assessing the fate of deep-DOC when it is supplied with a large amount of fresh-DOC and exposed to strong solar radiation during the polynya opening in austral summer. We measured the radiocarbon content of DOC in the water column on the western Amundsen shelf. The radiocarbon content of DOC in the surface water of the ASP reflected higher primary production than in the region covered by sea ice. The radiocarbon measurements of DOC, taken two years apart in the ASP, were different, suggesting rapid cycling of DOC. The increase in DOC concentration was less than expected from the observed increase in radiocarbon content from those at the greatest depths. Based on a radiocarbon mass balance, we show that deep-DOC is consumed along with fresh-DOC in the ASP. Our observations imply that water circulation through the surface layer, where fresh-DOC is produced, may play an important role in global DOC cycling.