Opsahl, S. National Research Council/U.S.EPA, opsahl.stephen@epa.gov
Benner, R. University of Texas Marine Science Institute, benner@utmsi.utexas.edu
Amon, R. Alfred Wegener Institute for Polar and Marine Research, ramon@awi-bremerhaven.de

Major flux of terrigenous dissolved organic matter through the Arctic Ocean
One of the principle features of the Arctic ecosystem is the immense amount of dissolved organic carbon (25 Tg/y) that is carried by high-latitude rivers to the Arctic Ocean in the form of dissolved organic matter (DOM). We used a combined tracer approach based on the abundance of lignin-a macromolecule unique to vascular plants-and stable carbon isotope ratios to describe the sources of terrigenous DOM to the Arctic Ocean and its distribution in major Arctic Ocean water masses. Lignin oxidation products revealed compositional differences in DOM derived from Arctic drainage basins compared to DOM from temperate and tropical rivers. Concentrations of lignin oxidation products were high in polar surface waters and DOM was depleted in 13-C, indicating much higher concentrations of terrigenous DOM in the surface Arctic Ocean than in the Pacific and Atlantic oceans. A large fraction of terrigenous DOM discharged by rivers to the Arctic Ocean is exported to the North Atlantic via surface waters of the East Greenland Current. In contrast, deep waters from the Arctic Ocean and from throughout the Greenland Gyre had low concentration of terrigenous DOM, indicating minimal contributions of terrigenous DOM during the formation of North Atlantic Deep Water.
Day: Tuesday, Feb. 2
Time: 02:00 - 02:15pm
Location: Eldorado Hotel
Code: SS34TU0200E