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TRACING MARINE AND TERRESTRIAL SOURCES OF DISSOLVED ORGANIC MATTER IN THE ARCTIC NEARSHORE ZONE (CANADIAN BEAUFORT SEA)

Organic carbon and nutrients are increasingly mobilized from permafrost coasts due to accelerated coastal erosion in response to Arctic warming. The nearshore zone plays a crucial role in Arctic biogeochemical cycling. Here, terrestrial organic matter degrades into greenhouse gases, releases nutrients, and is buried in nearshore sediments or transported offshore. We present dissolved organic matter (DOM) quantities in surface water in the nearshore zone of the southern Beaufort Sea from three consecutive summer seasons under different meteorological conditions. Colored and fluorescent DOM (cDOM, fDOM) properties are used to differentiate between terrestrial and marine sources. Nearshore dissolved organic carbon (DOC) concentrations vary between about 125 and 420 µmol C L-1. In low salinity conditions between 8 and 15, high DOC concentrations of 290 to 420 µmol C L-1 prevail. Storm events can lead to strongly decreased DOC concentration and increasing salinity (14 to 28) in surface water, probably due to upwelling. In windy and wavy conditions throughout the season, the water column is well-mixed and DOC-poor because saline waters are transported from offshore to nearshore. We recognized a significant negative correlation between DOC and salinity, independent from varying meteorological conditions. Stable stratification in the nearshore zone and calm weather conditions increase the influence of terrestrial-derived DOM and the potential turnover time for biogeochemical cycling in coastal ecosystems. The strength of the terrestrial permafrost influence can be estimated by salinity and stable water isotope techniques as they directly correlate with DOC concentrations.

Authors

Fritz, M., Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Postdam, Germany, Michael.Fritz@awi.de

Tanski, G., Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Postdam, Germany, George.Tanski@awi.de

Gonçalves-Araujo, R., Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany, rafael.goncalves.araujo@awi.de

Heim, B., Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Postdam, Germany, Birgit.Heim@awi.de

Koch, B. P., Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany, Boris.Koch@awi.de

Lantuit, H., Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Postdam, Germany, Hugues.Lantuit@awi.de

Details

Oral presentation

Session #:081
Date: 02/27/2017
Time: 17:15
Location: 313 B

Presentation is given by student: No