Using fluorescent dissolved organic matter to trace and distinguish the origin of Arctic surface waters

Rafael Gonçalves-Araujo; Mats A Granskog; Astrid Bracher; Kumiko Azetsu-Scott; Paul A Dodd; Colin A Stedmon

doi:10.1038/srep33978

Using fluorescent dissolved organic matter to trace and distinguish the origin of Arctic surface waters

Sci Rep. 2016 Sep 26:6:33978. doi: 10.1038/srep33978.

Authors

Rafael Gonçalves-Araujo^{1

2

3}, Mats A Granskog⁴, Astrid Bracher^{1

5}, Kumiko Azetsu-Scott⁶, Paul A Dodd⁴, Colin A Stedmon³

Affiliations

¹ Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI), Climate Sciences Division, Physical Oceanography of Polar Seas, Bussestraße 24, 27570 Bremerhaven, Germany.
² University of Bremen, Faculty of Biology and Chemistry (FB2) - PO Box 330440, 28334 Bremen, Germany.
³ Technical University of Denmark, National Institute for Aquatic Resources, Section for Marine Ecology and Oceanography, Kavalergården 6, 2920 Charlottenlund, Denmark.
⁴ Norwegian Polar Institute, Fram Centre, Postbox 6606 Langnes, 9296 Tromsø, Norway.
⁵ University of Bremen, Institute of Environmental Physics, PO Box 330440, 28334 Bremen, Germany.
⁶ Fisheries and Ocean, Canada, Bedford Institute of Oceanography, PO Box 1006, Dartmouth, Nova Scotia, BY2 4A2 Canada.

Abstract

Climate change affects the Arctic with regards to permafrost thaw, sea-ice melt, alterations to the freshwater budget and increased export of terrestrial material to the Arctic Ocean. The Fram and Davis Straits represent the major gateways connecting the Arctic and Atlantic. Oceanographic surveys were performed in the Fram and Davis Straits, and on the east Greenland Shelf (EGS), in late summer 2012/2013. Meteoric (f_mw), sea-ice melt, Atlantic and Pacific water fractions were determined and the fluorescence properties of dissolved organic matter (FDOM) were characterized. In Fram Strait and EGS, a robust correlation between visible wavelength fluorescence and f_mw was apparent, suggesting it as a reliable tracer of polar waters. However, a pattern was observed which linked the organic matter characteristics to the origin of polar waters. At depth in Davis Strait, visible wavelength FDOM was correlated to apparent oxygen utilization (AOU) and traced deep-water DOM turnover. In surface waters FDOM characteristics could distinguish between surface waters from eastern (Atlantic + modified polar waters) and western (Canada-basin polar waters) Arctic sectors. The findings highlight the potential of designing in situ multi-channel DOM fluorometers to trace the freshwater origins and decipher water mass mixing dynamics in the region without laborious samples analyses.