EGU22-8791
https://doi.org/10.5194/egusphere-egu22-8791
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Seawater isotopic measurements (δ18O and δD) reveal significant freshwater influxes into the Arctic seas

Ben Kopec1, Eric Klein2, Shawn Pedron3, Hannah Bailey4, Douglas Causey1, Alun Hubbard5,6, Hannu Marttila7, Kashif Noor7, and Jeffrey Welker1,4,8
Ben Kopec et al.
  • 1Department of Biological Sciences, University of Alaska Anchorage, United States of America
  • 2Department of Geological Sciences, University of Alaska Anchorage, United States of America
  • 3Department of Earth System Science, University of California Irvine, United States of America
  • 4Ecology and Genetics Research Unit, University of Oulu, Finland
  • 5Centre for Arctic Gas Hydrate, Environment and Climate, UiT The Arctic University of Norway, Norway
  • 6Geography Research Unit, University of Oulu, Finland
  • 7Water, Energy and Environmental Engineering, University of Oulu, Finland
  • 8The University of the Arctic (UArctic)

As the Arctic warms, one of the fundamental changes has been the freshening of Arctic ocean waters, impacting ocean circulation and marine ecosystems, among many other critical changes. This increase in freshwater is largely the result of increased precipitation and runoff as part of an amplified Arctic water cycle and increased influx of glacial meltwater from around the Arctic, particularly from the Greenland Ice Sheet. Tracing the sources and extent of this freshwater is critical to understanding future changes to the Arctic seas. One way of delineating these water masses is through measuring its isotopic composition (δ18O and δD), where the freshwater varies significantly from older and other ocean water sources.

In order to identify these freshwater influxes, we conducted in-situ measurements aboard the USCGC Healy that transited the Chukchi and Beaufort Seas, the Northwest Passage, and performed numerous transects across Baffin Bay and the Labrador Sea, including detailed examinations of several key fjords and coastal regions of Greenland, during autumn of 2021. Over the length of this 45 day expedition, we continuously measured the isotopic composition (δ18O and δD) of surface seawater allowing us to fingerprint these sources of freshwater and assess the spatial extent of their influence. We also collected discrete samples from over 100 CTD casts, primarily in Baffin Bay, to identify how freshwater is distributed in the ocean water column. Through these measurements, we identified numerous freshwater influxes, including anomalously high proportions of freshwater in sections of the Beaufort Sea north of Alaska and in Uummannaq Fjord along the west Greenland coast. These isotopic measurements also allow for the disentangling of different freshwater sources (i.e., precipitation or glacial meltwater). Additionally, we find that the freshwater pulses along the west coast of Greenland corresponded with relatively high levels of chlorophyll and fluorescence, suggesting a possible link between this increase in biologic productivity and an increase in the proportion of freshwater.

How to cite: Kopec, B., Klein, E., Pedron, S., Bailey, H., Causey, D., Hubbard, A., Marttila, H., Noor, K., and Welker, J.: Seawater isotopic measurements (δ18O and δD) reveal significant freshwater influxes into the Arctic seas, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8791, https://doi.org/10.5194/egusphere-egu22-8791, 2022.

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