Dispatch 23: Arctic Ocean Acidification     Print

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Mengnan Zhao

October 10, 2015

With decreasing sea-ice cover, the Arctic Ocean is exposed to the atmosphere more than before, which has a potential influence on sea water properties, especially those of the surface mixed layer. For today’s science talk, Michiyo Yamamoto-Kawai, a geochemist from TUMSAT, presented her work on the interannual variability of surface ocean acidification in the Canada Basin.

Ocean acidification has significant influence on Arctic biology by driving corrosion of calcium carbonate (of consequence to organisms with shells). Michiyo has been analyzing the saturation state of aragonite (a type of calcium carbonate) in the upper Beaufort Gyre region for the period 1997 to 2015. This saturation state is influenced by temperature, salinity, carbon dioxide and photosynthesis. From 1997 to 2008, the saturation decreased, which she believes is largely due to the melting of sea ice and increased freshwater. Since 2008, however, the saturation state has been increasing, making marine organisms with shells more vulnerable, and the main contributing factor is believed to be the upper-ocean warming trend. Michiyo’s results demonstrate the importance of other anthropogenic effects on ocean acidification, in addition to the major factor of increasing atmospheric carbon dioxide.

With sea water samples from the Remote Access Sampler (RAS) on the mooring, seasonal variability of the saturation can now be studied in context with other physical and biological processes. This will be investigated by Michiyo’s student Mika Hasegawa, who plans to reconstruct the seasonal aragonite state from RAS data.

Today was a big day for Michiyo because she was awarded the Canadian Department of Fisheries and Oceans Prix d’Excellence 2015 in honor of her contributions to understanding the geochemistry of the Arctic Ocean. Chief Scientist Bill Williams presented her the award during our science meeting. Congratulations, Michiyo!