Michiyo Kawai, Associate Professor of the Graduate School of Marine Science and Technology, Tokyokaiyo University, and others, together with Takashi Kikuchi, Deputy Director of the Arctic Environmental Change Research Center of the Ocean Research and Development Organization, surveyed the Chakchi Sea located in the Arctic Ocean on the Pacific Ocean side for two years. ..As a result, it was reported that "ocean acidification" associated with the absorption of anthropogenic carbon dioxide into the ocean is serious near the seabed.
Currently, ocean acidification is progressing as carbon dioxide released by human activities dissolves in seawater throughout the globe, and if this acidification progresses, the calcium carbonate saturation (Ω) of seawater will decrease. It is said that it becomes difficult for organisms to form calcium carbonate shells and skeletons, and when Ω decreases and reaches an "unsaturated" state, calcium carbonate begins to dissolve in seawater.
The cold, low-salt Arctic Ocean is known to be particularly susceptible to acidification, especially in the shallow seabed, where there are many benthic organisms, and a large amount of carbon dioxide is released by the decomposition (breathing) of organic matter. It is characterized by a low Ω of coming seawater.This means that if acidification progresses, calcium carbonate "unsaturated" is likely to be reached.
The Arctic Ocean's Chakchi Sea (water depth of about 50 m), which was investigated, has been observed to reach calcium carbonate "unsaturated" in the summer, but it has been observed by ships in seasons other than the summer. It was not clear because it was difficult.Therefore, Associate Professor Kawai and his colleagues installed various sensors on the seafloor layer of Chakchi and acquired data for two years from 2012 to 2014.As a result of restoring the seasonal change of Ω based on this data, Ω is low not only in summer but also in winter, and it is "unsaturated" for aragonite (calcium carbonate type) for more than 2 months in a year. , It turned out that the situation is such that calcium carbonate dissolves in seawater.
In addition, the period of "unsaturation" has more than doubled compared to the time when there was no anthropogenic carbon dioxide, and there is a possibility that such a situation will become longer and wider in the future. There are concerns about the impact.
This research result was published in the academic journal "Biogeosciences" published by the European Geoscience Union at 11:22 (Japan time) on November 15nd.
