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Autumn CO 2 chemistry in the Japan Sea and the impact of discharges from the Changjiang River
Author(s) -
Kosugi Naohiro,
Sasano Daisuke,
Ishii Masao,
Enyo Kazutaka,
Saito Shu
Publication year - 2016
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2016jc011838
Subject(s) - alkalinity , oceanography , calcium carbonate , latitude , biogeochemical cycle , carbonate , seawater , calcareous , environmental science , geology , environmental chemistry , chemistry , paleontology , organic chemistry , geodesy
We made comprehensive surface water CO 2 chemistry observations in the Japan Sea during each autumn from 2010 to 2014. The partial pressure of CO 2 ( p CO 2 ) in surface water, 312–329 μatm, was 10–30 μatm lower in the Japan Sea than in the same latitude range of the western North Pacific adjacent to Japan. According to the sensitivity analysis of p CO 2 , the lower p CO 2 in the Japan Sea was primarily attributable to a large seasonal decrease of p CO 2 associated with strong cooling in autumn, particularly in the northern Japan Sea. In contrast, the lower p CO 2 in relatively warm, freshwater in the southern Japan Sea was attributable to not only the thermodynamic effect of the temperature changes but also high total alkalinity. This alkalinity had its origin in Changjiang River and was transported by Changjiang diluted water (CDW) which seasonally runs into the Japan Sea from the East China Sea. The input of total alkalinity through CDW also elevated the saturation state of calcium carbonate minerals and mitigated the effects of anthropogenic ocean acidification, at least during autumn. These biogeochemical impacts of CDW in the Japan Sea last until November, although the inflow from the East China Sea to the Japan Sea almost ceases by the end of September. The long duration of the high saturation state of calcium carbonate benefits calcareous marine organisms.