Spring carbonate chemistry dynamics of surface waters in the northern East China Sea: Water mixing, biological uptake of CO2, and chemical buffering capacity

We investigated sea surface total alkalinity (TAlk), dissolved inorganic carbon (DIC), dissolved oxygen (DO), and satellite‐derived chlorophyll‐a in the connection between the Yellow Sea and the East China Sea (ECS) during April to early May 2007. In spring, Changjiang dilution water (CDW), ECS offs...

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Bibliographic Details
Published in:Journal of geophysical research. Oceans 2014-09, Vol.119 (9), p.5638-5653
Main Authors: Zhai, Wei-Dong, Chen, Jian-Fang, Jin, Hai-Yan, Li, Hong-Liang, Liu, Jin-Wen, He, Xian-Qiang, Bai, Yan
Format: Article
Language:English
Subjects:
Biogeochemistry
Carbon dioxide
carbonate system
chemical buffering capacity
CO2 uptake
East China Sea
Geophysics
Oceans
water mixing
Yellow Sea
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Summary:We investigated sea surface total alkalinity (TAlk), dissolved inorganic carbon (DIC), dissolved oxygen (DO), and satellite‐derived chlorophyll‐a in the connection between the Yellow Sea and the East China Sea (ECS) during April to early May 2007. In spring, Changjiang dilution water (CDW), ECS offshore water, and together with Yellow Sea water (YSW) occupied the northern ECS. Using 16 day composite satellite‐derived chlorophyll‐a images, several algal blooms were identified in the CDW and ECS offshore water. Correspondingly, biological DIC drawdown of 73 ± 20 μmol kg−1, oversaturated DO of 10–110 μmol O2 kg−1, and low fugacity of CO2 of 181–304 μatm were revealed in these two waters. YSW also showed CO2 uptake in spring, due to the very low temperature. However, its intrusion virtually counteracted CO2 uptake in the northern ECS. In the CDW and the ECS offshore water, Revelle factor was 9.3–11.7 and 8.9–10.6, respectively, while relatively high Revelle factor values of 11.4–13.0 were revealed in YSW. In the ECS offshore water, the observed relationship between DIC drawdown and oversaturated DO departed from the Redfield ratio, indicating an effect of chemical buffering capacity on the carbonate system during air‐sea reequilibration. Given the fact that the chemical buffering capacity slows down the air‐sea reequilibration of CO2, the early spring DIC drawdown may have durative effects on the sea surface carbonate system until early summer. Although our study is subject to limited temporal and spatial coverage of sampling, these insights are fundamental to understanding sea surface carbonate chemistry dynamics in this important ocean margin. Key Points Spring biological drawdown of DIC was estimated in the northern East China Sea The Yellow Sea water intrusion counteracted CO2 uptake in the northern ECS The earlier DIC drawdown had durative effects on carbonate system
ISSN:2169-9275
2169-9291
DOI:10.1002/2014JC009856