Preprints
https://doi.org/10.5194/bg-2019-474
https://doi.org/10.5194/bg-2019-474
16 Dec 2019
 | 16 Dec 2019
Status: this preprint has been withdrawn by the authors.

Acidification-vulnerable carbonate system of the East Sea (Japan Sea)

Taehee Na, Jeomshik Hwang, Soyun Kim, Seonghee Jeong, TaeKeun Rho, and Tongsup Lee

Abstract. The East Sea (Japan Sea) has its own deep overturning circulation, but this operates over a much shorter timescale than that in the open ocean. This allows the East Sea to be used as a natural laboratory in which to investigate potential future changes in the oceanic system. Dissolved inorganic carbon (DIC) and total alkalinity (TA) were measured in 2014 and 2017 to investigate the characteristics and temporal variability of the carbonate system of the East Sea. When the East Sea was compared with a site in the South Atlantic that has similar apparent oxygen utilization (AOU) values, it was also found to have similar DIC content of the deep waters. However, the TA levels in the East Sea were much lower than those recorded in the South Atlantic. Consequently, the DIC / TA ratio of the deep waters of the East Sea was high and similar to that in the North Pacific, which leaves the deep waters of the East Sea vulnerable to acidification by CO2 input. High export production of organic matter, together with low rates of CaCO3 export, are responsible for this high DIC / TA ratio. In the Ulleung Basin, in the southwest of the East Sea, the DIC and AOU of the deep waters increased between 1999 and 2014. pH decrease of the deep waters and shoaling of the carbonate saturation horizons was faster than that recorded in the oceans. Both slowed deep-water ventilation, and the intrusion of anthropogenic CO2 contributed to the acidification of the East Sea. However, a clear increase in DIC from the Japan Basin to the Ulleung Basin, accompanied by a commensurate increase in AOU, was observed in 2014, whereas the meridional gradient was absent in 1999. This observation appears to reflect recent changes in deep-water ventilation, such as the re-initiation of deep-water formation. The East Sea is extremely vulnerable to acidification and should be seen as a special case of ocean acidification rather than an example of how the oceans will respond to a slowdown in ventilation in the future.

This preprint has been withdrawn.

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Taehee Na, Jeomshik Hwang, Soyun Kim, Seonghee Jeong, TaeKeun Rho, and Tongsup Lee

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Interactive discussion

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Taehee Na, Jeomshik Hwang, Soyun Kim, Seonghee Jeong, TaeKeun Rho, and Tongsup Lee
Taehee Na, Jeomshik Hwang, Soyun Kim, Seonghee Jeong, TaeKeun Rho, and Tongsup Lee

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Latest update: 19 May 2024
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Short summary
Acidification of the East Sea (ES) deep waters was occurring at fast rates. A small supply of alkalinity by CaCO3 compared to a large supply of DIC by OM decomposition makes the deep waters of the ES vulnerable to acidification by CO2 input. The water age of the ES deep waters is similar to that in the S. Atlantic. However, DIC / TA ratio is much higher in the ES than that in the S. Atlantic. Recent re-initiation of deep-water formation appears to change the carbonate chemistry of deep waters of ES.
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