ORCID Profile
0000-0001-6659-4284
Current Organisation
海洋研究開発機構
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Publisher: Elsevier BV
Date: 02-2023
Publisher: Springer Science and Business Media LLC
Date: 09-08-2017
DOI: 10.1038/S41598-017-07680-0
Abstract: Marine calcifying organisms, such as stony corals, are under threat by rapid ocean acidification (OA) arising from the oceanic uptake of anthropogenic CO 2 . To better understand how organisms and ecosystems will adapt to or be damaged by the resulting environmental changes, field observations are crucial. Here, we show clear evidence, based on boron isotopic ratio (δ 11 B) measurements, that OA is affecting the pH of the calcification fluid (pH CF ) in Porites corals within the western North Pacific Subtropical Gyre at two separate locations, Chichijima Island (Ogasawara Archipelago) and Kikaijima Island. Corals from each location have displayed a rapid decline in δ 11 B since 1960. A comparison with the pH of the ambient seawater (pH SW ) near these islands, estimated from a large number of shipboard measurements of seawater CO 2 chemistry and atmospheric CO 2 , indicates that pH CF is sensitive to changes in pH SW. This suggests that the calcification fluid of corals will become less supersaturated with respect to aragonite by the middle of this century (pH CF = ~8.3 when pH SW = ~8.0 in 2050), earlier than previously expected, despite the pH CF -upregulating mechanism of corals.
Publisher: Springer Science and Business Media LLC
Date: 25-09-2019
DOI: 10.1038/S41598-019-49739-0
Abstract: The ocean may have played a central role in the atmospheric p CO 2 rise during the last deglaciation. However, evidence on where carbon was exchanged between the ocean and the atmosphere in this period is still lacking, h ering our understanding of global carbon cycle on glacial–interglacial timescales. Here we report a new surface seawater p CO 2 reconstruction for the western equatorial Pacific Ocean based on boron isotope analysis—a seawater p CO 2 proxy—using two species of near-surface dwelling foraminifera from the same marine sediment core. The results indicate that the region remained a modest CO 2 sink throughout the last deglaciation.
Publisher: Springer Science and Business Media LLC
Date: 11-06-2014
DOI: 10.1038/SREP05261
Abstract: While biogeochemical and physical processes in the Southern Ocean are thought to be central to atmospheric CO 2 rise during the last deglaciation, the role of the equatorial Pacific, where the largest CO 2 source exists at present, remains largely unconstrained. Here we present seawater pH and pCO 2 variations from fossil Porites corals in the mid equatorial Pacific offshore Tahiti based on a newly calibrated boron isotope paleo-pH proxy. Our new data, together with recalibrated existing data, indicate that a significant pCO 2 increase (pH decrease), accompanied by anomalously large marine 14 C reservoir ages, occurred following not only the Younger Dryas, but also Heinrich Stadial 1. These findings indicate an expanded zone of equatorial upwelling and resultant CO 2 emission, which may be derived from higher subsurface dissolved inorganic carbon concentration.
Publisher: International Ocean Discovery Program
Date: 30-03-2023
Location: Japan
Location: Japan
Location: No location found
No related grants have been discovered for Kaoru Kubota.