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| Titel |
Temporal changes in surface partial pressure of carbon dioxide and carbonate saturation state in the eastern equatorial Indian Ocean during the 1962-2012 period |
| VerfasserIn |
L. Xue, W. Yu, H. Wang, L.-Q. Jiang, L. Feng, L. Gao, K. Li, Z. Li, Q. Wei, C. Ning |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 22 ; Nr. 11, no. 22 (2014-11-21), S.6293-6305 |
| Datensatznummer |
250117683
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| Publikation (Nr.) |
 copernicus.org/bg-11-6293-2014.pdf |
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| Zusammenfassung |
| Information on changes in the oceanic carbon dioxide (CO2) concentration
and air–sea CO2 flux as well as on ocean acidification in the Indian
Ocean is very limited. In this study, temporal changes of the inorganic
carbon system in the eastern equatorial Indian Ocean (EIO, 5° N–5° S, 90–95° E) are examined using partial
pressure of carbon dioxide (pCO2) data collected in May 2012,
historical pCO2 data since 1962, and total alkalinity (TA) data
calculated from salinity. Results show that sea surface pCO2 in the
equatorial belt (2° N–2° S, 90–95° E)
increased from ∼307 μatm in April 1963 to
∼373 μatm in May 1999, ∼381 μatm in
April 2007, and ∼385 μatm in May 2012. The mean rate of
pCO2 increase in this area (∼1.56 μatm yr−1)
was close to that in the atmosphere (∼1.46 μatm yr−1).
Despite the steady pCO2 increase in this region, no significant change
in air–sea CO2 fluxes was detected during this period. Ocean
acidification as indicated by pH and saturation states for carbonate minerals
has indeed taken place in this region. Surface water pH (total hydrogen
scale) and saturation state for aragonite (Ωarag),
calculated from pCO2 and TA, decreased significantly at rates of
−0.0016 ± 0.0001 and −0.0095 ± 0.0005 yr−1,
respectively. The respective contributions of temperature, salinity, TA, and
dissolved inorganic carbon (DIC) to the increase in surface pCO2 and
the decreases in pH and Ωarag are quantified. We find that
the increase in DIC dominated these changes, while contributions from
temperature, salinity, and TA were insignificant. The increase in DIC was
most likely associated with the increasing atmospheric CO2
concentration, and the transport of accumulated anthropogenic CO2 from a
CO2 sink region via basin-scale ocean circulations. These two processes
may combine to drive oceanic DIC to follow atmospheric CO2 increase. |
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