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| Titel |
The water column distribution of carbonate system variables at the ESTOC site from 1995 to 2004 |
| VerfasserIn |
M. González-Dávila, J. M. Santana-Casiano, M. J. Rueda, O. Llinás |
| 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 ; 7, no. 10 ; Nr. 7, no. 10 (2010-10-11), S.3067-3081 |
| Datensatznummer |
250005009
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| Publikation (Nr.) |
 copernicus.org/bg-7-3067-2010.pdf |
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| Zusammenfassung |
| The accelerated rate of increase in atmospheric carbon dioxide and the
substantial fraction of anthropogenic CO2 emissions absorbed by the
oceans are affecting the anthropocenic signatures of seawater. Long-term
time series are a powerful tool for investigating any change in ocean
bio-geochemistry and its effects on the carbon cycle. We have evaluated the
ESTOC (European Station for Time series in the Ocean at the Canary islands)
observations of measured pH (total scale at 25 °C) and total alkalinity
plus computed total dissolved inorganic carbon concentration (CT) from
1995 to 2004 for surface and deep waters, by following all changes in
response to increasing atmospheric carbon dioxide. The observed values for
the surface partial pressure of CO2 from 1995 to 2008 were also taken
into consideration. The data were treated to better understand the
fundamental processes controlling vertical distributions in the Eastern
North Atlantic Ocean and the accumulation of anthropogenic CO2,
CANT. CT at constant salinity, NCT, increased at a rate of
0.85 μmol kg−1 yr−1 in the mixed layer, linked to an
fCO2 increase of 1.7±0.7 μatm yr−1 in both the atmosphere
and the ocean. Consequently, the mixed layer at ESTOC site has also become
more acidic, −0.0017±0.0003 units yr−1, whereas the carbonate ion
concentrations and CaCO3 saturation states have also decreased over
time. NCT increases at a rate of 0.53, 0.49 and 0.40 μmol kg−1 yr−1
at 300, 600, and 1000 m, respectively. The general
processes controlling the vertical variations of alkalinity and the
inorganic carbon distribution were computed by considering the pre-formed
values, the production/decomposition of organic matter and the
formation/dissolution of carbonates. At 3000 m, 30% of the inorganic
carbon production is related to the dissolution of calcium carbonate,
increasing to 35% at 3685 m. The total column inventory of anthropogenic
CO2 for the decade was 66±3 mol m−2. A model fitting
indicated that the column inventory of CANT increased from 61.7 mol m−2
in the year 1994 to 70.2 mol m−2 in 2004. The ESTOC site is
presented as a reference site to follow CANT changes in the Northeast
Atlantic Sub-tropical gyre. |
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