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| Titel |
Calcium carbonate corrosivity in an Alaskan inland sea |
| VerfasserIn |
W. Evans, J. T. Mathis, J. N. Cross |
| 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. 2 ; Nr. 11, no. 2 (2014-01-28), S.365-379 |
| Datensatznummer |
250117148
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| Publikation (Nr.) |
 copernicus.org/bg-11-365-2014.pdf |
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| Zusammenfassung |
| Ocean acidification is the hydrogen ion increase caused by the oceanic uptake
of anthropogenic CO2, and is a focal point in marine biogeochemistry, in
part, because this chemical reaction reduces calcium carbonate (CaCO3)
saturation states (Ω) to levels that are corrosive (i.e., Ω ≤
1) to shell-forming marine organisms. However, other processes can drive
CaCO3 corrosivity; specifically, the addition of tidewater glacial melt.
Carbonate system data collected in May and September from 2009 through 2012
in Prince William Sound (PWS), a semienclosed inland sea located on the
south-central coast of Alaska and ringed with fjords containing tidewater
glaciers, reveal the unique impact of glacial melt on CaCO3 corrosivity.
Initial limited sampling was expanded in September 2011 to span large
portions of the western and central sound, and included two fjords proximal
to tidewater glaciers: Icy Bay and Columbia Bay. The observed conditions in
these fjords affected CaCO3 corrosivity in the upper water column
(< 50 m) in PWS in two ways: (1) as spring-time formation sites of mode
water with near-corrosive Ω levels seen below the mixed layer over a
portion of the sound, and (2) as point sources for surface plumes of glacial
melt with corrosive Ω levels (Ω for aragonite and calcite
down to 0.60 and 1.02, respectively) and carbon dioxide partial pressures
(pCO2) well below atmospheric levels. CaCO3 corrosivity in
glacial melt plumes is poorly reflected by pCO2 or pHT,
indicating that either one of these carbonate parameters alone would fail to
track Ω in PWS. The unique Ω and pCO2 conditions in the
glacial melt plumes enhances atmospheric CO2 uptake, which, if not
offset by mixing or primary productivity, would rapidly exacerbate CaCO3
corrosivity in a positive feedback. The cumulative effects of glacial melt
and air–sea gas exchange are likely responsible for the seasonal reduction of
Ω in PWS, making PWS highly sensitive to increasing atmospheric
CO2 and amplified CaCO3 corrosivity. |
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