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| Titel |
Kinetic bottlenecks to chemical exchange rates for deep-sea animals – Part 2: Carbon Dioxide |
| VerfasserIn |
A. F. Hofmann, E. T. Peltzer, P. G. Brewer |
| 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 ; 10, no. 4 ; Nr. 10, no. 4 (2013-04-11), S.2409-2425 |
| Datensatznummer |
250018193
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| Publikation (Nr.) |
 copernicus.org/bg-10-2409-2013.pdf |
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| Zusammenfassung |
| Increased ocean acidification from fossil fuel CO2 invasion, from
temperature-driven changes in respiration, and from possible leakage from
sub-seabed geologic CO2 disposal has aroused concern over the impacts of
elevated CO2 concentrations on marine life. Discussion of these impacts
has so far focused only on changes in the oceanic bulk fluid properties
(ΔpH, Δ[∑ CO2], etc.) as the critical variable and
with a major focus on carbonate shell formation. Here we describe the rate
problem for animals that must export CO2 at about the same rate at which
O2 is consumed. We analyse the basic properties controlling CO2
export within the diffusive boundary layer around marine animals in an ocean
changing in temperature (T) and CO2 concentration in order to compare
the challenges posed by O2 uptake under stress with the equivalent
problem of CO2 expulsion. The problem is more complex than that for a
non-reactive gas, since with CO2 the influence of the seawater carbonate
acid-base system needs to be considered. These reactions significantly
facilitate CO2 efflux compared to O2 intake at equal temperature,
pressure and fluid flow rate under typical oceanic concentrations. The effect
of these reactions can be described by an enhancement factor, similar to that
widely used for CO2 invasion at the sea surface. While organisms do need
to actively regulate flow over their surface to thin the boundary layer to
take up enough O2, this seems to be not necessary to facilitate CO2
efflux. Instead, the main impacts of rising oceanic CO2 will most likely
be those associated with classical ocean acidification science. Regionally,
as with O2, the combination of T, P and pH/pCO2 creates a
zone of maximum CO2 stress at around 1000 m depth. |
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