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| Titel |
Efficiency of small scale carbon mitigation by patch iron fertilization |
| VerfasserIn |
J. L. Sarmiento, R. D. Slater, J. Dunne, A. Gnanadesikan, M. R. Hiscock |
| 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. 11 ; Nr. 7, no. 11 (2010-11-12), S.3593-3624 |
| Datensatznummer |
250005059
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| Publikation (Nr.) |
 copernicus.org/bg-7-3593-2010.pdf |
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| Zusammenfassung |
| While nutrient depletion scenarios have long shown that the high-latitude
High Nutrient Low Chlorophyll (HNLC) regions are the most effective for
sequestering atmospheric carbon dioxide, recent simulations with prognostic
biogeochemical models have suggested that only a fraction of the potential
drawdown can be realized. We use a global ocean biogeochemical general
circulation model developed at GFDL and Princeton to examine this and
related issues. We fertilize two patches in the North and Equatorial
Pacific, and two additional patches in the Southern Ocean HNLC region north
of the biogeochemical divide and in the Ross Sea south of the biogeochemical
divide. We evaluate the simulations using observations from both artificial
and natural iron fertilization experiments at nearby locations. We obtain by
far the greatest response to iron fertilization at the Ross Sea site, where
sea ice prevents escape of sequestered CO2 during the wintertime, and
the CO2 removed from the surface ocean by the biological pump is
carried into the deep ocean by the circulation. As a consequence, CO2
remains sequestered on century time-scales and the efficiency of
fertilization remains almost constant no matter how frequently iron is
applied as long as it is confined to the growing season. The second most
efficient site is in the Southern Ocean. The North Pacific site has lower
initial nutrients and thus a lower efficiency. Fertilization of the
Equatorial Pacific leads to an expansion of the suboxic zone and a striking
increase in denitrification that causes a sharp reduction in overall surface
biological export production and CO2 uptake. The impacts on the oxygen
distribution and surface biological export are less prominent at other
sites, but nevertheless still a source of concern. The century time scale
retention of iron in this model greatly increases the long-term biological
response to iron addition as compared with simulations in which the added
iron is rapidly scavenged from the ocean. |
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