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Provedor de dados:  ArchiMer
País:  France
Título:  Peak glacial C-14 ventilation ages suggest major draw-down of carbon into the abyssal ocean
Autores:  Sarnthein, M.
Schneider, B.
Grootes, P. M.
Data:  2013
Ano:  2013
Resumo:  Ice core records demonstrate a glacial-interglacial atmospheric CO2 increase of similar to 100 ppm, while C-14 calibration efforts document a strong decrease in atmospheric C-14 concentration during this period. A calculated transfer of similar to 530 Gt of C-14-depleted carbon is required to produce the deglacial coeval rise of carbon in the atmosphere and terrestrial biosphere. This amount is usually ascribed to oceanic carbon release, although the actual mechanisms remained elusive, since an adequately old and carbon-enriched deep-ocean reservoir seemed unlikely. Here we present a new, though still fragmentary, ocean-wide Delta C-14 data set showing that during the Last Glacial Maximum (LGM) and Heinrich Stadial 1 (HS-1) the maximum C-14 age difference between ocean deep waters and the atmosphere exceeded the modern values by up to 1500 C-14 yr, in the extreme reaching 5100 C-14 yr. Below 2000 m depth the C-14 ventilation age of modern ocean waters is directly linked to the concentration of dissolved inorganic carbon (DIC). We propose as a working hypothesis that the modern regression of DIC vs. Delta C-14 also applies for LGM times, which implies that a mean LGM aging of similar to 600 (14)Cyr corresponded to a global rise of similar to 85-115 mu mol DIC kg(-1) in the deep ocean. Thus, the prolonged residence time of ocean deep waters may indeed have made it possible to absorb an additional similar to 730-980 Gt DIC, one third of which possibly originated from intermediate waters. We also infer that LGM deep-water O-2 dropped to suboxic values of <10 mu mol kg(-1) in the Atlantic sector of the Southern Ocean, possibly also in the subpolar North Pacific. The deglacial transfer of the extra-aged, deep-ocean carbon to the atmosphere via the dynamic ocean-atmosphere carbon exchange would be sufficient to account for two trends observed, (1) for the increase in atmospheric CO2 and (2) for the 190 parts per thousand drop in atmospheric Delta C-14 during the so-called HS-1 "Mystery Interval", when atmospheric C-14 production rates were largely constant.
Tipo:  Text
Idioma:  Inglês

Editor:  Copernicus Gesellschaft Mbh
Formato:  application/pdf
Fonte:  Climate Of The Past (1814-9324) (Copernicus Gesellschaft Mbh), 2013 , Vol. 9 , N. 6 , P. 2595-2614
Direitos:  Author(s) 2013. CC Attribution 3.0 License.

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