Anthropogenic carbon changes in the Irminger Basin (1981-2006): Coupling δ 13 C DIC and DIC observations
International audience The North Atlantic subpolar gyre is considered to be one of the strongest marine anthropogenic CO 2 sinks, a consequence of extensive deep convection occurring during winter. Observations collected in this region since 1981 have shown large changes in Dissolved Inorganic Carbo...
Published in: | Journal of Marine Systems |
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Main Authors: | , , , , , , , , , |
Other Authors: | , , , , , , , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2013
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Subjects: | |
Online Access: | https://hal.archives-ouvertes.fr/hal-00873502 https://doi.org/10.1016/J.JMARSYS.2012.12.005 |
Summary: | International audience The North Atlantic subpolar gyre is considered to be one of the strongest marine anthropogenic CO 2 sinks, a consequence of extensive deep convection occurring during winter. Observations collected in this region since 1981 have shown large changes in Dissolved Inorganic Carbon (DIC) concentrations in intermediate and deep waters, which have been attributed to both anthropogenic CO 2 penetration and natural variability in the ocean carbon cycle (Wanninkhof et al., 2010). In this context, we describe new δ 13 C DIC observations obtained in the Irminger Basin during two OVIDE cruises (2002 and 2006) which we compare to historical data (TTO-NAS 1981) in order to estimate the oceanic 13 C Suess Effect over the more than twenty years that separates these surveys. The data reveal a significant decrease in δ 13 C DIC , of between - 0.3‰ and - 0.4‰ from 1981 to 2006. The anthropogenic change, extracted by using the extended Multi Linear Regression (eMLR) approach, explains 75% of this signal for oldest water mass and 90% for youngest. The reminding signal is due to the natural processes, such as remineralization and vertical mixing. The eMLR method was also applied to DIC measurements which i) reveal strong relationships between the increase of anthropogenic CO 2 and the oceanic 13 C Suess Effect over the whole water column during the 25-year period and ii) support the hypothesis of change in the Cant storage rate in the Irminger Basin between 1981 and 2006. |
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