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| Carter, B. R.; Toggweiler, J. R.; Key, R. M.; Sarmiento, J. L.. |
| We introduce a composite tracer for the marine system, Alk*, that has a global distribution primarily determined by CaCO3 precipitation and dissolution. Alk* is also affected by riverine alkalinity from dissolved terrestrial carbonate minerals. We estimate that the Arctic receives approximately twice the riverine alkalinity per unit area as the Atlantic, and 8 times that of the other oceans. Riverine inputs broadly elevate Alk* in the Arctic surface and particularly near river mouths. Strong net carbonate precipitation results in low Alk* in subtropical gyres, especially in the Indian and Atlantic oceans. Upwelling of dissolved CaCO3-rich deep water elevates North Pacific and Southern Ocean Alk*. We use the Alk* distribution to estimate the variability of... |
| Tipo: Text |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00292/40351/38922.pdf |
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| Straub, M.; Tremblay, M. M.; Sigman, D. M.; Studer, A. S.; Ren, H.; Toggweiler, J. R.; Haug, G. H.. |
| Surface nitrate concentration is a potentially useful diagnostic in reconstructing the past circulation of high-latitude North Atlantic waters. Moreover, nutrient consumption in the North Atlantic surface impacts the atmospheric concentration of carbon dioxide. To reconstruct nutrient conditions in the subpolar North Atlantic region during the last ice age, a record of foraminifera-bound delta N-15 was measured in Neogloboquadrina pachyderma (sin.) from core V28-73 south of Iceland (57.2 degrees N, 20.9 degrees W). Foraminifera-bound delta N-15 is up to 2 parts per thousand lower during the last ice age than during the Holocene, suggesting as much as similar to 25% less complete nitrate consumption during the former. This is consistent with stronger light... |
| Tipo: Text |
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| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00262/37308/35721.pdf |
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