 |
| Titel |
Processes determining the marine alkalinity and calcium carbonate saturation state distributions |
| VerfasserIn |
B. R. Carter, J. R. Toggweiler, R. M. Key, J. L. Sarmiento |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 24 ; Nr. 11, no. 24 (2014-12-19), S.7349-7362 |
| Datensatznummer |
250117752
|
| Publikation (Nr.) |
 copernicus.org/bg-11-7349-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| 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 the calcite saturation state resulting from CaCO3 cycling
and other processes. We show that regional differences in surface calcite
saturation state are due primarily to the effect of temperature differences
on CO2 solubility and, to a lesser extent, differences in freshwater
content and air–sea disequilibria. The variations in net calcium carbonate
cycling revealed by Alk* play a comparatively minor role in determining
the calcium carbonate saturation state. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|