Glacial-Interglacial Changes in Export Production in the Subarctic North Pacific Ocean
Abstract
The subarctic North Pacific Ocean is a key region for studying the linkages between circulation, dust, marine productivity, and carbon cycling, because it encompasses a high-nutrient low-chlorophyll region where iron addition experiments and direct observation of dust events have demonstrated its potential to drawdown atmospheric CO2. Furthermore, the deep North Pacific holds a large CO2 reservoir that is currently isolated from the atmosphere by a low-salinity layer, and it has recently been hypothesized that the re-organization of these high-CO2 waters may have played a crucial role in the degassing of carbon dioxide to the atmosphere during the last deglaciation. It is highly likely that this reorganization would leave some imprint on paleo-productivity records. Several studies of deep-sea cores from the North Pacific ocean have demonstrated that export production was greatly reduced during glacial periods. We used 230Th- normalization to reconstruct particle flux to an intermediate depth sediment core. RC10-196 (54.7°N, 177.1°E, 1007 m). This core has sedimentation rates ranging from 3-6 cm/1000 yr during the last 30,000 years. Lithogenic fluxes peak during the height of the last glacial period, while opal and carbonate fluxes peak abruptly on the deglaciation (at approximately 15,000 years ago). The timing of these increases in biogenic fluxes are consistent with those observed in deeper North Pacific cores, and are coincident with abrupt increases in North Pacific temperatures observed at 15,000 years ago. This correlation with temperature and the lack of correspondence between biogenic and lithogenic fluxes suggest that physical conditions may override the role of dust inputs in controlling productivity changes during the last glacial- interglacial transition. These data will be placed in the context of other records generated for the North Pacific Ocean, as part of a regional biogenic flux data synthesis.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFMPP41D1494K
- Keywords:
-
- 0428 Carbon cycling (4806);
- 4900 PALEOCEANOGRAPHY (0473;
- 3344);
- 4912 Biogeochemical cycles;
- processes;
- and modeling (0412;
- 0414;
- 0793;
- 1615;
- 4805);
- 4924 Geochemical tracers;
- 4926 Glacial