Controls on deglacial changes in biogenic fluxes in the North Pacific Ocean
The subarctic North Pacific Ocean holds a large CO2 reservoir that is currently isolated from the atmosphereby a low-salinity layer. It has recently been hypothesized that the reorganization of these high-CO2 waters may have played a crucial role in the degassing of carbon dioxide to the atmosphere...
| Published in: | Quaternary Science Reviews |
|---|---|
| Main Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Pergamon-Elsevier Science Ltd
2011
|
| Subjects: | |
| Online Access: | https://doi.org/10.1016/j.quascirev.2011.08.007 http://ecite.utas.edu.au/75120 |
| Summary: | The subarctic North Pacific Ocean holds a large CO2 reservoir that is currently isolated from the atmosphereby a low-salinity layer. It has recently been hypothesized that the reorganization of these high-CO2 waters may have played a crucial role in the degassing of carbon dioxide to the atmosphere duringthe last deglaciation. This reorganization would leave some imprint on paleo-productivity records. Herewe present 230Th-normalized biogenic fluxes from an intermediate depth sediment core in the NorthwestPacific (RC10-196, 54.7degreeN, 177.1degreeE, 1007 m) and place them within the context of a synthesis ofpreviously-published biogenic flux data from 49 deep-sea cores north of 20degreeN, ranging from 420 to3968 m water depth. The 230Th-normalized opal, carbonate, and organic carbon fluxes from RC10-196peak approximately 13,000 calendar years BP during the Bolling/Allerod (B/A) period. Our datasynthesis suggests that biogenic fluxes were in general lowest during the last glacial period, increasedsomewhat in the Northwest Pacific during Heinrich Event 1, and reached a maximum across the entireNorth Pacific during the B/A period. We evaluate several mechanisms as possible drivers of deglacialchange in biogenic fluxes in the North Pacific, including changes in preservation, sediment focusing, seaice extent, iron inputs, stratification, and circulation shifts initiated in the North Atlantic and NorthPacific. Our analysis suggests that while micronutrient sources likely contributed to some of the observedchanges, the heterogeneity in timing of glaciogenic retreat and sea level make these mechanismsunlikely causes of region-wide contemporaneous peaks in export production. We argue that paleoobservationsare most consistent with ventilation increases in both the North Pacific (during H1) andNorth Atlantic (during B/A) being the primary drivers of increases in biogenic flux during the deglaciation,as respectively they were likely to bring nutrients to the surface via increased vertical mixing andshoaling of the global ... |
|---|