Spatial Patterns of Organic Carbon, Opal and CaCO3 Fluxes in Sediment Traps: Application to the LGM Carbon Cycle.
Abstract
Model studies have shown that possibly the most important factor driving interglacial glacial variations in atmospheric pCO2 is a change in the Particulate Organic Carbon/CaCO3 (POC/PIC) rain ratio to the sediments caused by shifts in the plankton community in surface water. In a study of vertical flux composition from deep-sea sediment traps we show that deep-sea fluxes of organic carbon are linearly related to mineral fluxes opal, CaCO3 and lithogenic material with most of the POC export being associated to the flux of CaCO3 to the deep ocean. We also analyze spatial variability of opal/CaCO3 flux ratios from deep-sea sediment trap experiments in an attempt at parametrising export flux of opal and calcium carbonate. Our results indicates that variability of opal/CaCO3 export fluxes shows different trends depending on region. Comparison between CaCO3 and opal fluxes with environmental parameters points toward the importance of temperature or silica in determining the relation between CaCO3 and opal fluxes. In high latitude regions (mean sea-surface temperatures below 7°C-10°C, silica > 10 μM) the opal/CaCO3 flux ratios increase linearly with opal fluxes In warmer regions (mean sea surface temperature above 7°C-10°C, silica < 10 μM) CaCO3 and opal fluxes are correlated; comparison with environmental conditions indicates that CaCO3 fluxes respond to increases in nutrient availability (including iron deposition) as do opal fluxes. We use the results of the sediment trap analysis to constrain variations in the export production of opal/CaCO3 and organic carbon deposition in deep-sea sediments in a coupled circulation-carbon cycle model LSG-HAMOCC2 and simulate the effect of plankton community changes on glacial/interglacial pCO2 variability.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2002
- Bibcode:
- 2002AGUFMOS52B0219K
- Keywords:
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- 1615 Biogeochemical processes (4805);
- 1635 Oceans (4203);
- 4842 Modeling;
- 4855 Plankton