Export rates of organic matter (OM) were determined based on PO43−, NO3−and O2budgets during GEOTRACES cruise GP15 in the Pacific Ocean that crossed subpolar, subtropical and equatorial regimes. Lowest OM export rates at 3–5 mmol C/m2/yr were found in the subtropical regions and highest rates at 9–12 mmol C/m2/yr were found in the equatorial and subpolar regions. Satellite based OM export rates showed similar regional trends but with a significantly larger range. The budget and satellite‐based OM export rates were 3–15× higher than estimates of particle loss rates based on234Th and sediment trap collections, with the differences primarily due to non‐particle forms of OM export and different integration times of methods. The efficiency of export varied from 0.1 to 0.3, with the lowest efficiencies in the subtropics and highest efficiencies in the subpolar and equatorial regions.
Multiyear estimates of organic matter (OM) export based primarily on oxygen and dissolved inorganic carbon surface layer budgets applied basin‐wide for the Pacific, Atlantic, and S. Indian Oceans yield an inter‐basin range from 1 to 3 mol C/m2/yr with a global mean of 2.0 mol C/m2/yr (8.5 Gt C/yr). OM export rates per area in the Pacific and Atlantic oceans are twice than that in the Indian Ocean. The supply of nutrients from the Southern Ocean can potentially support ∼70% of the observed OM export in the ocean based on observed surface current velocities and PO4distributions. Horizontal flux of PO4and dissolved organic phosphorous in the surface layer can support ∼50%, 20%, and 15% of observed OM export in the Pacific, S. Indian and Atlantic oceans, respectively, with the remainder being supplied vertically from the subsurface. Potential utilization of unused surface PO4in the subtropical gyre yields ∼0.1 mol C/m2/yr increase in OM export in the Pacific and Atlantic oceans but a ∼0.8 mol C/m2/yr increase in the S. Indian ocean suggesting that stronger nutrient limitation contributes to lower export rates observed in the Indian ocean.
more » « less- PAR ID:
- 10436200
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Global Biogeochemical Cycles
- Volume:
- 37
- Issue:
- 8
- ISSN:
- 0886-6236
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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