Stukel, M. R., L. I. Aluwihare, K. A. Barbeau, A. M. Chekalyuk, R. Goericke,
A. J. Miller, M. D. Ohman, A. Ruacho, H. Song, B. M. Stephens and M. R. Landry, 2017:
Mesoscale ocean fronts enhance carbon export due to gravitational sinking and subduction
Proceedings of the National Academy of Sciences, 114, 1252-1257.
Abstract.
Enhanced vertical carbon transport (gravitational sinking and subduction)
at mesoscale ocean fronts may explain the demonstrated
imbalance of new production and sinking particle export in coastal
upwelling ecosystems. Based on flux assessments from U238:Th234
disequilibrium and sediment traps, we found 2 to 3 times higher
rates of gravitational particle export near a deep-water front
(305 mg C/m2/d) compared with adjacent water or to mean
(nonfrontal) regional conditions. Elevated particle flux at the front
wasmechanistically linked to Fe-stressed diatoms and highmesozooplankton
fecal pellet production. Using a data assimilative regional
ocean model fit to measured conditions, we estimate that an additional
~225 mg C/m2/d was exported as subduction of particlerich
water at the front, highlighting a transport mechanism that is
not captured by sediment traps and is poorly quantified by most
models and in situ measurements. Mesoscale fronts may be responsible
for over a quarter of total organic carbon sequestration in the
California Current and other coastal upwelling ecosystems.
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