|Title||Mesoscale ocean fronts enhance carbon export due to gravitational sinking and subduction|
|Publication Type||Journal Article|
|Year of Publication||2017|
|Authors||Stukel M.R, Aluwihare LI, Barbeau K.A, Chekalyuk A.M, Goericke R, Miller AJ, Ohman MD, Ruacho A., Song H., Stephens B.M, Landry MR|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|Type of Article||Article|
|Keywords||biological carbon pump; california current system; carbon cycle; Coastal upwelling; current ecosystem; pacific-ocean; Particle flux; particle-flux; particulate organic carbon; Plankton; point conception; sea-surface temperature; sediment traps; system; th-234u-238 disequilibria; water column|
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 U-238:Th-234 disequilibrium and sediment traps, we found 2 to 3 times higher rates of gravitational particle export near a deep-water front (305 mg C.m(-2).d(-1)) compared with adjacent water or to mean (nonfrontal) regional conditions. Elevated particle flux at the front wasmechanistically linked to Fe-stressed diatoms and high-mesozooplankton fecal pellet production. Using a data assimilative regional ocean model fit to measured conditions, we estimate that an additional similar to 225 mg C.m(-2).d(-1) was exported as subduction of particle-rich 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.