Biogenic sinking particle fluxes and sediment trap collection efficiency at Ocean Station Papa

Comprehensive field observations characterizing the biological carbon pump (BCP) provide foundation needed to constrain mechanistic models of downward particulate organic (POC) flux in ocean. Sediment traps were deployed three times during EXport Processes Ocean from RemoTe Sensing campaign at Station Papa August–September 2018. We propose a new method correct sediment trap sample contamination by zooplankton “swimmers.” consider advantages polyacrylamide gel collectors swimmer influence and estimate magnitude possible biases. Measured fluxes thorium-234 are compared water column measurements assess performance vertically migrating that bypassed traps. found generally low sinking POC (1.38 ± 0.77 mmol C m–2 d–1 100 m, n = 9) included high variable contributions rare, large particles. Sinking particle sizes decreased between 335 m. 234Th smaller than factor approximately 3. Much this difference was consistent with undersampling both small (<32 ?m) particles (>1 mm) active migrant fluxes. The fraction net primary production exported below euphotic zone (0.1% light level; Ez-ratio 0.10 0.06; ratio uncertainties propagated 7–9) prior, late summer studies P, as material m base (T100, 0.55 0.35). While T100 parameters varied weekly, their product, which we interpret overall BCP efficiency, remarkably stable (0.055 0.010), suggesting tight coupling recycling P.