Refined Estimates of Net Community Production in the Subarctic Northeast Pacific Derived From O-2/Ar Measurements With N2O-Based Corrections for Vertical Mixing
| Type | : | ACL |
|---|---|---|
| Nature | : | Production scientifique |
| Au bénéfice du Laboratoire | : | Non |
| Statut de publication | : | Publié |
| Année de publication | : | 2018 |
| Auteurs (4) | : | IZETT R,w MANNING C,c HAMME Roberta,c TORTELL Philippe,d |
| Revue scientifique | : | Global Biogeochemical Cycles |
| Volume | : | 32 |
| Fascicule | : | 3 |
| Pages | : | 326-350 |
| DOI | : | 10.1002/2017GB005792 |
| URL | : | - |
| Abstract | : | We present the first field application of a N2O-based approach to correct for vertical mixing in the estimation of net community production (NCP) from mixed layer O-2 measurements. Using new ship-based observations of N2O and biological oxygen saturation anomalies (O-2/Ar) from the Subarctic Northeast Pacific, we provide refined mixed layer NCP estimates across contrasting hydrographic regimes and a comprehensive assessment of the methodological considerations and limitations of the approach. Increased vertical mixing coefficients at the base of the mixed layer, derived using N2O measurements, corresponded with periods of heightened wind speed and coastal upwelling. Corrections were most significant in coastal regions where the vertical supply of low-O-2 water can otherwise falsely imply net heterotrophy from negative O-2/Ar measurements. After correcting for the mixing flux, all coastal stations showed autotrophic signatures, with maximum NCP exceeding 100mmolO(2)m(-2)d(-1) in the spring and summer. Vertical fluxes were lower in off-shelf waters but often contributed more than 50% to corrected NCP. At some oceanic stations, however, the cooccurrence of N2O minima and O-2 maxima resulted in biased (overestimated) N2O corrections. Evaluating vertical fluxes in these regions remains a challenge for ship-based studies. Nonetheless, our refined NCP estimates show better coherence with surface chlorophyll, temperature, and mixed layer depth than uncorrected values. Potential mixed layer N2O production introduces some uncertainty in the approach, but errors are likely to be small. Ultimately, this work provides rationale for the adoption of the N2O correction to refine NCP estimates, particularly in coastal waters. |
| Mots-clés | : | BELLINGSHAUSEN SEA; biological oceanography; BIOLOGICAL PRODUCTION; biophysical coupling; EUPHOTIC ZONE; gas tracers; IN-SITU; INTERANNUAL VARIABILITY; NITRIFICATION RATES; NITROUS-OXIDE PRODUCTION; OPEN-OCEAN; PHYTOPLANKTON GROWTH; SITU OXYGEN MEASUREMENTS |
| Commentaire | : | Times Cited in Web of Science Core Collection: 12 |
| Tags | : | - |
| Fichier attaché | : | - |
| Citation | : |
Izett RW, Manning CC, Hamme RC, Tortell PD (2018) Refined Estimates of Net Community Production in the Subarctic Northeast Pacific Derived From O-2/Ar Measurements With N2O-Based Corrections for Vertical Mixing. Global Biogeochem Cy 32: 326-350 | doi: 10.1002/2017GB005792
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