Net Community Production derived from DeltaO2/Ar measurements and N2O-based corrections for vertical mixing in the Subarctic Northeast Pacific ...

• Main Authors: Izett, Robert W, Manning, Cara C M, Hamme, Roberta C, Tortell, Philippe Daniel
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA 2018
• Subjects: Subarctic
• Online Access: https://dx.doi.org/10.1594/pangaea.885867; https://doi.pangaea.de/10.1594/PANGAEA.885867

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 O2 measurements. Using new ship-based observations of N2O and biological oxygen saturation anomalies (DeltaO2/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-O2 water can otherwise falsely imply net heterotrophy from negative DeltaO2/Ar measurements. After correcting for the mixing flux, all coastal stations showed autotrophic signatures, with maximum NCP exceeding 100 mmol O2 m-2 day-1 in the spring and summer. ... : Supplement to: Izett, Robert W; Manning, Cara C M; Hamme, Roberta C; Tortell, Philippe Daniel (2018): Refined Estimates of Net Community Production in the Subarctic Northeast Pacific Derived From ΔO2/Ar Measurements With N2O-Based Corrections for Vertical Mixing. Global Biogeochemical Cycles, 32(3), 326-350 ...