Exact evaluation of gross photosynthetic production from the oxygen triple-isotope composition of O2: Implications for the net-to-gross primary production ratios
Article first published online: 19 JUL 2011
Copyright 2011 by the American Geophysical Union.
Geophysical Research Letters
Volume 38, Issue 14, July 2011
How to Cite
2011), Exact evaluation of gross photosynthetic production from the oxygen triple-isotope composition of O2: Implications for the net-to-gross primary production ratios, Geophys. Res. Lett., 38, L14603, doi:10.1029/2011GL047652., , , and (
- Issue published online: 19 JUL 2011
- Article first published online: 19 JUL 2011
- Manuscript Revised: 26 MAY 2011
- Manuscript Accepted: 26 MAY 2011
- Manuscript Received: 15 APR 2011
- gross primary production (GPP);
- net community production (NCP);
- triple isotopic composition of O2
 The oxygen triple-isotope composition of dissolved O2 provides an integrative method to estimate the rates of Gross Photosynthetic Production (GPP) in the upper ocean, and combined with estimates of Net Community Production (NCP) yields an estimate of the net-to-gross (NCP/GPP) production ratios. However, derivations of GPP from oxygen triple-isotope measurements have involved some mathematical approximations. We derive an exact expression for calculating GPP, and show that small errors associated with approximations result in a relative error of up to ∼38% in GPP, and up to ∼50% in N/G. In open ocean regimes with low primary production, the observed magnitude of the error is comparable to the combined methodological uncertainties. In highly productive ecosystems, the error arising from approximations becomes significant. Using data collected on the Bering Sea shelf, we illustrate the differences in GPP estimates in both high and low productivity regimes that arise from exact and approximated formulations.