North Atlantic production of nitrous oxide in the context of changing atmospheric levels

Freing, Alina; Wallace, Douglas W.R.; Tanhua, Toste; Walter, S.; Bange, Hermann

North Atlantic production of nitrous oxide in the context of changing atmospheric levels

2009

Freing, Alina | Wallace, Douglas W.R. | Tanhua, Toste | Walter, S. | Bange, Hermann

We use transit time distributions calculated from tracer data together with in situ measurements of N(2)O to estimate the concentration of biologically produced N(2)O ([N(2)O](xs)) and N(2)O production rates in the central North Atlantic Ocean. Our approach to estimation of N(2)O production rates integrates the effects of potentially varying production and decomposition mechanisms along the transport path of a water mass. We find that previously used approaches overestimate the oceanic equilibrium N(2)O concentrations by 8-13% and thus underestimate the strength of N(2)O sources in large parts of the water column. Thus the quantitative characteristics of the [N(2)O](xs)/AOU relationship used as an indicator of nitrification are distorted. We developed a new parameterization of N(2)O production during nitrification depending linearly on AOU and exponentially on temperature and depth, which can be applied to calculate N(2)O production due to nitrification in the entire ocean including oxygen minimum zones.

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