Oxygen minimum zones (OMZs), such as those found in the eastern South Pacific (ESP), are the most important N.sub.2 O sources in the global ocean relative to their volume. N.sub.2 O production is related to low O.sub.2 concentrations and high primary productivity. However, when O.sub.2 is sufficiently low, canonical denitrification takes place and N.sub.2 O consumption can be expected. N.sub.2 O distribution in the ESP was analyzed over a wide latitudinal and longitudinal range (from 5° to 30° S and from 71-76° to ~ 84° W) based on ~ 890 N.sub.2 O measurements. Intense N.sub.2 O consumption, driving undersaturations as low as 40%, was always associated with secondary NO.sub.2 .sup.-- accumulation (SNM), a good indicator of suboxic/anoxic O.sub.2 levels. First, we explore relationships between ΔN.sub.2 O and O.sub.2 based on existing data of denitrifying bacteria cultures and field observations. Given the uncertainties in the O.sub.2 measurements, a second relationship between ΔN.sub.2 O and NO.sub.2 .sup.-- (> 0.75 μM) was established for suboxic waters (O.sub.2 < 8 μM). We reproduced the apparent N.sub.2 O production (ΔN.sub.2 O) along the OMZ in ESP with high reliability (r.sup.2 = 0.73 p = 0.01). Our results will contribute to the quantification of the N.sub.2 O that is recycled in O.sub.2 deficient waters, and improve the prediction of N.sub.2 O behavior under future scenarios of OMZ expansion and intensification.