Following the N2O consumption in the oxygen minimum zone of the eastern South Pacific
[摘要] Oxygen minimum zones (OMZs), such as those found in the eastern South Pacific(ESP), are the most important N2O sources in the global ocean relativeto their volume. N2O production is related to low O2 concentrationsand high primary productivity. However, when O2 is sufficiently low,canonical denitrification takes place and N2O consumption can beexpected. N2O distribution in the ESP was analyzed over a widelatitudinal and longitudinal range (from 5° to 30° S and from71–76° to ~ 84° W) based on ~ 890 N2Omeasurements. Intense N2O consumption, driving undersaturations as lowas 40%, was always associated with secondary NO2– accumulation(SNM), a good indicator of suboxic/anoxic O2 levels. First, we explorerelationships between ΔN2O and O2 based on existing data ofdenitrifying bacteria cultures and field observations. Given theuncertainties in the O2 measurements, a second relationship betweenΔN2O and NO2– (> 0.75 μM) was establishedfor suboxic waters (O2 < 8 μM). We reproduced the apparentN2O production (ΔN2O) along the OMZ in ESP with highreliability (r2 = 0.73 p = 0.01). Our results will contribute to thequantification of the N2O that is recycled in O2 deficient waters,and improve the prediction of N2O behavior under future scenarios of OMZexpansion and intensification.
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[效力级别] [学科分类] 地球化学与岩石
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