Premium
Global Nitrous Oxide Production Determined by Oxygen Sensitivity of Nitrification and Denitrification
Author(s) -
Ji Qixing,
Buitenhuis Erik,
Suntharalingam Parvadha,
Sarmiento Jorge L.,
Ward Bess B.
Publication year - 2018
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2018gb005887
Subject(s) - denitrification , nitrous oxide , nitrification , biogeochemical cycle , environmental chemistry , anoxic waters , ammonium , nitrate , chemistry , oxygen , new production , flux (metallurgy) , nitrogen , environmental science , nutrient , organic chemistry , phytoplankton
The ocean is estimated to contribute up to ~20% of global fluxes of atmospheric nitrous oxide (N 2 O), an important greenhouse gas and ozone depletion agent. Marine oxygen minimum zones contribute disproportionately to this flux. To further understand the partition of nitrification and denitrification and their environmental controls on marine N 2 O fluxes, we report new relationships between oxygen concentration and rates of N 2 O production from nitrification and denitrification directly measured with 15 N tracers in the Eastern Tropical Pacific. Highest N 2 O production rates occurred near the oxic‐anoxic interface, where there is strong potential for N 2 O efflux to the atmosphere. The dominant N 2 O source in oxygen minimum zones was nitrate reduction, the rates of which were 1 to 2 orders of magnitude higher than those of ammonium oxidation. The presence of oxygen significantly inhibited the production of N 2 O from both nitrification and denitrification. These experimental data provide new constraints to a multicomponent global ocean biogeochemical model, which yielded annual oceanic N 2 O efflux of 1.7–4.4 Tg‐N (median 2.8 Tg‐N, 1 Tg = 10 12 g), with denitrification contributing 20% to the oceanic flux. Thus, denitrification should be viewed as a net N 2 O production pathway in the marine environment.