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Nitrous oxide production by nitrification and denitrification in the Eastern Tropical South Pacific oxygen minimum zone
Author(s) -
Ji Qixing,
Babbin Andrew R.,
Jayakumar Amal,
Oleynik Sergey,
Ward Bess B.
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl066853
Subject(s) - denitrification , nitrous oxide , nitrification , nitrate , anoxic waters , nitrite , environmental chemistry , flux (metallurgy) , nitrite reductase , oxygen minimum zone , environmental science , nitrous oxide reductase , nitrogen , chemistry , oxygen , organic chemistry
The Eastern Tropical South Pacific oxygen minimum zone (ETSP‐OMZ) is a site of intense nitrous oxide (N 2 O) flux to the atmosphere. This flux results from production of N 2 O by nitrification and denitrification, but the contribution of the two processes is unknown. The rates of these pathways and their distributions were measured directly using 15 N tracers. The highest N 2 O production rates occurred at the depth of peak N 2 O concentrations at the oxic‐anoxic interface above the oxygen deficient zone (ODZ) because slightly oxygenated waters allowed (1) N 2 O production from both nitrification and denitrification and (2) higher nitrous oxide production yields from nitrification. Within the ODZ proper (i.e., anoxia), the only source of N 2 O was denitrification (i.e., nitrite and nitrate reduction), the rates of which were reflected in the abundance of nirS genes (encoding nitrite reductase). Overall, denitrification was the dominant pathway contributing the N 2 O production in the ETSP‐OMZ.