Coupled nitrogen and oxygen isotope measurements of nitrate along the eastern North Pacific margin

Publication Status is "Submitted" Or "In Press: 
LDEO Publication: 
Publication Type: 
Year of Publication: 
2005
Editor: 
Journal Title: 
Global Biogeochemical Cycles
Journal Date: 
Dec 23
Place Published: 
Tertiary Title: 
Volume: 
19
Issue: 
4
Pages: 
-
Section / Start page: 
Publisher: 
ISBN Number: 
0886-6236
ISSN Number: 
Edition: 
Short Title: 
Accession Number: 
ISI:000234364700001
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Call Number: 
Abstract: 

[1] Water column depth profiles along the North Pacific margin from Point Conception to the tip of Baja California indicate elevation of nitrate (NO3-) N-15/N-14 and O-18/O-16 associated with denitrification in the oxygen-deficient thermocline waters of the eastern tropical North Pacific. The increase in delta(18)O is up to 3 parts per thousand greater than in delta(15)N, whereas our experiments with denitrifier cultures in seawater medium indicate a 1: 1 increase in NO3- delta(18)O and delta(15)N during NO3- consumption. Moreover, the maximum in NO3- delta(18)O is somewhat shallower than the maximum in NO3- delta(15)N. These two observations can be summarized as an "anomaly'' from the 1: 1 delta(18)O- to- delta(15)N relationship expected from culture results. Comparison among stations and with other data indicates that this anomaly is generated locally. The anomaly has two plausible interpretations: ( 1) the addition of low-delta(15) N NO3- to the shallow thermocline by the remineralization of newly fixed nitrogen, or ( 2) active cycling between NO3- and NO2- ( coupled NO3- reduction and NO2- oxidation) in the suboxic zone.

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999BWTimes Cited:14Cited References Count:82

DOI: 
Doi 10.1029/2005gb002458