 |
| Titel |
Nitrous oxide distribution and its origin in the central and eastern South Pacific Subtropical Gyre |
| VerfasserIn |
J. Charpentier, L. Farías, N. Yoshida, N. Boontanon, P. Raimbault |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 4, no. 5 ; Nr. 4, no. 5 (2007-09-13), S.729-741 |
| Datensatznummer |
250001957
|
| Publikation (Nr.) |
 copernicus.org/bg-4-729-2007.pdf |
|
|
|
|
|
| Zusammenfassung |
| The mechanisms of microbial nitrous oxide (N2O) production in the ocean
have been the subject of many discussions in recent years. New isotopomeric
tools can further refine our knowledge of N2O sources in natural
environments. This study compares hydrographic, N2O concentration, and
N2O isotopic and isotopomeric data from three stations along a
coast-perpendicular transect in the South Pacific Ocean, extending from the
center (Sts. GYR and EGY) of the subtropical oligotrophic gyre (~26° S; 114° W) to the upwelling zone (St. UPX) off the central
Chilean coast (~34° S). Although AOU/N2O and NO3−
trends support the idea that most of the N2O (mainly from intermediate
water (200–600 m)) comes from nitrification, N2O isotopomeric
composition (intramolecular distribution of 15N isotopes) expressed as
SP (site preference of 15N) shows low values (10 to 12\permil) that could be
attributed to the production through of microbial nitrifier denitrification
(reduction of nitrite to N2O mediated by ammonium oxidizers). The
coincidence of this SP signal with high – stability layer, where sinking
organic particles can accumulate, suggests that N2O could be produced
by nitrifier denitrification inside particles. It is postulated that
deceleration of particles in the pycnocline can modify the advection -
diffusion balance inside particles, allowing the accumulation of nitrite and
O2 depletion suitable for nitrifier denitrication. As lateral advection
seems to be relatively insignificant in the gyre, in situ nitrifier
denitrification could account for 40–50% of the N2O produced in this
layer. In contrast, coastal upwelling system is characterized by O2
deficient condition and some N deficit in a eutrophic system. Here, N2O
accumulates up to 480% saturation, and isotopic and isotopomer signals
show highly complex N2O production processes, which presumably reflect
both the effect of nitrification and denitrification at low O2 levels
on N2O production, but net N2O consumption by denitrification was
not observed. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|