scholarly journals Nitrous oxide distribution and its origin in the central and eastern South Pacific Subtropical Gyre

2007 ◽  
Vol 4 (3) ◽  
pp. 1673-1702 ◽  
Author(s):  
J. Charpentier ◽  
L. Farias ◽  
N. Yoshida ◽  
N. Boontanon ◽  
P. Raimbault
Keyword(s):  
Nitrous Oxide ◽  
Coastal Upwelling ◽  
South Pacific ◽  
Site Preference ◽  
Intermediate Water ◽  
Low Oxygen ◽  
N2o Production ◽  
Oxide Production ◽  
Nitrifier Denitrification ◽  
Nitrous Oxide Production

Abstract. The biogeochemical mechanism of bacterial N2O production in the ocean has been the subject of many discussions in recent years. New isotopomeric tools can help further knowledge on N2O sources in natural environments. This research shows and compares hydrographic, nitrous oxide concentration, and N2O isotopic and isotopomeric data from three stations across the South Pacific Ocean, from the center of the subtropical oligotrophic gyre (~26° S; 114° W) to the upwelling zone along the central Chilean coast (~34° S). Althought AOU/N2O and NO3− trends support the idea that most of N2O source (mainly from intermediate water (200–1000 m)) come from nitrification, N2O isotopomeric composition (intramolecular distribution of 15N isotopes in N2O) reveals an abrupt change in the mechanism of nitrous oxide production, always observed through lower SP (site preference of 15N), at a high – stability layer, where particles could act as microsites and N2O would be produced by nitrifier denitrification (reduction of nitrite to nitrous oxide mediated by primary nitrifiers). There, nitrifier denitrification can account for 40% and 50% (center and east border of the gyre, respectively) of the nitrous oxide produced in this specific layer. This process could be associated with the deceleration of sinking organic particles in highly stable layers of the water column. In constrast, coastal upwelling system is characterized by oxygen deficient condition and some N deficit in a eutrophic system. Here, nitrous oxide accumulates up to 480% saturation, and isotopic and isotopomer signal show highly complex nitrous oxide production processes, which presumably reflect both the effect of nitrification and denitrification at low oxygen levels on N2O production, but non N2O consumption by denitrification was observed.

scholarly journals Nitrous oxide distribution and its origin in the central and eastern South Pacific Subtropical Gyre

2007 ◽  
Vol 4 (5) ◽  
pp. 729-741 ◽  
Author(s):  
J. Charpentier ◽  
L. Farias ◽  
N. Yoshida ◽  
N. Boontanon ◽  
P. Raimbault
Keyword(s):  
Nitrous Oxide ◽  
Coastal Upwelling ◽  
South Pacific ◽  
Site Preference ◽  
Natural Environments ◽  
Intermediate Water ◽  
N2o Production ◽  
South Pacific Ocean ◽  
Nitrifier Denitrification ◽  
Organic Particles

Abstract. 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.

scholarly journals Low nitrous oxide production through nitrifier-denitrification in intermittent-feed high-rate nitritation reactors

2017 ◽  
Vol 123 ◽  
pp. 429-438 ◽  
Author(s):  
Qingxian Su ◽  
Chun Ma ◽  
Carlos Domingo-Félez ◽  
Anne Sofie Kiil ◽  
Bo Thamdrup ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
High Rate ◽  
Oxide Production ◽  
Nitrifier Denitrification ◽  
Nitrous Oxide Production

Nitrification and nitrous oxide production in the offshore waters of the Eastern Tropical South Pacific

2020 ◽  
Author(s):  
Alyson E Santoro ◽  
Carolyn Buchwald ◽  
Angela N Knapp ◽  
William M. Berelson ◽  
Douglas G. Capone ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
South Pacific ◽  
Oxide Production ◽  
Nitrous Oxide Production

scholarly journals Influence of mesoscale eddies on the distribution of nitrous oxide in the eastern tropical South Pacific

2016 ◽  
Vol 13 (4) ◽  
pp. 1105-1118 ◽  
Author(s):  
Damian L. Arévalo-Martínez ◽  
Annette Kock ◽  
Carolin R. Löscher ◽  
Ruth A. Schmitz ◽  
Lothar Stramma ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Water Column ◽  
Coastal Upwelling ◽  
Mesoscale Eddies ◽  
South Pacific ◽  
N Cycling ◽  
Gene Marker ◽  
N Loss ◽  
Mode Water ◽  
N2o Production

Abstract. Recent observations in the eastern tropical South Pacific (ETSP) have shown the key role of meso- and submesoscale processes (e.g. eddies) in shaping its hydrographic and biogeochemical properties. Off Peru, elevated primary production from coastal upwelling in combination with sluggish ventilation of subsurface waters fuels a prominent oxygen minimum zone (OMZ). Given that nitrous oxide (N2O) production–consumption processes in the water column are sensitive to oxygen (O2) concentrations, the ETSP is a region of particular interest to investigate its source–sink dynamics. To date, no detailed surveys linking mesoscale processes and N2O distributions as well as their relevance to nitrogen (N) cycling are available. In this study, we present the first measurements of N2O across three mesoscale eddies (two mode water or anticyclonic and one cyclonic) which were identified, tracked, and sampled during two surveys carried out in the ETSP in November–December 2012. A two-peak structure was observed for N2O, wherein the two maxima coincide with the upper and lower boundaries of the OMZ, indicating active nitrification and partial denitrification. This was further supported by the abundances of the key gene for nitrification, ammonium monooxygenase (amoA), and the gene marker for N2O production during denitrification, nitrite reductase (nirS). Conversely, we found strong N2O depletion in the core of the OMZ (O2 < 5 µmol L−1) to be consistent with nitrite (NO2−) accumulation and low levels of nitrate (NO3−), thus suggesting active denitrification. N2O depletion within the OMZ's core was substantially higher in the centre of mode water eddies, supporting the view that eddy activity enhances N-loss processes off Peru, in particular near the shelf break where nutrient-rich, productive waters from upwelling are trapped before being transported offshore. Analysis of eddies during their propagation towards the open ocean showed that, in general, “ageing” of mesoscale eddies tends to decrease N2O concentrations through the water column in response to the reduced supply of material to fuel N loss, although hydrographic variability might also significantly impact the pace of the production–consumption pathways for N2O. Our results evidence the relevance of mode water eddies for N2O distribution, thereby improving our understanding of the N-cycling processes, which are of crucial importance in times of climate change and ocean deoxygenation.

scholarly journals Comparison of different two-pathway models for describing the combined effect of DO and nitrite on the nitrous oxide production by ammonia-oxidizing bacteria

2016 ◽  
Vol 75 (3) ◽  
pp. 491-500 ◽  
Author(s):  
Longqi Lang ◽  
Mathieu Pocquet ◽  
Bing-Jie Ni ◽  
Zhiguo Yuan ◽  
Mathieu Spérandio
Keyword(s):  
Nitrous Oxide ◽  
Combined Effect ◽  
Ammonia Oxidizing Bacteria ◽  
N2o Production ◽  
Mathematical Structures ◽  
Nitrifier Denitrification ◽  
Nitrous Oxide Production ◽  
Pathway Models ◽  
Microbial Systems ◽  
Electron Carriers

The aim of this work is to compare the capability of two recently proposed two-pathway models for predicting nitrous oxide (N2O) production by ammonia-oxidizing bacteria (AOB) for varying ranges of dissolved oxygen (DO) and nitrite. The first model includes the electron carriers whereas the second model is based on direct coupling of electron donors and acceptors. Simulations are confronted to extensive sets of experiments (43 batches) from different studies with three different microbial systems. Despite their different mathematical structures, both models could well and similarly describe the combined effect of DO and nitrite on N2O production rate and emission factor. The model-predicted contributions for nitrifier denitrification pathway and hydroxylamine pathway also matched well with the available isotopic measurements. Based on sensitivity analysis, calibration procedures are described and discussed for facilitating the future use of those models.

scholarly journals Isotopic evidence for alteration of nitrous oxide emissions and producing pathways contribution under nitrifying conditions

2019 ◽  
Author(s):  
Guillaume Humbert ◽  
Mathieu Sébilo ◽  
Justine Fiat ◽  
Longqi Lang ◽  
Ahlem Filali ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Biofilm Reactor ◽  
Nitrite Reduction ◽  
Nitrous Oxide Emissions ◽  
Site Preference ◽  
N2o Emissions ◽  
Ammonium Oxidation ◽  
N2o Production ◽  
Oxidation Rates ◽  
Nitrifier Denitrification

Abstract. Nitrous oxide (N2O) emissions by a nitrifying biofilm reactor were investigated with N2O isotopocules. The site preference of N2O (15N-SP) indicated the contribution of producing and consuming pathways in response to changes in oxygenation level (from 0 to 21 % O2 in the gas mix), temperature (from 13.5 to 22.3 °C), and ammonium concentrations (from 6.2 to 62.1 mg N L−1). Nitrite reduction, either nitrifier-denitrification or heterotrophic denitrification, was the main N2O producing pathway under the tested conditions. Nitrite oxidation rates decreased as compared to ammonium oxidation rates at temperatures above 20 °C and sub-optimal oxygen levels, increasing N2O production by the nitrite reduction pathway. Below 20 °C, a difference in temperature sensitivity between hydroxylamine and ammonium oxidation rates is most likely responsible for an increase in the N2O production via the hydroxylamine oxidation pathway (nitrification). A negative correlation between the reaction kinetics and the apparent isotope fractionation was additionally shown from the variations of δ15N and δ18O values of N2O produced from ammonium.

scholarly journals Supplementary material to "Regulation of nitrous oxide production in low oxygen waters off the coast of Peru"

2019 ◽  
Author(s):  
Claudia Frey ◽  
Hermann W. Bange ◽  
Eric P. Achterberg ◽  
Amal Jayakumar ◽  
Carolin R. Löscher ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Low Oxygen ◽  
Oxide Production ◽  
Nitrous Oxide Production ◽  
Supplementary Material
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