scholarly journals Biogeochemical controls and isotopic signatures of nitrous oxide production by a marine ammonia-oxidizing bacterium

2010 ◽  
Vol 7 (2) ◽  
pp. 3019-3059 ◽  
Author(s):  
C. H. Frame ◽  
K. L. Casciotti
Keyword(s):  
Nitrous Oxide ◽  
Stratospheric Ozone ◽  
N2o Production ◽  
Isotopic Signatures ◽  
Ammonium N ◽  
O2 Concentration ◽  
Nitrous Oxide Production ◽  
Global Estimates ◽  
Cell Densities ◽  
Ammonia Oxidizing Bacterium

Abstract. Nitrous oxide (N2O) is a trace gas that contributes to greenhouse warming of the atmosphere and stratospheric ozone depletion. The N2O yield from nitrification (moles N2O-N produced/mole ammonium-N consumed) has been used to estimate marine N2O production rates from measured nitrification rates and global estimates of oceanic export production. However, the N2O yield from nitrification is not constant. Previous culture-based measurements indicate that N2O yield increases as oxygen (O2) concentration decreases and as nitrite (NO2−) concentration increases. These results were obtained in substrate-rich conditions and may not reflect N2O production in the ocean. Here, we have measured yields of N2O from cultures of the marine β-proteobacterium Nitrosomonas marina C-113a as they grew on low-ammonium (50 μM) media. These yields were lower than previous reports, between 4×10−4 and 7×10−4 (moles N/mole N). The observed impact of O2 concentration on yield was also smaller than previously reported under all conditions except at high starting cell densities (1.5×10

scholarly journals Biogeochemical controls and isotopic signatures of nitrous oxide production by a marine ammonia-oxidizing bacterium

2010 ◽  
Vol 7 (9) ◽  
pp. 2695-2709 ◽  
Author(s):  
C. H. Frame ◽  
K. L. Casciotti
Keyword(s):  
Nitrous Oxide ◽  
Stratospheric Ozone ◽  
Nitrifying Bacteria ◽  
Site Preference ◽  
Ammonia Oxidizing Bacteria ◽  
N2o Production ◽  
O2 Concentration ◽  
Cell Densities ◽  
Dissolved O2

Abstract. Nitrous oxide (N2O) is a trace gas that contributes to the greenhouse effect and stratospheric ozone depletion. The N2O yield from nitrification (moles N2O-N produced per mole ammonium-N consumed) has been used to estimate marine N2O production rates from measured nitrification rates and global estimates of oceanic export production. However, the N2O yield from nitrification is not constant. Previous culture-based measurements indicate that N2O yield increases as oxygen (O2) concentration decreases and as nitrite (NO2−) concentration increases. Here, we have measured yields of N2O from cultures of the marine β-proteobacterium Nitrosomonas marina C-113a as they grew on low-ammonium (50 μM) media. These yields, which were typically between 4 × 10−4 and 7 × 10−4 for cultures with cell densities between 2 × 102 and 2.1 × 104 cells ml−1, were lower than previous reports for ammonia-oxidizing bacteria. The observed impact of O2 concentration on yield was also smaller than previously reported under all conditions except at high starting cell densities (1.5 × 106 cells ml−1), where 160-fold higher yields were observed at 0.5% O2 (5.1 μM dissolved O2) compared with 20% O2 (203 μM dissolved O2). At lower cell densities (2 × 102 and 2.1 × 104 cells ml−1), cultures grown under 0.5% O2 had yields that were only 1.25- to 1.73-fold higher than cultures grown under 20% O2. Thus, previously reported many-fold increases in N2O yield with dropping O2 could be reproduced only at cell densities that far exceeded those of ammonia oxidizers in the ocean. The presence of excess NO2− (up to 1 mM) in the growth medium also increased N2O yields by an average of 70% to 87% depending on O2 concentration. We made stable isotopic measurements on N2O from these cultures to identify the biochemical mechanisms behind variations in N2O yield. Based on measurements of δ15Nbulk, site preference (SP = δ15Nα−δ15Nβ), and δ18O of N2O (δ18O-N2O), we estimate that nitrifier-denitrification produced between 11% and 26% of N2O from cultures grown under 20% O2 and 43% to 87% under 0.5% O2. We also demonstrate that a positive correlation between SP and δ18O-N2O is expected when nitrifying bacteria produce N2O. A positive relationship between SP and δ18O-N2O has been observed in environmental N2O datasets, but until now, explanations for the observation invoked only denitrification. Such interpretations may overestimate the role of heterotrophic denitrification and underestimate the role of ammonia oxidation in environmental N2O production.

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.

Nitrogen turnover and N2O production in incubated soils after receiving field applications of liquid manure and nitrification inhibitors

2021 ◽  
Author(s):  
Sisi Lin ◽  
Guillermo Hernandez-Ramirez
Keyword(s):  
Nitrous Oxide ◽  
Nitrification Rate ◽  
N2o Emissions ◽  
Nitrification Inhibitors ◽  
Nitrogen Transformations ◽  
Liquid Manure ◽  
N2o Production ◽  
N Transformations ◽  
Nitrous Oxide Production ◽  
Time Courses

Applying abundant manure to soils can accelerate nitrogen transformations and nitrous oxide (N2O) emissions. We conducted a laboratory incubation to examine the turnover of labile N in manured soils. Soils were collected from agricultural fields that had recently received spring-injected liquid manure with or without admixing nitrification inhibitors. Bands and interbands of the manure plots were incubated separately. Time courses of ammonium (NH4+) and nitrate (NO3-) were used to derive and contrast zero-, first- and second-order kinetics models. We found that nitrification rates were consistently better represented by first-order kinetics (k1). Furthermore, across all evaluated soils, the dependency of nitrification rate (k1 of NH4+) on initial NH4+ concentration was modelled by Michaelis-Menten kinetics reasonably well, with an affinity (Km) of 63 mg N kg-1 soil (R2= 0.82). Compared to the manure interbands, the initially NH4-enriched bands had a much faster nitrification rate, with half-life for NH4+ of only 4 days and rapid k1 (0.186 versus 0.011 day-1). Soil N substrate and k1 exerted control on N2O production. Nitrous oxide production increased linearly with both measured NH4+ intensity (R2= 0.47) and modelled k1–NH4+ (R2= 0.48). Conversely, N2O production increased non-linearly with NO3- intensity (R2= 0.68), where high NO3- caused a saturation plateau with a threshold of 96 mg N kg-1 day-1 – beyond which no additional N2O was produced. During peak N transformations, measured N2O-N flux was 1.4±0.3% of the inorganic N undergoing nitrification. Heavily manured soils exhibited augmented N turnover that increased N2O fluxes, but inhibitors reduced these emissions by half.

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.

Identification of regulatory genes to reduce N2O production

2014 ◽  
Vol 94 (6) ◽  
pp. 1033-1036 ◽  
Author(s):  
Steven D. Siciliano
Keyword(s):  
Nitrous Oxide ◽  
Microbial Activity ◽  
Agricultural Soil ◽  
Agricultural Soils ◽  
Regulatory Genes ◽  
N2o Production ◽  
Agricultural Ecosystems ◽  
Nitrous Oxide Production ◽  
Net Flux ◽  
Sequential Reduction

Siciliano, S. D. 2014. Identification of regulatory genes to reduce N2O production. Can. J. Plant Sci. 94: 1033–1036. The production of nitrous oxide occurs predominantly by microbial activity. This microbial activity can be broadly sub-divided into denitrification, the sequential reduction of nitrate to nitrous oxide or dinitrogen gas, or into nitrification, the sequential oxidation of ammonia to nitrite. The consumption of nitrous oxide occurs by microbial activity as well, but only by a single pathway, i.e., the activity of nitrous oxide reductase (nos). The purpose of this investigation was to determine the dominant producer of nitrous oxide in our agricultural ecosystems, and then explore how these producers interacted with other biological and edaphic factors to regulate overall nitrous oxide production. Finally, we also investigated what controlled nitrous oxide consumption in these agricultural ecosystems. Much to our surprise, the dominant production of nitrous oxide in these upland agricultural soils occurred by nitrification, likely the nitrification-denitrification pathway. In addition, a root exudate, formate, was a large driver of nitrous oxide release via its interaction with the fungal biomass under micro-aerophilic conditions. Despite these unusual sources of production, what became apparent was that the net flux of nitrous oxide in an agricultural soil was linked to denitrifier consumption of nitrous oxide. In conclusion, this project found that there was a wide variety of non-bacterial denitrifier producers of nitrous oxide in an agricultural soil and that they interact not only between themselves but with the plant community. However, the net production of nitrous oxide in agricultural fields was still tightly linked to bacterial denitrification, but through the consumption of nitrous oxide by bacterial denitrifiers.

scholarly journals Biological nitrous oxide consumption in oxygenated waters of the high latitude Atlantic Ocean

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Andrew P. Rees ◽  
Ian J. Brown ◽  
Amal Jayakumar ◽  
Gennadi Lessin ◽  
Paul J. Somerfield ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Atlantic Ocean ◽  
High Latitude ◽  
Bacterial Communities ◽  
Stratospheric Ozone ◽  
Intermediate Step ◽  
Anoxic Environments ◽  
Production And Consumption ◽  
Net Flux ◽  
Traditional Understanding

AbstractNitrous oxide (N2O) is important to the global radiative budget of the atmosphere and contributes to the depletion of stratospheric ozone. Globally the ocean represents a large net flux of N2O to the atmosphere but the direction of this flux varies regionally. Our understanding of N2O production and consumption processes in the ocean remains incomplete. Traditional understanding tells us that anaerobic denitrification, the reduction of NO3− to N2 with N2O as an intermediate step, is the sole biological means of reducing N2O, a process known to occur in anoxic environments only. Here we present experimental evidence of N2O removal under fully oxygenated conditions, coupled with observations of bacterial communities with novel, atypical gene sequences for N2O reduction. The focus of this work was on the high latitude Atlantic Ocean where we show bacterial consumption sufficient to account for oceanic N2O depletion and the occurrence of regional sinks for atmospheric N2O.

Nitrous oxide production in two forested watersheds exhibiting symptoms of nitrogen saturation

1998 ◽  
Vol 28 (11) ◽  
pp. 1723-1732 ◽  
Author(s):  
William T Peterjohn ◽  
Richard J McGervey ◽  
Alan J Sexstone ◽  
Martin J Christ ◽  
Cassie J Foster ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Nitrogen Saturation ◽  
N Cycling ◽  
Woody Vegetation ◽  
N Saturation ◽  
Relative Importance ◽  
Forested Watersheds ◽  
Total N ◽  
Nitrous Oxide Production ◽  
Poorly Drained Soils

A major concern about N saturation is that it may increase the production of a strong greenhouse gas, nitrous oxide (N2O). We measured N2O production in two forested watersheds, a young, fertilized forest (WS 3) and an older, unfertilized forest (WS 4), to (i) assess the importance of N2O production in forests showing symptoms of N saturation; (ii) estimate the contribution of chemoautrophic nitrification to total N2O production; and (iii) examine the relative importance of factors that may control N2O production. During the study period, mean monthly rates of N2O production (3.41-11.42 µ N ·m-2·h-1) were consistent with measurements from other well-drained forest soils but were much lower than measurements from N-rich sites with poorly drained soils. Chemoautotrophic nitrification was important in both watersheds, accounting for 60% (WS 3) and 40% (WS 4) of total N2O production. In WS 3, N2O production was enhanced by additions of CaCO3 and may be constrained by low soil pH. In WS 4, N2O production on south-facing slopes was exceptionally low, constrained by low NO3 availability, and associated with a distinct assemblage of woody vegetation. From this observation, we hypothesize that differences in vegetation can influence N cycling rates and susceptibility to N saturation.

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