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Sample records for nitrous oxide n2o

  1. Nitrous oxide (N2O) emission from aquaculture: a review.

    PubMed

    Hu, Zhen; Lee, Jae Woo; Chandran, Kartik; Kim, Sungpyo; Khanal, Samir Kumar

    2012-06-19

    Nitrous oxide (N(2)O) is an important greenhouse gas (GHG) which has a global warming potential 310 times that of carbon dioxide (CO(2)) over a hundred year lifespan. N(2)O is generated during microbial nitrification and denitrification, which are common in aquaculture systems. To date, few studies have been conducted to quantify N(2)O emission from aquaculture. Additionally, very little is known with respect to the microbial pathways through which N(2)O is formed in aquaculture systems. This review suggests that aquaculture can be an important anthropogenic source of N(2)O emission. The global N(2)O-N emission from aquaculture in 2009 is estimated to be 9.30 × 10(10) g, and will increase to 3.83 × 10(11)g which could account for 5.72% of anthropogenic N(2)O-N emission by 2030 if the aquaculture industry continues to increase at the present annual growth rate (about 7.10%). The possible mechanisms and various factors affecting N(2)O production are summarized, and two possible methods to minimize N(2)O emission, namely aquaponic and biofloc technology aquaculture, are also discussed. The paper concludes with future research directions.

  2. Diurnality of soil nitrous oxide (N2O) emissions

    NASA Astrophysics Data System (ADS)

    Gelfand, I.; Moyer, R.; Poe, A.; Pan, D.; Abraha, M.; Chen, J.; Zondlo, M. A.; Robertson, P.

    2015-12-01

    Soil emissions of nitrous oxide (N2O) are important contributors to the greenhouse gas balance of the atmosphere. Agricultural soils contribute ~65% of anthropogenic N2O emissions. Understanding temporal and spatial variability of N2O emissions from agricultural soils is vital for closure of the global N2O budget and the development of mitigation opportunities. Recent studies have observed higher N2O fluxes during the day and lower at night. Understanding the mechanisms of such diurnality may have important consequences for our understanding of the N cycle. We tested the hypothesis that diurnal cycles are driven by root carbon exudes that stimulate denitrification and therefore N2O production. Alternatively, we considered that the cycle could result from higher afternoon temperatures that accelerate soil microbial activity. We removed all plants from a corn field plot and left another plot untouched. We measured soil N2O emissions in each plot using a standard static chamber technique throughout the corn growing season. And also compared static chamber results to ecosystem level N2O emissions as measured by eddy covariance tower equipped with an open-path N2O sensor. We also measured soil and air temperatures and soil water and inorganic N contents. Soil N2O emissions followed soil inorganic N concentrations and in control plot chambers ranged from 10 μg N m-2 hr-1 before fertilization to 13×103 after fertilization. We found strong diurnal cycles measured by both techniques with emissions low during night and morning hours and high during the afternoon. Corn removal had no effect on diurnality, but had a strong effect on the magnitude of soil N2O emissions. Soil temperature exhibited a weak correlation with soil N2O emissions and could not explain diurnal patterns. Further studies are underway to explore additional mechanisms that might contribute to this potentially important phenomena.

  3. Spatiotemporal variations of nitrous oxide (N 2 O) emissions from two reservoirs in SW China

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-Long; Liu, Cong-Qiang; Li, Si-Liang; Wang, Fu-Shun; Wang, Bao-Li; Wang, Zhong-Liang

    2011-10-01

    Greenhouse gas emissions from hydroelectric dams have recently given rise to controversies about whether hydropower still provides clean energy. China has a large number of dams used for energy supply and irrigation, but few studies have been carried out on aquatic nitrous oxide (N 2O) variation and its emissions in Chinese river-reservoir systems. In this study, N 2O spatiotemporal variations were investigated monthly in two reservoirs along the Wujiang River, Southwest China, and the emission fluxes of N 2O were estimated. N 2O production in the reservoirs tended to be dominated by nitrification, according to the correlation between N 2O and other parameters. N 2O saturation in the surface water of the Wujiangdu reservoir ranged from 214% to 662%, with an average fluctuation of 388%, while in the Hongjiadu reservoir, it ranged from 201% to 484%, with an average fluctuation of 312%. The dissolved N 2O in both reservoirs was over-saturated with respect to atmospheric equilibrium levels, suggesting that the reservoirs were net sources of N 2O emissions to the atmosphere. The averaged N 2O emission flux in the Wujiangdu reservoir was 0.64 μmol m -2 h -1, while it was 0.45 μmol m -2 h -1 in the Hongjiadu reservoir, indicating that these two reservoirs had moderate N 2O emission fluxes as compared to other lakes in the world. Downstream water of the dams had quite high levels of N 2O saturation, and the estimated annual N 2O emissions from hydropower generation were 3.60 × 10 5 and 2.15 × 10 5 mol N 2O for the Wujiangdu and the Hongjiadu reservoir, respectively. These fluxes were similar to the total N 2O emissions from the reservoir surfaces, suggesting that water released from reservoirs would be another important way for N 2O to diffuse into the atmosphere. It can be concluded that dam construction significantly changes the water environment, especially in terms of nutrient status and physicochemical conditions, which have obvious influences on the N 2O

  4. Effects of temperature on nitrous oxide (N2O) emission from intensive aquaculture system.

    PubMed

    Paudel, Shukra Raj; Choi, Ohkyung; Khanal, Samir Kumar; Chandran, Kartik; Kim, Sungpyo; Lee, Jae Woo

    2015-06-15

    This study examines the effects of temperature on nitrous oxide (N2O) emissions in a bench-scale intensive aquaculture system rearing Koi fish. The water temperature varied from 15 to 24 °C at interval of 3 °C. Both volumetric and specific rate for nitrification and denitrification declined as the temperature decreased. The concentrations of ammonia and nitrite, however, were lower than the inhibitory level for Koi fish regardless of temperature. The effects of temperature on N2O emissions were significant, with the emission rate and emission factor increasing from 1.11 to 1.82 mg N2O-N/d and 0.49 to 0.94 mg N2O-N/kg fish as the temperature decreased from 24 to 15 °C. A global map of N2O emission from aquaculture was established by using the N2O emission factor depending on temperature. This study demonstrates that N2O emission from aquaculture is strongly dependent on regional water temperatures as well as on fish production.

  5. Nitrous Oxide (N2O) Emissions by Termites: Does the Feeding Guild Matter?

    PubMed

    Brauman, Alain; Majeed, Muhammad Zeeshan; Buatois, Bruno; Robert, Alain; Pablo, Anne-Laure; Miambi, Edouard

    2015-01-01

    In the tropics, termites are major players in the mineralization of organic matter leading to the production of greenhouse gases including nitrous oxide (N2O). Termites have a wide trophic diversity and their N-metabolism depends on the feeding guild. This study assessed the extent to which N2O emission levels were determined by termite feeding guild and tested the hypothesis that termite species feeding on a diet rich in N emit higher levels of N2O than those feeding on a diet low in N. An in-vitro incubation approach was used to determine the levels of N2O production in 14 termite species belonging to different feeding guilds, collected from a wide range of biomes. Fungus-growing and soil-feeding termites emit N2O. The N2O production levels varied considerably, ranging from 13.14 to 117.62 ng N2O-N d(-1) (g dry wt.)(-1) for soil-feeding species, with Cubitermes spp. having the highest production levels, and from 39.61 to 65.61 ng N2O-N d(-1) (g dry wt.)(-1) for fungus-growing species. Wood-feeding termites were net N2O consumers rather than N2O producers with a consumption ranging from 16.09 to 45.22 ng N2O-N d(-1) (g dry wt.)(-1). Incubating live termites together with their mound increased the levels of N2O production by between 6 and 13 fold for soil-feeders, with the highest increase in Capritermes capricornis, and between 14 and 34 fold for fungus-growers, with the highest increase in Macrotermes muelleri. Ammonia-oxidizing (amoA-AOB and amoA-AOA) and denitrifying (nirK, nirS, nosZ) gene markers were detected in the guts of all termite species studied. No correlation was found between the abundance of these marker genes and the levels of N2O production from different feeding guilds. Overall, these results support the hypothesis that N2O production rates were higher in termites feeding on substrates with higher N content, such as soil and fungi, compared to those feeding on N-poor wood.

  6. Nitrous Oxide (N2O) Emissions by Termites: Does the Feeding Guild Matter?

    PubMed Central

    Buatois, Bruno; Robert, Alain; Pablo, Anne-Laure; Miambi, Edouard

    2015-01-01

    In the tropics, termites are major players in the mineralization of organic matter leading to the production of greenhouse gases including nitrous oxide (N2O). Termites have a wide trophic diversity and their N-metabolism depends on the feeding guild. This study assessed the extent to which N2O emission levels were determined by termite feeding guild and tested the hypothesis that termite species feeding on a diet rich in N emit higher levels of N2O than those feeding on a diet low in N. An in-vitro incubation approach was used to determine the levels of N2O production in 14 termite species belonging to different feeding guilds, collected from a wide range of biomes. Fungus-growing and soil-feeding termites emit N2O. The N2O production levels varied considerably, ranging from 13.14 to 117.62 ng N2O-N d-1 (g dry wt.)-1 for soil-feeding species, with Cubitermes spp. having the highest production levels, and from 39.61 to 65.61 ng N2O-N d-1 (g dry wt.)-1 for fungus-growing species. Wood-feeding termites were net N2O consumers rather than N2O producers with a consumption ranging from 16.09 to 45.22 ng N2O-N d-1 (g dry wt.)-1. Incubating live termites together with their mound increased the levels of N2O production by between 6 and 13 fold for soil-feeders, with the highest increase in Capritermes capricornis, and between 14 and 34 fold for fungus-growers, with the highest increase in Macrotermes muelleri. Ammonia-oxidizing (amoA-AOB and amoA-AOA) and denitrifying (nirK, nirS, nosZ) gene markers were detected in the guts of all termite species studied. No correlation was found between the abundance of these marker genes and the levels of N2O production from different feeding guilds. Overall, these results support the hypothesis that N2O production rates were higher in termites feeding on substrates with higher N content, such as soil and fungi, compared to those feeding on N-poor wood. PMID:26658648

  7. Tidal and spatial variability of nitrous oxide (N2O) in Sado estuary (Portugal)

    NASA Astrophysics Data System (ADS)

    Gonçalves, Célia; Brogueira, Maria José; Nogueira, Marta

    2015-12-01

    The estimate of the nitrous oxide (N2O) fluxes is fundamental to assess its impact on global warming. The tidal and spatial variability of N2O and the air-sea fluxes in the Sado estuary in July/August 2007 are examined. Measurements of N2O and other relevant environmental parameters (temperature, salinity, dissolved oxygen and dissolved inorganic nitrogen - nitrate plus nitrite and ammonium) were recorded during two diurnal tidal cycles performed in the Bay and Marateca region and along the estuary during ebb, at spring tide. N2O presented tidal and spatial variability and varied spatially from 5.0 nmol L-1 in Marateca region to 12.5 nmol L-1 in Sado river input. Although the Sado river may constitute a considerable N2O source to the estuary, the respective chemical signal discharge was rapidly lost in the main body of the estuary due to the low river flow during the sampling period. N2O varied with tide similarly between 5.2 nmol L-1 (Marateca) and 10.0 nmol L-1 (Sado Bay), with the maximum value reached two hours after flooding period. The influence of N2O enriched upwelled seawater (˜10.0 nmol L-1) was well visible in the estuary mouth and apparently represented an important contribution of N2O in the main body of Sado estuary. Despite the high water column oxygen saturation in most of Sado estuary, nitrification did not seem a relevant process for N2O production, probably as the concentration of the substrate, NH4+, was not adequate for this process to occur. Most of the estuary functioned as a N2O source, and only Marateca zone has acted as N2O sink. The N2O emission from Sado estuary was estimated to be 3.7 Mg N-N2O yr-1 (FC96) (4.4 Mg N-N2O yr-1, FRC01). These results have implications for future sampling and scaling strategies for estimating greenhouse gases (GHGs) fluxes in tidal ecosystems.

  8. Kinetics of nitrous oxide (N2O) formation and reduction by Paracoccus pantotrophus.

    PubMed

    Read-Daily, B L; Sabba, F; Pavissich, J P; Nerenberg, R

    2016-12-01

    Nitrous oxide (N2O) is a powerful greenhouse gas emitted from wastewater treatment, as well as natural systems, as a result of biological nitrification and denitrification. While denitrifying bacteria can be a significant source of N2O, they can also reduce N2O to N2. More information on the kinetics of N2O formation and reduction by denitrifying bacteria is needed to predict and quantify their impact on N2O emissions. In this study, kinetic parameters were determined for Paracoccus pantotrophus, a common denitrifying bacterium. Parameters included the maximum specific reduction rates, [Formula: see text], growth rates, [Formula: see text], and yields, Y, for reduction of NO3(-) (nitrate) to nitrite (NO2(-)), NO2(-) to N2O, and N2O to N2, with acetate as the electron donor. The [Formula: see text] values were 2.9 gN gCOD(-1) d(-1) for NO3(-) to NO2(-), 1.4 gN gCOD(-1) d(-1) for NO2(-) to N2O, and 5.3 gN gCOD(-1) d(-1) for N2O to N2. The [Formula: see text] values were 2.7, 0.93, and 1.5 d(-1), respectively. When N2O and NO3(-) were added concurrently, the apparent (extant) kinetics, [Formula: see text], assuming reduction to N2, were 6.3 gCOD gCOD(-1) d(-1), compared to 5.4 gCOD gCOD(-1) d(-1) for NO3(-) as the sole added acceptor. The [Formula: see text] was 1.6 d(-1), compared to 2.5 d(-1) for NO3(-) alone. These results suggest that NO3(-) and N2O were reduced concurrently. Based on this research, denitrifying bacteria like P. pantotrophus may serve as a significant sink for N2O. With careful design and operation, treatment plants can use denitrifying bacteria to minimize N2O emissions.

  9. Model testing for nitrous oxide (N2O) fluxes from Amazonian cattle pastures

    NASA Astrophysics Data System (ADS)

    Meurer, Katharina H. E.; Franko, Uwe; Spott, Oliver; Stange, C. Florian; Jungkunst, Hermann F.

    2016-10-01

    Process-oriented models have become important tools in terms of quantification of environmental changes, for filling measurement gaps, and building of future scenarios. It is especially important to couple model application directly with measurements for remote areas, such as Southern Amazonia, where direct measurements are difficult to perform continuously throughout the year. Processes and resulting matter fluxes may show combinations of steady and sudden reactions to external changes. The potent greenhouse gas nitrous oxide (N2O) is known for its sensitivity to e.g. precipitation events, resulting in intense but short-term peak events (hot moments). These peaks have to be captured for sound balancing. However, prediction of the effect of rainfall events on N2O peaks is not trivial, even for areas under distinct wet and dry seasons. In this study, we used process-oriented models in both a pre-and post-measurement manner in order to (a) determine important periods for N2O-N emissions under Amazonian conditions and (b) calibrate the models to Brazilian pastures based on measured data of environment conditions (soil moisture and Corg) and measured N2O-N fluxes. During the measurement period (early wet season), observed emissions from three cattle pastures did not react to precipitation events, as proposed by the models. Here both process understanding and models have to be improved by long-term data in high resolution in order to prove or disprove a lacking of N2O-N peaks. We strongly recommend the application of models as planning tools for field campaigns, but we still suggest model combinations and simultaneous usage.

  10. Quantification of nitrous oxide (N2O) emissions and soluble microbial product (SMP) production by a modified AOB-NOB-N2O-SMP model.

    PubMed

    Kim, MinJeong; Wu, Guangxue; Yoo, ChangKyoo

    2017-03-01

    A modified AOB-NOB-N2O-SMP model able to quantify nitrous oxide (N2O) emissions and soluble microbial product (SMP) production during wastewater treatment is proposed. The modified AOB-NOB-N2O-SMP model takes into account: (1) two-step nitrification by ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), (2) N2O production by AOB denitrification under oxygen-limited conditions and (3) SMP production by microbial growth and endogenous respiration. Validity of the modified model is demonstrated by comparing the simulation results with experimental data from lab-scale sequencing batch reactors (SBRs). To reliably implement the modified model, a model calibration that adjusts model parameters to fit the model outputs to the experimental data is conducted. The results of this study showed that the modeling accuracy of the modified AOB-NOB-N2O-SMP model increases by 19.7% (NH4), 51.0% (NO2), 57.8% (N2O) and 16.7% (SMP) compared to the conventional model which does not consider the two-step nitrification and SMP production by microbial endogenous respiration.

  11. Nitrous oxide (N2O) emissions from California based on 2010 CalNex airborne measurements

    NASA Astrophysics Data System (ADS)

    Xiang, Bin; Miller, Scot M.; Kort, Eric A.; Santoni, Gregory W.; Daube, Bruce C.; Commane, Roisin; Angevine, Wayne M.; Ryerson, Tom B.; Trainer, Michael K.; Andrews, Arlyn E.; Nehrkorn, Thomas; Tian, Hanqin; Wofsy, Steven C.

    2013-04-01

    Nitrous oxide (N2O) is an important gas for climate and for stratospheric chemistry, with a lifetime exceeding 100 years. Global concentrations have increased steadily since the 18th century, apparently due to human-associated emissions, principally from the application of nitrogen fertilizers. However, quantitative studies of agricultural emissions at large spatial scales are lacking, inhibited by the difficulty of measuring small enhancements in atmospheric concentration. Here we derive regional emission rates for N2O in the agricultural heartland of California based on analysis of in-situ airborne atmospheric observations collected using a new quantum cascade laser spectrometer. The data were obtained on board the NOAA WP-3 research aircraft during the CalNex (California Research at the Nexus of Air Quality and Climate Change) program in late spring 2010. We coupled the WRF (weather research and forecasting) model, a meso-scale meteorology model, with the STILT (stochastic time-inverted Lagrangian transport) model, a Lagrangian particle dispersion model, to link our in-situ airborne observations to surface emissions. We then used a variety of statistical methods to identify source areas and to optimize emission rates. Our results are consistent with the view that fertilizer application is the largest source of N2O in the Central Valley. The spatial distribution of surface emissions, based on California land use and activity maps, was very different than indicated in the leading emission inventory (EDGAR 4.0). Our estimated total emission flux of N2O for California in May and June was 3 - 4 times larger than the annual mean given for the state by EDGAR and other inventories, indicating a strong seasonal variation. We estimated the statewide total annual emissions of N2O to be 0.042 ± 0.011 Tg N/year, roughly equivalent to inventory values if we account for seasonal variations using observations obtained in the midwestern United States. This state total N2O

  12. Nitrous Oxide (N2O) Emissions from California based on 2010 CalNex Airborne Measurements

    NASA Astrophysics Data System (ADS)

    Xiang, B.; Miller, S.; Kort, E. A.; Santoni, G. W.; Daube, B.; Commane, R.; Angevine, W. M.; Ryerson, T. B.; Trainer, M.; Andrews, A. E.; Nehrkorn, T.; Tian, H.; Wofsy, S. C.

    2012-12-01

    Nitrous oxide (N2O) is an important gas for climate and for stratospheric chemistry, with an atmospheric lifetime exceeding 100 years. Global concentrations have increased steadily since the 18th century, apparently due to human-associated emissions, principally from application of nitrogen fertilizers. However, quantitative studies of agricultural emissions at large spatial scales are lacking, inhibited by the difficulty of measuring small enhancements of atmospheric concentrations. Here we derive regional emission rates for N2O in the Central Valley of California, based on analysis of in-situ airborne atmospheric observations collected using a quantum cascade laser spectrometer. The data were obtained on board the NOAA P-3 research aircraft during the CalNex (California Research at the Nexus of Air Quality and Climate Change) program in May and June, 2010. We coupled WRF (Weather Research and Forecasting) model to STILT (Stochastic Time-Inverted Lagrangian Transport) to link our in-situ observations to surface emissions, and then used a variety of statistical methods to identify source areas and to extract optimized emission rates from the inversion. Our results support the view that fertilizer application is the largest source of N2O in the Central Valley. But the spatial distribution of derived surface emissions, based on California land use and activity maps, was very different than indicated in the leading emissions inventory (EDGAR 4.0), and our estimated total emission flux of N2O for California during the study period was 3 - 4 times larger than EDGAR and other inventories.

  13. Nitrous Oxide (N2O) production in axenic Chlorella vulgaris microalgae cultures: evidence, putative pathways, and potential environmental impacts

    NASA Astrophysics Data System (ADS)

    Guieysse, B.; Plouviez, M.; Coilhac, M.; Cazali, L.

    2013-10-01

    Using antibiotic assays and genomic analysis, this study demonstrates nitrous oxide (N2O) is generated from axenic Chlorella vulgaris cultures. In batch assays, this production is magnified under conditions favouring intracellular nitrite accumulation, but repressed when nitrate reductase (NR) activity is inhibited. These observations suggest N2O formation in C. vulgaris might proceed via NR-mediated nitrite reduction into nitric oxide (NO) acting as N2O precursor via a pathway similar to N2O formation in bacterial denitrifiers, although NO reduction to N2O under oxia remains unproven in plant cells. Alternatively, NR may reduce nitrite to nitroxyl (HNO), the latter being known to dimerize to N2O under oxia. Regardless of the precursor considered, an NR-mediated nitrite reduction pathway provides a unifying explanation for correlations reported between N2O emissions from algae-based ecosystems and NR activity, nitrate concentration, nitrite concentration, and photosynthesis repression. Moreover, these results indicate microalgae-mediated N2O formation might significantly contribute to N2O emissions in algae-based ecosystems (e.g. 1.38-10.1 kg N2O-N ha-1 yr-1 in a 0.25 m deep raceway pond operated under Mediterranean climatic conditions). These findings have profound implications for the life cycle analysis of algae biotechnologies and our understanding of the global biogeochemical nitrogen cycle.

  14. Quantification of nitrous oxide (N2O) uptake in boreal forest soils by combining isotopic and microbial approaches

    NASA Astrophysics Data System (ADS)

    Welti, Nina; Siljanen, Henri; Biasi, Christina; Martikainen, Pertti

    2015-04-01

    The amount of nitrous oxide (N2O) produced during denitrification is highly regulated by the function of the last reductase enzyme (nitrous oxide reductase; nosZ) which is known to be inhibited by oxygen, low pH and low temperature, which are typical characteristics of boreal peatlands and some forest soils. Denitrification can be a sink for N2O, if the last step of the process is very efficient. Generally, the N2O sink potential of soils is poorly constrained; while uptake rates were often observed in field studies, the data was rejected as analytical errors or artifacts. This led to the question: when and by which mechanisms does N2O uptake occur in natural boreal forests? In order to answer this question, we established a 15N2O tracer experiment where the production of 15N2 and consumption of 15N2O were quantified in aerobic and anaerobic conditions followed by abundance analyses of genes and transcripts. The laboratory incubations were complemented with molecular approaches which linked the N2O dynamics with individual microbial species and transcriptomics. The abundance of denitrifying functional genes and gene transcripts reducing nitrous oxide (nosZ) were quantified throughout the experiment with sacrificial sampling in order to solve the role of typical and atypical denitrifying populations on N2O consumption. For this study, a Finnish boreal spruce forest and peatland were selected where previous field measurements have revealed negative N2O fluxes (i.e. N2O uptake). Soil horizons were selected in both the organic layer and uppermost mineral soil layer and in the peat layers 0-10 cm and 10-20 cm, where oxygen is limited and N2O uptake occurs at the field scale. 15N-N2O (99 AT %) was added to an initial N2O concentration of 1.7 ppm. All soils were flushed with 100% helium prior to the N2O addition to ensure that the NO3 stocks were reduced, leaving the added N2O as the sole activator of N2O uptake and primary N source. Aerobic N2O uptake was quantified in

  15. Nitrous oxide (N2O) production in axenic Chlorella vulgaris cultures: evidence, putative pathways, and potential environmental impacts

    NASA Astrophysics Data System (ADS)

    Guieysse, B.; Plouviez, M.; Coilhac, M.; Cazali, L.

    2013-06-01

    Using antibiotic assays and genomic analysis, this study demonstrates nitrous oxide (N2O) is generated from axenic C. vulgaris cultures. In batch assays, this production is magnified under conditions favoring intracellular nitrite accumulation, but repressed when nitrate reductase (NR) activity is inhibited. These observations suggest N2O formation in C. vulgaris might proceed via NR-mediated nitrite reduction into nitric oxide (NO) acting as N2O precursor via a pathway similar to N2O formation in bacterial denitrifiers, although NO reduction to N2O under oxia remains unproven in plant cells. Alternatively, NR may reduce nitrite to nitroxyl (HNO), the latter being known to dimerize to N2O under oxia. Regardless of the precursor considered, an NR-mediated nitrite reduction pathway provides a unifying explanation for correlations reported between N2O emissions from algae-based ecosystems and NR activity, nitrate concentration, nitrite concentration, and photosynthesis repression. Moreover, these results indicate microalgae-mediated N2O formation might significantly contribute to N2O emissions in algae-based ecosystems. These findings have profound implications for the life cycle analysis of algae biotechnologies and our understanding of the global biogeochemical nitrogen cycle.

  16. Nitrous oxide (N2O) fluxes from soils under different land use in Brazil

    NASA Astrophysics Data System (ADS)

    Meurer, Katharina H. E.; Madari, Beata E.; Franko, Uwe; Spott, Oliver; Stange, Claus F.; Jungkunst, Hermann F.

    2015-04-01

    Cropland area has been expanded in Brazil and by now the agricultural sector has been calculated as the major emitter of nitrous oxide (N2O). This state was preceded by the conversion of natural ecosystems, which inevitably causes changes in the carbon and nitrogen cycle of the soil. However, detailed model and measurement approaches are lacking for sound national estimates. Here we present data from model driven measurement campaigns from different ecosystems and the results of a review of available data on annual N2O fluxes. Contrary to expectations, emissions from agricultural land (1.13 kg N ha-1 yr-1) tended to be even lower than from rainforest (2.29 kg N ha-1 yr-1). At the same time, N-fertilization did not lead to a relevant increase in annual N2O emissions. Moreover, pastures showed an age-related decrease in emissions; median annual emissions from young pastures (≤ 10 years) were 2.52 kg N ha-1, whereas old pastures (> 10 years) emitted 0.90 kg N ha-1 yr-1. Since N2O is known to react very sensitive to changes (for example dry-wet changes, our measurement campaigns concentrated on the transitional period from dry to wet season, as predicted by our model simulations. For spatial explanation, model simulations were made for selected locations in the Brazilian state Mato Grosso, where agriculture is practiced since more than two decades. In accordance with the measurement and literature results, modelled emissions maize-soybean and cotton-soybean rotations were lower than from areas fallow areas. At the same time, the location and soil type, respectively, turned out to be an important factor when trying to quantify extensive emission budgets. Although existing models perform quite well based on monthly measurements, better adaptation is inevitable with regard to the possibility of more precise predictions. This requires spatial and temporal higher resolved monitoring, in order to involve soil types, which have so far not been considered sufficiently, and

  17. Controlling factors of nitrous oxide (N2O) emissions at the field-scale in an agricultural slope

    NASA Astrophysics Data System (ADS)

    Vilain, Guillaume; Garnier, Josette; Tallec, Gaëlle; Tournebize, Julien; Cellier, Pierre; Flipo, Nicolas

    2010-05-01

    Agricultural practices widely contribute to the atmospheric nitrous oxide (N2O) concentration increase and are the major source of N2O which account for 24% of the global annual emission (IPCC, 2007). Soil nitrification and denitrification are the microbial processes responsible for the production of N2O, which also depends on soil characteristics and management. Besides their control by various factors, such as climate, soil conditions and management (content of NO3- and NH4+, soil water content, presence of degradable organic material…), the role of topography is less known although it can play an important role on N2O emissions (Izaurralde et al., 2004). Due to the scarcity of data on N2O direct vs. indirect emission rate from agriculture in the Seine Basin (Garnier et al., 2009), one of the objectives of the study conducted here was to determine the N2O emission rates of the various land use representative for the Seine Basin, in order to better assess the direct N2O emissions, and to explore controlling factor such as meteorology, topography, soil properties and crop successions. The main objective of this study was at the same time to characterize N2O fluxes variability along a transect from an agricultural plateau to a river and to analyze the influence of landscape position on these emissions. We conducted this study in the Orgeval catchment (Seine basin, France; between 48°47' and 48°55' N, and 03°00' and 03°55' E) from May 2008 to August 2009 on two agricultural fields cropped with wheat, barley, oats, corn. N2O fluxes were monitored from weekly to bimonthly using static manual chambers placed along the chosen transect in five different landscape positions from the plateau to the River. This study has shown that soil moisture (expressed as Water Filled Pore Space) and NO3- soil concentrations explained most of the N2O flux variability during the sampling period. Most of N2O was emitted directly after N fertilization application during a relatively

  18. Global metaanalysis of the nonlinear response of soil nitrous oxide (N2O) emissions to fertilizer nitrogen.

    PubMed

    Shcherbak, Iurii; Millar, Neville; Robertson, G Philip

    2014-06-24

    Nitrous oxide (N2O) is a potent greenhouse gas (GHG) that also depletes stratospheric ozone. Nitrogen (N) fertilizer rate is the best single predictor of N2O emissions from agricultural soils, which are responsible for ∼ 50% of the total global anthropogenic flux, but it is a relatively imprecise estimator. Accumulating evidence suggests that the emission response to increasing N input is exponential rather than linear, as assumed by Intergovernmental Panel on Climate Change methodologies. We performed a metaanalysis to test the generalizability of this pattern. From 78 published studies (233 site-years) with at least three N-input levels, we calculated N2O emission factors (EFs) for each nonzero input level as a percentage of N input converted to N2O emissions. We found that the N2O response to N inputs grew significantly faster than linear for synthetic fertilizers and for most crop types. N-fixing crops had a higher rate of change in EF (ΔEF) than others. A higher ΔEF was also evident in soils with carbon >1.5% and soils with pH <7, and where fertilizer was applied only once annually. Our results suggest a general trend of exponentially increasing N2O emissions as N inputs increase to exceed crop needs. Use of this knowledge in GHG inventories should improve assessments of fertilizer-derived N2O emissions, help address disparities in the global N2O budget, and refine the accuracy of N2O mitigation protocols. In low-input systems typical of sub-Saharan Africa, for example, modest N additions will have little impact on estimated N2O emissions, whereas equivalent additions (or reductions) in excessively fertilized systems will have a disproportionately major impact.

  19. Global metaanalysis of the nonlinear response of soil nitrous oxide (N2O) emissions to fertilizer nitrogen

    PubMed Central

    Shcherbak, Iurii; Millar, Neville; Robertson, G. Philip

    2014-01-01

    Nitrous oxide (N2O) is a potent greenhouse gas (GHG) that also depletes stratospheric ozone. Nitrogen (N) fertilizer rate is the best single predictor of N2O emissions from agricultural soils, which are responsible for ∼50% of the total global anthropogenic flux, but it is a relatively imprecise estimator. Accumulating evidence suggests that the emission response to increasing N input is exponential rather than linear, as assumed by Intergovernmental Panel on Climate Change methodologies. We performed a metaanalysis to test the generalizability of this pattern. From 78 published studies (233 site-years) with at least three N-input levels, we calculated N2O emission factors (EFs) for each nonzero input level as a percentage of N input converted to N2O emissions. We found that the N2O response to N inputs grew significantly faster than linear for synthetic fertilizers and for most crop types. N-fixing crops had a higher rate of change in EF (ΔEF) than others. A higher ΔEF was also evident in soils with carbon >1.5% and soils with pH <7, and where fertilizer was applied only once annually. Our results suggest a general trend of exponentially increasing N2O emissions as N inputs increase to exceed crop needs. Use of this knowledge in GHG inventories should improve assessments of fertilizer-derived N2O emissions, help address disparities in the global N2O budget, and refine the accuracy of N2O mitigation protocols. In low-input systems typical of sub-Saharan Africa, for example, modest N additions will have little impact on estimated N2O emissions, whereas equivalent additions (or reductions) in excessively fertilized systems will have a disproportionately major impact. PMID:24927583

  20. Nitrous Oxide (N2O) Production and Consumption after the Rewetting of Soils in Isolated Wetlands and Surrounding Pasture Upland

    NASA Astrophysics Data System (ADS)

    Hu, J.; Inglett, K.; Inglett, P.; Clark, M.; Reddy, R.

    2012-12-01

    Nitrous oxide (N2O) is one of the most potent greenhouse gases and the highest N2O emissions from pasture lands are always found after the rewetting of soils which is caused by events, such as rainfall and irrigation. The N2O emission peaks are attributed to denitrification because of the anaerobic condition in the soil created by rewetting and the accumulated substrates (nitrate and labile organic carbon) during the drying period. Therefore, the N2O emissions after rewetting represent the difference between N2O production and N2O consumption by denitrification. Isolated wetlands, which have no surface water connectivity with nearby water bodies, are common feature in many pasture ecosystems. They act as water and nutrient storage systems at landscape scale and have distinct biogeochemical features with the surrounding pasture uplands. An isolated wetland located in cow-grazing pasture was selected as our study site. Study area has been stratified into three zones according to the vegetative communities and basin morphology: wetland center zone (Center), transient edge zone (Edge) and pasture upland zone (Upland). Six transects extended from the center of wetland to surrounding pasture upland have been set up, in which 3 transects have been fenced aiming for excluding the cow and calf grazing. Soil samples (0-10 cm) were collected in each zone along each transects. Soil biogeochemical properties were characterized on soil subsamples. A laboratory incubation study was performed to quantify N2O production and consumption rates of the rewetted soils. Our results indicated that the N2O production process normally had a biphasic pattern, with a low production rates in 6 h after rewetting, followed by a faster production rate between 6 h to the time when accumulated N2O began to be consumed. In the first 6 h after rewetting, soils from Edge had the highest production rates because of the relative higher nitrate content. Nitrous oxide production rates were significantly

  1. Mitigation of nitrous oxide (N2 O) emission from swine wastewater treatment in an aerobic bioreactor packed with carbon fibers.

    PubMed

    Yamashita, Takahiro; Yamamoto-Ikemoto, Ryoko; Yokoyama, Hiroshi; Kawahara, Hirofumi; Ogino, Akifumi; Osada, Takashi

    2015-03-01

    Mitigation of nitrous oxide (N2 O) emission from swine wastewater treatment was demonstrated in an aerobic bioreactor packed with carbon fibers (CF reactor). The CF reactor had a demonstrated advantage in mitigating N2 O emission and avoiding NOx (NO3  + NO2 ) accumulation. The N2 O emission factor was 0.0003 g N2 O-N/gTN-load in the CF bioreactor compared to 0.03 gN2 O-N/gTN-load in an activated sludge reactor (AS reactor). N2 O and CH4 emissions from the CF reactor were 42 g-CO2 eq/m(3) /day, while those from the AS reactor were 725 g-CO2 eq/m(3) /day. The dissolved inorganic nitrogen (DIN) in the CF reactor removed an average of 156 mg/L of the NH4 -N, and accumulated an average of 14 mg/L of the NO3 -N. In contrast, the DIN in the AS reactor removed an average 144 mg/L of the NH4 -N and accumulated an average 183 mg/L of the NO3 -N. NO2 -N was almost undetectable in both reactors.

  2. 40 CFR Table Jj-7 to Subpart Jj of... - Nitrous Oxide Emission Factors (kg N2O-N/kg Kjdl N)

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Nitrous Oxide Emission Factors (kg N2O-N/kg Kjdl N) JJ Table JJ-7 to Subpart JJ of Part 98 Protection of Environment ENVIRONMENTAL... Pt. 98, Subpt. JJ, Table JJ-7 Table JJ-7 to Subpart JJ of Part 98—Nitrous Oxide Emission Factors...

  3. N2O binding at a [4Cu:2S] copper-sulphur cluster in nitrous oxide reductase.

    PubMed

    Pomowski, Anja; Zumft, Walter G; Kroneck, Peter M H; Einsle, Oliver

    2011-08-14

    Nitrous oxide (N(2)O) is generated by natural and anthropogenic processes and has a critical role in environmental chemistry. It has an ozone-depleting potential similar to that of hydrochlorofluorocarbons as well as a global warming potential exceeding that of CO(2) 300-fold. In bacterial denitrification, N(2)O is reduced to N(2) by the copper-dependent nitrous oxide reductase (N(2)OR). This enzyme carries the mixed-valent Cu(A) centre and the unique, tetranuclear Cu(Z) site. Previous structural data were obtained with enzyme isolated in the presence of air that is catalytically inactive without prior reduction. Its Cu(Z) site was described as a [4Cu:S] centre, and the substrate-binding mode and reduction mechanism remained elusive. Here we report the structure of purple N(2)OR from Pseudomonas stutzeri, handled under the exclusion of dioxygen, and locate the substrate in N(2)O-pressurized crystals. The active Cu(Z) cluster contains two sulphur atoms, yielding a [4Cu:2S] stoichiometry; and N(2)O bound side-on at Cu(Z), in close proximity to Cu(A). With the substrate located between the two clusters, electrons are transferred directly from Cu(A) to N(2)O, which is activated by side-on binding in a specific binding pocket on the face of the [4Cu:2S] centre. These results reconcile a multitude of available biochemical data on N(2)OR that could not be explained by earlier structures, and outline a mechanistic pathway in which both metal centres and the intervening protein act in concert to achieve catalysis. This structure represents the first direct observation, to our knowledge, of N(2)O bound to its reductase, and sheds light on the functionality of metalloenzymes that activate inert small-molecule substrates. The principle of using distinct clusters for substrate activation and for reduction may be relevant for similar systems, in particular nitrogen-fixing nitrogenase.

  4. Direct nitrous oxide (N2O) fluxes from soils under different land use in Brazil—a critical review

    NASA Astrophysics Data System (ADS)

    Meurer, Katharina H. E.; Franko, Uwe; Stange, Claus F.; Dalla Rosa, Jaqueline; Madari, Beata E.; Jungkunst, Hermann F.

    2016-02-01

    Brazil typifies the land use changes happening in South America, where natural vegetation is continuously converted into agriculturally used lands, such as cattle pastures and croplands. Such changes in land use are always associated with changes in the soil nutrient cycles and result in altered greenhouse gas fluxes from the soil to the atmosphere. In this study, we analyzed literature values to extract patterns of direct nitrous oxide (N2O) emissions from soils of different ecosystems in Brazil. Fluxes from natural ecosystems exhibited a wide range: whereas median annual flux rates were highest in Amazonian and Atlantic rainforests (2.42 and 0.88 kg N ha-1), emissions from cerrado soils were close to zero. The decrease in emissions from pastures with increasing time after conversion was associated with pasture degradation. We found comparatively low N2O-N fluxes from croplands (-0.07 to 4.26 kg N ha-1 yr-1 , median 0.80 kg N ha-1 yr-1) and a low response to N fertilization. Contrary to the assumptions, soil parameters, such as pH, Corg, and clay content emerged as poor predictors for N2O fluxes. This could be a result of the formation of micro-aggregates, which strongly affect the hydraulic properties of the soil, and consequently define nitrification and denitrification potentials. Since data from croplands mainly derived from areas that had been under natural cerrado vegetation before, it could explain the low emissions under agriculture. Measurements must be more frequent and regionally spread in order to enable sound national estimates.

  5. Nitrous oxide (N2O) fluxes from soils under different land use in Brazil - Overview, measurements, and modeling

    NASA Astrophysics Data System (ADS)

    Meurer, K. H. E.; Franko, U.; Spott, O.; Stange, C. F.; Jungkunst, H. F.

    2014-12-01

    Cropland area has been expanded in Brazil and by now the agricultural sector has been calculated as the major emitter of nitrous oxide (N2O). This state was preceded by the conversion of natural ecosystems, which inevitably causes changes in the carbon and nitrogen cycle of the soil. However, detailed model and measurement approaches are lacking for sound national estimates. Here we present data from model driven measurement campaigns from different ecosystems and the results of a review of available data on annual N2O fluxes throughout Brazil. Contrary to expectations, emissions from agricultural land (0.80 kg N ha-1 yr-1) tended to be lower than from rainforest (2.29 kg N ha-1­­ yr-1). At the same time, N-fertilization did not lead to a relevant increase in annual N­­2O emissions. Moreover, pastures showed an age-related decrease in emissions: median annual emissions from young pastures (≤ 10 years) were 2.52 kg N ha-1, whereas old pastures (> 10 years) emitted 0.90 kg N ha-1 yr-1. Since N2O is known to react very sensitively to changes (for example dry-wet changes), it is likely that high emissions occur during actual land conversions. Consequently, our own measurement campaigns concentrated on the transitional period from dry to wet season, as already predicted by previously performed model simulations. Results from these short-term measurements supported the findings of the review, regarding land use-specific differences in N2O-N fluxes, but did not support our assumptions of emission pulses after rewetting of the soil. Applied process-oriented models performed quite well on the studied sites, but better adaptation is inevitable with regard to the possibility of more precise predictions and spatial extrapolation. This requires spatial and temporal higher resolved monitoring, in order to involve soil types, which have so far not been considered sufficiently, and capture short-term effects from precipitation and fertilizer events.

  6. Nitrous oxide (N2O) fluxes from soils under different land use in Brazil - Overview, measurements, and modeling

    NASA Astrophysics Data System (ADS)

    Meurer, K. H. E.; Franko, U.; Spott, O.; Stange, C. F.; Jungkunst, H. F.

    2015-12-01

    Cropland area has been expanded in Brazil and by now the agricultural sector has been calculated as the major emitter of nitrous oxide (N2O). This state was preceded by the conversion of natural ecosystems, which inevitably causes changes in the carbon and nitrogen cycle of the soil. However, detailed model and measurement approaches are lacking for sound national estimates. Here we present data from model driven measurement campaigns from different ecosystems and the results of a review of available data on annual N2O fluxes throughout Brazil. Contrary to expectations, emissions from agricultural land (0.80 kg N ha-1 yr-1) tended to be lower than from rainforest (2.29 kg N ha-1­­ yr-1). At the same time, N-fertilization did not lead to a relevant increase in annual N­­2O emissions. Moreover, pastures showed an age-related decrease in emissions: median annual emissions from young pastures (≤ 10 years) were 2.52 kg N ha-1, whereas old pastures (> 10 years) emitted 0.90 kg N ha-1 yr-1. Since N2O is known to react very sensitively to changes (for example dry-wet changes), it is likely that high emissions occur during actual land conversions. Consequently, our own measurement campaigns concentrated on the transitional period from dry to wet season, as already predicted by previously performed model simulations. Results from these short-term measurements supported the findings of the review, regarding land use-specific differences in N2O-N fluxes, but did not support our assumptions of emission pulses after rewetting of the soil. Applied process-oriented models performed quite well on the studied sites, but better adaptation is inevitable with regard to the possibility of more precise predictions and spatial extrapolation. This requires spatial and temporal higher resolved monitoring, in order to involve soil types, which have so far not been considered sufficiently, and capture short-term effects from precipitation and fertilizer events.

  7. Physiological and Genotypic Characteristics of Nitrous Oxide (N2O)-Emitting Pseudomonas Species Isolated from Dent Corn Andisol Farmland in Hokkaido, Japan

    PubMed Central

    Nie, Yanxia; Li, Li; Isoda, Reika; Wang, Mengcen; Hatano, Ryusuke; Hashidoko, Yasuyuki

    2016-01-01

    Dent corn Andisol at the Hokkaido University Shizunai Livestock Experimental Farm actively emits nitrous oxide (N2O). In order to screen for culturable and active N2O emitters with high N2O emission potential, soft gel medium containing excess KNO3 was inoculated with soil suspensions from farm soil samples collected at different land managements. Dominant bacterial colonies were searched for among 20 of the actively N2O-emitting cultures from post-harvest soil and 19 from pre-tilled soil, and all isolates were subjected to the culture-based N2O emission assay. Ten active N2O-emitting bacteria, four from post-harvest soil and six from pre-tilled soil, out of 156 isolates were identified as genus Pseudomonas by 16S rRNA gene sequencing. These N2O emitters showed clear responses to NO3− within a neutral pH range (5.5–6.7), and accelerated N2O production with 1.5–15 mM sucrose supplementation, suggesting the production of N2O during the denitrification process. However, the negative responses of 6 active N2O emitters, 3 from post-harvest soil and 3 from pre-tilled soil, out of the 10 isolates in the acetylene-blocking assay suggest that these 6 N2O emitters are incomplete denitrifiers that have lost their N2O reductase (N2OR) activity. Although the PCR assay for the denitrification-associated genes, narG and nirK/S, was positive in all 10 Pseudomonas isolates, those negative in the acetylene-blocking assay were nosZ-negative. Therefore, these results imply that the high N2O emission potential of dent corn Andisol is partly attributed to saprophytic, nosZ gene-missing pseudomonad denitrifiers. PMID:27109825

  8. High-resolution measurement of nitrous oxide in the Elbe estuary under hypoxia: Hot-spots of biological N2O production

    NASA Astrophysics Data System (ADS)

    Brase, Lisa; Lendt, Ralf; Sanders, Tina; Dähnke, Kirstin

    2016-04-01

    Nitrous oxide (N2O) is one of the most important greenhouse gases. Its global warming potential exceeds that of CO2 by a factor of ˜300. Estuaries, being sites of intense biological N-turnover, are one of the major natural sources of N2O emissions. On two ship cruises in April and June 2015, concentrations of N2O were measured in the surface water using equilibrator laser based on-line measurements. Based on these high-resolution N2O profiles along the Elbe estuary, N2O saturation and N2O-fluxes between surface water and air were calculated. Additionally, DIN concentrations and dual stable isotopes of nitrate (δ15N and δ18O) were analyzed. Concentration and water-to-air fluxes of N2O were highest in the Hamburg port region and dropped quickly further downstream. Highest water-to-air fluxes were up to 800μM/m2/d and 1600μM/m2/d in April and in June, respectively. Downstream of the port region, an N2O oversaturation of 150-200% was estimated over the entire estuary, with saturation approaching equilibrium (96-100%) only in the North Sea region. N2O production was much higher in June than in April 2015, likely coupled to lower oxygen saturation in the water column in June. Based on these measurements, the port of Hamburg region was identified as a hot-spot of N2O production. High N2O concentration and depleted values of nitrate isotopes suggest that nitrification is a significant source of N2O in the estuary, especially at low oxygen concentration. In the Elbe estuary, hypoxia obviously drastically increased the emissions of the greenhouse gas N2O.

  9. Assessment of nitric oxide (NO) redox reactions contribution to nitrous oxide (N2 O) formation during nitrification using a multispecies metabolic network model.

    PubMed

    Perez-Garcia, Octavio; Chandran, Kartik; Villas-Boas, Silas G; Singhal, Naresh

    2016-05-01

    Over the coming decades nitrous oxide (N2O) is expected to become a dominant greenhouse gas and atmospheric ozone depleting substance. In wastewater treatment systems, N2O is majorly produced by nitrifying microbes through biochemical reduction of nitrite (NO2(-)) and nitric oxide (NO). However it is unknown if the amount of N2O formed is affected by alternative NO redox reactions catalyzed by oxidative nitrite oxidoreductase (NirK), cytochromes (i.e., P460 [CytP460] and 554 [Cyt554 ]) and flavohemoglobins (Hmp) in ammonia- and nitrite-oxidizing bacteria (AOB and NOB, respectively). In this study, a mathematical model is developed to assess how N2O formation is affected by such alternative nitrogen redox transformations. The developed multispecies metabolic network model captures the nitrogen respiratory pathways inferred from genomes of eight AOB and NOB species. The performance of model variants, obtained as different combinations of active NO redox reactions, was assessed against nine experimental datasets for nitrifying cultures producing N2O at different concentration of electron donor and acceptor. Model predicted metabolic fluxes show that only variants that included NO oxidation to NO2(-) by CytP460 and Hmp in AOB gave statistically similar estimates to observed production rates of N2O, NO, NO2(-) and nitrate (NO3(-)), together with fractions of AOB and NOB species in biomass. Simulations showed that NO oxidation to NO2(-) decreased N2O formation by 60% without changing culture's NO2(-) production rate. Model variants including NO reduction to N2O by Cyt554 and cNor in NOB did not improve the accuracy of experimental datasets estimates, suggesting null N2O production by NOB during nitrification. Finally, the analysis shows that in nitrifying cultures transitioning from dissolved oxygen levels above 3.8 ± 0.38 to <1.5 ± 0.8 mg/L, NOB cells can oxidize the NO produced by AOB through reactions catalyzed by oxidative NirK.

  10. Carbon dioxide(CO2) and nitrous oxide (N2O) fluxes in an agro-ecosystems under changing physical and biological conditions

    NASA Astrophysics Data System (ADS)

    Liang, L.; Eberwein, J.; Oikawa, P.; Jenerette, D.; Grantz, D. A.

    2013-12-01

    Liyin Liang1, Jennifer Eberwein1, Patty Oikawa1, Darrel Jenerette1, David Grantz1 1Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA Carbon dioxide (CO2) and nitrous oxide (N2O) are the major greenhouse gases and together produce a strong positive radiative forcing in the atmosphere. The fluxes of CO2 and N2O from soil to atmosphere vary with physical and biological factors, e.g., temperature, soil moisture, pH value, soil organic carbon contents, microorganism communities and so on. Understanding the interactions among these factors is critical to estimation of CO2 and N2O emissions. We investigate these fluxes in an extreme production environment with very high maximum temperatures, at the agricultural experiment station of University of California-Desert Research Center in the Imperial Valley of southern California. In this research, we measured the CO2 and N2O fluxes from soil incubation under controlled laboratory conditions, in surface chambers under field conditions and by eddy covariance. We explore the variation of CO2 and N2O fluxes and relationship between them in this extreme biofuel production environment. The discrete chamber measurements showed that the N2O flux in our field sites is 2.39×0.70 μg N m-2 hr-1, with a 95% confidence interval (CI) from 0.86 to 3.92 μg N m-2 hr-1. Compared to the previous reported value (0.45~26.26 μg N m-2 hr-1) of N2O flux in California, the N2O flux from biofuel crop land is in the lower level, although more observations should be took to confirm it. The N2O flux also shows very high variability within a field of biomass Sorghum, ranging from 0.40 to 8.19 μg N m-2 hr-1 across 11 sites owning to the high variability of physical and biological factors. Soil incubation measurements will be conducted to identify the sources of this variability. The eddy covariance measurements will allow calculation of the CO2 and N2O emissions at the ecosystem level as a step in quantifying

  11. Characterizing Nitrous Oxide (N2O) Emissions over a Wheat-based Cropping System in the Northwest United States Using the Modified Bowen Ratio Technique and Static Chambers

    NASA Astrophysics Data System (ADS)

    Waldo, Sarah; Kostyanovsky, Kirill; O'Keeffe, Patrick; Pressley, Shelley; Huggins, Dave; Stockle, Claudio; Lamb, Brian

    2015-04-01

    Nitrous oxide (N2O) is a potent greenhouse gas and ozone depleting substance. Agricultural soils are the primary source of N2O, which is created as a by-product of soil microbial processes. The production and emission of N2O is characterized by high spatial and temporal variability, or "hot spots" and "hot moments". These behaviors, along with limitations in instrument sensitivity to N2O, are challenges in characterizing emissions. Many studies have monitored N2O emissions using either static chambers or micrometeorological measurements or the two methods together. The two techniques are complementary: chamber methods have a lower detection limit and are more reliable as their operation does not depend on atmospheric conditions, but may not capture spatial variability even with multiple chambers. Tower-based methods are subject to relatively high data loss due to non-ideal conditions and to less sensitive detection limits, but have a larger measurement footprint and can characterize field-scale emissions. This study aims to characterize a long-term, field-scale N2O budget over two winter wheat fields located in the Inland Pacific Northwest of the United States, both in terms of an annual emission budget and in terms of understanding what causes hot moments. We combined continuous measurements of N2O emissions from a system of sixteen automated, static chambers with tower-based measurements of N2O fluxes. We used the modified Bowen ratio (MBR) technique with temperature as a tracer. Preliminary results indicate that freeze-thaw cycles in the winter make up a higher percentage of annual emissions than previously thought. Furthermore, comparison of the chamber results to the tower-based measurements imply that the chambers may be underestimating field-scale N2O fluxes because they are not adequately capturing hot spots of emissions. We are conducting ongoing work on how to integrate the two measurement techniques, as well as how the empirical measurements compare with

  12. Factors Controlling Fluxes of Nitrous Oxide (N-N2O) in AN Upland Tropical Forest (atlantic Forest) - Brazil, Rio de Janeiro

    NASA Astrophysics Data System (ADS)

    Perry, I.; de Mello, W. Z.; McDowell, W. H.

    2010-12-01

    Atlantic Forest is located along the Brazilian coast and inland to Paraguay and Argentina. It has been largely devastated years ago by anthropogenic activities, such as agriculture and urbanization. Only ten percent of its original area remains (100.000 km2), which is concentrated on high lands. Atlantic Forest is a biodiversity hotspot that receives high nitrogen (N) input through atmospheric deposition in forests of Rio de Janeiro; however, not much is known about the consequences of this N addition. This study has been conducted in the Serra dos Orgaos National Park (SONP - 22.782 km2) located a few kilometers Northeast of Rio de Janeiro Metropolitan Region, Sea Mountain. The forest, characterized as Tropical Moist Forest, is rigorously protected. Vegetation varies along the altitudinal gradient, where the highest peak is at 2,200m asl. Previous studies reported that N atmospheric deposition in SONP varies from 14 to 24 kg ha-1 year-1. The high N deposition on tropical forests increases emission to the atmosphere of N-N2O, a greenhouse gas. There is a lack of N-N2O measurements in tropical forests, mainly in upland tropical forests. We present fluxes of N-N2O from a Brazilian upland tropical forest, and assess the factors controlling N-N2O fluxes. Samples were collected from eight grids (48m2), between 330-451m asl (Subtropical vegetation) and eight grids between 1137-1251m (Montane vegetation), during the dry (July 2008) and wet (Jan-Feb 2009) seasons. Daily, N-N2O (N=372) and soil (N=185) were collected. Nitrous oxide emission was 0,7 (lower altitude) and 0,3 kgN ha-1 year-1 (higher altitude), which is lower than in other upland tropical forests, such as Luquillo Experimental Forest, Puerto Rico, where atmospheric N input (4 kg ha-1 year-1) is not as high as in SONP. Water filled pore space, soil temperature, phosphorus and C:N are the main factors controlling N-N2O fluxes. Manganese was not a good indicator for presence or absence of N-N2O. Higher N-N2O

  13. Free nitrous acid and pH determine the predominant ammonia-oxidizing bacteria and amount of N2O in a partial nitrifying reactor.

    PubMed

    Kinh, Co Thi; Ahn, Johwan; Suenaga, Toshikazu; Sittivorakulpong, Nakanya; Noophan, Pongsak; Hori, Tomoyuki; Riya, Shohei; Hosomi, Masaaki; Terada, Akihiko

    2017-02-01

    We investigated the effects of free ammonia (FA) and free nitrous acid (FNA) concentrations on the predominant ammonia-oxidizing bacteria (AOB) and the emission of nitrous oxide (N2O) in a lab-scale sequencing batch reactor for partial nitrification. The reactor was operated with stepwise increases in the NH4(+) loading rate, which resulted in a maximum FA concentration of 29.3 mg-N/L at pH 8.3. Afterwards, FNA was increased by a gradual decrease of pH, reaching its maximum concentration of 4.1 mg-N/L at pH 6.3. Fluorescence in situ hybridization indicated that AOB remained predominant during the operation, achieving specific nitrification rates of 1.04 and 0.99 g-N/g-VSS/day at the highest accumulations of FA and FNA, respectively. These rates were in conjunction with partial nitrification efficiencies of >84%. The N2O emission factor of oxidized NH4(+) was 0.90% at pH 7.0, which was higher than those at pH 8.3 (0.11%) and 6.3 (0.12%), the pHs with the maximum FA and FNA concentrations, respectively. High-throughput sequencing of 16S ribosomal RNA genes showed that increases in FNA drastically changed the predominant AOB species, although increased FA produced no significant changes. This study demonstrates that the FNA concentration and pH are the main drivers that determine the predominant AOB species and N2O-emission in a partial nitrifying bioreactor.

  14. UV Absorption Cross Sections of Nitrous Oxide (N2O) and Carbon Tetrachloride (CCl4) Between 210 and 350 K and the Atmospheric Implications

    NASA Technical Reports Server (NTRS)

    Carlon, Nabilah Rontu; Papanastasiou, Dimitrios K.; Fleming, Eric L.; Jackman, Charles H.; Newman, Paul A.; Burkholder, James B.

    2010-01-01

    Absorption cross sections of nitrous oxide (N2O) and carbon tetrachloride (CCl4) are reported at five atomic UV lines (184.95, 202.548, 206.200, 213.857, and 228.8 nm) at 27 temperatures in the range 210-350 K. In addition, UV absorption spectra of CCl4 are reported between 200-235 nm as a function of temperature (225-350 K). The results from this work are critically compared with results from earlier studies. For N2O, the present results are in good agreement with the current JPL recommendation enabling a reduction in the estimated uncertainty in the N2O atmospheric photolysis rate. For CCl4, the present cross section results are systematically greater than the current recommendation at the reduced temperatures most relevant to stratospheric photolysis. The new cross sections result in a 5-7% increase in the modeled CCl4 photolysis loss, and a slight decrease in the stratospheric lifetime, from 51 to 50 years, for present day conditions. The corresponding changes in modeled inorganic chlorine and ozone in the stratosphere are quite small. A CCl4 cross section parameterization for use in 37 atmospheric model calculations is presented.

  15. The Great Cormorant (Phalacrocorax carbo) colony as a "hot spot" of nitrous oxide (N2O) emission in central Japan

    NASA Astrophysics Data System (ADS)

    Mizota, Chitoshi; Noborio, Kosuke; Mori, Yoshiaki

    2012-09-01

    Unusual high soil fluxes up to ca. 500 mg N2O m-2 h-1 emission were associated with a continued breeding/roosting colony of Great Cormorant in central Japan. This flux is nearly two-orders of magnitude higher than those hitherto documented. The flux was markedly dependent upon the soil surface temperature, i.e., higher in April-October during the prevailing high air temperatures, as compared with November to March. Integrated input of fecal N at rearing and fledging stages of chicks followed by coupled mineralization, nitrification and subsequently denitrification processes under humid and temperate regimes is responsible for such an unusual flux. The Great Cormorant colony serves as a "hot spot" of N2O emission of natural origin.

  16. High production of nitrous oxide (N2O), methane (CH4) and dimethylsulphoniopropionate (DMSP) in a massive marine phytoplankton culture

    NASA Astrophysics Data System (ADS)

    Florez-Leiva, L.; Tarifeño, E.; Cornejo, M.; Kiene, R.; Farías, L.

    2010-09-01

    The production of large amounts of algal biomass for different purposes such as aquaculture or biofuels, may cause impacts on the marine environment. One such impact is the production of radiatively active trace gases and aerosols with climate cooling (dimethyl sulfide DMS and its precursor DMSP) and warming (N2O and CH4) effects. Total and dissolved DMSP, N2O and CH4, together with other environmental variables were monitored daily for 46 days within a massive microalgae monoculture of Nannochloris (Chlorophyceae) in an open pond system. The growth of this green microalgae was stimulated by the addition of N- and P-rich salts, resulting in exponential growth (growth phase) during the first 17 days observed by cell abundance (1 × 106 to 4.4 × 106 cell mL-1) and Chl-a levels (from 1.4 to 96 mg Chl-a m-3) followed by a decrease in both Chl-a and cell abundance (senescence phase). Total DMSP (from 6.3 to 142 μmol m-3), dissolved DMSP i.e. 5.8 to 137 μmol m-3 and N2O (from 8 to 600 μmol m-3) abruptly peaked during the senescence phase, whereas CH4 steadily increased between 2 and 10 μmol m-3 during the growth phase. Different ratios between tracers and Chl-a during both phases reveal different biochemical processes involved in the cycling of these gases and tracers. Our results show that despite the consumption of large quantities of CO2 by the massive algal culture, a minor amount of DMS and huge amounts of greenhouse gases were produced, in particular N2O, which has a greater radiative effect per molecule than CO2. These findings have important implications for biogeochemical studies and for environmental management of aquaculture activities.

  17. Validation of an analytical method for nitrous oxide (N2O) laughing gas by headspace gas chromatography coupled to mass spectrometry (HS-GC-MS): forensic application to a lethal intoxication.

    PubMed

    Giuliani, N; Beyer, J; Augsburger, M; Varlet, V

    2015-03-01

    Drug abuse is a widespread problem affecting both teenagers and adults. Nitrous oxide is becoming increasingly popular as an inhalation drug, causing harmful neurological and hematological effects. Some gas chromatography-mass spectrometry (GC-MS) methods for nitrous oxide measurement have been previously described. The main drawbacks of these methods include a lack of sensitivity for forensic applications; including an inability to quantitatively determine the concentration of gas present. The following study provides a validated method using HS-GC-MS which incorporates hydrogen sulfide as a suitable internal standard allowing the quantification of nitrous oxide. Upon analysis, sample and internal standard have similar retention times and are eluted quickly from the molecular sieve 5Å PLOT capillary column and the Porabond Q column therefore providing rapid data collection whilst preserving well defined peaks. After validation, the method has been applied to a real case of N2O intoxication indicating concentrations in a mono-intoxication.

  18. Simultaneous determination of stable isotopic compositions of nitrous oxide (δ15N and δ18O of N2O) and methane (δ13C of CH4) in nanomolar quantities from a single water sample

    NASA Astrophysics Data System (ADS)

    Hirota, A.; Tsunogai, U.; Komatsu, D. D.; Nakagawa, F.

    2010-12-01

    The stable isotopic compositions of nitrous oxide (δ15N of N2O and δ18O of N2O, respectively) and methane (δ13C of CH4) have provided us with some interesting geochemical insights. We have developed a rapid, sensitive, and automated analytical system to simultaneously determine the concentrations and stable isotopic compositions of nanomolar quantities of N2O and CH4 in the environmental water, by combining continuous-flow isotope-ratio mass spectrometry and a He-sparging system to extract and purify the dissolved gases. Our system, which is composed of a sparging bottle, a chemical trap, four cold traps and a capillary gas chromatograph that use ultra-pure helium as the carrier gas, achieves complete extraction of N2O and CH4 in a water sample and separation among N2O, CH4, and the other component gases. The flow path subsequent to gas chromatograph was periodically changed to pass the gases through the combustion furnace to convert CH4 and the other hydrocarbons into CO2, or to bypass the combustion furnace for the direct introduction of eluted N2O into the mass spectrometer, for determining the stable isotopic compositions through monitoring m/z = 44, 45, and 46, on the bases of CO2+ and N2O+, respectively. The analytical system can be operated automatically with sequential software programmed on a personal computer. The analytical precisions (the standard deviation of a single measurement) were better than 0.2‰ for δ15N of N2O and 0.3‰ for δ18O of N2O, in the case of more than 6.7 nmol N2O injection and better than 1.4‰ for δ15N of N2O and 2.6‰ for δ18O of N2O, in the case of more than 0.2 nmol N2O injection, respectively. Simultaneously, the analytical precisions were better than 0.07‰ for δ13C of CH4, in the case of more than 5.5 nmol CH4 infection and better than 2.1‰ for δ13C of CH4, when more than 0.024 nmol CH4 injection. In this manner, we can simultaneously determine stable isotopic compositions of a 120 mL water sample having

  19. Isotopic signature of N(2)O produced by marine ammonia-oxidizing archaea.

    PubMed

    Santoro, Alyson E; Buchwald, Carolyn; McIlvin, Matthew R; Casciotti, Karen L

    2011-09-02

    The ocean is an important global source of nitrous oxide (N(2)O), a greenhouse gas that contributes to stratospheric ozone destruction. Bacterial nitrification and denitrification are thought to be the primary sources of marine N(2)O, but the isotopic signatures of N(2)O produced by these processes are not consistent with the marine contribution to the global N(2)O budget. Based on enrichment cultures, we report that archaeal ammonia oxidation also produces N(2)O. Natural-abundance stable isotope measurements indicate that the produced N(2)O had bulk δ(15)N and δ(18)O values higher than observed for ammonia-oxidizing bacteria but similar to the δ(15)N and δ(18)O values attributed to the oceanic N(2)O source to the atmosphere. Our results suggest that ammonia-oxidizing archaea may be largely responsible for the oceanic N(2)O source.

  20. Nitrous oxide in fresh water systems: An estimate for the yield of atmospheric N2O associated with disposal of human waste

    NASA Technical Reports Server (NTRS)

    Kaplan, W. A.; Elkins, J. W.; Kolb, C. E.; Mcelroy, M. B.; Wofsy, S. C.; Duran, A. P.

    1977-01-01

    The N2O content of waters in the Potomac and Merrimack Rivers was measured on a number of occasions over the period April to July 1977. The concentrations of dissolved N2O exceeded those which would apply in equilibrium with air by factors ranging from about 46 in the Potomac to 1.2 in the Merrimack. Highest concentrations of dissolved N2O were associated with sewage discharges from the vicinity of Washington, D. C., and analysis indicates a relatively high yield, 1.3 to 11%, for prompt conversion of waste nitrogen to N2O. Measurements of dissolved N2O in fresh water ponds near Boston demonstrated that aquatic systems provide both strong sources and sinks for atmospheric N2O.

  1. 21 CFR 184.1545 - Nitrous oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Nitrous oxide. 184.1545 Section 184.1545 Food and... Substances Affirmed as GRAS § 184.1545 Nitrous oxide. (a) Nitrous oxide (empirical formula N2O, CAS Reg. No.... Nitrous oxide is manufactured by the thermal decomposition of ammonium nitrate. Higher oxides of...

  2. 21 CFR 184.1545 - Nitrous oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Nitrous oxide. 184.1545 Section 184.1545 Food and... Substances Affirmed as GRAS § 184.1545 Nitrous oxide. (a) Nitrous oxide (empirical formula N2O, CAS Reg. No.... Nitrous oxide is manufactured by the thermal decomposition of ammonium nitrate. Higher oxides of...

  3. 21 CFR 184.1545 - Nitrous oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Nitrous oxide. 184.1545 Section 184.1545 Food and... Substances Affirmed as GRAS § 184.1545 Nitrous oxide. (a) Nitrous oxide (empirical formula N2O, CAS Reg. No.... Nitrous oxide is manufactured by the thermal decomposition of ammonium nitrate. Higher oxides of...

  4. 21 CFR 184.1545 - Nitrous oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Nitrous oxide. 184.1545 Section 184.1545 Food and... Substances Affirmed as GRAS § 184.1545 Nitrous oxide. (a) Nitrous oxide (empirical formula N2O, CAS Reg. No.... Nitrous oxide is manufactured by the thermal decomposition of ammonium nitrate. Higher oxides of...

  5. 40 CFR Table Jj-7 to Subpart Jj of... - Nitrous Oxide Emission Factors (kg N2O-N/kg Kjdl N)

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) 0.07 Deep bedding for cattle and swine (no mix) 0.01 Manure Composting (in vessel) 0.006 Manure... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Manure Management... N2O-N/kg Kjdl N) Manure management system component N2O emission factor Uncovered anaerobic lagoon...

  6. 21 CFR 184.1545 - Nitrous oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Nitrous oxide. 184.1545 Section 184.1545 Food and....1545 Nitrous oxide. (a) Nitrous oxide (empirical formula N2O, CAS Reg. No. 10024-97-2) is also known as... slightly sweet smell. It does not burn but will support combustion. Nitrous oxide is manufactured by...

  7. Archaea produce lower yields of N2 O than bacteria during aerobic ammonia oxidation in soil.

    PubMed

    Hink, Linda; Nicol, Graeme W; Prosser, James I

    2016-03-11

    Nitrogen fertilisation of agricultural soil contributes significantly to emissions of the potent greenhouse gas nitrous oxide (N2 O), which is generated during denitrification and, in oxic soils, mainly by ammonia oxidisers. Although laboratory cultures of ammonia oxidising bacteria (AOB) and archaea (AOA) produce N2 O, their relative activities in soil are unknown. This work tested the hypothesis that AOB dominate ammonia oxidation and N2 O production under conditions of high inorganic ammonia (NH3 ) input, but result mainly from the activity of AOA when NH3 is derived from mineralisation. 1-octyne, a recently discovered inhibitor of AOB, was used to distinguish N2 O production resulting from archaeal and bacterial ammonia oxidation in soil microcosms, and specifically inhibited AOB growth, activity and N2 O production. In unamended soils, ammonia oxidation and N2 O production were lower and resulted mainly from ammonia oxidation by AOA. The AOA N2 O yield relative to nitrite produced was half that of AOB, likely due to additional enzymatic mechanisms in the latter, but ammonia oxidation and N2 O production were directly linked in all treatments. Relative contributions of AOA and AOB to N2 O production, therefore, reflect their respective contributions to ammonia oxidation. These results suggest potential mitigation strategies for N2 O emissions from fertilised agricultural soils.

  8. Isotope signatures of N2O emitted from vegetable soil: Ammonia oxidation drives N2O production in NH4+-fertilized soil of North China

    PubMed Central

    Zhang, Wei; Li, Yuzhong; Xu, Chunying; Li, Qiaozhen; Lin, Wei

    2016-01-01

    Nitrous oxide (N2O) is a potent greenhouse gas. In North China, vegetable fields are amended with high levels of N fertilizer and irrigation water, which causes massive N2O flux. The aim of this study was to determine the contribution of microbial processes to N2O production and characterize isotopic signature effects on N2O source partitioning. We conducted a microcosm study that combined naturally abundant isotopologues and gas inhibitor techniques to analyze N2O flux and its isotopomer signatures [δ15Nbulk, δ18O, and SP (intramolecular 15N site preference)] that emitted from vegetable soil after the addition of NH4+ fertilizers. The results show that ammonia oxidation is the predominant process under high water content (70% water-filled pore space), and nitrifier denitrification contribution increases with increasing N content. δ15Nbulk and δ18O of N2O may not provide information about microbial processes due to great shifts in precursor signatures and atom exchange, especially for soil treated with NH4+ fertilizer. SP and associated two end-member mixing model are useful to distinguish N2O source and contribution. Further work is needed to explore isotopomer signature stability to improve N2O microbial process identification. PMID:27387280

  9. Isotope signatures of N2O emitted from vegetable soil: Ammonia oxidation drives N2O production in NH4+-fertilized soil of North China

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Li, Yuzhong; Xu, Chunying; Li, Qiaozhen; Lin, Wei

    2016-07-01

    Nitrous oxide (N2O) is a potent greenhouse gas. In North China, vegetable fields are amended with high levels of N fertilizer and irrigation water, which causes massive N2O flux. The aim of this study was to determine the contribution of microbial processes to N2O production and characterize isotopic signature effects on N2O source partitioning. We conducted a microcosm study that combined naturally abundant isotopologues and gas inhibitor techniques to analyze N2O flux and its isotopomer signatures [δ15Nbulk, δ18O, and SP (intramolecular 15N site preference)] that emitted from vegetable soil after the addition of NH4+ fertilizers. The results show that ammonia oxidation is the predominant process under high water content (70% water-filled pore space), and nitrifier denitrification contribution increases with increasing N content. δ15Nbulk and δ18O of N2O may not provide information about microbial processes due to great shifts in precursor signatures and atom exchange, especially for soil treated with NH4+ fertilizer. SP and associated two end-member mixing model are useful to distinguish N2O source and contribution. Further work is needed to explore isotopomer signature stability to improve N2O microbial process identification.

  10. Nitrous oxide availability.

    PubMed

    Murray, M J; Murray, W J

    1980-04-01

    Nitrous oxide (N2O) is marketed as an inhalation anesthetic and as a food ingredient (e.g., whipping cream propellant). In the human, inhalation has been associated with "highs," peripheral nerve damage, mitotic poisoning of bone marrow, psychosis, and mental impairment. Exposure to hypoxemic mixtures has resulted in death. The commercial N2O sources specifically studied were aerosol whipping cream containers (three brands) and 6.5-cm cylinders, or chargers (two brands). The gas content and N2O concentrations of these devices were measured. The aerosol cans, when not shaken, will dispense at least 3 liters of 87 to 90% N2O. Charger misuse may occur when they are substituted for identically designed carbon dioxide (CO2) chargers of a seltzer bottle; 4.3 to 5.0 liters of 93 to 98% N2O is expelled at a controllable rate. The toxicity of these inexpensive N2O products, their high potential for misuse, and the absence of labeling (chargers) argue that their distribution be discontinued.

  11. Ammonium sorption and ammonia inhibition of nitrite-oxidizing bacteria explain contrasting soil N2O production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Better understanding of process controls over nitrous oxide (N2O) production in urine-impacted ‘hot spots’ and fertilizer bands is needed to improve mitigation strategies and emission models. Following amendment with bovine (Bos taurus) urine (Bu) or urea (Ur), we measured inorganic N, pH, N2O, and...

  12. Nitrous oxide and oxygen sedation: an update.

    PubMed

    Brunick, Ann; Clark, Morris S

    2013-01-01

    This course will teach the desirable characteristics of nitrous oxide, indications and contraindications for N2O/O2 use, as well as facts and myths surrounding chronic exposure to nitrous oxide, the biologic effects associated with high levels of the gas, and ways to assess and minimize trace gas contamination in an outpatient setting.

  13. Nitrogen management to reduce nitrous oxide emissions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) emissions from agricultural soils represent a complex interaction between the inputs of nitrogen into the soil and the soil environment. Mitigating these emissions will have a positive impact on greenhouse gases. Agriculture is the primary source of N2O emissions and must develop...

  14. Nitrous Oxide In The Antarctic Stratosphere

    NASA Technical Reports Server (NTRS)

    Podolske, J. R.; Loewenstein, M.; Strahan, S. E.; Chan, K. R.

    1991-01-01

    Paper reports on measurements of nitrous oxide (N2O) in upper atmosphere of Southern Hemisphere, made by tunable-laser absorption spectrometer on airplane. Measurements fill gap in information about distribution of N2O over Antarctic while ozone hole forming.

  15. Ammonia oxidation pathways and nitrifier denitrification are significant sources of N2O and NO under low oxygen availability

    PubMed Central

    Zhu, Xia; Burger, Martin; Doane, Timothy A.; Horwath, William R.

    2013-01-01

    The continuous increase of nitrous oxide (N2O) abundance in the atmosphere is a global concern. Multiple pathways of N2O production occur in soil, but their significance and dependence on oxygen (O2) availability and nitrogen (N) fertilizer source are poorly understood. We examined N2O and nitric oxide (NO) production under 21%, 3%, 1%, 0.5%, and 0% (vol/vol) O2 concentrations following urea or ammonium sulfate [(NH4)2SO4] additions in loam, clay loam, and sandy loam soils that also contained ample nitrate. The contribution of the ammonia (NH3) oxidation pathways (nitrifier nitrification, nitrifier denitrification, and nitrification-coupled denitrification) and heterotrophic denitrification (HD) to N2O production was determined in 36-h incubations in microcosms by 15N-18O isotope and NH3 oxidation inhibition (by 0.01% acetylene) methods. Nitrous oxide and NO production via NH3 oxidation pathways increased as O2 concentrations decreased from 21% to 0.5%. At low (0.5% and 3%) O2 concentrations, nitrifier denitrification contributed between 34% and 66%, and HD between 34% and 50% of total N2O production. Heterotrophic denitrification was responsible for all N2O production at 0% O2. Nitrifier denitrification was the main source of N2O production from ammonical fertilizer under low O2 concentrations with urea producing more N2O than (NH4)2SO4 additions. These findings challenge established thought attributing N2O emissions from soils with high water content to HD due to presumably low O2 availability. Our results imply that management practices that increase soil aeration, e.g., reducing compaction and enhancing soil structure, together with careful selection of fertilizer sources and/or nitrification inhibitors, could decrease N2O production in agricultural soils. PMID:23576736

  16. Acidification Enhances Hybrid N2O Production Associated with Aquatic Ammonia-Oxidizing Microorganisms

    PubMed Central

    Frame, Caitlin H.; Lau, Evan; Nolan, E. Joseph; Goepfert, Tyler J.; Lehmann, Moritz F.

    2017-01-01

    Ammonia-oxidizing microorganisms are an important source of the greenhouse gas nitrous oxide (N2O) in aquatic environments. Identifying the impact of pH on N2O production by ammonia oxidizers is key to understanding how aquatic greenhouse gas fluxes will respond to naturally occurring pH changes, as well as acidification driven by anthropogenic CO2. We assessed N2O production rates and formation mechanisms by communities of ammonia-oxidizing bacteria (AOB) and archaea (AOA) in a lake and a marine environment, using incubation-based nitrogen (N) stable isotope tracer methods with 15N-labeled ammonium (15NH4+) and nitrite (15NO2−), and also measurements of the natural abundance N and O isotopic composition of dissolved N2O. N2O production during incubations of water from the shallow hypolimnion of Lake Lugano (Switzerland) was significantly higher when the pH was reduced from 7.54 (untreated pH) to 7.20 (reduced pH), while ammonia oxidation rates were similar between treatments. In all incubations, added NH4+ was the source of most of the N incorporated into N2O, suggesting that the main N2O production pathway involved hydroxylamine (NH2OH) and/or NO2− produced by ammonia oxidation during the incubation period. A small but significant amount of N derived from exogenous/added 15NO2− was also incorporated into N2O, but only during the reduced-pH incubations. Mass spectra of this N2O revealed that NH4+ and 15NO2− each contributed N equally to N2O by a “hybrid-N2O” mechanism consistent with a reaction between NH2OH and NO2−, or compounds derived from these two molecules. Nitrifier denitrification was not an important source of N2O. Isotopomeric N2O analyses in Lake Lugano were consistent with incubation results, as 15N enrichment of the internal N vs. external N atoms produced site preferences (25.0–34.4‰) consistent with NH2OH-dependent hybrid-N2O production. Hybrid-N2O formation was also observed during incubations of seawater from coastal Namibia

  17. Nitrous oxide emissions from a commerical cattle feedlot in Kansas

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Emission of greenhouse gases, including nitrous oxide (N2O), from open beef cattle feedlots is becoming a concern. Research measuring emission rates of N2O from open beef cattle feedlots, however, has been limited. This study was conducted to quantify the N2O emission rate from pen surfaces in a com...

  18. Nitrous oxide emission from denitrification in stream and river networks

    EPA Science Inventory

    Nitrous oxide (N2O) is a potent greenhouse gas that contributes to climate change and stratospheric ozone destruction. Anthropogenic nitrogen (N) loading to river networks is a potentially important source of N2O via microbial denitrification which converts N to N2O and dinitrog...

  19. Sources of atmospheric nitrous oxide from combustion

    NASA Technical Reports Server (NTRS)

    Hao, W. M.; Wofsy, S. C.; Mcelroy, M. B.; Beer, J. M.; Toqan, M. A.

    1987-01-01

    Emissions of nitrous oxide (N2O) have been analyzed from industrial boilers and from a large experimental combustor burning natural gas, oil, or coal. Production of N2O and production of NO(x) were observed to be correlated, with an average molar ratio of 0.58:1 (N2O-N:NO). In conventional single-stage combustors, about 14 percent of fuel nitrogen is converted to N2O and 24 percent is converted to NO(x). Conversion of fuel nitrogen to N2O was much less efficient in a two-stage experimental combustor and in wood fires. A model is presented describing emissions of N2O globally, from the beginning of the industrial revolution to the present. It is expected that concentrations of N2O should rise more than 20 percent to about 367 ppb by the year 2050, based on conservative projections of world energy consumption.

  20. Global oceanic production of nitrous oxide.

    PubMed

    Freing, Alina; Wallace, Douglas W R; Bange, Hermann W

    2012-05-05

    We use transient time distributions calculated from tracer data together with in situ measurements of nitrous oxide (N(2)O) to estimate the concentration of biologically produced N(2)O and N(2)O production rates in the ocean on a global scale. Our approach to estimate the N(2)O production rates integrates the effects of potentially varying production and decomposition mechanisms along the transport path of a water mass. We estimate that the oceanic N(2)O production is dominated by nitrification with a contribution of only approximately 7 per cent by denitrification. This indicates that previously used approaches have overestimated the contribution by denitrification. Shelf areas may account for only a negligible fraction of the global production; however, estuarine sources and coastal upwelling of N(2)O are not taken into account in our study. The largest amount of subsurface N(2)O is produced in the upper 500 m of the water column. The estimated global annual subsurface N(2)O production ranges from 3.1 ± 0.9 to 3.4 ± 0.9 Tg N yr(-1). This is in agreement with estimates of the global N(2)O emissions to the atmosphere and indicates that a N(2)O source in the mixed layer is unlikely. The potential future development of the oceanic N(2)O source in view of the ongoing changes of the ocean environment (deoxygenation, warming, eutrophication and acidification) is discussed.

  1. Global oceanic production of nitrous oxide

    PubMed Central

    Freing, Alina; Wallace, Douglas W. R.; Bange, Hermann W.

    2012-01-01

    We use transient time distributions calculated from tracer data together with in situ measurements of nitrous oxide (N2O) to estimate the concentration of biologically produced N2O and N2O production rates in the ocean on a global scale. Our approach to estimate the N2O production rates integrates the effects of potentially varying production and decomposition mechanisms along the transport path of a water mass. We estimate that the oceanic N2O production is dominated by nitrification with a contribution of only approximately 7 per cent by denitrification. This indicates that previously used approaches have overestimated the contribution by denitrification. Shelf areas may account for only a negligible fraction of the global production; however, estuarine sources and coastal upwelling of N2O are not taken into account in our study. The largest amount of subsurface N2O is produced in the upper 500 m of the water column. The estimated global annual subsurface N2O production ranges from 3.1 ± 0.9 to 3.4 ± 0.9 Tg N yr−1. This is in agreement with estimates of the global N2O emissions to the atmosphere and indicates that a N2O source in the mixed layer is unlikely. The potential future development of the oceanic N2O source in view of the ongoing changes of the ocean environment (deoxygenation, warming, eutrophication and acidification) is discussed. PMID:22451110

  2. Greenhouse effect due to atmospheric nitrous oxide

    NASA Technical Reports Server (NTRS)

    Yung, Y. L.; Wang, W. C.; Lacis, A. A.

    1976-01-01

    The greenhouse effect due to nitrous oxide in the present atmosphere is about 0.8 K. Increase in atmospheric N2O due to perturbation of the nitrogen cycle by man may lead to an increase in surface temperature as large as 0.5 K by 2025, or 1.0 K by 2100. Other climatic effects of N2O are briefly discussed.

  3. Ammonium sorption and ammonia inhibition of nitrite-oxidizing bacteria explain contrasting soil N2O production

    NASA Astrophysics Data System (ADS)

    Venterea, R. T.; Sadowsky, M.; Breuillin-Sessoms, F.; Wang, P.; Clough, T. J.; Coulter, J. A.

    2015-12-01

    Better understanding of process controls over nitrous oxide (N2O) production in urine-impacted 'hot spots' and fertilizer bands is needed to improve mitigation strategies and emission models. Following amendment with bovine (Bos taurus) urine (Bu) or urea (Ur), we measured inorganic N, pH, N2O, and genes associated with nitrification in two soils ('L' and 'W') having similar texture, pH, C, and C/N ratio. Solution-phase ammonia (slNH3) was also calculated accounting for non-linear ammonium (NH4+) sorption capacities (ASC). Soil W displayed greater nitrification rates and nitrate (NO3-) levels than soil L, but was more resistant to nitrite (NO2-) accumulation and produced two to ten times less N2O than soil L. Genes associated with NO2- oxidation (nxrA) increased substantially in soil W but remained static in soil L. Soil NO2- was strongly correlated with N2O production, and cumulative (c-) slNH3 explained 87% of the variance in c-NO2-. Differences between soils were explained by greater slNH3 in soil L which inhibited NO2- oxidization leading to greater NO2- levels and N2O production. This is the first study to correlate the dynamics of soil slNH3, NO2-, N2O and nitrifier genes, and the first to show how ASC can regulate NO2- levels and N2O production.

  4. Ammonium sorption and ammonia inhibition of nitrite-oxidizing bacteria explain contrasting soil N2O production.

    PubMed

    Venterea, Rodney T; Clough, Timothy J; Coulter, Jeffrey A; Breuillin-Sessoms, Florence; Wang, Ping; Sadowsky, Michael J

    2015-07-16

    Better understanding of process controls over nitrous oxide (N2O) production in urine-impacted 'hot spots' and fertilizer bands is needed to improve mitigation strategies and emission models. Following amendment with bovine (Bos taurus) urine (Bu) or urea (Ur), we measured inorganic N, pH, N2O, and genes associated with nitrification in two soils ('L' and 'W') having similar texture, pH, C, and C/N ratio. Solution-phase ammonia (slNH3) was also calculated accounting for non-linear ammonium (NH4(+)) sorption capacities (ASC). Soil W displayed greater nitrification rates and nitrate (NO3(-)) levels than soil L, but was more resistant to nitrite (NO2(-)) accumulation and produced two to ten times less N2O than soil L. Genes associated with NO2(-) oxidation (nxrA) increased substantially in soil W but remained static in soil L. Soil NO2(-) was strongly correlated with N2O production, and cumulative (c-) slNH3 explained 87% of the variance in c-NO2(-). Differences between soils were explained by greater slNH3 in soil L which inhibited NO2(-) oxidization leading to greater NO2(-) levels and N2O production. This is the first study to correlate the dynamics of soil slNH3, NO2(-), N2O and nitrifier genes, and the first to show how ASC can regulate NO2(-) levels and N2O production.

  5. Ammonium sorption and ammonia inhibition of nitrite-oxidizing bacteria explain contrasting soil N2O production

    NASA Astrophysics Data System (ADS)

    Venterea, Rodney T.; Clough, Timothy J.; Coulter, Jeffrey A.; Breuillin-Sessoms, Florence

    2015-07-01

    Better understanding of process controls over nitrous oxide (N2O) production in urine-impacted ‘hot spots’ and fertilizer bands is needed to improve mitigation strategies and emission models. Following amendment with bovine (Bos taurus) urine (Bu) or urea (Ur), we measured inorganic N, pH, N2O, and genes associated with nitrification in two soils (‘L’ and ‘W’) having similar texture, pH, C, and C/N ratio. Solution-phase ammonia (slNH3) was also calculated accounting for non-linear ammonium (NH4+) sorption capacities (ASC). Soil W displayed greater nitrification rates and nitrate (NO3-) levels than soil L, but was more resistant to nitrite (NO2-) accumulation and produced two to ten times less N2O than soil L. Genes associated with NO2- oxidation (nxrA) increased substantially in soil W but remained static in soil L. Soil NO2- was strongly correlated with N2O production, and cumulative (c-) slNH3 explained 87% of the variance in c-NO2-. Differences between soils were explained by greater slNH3 in soil L which inhibited NO2- oxidization leading to greater NO2- levels and N2O production. This is the first study to correlate the dynamics of soil slNH3, NO2-, N2O and nitrifier genes, and the first to show how ASC can regulate NO2- levels and N2O production.

  6. Biocathodic nitrous oxide removal in bioelectrochemical systems.

    PubMed

    Desloover, Joachim; Puig, Sebastià; Virdis, Bernardino; Clauwaert, Peter; Boeckx, Pascal; Verstraete, Willy; Boon, Nico

    2011-12-15

    Anthropogenic nitrous oxide (N(2)O) emissions represent up to 40% of the global N(2)O emission and are constantly increasing. Mitigation of these emissions is warranted since N(2)O is a strong greenhouse gas and important ozone-depleting compound. Until now, only physicochemical technologies have been applied to mitigate point sources of N(2)O, and no biological treatment technology has been developed so far. In this study, a bioelectrochemical system (BES) with an autotrophic denitrifying biocathode was considered for the removal of N(2)O. The high N(2)O removal rates obtained ranged between 0.76 and 1.83 kg N m(-3) net cathodic compartment (NCC) d(-1) and were proportional to the current production, resulting in cathodic coulombic efficiencies near 100%. Furthermore, our experiments suggested the active involvement of microorganisms as the catalyst for the reduction of N(2)O to N(2), and the optimal cathode potential ranged from -200 to 0 mV vs standard hydrogen electrode (SHE) in order to obtain high conversion rates. Successful operation of the system for more than 115 days with N(2)O as the sole cathodic electron acceptor strongly indicated that N(2)O respiration yielded enough energy to maintain the biological process. To our knowledge, this study provides for the first time proof of concept of biocathodic N(2)O removal at long-term without the need for high temperatures and expensive catalysts.

  7. The effect of dissolved oxygen on N2O production by ammonia-oxidizing bacteria in an enriched nitrifying sludge.

    PubMed

    Peng, Lai; Ni, Bing-Jie; Erler, Dirk; Ye, Liu; Yuan, Zhiguo

    2014-12-01

    Dissolved oxygen (DO) is commonly recognized as an important factor influencing nitrous oxide (N2O) production by ammonia-oxidizing bacteria (AOB). However, it has been difficult to separate the true effect of DO from that of nitrite, as DO variation often affects nitrite accumulation. The effect of DO on N2O production by an enriched nitrifying sludge, consisting of both AOB and nitrite-oxidizing bacteria (NOB), was investigated in this study. Nitrite accumulation was minimised by augmenting nitrite oxidation through the addition of an enriched NOB sludge. It was demonstrated that the specific N2O production rate increased from 0 to 1.9 ± 0.09 (n = 3) mg N2O-N/hr/g VSS with an increase of DO concentration from 0 to 3.0 mg O2/L, whereas N2O emission factor (the ratio between N2O nitrogen emitted and the ammonium nitrogen converted) decreased from 10.6 ± 1.7% (n = 3) at DO = 0.2 mg O2/L to 2.4 ± 0.1% (n = 3) at DO = 3.0 mg O2/L. The site preference measurements indicated that both the AOB denitrification and hydroxylamine (NH2OH) oxidation pathways contributed to N2O production, and DO had an important effect on the relative contributions of the two pathways. This finding is supported by analysis of the process data using an N2O model describing both pathways. As DO increased from 0.2 to 3.0 mg O2/L, the contribution of AOB denitrification decreased from 92% - 95%-66% - 73%, accompanied by a corresponding increase in the contribution by the NH2OH oxidation pathway.

  8. Prehospital analgesia with nitrous oxide/oxygen.

    PubMed Central

    McKinnon, K. D.

    1981-01-01

    A pilot study of prehospital analgesia with 50% nitrous oxide and 50% oxygen was undertaken in patients experiencing severe pain from various sources. Under the supervision of an ambulance attendant N2O/O2 was administered through a face mask held by the patient and connected to a portable regulator/tank unit. Two types of units were evaluated -- Entonox (with premixed N2O and O2) and Nitronox (with separate cylinders of N2O and O2, the gases being mixed at the time of administration). Of the 72 patients 69 obtained worthwhile analgesia (marked or partial relief of pain) during treatment in the field or in the ambulance. There were no serious side effects, and those that did occur reflected N2O's expected action (e.g., giddiness). N2O/O2 is thus considered a safe and effective analgesic, suitable for use by ambulance personnel. Images FIG. 1 FIG. 2 PMID:7306895

  9. NITROUS OXIDE EMISSIONS FROM FOSSIL FUEL COMBUSTION

    EPA Science Inventory

    The role of coal combustion as a significant global source of nitrous oxide (N2O) emissions was reexamined through on-line emission measurements from six pulverized-coal-fired utility boilers and from laboratory and pilot-scale combustors. The full-scale utility boilers yielded d...

  10. Photo release of nitrous oxide from the hyponitrite ion studied by infrared spectroscopy. Evidence for the generation of a cobalt-N2O complex. Experimental and DFT calculations.

    PubMed

    Chacón Villalba, M Elizabeth; Franca, Carlos A; Güida, Jorge A

    2017-04-05

    The solid state photolysis of sodium, silver and thallium hyponitrite (M2N2O2, M=Na, Ag, Tl) salts and a binuclear complex of cobalt bridged by hyponitrite ([Co(NH3)5-N(O)-NO-Co(NH3)5](4+)) were studied by irradiation with visible and UV light in the electronic absorption region. The UV-visible spectra for free hyponitrite ion and binuclear complex of cobalt were interpreted in terms of Density Functional Theory calculations in order to explain photolysis behavior. The photolysis of each compound depends selectively on the irradiation wavelength. Irradiation with 340-460nm light and with the 488nm laser line generates photolysis only in silver and thallium hyponitrite salts, while 253.7nm light photolyzed all the studied compounds. Infrared spectroscopy was used to follow the photolysis process and to identify the generated products. Remarkably, gaseous N2O was detected after photolysis in the infrared spectra of sodium, silver, and thallium hyponitrite KBr pellets. The spectra for [Co(NH3)5-N(O)-NO-Co(NH3)5](4+) suggest that one cobalt ion remains bonded to N2O from which the generation of a [(NH3)5CoNNO](+3) complex is inferred. Density Functional Theory (DFT) based calculations confirm the stability of this last complex and provide the theoretical data which are used in the interpretation of the electronic spectra of the hyponitrite ion and the cobalt binuclear complex and thus in the elucidation of their photolysis behavior. Carbonate ion is also detected after photolysis in all studied compounds, presumably due to the reaction of atmospheric CO2 with the microcrystal surface reaction products. Kinetic measurements for the photolysis of the binuclear complex suggest a first order law for the intensity decay of the hyponitrite IR bands and for the intensity increase in the N2O generation. Predicted and experimental data are in very good agreement.

  11. Photo release of nitrous oxide from the hyponitrite ion studied by infrared spectroscopy. Evidence for the generation of a cobalt-N2O complex. Experimental and DFT calculations

    NASA Astrophysics Data System (ADS)

    Chacón Villalba, M. Elizabeth; Franca, Carlos A.; Güida, Jorge A.

    2017-04-01

    The solid state photolysis of sodium, silver and thallium hyponitrite (M2N2O2, M = Na, Ag, Tl) salts and a binuclear complex of cobalt bridged by hyponitrite ([Co(NH3)5-N(O)-NO-Co(NH3)5]4 +) were studied by irradiation with visible and UV light in the electronic absorption region. The UV-visible spectra for free hyponitrite ion and binuclear complex of cobalt were interpreted in terms of Density Functional Theory calculations in order to explain photolysis behavior. The photolysis of each compound depends selectively on the irradiation wavelength. Irradiation with 340-460 nm light and with the 488 nm laser line generates photolysis only in silver and thallium hyponitrite salts, while 253.7 nm light photolyzed all the studied compounds. Infrared spectroscopy was used to follow the photolysis process and to identify the generated products. Remarkably, gaseous N2O was detected after photolysis in the infrared spectra of sodium, silver, and thallium hyponitrite KBr pellets. The spectra for [Co(NH3)5-N(O)-NO-Co(NH3)5]4 + suggest that one cobalt ion remains bonded to N2O from which the generation of a [(NH3)5CoNNO]+ 3 complex is inferred. Density Functional Theory (DFT) based calculations confirm the stability of this last complex and provide the theoretical data which are used in the interpretation of the electronic spectra of the hyponitrite ion and the cobalt binuclear complex and thus in the elucidation of their photolysis behavior. Carbonate ion is also detected after photolysis in all studied compounds, presumably due to the reaction of atmospheric CO2 with the microcrystal surface reaction products. Kinetic measurements for the photolysis of the binuclear complex suggest a first order law for the intensity decay of the hyponitrite IR bands and for the intensity increase in the N2O generation. Predicted and experimental data are in very good agreement.

  12. Nitrous oxide emissions from the Gulf of Mexico Hypoxic Zone

    EPA Science Inventory

    The production of nitrous oxide (N2O), a potent greenhouse gas, in hypoxic coastal zones remains poorly characterized due to a lack of data, though large nitrogen inputs and deoxygenation typical of these systems create the potential for large N2O emissions. We report the first N...

  13. Municipal gravity sewers: an unrecognised source of nitrous oxide

    EPA Science Inventory

    Nitrous oxide (N2O) is a primary ozone-depleting substance and powerful greenhouse gas. N2O emissions from secondary-level wastewater treatment processes are relatively well understood as a result of intensive international research effort in recent times, yet little information...

  14. Nitrous oxide emissions affected by biochar and nitrogen stabilizers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Both biochar and N fertilizer stabilizers (N transformation inhibitors) are potential strategies to reduce nitrous oxide (N2O) emissions from fertilization, but the mechanisms and/or N transformation processes affecting the N dynamics are not fully understood. This research investigated N2O emission...

  15. Effects of nitrogen fertilizer types on nitrous oxide emissions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The factors controlling nitrous oxide (N2O) emissions after fertilizer nitrogen (N) applications are well studied. This information can be used to choose appropriate fertilizer sources and placement methods in order to minimize direct fertilizer-induced N2O emissions in cropping systems. Several fie...

  16. Fatal abuse of nitrous oxide in the workplace.

    PubMed

    Suruda, A J; McGlothlin, J D

    1990-08-01

    Abuse of nitrous oxide (N2O) while on the job caused at least 11 deaths in 1984 to 1987, as found in investigations by the Occupational Safety and Health Administration and in reports to the Consumer Product Safety Commission. Although nitrous oxide has had a reputation as a "clean and safe" analgesic and anesthetic, the possibility of asphyxiation by inhalation is not widely recognized, and there are no requirements for warning labels on nonmedical sources of N2O. The 11 deaths involved recreational inhalation of N2O by young male employees from tanks or cylinders normally used for legitimate business purposes. In six cases, the victims worked in food serving establishments and inhaled N2O that was used to power whipped cream dispensers. Commercial users of N2O, particularly in the restaurant industry, should be aware of this hazard. Warning labels for N2O sources and tighter control over supplies are warranted.

  17. Recreational nitrous oxide use: Prevalence and risks.

    PubMed

    van Amsterdam, Jan; Nabben, Ton; van den Brink, Wim

    2015-12-01

    Nitrous oxide (N2O; laughing gas) is clinically used as a safe anesthetic (dentistry, ambulance, childbirth) and appreciated for its anti-anxiety effect. Since five years, recreational use of N2O is rapidly increasing especially in the dance and festival scene. In the UK, N2O is the second most popular recreational drug after cannabis. In most countries, nitrous oxide is a legal drug that is widely available and cheap. Last month prevalence of use among clubbers and ravers ranges between 40 and almost 80 percent. Following one inhalation, mostly from a balloon, a euphoric, pleasant, joyful, empathogenic and sometimes hallucinogenic effect is rapidly induced (within 10 s) and disappears within some minutes. Recreational N2O use is generally moderate with most users taking less than 10 balloons of N2O per episode and about 80% of the users having less than 10 episodes per year. Side effects of N2O include transient dizziness, dissociation, disorientation, loss of balance, impaired memory and cognition, and weakness in the legs. When intoxicated accidents like tripping and falling may occur. Some fatal accidents have been reported due to due to asphyxia (hypoxia). Heavy or sustained use of N2O inactivates vitamin B12, resulting in a functional vitamin B12 deficiency and initially causing numbness in fingers, which may further progress to peripheral neuropathy and megaloblastic anemia. N2O use does not seem to result in dependence. Considering the generally modest use of N2O and its relative safety, it is not necessary to take legal measures. However, (potential) users should be informed about the risk of vitamin B12-deficiency related neurological and hematological effects associated with heavy use.

  18. Nitrous oxide emission by aquatic macrofauna

    PubMed Central

    Stief, Peter; Poulsen, Morten; Nielsen, Lars Peter; Brix, Hans; Schramm, Andreas

    2009-01-01

    A large variety of aquatic animals was found to emit the potent greenhouse gas nitrous oxide when nitrate was present in the environment. The emission was ascribed to denitrification by ingested bacteria in the anoxic animal gut, and the exceptionally high N2O-to-N2 production ratio suggested delayed induction of the last step of denitrification. Filter- and deposit-feeding animal species showed the highest rates of nitrous oxide emission and predators the lowest, probably reflecting the different amounts of denitrifying bacteria in the diet. We estimate that nitrous oxide emission by aquatic animals is quantitatively important in nitrate-rich aquatic environments like freshwater, coastal marine, and deep-sea ecosystems. The contribution of this source to overall nitrous oxide emission from aquatic environments might further increase because of the projected increase of nitrate availability in tropical regions and the numeric dominance of filter- and deposit-feeders in eutrophic ecosystems. PMID:19255427

  19. Ammonium sorption and ammonia inhibition of nitrite-oxidizing bacteria explain contrasting soil N2O production

    PubMed Central

    Venterea, Rodney T.; Clough, Timothy J.; Coulter, Jeffrey A.; Breuillin-Sessoms, Florence

    2015-01-01

    Better understanding of process controls over nitrous oxide (N2O) production in urine-impacted ‘hot spots’ and fertilizer bands is needed to improve mitigation strategies and emission models. Following amendment with bovine (Bos taurus) urine (Bu) or urea (Ur), we measured inorganic N, pH, N2O, and genes associated with nitrification in two soils (‘L’ and ‘W’) having similar texture, pH, C, and C/N ratio. Solution-phase ammonia (slNH3) was also calculated accounting for non-linear ammonium (NH4+) sorption capacities (ASC). Soil W displayed greater nitrification rates and nitrate (NO3−) levels than soil L, but was more resistant to nitrite (NO2−) accumulation and produced two to ten times less N2O than soil L. Genes associated with NO2− oxidation (nxrA) increased substantially in soil W but remained static in soil L. Soil NO2− was strongly correlated with N2O production, and cumulative (c-) slNH3 explained 87% of the variance in c-NO2−. Differences between soils were explained by greater slNH3 in soil L which inhibited NO2− oxidization leading to greater NO2− levels and N2O production. This is the first study to correlate the dynamics of soil slNH3, NO2−, N2O and nitrifier genes, and the first to show how ASC can regulate NO2− levels and N2O production. PMID:26179972

  20. Death from Nitrous Oxide.

    PubMed

    Bäckström, Björn; Johansson, Bengt; Eriksson, Anders

    2015-11-01

    Nitrous oxide is an inflammable gas that gives no smell or taste. It has a history of abuse as long as its clinical use, and deaths, although rare, have been reported. We describe two cases of accidental deaths related to voluntary inhalation of nitrous oxide, both found dead with a gas mask covering the face. In an attempt to find an explanation to why the victims did not react properly to oncoming hypoxia, we performed experiments where a test person was allowed to breath in a closed system, with or without nitrous oxide added. Vital signs and gas concentrations as well as subjective symptoms were recorded. The experiments indicated that the explanation to the fact that neither of the descendents had reacted to oncoming hypoxia and hypercapnia was due to the inhalation of nitrous oxide. This study raises the question whether nitrous oxide really should be easily, commercially available.

  1. Effects of substrates on N2O emissions in an anaerobic ammonium oxidation (anammox) reactor.

    PubMed

    Jin, Yue; Wang, Dunqiu; Zhang, Wenjie

    2016-01-01

    N2O emission in the anaerobic ammonium oxidation (anammox) process is of growing concern. In this study, effects of substrate concentrations on N2O emissions were investigated in an anammox reactor. Extremely high N2O emissions of 1.67 % were led by high NH4-N concentrations. Results showed that N2O emissions have a positive correlation with NH4-N concentrations in the anammox reactor. Reducing NH4-N concentrations by recycling pump resulted in decreasing N2O emissions. In addition, further studies were performed to identify a key biological process that is contributed to N2O emissions from the anammox reactor. Based on the results obtained, Nitrosomonas, which can oxidize ammonia to nitrite, was deemed as the main sources of N2O emissions.

  2. Nitrous oxide fluxes from a commercial beef cattle feedlot in Kansas

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Emission of greenhouse gases, including nitrous oxide (N2O), from open beef cattle feedlots is becoming an environmental concern; however, research measuring emission rates of N2O from open beef cattle feedlots has been limited. This study was conducted to quantify N2O emission fluxes as affected by...

  3. Contemporary and projected biogenic fluxes of methane and nitrous oxide in North American terrestrial ecosystems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The importance of methane (CH4) and nitrous oxide (N2O) in determining global climate change has been increasingly recognized, but terrestrial CH4 and N2O budgets and the underlying mechanisms remain far from certain. Accurate estimation of terrestrial CH4 and N2O budgets would be a critical step fo...

  4. Nitrous oxide emissions from wastewater treatment processes

    PubMed Central

    Law, Yingyu; Ye, Liu; Pan, Yuting; Yuan, Zhiguo

    2012-01-01

    Nitrous oxide (N2O) emissions from wastewater treatment plants vary substantially between plants, ranging from negligible to substantial (a few per cent of the total nitrogen load), probably because of different designs and operational conditions. In general, plants that achieve high levels of nitrogen removal emit less N2O, indicating that no compromise is required between high water quality and lower N2O emissions. N2O emissions primarily occur in aerated zones/compartments/periods owing to active stripping, and ammonia-oxidizing bacteria, rather than heterotrophic denitrifiers, are the main contributors. However, the detailed mechanisms remain to be fully elucidated, despite strong evidence suggesting that both nitrifier denitrification and the chemical breakdown of intermediates of hydroxylamine oxidation are probably involved. With increased understanding of the fundamental reactions responsible for N2O production in wastewater treatment systems and the conditions that stimulate their occurrence, reduction of N2O emissions from wastewater treatment systems through improved plant design and operation will be achieved in the near future. PMID:22451112

  5. N2O FIELD STUDY

    EPA Science Inventory

    The report gives results of measurements of nitrous oxide (N2O) emissions from coal-fired utility boilers at three electric power generating stations. Six units were tested, two at each site, including sizes ranging from 165 to 700 MW. Several manufacturers and boiler firing type...

  6. Revision of N2O-producing pathways in the ammonia-oxidizing bacterium Nitrosomonas europaea ATCC 19718.

    PubMed

    Kozlowski, Jessica A; Price, Jennifer; Stein, Lisa Y

    2014-08-01

    Nitrite reductase (NirK) and nitric oxide reductase (NorB) have long been thought to play an essential role in nitrous oxide (N2O) production by ammonia-oxidizing bacteria. However, essential gaps remain in our understanding of how and when NirK and NorB are active and functional, putting into question their precise roles in N2O production by ammonia oxidizers. The growth phenotypes of the Nitrosomonas europaea ATCC 19718 wild-type and mutant strains deficient in expression of NirK, NorB, and both gene products were compared under atmospheric and reduced O2 tensions. Anoxic resting-cell assays and instantaneous nitrite (NO2 (-)) reduction experiments were done to assess the ability of the wild-type and mutant N. europaea strains to produce N2O through the nitrifier denitrification pathway. Results confirmed the role of NirK for efficient substrate oxidation of N. europaea and showed that NorB is involved in N2O production during growth at both atmospheric and reduced O2 tensions. Anoxic resting-cell assays and measurements of instantaneous NO2 (-) reduction using hydrazine as an electron donor revealed that an alternate nitrite reductase to NirK is present and active. These experiments also clearly demonstrated that NorB was the sole nitric oxide reductase for nitrifier denitrification. The results of this study expand the enzymology for nitrogen metabolism and N2O production by N. europaea and will be useful to interpret pathways in other ammonia oxidizers that lack NirK and/or NorB genes.

  7. Revision of N2O-Producing Pathways in the Ammonia-Oxidizing Bacterium Nitrosomonas europaea ATCC 19718

    PubMed Central

    Kozlowski, Jessica A.; Price, Jennifer

    2014-01-01

    Nitrite reductase (NirK) and nitric oxide reductase (NorB) have long been thought to play an essential role in nitrous oxide (N2O) production by ammonia-oxidizing bacteria. However, essential gaps remain in our understanding of how and when NirK and NorB are active and functional, putting into question their precise roles in N2O production by ammonia oxidizers. The growth phenotypes of the Nitrosomonas europaea ATCC 19718 wild-type and mutant strains deficient in expression of NirK, NorB, and both gene products were compared under atmospheric and reduced O2 tensions. Anoxic resting-cell assays and instantaneous nitrite (NO2−) reduction experiments were done to assess the ability of the wild-type and mutant N. europaea strains to produce N2O through the nitrifier denitrification pathway. Results confirmed the role of NirK for efficient substrate oxidation of N. europaea and showed that NorB is involved in N2O production during growth at both atmospheric and reduced O2 tensions. Anoxic resting-cell assays and measurements of instantaneous NO2− reduction using hydrazine as an electron donor revealed that an alternate nitrite reductase to NirK is present and active. These experiments also clearly demonstrated that NorB was the sole nitric oxide reductase for nitrifier denitrification. The results of this study expand the enzymology for nitrogen metabolism and N2O production by N. europaea and will be useful to interpret pathways in other ammonia oxidizers that lack NirK and/or NorB genes. PMID:24907318

  8. The combined effect of dissolved oxygen and nitrite on N2O production by ammonia oxidizing bacteria in an enriched nitrifying sludge.

    PubMed

    Peng, Lai; Ni, Bing-Jie; Ye, Liu; Yuan, Zhiguo

    2015-04-15

    Both nitrite [Formula: see text] and dissolved oxygen (DO) play important roles in nitrous oxide (N2O) production by ammonia oxidizing bacteria (AOB). However, few studies focused on the combined effect of them on N2O production by AOB as well as the corresponding mechanisms. In this study, N2O production by an enriched nitrifying sludge, consisting of both AOB and nitrite-oxidizing bacteria (NOB), was investigated under various [Formula: see text] and DO concentrations. At each investigated DO level, both the biomass specific N2O production rate and the N2O emission factor (the ratio between N2O nitrogen emitted and the ammonium nitrogen converted) increased as [Formula: see text] concentration increased from 3 mg N/L to 50 mg N/L. However, at each investigated [Formula: see text] level, the maximum biomass specific N2O production rate occurred at DO of 0.85 mg O2/L, while the N2O emission factor decreased as DO increased from 0.35 to 3.5 mg O2/L. The analysis of the process data using a mathematical N2O model incorporating both the AOB denitrification and hydroxylamine (NH2OH) oxidation pathways indicated that the contribution of AOB denitrification pathway increased as [Formula: see text] concentration increased, but decreased as DO concentration increased, accompanied by a corresponding change in the contribution of NH2OH oxidation pathway to N2O production. The AOB denitrification pathway was predominant in most cases, with the NH2OH oxidation pathway making a comparable contribution only at high DO level (e.g. 3.5 mg O2/L).

  9. N2O production by ammonia oxidizing bacteria in an enriched nitrifying sludge linearly depends on inorganic carbon concentration.

    PubMed

    Peng, Lai; Ni, Bing-Jie; Ye, Liu; Yuan, Zhiguo

    2015-05-01

    The effect of inorganic carbon (IC) on nitrous oxide (N2O) production by ammonia oxidizing bacteria (AOB) was investigated over a concentration range of 0-12 mmol C/L, encompassing typical IC levels in a wastewater treatment reactors. The AOB culture was enriched along with nitrite-oxidizing bacteria (NOB) in a sequencing batch reactor (SBR) to perform complete nitrification. Batch experiments were conducted with continuous carbon dioxide (CO2) stripping or at controlled IC concentrations. The results revealed a linear relationship between N2O production rate (N2OR) and IC concentration (R(2) = 0.97) within the IC range studied, suggesting a substantial effect of IC on N2O production by AOB. Similar results were also obtained with an AOB culture treating anaerobic sludge digestion liquor. The fundamental mechanism responsible for this dependency is unclear; however, in agreement with previous studies, it was observed that the ammonia oxidation rate (AOR) was also influenced by the IC concentration, which could be well described by the Monod kinetics. These resulted in an exponential relationship between N2OR and AOR, as previously observed in experiments where AOR was altered by varying dissolved oxygen and ammonia concentrations. It is therefore possible that IC indirectly affected N2OR by causing a change in AOR. The observation in this study indicates that alkalinity (mostly contributed by IC) could be a significant factor influencing N2O production and should be taken into consideration in estimating and mitigating N2O emissions in wastewater treatment systems.

  10. Isotopic signatures of N2O produced by ammonia-oxidizing archaea from soils

    PubMed Central

    Jung, Man-Young; Well, Reinhard; Min, Deullae; Giesemann, Anette; Park, Soo-Je; Kim, Jong-Geol; Kim, So-Jeong; Rhee, Sung-Keun

    2014-01-01

    N2O gas is involved in global warming and ozone depletion. The major sources of N2O are soil microbial processes. Anthropogenic inputs into the nitrogen cycle have exacerbated these microbial processes, including nitrification. Ammonia-oxidizing archaea (AOA) are major members of the pool of soil ammonia-oxidizing microorganisms. This study investigated the isotopic signatures of N2O produced by soil AOA and associated N2O production processes. All five AOA strains (I.1a, I.1a-associated and I.1b clades of Thaumarchaeota) from soil produced N2O and their yields were comparable to those of ammonia-oxidizing bacteria (AOB). The levels of site preference (SP), δ15Nbulk and δ18O -N2O of soil AOA strains were 13–30%, −13 to −35% and 22–36%, respectively, and strains MY1–3 and other soil AOA strains had distinct isotopic signatures. A 15N-NH4+-labeling experiment indicated that N2O originated from two different production pathways (that is, ammonia oxidation and nitrifier denitrification), which suggests that the isotopic signatures of N2O from AOA may be attributable to the relative contributions of these two processes. The highest N2O production yield and lowest site preference of acidophilic strain CS may be related to enhanced nitrifier denitrification for detoxifying nitrite. Previously, it was not possible to detect N2O from soil AOA because of similarities between its isotopic signatures and those from AOB. Given the predominance of AOA over AOB in most soils, a significant proportion of the total N2O emissions from soil nitrification may be attributable to AOA. PMID:24225887

  11. Nitrous oxide emission from denitrification in stream and river networks

    USGS Publications Warehouse

    Beaulieu, J.J.; Tank, J.L.; Hamilton, S.K.; Wollheim, W.M.; Hall, R.O.; Mulholland, P.J.; Peterson, B.J.; Ashkenas, L.R.; Cooper, L.W.; Dahm, Clifford N.; Dodds, W.K.; Grimm, N. B.; Johnson, S.L.; McDowell, W.H.; Poole, G.C.; Maurice, Valett H.; Arango, C.P.; Bernot, M.J.; Burgin, A.J.; Crenshaw, C.L.; Helton, A.M.; Johnson, L.T.; O'Brien, J. M.; Potter, J.D.; Sheibley, R.W.; Sobota, D.J.; Thomas, S.M.

    2011-01-01

    Nitrous oxide (N2O) is a potent greenhouse gas that contributes to climate change and stratospheric ozone destruction. Anthropogenic nitrogen (N) loading to river networks is a potentially important source of N 2O via microbial denitrification that converts N to N2O and dinitrogen (N2). The fraction of denitrified N that escapes as N2O rather than N2 (i.e., the N2O yield) is an important determinant of how much N2O is produced by river networks, but little is known about the N2O yield in flowing waters. Here, we present the results of whole-stream 15N-tracer additions conducted in 72 headwater streams draining multiple land-use types across the United States. We found that stream denitrification produces N2O at rates that increase with stream water nitrate (NO3-) concentrations, but that <1% of denitrified N is converted to N2O. Unlike some previous studies, we found no relationship between the N2O yield and stream water NO3-. We suggest that increased stream NO3- loading stimulates denitrification and concomitant N2O production, but does not increase the N2O yield. In our study, most streams were sources of N2O to the atmosphere and the highest emission rates were observed in streams draining urban basins. Using a global river network model, we estimate that microbial N transformations (e.g., denitrification and nitrification) convert at least 0.68 Tg??y -1 of anthropogenic N inputs to N2O in river networks, equivalent to 10% of the global anthropogenic N2O emission rate. This estimate of stream and river N2O emissions is three times greater than estimated by the Intergovernmental Panel on Climate Change.

  12. Nitrous oxide emission from denitrification in stream and river networks

    PubMed Central

    Beaulieu, Jake J.; Tank, Jennifer L.; Hamilton, Stephen K.; Wollheim, Wilfred M.; Hall, Robert O.; Mulholland, Patrick J.; Peterson, Bruce J.; Ashkenas, Linda R.; Cooper, Lee W.; Dahm, Clifford N.; Dodds, Walter K.; Grimm, Nancy B.; Johnson, Sherri L.; McDowell, William H.; Poole, Geoffrey C.; Valett, H. Maurice; Arango, Clay P.; Bernot, Melody J.; Burgin, Amy J.; Crenshaw, Chelsea L.; Helton, Ashley M.; Johnson, Laura T.; O'Brien, Jonathan M.; Potter, Jody D.; Sheibley, Richard W.; Sobota, Daniel J.; Thomas, Suzanne M.

    2011-01-01

    Nitrous oxide (N2O) is a potent greenhouse gas that contributes to climate change and stratospheric ozone destruction. Anthropogenic nitrogen (N) loading to river networks is a potentially important source of N2O via microbial denitrification that converts N to N2O and dinitrogen (N2). The fraction of denitrified N that escapes as N2O rather than N2 (i.e., the N2O yield) is an important determinant of how much N2O is produced by river networks, but little is known about the N2O yield in flowing waters. Here, we present the results of whole-stream 15N-tracer additions conducted in 72 headwater streams draining multiple land-use types across the United States. We found that stream denitrification produces N2O at rates that increase with stream water nitrate (NO3−) concentrations, but that <1% of denitrified N is converted to N2O. Unlike some previous studies, we found no relationship between the N2O yield and stream water NO3−. We suggest that increased stream NO3− loading stimulates denitrification and concomitant N2O production, but does not increase the N2O yield. In our study, most streams were sources of N2O to the atmosphere and the highest emission rates were observed in streams draining urban basins. Using a global river network model, we estimate that microbial N transformations (e.g., denitrification and nitrification) convert at least 0.68 Tg·y−1 of anthropogenic N inputs to N2O in river networks, equivalent to 10% of the global anthropogenic N2O emission rate. This estimate of stream and river N2O emissions is three times greater than estimated by the Intergovernmental Panel on Climate Change. PMID:21173258

  13. Nitrous oxide measurements in the eastern tropical Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Pierotti, D.; Rasmussen, R. A.

    1980-01-01

    The paper considers nitrous oxide measurements in the eastern tropical Pacific Ocean. The concentration of N2O in the marine air showed a direct relationship to the N2O in the surface sea water, with the highest N2O mixing ratios over highly supersaturated regions; water samples were also collected down to depths of 300 m at seven hydrocast stations. The stations showed two distribution patterns for N2O concentration vs depth for the region between the surface and 300 m; two stations in the oxygen deficient region off the coast of Peru showed considerable N2O super-saturation at all depths, and results indicate that the role of N2O in the nitrogen cycle of the ocean may be more complex than previously suggested.

  14. Sampling frequency affects estimates of annual nitrous oxide fluxes

    PubMed Central

    Barton, L.; Wolf, B.; Rowlings, D.; Scheer, C.; Kiese, R.; Grace, P.; Stefanova, K.; Butterbach-Bahl, K.

    2015-01-01

    Quantifying nitrous oxide (N2O) fluxes, a potent greenhouse gas, from soils is necessary to improve our knowledge of terrestrial N2O losses. Developing universal sampling frequencies for calculating annual N2O fluxes is difficult, as fluxes are renowned for their high temporal variability. We demonstrate daily sampling was largely required to achieve annual N2O fluxes within 10% of the ‘best’ estimate for 28 annual datasets collected from three continents—Australia, Europe and Asia. Decreasing the regularity of measurements either under- or overestimated annual N2O fluxes, with a maximum overestimation of 935%. Measurement frequency was lowered using a sampling strategy based on environmental factors known to affect temporal variability, but still required sampling more than once a week. Consequently, uncertainty in current global terrestrial N2O budgets associated with the upscaling of field-based datasets can be decreased significantly using adequate sampling frequencies. PMID:26522228

  15. Sampling frequency affects estimates of annual nitrous oxide fluxes

    NASA Astrophysics Data System (ADS)

    Barton, L.; Wolf, B.; Rowlings, D.; Scheer, C.; Kiese, R.; Grace, P.; Stefanova, K.; Butterbach-Bahl, K.

    2015-11-01

    Quantifying nitrous oxide (N2O) fluxes, a potent greenhouse gas, from soils is necessary to improve our knowledge of terrestrial N2O losses. Developing universal sampling frequencies for calculating annual N2O fluxes is difficult, as fluxes are renowned for their high temporal variability. We demonstrate daily sampling was largely required to achieve annual N2O fluxes within 10% of the ‘best’ estimate for 28 annual datasets collected from three continents—Australia, Europe and Asia. Decreasing the regularity of measurements either under- or overestimated annual N2O fluxes, with a maximum overestimation of 935%. Measurement frequency was lowered using a sampling strategy based on environmental factors known to affect temporal variability, but still required sampling more than once a week. Consequently, uncertainty in current global terrestrial N2O budgets associated with the upscaling of field-based datasets can be decreased significantly using adequate sampling frequencies.

  16. Isotopic fractionation by a fungal P450 nitric oxide reductase during the production of N2O.

    PubMed

    Yang, Hui; Gandhi, Hasand; Ostrom, Nathaniel E; Hegg, Eric L

    2014-09-16

    Nitrous oxide (N2O) is a potent greenhouse gas with a 100-year global warming potential approximately 300 times that of CO2. Because microbes account for over 75% of the N2O released in the U.S., understanding the biochemical processes by which N2O is produced is critical to our efforts to mitigate climate change. In the current study, we used gas chromatography-isotope ratio mass spectrometry (GC-IRMS) to measure the δ(15)N, δ(18)O, δ(15)N(α), and δ(15)N(β) of N2O generated by purified fungal nitric oxide reductase (P450nor) from Histoplasma capsulatum. The isotope values were used to calculate site preference (SP) values (difference in δ(15)N between the central (α) and terminal (β) N atoms in N2O), enrichment factors (ε), and kinetic isotope effects (KIEs). Both oxygen and N(α) displayed normal isotope effects during enzymatic NO reduction with ε values of -25.7‰ (KIE = 1.0264) and -12.6‰ (KIE = 1.0127), respectively. However, bulk nitrogen (average δ(15)N of N(α) and N(β)) and N(β) exhibited inverse isotope effects with ε values of 14.0‰ (KIE = 0.9862) and 36.1‰ (KIE = 0.9651), respectively. The observed inverse isotope effect in δ(15)N(β) is consistent with reversible binding of the first NO in the P450nor reaction mechanism. In contrast to the constant SP observed during NO reduction in microbial cultures, the site preference measured for purified H. capsulatum P450nor was not constant, increasing from ∼ 15‰ to ∼ 29‰ during the course of the reaction. This indicates that SP for microbial cultures can vary depending on the growth conditions, which may complicate source tracing during microbial denitrification.

  17. Gross nitrous oxide production drives net nitrous oxide fluxes across a salt marsh landscape.

    PubMed

    Yang, Wendy H; Silver, Whendee L

    2016-06-01

    Sea level rise will change inundation regimes in salt marshes, altering redox dynamics that control nitrification - a potential source of the potent greenhouse gas, nitrous oxide (N2 O) - and denitrification, a major nitrogen (N) loss pathway in coastal ecosystems and both a source and sink of N2 O. Measurements of net N2 O fluxes alone yield little insight into the different effects of redox conditions on N2 O production and consumption. We used in situ measurements of gross N2 O fluxes across a salt marsh elevation gradient to determine how soil N2 O emissions in coastal ecosystems may respond to future sea level rise. Soil redox declined as marsh elevation decreased, with lower soil nitrate and higher ferrous iron in the low marsh compared to the mid and high marshes (P < 0.001 for both). In addition, soil oxygen concentrations were lower in the low and mid-marshes relative to the high marsh (P < 0.001). Net N2 O fluxes differed significantly among marsh zones (P = 0.009), averaging 9.8 ± 5.4 μg N m(-2)  h(-1) , -2.2 ± 0.9 μg N m(-2)  h(-1) , and 0.67 ± 0.57 μg N m(-2)  h(-1) in the low, mid, and high marshes, respectively. Both net N2 O release and uptake were observed in the low and high marshes, but the mid-marsh was consistently a net N2 O sink. Gross N2 O production was highest in the low marsh and lowest in the mid-marsh (P = 0.02), whereas gross N2 O consumption did not differ among marsh zones. Thus, variability in gross N2 O production rates drove the differences in net N2 O flux among marsh zones. Our results suggest that future studies should focus on elucidating controls on the processes producing, rather than consuming, N2 O in salt marshes to improve our predictions of changes in net N2 O fluxes caused by future sea level rise.

  18. Catalytic Decomposition of N2O at Low Temperature by Reduced Cobalt Oxides.

    PubMed

    Eom, Won-Hyun; Ayoub, Muhammad; Yoo, Kyung-Seun

    2016-05-01

    Various forms of cobalt oxide (Co3O4 and C0203) were subsequently prepared and tested for decomposition of N2O at low temperature in a fix bed differential reactor at steady state conditions. These different types of oxides were prepared by precipitation method (PM) and by calcination of commercially available CoCO3. Commercially available cobalt oxides C03O4 and C02O3 were also tested for N2O decomposition at different temperatures. All types of prepared and commercially available cobalt oxide were found inactive for N2O decomposition in the presence of oxygen at temperature less than 300 degrees C. Similar unsatisfactory results were found at low temperature N2O decomposition after impregnation of alkali metal (10% Na) and alkaline earth metal (10% Ba) over Co3O4. These catalysts were then reduced under reduction media (H2 gas). It was found that after reduction cobalt oxide catalysts became active for N2O decomposition for short time in the presence of oxygen at low temperature. The reduced form of Co3O4 catalyst showed enormous efficiency i.e., 98% at temperature (300 degrees C) under the same conditions. From results it seems that Co3O4 itself is not active for N2O decomposition but its reduced form is highly active for this reaction due to oxidation state change of C03O4 during reduction process.

  19. Quantitative measurement of direct nitrous oxide emissions from microalgae cultivation.

    PubMed

    Fagerstone, Kelly D; Quinn, Jason C; Bradley, Thomas H; De Long, Susan K; Marchese, Anthony J

    2011-11-01

    Although numerous lifecycle assessments (LCA) of microalgae-based biofuels have suggested net reductions of greenhouse gas emissions, limited experimental data exist on direct emissions from microalgae cultivation systems. For example, nitrous oxide (N(2)O) is a potent greenhouse gas that has been detected from microalgae cultivation. However, little quantitative experimental data exist on direct N(2)O emissions from microalgae cultivation, which has inhibited LCA performed to date. In this study, microalgae species Nannochloropsis salina was cultivated with diurnal light-dark cycling using a nitrate nitrogen source. Gaseous N(2)O emissions were quantitatively measured using Fourier transform infrared spectrometry. Under a nitrogen headspace (photobioreactor simulation), the reactors exhibited elevated N(2)O emissions during dark periods, and reduced N(2)O emissions during light periods. Under air headspace conditions (open pond simulation), N(2)O emissions were negligible during both light and dark periods. Results show that N(2)O production was induced by anoxic conditions when nitrate was present, suggesting that N(2)O was produced by denitrifying bacteria within the culture. The presence of denitrifying bacteria was verified through PCR-based detection of norB genes and antibiotic treatments, the latter of which substantially reduced N(2)O emissions. Application of these results to LCA and strategies for growth management to reduce N(2)O emissions are discussed.

  20. Nitrous oxide emissions from smooth bromegrass pasture under nitrogen fertilizer and bovine urine application in eastern Nebraska

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) is a greenhouse gas primarily produced in soils by denitrifying and nitrifying organisms. In terms of global warming potential (GWP), N2O has 310 times the GWP of carbon dioxide (CO2). Atmospheric N2O concentrations have increased by 18% since the industrial revolution with agr...

  1. On-site wood-chip bioreactors could reduce indirect nitrous oxide emissions from tile drain waters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Indirect nitrous oxide (N2O) emissions originating from nitrate-laden agricultural drainage waters represent approximately 21% of total N2O emissions in the USA. Typical strategies to mitigate indirect N2O emissions are either improving fertilization methods or on-site treatment of drainage water. R...

  2. Mitigating Sources of Indirect Nitrous Oxide Emissions from Tile Drain by On-Site Wood-Chip Bioreactors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Indirect nitrous oxide (N2O) emissions originating from nitrate-laden agricultural drainage waters represent a substantial fraction of total N2O emissions in the USA. Typical strategies to mitigate indirect N2O emissions are either improving fertilization methods or on-site treatment of drainage wat...

  3. Nitrification gene ratio and free ammonia explain nitrite and nitrous oxide production in urea-amended soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Substantial efforts have been made to characterize soil nitrous oxide (N2O) emissions following N fertilizer addition. While nitrite (NO2-) is a central regulator of N2O production, NO2- and N2O responses to nitrogen (N) fertilizer amendments still cannot be readily predicted. Our objective was to...

  4. Nitrous oxide emissions and herbage accumulation in smooth bromegrass pastures with nitrogen fertilizer and ruminant urine application

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural soils contribute significantly to nitrous oxide (N2O) emissions, but little data is available on N2O emissions from smooth bromegrass (Bromus inermis Leyss.) pastures. This study evaluated soil N2O emissions and herbage accumulation from smooth bromegrass pasture in eastern Nebraska, US...

  5. Detecting nitrous oxide reductase (nosZ) genes in soil metagenomes: method development and implications for the nitrogen cycle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Incomplete denitrification in soils represents a major source of nitrous oxide (N2O), a potent greenhouse gas. The key enzyme for mitigating N2O emissions is NosZ, which catalyzes N2O reduction to N2 and is generally attributed to denitrifiers. We recently described an “atypical” functional NosZ enz...

  6. Decomposition of nitrous oxide on pillared clays.

    PubMed

    De Stefanis, A; Dondi, M; Perez, G; Tomlinson, A A

    2000-10-01

    Alumina-pillared smectites have been found to abate nitrous oxide in the presence of methane. The results indicate that the yield of the reaction (N20 --> N2 + (1/2)O2) increases when pillared clays are exchanged with transition metals, single-pass conversion rates of >70% being attainable. In particular, when double exchanged (calcium and subsequently copper) alumina pillared montmorillonite/beidellite is used as a catalyst, de-N2O activity reaches a maximum, which is maintained even after 4 h of work at a space velocity of 5.5 h(-1). A mechanism for the reaction is suggested, which implies that N2O is first adsorbed by the catalyst and then decomposes through two different paths: catalyst oxidation and catalyst reduction. Such a redox process explains the kinetic data.

  7. Nitrous oxide sources and sinks in coastal aquifers and coupled estuarine receiving waters.

    PubMed

    LaMontagne, Michael G; Duran, Robert; Valiela, Ivan

    2003-06-20

    Sources and sinks of the atmospherically reactive gas nitrous oxide (N(2)O) were determined in the heavily nutrient loaded Childs River in Cape Cod, MA. Surface waters were supersaturated and bottom waters were depleted with N(2)O throughout the system. In apparent septic effluent plumes, N(2)O concentrations reached 3 orders of magnitude above atmospheric equilibrium. Because nitrate and N(2)O concentrations correlated in groundwater entering the estuary, septic tank effluent appeared responsible for the supersaturated concentrations of N(2)O in surface waters. A hyperbolic function fit nitrate and N(2)O concentrations in the water column of the estuary with a maximum supersaturation of approximately 60 nM. From surface water supersaturation we predicted a release of 480 nmol N(2)O m(-2) h(-1) to the atmosphere in the summer. Property plots of salinity vs. bottom-water N(2)O suggested a benthic sink of N(2)O. Consistent with this trend, sediments consumed rather than released N(2)O in most flux measurements. Nutrient loading did not directly alter benthic N(2)O flux, potentially because stratification limited exposure of sediments to nitrate-rich surface waters, but macroalgal cover increased benthic N(2)O consumption. Sediment N(2)O consumption averaged 111 nmol N(2)O m(-2) h(-1) and correlated with oxygen uptake. Losses from the system to the atmosphere and sediments exceeded inputs of N(2)O contaminated groundwater, which suggests missing N(2)O sources.

  8. 'Rhizotraits' for mitigation of soil nitrous oxide emission

    NASA Astrophysics Data System (ADS)

    Baggs, Elizabeth; Morley, Nick; Villada, Antia; Bardgett, Richard; Shaw, Liz

    2014-05-01

    The role of plant traits in driving components of the N cycle is poorly characterised. Here we demonstrate plant-derived C to regulate nitrous oxide (N2O) production and reduction in the rhizosphere. We use isotope (13C, 14C and 15N) techniques and a new isotope-FISH-FACS approach to verify (i) the link between plant-C and activity of microbial nitrate reducers, (ii) uptake of C compounds into pseudomonads, (iii) the role of both composite rhizodeposits and individual compounds in regulating the magnitude of N2O emission, and (iv) their influence on the N2O:N2 product ratio. We examine the potential these relationships offer to use plants to manipulate the rhizosphere for reduction of N2O emissions and the possibility of characterising plant 'rhizotraits' that enhance reduction of N2O to N2.

  9. Nitrous oxide-induced hypothermia in the rat

    SciTech Connect

    Quock, R.M.; Panek, R.W.; Kouchich, F.J.; Rosenthal, M.A.

    1987-08-10

    Exposure of rats to high levels of nitrous oxide (N2O) in oxygen reduced body temperature in a concentration-related manner. The hypothermia was partly reversed by pretreatment with naloxone but not naltrexone. But in rats rendered tolerant to morphine by pellet implantation, exposure to 75% N2O/25% O2 evoked a marked hypothermia similar to that observed in morphine-naive animals. In another experiment, the hypothermic effect of chloral hydrate was also sensitive to antagonism by pretreatment with naloxone but not naltrexone. These observations lead the authors to suspect that N2O-induced hypothermia in rats is possibly not mediated by opiate receptors. The thermotropic activity of N2O may result from some non-opioid action of N2O. Its selective antagonism by naloxone (but not naltrexone) may be due to a unique non-opioid analeptic action of naloxone. 32 references, 4 figures.

  10. Effects of nitrogen application rate and a nitrification inhibitor dicyandiamide on ammonia oxidizers and N2O emissions in a grazed pasture soil.

    PubMed

    Dai, Yu; Di, Hong J; Cameron, Keith C; He, Ji-Zheng

    2013-11-01

    Ammonia oxidizers, including ammonia oxidizing bacteria (AOB) and ammonia oxidizing archaea (AOA) are important drivers of a key step of the nitrogen cycle - nitrification, which affects the production of the potent greenhouse gas, nitrous oxide (N2O). A field experiment was conducted to determine the effect of nitrogen application rates and the nitrification inhibitor dicyandiamide (DCD) on the abundance of AOB and AOA and on N2O emissions in a grazed pasture soil. Nitrogen (N) was applied at four different rates, with urea applied at 50 and 100 kg N ha(-1) and animal urine at 300 and 600 kg N ha(-1). DCD was applied to some of the N treatments at 10 kg ha(-1). The results showed that the AOB amoA gene copy numbers were greater than those of AOA. The highest ratio of the AOB to AOA amoA gene copy numbers was 106.6 which occurred in the urine-N 600 treatment. The AOB amoA gene copy numbers increased with increasing nitrogen application rates. DCD had a significant impact in reducing the AOB amoA gene copy numbers especially in the high nitrogen application rates. N2O emissions increased with the N application rates. DCD had the most significant effect in reducing the daily and total N2O emissions in the highest nitrogen application rate. The greatest reduction of total N2O emissions by DCD was 69% in the urine-N 600 treatment. The reduction in the N2O emission factor by DCD ranged from 58% to 83%. The N2O flux and NO3(-)-N concentrations were significantly correlated to the growth of AOB, rather than AOA. This study confirms the importance of AOB in nitrification and the effect of DCD in inhibiting AOB growth and in decreasing N2O emissions in grazed pasture soils under field conditions.

  11. Terrestrial and Aquatic Nitrous Oxide Emissions

    NASA Astrophysics Data System (ADS)

    Turner, Peter August

    Agriculture represents the largest source of anthropogenic nitrous oxide (N2O), a potent greenhouse gas and the dominant ozone depleting substance. Globally, the magnitude of this source is well constrained; however, large uncertainties remain at regional-scales where the development of scalable mitigation practices and policies are needed. Therefore, this thesis sought to: 1) Quantify the strength of N2O emissions linked to nitrate (NO3-) runoff and revise regional budgets accordingly; and, 2) Identify the underlying mechanisms that control terrestrial and aquatic emissions in order to help guide N2O mitigation practices. The data and analyses indicated that agricultural rivers in the U.S. Corn Belt are significant sources of N2O to the atmosphere. A large bias (9-fold) in the Intergovernmental Panel on Climate Change N2O emission accounting methodology associated with river emissions (EF5r) was identified. Using a novel gas equilibration technique, stream water N 2O :NO3- ratios followed a Michaelis-Menten type relation, reaching maximum values of 4.6-times ambient saturation. This response, attributed to environmental limits on in-situ production, implies that greater NO3- concentrations will have a progressively weaker effect on N2O emissions in the Mississippi River. However, based on future NO3- runoff scenarios, these analyses project that emissions could still increase by as much as 40%. Although innovative farming techniques, such as leguminous kura clover living mulches, could curtail NO3- losses and concurrent aquatic N2O emissions, experimental evidenced based on this research showed that they stimulate soil emissions. Although soils are the largest individual source, the magnitude and importance of emission "hotspots" remains unclear. Here, field-scale N2O emissions hotspots were identified using geospatial techniques and were consistently observed in low-lying areas prone to moisture and nutrient accumulation. These analyses indicated that targeted

  12. Ammonia and nitrous oxide emissions from a commercial broiler house

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Complex variation in gas emissions from animal facilities has been shown in recent research reports; uncertainties in these emission estimates are driving research activities concerning different animal species across the globe. Greenhouse gas (GHG, nitrous oxide (N2O) and carbon dioxide (CO2)) and ...

  13. Nitrous oxide activation by a cobalt(ii) complex for aldehyde oxidation under mild conditions.

    PubMed

    Corona, Teresa; Company, Anna

    2016-10-07

    Nitrous oxide (N2O) is a waste gas produced in many industrial processes with an important environmental impact. Thus, its application as an oxidant is highly desirable because it produces innocuous N2 as a by-product. In this work we report a new cobalt(ii) complex that reacts with N2O under mild conditions and the catalytic application of this system to carry out the oxidation of aldehydes.

  14. Nitrous Oxide Production in an Eastern Cornbelt Soil: Sources and Redox Range

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide derived from soils is a main contributor to the greenhouse gas effect and ozone layer depletion; however, sources and regulation are not clearly understood. This study was conducted to estimate magnitude and sources of nitrous oxide (N2O) production as affect by N source, soil water co...

  15. Global agriculture and nitrous oxide emissions

    NASA Astrophysics Data System (ADS)

    Reay, Dave S.; Davidson, Eric A.; Smith, Keith A.; Smith, Pete; Melillo, Jerry M.; Dentener, Frank; Crutzen, Paul J.

    2012-06-01

    Nitrous oxide (N2O) is an important anthropogenic greenhouse gas and agriculture represents its largest source. It is at the heart of debates over the efficacy of biofuels, the climate-forcing impact of population growth, and the extent to which mitigation of non-CO2 emissions can help avoid dangerous climate change. Here we examine some of the major debates surrounding estimation of agricultural N2O sources, and the challenges of projecting and mitigating emissions in coming decades. We find that current flux estimates -- using either top-down or bottom-up methods -- are reasonably consistent at the global scale, but that a dearth of direct measurements in some areas makes national and sub-national estimates highly uncertain. We also highlight key uncertainties in projected emissions and demonstrate the potential for dietary choice and supply-chain mitigation.

  16. Up: The rise of nitrous oxide abuse. An international survey of contemporary nitrous oxide use.

    PubMed

    Kaar, Stephen J; Ferris, Jason; Waldron, Jon; Devaney, Madonna; Ramsey, John; Winstock, Adam R

    2016-04-01

    In recent years the recreational use of inhaled nitrous oxide gas (N2O) is becoming increasingly popular, yet little is known about the characteristics of its users or the effects they experience. This paper presents original research from the 2014 Global Drug Survey (GDS) (n=74,864). GDS runs the largest survey of recreational drug use in the world. The findings confirm N2O as a very common drug of use, in particular in the UK and US (38.6% and 29.4% lifetime prevalence). In the UK N2O was reported to be the eighth most commonly used substance. N2O was generally consumed via gas-filled balloons, at festivals and clubs where use of other substances was common. The vast majority of users use infrequently, and their use is not associated with significant harm. However, there appears to be a subpopulation of heavy users who may be using in a dependent pattern. Analysis of last year N2O users (n=4883), confirms that N2O is associated with hallucinations and confusion (which may be the desired effects) and persistent numbness and accidental injury (27.8%, 23.9%, 4.3% and 1.2% of last year users, respectively). Accidental injury is associated with the highest number of 'hits' per session, suggesting a dose-response relationship. The presence of significant harm is discussed in the light of public education on the risks of N2O use and harm-reduction strategies appropriate to N2O use. Further work needs to be completed to confirm the presence of persistent neurological symptoms in recreational users.

  17. Sensory experience induced by nitrous oxide analgesia.

    PubMed Central

    Kaufman, E.; Galili, D.; Furer, R.; Steiner, J.

    1990-01-01

    Preliminary findings on a group of 15 dental patients, treated with nitrous oxide indicated frequent occurrence of several, well-defined sensory experiences related to various modalities. A subsequent controlled experiment carried out on 44 volunteers, inhaling a 35% N2O + 65% O2 sedative gas-mixture as well as O2 alone in two different sessions confirmed a large variety of sensations not related to external stimuli. Taste and/or odor and thermal sensations were often reported as well as changes in auditory or visual perception of the environment in addition to reports of general heaviness, relaxation or tingling. PMID:2097907

  18. N2O production rate of an enriched ammonia-oxidising bacteria culture exponentially correlates to its ammonia oxidation rate.

    PubMed

    Law, Yingyu; Ni, Bing-Jie; Lant, Paul; Yuan, Zhiguo

    2012-06-15

    The relationship between the ammonia oxidation rate (AOR) and nitrous oxide production rate (N(2)OR) of an enriched ammonia-oxidising bacteria (AOB) culture was investigated. The AOB culture was enriched in a nitritation system fed with synthetic anaerobic digester liquor. The AOR was controlled by adjusting the dissolved oxygen (DO) and pH levels and also by varying the initial ammonium (NH(4)(+)) concentration in batch experiments. Tests were also performed directly on the parent reactor where a stepwise decrease/increase in DO was implemented to alter AOR. The experimental data indicated a clear exponential relationship between the biomass specific N(2)OR and AOR. Four metabolic models were used to analyse the experimental data. The metabolic model formulated based on aerobic N(2)O production from the decomposition of nitrosyl radical (NOH) predicted the exponential correlation observed experimentally. The experimental data could not be reproduced by models developed on the basis of N(2)O production through nitrite (NO(2)(-)) and nitric oxide (NO) reduction by AOB.

  19. SIMULATION OF NITROUS OXIDE EMISSIONS FROM DAIRY FARMS TO ASSESS GREENHOUSE GAS REDUCTION STRATEGIES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Farming practices can have a large impact on the net emission of greenhouse gases including carbon dioxide, methane, and nitrous oxide (N**2O). The primary sources of N**2O from dairy farms are nitrification and denitrification processes in soil, with smaller contributions from manure storage and ba...

  20. Nitrous Oxide Emissions from a Large, Impounded River: The Ohio River

    EPA Science Inventory

    Models suggest that microbial activity in streams and rivers is a globally significant source of anthropogenic nitrous oxide (N2O), a potent greenhouse gas and the leading cause of stratospheric ozone destruction. However, model estimates of N2O emissions are poorly constrained ...

  1. A geostatistical approach to identify and mitigate agricultural nitrous oxide emission hotspots

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Anthropogenic emissions of nitrous oxide (N2O), a trace gas with severe environmental costs, are greatest from agricultural soils amended with nitrogen (N) fertilizer. However, accurate N2O emission estimates at fine spatial scales are made difficult by their high variability, which represents a cr...

  2. Microbial inoculants as tools for reducing nitrous oxide emissions from soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Over the past few decades, emissions of nitrous oxide (N2O) have increased worldwide due to several factors, including increases in cultivated crop area, use of synthetic nitrogen fertilizers, and livestock production. New management tools are needed to reduce N2O emissions from production agricultu...

  3. Application of microbial inoculants as tools for reducing nitrous oxide emissions from different nitrogen fertilizers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Emissions of nitrous oxide (N2O) are increasing due to several factors, including increased use of nitrogen fertilizers. New management tools are needed to reduce N2O emissions from production agriculture. One potential such tool is the use of microbial inoculants, which are increasingly being used ...

  4. Regional-scale controls on dissolved nitrous oxide in the Upper Mississippi River

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bottom-up estimates of riverine nitrous oxide (N2O) emissions developed by the Intergovernmental Panel on Climate Change (IPCC) assume a constant emission factor (EF5r) that predicts N2O production from anthropogenic nitrogen inputs. This relation ignores any direct stream water biochemical charact...

  5. Improved chamber systems for rapid, real-time nitrous oxide emissions from manure and soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) emission rates have traditionally been measured using non-flow-through, non-steady-state (NFT-NSS) chambers, which rely on measuring the increase in N2O concentration in the sealed chamber headspace over time. These flux measurements are very labor and time intensive, requiring ...

  6. Nitrous oxide emissions with enhanced efficiency nitrogen fertilizers in rainfed system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of enhanced efficiency nitrogen (N) fertilizers can increase crop N utilization and lead to lower emissions of the greenhouse gas nitrous oxide (N2O). To determine potential benefit of four enhanced efficiency fertilizers with rain-fed corn production in central Pennsylvania, USA, N2O emissi...

  7. Indirect nitrous oxide emissions from streams within the US Corn Belt scale with stream order

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) is an important greenhouse gas and the primary stratospheric ozone depleting substance. Its deleterious effects on the environment have prompted appeals to regulate emissions from agriculture, which represents the primary source in the global N2O budget. Successful implementation...

  8. Nitrous oxide emissions from a golf course fairway and rough following application of different nitrogen fertilizers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) is a potent greenhouse gas that destroys stratospheric ozone. There is limited research of golf course N2O emission and the effects of frequent fertilization and irrigation. Three enhanced efficiency nitrogen fertilizers (EENFs) were applied to a Colorado golf course fairway and ...

  9. Modeled nitrous oxide emissions from corn fields in Iowa based on county level data

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The US Corn Belt area has the capacity to generate high nitrous oxide (N2O) emissions due to medium to high annual precipitation, medium to heavy textured soils rich in organic matter, and high nitrogen (N) application rates. The purpose of this work was to estimate field N2O emissions from cornfiel...

  10. Controls on nitrous oxide production and consumption in reservoirs of the Ohio River Basin

    EPA Science Inventory

    Aquatic ecosystems are a globally significant source of nitrous oxide (N2O), a potent greenhouse gas, but estimates are largely based on studies conducted in streams and rivers with relatively less known about N2O dynamics in lakes and reservoirs. Due to long water residence tim...

  11. Comparing Nitrous Oxide Emissions from Three Residential Landscapes under Different Management Schemes Following Natural Rainfall Events

    EPA Science Inventory

    Cultural lawn management practices that produce aesthetically appealing landscapes may also create environmental conditions that stimulate soil nitrous oxide (N2O) emissions. The purpose of this study is to investigate the effects of lawn management practices on N2O fluxes from ...

  12. Nitrite-Driven Nitrous Oxide Production Under Aerobic Soil Conditions: Kinetics and Biochemical Controls

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrite (NO2-) can accumulate during nitrification in soil following fertilizer application. While the role of NO2- as a substrate regulating nitrous oxide (N2O) production is recognized, kinetic data are not available that allow for estimating N2O production or soil-to-atmosphere fluxes as a functi...

  13. Key factors, Soil N Processes, and nitrite accumulation affecting nitrous oxide emissions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A better understanding of the key factors affecting nitrous oxide (N2O) emission and potential mitigation strategies is essential for sustainable agriculture. The objective of this study was to examine the important factors affecting N2O emissions, soil processes involved, and potential mitigation s...

  14. Nitrous Oxide Explosive Hazards

    DTIC Science & Technology

    2008-05-01

    may be the only way to ensure large N2O system safety. Prior hazard and monopropellant decomposition studies largely indicated that N2O was...difficult to initiate into dangerous monopropellant decompositions. Based on prior studies and use of N2O for decades in dental practice without serious... monopropellant decomposition studies largely indicated that N2O was difficult to initiate into dangerous monopropellant decompositions. Based on prior

  15. A comprehensive study on the oxidation of 4H-SiC in diluted N2O ambient

    NASA Astrophysics Data System (ADS)

    Tseng, Yuan-Hung; Wu, Tsung-Han; Tsui, Bing-Yue; Yen, Cheng-Tyng; Hung, Chien-Chung; Lee, Chwan-Ying

    2017-04-01

    The oxidation mechanism of 4H-SiC in diluted N2O ambient was studied at various temperatures, N2O flow rates, and N2/N2O flow ratios. The collision partner, N2 in this study, plays crucial roles in determining the oxidation rate and N-incorporation. According to the proposed oxidation mechanism, lowering the interface state density at lower oxidation temperatures is possible with a high-efficiency collision partner.

  16. Nitrous Oxide: A Greenhouse Gas That is Also an Ozone Layer Depleting Gas

    NASA Astrophysics Data System (ADS)

    Ravishankara, A. R.

    2015-12-01

    Nitrous oxide, N2O, is the major source of nitrogen oxides in the stratosphere, where these oxides playa critical roles in ozone layer depletion by itself and moderating ozone layer depletion by chlorinated chemicals. Thus N2O plays a complex role in the stratosphere. Nitrous oxide is also a greenhouse gas and it contributes to the radiative forcing of climate. Indeed, it is considered the third most important greenhouse gas next to carbon dioxide and methane. This dual role of nitrous oxide makes it an interesting gas for the atmosphere- it bridges the issue of ozone layer depletion and climate change. Nitrous oxide has both natural and anthropogenic sources. Therefore, one needs to consider this important distinction between natural and anthropogenic sources as well as its role in two related but separate environmental issues. Further, the sources of nitrous oxide are varied and diffuse, which makes it difficult to quantify different sources. However, it is clear that a majority of anthropogenic nitrous oxide comes from food production (including agricultural and animal growth practices), an activity that is at the heart of human existence. Thus, limiting N2O emissions is not a simple task! I will briefly summarize our understanding of these roles of nitrous oxide in the earth's atmosphere and touch on the possible ways to limit N2O emissions.

  17. Modeling electron competition among nitrogen oxides reduction and N2O accumulation in denitrification.

    PubMed

    Pan, Yuting; Ni, Bing-Jie; Yuan, Zhiguo

    2013-10-01

    Competition for electrons among different steps of denitrification has previously been shown to occur, and to play an important role in the accumulation and emission of N2O in wastewater treatment. However, this electron competition is not recognized in the current denitrification models, limiting their ability to predict N2O accumulation during denitrification. In this work, a new denitrification model is developed for wastewater treatment processes. It describes electron competition among the four steps of denitrification, through modeling the carbon oxidation and nitrogen reduction processes separately, in contrast to the existing models that directly couple these two types of processes. Electron carriers are introduced to link carbon oxidation, which donates electrons to carriers, and nitrogen oxides reduction, which receives electrons from these carriers. The relative ability of each denitrification step to compete for electrons is modeled through the use of different affinity constants with reduced carriers. Model calibration and validation results demonstrate that the developed model is able to reasonably describe the nitrate, nitrite, and N2O reduction rates of a methanol-utilizing denitrifying culture under various carbon and nitrogen oxides supplying conditions. The model proposed, while subject to further validation, is expected to enhance our ability to predict N2O accumulation in denitrification.

  18. Nitrous oxide and perioperative outcomes.

    PubMed

    Ko, Hanjo; Kaye, Alan David; Urman, Richard D

    2014-06-01

    There is emerging evidence related to the effects of nitrous oxide on important perioperative patient outcomes. Proposed mechanisms include metabolic effects linked to elevated homocysteine levels and endothelial dysfunction, inhibition of deoxyribonucleic acid and protein formation, and depression of chemotactic migration by monocytes. Newer large studies point to possible risks associated with the use of nitrous oxide, although data are often equivocal and inconclusive. Cardiovascular outcomes such as stroke or myocardial infarction were shown to be unchanged in previous studies, but the more recent Evaluation of Nitrous Oxide in the Gas Mixture for Anesthesia I trial shows possible associations between nitrous oxide and increased cardiovascular and pulmonary complications. There are also possible effects on postoperative wound infections and neuropsychological function, although the multifactorial nature of these complications should be considered. Teratogenicity linked to nitrous oxide use has not been firmly established. The use of nitrous oxide for routine anesthetic care may be associated with significant costs if complications such as nausea, vomiting, and wound infections are taken into consideration. Overall, definitive data regarding the effect of nitrous oxide on major perioperative outcomes are lacking. There are ongoing prospective studies that may further elucidate its role. The use of nitrous oxide in daily practice should be individualized to each patient's medical conditions and risk factors.

  19. Stratospheric nitrous oxide distribution in the Southern Hemisphere

    NASA Technical Reports Server (NTRS)

    Podolske, J. R.; Loewenstein, M.; Strahan, S. E.; Chan, K. R.

    1989-01-01

    Nitrous oxide measurements were made in the Southern Hemisphere as part of the Airborne Antarctic Ozone Experiment in late winter and early spring 1987, covering the altitude range 14-21 km. This paper reports on N2O measurements made by the airborne tunable laser absorption spectrometer, which was flown onboard the NASA ER-2 aircraft. Average vertical N2O profiles at latitudes 72 deg S, 54 deg S, and 42 deg S are presented and compared, when possible, with equivalent summer profiles. Latitudinal gradients of N2O on isentropic surfaces are presented and discussed in terms of their implications about the inhibition of horizontal mixing near the polar vortex. Finally, a large-scale distribution of N2O for the region 72 deg S to 42 deg S latitude is presented.

  20. Nitrous Oxide as a Green Monopropellant for Small Satellites

    NASA Astrophysics Data System (ADS)

    Wallbank, J.; Sermon, P.; Baker, A.; Courtney, L.; Sambrook, R.

    2004-10-01

    Nitrous oxide (N2O), has been suggested as a green monopropellant for hydrazine replacement [1,2]. It has extremely low toxicity and has a higher theoretical specific impulse (ISP) than 90% hydrogen peroxide (HTP): N2O ISP(t)~206s, HTP ISP(t)~180s [3]. It has largely been overlooked though due to the difficulty involved in maintaining reproducible catalytic decomposition. The authors are developing N2O thruster technology to prove its viability as a monopropellant alternative to hydrazine. Towards this purpose the authors have developed a novel catalyst for the decomposition of N2O, that has high activity and is thermally stable in oxidising conditions. The catalyst is being engineered into a form to be used efficiently within the thruster housing. This paper reports on the development of this catalyst.

  1. Source Tracking of Nitrous Oxide using A Quantum Cascade ...

    EPA Pesticide Factsheets

    Nitrous oxide is an important greenhouse gas and ozone depleting substance. Nitrification and denitrification are two major biological pathways that are responsible for soil emissions of N2O. However, source tracking of in-situ or laboratory N2O production is still challenging to soil scientists. The objective of this study was to introduce the use of a new technology, quantum cascade laser (QCL) spectroscopy, which allows for significantly improved accuracy and precision to continuously measure real-time N2O for source tracking. This data provides important emission inventory information to air quality and atmospheric chemistry models. The task demonstrated that QCL spectroscopy can measure the flux of nitrous oxide at ambient and well as elevated concentrations in real time. The fractionation of the nitrous oxide produced by microbial processing of nitrate can be measured and characterized as isotopic signatures related to the nitrifying or denitrifying state of the microbial communities. This has important implications for monitoring trace gases in the atmosphere. The data produced by this system will provide clients including the air quality and climate change communities with needed information on the sources and strengths of N2O emissions for modeling and research into mitigation strategies to reduce overall GHG emissions in agricultural systems.

  2. Nitrous oxide emission hotspots from organic soils in Europe

    NASA Astrophysics Data System (ADS)

    Leppelt, T.; Dechow, R.; Gebbert, S.; Freibauer, A.; Lohila, A.; Augustin, J.; Drösler, M.; Fiedler, S.; Glatzel, S.; Höper, H.; Järveoja, J.; Lærke, P. E.; Maljanen, M.; Mander, Ü.; Mäkiranta, P.; Minkkinen, K.; Ojanen, P.; Regina, K.; Strömgren, M.

    2014-06-01

    Organic soils are a main source of direct nitrous oxide (N2O) emissions, an important greenhouse gas (GHG). Observed N2O emissions from organic soils are highly variable in space and time which causes high uncertainties in national emission inventories. Those uncertainties could be reduced when relating the upscaling process to a priori identified key drivers by using available N2O observations from plot scale in empirical approaches. We used the empirical fuzzy modelling approach MODE to identify main drivers for N2O and utilize them to predict the spatial emission pattern of European organic soils. We conducted a meta study with a total amount of 659 annual N2O measurements which was used to derive separate models for different land use types. We applied our models to available, spatial explicit input driver maps to upscale N2O emissions on European level and compared the inventory with recently published IPCC emission factors. The final statistical models explained up to 60% of the N2O variance. Our study results showed that cropland and grasslands emitted the highest N2O fluxes 0.98 ± 1.08 and 0.58 ± 1.03 g N2O-N m-2 a-1, respectively. High fluxes from cropland sites were mainly controlled by low soil pH-value and deep drained groundwater tables. Grassland hotspot emissions were strongly related to high amount of N-fertilizer inputs and warmer winter temperatures. In contrast N2O fluxes from natural peatlands were predominantly low (0.07±0.27 g N2O-N m-2 a-1) and we found no relationship with the tested drivers. The total inventory for direct N2O emissions from organic soils in Europe amount up to 149.5 Gg N2O-N a-1, which included also fluxes from forest and peat extraction sites and exceeds the inventory calculated by IPCC emission factors of 87.4 Gg N2O-N a-1. N2O emissions from organic soils represent up to 13% of total European N2O emissions reported in the European Union (EU) greenhouse gas inventory of 2011 from only 7% of the EU area. Thereby the

  3. Health hazards and nitrous oxide: a time for reappraisal.

    PubMed

    Yagiela, J A

    1991-01-01

    Recent adoption by the American Conference of Governmental Industrial Hygienists of a Threshold Limit Value of 50 ppm for an 8-hour average exposure to nitrous oxide (N2O) increases the likelihood for its regulation by state and federal occupational health agencies. This review outlines current information on the health risks of N2O inhalation to provide a basis from which safe and reasonably attainable exposure limits can be proposed. Although N2O was for many years believed to have no toxicity other than that associated with its anesthetic action, bone marrow depression in patients administered N2O for extended periods of time and neurological abnormalities in health care workers who inhaled N2O recreationally have disproved this notion. Retrospective surveys of dental and medical personnel have also linked occupational exposure to N2O with a number of health problems and reproductive derangements. Nitrous oxide reacts with the reduced form of vitamin B12, thereby inhibiting the action of methionine synthase, an enzyme that indirectly supports methylation reactions and nucleic acid synthesis. Many, if not all, of the nonanesthetic-related adverse effects of N2O may be ascribed to this action. Animal and human studies indicate that the toxic effects of N2O are concentration- and time-dependent. It is suggested that a time-weighted average of 100 ppm for an 8-hour workday and/or a time-weighted average of 400 ppm per anesthetic administration would provide adequate protection of dental personnel and be achievable with existing pollution control methods.

  4. Nitrous oxide emissions from light duty vehicles

    NASA Astrophysics Data System (ADS)

    Graham, Lisa A.; Belisle, Sheri L.; Rieger, Paul

    Nitrous oxide (N 2O) emissions measurements were made on light duty gasoline and light duty diesel vehicles during chassis dynamometer testing conducted at the Environment Canada and California Air Resources Board vehicle emissions laboratories between 2001 and 2007. Per phase and composite FTP emission rates were measured. A subset of vehicles was also tested using other driving cycles to characterize emissions as a function of different driving conditions. Vehicles were both new (<6500 km) and in-use (6500-160,000 km) and were tested on low sulfur gasoline (<30 ppm) or low sulfur diesel (<300 ppm). Measurements from selected published studies were combined with these new measurements to give a test fleet of 467 vehicles meeting both US EPA and California criteria pollutant emissions standards between Tier 0 and Tier 2 Bin 3 or SULEV. Aggregate distance-based and fuel-based emission factors for N 2O are reported for each emission standard and for each of the different test cycles. Results show that the distinction between light duty automobile and light duty truck is not significant for any of the emission standards represented by the test fleet and the distinction between new and aged catalyst is significant for vehicles meeting all emission standards but Tier 2. This is likely due to the relatively low mileage accumulated by the Tier 2 vehicles in this study as compared to the durability requirement of the standard. The FTP composite N 2O emission factors for gasoline vehicles meeting emission standards more stringent than Tier 1 are substantially lower than those currently used by both Canada and the US for the 2005 inventories. N 2O emission factors from test cycles other than the FTP illustrate the variability of emission factors as a function of driving conditions. N 2O emission factors are shown to strongly correlate with NMHC/NMOG emission standards and less strongly with NO X and CO emission standards. A review of several published reports on the effect

  5. Modelling terrestrial nitrous oxide emissions and implications for climate feedback.

    PubMed

    Xu-Ri; Prentice, I Colin; Spahni, Renato; Niu, Hai Shan

    2012-10-01

    Ecosystem nitrous oxide (N2O) emissions respond to changes in climate and CO2 concentration as well as anthropogenic nitrogen (N) enhancements. Here, we aimed to quantify the responses of natural ecosystem N2O emissions to multiple environmental drivers using a process-based global vegetation model (DyN-LPJ). We checked that modelled annual N2O emissions from nonagricultural ecosystems could reproduce field measurements worldwide, and experimentally observed responses to step changes in environmental factors. We then simulated global N2O emissions throughout the 20th century and analysed the effects of environmental changes. The model reproduced well the global pattern of N2O emissions and the observed responses of N cycle components to changes in environmental factors. Simulated 20th century global decadal-average soil emissions were c. 8.2-9.5 Tg N yr(-1) (or 8.3-10.3 Tg N yr(-1) with N deposition). Warming and N deposition contributed 0.85±0.41 and 0.80±0.14 Tg N yr(-1), respectively, to an overall upward trend. Rising CO2 also contributed, in part, through a positive interaction with warming. The modelled temperature dependence of N2O emission (c. 1 Tg N yr(-1) K(-1)) implies a positive climate feedback which, over the lifetime of N2O (114 yr), could become as important as the climate-carbon cycle feedback caused by soil CO2 release.

  6. Nitrous oxide and methane emissions from cryptogamic covers.

    PubMed

    Lenhart, Katharina; Weber, Bettina; Elbert, Wolfgang; Steinkamp, Jörg; Clough, Tim; Crutzen, Paul; Pöschl, Ulrich; Keppler, Frank

    2015-10-01

    Cryptogamic covers, which comprise some of the oldest forms of terrestrial life on Earth (Lenton & Huntingford, ), have recently been found to fix large amounts of nitrogen and carbon dioxide from the atmosphere (Elbert et al., ). Here we show that they are also greenhouse gas sources with large nitrous oxide (N2 O) and small methane (CH4 ) emissions. Whilst N2 O emission rates varied with temperature, humidity, and N deposition, an almost constant ratio with respect to respiratory CO2 emissions was observed for numerous lichens and bryophytes. We employed this ratio together with respiration data to calculate global and regional N2 O emissions. If our laboratory measurements are typical for lichens and bryophytes living on ground and plant surfaces and scaled on a global basis, we estimate a N2 O source strength of 0.32-0.59 Tg year(-1) for the global N2 O emissions from cryptogamic covers. Thus, our emission estimate might account for 4-9% of the global N2 O budget from natural terrestrial sources. In a wide range of arid and forested regions, cryptogamic covers appear to be the dominant source of N2 O. We suggest that greenhouse gas emissions associated with this source might increase in the course of global change due to higher temperatures and enhanced nitrogen deposition.

  7. The δ15N and δ18O values of N2O produced during the co-oxidation of ammonia by methanotrophic bacteria

    USGS Publications Warehouse

    Mandernack, Kevin W.; Mills, Christopher T.; Johnson, Craig A.; Rahn, Thomas; Kinney, Chad

    2009-01-01

    via methanotrophic or autotrophic nitrifying bacteria can have very positive δ18ON2O values if the O2incorporated is previously enriched in 18O from high rates of respiration. Nitrous oxide was collected from various depths in soils overlying a coal-bed methane seep where methanotrophic bacteria are naturally enriched. In one sampling when soil methane concentrations were very high, the δ18OVSMOW values of the N2O were highly enriched (+ 50‰), consistent with our laboratory experiments. Thus, soils overlying methane seeps could provide an 18O-enriched source of atmospheric N2O.

  8. Nitrous oxide emissions from an aerobic granular sludge system treating low-strength ammonium wastewater.

    PubMed

    Gao, Mingming; Yang, Sen; Wang, Mingyu; Wang, Xin-Hua

    2016-11-01

    Aerobic granular sludge is a promising technology in wastewater treatment process. Its special microorganism structure could make the emissions of greenhouse gas nitrous oxide (N2O) more complicated. This study investigated the N2O emissions from a batch-fed aerobic granular sludge system during nitrification of low-strength synthetic ammonium wastewater. The N2O emission was 2.72 ± 0.52% of the oxidized ammonium during the whole anoxic-oxic sequencing batch reactor (SBR) cycle. Under nitrification batch test with sole ammonium substrate (50 mg N/L), N2O emission factor was 1.82% (N2ON/NH4(+)-Nox) and ammonia-oxidizing bacteria (AOB) was the responsible microorganism. The presence of high ammonium concentration (or high ammonium oxidation rate (AOR)) and accumulation of nitrite would lead to significant N2O emissions. AOB denitrification pathway was speculated to contribute more to the N2O emissions under nitrification conditions. While under simultaneous nitrification and denitrification condition with carbon source of 500 mg COD/L, the N2O emission factor increased to 2.76%. Both AOB and heterotrophic denitrifiers were responsible for N2O emission and heterotrophic denitrification enhances N2O emission. Step feeding of organic carbon source declined N2O emission factor to 1.60%, which underlined the role of storage substance consumption in N2O generation during denitrification.

  9. Nitrous Oxide Production in a Granule-based Partial Nitritation Reactor: A Model-based Evaluation.

    PubMed

    Peng, Lai; Sun, Jing; Liu, Yiwen; Dai, Xiaohu; Ni, Bing-Jie

    2017-04-03

    Sustainable wastewater treatment has been attracting increasing attentions over the past decades. However, the production of nitrous oxide (N2O), a potent GHG, from the energy-efficient granule-based autotrophic nitrogen removal is largely unknown. This study applied a previously established N2O model, which incorporated two N2O production pathways by ammonia-oxidizing bacteria (AOB) (AOB denitrification and the hydroxylamine (NH2OH) oxidation). The two-pathway model was used to describe N2O production from a granule-based partial nitritation (PN) reactor and provide insights into the N2O distribution inside granules. The model was evaluated by comparing simulation results with N2O monitoring profiles as well as isotopic measurement data from the PN reactor. The model demonstrated its good predictive ability against N2O dynamics and provided useful information about the shift of N2O production pathways inside granules for the first time. The simulation results indicated that the increase of oxygen concentration and granule size would significantly enhance N2O production. The results further revealed a linear relationship between N2O production and ammonia oxidation rate (AOR) (R(2) = 0.99) under the conditions of varying oxygen levels and granule diameters, suggesting that bulk oxygen and granule size may exert an indirect effect on N2O production by causing a change in AOR.

  10. Nitrous Oxide Production in a Granule-based Partial Nitritation Reactor: A Model-based Evaluation

    PubMed Central

    Peng, Lai; Sun, Jing; Liu, Yiwen; Dai, Xiaohu; Ni, Bing-Jie

    2017-01-01

    Sustainable wastewater treatment has been attracting increasing attentions over the past decades. However, the production of nitrous oxide (N2O), a potent GHG, from the energy-efficient granule-based autotrophic nitrogen removal is largely unknown. This study applied a previously established N2O model, which incorporated two N2O production pathways by ammonia-oxidizing bacteria (AOB) (AOB denitrification and the hydroxylamine (NH2OH) oxidation). The two-pathway model was used to describe N2O production from a granule-based partial nitritation (PN) reactor and provide insights into the N2O distribution inside granules. The model was evaluated by comparing simulation results with N2O monitoring profiles as well as isotopic measurement data from the PN reactor. The model demonstrated its good predictive ability against N2O dynamics and provided useful information about the shift of N2O production pathways inside granules for the first time. The simulation results indicated that the increase of oxygen concentration and granule size would significantly enhance N2O production. The results further revealed a linear relationship between N2O production and ammonia oxidation rate (AOR) (R2 = 0.99) under the conditions of varying oxygen levels and granule diameters, suggesting that bulk oxygen and granule size may exert an indirect effect on N2O production by causing a change in AOR. PMID:28367960

  11. Genetic engineering using fungal flavohemoglobin for constructing Pseudomonas stutzeri strain emitting less nitrous oxide.

    PubMed

    Takaya, Naoki; Shoun, Hirofumi

    2002-01-01

    Most denitrifiers produce the greenhouse gas nitrous oxide (N2O) due to insufficient anaerobiosis. We constructed a recombinant Pseudomonas stutzeri strain producing Fusarium oxysporum flavohemoglobin (fhb) and found that it emitted less N2O than the wild-type strain under aerobic and anaerobic conditions. The rate of N2 production was higher than in the wild-type strain after the depletion of oxygen in culture, suggesting that fhb enhanced the reduction of N2O to N2. The strain is the first recombinant bacterial denitrifier that reduces N2O production.

  12. Plant-mediated nitrous oxide emissions from beech (Fagus sylvatica) leaves.

    PubMed

    Pihlatie, Mari; Ambus, Per; Rinne, Janne; Pilegaard, Kim; Vesala, Timo

    2005-10-01

    Nitrous oxide (N2O) emission estimates from forest ecosystems are based currently on emission measurements using soil enclosures. Such enclosures exclude emissions via tall plants and trees and may therefore underestimate the whole-ecosystem N2O emissions. Here, we measured plant-mediated N2O emissions from the leaves of potted beech (Fagus sylvatica) seedlings after fertilizing the soil with 15N-labelled ammonium nitrate (15NH4(15)NO3), and after exposing the roots to elevated concentrations of N2O. Ammonium nitrate fertilization induced N2O + 15N2O emissions from beech leaves. Likewise, the foliage emitted N2O after beech roots were exposed to elevated concentrations of N2O. The average N2O emissions from the fertilization and the root exposure experiments were 0.4 and 2.0 microg N m(-2) leaf area h(-1), respectively. Higher than ambient atmospheric concentrations of N2O in the leaves of the forest trees indicate a potential for canopy N2O emissions in the forest. Our experiments demonstrate the existence of a previously overlooked pathway of N2O to the atmosphere in forest ecosystems, and bring about a need to investigate the magnitude of this phenomenon at larger scales.

  13. Pristine mangrove creek waters are a sink of nitrous oxide

    PubMed Central

    Maher, Damien T.; Sippo, James Z.; Tait, Douglas R.; Holloway, Ceylena; Santos, Isaac R.

    2016-01-01

    Nitrous oxide (N2O) is an important greenhouse gas, but large uncertainties remain in global budgets. Mangroves are thought to be a source of N2O to the atmosphere in spite of the limited available data. Here we report high resolution time series observations in pristine Australian mangroves along a broad latitudinal gradient to assess the potential role of mangroves in global N2O budgets. Surprisingly, five out of six creeks were under-saturated in dissolved N2O, demonstrating mangrove creek waters were a sink for atmospheric N2O. Air-water flux estimates showed an uptake of 1.52 ± 0.17 μmol m−2 d−1, while an independent mass balance revealed an average sink of 1.05 ± 0.59 μmol m−2 d−1. If these results can be upscaled to the global mangrove area, the N2O sink (~2.0 × 108 mol yr−1) would offset ~6% of the estimated global riverine N2O source. Our observations contrast previous estimates based on soil fluxes or mangrove waters influenced by upstream freshwater inputs. We suggest that the lack of available nitrogen in pristine mangroves favours N2O consumption. Widespread and growing coastal eutrophication may change mangrove waters from a sink to a source of N2O to the atmosphere, representing a positive feedback to climate change. PMID:27172603

  14. Potential Nitrous Oxide Emissions from Municipal Drinking Water

    NASA Astrophysics Data System (ADS)

    Anderson, D. E.; Thienelt, T.; Tindall, J.; McMahon, P.

    2005-12-01

    Nitrous oxide (N2O) is a potent greenhouse gas, having a global warming potential 280 times larger than carbon dioxide. Although the bulk of N2O emissions appear to be related to agricultural activity, various industrial and transportation related emissions exist as well. This study reports the discovery of a new and significant source of potential N2O emissions related to its presence in purified municipal water supplies worldwide. Multiple drinking water samples were obtained from 86 cities in the United States (US) and 44 cities in 16 countries in the Americas, Europe, Asia, and Africa. Samples ranged from 0.004 to 2μmol/L or the equivalent of 60% unsaturated to 200 times supersaturated with respect to ambient atmospheric concentration (320 ppb). Highest N2O contents were from southern US cities. Suspecting nitrification as the cause for the presence of N2O in drinking water, correlation statistics were calculated between N2O concentration and city size, geographical location, mean annual temperature, nitrate, and ammonia concentrations for the total population of samples as well as subsets based on country, water purification method, and raw water source (ground, surface, combination). The highest correlation (r=0.66, p<0.05, N=73) found was between latitude and N2O content for the subset group of large US cities using chloramines to purify water. Continuous year long sampling from a major US city indicated that variance in N2O content is remarkably low through the year within a water supply district. The annual US emission, based on this preliminary analysis, is 8x106 moles or 3.5X108 g N2O. Annual global emissions may be five times larger.

  15. Pristine mangrove creek waters are a sink of nitrous oxide

    NASA Astrophysics Data System (ADS)

    Maher, Damien T.; Sippo, James Z.; Tait, Douglas R.; Holloway, Ceylena; Santos, Isaac R.

    2016-05-01

    Nitrous oxide (N2O) is an important greenhouse gas, but large uncertainties remain in global budgets. Mangroves are thought to be a source of N2O to the atmosphere in spite of the limited available data. Here we report high resolution time series observations in pristine Australian mangroves along a broad latitudinal gradient to assess the potential role of mangroves in global N2O budgets. Surprisingly, five out of six creeks were under-saturated in dissolved N2O, demonstrating mangrove creek waters were a sink for atmospheric N2O. Air-water flux estimates showed an uptake of 1.52 ± 0.17 μmol m‑2 d‑1, while an independent mass balance revealed an average sink of 1.05 ± 0.59 μmol m‑2 d‑1. If these results can be upscaled to the global mangrove area, the N2O sink (~2.0 × 108 mol yr‑1) would offset ~6% of the estimated global riverine N2O source. Our observations contrast previous estimates based on soil fluxes or mangrove waters influenced by upstream freshwater inputs. We suggest that the lack of available nitrogen in pristine mangroves favours N2O consumption. Widespread and growing coastal eutrophication may change mangrove waters from a sink to a source of N2O to the atmosphere, representing a positive feedback to climate change.

  16. Genetic and Environmental Controls on Nitrous Oxide Accumulation in Lakes

    PubMed Central

    Saarenheimo, Jatta; Rissanen, Antti J.; Arvola, Lauri; Nykänen, Hannu; Lehmann, Moritz F.; Tiirola, Marja

    2015-01-01

    We studied potential links between environmental factors, nitrous oxide (N2O) accumulation, and genetic indicators of nitrite and N2O reducing bacteria in 12 boreal lakes. Denitrifying bacteria were investigated by quantifying genes encoding nitrite and N2O reductases (nirS/nirK and nosZ, respectively, including the two phylogenetically distinct clades nosZI and nosZII) in lake sediments. Summertime N2O accumulation and hypolimnetic nitrate concentrations were positively correlated both at the inter-lake scale and within a depth transect of an individual lake (Lake Vanajavesi). The variability in the individual nirS, nirK, nosZI, and nosZII gene abundances was high (up to tenfold) among the lakes, which allowed us to study the expected links between the ecosystem’s nir-vs-nos gene inventories and N2O accumulation. Inter-lake variation in N2O accumulation was indeed connected to the relative abundance of nitrite versus N2O reductase genes, i.e. the (nirS+nirK)/nosZI gene ratio. In addition, the ratios of (nirS+nirK)/nosZI at the inter-lake scale and (nirS+nirK)/nosZI+II within Lake Vanajavesi correlated positively with nitrate availability. The results suggest that ambient nitrate concentration can be an important modulator of the N2O accumulation in lake ecosystems, either directly by increasing the overall rate of denitrification or indirectly by controlling the balance of nitrite versus N2O reductase carrying organisms. PMID:25756328

  17. Understanding the sources and mitigation potential of nitrous oxide in agriculture

    NASA Astrophysics Data System (ADS)

    Horwath, W. R.; Zhu, X.; Doane, T. A.; Burger, M.

    2014-12-01

    More than half of the global warming potential of GHG emissions from agriculture is attributed to nitrous oxide (N2O).. Many factors control the production and release of N2O from soils. In addition to fertilizer N, soil N, moisture and carbon availability control N2O emissions. In addition, a previously overlooked factor, iron, was recently found to be the most significant factor influencing N2O production. Controlled by soil and management factors, N2O production is attributed to multiple pathways, including ammonia oxidation (AO), denitrification, and abiotic chemical reactions. Ammonia oxidation or nitrifier activity N2O production, is a well known pathway, but it significance to total N2O production is also highly debated and soil conditions influencing its production are poorly understood. Studies in a variety of crops in California strongly suggest that this pathway contributes substantially to N2O emissions. It is well established that denitrification primarily occurs under O2- limiting conditions, while N2O produced from AO is also influenced by soil O2 content, with maximum production occurring at low O2 levels (~0.5%). Since emission of N2O can arise from both AO and denitrification activities at low O2 concentrations, it is difficult to discern the importance of each pathway under various soil conditions and management. Furthermore, both the N form and concentration are determinants of nitrifier N2O production. The nitrifier denitrification pathway has been shown to dominate over nitrifier nitrification and nitrification coupled denitrification pathways. Irrigation, rainfall, and fertilization events stimulate microbial activity, including AO and denitrification that produces N2O and although limited, these events contribute to the majority of annual emissions. This uncertainty and complexity surrounding N2O production pathways has hampered the development of practices to reduce N2O emissions. As agricultural production intensifies in developing

  18. Nitrous Oxide Cycling and its Isotopic Signatures in South West Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Mullungal, M.; Van Hale, R.; Frew, R. D.; Law, C. S.

    2013-12-01

    Nitrous oxide (N2O) is a significant greenhouse gas and is also involved in ozone depletion. The contribution of N2O to both these processes is expected to increase this century. The ocean contributes about 30% to the atmospheric N2O budget so there is strong interest in the oceanic N2O cycle. In the ocean N2O is produced via a number of different processes (e.g. bacterial nitrification, and denitrification). While coastal regions are well-studied there are limited data available for open ocean N2O especially in the Southern Ocean, with few studies of the relative contribution of different bacterial processes. Here we apply new stable isotope techniques and present a detailed overview of the distribution and fate of dissolved nitrous oxide from sampling sites in the southwest Pacific Ocean near New Zealand. Samples for nitrous oxide and nutrients were collected along the depth profiles from two biophysical mooring stations (subtropical and sub- Antarctic), four Geotraces stations (GP13, subtropical Pacific) and two bloom voyage stations in the subtropical front and subtropical pacific waters. The N2O saturation ranged from near equilibrium with air at the surface to a maximum value in the oxygen minimum zone. Thus the surface water masses are not a significant sink or atmospheric source for N2O .Multi-isotope characterization of N2O including d15Nbulk, d18O, d15Nα and its site preference (SP, the difference between d15Nα and d15Nβ)indicates that nitrification is the primary process responsible for nitrous oxide production in oxic waters whereas coupling between nitrification and denitrification may be an important mechanism for production in the oxygen minimum zone with a minor contribution by nitrification.

  19. The Impact of Kura Clover Living Mulch on Nitrous Oxide Emissions in a Corn/Soybean System

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) is a potent greenhouse gas and the dominant ozone depleting substance. Produced primarily in agricultural soils, efforts to reduce N2O emissions are underway, but mitigation results thus far have been inconsistent. The leguminous perennial kura clover (Trifolium ambiguum M. Bie...

  20. Source Tracking of Nitrous Oxide using A Quantum Cascade Laser System in the Field and Laboratory Environments

    EPA Science Inventory

    Nitrous oxide is an important greenhouse gas and ozone depleting substance. Nitrification and denitrification are two major biological pathways that are responsible for soil emissions of N2O. However, source tracking of in-situ or laboratory N2O production is still challenging to...

  1. Advances in Understanding the Actions of Nitrous Oxide

    PubMed Central

    Emmanouil, Dimitris E; Quock, Raymond M

    2007-01-01

    Nitrous oxide (N2O) has been used for well over 150 years in clinical dentistry for its analgesic and anxiolytic properties. This small and simple inorganic chemical molecule has indisputable effects of analgesia, anxiolysis, and anesthesia that are of great clinical interest. Recent studies have helped to clarify the analgesic mechanisms of N2O, but the mechanisms involved in its anxiolytic and anesthetic actions remain less clear. Findings to date indicate that the analgesic effect of N2O is opioid in nature, and, like morphine, may involve a myriad of neuromodulators in the spinal cord. The anxiolytic effect of N2O, on the other hand, resembles that of benzodiazepines and may be initiated at selected subunits of the γ-aminobutyric acid type A (GABAA) receptor. Similarly, the anesthetic effect of N2O may involve actions at GABAA receptors and possibly at N-methyl-D-aspartate receptors as well. This article reviews the latest information on the proposed modes of action for these clinicaleffects of N2O. PMID:17352529

  2. Nitrogen limitation of nitrous oxide fluxes in the tropical Andes

    NASA Astrophysics Data System (ADS)

    Teh, Y.; Diem, T.; Morley, N.; Baggs, E.

    2013-12-01

    Montane Peruvian ecosystems are a regional atmospheric source of nitrous oxide (N2O) releasing at least 0.80 × 0.44 kg N ha-1 a-1. Field and laboratory experiments across a 3000 m elevation gradient in the Kosñipata Valley, Manu National Park, Peru indicate that nitrogen (N) availability, particularly nitrate (NO3-) content, are central to regulating N2O fluxes. Water-filled pore space (WFPS), soil moisture content, and carbon (C) availability play a secondary role in modulating fluxes. Field-based flux measurements indicate that N2O emissions and NO3- availability were inversely proportional with altitude, with lower elevation ecosystems (premontane forest, lower montane forest) emitting significantly more N2O and containing more NO3- than higher elevation ones (upper montane forest, montane grasslands). In lower elevation ecosystems, where NO3- was more abundant, N2O fluxes were influenced by WFPS, soil moisture, and to lesser extent by C mineralization rates. In contrast, in higher elevation ecosystems, WFPS and soil moisture content played little or no role in modulating fluxes, and N2O fluxes appeared to be more strongly driven by N availability.

  3. Simulating N2O emissions in different tillage systems of irrigated corn using RZ-Shaw model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) is potent greenhouse gas (GHG) and agriculture is a global source of N2O emissions from soil fertility management. Yet emissions vary by agronomic practices and environmental factors that govern soil moisture and temperature. Ecosystem models are important tools to estimate N2O e...

  4. Tracking short-term effects of 15N addition on N2O fluxes using FTIR spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Anthropogenic nitrogen (N) additions to soils have significantly increased atmospheric nitrous oxide (N2O) concentration, and advanced methods are needed to track the amount of applied N that is transformed to N2O in the field. Here, we present a method for continuous measurement of N2O isotopologu...

  5. N 2O oxidation of strained-Si/relaxed-SiGe heterostructure grown by UHVCVD

    NASA Astrophysics Data System (ADS)

    Tan, C. S.; Choi, W. K.; Bera, L. K.; Pey, K. L.; Antoniadis, D. A.; Fitzgerald, E. A.; Currie, M. T.; Maiti, C. K.

    2001-11-01

    Oxidation of strained-Si/relaxed-SiGe heterostructure grown by UHVCVD method using a rapid thermal processing technique in N 2O ambient is investigated. The electrical properties of the grown oxide have been characterized using a MOS structure. Hole confinement in the SiGe layer at low field is observed from the capacitance-voltage curve and this suggests that the strain in the initially strained Si epilayer is retained after oxidation. The experimental results are compared with simulation results obtained from a 1D Poisson solver. Dit and Qf/ q values are estimated to be 3×10 11 cm -2 eV -1 and -1.2×10 11 cm -2, respectively. These high values of Dit and negative Qf/ q could possibly be due to Ge out diffusion and pile up at the SiO 2/strained-Si interface. The oxide exhibits an excellent breakdown field of 15 MV cm -1.

  6. Nitrous Oxide Emissions from Ephemeral Wetland Soils are Correlated with Microbial Community Composition.

    PubMed

    Ma, Wai K; Farrell, Richard E; Siciliano, Steven D

    2011-01-01

    Nitrous oxide (N(2)O) is a greenhouse gas with a global warming potential far exceeding that of CO(2). Soil N(2)O emissions are a product of two microbially mediated processes: nitrification and denitrification. Understanding the effects of landscape on microbial communities, and the subsequent influences of microbial abundance and composition on the processes of nitrification and denitrification are key to predicting future N(2)O emissions. The objective of this study was to examine microbial abundance and community composition in relation to N(2)O associated with nitrification and denitrification processes over the course of a growing season in soils from cultivated and uncultivated wetlands. The denitrifying enzyme assay and [Formula: see text] pool dilution methods were used to compare the rates of denitrification and nitrification and their associated N(2)O emissions. Functional gene composition was measured with restriction fragment length polymorphism profiles and abundance was measured with quantitative polymerase chain reaction. The change in denitrifier nitrous oxide reductase gene (nosZ) abundance and community composition was a good predictor of net soil N(2)O emission. However, neither ammonia oxidizing bacteria ammonia monooxygenase (bacterial amoA) gene abundance nor composition predicted nitrification-associated-N(2)O emissions. Alternative strategies might be necessary if bacterial amoA are to be used as predictive in situ indicators of nitrification rate and nitrification-associated-N(2)O emission.

  7. Nitrous Oxide Emissions from Ephemeral Wetland Soils are Correlated with Microbial Community Composition

    PubMed Central

    Ma, Wai K.; Farrell, Richard E.; Siciliano, Steven D.

    2011-01-01

    Nitrous oxide (N2O) is a greenhouse gas with a global warming potential far exceeding that of CO2. Soil N2O emissions are a product of two microbially mediated processes: nitrification and denitrification. Understanding the effects of landscape on microbial communities, and the subsequent influences of microbial abundance and composition on the processes of nitrification and denitrification are key to predicting future N2O emissions. The objective of this study was to examine microbial abundance and community composition in relation to N2O associated with nitrification and denitrification processes over the course of a growing season in soils from cultivated and uncultivated wetlands. The denitrifying enzyme assay and N15O3− pool dilution methods were used to compare the rates of denitrification and nitrification and their associated N2O emissions. Functional gene composition was measured with restriction fragment length polymorphism profiles and abundance was measured with quantitative polymerase chain reaction. The change in denitrifier nitrous oxide reductase gene (nosZ) abundance and community composition was a good predictor of net soil N2O emission. However, neither ammonia oxidizing bacteria ammonia monooxygenase (bacterial amoA) gene abundance nor composition predicted nitrification-associated-N2O emissions. Alternative strategies might be necessary if bacterial amoA are to be used as predictive in situ indicators of nitrification rate and nitrification-associated-N2O emission. PMID:21712943

  8. Exchange of nitrous oxide within the Hudson Bay lowland

    NASA Technical Reports Server (NTRS)

    Schiller, C. L.; Hastie, D. R.

    1994-01-01

    The source strength of atmospheric trace gases from natural ecosystems must be quantified in order to assess the effect of such inputs on the background tropospheric chemistry. A static chamber technique and a gas exchange technique were used to determine the emissions of nitrous oxide from five sites within the Hudson Bay Lowland, as part of the Northern Wetland Study. Two mechanisms, one diffusive and the other episodic, were found likely to be responsible for the emissions of nitrous oxide. The annual diffusive flux ranged from -3.8 mg(N2O)/sq m in a treed bog to 7.9 mg(N2O)/sq m in an open fen. The addition of the episodic flux, increased this range to -2.1 mg(N2O)/sq m and 18.5 mg(N2O)/sq m respectively. These episodic emissions occurred in from 2.5% to 16.7% of the samples during the late summer peak emission period. Since the gas exchange rate could not detect the episodic emissions, it was found to be a poor method for water emission rate determination within the wetland. LANDSAT-Thermatic Mapper (TM) imagery was used to scale the emissions, from the chamber level to an integrated average over the entire Hudson Bay Lowland. The total emission rate of N2O from the Hudson Bay Lowland, was determined to be 1.2 Gg(N2O)/year, of which 80% was attributed to episodic emissions.

  9. Production, Isotopic Composition, and Atmospheric Fate of Biologically Produced Nitrous Oxide

    NASA Astrophysics Data System (ADS)

    Stein, Lisa Y.

    The anthropogenic production of greenhouse gases and their consequent effects on global climate have garnered international attention for years. A remaining challenge facing scientists is to unambiguously quantify both sources and sinks of targeted gases. Microbiological metabolism accounts for the largest source of nitrous oxide (N2O), mostly due to global conversion of land for agriculture and massive usage of nitrogen-based fertilizers. A most powerful method for characterizing the sources of N2O lies in its multi-isotope signature. This review summarizes mechanisms that lead to biological N2O production and how discriminate placement of 15N into molecules of N2O occurs. Through direct measurements and atmospheric modeling, we can now place a constraint on the isotopic composition of biological sources of N2O and trace its fate in the atmosphere. This powerful interdisciplinary combination of biology and atmospheric chemistry is rapidly advancing the closure of the global N2O budget.

  10. Nitrous Oxide for Labor Analgesia: Expanding Analgesic Options for Women in the United States

    PubMed Central

    Collins, Michelle R; Starr, Sarah A; Bishop, Judith T; Baysinger, Curtis L

    2012-01-01

    Nitrous oxide (N2O) is a commonly used labor analgesic in many Western countries, but is used infrequently in the United States. The University of California at San Francisco has been offering N2O for labor analgesia for more than 30 years. Vanderbilt University Medical Center recently began offering N2O as an option for pain relief in laboring women. Many women report that N2O provides effective pain relief during labor and argue that it should be made more widely available in the United States. This article discusses the use of N2O for pain management during labor, including its history, properties, clinical indications, and use and environmental safety issues. Practical issues regarding implementation of N2O service in a medical center setting are also discussed. PMID:23483795

  11. Mitigation of nitrous oxide emissions from soils by Bradyrhizobium japonicum inoculation

    NASA Astrophysics Data System (ADS)

    Itakura, Manabu; Uchida, Yoshitaka; Akiyama, Hiroko; Hoshino, Yuko Takada; Shimomura, Yumi; Morimoto, Sho; Tago, Kanako; Wang, Yong; Hayakawa, Chihiro; Uetake, Yusuke; Sánchez, Cristina; Eda, Shima; Hayatsu, Masahito; Minamisawa, Kiwamu

    2013-03-01

    Nitrous oxide (N2O) is a greenhouse gas that is also capable of destroying the ozone layer. Agricultural soil is the largest source of N2O (ref. ). Soybean is a globally important leguminous crop, and hosts symbiotic nitrogen-fixing soil bacteria (rhizobia) that can also produce N2O (ref. ). In agricultural soil, N2O is emitted from fertilizer and soil nitrogen. In soybean ecosystems, N2O is also emitted from the degradation of the root nodules. Organic nitrogen inside the nodules is mineralized to NH4+, followed by nitrification and denitrification that produce N2O. N2O is then emitted into the atmosphere or is further reduced to N2 by N2O reductase (N2OR), which is encoded by the nosZ gene. Pure culture and vermiculite pot experiments showed lower N2O emission by nosZ+ strains and nosZ++ strains (mutants with increased N2OR activity) of Bradyrhizobium japonicum than by nosZ- strains. A pot experiment using soil confirmed these results. Although enhancing N2OR activity has been suggested as a N2O mitigation option, this has never been tested in the field. Here, we show that post-harvest N2O emission from soybean ecosystems due to degradation of nodules can be mitigated by inoculation of nosZ+ and non-genetically modified organism nosZ++ strains of B. japonicum at a field scale.

  12. Nitrous oxide emissions from a commercial cornfield (Zea mays) measured using the eddy covariance technique

    NASA Astrophysics Data System (ADS)

    Huang, H.; Wang, J.; Hui, D.; Miller, D. R.; Bhattarai, S.; Dennis, S.; Smart, D.; Sammis, T.; Reddy, K. C.

    2014-12-01

    Increases in observed atmospheric concentrations of the long-lived greenhouse gas nitrous oxide (N2O) have been well documented. However, information on event-related instantaneous emissions during fertilizer applications is lacking. With the development of fast-response N2O analyzers, the eddy covariance (EC) technique can be used to gather instantaneous measurements of N2O concentrations to quantify the exchange of nitrogen between the soil and atmosphere. The objectives of this study were to evaluate the performance of a new EC system, to measure the N2O flux with the system, and finally to examine relationships of the N2O flux with soil temperature, soil moisture, precipitation, and fertilization events. An EC system was assembled with a sonic anemometer and a fast-response N2O analyzer (quantum cascade laser spectrometer) and applied in a cornfield in Nolensville, Tennessee during the 2012 corn growing season (4 April-8 August). Fertilizer amounts totaling 217 kg N ha-1 were applied to the experimental site. Results showed that this N2O EC system provided reliable N2O flux measurements. The cumulative emitted N2O amount for the entire growing season was 6.87 kg N2O-N ha-1. Seasonal fluxes were highly dependent on soil moisture rather than soil temperature. This study was one of the few experiments that continuously measured instantaneous, high-frequency N2O emissions in crop fields over a growing season of more than 100 days.

  13. Nitrous oxide emissions from tundra soil and snowpack in the maritime Antarctic.

    PubMed

    Zhu, Renbin; Sun, Liguang; Ding, Weixin

    2005-06-01

    The nitrous oxide emissions were measured at three tundra sites and one snowpack on the Fildes Peninsula in the maritime Antarctic in the summertime of 2002. The average fluxes at two normal tundra sites were 1.1+/-2.2 and 0.6+/-1.7 microg N2O m(-2)h(-1), respectively. The average flux from tundra soil site with penguin dropping addition was 3.7+/-2.0 microg N2O m(-2)h(-1), 3-6 times those from the normal tundra soils, suggesting that the deposition of fresh droppings enhanced N2O emissions during penguin breeding period. The summer precipitation had an important effect on N2O emissions; the flux decreased when heavy precipitation occurred. The diurnal cycle of the N2O fluxes from Antarctic tundra soils was not obtained due to local fluky weather conditions. The N2O fluxes through four snowpack sites were obtained by the vertical N2O concentration gradient and their average fluxes were 0.94, 1.36, 0.81 and 0.85 microg N2O m(-2)h(-1), respectively. The tundra soils under snowpack emitted N2O in the maritime Antarctic and increased local atmospheric N2O concentrations; therefore these fluxes could constitute an important part of the annual N2O budget for Antarctic tundra ecosystem.

  14. Indirect emissions of nitrous oxide from regional aquifers in the United Kingdom.

    PubMed

    Hiscock, K M; Bateman, A S; Mühlherr, I H; Fukada, T; Dennis, P F

    2003-08-15

    Diffuse pollution of groundwater by agriculture has caused elevated concentrations of nitrate (NO3-) and nitrous oxide (N2O) in regional aquifers. N2O is an important "greenhouse" gas, yet there are few estimates of indirect emissions of N2O from regional aquifers. In this study, high concentrations of N2O (mean 602 nM) were measured in the unconfined Chalk aquifer of eastern England, in an area of intensive agriculture. In contrast, pristine groundwaters from upland regions of England and Scotland, with predominantly natural vegetation cover, were found to have much lower concentrations of N2O (mean 27 nM). A positive relationship between N2O and NO3- concentrations and delta18O-NO3 values of between 3.36 and 16.00/1000 suggest that nitrification is the principal source of N2O. A calculated emission factor (EF5-g) of 0.0019 for indirect losses of N2O from Chalk groundwater is an order of magnitude lower than the value of 0.015 currently used in the Intergovernmental Panel on Climate Change (IPCC) methodology for assessing agricultural emissions. A flux of N2O from the major UK aquifers of 0.04 kg N2O-N ha(-1) a(-1) has been calculated using two approaches and suggests that indirect losses of N2O from regional aquifers are much less significant (<1%) than direct emissions from agricultural soils.

  15. Methane and nitrous oxide exchange over a managed hay meadow

    NASA Astrophysics Data System (ADS)

    Hörtnagl, L.; Wohlfahrt, G.

    2014-12-01

    The methane (CH4) and nitrous oxide (N2O) exchange of a temperate mountain grassland near Neustift, Austria, was measured during 2010-2012 over a time period of 22 months using the eddy covariance method. Exchange rates of both compounds at the site were low, with 97% of all half-hourly CH4 and N2O fluxes ranging between ±200 and ±50 ng m-2 s-1, respectively. The meadow acted as a sink for both compounds during certain time periods, but was a clear source of CH4 and N2O on an annual timescale. Therefore, both gases contributed to an increase of the global warming potential (GWP), effectively reducing the sink strength in terms of CO2 equivalents of the investigated grassland site. In 2011, our best guess estimate showed a net greenhouse gas (GHG) sink of -32 g CO2 equ. m-2 yr-1 for the meadow, whereby 55% of the CO2 sink strength of -71 g CO2 m-2 yr-1 was offset by CH4 (N2O) emissions of 7 (32) g CO2 equ. m-2 yr-1. When all data were pooled, the ancillary parameters explained 27 (42)% of observed CH4 (N2O) flux variability, and up to 62 (76)% on shorter timescales in-between management dates. In the case of N2O fluxes, we found the highest emissions at intermediate soil water contents and at soil temperatures close to 0 or above 14 °C. In comparison to CO2, H2O and energy fluxes, the interpretation of CH4 and N2O exchange was challenging due to footprint heterogeneity regarding their sources and sinks, uncertainties regarding post-processing and quality control. Our results emphasize that CH4 and N2O fluxes over supposedly well-aerated and moderately fertilized soils cannot be neglected when evaluating the GHG impact of temperate managed grasslands.

  16. Methane and nitrous oxide exchange over a managed hay meadow.

    PubMed

    Hörtnagl, L; Wohlfahrt, G

    2014-12-17

    The methane (CH4) and nitrous oxide (N2O) exchange of a temperate mountain grassland near Neustift, Austria, was measured during 2010-2012 over a time period of 22 months using the eddy covariance method. Exchange rates of both compounds at the site were low, with 97% of all half-hourly CH4 and N2O fluxes ranging between ±200 and ±50 ng m(-2) s(-1), respectively. The meadow acted as a sink for both compounds during certain time periods, but was a clear source of CH4 and N2O on an annual timescale. Therefore, both gases contributed to an increase of the global warming potential (GWP), effectively reducing the sink strength in terms of CO2 equivalents of the investigated grassland site. In 2011, our best guess estimate showed a net greenhouse gas (GHG) sink of -32 g CO2 equ. m(-2) yr(-1) for the meadow, whereby 55% of the CO2 sink strength of -71 g CO2m(-2) yr(-1) was offset by CH4 (N2O) emissions of 7 (32) g CO2 equ. m(-2) yr(-1). When all data were pooled, the ancillary parameters explained 27 (42)% of observed CH4 (N2O) flux variability, and up to 62 (76)% on shorter timescales in-between management dates. In the case of N2O fluxes, we found the highest emissions at intermediate soil water contents and at soil temperatures close to 0 or above 14 °C. In comparison to CO2, H2O and energy fluxes, the interpretation of CH4 and N2O exchange was challenging due to footprint heterogeneity regarding their sources and sinks, uncertainties regarding post-processing and quality control. Our results emphasize that CH4 and N2O fluxes over supposedly well-aerated and moderately fertilized soils cannot be neglected when evaluating the GHG impact of temperate managed grasslands.

  17. Measurement of nitrous oxide reductase activity in aquatic sediments

    USGS Publications Warehouse

    Miller, L.G.; Oremland, R.S.; Paulsen, S.

    1986-01-01

    Denitrification in aquatic sediments was measured by an N2O reductase assay. Sediments consumed small added quantities of N2O over short periods (a few hours). In experiments with sediment slurries, N2O reductase activity was inhibited by O2, C2H2, heat treatment, and by high levels of nitrate (1 mM) or sulfide (10 mM). However, ambient levels of nitrate (<100 μM) did not influence activity, and moderate levels (about 150 μM) induced only a short lag before reductase activity began. Moderate levels of sulfide (<1 mM) had no effect on N2O reductase activity. Nitrous oxide reductase displayed Michaelis-Menten kinetics in sediments from freshwater (Km = 2.17 μM), estuarine (Km = 14.5 μM), and alkaline-saline (Km = 501 μM) environments. An in situ assay was devised in which a solution of N2O was injected into sealed glass cores containing intact sediment. Two estimates of net rates of denitrification in San Francisco Bay under approximated in situ conditions were 0.009 and 0.041 mmol of N2O per m2 per h. Addition of chlorate to inhibit denitrification in these intact-core experiments (to estimate gross rates of N2O consumption) resulted in approximately a 14% upward revision of estimates of net rates. These results were comparable to an in situ estimate of 0.022 mmol of N2O per m2 per h made with the acetylene block assay.

  18. Nitrous Oxides Ozone Destructiveness Under Different Climate Scenarios

    NASA Technical Reports Server (NTRS)

    Kanter, David R.; McDermid, Sonali P.

    2016-01-01

    Nitrous oxide (N2O) is an important greenhouse gas and ozone depleting substance as well as a key component of the nitrogen cascade. While emissions scenarios indicating the range of N2O's potential future contributions to radiative forcing are widely available, the impact of these emissions scenarios on future stratospheric ozone depletion is less clear. This is because N2O's ozone destructiveness is partially dependent on tropospheric warming, which affects ozone depletion rates in the stratosphere. Consequently, in order to understand the possible range of stratospheric ozone depletion that N2O could cause over the 21st century, it is important to decouple the greenhouse gas emissions scenarios and compare different emissions trajectories for individual substances (e.g. business-as-usual carbon dioxide (CO2) emissions versus low emissions of N2O). This study is the first to follow such an approach, running a series of experiments using the NASA Goddard Institute for Space Sciences ModelE2 atmospheric sub-model. We anticipate our results to show that stratospheric ozone depletion will be highest in a scenario where CO2 emissions reductions are prioritized over N2O reductions, as this would constrain ozone recovery while doing little to limit stratospheric NOx levels (the breakdown product of N2O that destroys stratospheric ozone). This could not only delay the recovery of the stratospheric ozone layer, but might also prevent a return to pre-1980 global average ozone concentrations, a key goal of the international ozone regime. Accordingly, we think this will highlight the importance of reducing emissions of all major greenhouse gas emissions, including N2O, and not just a singular policy focus on CO2.

  19. Physical Processes and Nitrous Oxide Emissions Pre and Post-Freezing

    NASA Astrophysics Data System (ADS)

    Phillips, R. L.; Giltrap, D.; Kirschbaum, M.; Mcmillan, A. M.; Savage, K. E.; Davidson, E. A.

    2014-12-01

    Soil nitrous oxide (N2O) fluxes may be moderated by physical and biological processes, particularly when soils freeze and then thaw. There is a need to understand how physical processes affect above- canopy fluxes of N2O. There is also a need to understand the magnitude and duration of N2O emission peaks for agricultural fields, particularly the nitrogen-fixing legumes, which can produce and consume N2O in the plant root symbiosome. There are multiple potential sources of N2O, including bacteria and fungi in soil and in root symbiosomes. Further, N2O can be released when trapped in ice or dissolved in solution. These physical and biological processes can contribute to N2O fluxes measured above the canopy. In 2012-2013, we evaluated canopy, surface and belowground N2O data for a field seeded to lucerne (Medicago sativa). We used high-frequency data to determine above-canopy N2O fluxes using an Aerodyne Quantum Cascade Laser integrated with an eddy covariance system, and compared these with low-frequency flux and concentration data collected at the surface and belowground. Belowground moisture, temperature and soil data were used to partition measured N2O and CH4 into gaseous and dissolved phases. Pre and post-freeze data indicated the proportion of post-freeze flux previously trapped in ice. Nitrous oxide fluxes following a thaw event were compared with the amount of N2O trapped during freezing to determine the proportion of the flux resulting from previously trapped gases versus de novo N2O production.

  20. Modeling nitrous oxide emission from rivers: a global assessment.

    PubMed

    Hu, Minpeng; Chen, Dingjiang; Dahlgren, Randy A

    2016-11-01

    Estimates of global riverine nitrous oxide (N2 O) emissions contain great uncertainty. We conducted a meta-analysis incorporating 169 observations from published literature to estimate global riverine N2 O emission rates and emission factors. Riverine N2 O flux was significantly correlated with NH4 , NO3 and DIN (NH4  + NO3 ) concentrations, loads and yields. The emission factors EF(a) (i.e., the ratio of N2 O emission rate and DIN load) and EF(b) (i.e., the ratio of N2 O and DIN concentrations) values were comparable and showed negative correlations with nitrogen concentration, load and yield and water discharge, but positive correlations with the dissolved organic carbon : DIN ratio. After individually evaluating 82 potential regression models based on EF(a) or EF(b) for global, temperate zone and subtropical zone datasets, a power function of DIN yield multiplied by watershed area was determined to provide the best fit between modeled and observed riverine N2 O emission rates (EF(a): R(2)  = 0.92 for both global and climatic zone models, n = 70; EF(b): R(2)  = 0.91 for global model and R(2)  = 0.90 for climatic zone models, n = 70). Using recent estimates of DIN loads for 6400 rivers, models estimated global riverine N2 O emission rates of 29.6-35.3 (mean = 32.2) Gg N2 O-N yr(-1) and emission factors of 0.16-0.19% (mean = 0.17%). Global riverine N2 O emission rates are forecasted to increase by 35%, 25%, 18% and 3% in 2050 compared to the 2000s under the Millennium Ecosystem Assessment's Global Orchestration, Order from Strength, Technogarden, and Adapting Mosaic scenarios, respectively. Previous studies may overestimate global riverine N2 O emission rates (300-2100 Gg N2 O-N yr(-1) ) because they ignore declining emission factor values with increasing nitrogen levels and channel size, as well as neglect differences in emission factors corresponding to different nitrogen forms. Riverine N2 O emission estimates will be further enhanced through

  1. Patterns and controls of nitrous oxide emissions from waters draining a subtropical agricultural valley

    NASA Astrophysics Data System (ADS)

    Harrison, John; Matson, Pamela

    2003-09-01

    Although nitrous oxide (N2O) emission from agricultural runoff is thought to constitute a globally important source of this greenhouse gas, N2O flux from polluted aquatic systems is poorly understood and scarcely reported, especially in low-latitude (0°-30°) regions where rapid agricultural intensification is occurring. We measured N2O emissions, dissolved N2O concentrations, and factors likely to control rates of N2O production in drainage canals receiving agricultural and mixed agricultural/urban inputs from the intensively farmed Yaqui Valley of Sonora, Mexico. Average per-area N2O flux in both purely agricultural and mixed urban/agricultural drainage systems (16.5 ng N2O-N cm-2 hr-1) was high compared to other fresh water fluxes, and extreme values ranged up to 244.6 ng N2O-N cm-2 hr-1. These extremely high N2O fluxes occurred during green algae blooms, when organic carbon, nitrogen, and oxygen concentrations were high, and only in canals receiving pig-farm and urban inputs, suggesting an important link between land-use and N2O emissions. N2O concentrations and fluxes correlated significantly with water column concentrations of nitrate, particulate organic carbon and nitrogen, ammonium, and chlorophyll a, and a multiple linear regression model including ammonium, dissolved organic carbon, and particulate organic carbon was the best predictor of [N2O] (r2 = 52%). Despite high per-area N2O fluxes, our estimate of regional N2O emission from surface drainage (20,869 kg N2O-N yr-1; 0.046% of N-fertilizer inputs) was low compared to values predicted by algorithms used in global budgets.

  2. Monitoring atmospheric nitrous oxide background concentrations at Zhongshan Station, east Antarctica.

    PubMed

    Ye, Wenjuan; Bian, Lingen; Wang, Can; Zhu, Renbin; Zheng, Xiangdong; Ding, Minghu

    2016-09-01

    At present, continuous observation data for atmospheric nitrous oxide (N2O) concentrations are still lacking, especially in east Antarctica. In this paper, nitrous oxide background concentrations were measured at Zhongshan Station (69°22'25″S, 76°22'14″E), east Antarctica during the period of 2008-2012, and their interannual and seasonal characteristics were analyzed and discussed. The mean N2O concentration was 321.9nL/L with the range of 320.5-324.8nL/L during the five years, and it has been increasing at a rate of 0.29% year(-1). Atmospheric N2O concentrations showed a strong seasonal fluctuation during these five years. The concentrations appeared to follow a downtrend from spring to autumn, and then increased in winter. Generally the highest concentrations occurred in spring. This trend was very similar to that observed at other global observation sites. The overall N2O concentration at the selected global sites showed an increasing annual trend, and the mean N2O concentration in the Northern Hemisphere was slightly higher than that in the Southern Hemisphere. Our result could be representative of atmospheric N2O background levels at the global scale. This study provided valuable data for atmospheric N2O concentrations in east Antarctica, which is important to study on the relationships between N2O emissions and climate change.

  3. Assessment of nitrous oxide and methane emissions for California agriculture

    NASA Astrophysics Data System (ADS)

    Horwath, W. R.; Burger, M.; Assa, Y.; Wilson, T. J.

    2012-12-01

    The California Global Warming Solutions Act of 2006 (AB 32) mandates comprehensive strategies to reduce nitrous oxide (N2O) and methane (CH4) emissions. In agriculture crop production, sources of N2O are related to nitrogen fertilization while CH4 emission is associated with rice production. More than half the GHG emissions from agriculture are attributed to N2O production. Currently, baseline N2O emission data for most cropping systems in the State is lacking. Estimates of CH4 emission in rice have been established from previous studies, but a lack of information exists for its expansion into the San Joaquin Delta to address subsidence issues. The paucity of N2O emission data has hampered biogeochemical modeling efforts. The objectives of this assessment are to (1) measure annual N2O and CH4 emissions for major California crops (vineyards, almonds, tomato, wheat, alfalfa, lettuce, and rice) under typical management practices, (2) characterize the effects of environmental factors on the temporal profile of N2O and CH4 emissions, and (3) determine N2O emission factors. The growth of rice in Delta peat soils produced highly variable CH4 emissions depending on tillage intensity. In 2010, standard tillage produced 184 kg CH4-C/ha while in 2011 after deep plowing placing rice residue deeper into the soil, only 26 kg CH4-C/ha was observed. In processing tomato systems, an average 2.5 kg N2O-N/ha was emitted with standard fertilization (160 kg N / ha), similar to background emissions and those from a drip irrigated system, while 4.0 to 5.8 kg N2O-N /ha y-1 was emitted at fertilizer rates of 225 and 300 kg N /ha (see Fig. 1 for example of temporal sources of emissions). About half the annual emissions were emitted within 3 d after the first seasonal rainfall event. In other tomato studies, estimated losses of fertilizer N as N2O were 0.38 ± 0.03 kg/ha y-1 in a drip irrigated system and 1.79 ± 0.21 kg/ha y-1 in furrow irrigated system, which was equivalent to 0.19% and 0

  4. 29 CFR 1910.105 - Nitrous oxide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 5 2011-07-01 2011-07-01 false Nitrous oxide. 1910.105 Section 1910.105 Labor Regulations... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Hazardous Materials § 1910.105 Nitrous oxide. The piped systems for the in-plant transfer and distribution of nitrous oxide shall be designed, installed, maintained,...

  5. 29 CFR 1910.105 - Nitrous oxide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 5 2012-07-01 2012-07-01 false Nitrous oxide. 1910.105 Section 1910.105 Labor Regulations... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Hazardous Materials § 1910.105 Nitrous oxide. The piped systems for the in-plant transfer and distribution of nitrous oxide shall be designed, installed, maintained,...

  6. 29 CFR 1910.105 - Nitrous oxide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 5 2010-07-01 2010-07-01 false Nitrous oxide. 1910.105 Section 1910.105 Labor Regulations... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Hazardous Materials § 1910.105 Nitrous oxide. The piped systems for the in-plant transfer and distribution of nitrous oxide shall be designed, installed, maintained,...

  7. 29 CFR 1910.105 - Nitrous oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 5 2014-07-01 2014-07-01 false Nitrous oxide. 1910.105 Section 1910.105 Labor Regulations... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Hazardous Materials § 1910.105 Nitrous oxide. The piped systems for the in-plant transfer and distribution of nitrous oxide shall be designed, installed, maintained,...

  8. 29 CFR 1910.105 - Nitrous oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 5 2013-07-01 2013-07-01 false Nitrous oxide. 1910.105 Section 1910.105 Labor Regulations... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Hazardous Materials § 1910.105 Nitrous oxide. The piped systems for the in-plant transfer and distribution of nitrous oxide shall be designed, installed, maintained,...

  9. Nitrous oxide sedation and sexual phenomena.

    PubMed

    Jastak, J T; Malamed, S F

    1980-07-01

    Nine cases of sexual phenomena that occurred with use of nitrous oxide and oxygen sedation are described. Dentists involved routinely used concentrations of nitrous oxide greater than 50% and did not have assistants in the room during dental procedures. Recommendations on the concentrations of nitrous oxide and the presence of an assistant are made.

  10. Cage Compounds as Potential Energetic Oxidizers: A Theoretical Study of a Cage Isomer of N2O3

    DTIC Science & Technology

    2014-07-01

    Oxidizers: A Theoretical Study of a Cage Isomer of N2O3 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Robert J...of a Cage Isomer of N2O3 Robert J. Buszek[a] and Jerry A. Boatz*[b] Abstract: Ab initio electronic structure calculations are employed to investigate...Q. Z. Qin, Photoisomerization of N2O3 in an Ar matrix, J. Photochem. Photobio. A 1999, 122, 1-5. [15] a) A. Stirling , I. Papai, J. Mink, D. R

  11. Fact and Fiction of Nitrous Oxide Production By Nitrification

    NASA Astrophysics Data System (ADS)

    Stein, L. Y.; Kozlowski, J.; Stieglmeier, M.; Klotz, M. G.; Schleper, C.

    2014-12-01

    An accepted dogma in nitrification research is that ammonia-oxidizing bacteria (AOB) produce a modicum of nitrous oxide (N2O) during nitritation via incomplete oxidation of hydroxylamine, and substantially more at low oxygen concentrations via nitrifier denitrification.The nitrifier denitrification pathway involves the reduction of nitrite to N2O via nitric oxide and was thought to require activities of a copper-containing nitrite reductase (NirK) and nitric oxide reductase (NorB); inventory encoded in most, but not all AOB genome sequences. The discovery of nirK genes in ammonia-oxidizing Thaumarchaeota (AOA) resulted in a slew of publications stating that AOA must also perform nitrifier denitrification and, due to their high abundance, must control the majority of nitrification-linked N2O emissions. Prior to a publication by Stieglmeier et al. (2014), which definitively showed a lack of nitrifier denitrification by two axenic AOA cultures, other researchers relied on enrichment cultures, negative data, and heavy inferencing without direct demonstration of either a functional pathway or involvement of specific genes or enzymes. AOA genomes lack recognizable nitric oxide reductases and thermophilic AOA also lack nirK genes. Physiological and microrespirometry experiments with axenic AOB and AOA cultures allowed us to demonstrate that: 1) AOB produce N2O via nitrifier denitrification even though some lack annotated nirK and/or norB genes; 2) nitrifier denitrification by AOB is reliant on nitric oxide but ammonia oxidation is not; 3) ammonia oxidation by AOA is reliant on production of nitric oxide; 4) AOA are incapable of generating N2O via nitrifier denitrification; 5) N2O production by AOA is from chemical interactions between NO and media components, most likely not by enzyme activity. Our results reveal operation of different N oxide transformation pathways in AOB and AOA governed by different environmental controls and involving different mechanisms of N2O

  12. Direct Nitrous Oxide Emission from the Aquacultured Pacific White Shrimp (Litopenaeus vannamei)

    PubMed Central

    Heisterkamp, Ines M.; Schramm, Andreas; de Beer, Dirk

    2016-01-01

    ABSTRACT The Pacific white shrimp (Litopenaeus vannamei) is widely used in aquaculture, where it is reared at high stocking densities, temperatures, and nutrient concentrations. Here we report that adult L. vannamei shrimp emit the greenhouse gas nitrous oxide (N2O) at an average rate of 4.3 nmol N2O/individual × h, which is 1 to 2 orders of magnitude higher than previously measured N2O emission rates for free-living aquatic invertebrates. Dissection, incubation, and inhibitor experiments with specimens from a shrimp farm in Germany indicated that N2O is mainly produced in the animal's gut by microbial denitrification. Microsensor measurements demonstrated that the gut interior is anoxic and nearly neutral and thus is favorable for denitrification by ingested bacteria. Dinitrogen (N2) and N2O accounted for 64% and 36%, respectively, of the nitrogen gas flux from the gut, suggesting that the gut passage is too fast for complete denitrification to be fully established. Indeed, shifting the rearing water bacterial community, a diet component of shrimp, from oxic to anoxic conditions induced N2O accumulation that outlasted the gut passage time. Shrimp-associated N2O production was estimated to account for 6.5% of total N2O production in the shrimp farm studied here and to contribute to the very high N2O supersaturation measured in the rearing tanks (2,099%). Microbial N2O production directly associated with aquacultured animals should be implemented into life cycle assessments of seafood production. IMPORTANCE The most widely used shrimp species in global aquaculture, Litopenaeus vannamei, is shown to emit the potent greenhouse gas nitrous oxide (N2O) at a particularly high rate. Detailed experiments reveal that N2O is produced in the oxygen-depleted gut of the animal by bacteria that are part of the shrimp diet. Upon ingestion, these bacteria experience a shift from oxic to anoxic conditions and therefore switch their metabolism to the anaerobic denitrification

  13. N2O emissions from a nitrogen-enriched river

    USGS Publications Warehouse

    McMahon, P.B.; Dennehy, K.F.

    1999-01-01

    Nitrous oxide (N2O) emissions from the South Platte River in Colorado were measured using closed chambers in the fall, winter, and summer of 1994- 1995. The South Platte River was enriched in inorganic N (9-800 ??M) derived from municipal wastewater effluent and groundwater return flows from irrigated agricultural fields. River water was as much as 2500% supersaturated with N2O, and median N2O emission rates from the river surface ranged from less than 90 to 32 600 ??g-N m-2 d-1. Seventy-nine percent of the variance in N2O emission rates was explained by concentrations of total inorganic N in river water and by water temperature. The estimated total annual N2O emissions from the South Platte River were 2 x 1013-6 x 1013 ??g-N yr-1. This amount of annual N2O emissions was similar to the estimated annual N2O emissions from all primary municipal wastewater treatment processes in the United States (1). Results from this study indicate that N-enriched rivers could be important anthropogenic sources of N2O to the atmosphere. However, N2O emission measurements from other N-enriched rivers are needed to better quantify this source.Nitrous oxide (N2O) emissions from the South Platte River in Colorado were measured using closed chambers in the fall, winter, and summer of 1994-1995. The South Platte River was enriched in inorganic N (9-800 ??M) derived from municipal wastewater effluent and groundwater return flows from irrigated agricultural fields. River water was as much as 2500% supersaturated with N2O, and median N2O emission rates from the river surface ranged from less than 90 to 32 600 ??g-N m-2 d-1. Seventy-nine percent of the variance in N2O emission rates was explained by concentrations of total inorganic N in river water and by water temperature. The estimated total annual N2O emissions from the South Platte River were 2??1013-6??1013 ??g-N yr-1. This amount of annual N2O emissions was similar to the estimated annual N2O emissions from all primary municipal

  14. Enhanced biogenic emissions of nitric oxide and nitrous oxide following surface biomass burning

    NASA Technical Reports Server (NTRS)

    Anderson, Iris C.; Levine, Joel S.; Poth, Mark A.; Riggan, Philip J.

    1988-01-01

    Recent measurements indicate significantly enhanced biogenic soil emissions of both nitric oxide (NO) and nitrous oxide (N2O) following surface burning. These enhanced fluxes persisted for at least six months following the burn. Simultaneous measurements indicate enhanced levels of exchangeable ammonium in the soil following the burn. Biomass burning is known to be an instantaneous source of NO and N2O resulting from high-temperature combustion. Now it is found that biomass burning also results in significantly enhanced biogenic emissions of these gases, which persist for months following the burn.

  15. Denitrifying kinetics and nitrous oxide emission under different copper concentrations.

    PubMed

    Wu, Guangxue; Zhai, Xiaofeng; Jiang, Chengai; Guan, Yuntao

    2014-01-01

    Denitrifying activities and nitrous oxide (N2O) emission during denitrification can be affected by copper concentrations. Different denitrifiers were acclimated in sequencing batch reactors with acetate or methanol as the electron donor and nitrate as the electron acceptor. The effect of copper concentrations on the denitrifying activity and N2O emission for the acclimated denitrifiers was examined in batch experiments. Denitrifying activities of the acclimated denitrifiers declined with increasing copper concentrations, and the copper concentration exhibited a higher effect on denitrifiers acclimated with acetate than those acclimated with methanol. Compared with the control without the addition of copper, at the copper concentration of 1 mg/L, the acetate utilization rate reduced by 89% for acetate-acclimated denitrifiers, while the methanol utilization rate only reduced by 15% for methanol-acclimated denitrifiers. Copper also had different effects on N2O emission during denitrification carried out by various types of denitrifiers. For the acetate-acclimated denitrifiers, N2O emission initially increased and then decreased with increasing copper concentrations, while for the methanol-acclimated denitrifiers, N2O emission decreased with increasing copper concentrations.

  16. Recent advances in mathematical modeling of nitrous oxides emissions from wastewater treatment processes.

    PubMed

    Ni, Bing-Jie; Yuan, Zhiguo

    2015-12-15

    Nitrous oxide (N2O) can be emitted from wastewater treatment contributing to its greenhouse gas footprint significantly. Mathematical modeling of N2O emissions is of great importance toward the understanding and reduction of the environmental impact of wastewater treatment systems. This article reviews the current status of the modeling of N2O emissions from wastewater treatment. The existing mathematical models describing all the known microbial pathways for N2O production are reviewed and discussed. These included N2O production by ammonia-oxidizing bacteria (AOB) through the hydroxylamine oxidation pathway and the AOB denitrification pathway, N2O production by heterotrophic denitrifiers through the denitrification pathway, and the integration of these pathways in single N2O models. The calibration and validation of these models using lab-scale and full-scale experimental data is also reviewed. We conclude that the mathematical modeling of N2O production, while is still being enhanced supported by new knowledge development, has reached a maturity that facilitates the estimation of site-specific N2O emissions and the development of mitigation strategies for a wastewater treatment plant taking into the specific design and operational conditions of the plant.

  17. The effect of soil moisture on nitrous oxide production rates in large enclosed ecosystems

    NASA Astrophysics Data System (ADS)

    van Haren, J.; Colodner, D.; Lin, G.; Murthy, R.

    2001-12-01

    On land, nitrous oxide (N2O) is mainly produced in soils by bacterial processes such as nitrification and denitrification. Once in the atmosphere N2O contributes to the greenhouse effect and stratospheric ozone destruction. Nitrification and denitrification are strongly dependent on soil moisture content, amongst other soil parameters. At Biosphere 2 Center we have begun to test the utility of meso-scale closed systems for understanding the relationship between soil properties and trace gas production at larger scales. We investigated the relationship between soil moisture content and soil N2O efflux in two large experimental closed systems (Tropical Rainforest (TR) and Intensive Forestry (IF) Mesocosms) at Biosphere 2 Center. N2O was measured every hour with an automated GC system. The daily N2O production rate was calculated as the rate of increase of N2O during the daytime, when the mesocosm was materially closed. We furthermore measured N2O and nitrate concentrations in the soil, as well as nitrate and N2O production rates in local areas. In the Rainforest Mesocosm, we found a very reproducible relationship between soil moisture content and N2O efflux, including the transient spikes in production rate upon wetting. In the Forestry Mesocosm the relation between soil moisture and N2O efflux was less clearcut.

  18. Evaluating the Role of Microbial Internal Storage Turnover on Nitrous Oxide Accumulation During Denitrification

    PubMed Central

    Liu, Yiwen; Peng, Lai; Guo, Jianhua; Chen, Xueming; Yuan, Zhiguo; Ni, Bing-Jie

    2015-01-01

    Biological wastewater treatment processes under a dynamic regime with respect to carbon substrate can result in microbial storage of internal polymers (e.g., polyhydroxybutyrate (PHB)) and their subsequent utilizations. These storage turnovers play important roles in nitrous oxide (N2O) accumulation during heterotrophic denitrification in biological wastewater treatment. In this work, a mathematical model is developed to evaluate the key role of PHB storage turnovers on N2O accumulation during denitrification for the first time, aiming to establish the key relationship between N2O accumulation and PHB storage production. The model is successfully calibrated and validated using N2O data from two independent experimental systems with PHB storage turnovers. The model satisfactorily describes nitrogen reductions, PHB storage/utilization, and N2O accumulation from both systems. The results reveal a linear relationship between N2O accumulation and PHB production, suggesting a substantial effect of PHB storage on N2O accumulation during denitrification. Application of the model to simulate long-term operations of a denitrifying sequencing batch reactor and a denitrifying continuous system indicates the feeding pattern and sludge retention time would alter PHB turnovers and thus affect N2O accumulation. Increasing PHB utilization could substantially raise N2O accumulation due to the relatively low N2O reduction rate when using PHB as carbon source. PMID:26463891

  19. Evaluating the Role of Microbial Internal Storage Turnover on Nitrous Oxide Accumulation During Denitrification.

    PubMed

    Liu, Yiwen; Peng, Lai; Guo, Jianhua; Chen, Xueming; Yuan, Zhiguo; Ni, Bing-Jie

    2015-10-14

    Biological wastewater treatment processes under a dynamic regime with respect to carbon substrate can result in microbial storage of internal polymers (e.g., polyhydroxybutyrate (PHB)) and their subsequent utilizations. These storage turnovers play important roles in nitrous oxide (N2O) accumulation during heterotrophic denitrification in biological wastewater treatment. In this work, a mathematical model is developed to evaluate the key role of PHB storage turnovers on N2O accumulation during denitrification for the first time, aiming to establish the key relationship between N2O accumulation and PHB storage production. The model is successfully calibrated and validated using N2O data from two independent experimental systems with PHB storage turnovers. The model satisfactorily describes nitrogen reductions, PHB storage/utilization, and N2O accumulation from both systems. The results reveal a linear relationship between N2O accumulation and PHB production, suggesting a substantial effect of PHB storage on N2O accumulation during denitrification. Application of the model to simulate long-term operations of a denitrifying sequencing batch reactor and a denitrifying continuous system indicates the feeding pattern and sludge retention time would alter PHB turnovers and thus affect N2O accumulation. Increasing PHB utilization could substantially raise N2O accumulation due to the relatively low N2O reduction rate when using PHB as carbon source.

  20. Occurrence of nitrous oxide in the central High Plains aquifer, 1999

    USGS Publications Warehouse

    McMahon, P.B.; Bruch, B.W.; Becker, M.F.; Pope, L.M.; Dennehy, K.F.

    2000-01-01

    Nitrogen-enriched groundwater has been proposed as an important anthropogenic source of atmospheric nitrous oxide (N2O), yet few measurements of N2O in large aquifer systems have been made. Concentrations of N2O in water samples collected from the 124 000 km2 central High Plains aquifer in 1999 ranged from < 1 to 940 nM, with a median concentration of 29 nM (n = 123). Eighty percent of the N20 concentrations exceeded the aqueous concentration expected from equilibration with atmospheric N2O. Measurements of N2O, NO3-, and 3H in unsaturated-zone sediments, recently recharged groundwater, and older groundwater indicate that concentrations of N2O in groundwater increased over time and will likely continue to increase in the future as N-enriched water recharges the aquifer. Large concentrations of O2 and NO3- and small concentrations of NH4+ and dissolved organic carbon in the aquifer indicate that N2O in the central High Plains aquifer was produced primarily by nitrification. Calculations indicate that the flux of N2O from the central High Plains aquifer to the atmosphere from well pumping and groundwater discharge to streams was not a significant source of atmospheric N2O.Nitrogen-enriched groundwater has been proposed as an important anthropogenic source of atmospheric nitrous oxide (N2O), yet few measurements of N2O in large aquifer systems have been made. Concentrations of N2O in water samples collected from the 124000 km2 central High Plains aquifer in 1999 ranged from < 1 to 940 nM, with a median concentration of 29 nM (n = 123). Eighty percent of the N2O concentrations exceeded the aqueous concentration expected from equilibration with atmospheric N2O. Measurements of N2O, NO3-, and 3H in unsaturated-zone sediments, recently recharged groundwater, and older groundwater indicate that concentrations of N2O in groundwater increased over time and will likely continue to increase in the future as N-enriched water recharges the aquifer. Large concentrations of O2 and

  1. Nitrous oxide emission related to ammonia-oxidizing bacteria and mitigation options from N fertilization in a tropical soil

    NASA Astrophysics Data System (ADS)

    Soares, Johnny R.; Cassman, Noriko A.; Kielak, Anna M.; Pijl, Agata; Carmo, Janaína B.; Lourenço, Kesia S.; Laanbroek, Hendrikus J.; Cantarella, Heitor; Kuramae, Eiko E.

    2016-07-01

    Nitrous oxide (N2O) from nitrogen fertilizers applied to sugarcane has high environmental impact on ethanol production. This study aimed to determine the main microbial processes responsible for the N2O emissions from soil fertilized with different N sources, to identify options to mitigate N2O emissions, and to determine the impacts of the N sources on the soil microbiome. In a field experiment, nitrogen was applied as calcium nitrate, urea, urea with dicyandiamide or 3,4 dimethylpyrazone phosphate nitrification inhibitors (NIs), and urea coated with polymer and sulfur (PSCU). Urea caused the highest N2O emissions (1.7% of N applied) and PSCU did not reduce cumulative N2O emissions compared to urea. NIs reduced N2O emissions (95%) compared to urea and had emissions comparable to those of the control (no N). Similarly, calcium nitrate resulted in very low N2O emissions. Interestingly, N2O emissions were significantly correlated only with bacterial amoA, but not with denitrification gene (nirK, nirS, nosZ) abundances, suggesting that ammonia-oxidizing bacteria, via the nitrification pathway, were the main contributors to N2O emissions. Moreover, the treatments had little effect on microbial composition or diversity. We suggest nitrate-based fertilizers or the addition of NIs in NH4+-N based fertilizers as viable options for reducing N2O emissions in tropical soils and lessening the environmental impact of biofuel produced from sugarcane.

  2. Nitrous oxide emission related to ammonia-oxidizing bacteria and mitigation options from N fertilization in a tropical soil

    PubMed Central

    Soares, Johnny R.; Cassman, Noriko A.; Kielak, Anna M.; Pijl, Agata; Carmo, Janaína B.; Lourenço, Kesia S.; Laanbroek, Hendrikus J.; Cantarella, Heitor; Kuramae, Eiko E.

    2016-01-01

    Nitrous oxide (N2O) from nitrogen fertilizers applied to sugarcane has high environmental impact on ethanol production. This study aimed to determine the main microbial processes responsible for the N2O emissions from soil fertilized with different N sources, to identify options to mitigate N2O emissions, and to determine the impacts of the N sources on the soil microbiome. In a field experiment, nitrogen was applied as calcium nitrate, urea, urea with dicyandiamide or 3,4 dimethylpyrazone phosphate nitrification inhibitors (NIs), and urea coated with polymer and sulfur (PSCU). Urea caused the highest N2O emissions (1.7% of N applied) and PSCU did not reduce cumulative N2O emissions compared to urea. NIs reduced N2O emissions (95%) compared to urea and had emissions comparable to those of the control (no N). Similarly, calcium nitrate resulted in very low N2O emissions. Interestingly, N2O emissions were significantly correlated only with bacterial amoA, but not with denitrification gene (nirK, nirS, nosZ) abundances, suggesting that ammonia-oxidizing bacteria, via the nitrification pathway, were the main contributors to N2O emissions. Moreover, the treatments had little effect on microbial composition or diversity. We suggest nitrate-based fertilizers or the addition of NIs in NH4+-N based fertilizers as viable options for reducing N2O emissions in tropical soils and lessening the environmental impact of biofuel produced from sugarcane. PMID:27460335

  3. Treatment of N2O in pulsed microwave torch discharge

    NASA Astrophysics Data System (ADS)

    Jasiński, M.; Czylkowski, D.; Zakrzewski, Z.; Mizeraczyk, J.

    2004-03-01

    Results of using a moderate-power (several hundred Watts) pulsed microwave torch plasma (MTP) to the conversion of atmospheric-pressure nitrous oxide (N2O) into nitrogen oxides (NO, NO2 and N2O4) are presented. The pulsed regime allowed to decrease the average power used, resulting in a higher value of energy efficiency by about 10% (reaching several hundred g[N2O]/kWh) at the same efficiency of the decomposition of N2O (70÷90%) as at the continuous operation of MTP. The removal rate increased up to 200 g[N2O]/h. The obtained results suggest the pulsed MTP promising for efficient decomposition of various gaseous pollutants, e.g. fluorocarbons.

  4. Nitrous oxide production by Alcaligenes faecalis under transient and dynamic aerobic and anaerobic conditions

    SciTech Connect

    Otte, S.; Grobben, N.G.; Robertson, L.A.; Jetten, M.S.M.; Kuenen, J.G.

    1996-07-01

    Nitrous oxide production contributes to both greenhouse effect and ozone depletion in the stratosphere. A significant part of the global N2O emission can be attributed to microbial processes, especially nitrification and denitrification, used in biological wastewater treatment systems. This study looks at the efficiency of denitrification and the enzymes involved, with the emphasis on N2O production during the transient phase from aerobic to anaerobic conditions and vice versa. The effect of repetitive changing aerobic-anaerobic conditions on N2O was also studied. Alcaligenes faecalis was used as the model denitrofing organism. 35 refs., 3 figs., 1 tab.

  5. Soil invertebrate fauna affect N2 O emissions from soil.

    PubMed

    Kuiper, Imke; de Deyn, Gerlinde B; Thakur, Madhav P; van Groenigen, Jan Willem

    2013-09-01

    Nitrous oxide (N2 O) emissions from soils contribute significantly to global warming. Mitigation of N2 O emissions is severely hampered by a lack of understanding of its main controls. Fluxes can only partly be predicted from soil abiotic factors and microbial analyses - a possible role for soil fauna has until now largely been overlooked. We studied the effect of six groups of soil invertebrate fauna and tested the hypothesis that all of them increase N2 O emissions, although to different extents. We conducted three microcosm experiments with sandy soil and hay residue. Faunal groups included in our experiments were as follows: fungal-feeding nematodes, mites, springtails, potworms, earthworms and isopods. In experiment I, involving all six faunal groups, N2 O emissions declined with earthworms and potworms from 78.4 (control) to 37.0 (earthworms) or 53.5 (potworms) mg N2 O-N m(-2) . In experiment II, with a higher soil-to-hay ratio and mites, springtails and potworms as faunal treatments, N2 O emissions increased with potworms from 51.9 (control) to 123.5 mg N2 O-N m(-2) . Experiment III studied the effect of potworm density; we found that higher densities of potworms accelerated the peak of the N2 O emissions by 5 days (P < 0.001), but the cumulative N2 O emissions remained unaffected. We propose that increased soil aeration by the soil fauna reduced N2 O emissions in experiment I, whereas in experiment II N2 O emissions were driven by increased nitrogen and carbon availability. In experiment III, higher densities of potworms accelerated nitrogen and carbon availability and N2 O emissions, but did not increase them. Overall, our data show that soil fauna can suppress, increase, delay or accelerate N2 O emissions from soil and should therefore be an integral part of future N2 O studies.

  6. Nitrous oxide fluxes from three forest types of the tropical mountain rainforests on Hainan Island, China

    NASA Astrophysics Data System (ADS)

    Bai, Zhenzhi; Yang, Gang; Chen, Huai; Zhu, Qiuan; Chen, Dexiang; Li, Yide; Wang, Xu; Wu, Zhongmin; Zhou, Guangyi; Peng, Changhui

    2014-08-01

    Tropical rainforest soil is an important source of atmospheric nitrous oxide (N2O). However, there is still considerable uncertainty about the spatial and temporal variability of N2O fluxes. To understand these fluxes, we quantified the annual N2O emissions from three tropical mountain rainforests (primary mountain rainforest, PMR; secondary mountain rainforest, SMR; and Podocarpus imbricatus plantation, PIP) in the Jianfengling National Natural Reserve on Hainan Island, China. The average of N2O emissions in this area was 2.52 ± 0.33 kg N-N2O ha-1 yr-1 (3.52 kg N-N2O ha-1 yr-1 in the wet season and 1.62 kg N-N2O ha-1 yr-1 in the dry season) during our study period, with highly seasonal variations. The mean N2O emission rates were significantly higher during the wet season (68% of the total average) than the dry season (32% of the total average) (P < 0.05). PIP had the highest N2O emission rate at 3.49 ± 0.61 kg N-N2O ha-1 yr-1 (4.74 kg N-N2O ha-1 yr-1 in the wet season and 2.32 kg N-N2O ha-1 yr-1 in the dry season), followed by SMR at 3.03 ± 0.64 kg N-N2O ha-1 yr-1 (4.16 kg N-N2O ha-1 yr-1 in the wet season and 1.97 kg N-N2O ha-1 yr-1 in the dry season), and then PMR at 1.53 ± 0.49 kg N-N2O ha-1 yr-1 (2.21 kg N-N2O ha-1 yr-1 in the wet season and 0.94 kg N-N2O ha-1 yr-1 in the dry season). We observed a significant Gaussian relationship between the N2O fluxes and soil temperature for SMR and PIP but no significant relationship in PMR. There was a significant exponential relationship between the N2O fluxes and water filled pore space (WFPS) in SMR and PIP but not in PMR.

  7. Nitrous oxide cycling in the Black Sea inferred from stable isotope and isotopomer distributions

    NASA Astrophysics Data System (ADS)

    Westley, Marian B.; Yamagishi, Hiroaki; Popp, Brian N.; Yoshida, Naohiro

    2006-08-01

    The low-oxygen regions of the world's oceans have been shown to be major sources of nitrous oxide, a trace gas in the atmosphere that contributes to both greenhouse warming and the destruction of stratospheric ozone. Nitrous oxide can be produced as a by-product of nitrification or an intermediate of denitrification; low oxygen conditions enhance the yield of nitrous oxide from both pathways. We measured the concentration and isotopic composition of dissolved nitrous oxide at several stations in the Black Sea, an anoxic basin with a well-defined suboxic layer that separates the ventilated surface waters from the sulfidic deep waters. Our data show that in contrast to other low-oxygen marine regions, nitrous oxide does not accumulate in the Black Sea at significant levels. Moreover, whereas the reduction of nitrous oxide by denitrification usually yields residual gas that is enriched in both stable isotopes, in the Black Sea declining nitrous oxide concentrations are accompanied by enrichment in 18O-N 2O but depletion in 15N-N 2O. We measured a minimum δ15N-N 2O value of -10.8±0.8‰ vs. air N 2, by far the lowest measured to date for seawater. Measurements of the distribution of 15N within the linear nitrous oxide molecule reveal that this unusual isotopic signal is most pronounced in the end-position nitrogen, and that site preference, or the tendency for 15N to be found in the center-position nitrogen, co-varies positively with 18O-N 2O. We surmise that the highly unusual isotopic composition of Black Sea nitrous oxide is the result of two processes: production of 15N-depleted nitrous oxide by ammonium oxidation followed by its reduction by denitrification, which causes enrichment in 18O and enhancement of 15N-site preference. Bottle incubation experiments with 15N-ammonium and 15N-nitrite reveal that both oxidation and reduction pathways to nitrous oxide are active in the Black Sea suboxic zone.

  8. Effect of high frequency surface and subsurface drip irrigations on N2O emissions in orchards

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fertilized agricultural soil is a source for greenhouse gas nitrous oxide (N2O) emissions. A sustainable agricultural practice needs to consider minimizing N2O emissions while increasing N use efficiency and maintaining crop economic yield and quality. In order to develop a sustainable crop producti...

  9. Partitioning N2O emissions within the US Corn Belt using an inverse modeling approach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) emissions within the US Corn Belt have been estimated to be 2- to 9-11 fold larger than predictions from emission inventories, implying that one or more source 12 categories in bottom-up approaches are underestimated. Here we interpret hourly N2O 13 mixing ratios measured during ...

  10. Catalytic oxidation of H2 by N2O in the gas phase: O-atom transport with atomic metal cations.

    PubMed

    Blagojevic, Voislav; Bozović, Andrea; Orlova, Galina; Bohme, Diethard K

    2008-10-16

    Twenty-five atomic cations, M (+), that lie within the thermodynamic window for O-atom transport catalysis of the oxidation of hydrogen by nitrous oxide, have been checked for catalytic activity at room temperature with kinetic measurements using an inductively-coupled plasma/selected-ion flow tube (ICP/SIFT) tandem mass spectrometer. Only 4 of these 25 atomic cations were seen to be catalytic: Fe (+), Os (+), Ir (+), and Pt (+). Two of these, Ir (+) and Pt (+), are efficient catalysts, while Fe (+) and Os (+) are not. Eighteen atomic cations (Cr (+), Mn (+), Co (+), Ni (+), Cu (+), Ge (+), Se (+), Mo (+), Ru (+), Rh (+), Sn (+), Te (+), Re (+), Pb (+), Bi (+), Eu (+), Tm (+), and Yb (+)) react too slowly at room temperature either in their oxidation with N 2O to form MO (+) or in the reduction of MO (+) by H 2. Many of these reactions are known to be spin forbidden and a few actually may lie outside the thermodynamic window. Three alkaline-earth metal monoxide cations, CaO (+), SrO (+), and BaO (+), were observed to favor MOH (+) formation in their reactions with H 2. A potential-energy landscape is computed for the oxidation of H 2 with N 2O catalyzed by Fe (+)( (6)D) that vividly illustrates the operation of an ionic catalyst and qualitatively accounts for the relative inefficiency of this catalyst.

  11. Nitrous oxide production by nitrification and denitrification in the Eastern Tropical South Pacific oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Ji, Qixing; Babbin, Andrew R.; Jayakumar, Amal; Oleynik, Sergey; Ward, Bess B.

    2015-12-01

    The Eastern Tropical South Pacific oxygen minimum zone (ETSP-OMZ) is a site of intense nitrous oxide (N2O) flux to the atmosphere. This flux results from production of N2O 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 15N tracers. The highest N2O production rates occurred at the depth of peak N2O concentrations at the oxic-anoxic interface above the oxygen deficient zone (ODZ) because slightly oxygenated waters allowed (1) N2O 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 N2O 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 N2O production in the ETSP-OMZ.

  12. Stable isotopes in nitrous oxide emitted from tropical rain forest soils and agricultural fields: Implications for the global atmospheric nitrous oxide budget

    NASA Astrophysics Data System (ADS)

    Perez, Tibisay Josefina

    Nitrous oxide (N2O) is an important greenhouse gas and is the primary source of NOx in the stratosphere. Large uncertainties exist in the global N2O budget, mainly due to the high uncertainty associated with source estimates. Recently, stable isotopes of 15N and 18O have been proposed as a tool to better constrain the N2O global budget. This thesis develops analytical methods for constraining and measuring stable isotopes in N2O emitted from soils and reports initial investigations of N2O isotopes from the largest sources in the global N2O budget: tropical rain forest soils and agricultural fields. We found significant differences in the isotopic composition of N 2O emitted from tropical rain forest soils and fertilized agricultural fields. Differences were largest for 15N. Emission-weighted δ 15N-N2O were -26 +/- 2.5‰ s.d., n = 3 (Costa Rican forest), -6.6 +/- 11.3‰ s.d. n = 14 (Brazilian forest) and -36.7 +/- 9.2‰ s.d. n = 19 (Mexican agricultural field and Costa Rican Papaya plantation). We attribute the large range in δ 15N from tropical rain forests, where denitrification is the main source of N2O, to differences in the degree of N2O to N2 reduction. We attribute the very light δ15N values in fertilized agricultural fields to the enhanced nitrogen availability in the soils which facilitates higher fractionation between substrates and products. Similarly, in the Brazilian tropical forest lighter δ 15N-N2O from a local area of enhanced emission is attributed to locally more abundant N- substrate in that particular soil site. If the increase of N2O in the troposphere over the past 100 years is attributable to increased use of N fertilizer, and assuming that light δ 15N- N2O isotopic values are associated with agricultural practices, we expect the δ15N-N2O in the troposphere to have decreased since pre-industrial times. Theoretically, comparison of 15N and 18O signature of emitted N2O with precursors species (NO3 -, NH4+, H2O and O 2) should uniquely

  13. Aquatic sources and sinks for nitrous oxide

    NASA Technical Reports Server (NTRS)

    Elkins, J. W.; Wofsy, S. C.; Mcelroy, M. B.; Kaplan, W. A.; Kolb, C. E.

    1978-01-01

    Data are presented which suggest the complexity of the aquatic nitrogen cycle as it affects N2O. The data are from studies made in the central and south-east tropical regions of the Pacific Ocean and in Chesapeake Bay. The data indicate that oxidation of ammonium and amino nitrogen and nitrification form the principle source for marine N2O. It is estimated that the yearly global yield for oceanic N2O is less than about 10 to the 7th power tons. The consumption of atmospheric N2O by the open ocean has not been evidenced, although data from the south-east tropical Pacific and Chesapeake Bay show the consumption of dissolved N2O in low-oxygen conditions. Preliminary observations have also indicated the consumption of atmospheric N2O by aquatic systems such as freshwater pond and a tidal saltmarsh.

  14. Retrieval of the Nitrous Oxide Profiles using the AIRS Data in China

    NASA Astrophysics Data System (ADS)

    Chen, L.; Ma, P.; Tao, J.; Li, X.; Zhang, Y.; Wang, Z.; Li, S.; Xiong, X.

    2014-12-01

    As an important greenhouse gas and ozone-depleting substance, the 100-year global warming potential of Nitrous Oxide (N2O) is almost 300 times higher than that of carbon dioxide. However, there are still large uncertainties about the quantitative N2O emission and its feedback to climate change due to the coarse ground-based network. This approach attempts to retrieve the N2O profiles from the Atmospheric InfraRed Sounder (AIRS) data. First, the sensitivity of atmospheric temperature and humidity profiles and surface parameters between two spectral absorption bands were simulated by using the radiative transfer model. Second, the eigenvector regression algorithm is used to construct a priori state. Third, an optimal estimate method was developed based on the band selection of N2O. Finally, we compared our retrieved AIRS profiles with HIPPO data, and analyzed the seasonal and annual N2O distribution in China from 2004 to 2013.

  15. Comparison of extracellular dopamine concentration in awake unstressed and postsurgical nitrous oxide sedated rats.

    PubMed

    Kofke, W A; Stiller, R L; Rose, M E

    1995-10-01

    Nitrous oxide (N2O), 70%, in O2 is often used as a control condition after surgical preparation in rodents undergoing neuroscience investigations. Concern has been expressed that this constitutes a stressful condition. Microdialysis was used in 15 rats to assess extracellular striatal dopamine concentrations during overnight soundproof isolation and on the following day after vascular cannulation and halothane excretion under N2O sedation with concomitant neuromuscular blockade. The overnight dialysate dopamine concentration was 22.8 +/- 8.7 pg/40 microliters. Thirty minutes after stopping halothane, the dialysate concentration was 362.6 +/- 91.6 pg/40 microliters during postsurgical N2O sedation. These data indicate that (a) compared to an unstressed baseline, significant brain dopamine effects occur with N2O sedation after surgery with halothane N2O anesthesia, and (b) baseline conditions can have a major effect on microdialysis data expressed as percentage of baseline.

  16. The position dependent 15N enrichment of nitrous oxide in the stratosphere.

    PubMed

    Röckmann, T; Kaiser, J; Brenninkmeijer, C A; Brand, W A; Borchers, R; Crowley, J N; Wollenhaupt, M; Crutzen, P J

    2001-01-01

    The position dependent 15N fractionation of nitrous oxide (N2O), which cannot be obtained from mass spectrometric analysis on molecular N2O itself, can be determined with high precision using isotope ratio mass spectrometry on the NO+ fragment that is formed on electron impact in the source of an isotope ratio mass spectrometer. Laboratory UV photolysis experiments show that strong position dependent 15N fractionations occur in the photolysis of N2O in the stratosphere, its major atmospheric sink. Measurements on the isotopic composition of stratospheric N2O indeed confirm the presence of strong isotope enrichments, in particular the difference in the fractionation constants for 15N14NO and 14N15NO. The absolute magnitudes of the fractionation constants found in the stratosphere are much smaller, however, than those found in the lab experiments, demonstrating the importance of dynamical and also additional chemical processes like the reaction of N2O with O(1D).

  17. Climate change reduces warming potential of nitrous oxide by an enhanced Brewer-Dobson circulation

    NASA Astrophysics Data System (ADS)

    Kracher, Daniela; Reick, Christian H.; Manzini, Elisa; Schultz, Martin G.; Stein, Olaf

    2016-06-01

    The Brewer-Dobson circulation (BDC), which is an important driver of the stratosphere-troposphere exchange, is expected to accelerate with climate change. One particular consequence of this acceleration is the enhanced transport of nitrous oxide (N2O) from its sources at the Earth's surface toward its main sink region in the stratosphere, thus inducing a reduction in its lifetime. N2O is a potent greenhouse gas and the most relevant currently emitted ozone-depleting substance. Here we examine the implications of a reduced N2O lifetime in the context of climate change. We find a decrease in its global warming potential (GWP) and, due to a decline in the atmospheric N2O burden, also a reduction in its total radiative forcing. From the idealized transient global warming simulation we can identify linear regressions for N2O sink, lifetime, and GWP with temperature rise. Our findings are thus not restricted to a particular scenario.

  18. An inexpensive automatic sampler with static chambers for nitrous oxide emission measurement

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Static flux chambers are often used to determine emission flux of gases such as greenhouse gas nitrous oxide (N2O). However, the sampling process is laborious especially when many treatments/plots are included to compare treatment effects in the effort to develop mitigation strategies. To solve this...

  19. NITROUS OXIDE BEHAVIOR IN THE ATMOSPHERE, AND IN COMBUSTION AND INDUSTRIAL SYSTEMS

    EPA Science Inventory

    Tropospheric measurements show that nitrous oxide (N2O) concentrations are increasing over time. This demonstrates the existence of one or more significant anthropogenic sources, a fact that has generated considerable research interest over the last several years. The debate has ...

  20. Nitrous oxide, methane emission, and yield-scaled emission from organically and conventionally managed systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is a gap in empirical greenhouse gas (GHG) data from many regions of the USA including the northern Corn Belt. This study compared nitrous oxide (N2O) emission in diverse, low-tillage conventionally- and organically-managed systems. Both systems had a four-year rotation, mole-knife, strip till...

  1. Marine nitrous oxide emissions: An unknown liability for the international water sector

    EPA Science Inventory

    Reliable estimates of anthropogenic greenhouse gas (GHG) emissions are essential for setting effective climate policy at both the sector and national level. Current IPCC Guidelines for calculating nitrous oxide (N2O) emissions from sewage management are both highly uncertain and ...

  2. Ammonia and nitrous oxide model for open lot cattle production systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Air emissions, such as ammonia (NH3) and nitrous oxide (N2O), vary considerably among beef and dairy open lot operations as influenced by the climate and manure pack conditions. Because of the challenges with direct measurements, process-based modeling is a recommended approach for estimating air em...

  3. Nitrogen Source Effects on Soil Nitrous Oxide Emissions from No-Till Corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of N fertilizer source on soil nitrous oxide (N2O) emissions from a no-till, irrigated continuous corn field was evaluated near Fort Collins, CO in 2009 and 2010. Five N sources (urea, ESN, SuperU, UAN, UAN+AgrotainPlus) were surface band applied at 202 kg N/ha at corn emergence, includi...

  4. Nitrogen Source Effects on Nitrous Oxide Emissions from a Strip-Tilled Corn Field

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effects of N source on nitrous oxide (N2O) emissions from a strip-till, irrigated continuous corn field was evaluated near Fort Collins, CO. Six N fertilizer sources (urea, ESN, SuperU, UAN, UAN+AgrotainPlus, UAN+Nfusion) were surface band applied at 202 kg N/ha near the corn row at corn emerge...

  5. EPA/IFP EUROPEAN WORKSHOP ON THE EMISSION ON NITROUS OXIDE FROM FOSSIL FUEL COMBUSTION

    EPA Science Inventory

    The report summarizes the proceedings of an EPA/Institut Francais du Petrole (IFP) cosponsored workshop addressing direct nitrous oxide (N2O) emission from fossil fuel combustion. The third in a series, it was held at the IFP in Rueil-Malmaison, France, on June 1-2, 1988. Increas...

  6. Nitrogen placement effects on soil nitrous oxide emissions from irrigated corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Limited information is available on how N fertilizer placement affects soil nitrous oxide (N2O) emissions under irrigated conditions in the semi-arid western U.S. Our objective was to evaluate the effects of surface banding (applied near corn row) and broadcasting of three N sources (urea, polymer...

  7. Accuracy and Precision Analysis of Chamber-Based Nitrous Oxide Gas Flux Estimates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chamber-based estimates of soil-to-atmosphere nitrous oxide (N2O) gas flux tend to underestimate actual emission rates due to inherently non-linear time series data. In theory, this limitation can be minimized by adjusting measurement conditions to reduce non-linearity and/or by using flux-calculati...

  8. Theoretical comparison of advanced methods for calculating nitrous oxide fluxes using non-steady state chambers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several flux-calculation (FC) schemes are available for determining soil-to-atmosphere emissions of nitrous oxide (N2O) and other trace gases using data from non-steady-state flux chambers. Recently developed methods claim to provide more accuracy in estimating the true pre-deployment flux (f0) comp...

  9. Mitigation of methane and nitrous oxide emissions from animal operations: A review of manure management options

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This review analyzes published data on manure management practices used to mitigate methane (CH4) and nitrous oxide (N2O) emissions from animal operations. This is the second in a series of reports commissioned by the Food and Agriculture Organization of the United Nations to evaluate mitigation pra...

  10. RECOMMENDED OPERATING PROCEDURE NO. 45: ANALYSIS OF NITROUS OXIDE FROM COMBUSTION SOURCES

    EPA Science Inventory

    The recommended operating procedure (ROP) has been prepared for use in research activities conducted by EPA's Air and Energy Engineering Research Laboratory (AEERL). he procedure applies to the measurement of nitrous oxide (N2O) in dry gas samples extracted from gas streams where...

  11. A review of nitrous oxide mitigation by farm nitrogen management in temperate grassland-based agriculture.

    PubMed

    Li, Dejun; Watson, Catherine J; Yan, Ming Jia; Lalor, Stan; Rafique, Rashid; Hyde, Bernard; Lanigan, Gary; Richards, Karl G; Holden, Nicholas M; Humphreys, James

    2013-10-15

    Nitrous oxide (N2O) emission from grassland-based agriculture is an important source of atmospheric N2O. It is hence crucial to explore various solutions including farm nitrogen (N) management to mitigate N2O emissions without sacrificing farm profitability and food supply. This paper reviews major N management practices to lower N2O emission from grassland-based agriculture. Restricted grazing by reducing grazing time is an effective way to decrease N2O emissions from excreta patches. Balancing the protein-to-energy ratios in the diets of ruminants can also decrease N2O emissions from excreta patches. Among the managements of synthetic fertilizer N application, only adjusting fertilizer N rate and slow-released fertilizers are proven to be effective in lowering N2O emissions. Use of bedding materials may increase N2O emissions from animal houses. Manure storage as slurry, manipulating slurry pH to values lower than 6 and storage as solid manure under anaerobic conditions help to reduce N2O emissions during manure storage stage. For manure land application, N2O emissions can be mitigated by reducing manure N inputs to levels that satisfy grass needs. Use of nitrification inhibitors can substantially lower N2O emissions associated with applications of fertilizers and manures and from urine patches. N2O emissions from legume based grasslands are generally lower than fertilizer-based systems. In conclusion, effective measures should be taken at each step during N flow or combined options should be used in order to mitigate N2O emission at the farm level.

  12. The structure of the O2-N2O complex.

    PubMed

    Salmon, Steven R; Lane, Joseph R

    2015-09-28

    We have investigated the lowest energy structures and interaction energies of the oxygen nitrous oxide complex (O2-N2O) using explicitly correlated coupled cluster theory. We find that the intermolecular potential energy surface of O2-N2O is very flat, with two minima of comparable energy separated by a low energy first order saddle point. Our results are able to conclusively distinguish between the two sets of experimental geometric parameters for O2-N2O that were previously determined from rotationally resolved infrared spectra. The global minimum structure of O2-N2O is therefore found to be planar with a distorted slipped parallel structure. Finally, we show that the very flat potential energy surface of O2-N2O is problematic when evaluating vibrational frequencies with a numerical Hessian and that consideration should be given as to whether results might change if the step-size is varied.

  13. Effects of lignite application on ammonia and nitrous oxide emissions from cattle pens.

    PubMed

    Sun, Jianlei; Bai, Mei; Shen, Jianlin; Griffith, David W T; Denmead, Owen T; Hill, Julian; Lam, Shu Kee; Mosier, Arvin R; Chen, Deli

    2016-09-15

    Beef cattle feedlots are a major source of ammonia (NH3) emissions from livestock industries. We investigated the effects of lignite surface applications on NH3 and nitrous oxide (N2O) emissions from beef cattle feedlot pens. Two rates of lignite, 3 and 6kgm(-2), were tested in the treatment pen. No lignite was applied in the control pen. Twenty-four Black Angus steers were fed identical commercial rations in each pen. We measured NH3 and N2O concentrations continuously from 4th Sep to 13th Nov 2014 using Quantum Cascade Laser (QCL) NH3 analysers and a closed-path Fourier Transform Infrared Spectroscopy analyser (CP-FTIR) in conjunction with the integrated horizontal flux method to calculate NH3 and N2O fluxes. During the feeding period, 16 and 26% of the excreted nitrogen (N) (240gNhead(-1)day(-1)) was lost via NH3 volatilization from the control pen, while lignite application decreased NH3 volatilization to 12 and 18% of the excreted N, for Phase 1 and Phase 2, respectively. Compared to the control pen, lignite application decreased NH3 emissions by approximately 30%. Nitrous oxide emissions from the cattle pens were small, 0.10 and 0.14gN2O-Nhead(-1)day(-1) (<0.1% of excreted N) for the control pen, for Phase 1 and Phase 2, respectively. Lignite application increased direct N2O emissions by 40 and 57%, to 0.14 and 0.22gN2O-Nhead(-1)day(-1), for Phase 1 and Phase 2, respectively. The increase in N2O emissions resulting from lignite application was counteracted by the lower indirect N2O emission due to decreased NH3 volatilization. Using 1% as a default emission factor of deposited NH3 for indirect N2O emissions, the application of lignite decreased total N2O emissions.

  14. Differentiating Nitrification and Denitrification Sources of Nitrous Oxide Based on the Isotopomeric Composition

    NASA Astrophysics Data System (ADS)

    Sutka, R. L.; Pitt, A. J.; Ostrom, N. E.; Ostrom, P. H.; Gandhi, H.; Breznak, J.; Bergsma, T.

    2003-12-01

    Atmospheric concentrations of nitrous oxide (N2O) are steadily increasing primarily due to microbial activity in the environment. This has prompted efforts to apportion microbial sources of N2O to specific microbial processes. We investigated the isotopomeric composition N2O as a possible aid in differentiating microbial production mechanisms. Isotopomer refers not only to the isotopic abundance of N2O (δ 15N and δ 18O), but also to the 15N abundance within each of the nitrogen atoms comprising this molecule. In the linear N2O molecule, the central atom is referred to as alpha (α ) and the terminal nitrogen atom is referred to as beta (β ). The site preference refers to the difference between δ 15Nα and δ 15Nβ . We conducted experiments with pure bacterial cultures and agricultural soil mesocosms. Four microbial pathways for the production of N2O were investigated including hydroxylamine oxidation via autotrophic nitrifiers and methane oxidizers and nitrite reduction via denitrifiers and autotrophic nitrifiers. We used concentrated cell suspensions of a nitrifier (Nitrosomonas europaea), a methane oxidizer (Methylococcus capsulatus Bath) and a denitrifier that lacks N2O reductase (Pseudomonas chlororaphis). The average site preference of N2O produced by the oxidation of hydroxylamine by M. capsulatus Bath (5.5 +/- 3.5 per mil) and N. europaea(-2.3 +/- 1.9 per mil) was significantly different. Nitrous oxide produced by the reduction of nitrite by N. europaea and P. chlororaphis had a site preference of -8.3 +/- 3.6 per mil and -8.1 +/- 3.4 per mil, respectively. These results demonstrate that site preference can distinguish N2O produced by hydroxylamine oxidation by two distinct organisms. Furthermore, N2O derived by hydroxylamine oxidation differed significantly from that derived from nitrite reduction by the same nitrifying organism. Soil mesocosm experiments were used to determine that consumption of N2O did not change the isotopomeric composition. Since

  15. Measurement and mitigation of nitrous oxide emissions from a high nitrogen input vegetable system

    NASA Astrophysics Data System (ADS)

    Lam, Shu Kee; Suter, Helen; Davies, Rohan; Bai, Mei; Sun, Jianlei; Chen, Deli

    2015-02-01

    The emission and mitigation of nitrous oxide (N2O) from high nitrogen (N) vegetable systems is not well understood. Nitrification inhibitors are widely used to decrease N2O emissions in many cropping systems. However, most N2O flux measurements and inhibitor impacts have been made with small chambers and have not been investigated at a paddock-scale using micrometeorological techniques. We quantified N2O fluxes over a four ha celery paddock using open-path Fourier Transform Infrared spectroscopy in conjunction with a backward Lagrangian stochastic model, in addition to using a closed chamber technique. The celery crop was grown on a sandy soil in southern Victoria, Australia. The emission of N2O was measured following the application of chicken manure and N fertilizer with and without the application of a nitrification inhibitor 3, 4-dimethyl pyrazole phosphate (DMPP). The two techniques consistently demonstrated that DMPP application reduced N2O emission by 37-44%, even though the N2O fluxes measured by a micrometeorological technique were more than 10 times higher than the small chamber measurements. The results suggest that nitrification inhibitors have the potential to mitigate N2O emission from intensive vegetable production systems, and that the national soil N2O emission inventory assessments and modelling predictions may vary with gas measurement techniques.

  16. Shell biofilm-associated nitrous oxide production in marine molluscs: processes, precursors and relative importance.

    PubMed

    Heisterkamp, Ines M; Schramm, Andreas; Larsen, Lone H; Svenningsen, Nanna B; Lavik, Gaute; de Beer, Dirk; Stief, Peter

    2013-07-01

    Emission of the greenhouse gas nitrous oxide (N2 O) from freshwater and terrestrial invertebrates has exclusively been ascribed to N2 O production by ingested denitrifying bacteria in the anoxic gut of the animals. Our study of marine molluscs now shows that also microbial biofilms on shell surfaces are important sites of N2 O production. The shell biofilms of Mytilus edulis, Littorina littorea and Hinia reticulata contributed 18-94% to the total animal-associated N2 O emission. Nitrification and denitrification were equally important sources of N2 O in shell biofilms as revealed by (15) N-stable isotope experiments with dissected shells. Microsensor measurements confirmed that both nitrification and denitrification can occur in shell biofilms due to a heterogeneous oxygen distribution. Accordingly, ammonium, nitrite and nitrate were important drivers of N2 O production in the shell biofilm of the three mollusc species. Ammonium excretion by the animals was found to be sufficient to sustain N2 O production in the shell biofilm. Apparently, the animals provide a nutrient-enriched microenvironment that stimulates growth and N2 O production of the shell biofilm. This animal-induced stimulation was demonstrated in a long-term microcosm experiment with the snail H. reticulata, where shell biofilms exhibited the highest N2 O emission rates when the animal was still living inside the shell.

  17. Effect of substrate availability on nitrous oxide production by deammonification processes under anoxic conditions.

    PubMed

    Schneider, Yvonne; Beier, Maike; Rosenwinkel, Karl-Heinz

    2012-05-01

    Due to its high global warming potential, nitrous oxide (N(2)O) emissions from wastewater treatment processes have recently received a high degree of attention. Nevertheless, there is still a lack of information regarding the microbiological processes leading to N(2)O production. In this study, two lab-scale sequencing batch reactors were operated with deammonification biomass to investigate the role of denitrification and the influence of substrate availability regarding N(2)O formation during the anoxic phase of deammonification. Three different operational phases were established: within the first phase conversion by anammox was favoured and after a transition phase, denitrification activity was promoted. Low nitrous oxide production was observed during stable operation aiming for anammox conversion. Pulsed inflow of the wastewater containing ammonium (NH(4)(+)) and nitrite (NO(2)(-)) led to increased N(2)O production rates. Within the period of denitrification as dominating nitrogen conversion process, the nitrous oxide concentration level was higher during continuous inflow conditions, but the reaction to pulsed inflow was less pronounced. The results indicated that denitrification was responsible for N(2)O formation from the deammonification biomass. Operational settings to achieve suppression of denitrification processes to a large extend were deducted from the results of the experiments.

  18. Effect of substrate availability on nitrous oxide production by deammonification processes under anoxic conditions

    PubMed Central

    Schneider, Yvonne; Beier, Maike; Rosenwinkel, Karl‐Heinz

    2012-01-01

    Summary Due to its high global warming potential, nitrous oxide (N2O) emissions from wastewater treatment processes have recently received a high degree of attention. Nevertheless, there is still a lack of information regarding the microbiological processes leading to N2O production. In this study, two lab‐scale sequencing batch reactors were operated with deammonification biomass to investigate the role of denitrification and the influence of substrate availability regarding N2O formation during the anoxic phase of deammonification. Three different operational phases were established: within the first phase conversion by anammox was favoured and after a transition phase, denitrification activity was promoted. Low nitrous oxide production was observed during stable operation aiming for anammox conversion. Pulsed inflow of the wastewater containing ammonium (NH4+) and nitrite (NO2‐) led to increased N2O production rates. Within the period of denitrification as dominating nitrogen conversion process, the nitrous oxide concentration level was higher during continuous inflow conditions, but the reaction to pulsed inflow was less pronounced. The results indicated that denitrification was responsible for N2O formation from the deammonification biomass. Operational settings to achieve suppression of denitrification processes to a large extend were deducted from the results of the experiments. PMID:22296600

  19. Measurement system for nitrous oxide based on amperometric gas sensor

    NASA Astrophysics Data System (ADS)

    Siswoyo, S.; Persaud, K. C.; Phillips, V. R.; Sneath, R.

    2017-03-01

    It has been well known that nitrous oxide is an important greenhouse gas, so monitoring and control of its concentration and emission is very important. In this work a nitrous oxide measurement system has been developed consisting of an amperometric sensor and an appropriate lab-made potentiostat that capable measuring picoampere current ranges. The sensor was constructed using a gold microelectrode as working electrode surrounded by a silver wire as quasi reference electrode, with tetraethyl ammonium perchlorate and dimethylsulphoxide as supporting electrolyte and solvent respectively. The lab-made potentiostat was built incorporating a transimpedance amplifier capable of picoampere measurements. This also incorporated a microcontroller based data acquisition system, controlled by a host personal computer using a dedicated computer program. The system was capable of detecting N2O concentrations down to 0.07 % v/v.

  20. Nitrous oxide and oral premedication.

    PubMed

    Giovannitti, J A

    1984-01-01

    Patients frequently require conscious-sedation to achieve anxiety relief in the dental office. There are specific indications, contraindications, advantages, and disadvantages to each sedation modality. Selection of the appropriate anesthetic technique should be individualized for each patient. This paper reviews two important conscious-sedation modalities: oral premedication and nitrous oxide/oxygen inhalation sedation.Pertinent drugs are reviewed and recommendations are made for their use; current researches are presented and new areas for investigation are suggested.

  1. Field-based measurements of gross N2O production in soils using a 15N2O pool dilution technique

    NASA Astrophysics Data System (ADS)

    Yang, W. H.; Teh, Y.; Silver, W. L.

    2011-12-01

    Soils are a major source and sink of nitrous oxide (N2O), a potent greenhouse gas and catalyst for stratospheric ozone depletion. The controls on soil N2O emissions are poorly understood due to the difficulty in measuring gross N2O production and consumption rates. We tested a 15N2O pool dilution technique for simultaneously measuring gross N2O production and consumption rates from soils in the field. Our study site was a managed grassland in the Sacramento-San Joaquin River Delta that exhibited high N2O emissions, averaging 6.4 ± 2.6 mg N m-2 d-1. In the laboratory, gross N2O production and consumption compared well between the 15N2O pool dilution and acetylene inhibition methods whereas the 15NO3- tracer method measured significantly higher rates. In the field, N2O emissions were not significantly affected by increasing chamber headspace concentrations up to 100 ppb 15N2O. The pool dilution model estimates of 14N2O and 15N¬2O concentrations as well as net N2O fluxes fit observed data very well, suggesting that the technique yielded robust estimates of gross N2O production. Gross N2O production rates averaged 8.4 ± 3.2 mg N m-2 d-1 and were most strongly correlated to mineral N concentrations and denitrifying enzyme activity together (R2 = 0.73). Gross N2O consumption rates estimated using the pool dilution technique were 55 ± 1 % less than rates calculated as the difference between gross N2O production rates and net N2O fluxes, possibly due to heterogeneous and/or inadequate 15N2O tracer diffusion to deeper layers in the soil profile. Estimated and calculated gross N2O consumption rates constrained the proportion of produced N2O released to the atmosphere (termed the N2O yield) from 0.70 to 0.84. Gross N2O consumption rates and N2O yields were not strongly correlated to any soil property measured (i.e., soil moisture, pH, DEA, mineral N concentration, soil O2 concentration). Our study demonstrates that the 15N2O pool dilution technique is a valuable tool for

  2. Selective Inhibition of Ammonium Oxidation and Nitrification-Linked N2O Formation by Methyl Fluoride and Dimethyl Ether

    PubMed Central

    Miller, Laurence G.; Coutlakis, M. Denise; Oremland, Ronald S.; Ward, Bess B.

    1993-01-01

    Methyl fluoride (CH3F) and dimethyl ether (DME) inhibited nitrification in washed-cell suspensions of Nitrosomonas europaea and in a variety of oxygenated soils and sediments. Headspace additions of CH3F (10% [vol/vol]) and DME (25% [vol/vol]) fully inhibited NO2- and N2O production from NH4+ in incubations of N. europaea, while lower concentrations of these gases resulted in partial inhibition. Oxidation of hydroxylamine (NH2OH) by N. europaea and oxidation of NO2- by a Nitrobacter sp. were unaffected by CH3F or DME. In nitrifying soils, CH3F and DME inhibited N2O production. In field experiments with surface flux chambers and intact cores, CH3F reduced the release of N2O from soils to the atmosphere by 20- to 30-fold. Inhibition by CH3F also resulted in decreased NO3- + NO2- levels and increased NH4+ levels in soils. CH3F did not affect patterns of dissimilatory nitrate reduction to ammonia in cell suspensions of a nitrate-respiring bacterium, nor did it affect N2O metabolism in denitrifying soils. CH3F and DME will be useful in discriminating N2O production via nitrification and denitrification when both processes occur and in decoupling these processes by blocking NO2- and NO3- production. PMID:16349011

  3. Selective inhibition of ammonium oxidation and nitrification-linked N2O formation by methyl fluoride and dimethyl ether

    USGS Publications Warehouse

    Miller, L.G.; Coutlakis, M.D.; Oremland, R.S.; Ward, B.B.

    1993-01-01

    Methyl fluoride (CH3F) and dimethyl ether (DME) inhibited nitrification in washed-cell suspensions of Nitrosomonas europaea and in a variety of oxygenated soils and sediments. Headspace additions of CH3F (10% [vol/vol]) and DME (25% [vol/vol]) fully inhibited NO2- and N2O production from NH4+ in incubations of N. europaea, while lower concentrations of these gases resulted in partial inhibition. Oxidation of hydroxylamine (NH2OH) by N. europaea and oxidation of NO2- by a Nitrobacter sp. were unaffected by CH3F or DME. In nitrifying soils, CH3F and DME inhibited N2O production. In field experiments with surface flux chambers and intact cores, CH3F reduced the release of N2O from soils to the atmosphere by 20- to 30-fold. Inhibition by CH3F also resulted in decreased NO3- + NO2- levels and increased NH4+ levels in soils. CH3F did not affect patterns of dissimilatory nitrate reduction to ammonia in cell suspensions of a nitrate- respiring bacterium, nor did it affect N2O metabolism in denitrifying soils. CH3F and DME will be useful in discriminating N2O production via nitrification and denitrification when both processes occur and in decoupling these processes by blocking NO2- and NO3- production.

  4. The effects of fire on biogenic soil emissions of nitric oxide and nitrous oxide

    NASA Technical Reports Server (NTRS)

    Levine, Joel S.; Cofer, Wesley R., III; Sebacher, Daniel I.; Boston, Penelope J.; Winstead, Edward L.; Sebacher, Shirley

    1988-01-01

    Measurements of biogenic soil emissions of nitric oxide (NO) and nitrous oxide (N2O) before and after a controlled burn conducted in a chaparral ecosystem on June 22, 1987, showed significantly enhanced emissions of both gases after the burn. Mean NO emissions from heavily burned and wetted (to simulate rainfall) sites exceeded 40 ng N/sq m s, and increase of 2 to 3 compared to preburn wetted site measurements. N2O emissions from burned and wetted sites ranged from 9 to 22 ng N/sq m s. Preburn N2O emissions from these wetted sites were all below the detection level of the instrumentation, indicating a flux below 2 ng N/sq m s. The flux of NO exceeded the N2O flux from burned wetted sites by factors ranging from 2.7 to 3.4. These measurements, coupled with preburn and postburn measurements of ammonium and nitrate in the soil of this chaparral ecosystem and measurements of NO and N2O emissions obtained under controlled laboratory conditions, suggest that the postfire enhancement of NO and N2O emissions is due to production of these gases by nitrifying bacteria.

  5. Anaerobic nitrification-denitrification mediated by Mn-oxides in meso-tidal sediments: Implications for N2 and N2O production

    NASA Astrophysics Data System (ADS)

    Fernandes, Sheryl Oliveira; Javanaud, Cedric; Aigle, Axel; Michotey, Valérie D.; Guasco, Sophie; Deborde, Jonathan; Deflandre, Bruno; Anschutz, Pierre; Bonin, Patricia C.

    2015-04-01

    Field measurements in the Arcachon Bay (southwest France) indicated anaerobic production of NOx via nitrification, which was coupled to the reduction of Mn-oxides. To prove the occurrence of this process, laboratory microcosm experiments were set up. A 15N tracer-based approach was used to track if NOx produced through Mn-oxide-mediated anaerobic nitrification would be reduced to N2 via denitrification or anammox. We also hypothesized the generation of the potent greenhouse gas nitrous oxide (N2O) during nitrification-denitrification in the presence of Mn-oxides. The microcosms were prepared using sediment sectioned at varying depths (0-2.5, 2.5-4.5, 4.5-8.5, 8.5-12 and 12-17 cm) during two sampling campaigns in October (fall) and January (winter). Labeling with 15NO3- revealed low N2 production originating from NO3- in the water column (Pw), which did not increase significantly on amendment with Mn-oxides during both sampling periods. However, for both seasons, a significant increase of N2 produced via nitrification (Pn) was observed upon addition of Mn-oxides reaching 76-fold enhancement at ≤ 2.5 cm. To support these results, sediment slurries of October were subjected to amendment of 15NH4+, 14NO3- with or without addition of Mn-oxides. A substantial production of P15 (N2 production from 15NH4+) within 0-17 cm provided further evidence on nitrification-denitrification mediated by Mn-oxides probably with minimal intervention of anammox. In organically rich sediments, anaerobic nitrification-denitrification mediated by Mn-oxides could play an important role in lowering re-mineralized NH4+ levels in the benthic system. As hypothesized, significant production of N2O through the pathway was observed revealing newer mechanisms leading to the generation of the radiative gas.

  6. Residual effects of fertilization history increase nitrous oxide emissions from zero-N controls:Implications for estimating fertilizer-induced emission factors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural N fertilization is the dominant driver of increasing atmospheric nitrous oxide (N2O) concentrations over the past half century, yet there is considerable uncertainty in estimates of N2O emissions from agriculture. Such estimates are typically based on the amount of N applied and a ferti...

  7. Nitrous oxide emission reduction in temperate biochar-amended soils

    NASA Astrophysics Data System (ADS)

    Felber, R.; Hüppi, R.; Leifeld, J.; Neftel, A.

    2012-01-01

    Biochar, a pyrolysis product of organic residues, is an amendment for agricultural soils to improve soil fertility, sequester CO2 and reduce greenhouse gas (GHG) emissions. In highly weathered tropical soils laboratory incubations of soil-biochar mixtures revealed substantial reductions for nitrous oxide (N2O) and carbon dioxide (CO2). In contrast, evidence is scarce for temperate soils. In a three-factorial laboratory incubation experiment two different temperate agricultural soils were amended with green waste and coffee grounds biochar. N2O and CO2 emissions were measured at the beginning and end of a three month incubation. The experiments were conducted under three different conditions (no additional nutrients, glucose addition, and nitrate and glucose addition) representing different field conditions. We found mean N2O emission reductions of 60 % compared to soils without addition of biochar. The reduction depended on biochar type and soil type as well as on the age of the samples. CO2 emissions were slightly reduced, too. NO3- but not NH4+ concentrations were significantly reduced shortly after biochar incorporation. Despite the highly significant suppression of N2O emissions biochar effects should not be transferred one-to-one to field conditions but need to be tested accordingly.

  8. UK emissions of the greenhouse gas nitrous oxide.

    PubMed

    Skiba, U; Jones, S K; Dragosits, U; Drewer, J; Fowler, D; Rees, R M; Pappa, V A; Cardenas, L; Chadwick, D; Yamulki, S; Manning, A J

    2012-05-05

    Signatories of the Kyoto Protocol are obliged to submit annual accounts of their anthropogenic greenhouse gas emissions, which include nitrous oxide (N(2)O). Emissions from the sectors industry (3.8 Gg), energy (14.4 Gg), agriculture (86.8 Gg), wastewater (4.4 Gg), land use, land-use change and forestry (2.1 Gg) can be calculated by multiplying activity data (i.e. amount of fertilizer applied, animal numbers) with simple emission factors (Tier 1 approach), which are generally applied across wide geographical regions. The agricultural sector is the largest anthropogenic source of N(2)O in many countries and responsible for 75 per cent of UK N(2)O emissions. Microbial N(2)O production in nitrogen-fertilized soils (27.6 Gg), nitrogen-enriched waters (24.2 Gg) and manure storage systems (6.4 Gg) dominate agricultural emission budgets. For the agricultural sector, the Tier 1 emission factor approach is too simplistic to reflect local variations in climate, ecosystems and management, and is unable to take into account some of the mitigation strategies applied. This paper reviews deviations of observed emissions from those calculated using the simple emission factor approach for all anthropogenic sectors, briefly discusses the need to adopt specific emission factors that reflect regional variability in climate, soil type and management, and explains how bottom-up emission inventories can be verified by top-down modelling.

  9. UK emissions of the greenhouse gas nitrous oxide

    PubMed Central

    Skiba, U.; Jones, S. K.; Dragosits, U.; Drewer, J.; Fowler, D.; Rees, R. M.; Pappa, V. A.; Cardenas, L.; Chadwick, D.; Yamulki, S.; Manning, A. J.

    2012-01-01

    Signatories of the Kyoto Protocol are obliged to submit annual accounts of their anthropogenic greenhouse gas emissions, which include nitrous oxide (N2O). Emissions from the sectors industry (3.8 Gg), energy (14.4 Gg), agriculture (86.8 Gg), wastewater (4.4 Gg), land use, land-use change and forestry (2.1 Gg) can be calculated by multiplying activity data (i.e. amount of fertilizer applied, animal numbers) with simple emission factors (Tier 1 approach), which are generally applied across wide geographical regions. The agricultural sector is the largest anthropogenic source of N2O in many countries and responsible for 75 per cent of UK N2O emissions. Microbial N2O production in nitrogen-fertilized soils (27.6 Gg), nitrogen-enriched waters (24.2 Gg) and manure storage systems (6.4 Gg) dominate agricultural emission budgets. For the agricultural sector, the Tier 1 emission factor approach is too simplistic to reflect local variations in climate, ecosystems and management, and is unable to take into account some of the mitigation strategies applied. This paper reviews deviations of observed emissions from those calculated using the simple emission factor approach for all anthropogenic sectors, briefly discusses the need to adopt specific emission factors that reflect regional variability in climate, soil type and management, and explains how bottom-up emission inventories can be verified by top-down modelling. PMID:22451103

  10. Representative concentration pathways and mitigation scenarios for nitrous oxide

    NASA Astrophysics Data System (ADS)

    Davidson, Eric A.

    2012-06-01

    The challenges of mitigating nitrous oxide (N2O) emissions are substantially different from those for carbon dioxide (CO2) and methane (CH4), because nitrogen (N) is essential for food production, and over 80% of anthropogenic N2O emissions are from the agricultural sector. Here I use a model of emission factors of N2O to demonstrate the magnitude of improvements in agriculture and industrial sectors and changes in dietary habits that would be necessary to match the four representative concentration pathways (RCPs) now being considered in the fifth assessment report (AR5) of the Intergovernmental Panel on Climate Change (IPCC). Stabilizing atmospheric N2O by 2050, consistent with the most aggressive of the RCP mitigation scenarios, would require about 50% reductions in emission factors in all sectors and about a 50% reduction in mean per capita meat consumption in the developed world. Technologies exist to achieve such improved efficiencies, but overcoming social, economic, and political impediments for their adoption and for changes in dietary habits will present large challenges.

  11. Variability of Nitrous Oxide Fluxes From West Falmouth Harbor, Cape Cod, Massachusetts

    NASA Astrophysics Data System (ADS)

    Green, A. C.; Crusius, J.; Kroeger, K. D.; Pugh, E. R.; Baldwin, S. M.; Bratton, J. F.

    2008-12-01

    Eutrophic estuaries are potentially important but under-examined sources of the greenhouse gas, nitrous oxide (N2O), to the atmosphere, yet they are also heterogeneous, with potential for N2O discharge from both surface waters and intertidal sediments. In order to investigate the range and variability of N2O fluxes in a nitrogen-enriched estuary, measurements of N2O fluxes were made in West Falmouth Harbor, Massachusetts, during the summer of 2008. West Falmouth Harbor is impacted by increased nitrogen loading through fresh groundwater discharge from upland residential areas and a wastewater treatment plant located within the watershed. Fluxes from intertidal sediments were examined using flux chambers in 42 different sites. These fluxes were highly variable but reached values as high as 3700 μmol N2O/m2/d (average 75 μmol N2O/m2/d). The highest flux measured in West Falmouth Harbor was approximately three orders of magnitude higher than the average flux recently reported for soils, implying that the processes that drive the high fluxes are worthy of attention for understanding controls on fluxes from coastal regions. Results suggest that enhanced N2O fluxes in West Falmouth Harbor may be influenced by the discharge of nitrogen and nitrous oxide-enriched groundwater. N2O concentrations in groundwater ranged from 5-160 times the saturation of nitrous oxide, levels which could drive a flux through surficial sediments. Furthermore, of the sites where visible groundwater discharge was present and resulted in the formation of a pool of fresh groundwater under the flux chamber, 78% produced a significant N2O flux, while only 38% of sites with no visible groundwater discharge produced a detectable N2O flux. Water column N2O fluxes in this location were ~16 μmol N2O/m2/d, assuming a typical estuary gas transfer velocity of 5 cm/hr. Although the intertidal zone contained "hotspots" with very high fluxes, the total flux from the West Falmouth Harbor water column was

  12. Determination of anesthetic molecule environments by infrared spectroscopy. II. Multiple sites for nitrous oxide in proteins, lipids, and brain tissue.

    PubMed

    Hazzard, J H; Gorga, J C; Caughey, W S

    1985-08-01

    The presence of molecules of the general anesthetic nitrous oxide (N2O) in oils, esters, proteins, red cells, cream, lipid vesicles, and brain tissue upon exposure to the gas was observed by infrared spectroscopy. Analysis of the N-N-O antisymmetric stretch band reveals a distribution of N2O molecules among several sites of differing polarity in these solutions and tissues. The sensitivity of the band intensity and frequency to the number and strength of the dipoles in the solvating molecules is demonstrated by the resolution of N2O-ester and N2O-alkane interactions in acetic acid ethyl ester and oleic acid methyl ester. In all aqueous solutions and in all tissues a population of N2O molecules in water is observed. At least two sites of N2O-protein interaction are observed in purified hemoglobin A and packed red cells; multiple N2O sites may also be present in bovine serum albumin. Two sites of N2O-lipid interaction are observed in whipping cream and in an aqueous suspension of phosphatidylcholine vesicles. The sites providing the least polar immediate environment to N2O in hemoglobin, cream, and vesicles give similar band frequencies to those found in pure alkane solvents. Infrared spectra of bovine brain tissue, upon exposure to N2O, show N2O molecules present in water and in two less-polar environments. Analysis of spectra of N2O in cerebellum tissue removed from a dog under halothane-N2O anesthesia reveals, in addition to N2O in water, a single population of N2O molecules in an alkane-like environment. Infrared spectroscopy provides a unique means of probing the structure of the environment of N2O and should prove useful in correlating anesthetic potency with anesthetic environment under physiological conditions.

  13. Plant physiological and soil characteristics associated with methane and nitrous oxide emission from rice paddy.

    PubMed

    Baruah, K K; Gogoi, Boby; Gogoi, P

    2010-01-01

    Methane (CH4) and nitrous oxide (N2O) are important greenhouse gases causing global warming and climate change. Efforts were made to analyze the CH4 and N2O flux in relation to plant and soil factors from rice (Oryza sativa L.) paddy. Ten popularly grown rice varieties namely Rashmisali, Bogajoha, Basmuthi, Lalkalamdani, Choimora (traditional varieties); Mahsuri, Moniram, Kushal, Gitesh and Profulla (high yielding varieties = HYV) were grown during monsoon season of July 2006. The CH4 and N2O emissions were measured the date of transplanting onwards at weekly interval along with soil and plant parameters. The seasonal integrated CH4 and N2O emission (Esif) from rice ranged from 8.13 g m(-2) to 13.00 g m(-2) and 121.63 mg N2O-N m(-2) to 189.46 mg N2O-N m(-2), respectively. Variety Gitesh emitted less N2O and CH4 amongst all the rice varieties. Both CH4 and N2O emission exhibited a significant positive correlation with leaf area, leaf number, tiller number and root dry weight. Soil organic carbon of the experimental field was associated with both CH4 and N2O emission whereas nitrate-N content of soil was associated with N2O emission. Methane emission showed significant positive correlations with soil temperature and crop photosynthetic rate. Traditional rice varieties with profuse vegetative growth recorded higher CH4 and N2O fluxes compared to HYVs. Gitesh and Kushal having low seasonal CH4 and N2O emission with higher yield potential can be recommended as low greenhouse gas emitting rice varieties.

  14. Catalytic conversion of methane to methanol on Cu-SSZ-13 using N2O as oxidant.

    PubMed

    Ipek, B; Lobo, R F

    2016-11-08

    Direct catalytic methanol production from methane is achieved on Cu-SSZ-13 zeolite catalysts using N2O as the oxidant. The methanol production rate on Cu-SSZ-13 (on a per gram basis) was more than twice the rate on Cu-mordenite and more than four times the rate on Cu-ZSM-5.

  15. Decreased N2O reduction by low soil pH causes high N2O emissions in a riparian ecosystem.

    PubMed

    Van den Heuvel, R N; Bakker, S E; Jetten, M S M; Hefting, M M

    2011-05-01

    Quantification of harmful nitrous oxide (N(2)O) emissions from soils is essential for mitigation measures. An important N(2)O producing and reducing process in soils is denitrification, which shows deceased rates at low pH. No clear relationship between N(2)O emissions and soil pH has yet been established because also the relative contribution of N(2)O as the denitrification end product decreases with pH. Our aim was to show the net effect of soil pH on N(2)O production and emission. Therefore, experiments were designed to investigate the effects of pH on NO(3)(-) reduction, N(2)O production and reduction and N(2) production in incubations with pH values set between 4 and 7. Furthermore, field measurements of soil pH and N(2)O emissions were carried out. In incubations, NO(3)(-) reduction and N(2) production rates increased with pH and net N(2)O production rate was highest at pH 5. N(2)O reduction to N(2) was halted until NO(3)(-) was depleted at low pH values, resulting in a built up of N(2)O. As a consequence, N(2)O:N(2) production ratio decreased exponentially with pH. N(2)O reduction appeared therefore more important than N(2)O production in explaining net N(2)O production rates. In the field, a negative exponential relationship for soil pH against N(2)O emissions was observed. Soil pH could therefore be used as a predictive tool for average N(2)O emissions in the studied ecosystem. The occurrence of low pH spots may explain N(2)O emission hotspot occurrence. Future studies should focus on the mechanism behind small scale soil pH variability and the effect of manipulating the pH of soils.

  16. Nitrous Oxide Production in Co- Versus Counter-Diffusion Nitrifying Biofilms

    PubMed Central

    Peng, Lai; Sun, Jing; Liu, Yiwen; Dai, Xiaohu; Ni, Bing-Jie

    2016-01-01

    For the application of biofilm processes, a better understanding of nitrous oxide (N2O) formation within the biofilm is essential for design and operation of biofilm reactors with minimized N2O emissions. In this work, a previously established N2O model incorporating both ammonia oxidizing bacteria (AOB) denitrification and hydroxylamine (NH2OH) oxidation pathways is applied in two structurally different biofilm systems to assess the effects of co- and counter-diffusion on N2O production. It is demonstrated that the diffusion of NH2OH and oxygen within both types of biofilms would form an anoxic layer with the presence of NH2OH and nitrite ( ), which would result in a high N2O production via AOB denitrification pathway. As a result, AOB denitrification pathway is dominant over NH2OH oxidation pathway within the co- and counter-diffusion biofilms. In comparison, the co-diffusion biofilm may generate substantially higher N2O than the counter-diffusion biofilm due to the higher accumulation of NH2OH in co-diffusion biofilm, especially under the condition of high-strength ammonium influent (500 mg N/L), thick biofilm depth (300 μm) and moderate oxygen loading (~1–~4 m3/d). The effect of co- and counter-diffusion on N2O production from the AOB biofilm is minimal when treating low-strength nitrogenous wastewater. PMID:27353382

  17. Nitrous Oxide Production in Co- Versus Counter-Diffusion Nitrifying Biofilms

    NASA Astrophysics Data System (ADS)

    Peng, Lai; Sun, Jing; Liu, Yiwen; Dai, Xiaohu; Ni, Bing-Jie

    2016-06-01

    For the application of biofilm processes, a better understanding of nitrous oxide (N2O) formation within the biofilm is essential for design and operation of biofilm reactors with minimized N2O emissions. In this work, a previously established N2O model incorporating both ammonia oxidizing bacteria (AOB) denitrification and hydroxylamine (NH2OH) oxidation pathways is applied in two structurally different biofilm systems to assess the effects of co- and counter-diffusion on N2O production. It is demonstrated that the diffusion of NH2OH and oxygen within both types of biofilms would form an anoxic layer with the presence of NH2OH and nitrite ( ), which would result in a high N2O production via AOB denitrification pathway. As a result, AOB denitrification pathway is dominant over NH2OH oxidation pathway within the co- and counter-diffusion biofilms. In comparison, the co-diffusion biofilm may generate substantially higher N2O than the counter-diffusion biofilm due to the higher accumulation of NH2OH in co-diffusion biofilm, especially under the condition of high-strength ammonium influent (500 mg N/L), thick biofilm depth (300 μm) and moderate oxygen loading (~1–~4 m3/d). The effect of co- and counter-diffusion on N2O production from the AOB biofilm is minimal when treating low-strength nitrogenous wastewater.

  18. Effects of dissolved oxygen and pH on nitrous oxide production rates in autotrophic partial nitrification granules.

    PubMed

    Rathnayake, Rathnayake M L D; Oshiki, Mamoru; Ishii, Satoshi; Segawa, Takahiro; Satoh, Hisashi; Okabe, Satoshi

    2015-12-01

    The effects of dissolved oxygen (DO) and pH on nitrous oxide (N2O) production rates and pathways in autotrophic partial nitrification (PN) granules were investigated at the granular level. N2O was primarily produced by betaproteobacterial ammonia-oxidizing bacteria, mainly Nitrosomonas europaea, in the oxic surface layer (<200μm) of the autotrophic PN granules. N2O production increased with increasing bulk DO concentration owing to activation of the ammonia (i.e., hydroxylamine) oxidation in this layer. The highest N2O emissions were observed at pH 7.5, although the ammonia oxidation rate was unchanged between pH 6.5 and 8.5. Overall, the results of this study suggest that in situ analyses of PN granules are essential to gaining insight into N2O emission mechanisms in a granule.

  19. Antibiotics and Manure Effects on Microbial Communities Responsible for Nitrous Oxide Emissions from Grasslands

    NASA Astrophysics Data System (ADS)

    Semedo, M.; Song, B.; Sparrer, T.; Crozier, C.; Tobias, C. R.; Phillips, R. L.

    2015-12-01

    Agroecosystems are major contributors of nitrous oxide (N2O) emissions. Denitrification and nitrification are the primary pathways of N2O emission in soils. However, there is uncertainty regarding the organisms responsible for N2O production. Bacteria were previously considered the only microbial N2O source, however, current studies indicate that fungi also produce N2O by denitrification. Denitrifying bacteria can be a source or sink of N2O depending on the presence and expression of nitrous oxide reductase genes (nosZ), encoding for the enzyme converting N2O to N2. Fungal denitrification may produce only N2O as an end product due to missing the nosZ gene. Animal manures applied to agricultural fields can transfer antibiotics to soils as a result of antibiotic use in the livestock industry. These antibiotics target mostly bacteria and may promote fungal growth. The growth inhibition of denitrifying bacteria may favor fungal denitrifiers potentially enhancing N2O emissions. Our objective is to examine the effects of antibiotic exposure and manure fertilization on the microbial communities responsible for N2 and N2O production in grasslands. Soil slurry incubations were conducted with tetracycline at different concentrations. A mesocosm experiment was also performed with soil cores exposed to tetracycline and cow manure. Production of N2O and N2 was measured using gas chromatography with electron capture detector (GC-ECD) and isotope ratio mass spectrometry (IRMS), respectively. Antibiotic inhibition of soil N2 production was found to be dose dependent, reaching up to 80% inhibition with 1g Kg-1 of tetracycline treatment, while N2O production was enhanced up to 8 times. These results suggest higher fungal denitrification with a concomitant decrease in bacterial denitrification after antibiotic exposure. We also found higher N2O fluxes in the soil mesocosms treated with manure plus tetracycline. Quantitative PCR (qPCR) will be conducted to examine the changes in

  20. Role of Si2N2O in the passive oxidation of chemically-vapor-deposited Si3N4

    NASA Technical Reports Server (NTRS)

    Ogbuji, Linus U. J. T.

    1992-01-01

    The results of two-step oxidation experiments on chemically-vapor-deposited Si3N4 and SiC at 1350 C show that a correlation exists between the presence of a Si2N2O interphase and the strong oxidation resistance of Si3N4. During normal oxidation, k sub p for SiC was 15 times higher than that for Si3N4, and the oxide scale on Si3N4 was found by SEM and TEM to contain a prominent Si2N2O inner layer. However, when oxidized samples are annealed in Ar for 1.5 h at 1500 C and reoxidized at 1350 C as before, three things happen: the oxidation k sub p increases over 55-fold for Si3N4, and 3.5-fold for SiC; the Si3N4 and SiC oxidize with nearly equal k sub p's; and, most significantly, the oxide scale on Si3N4 is found to be lacking an inner Si2N2O layer. The implications of this correlation for the competing models of Si3N4 oxidation are discussed.

  1. Fertilizer induced nitrous oxide emissions from Vertisols and Alfisols during sweet sorghum cultivation in the Indian semi-arid tropics.

    PubMed

    Ramu, Karri; Watanabe, Takeshi; Uchino, Hiroshi; Sahrawat, Kanwar L; Wani, Suhas P; Ito, Osamu

    2012-11-01

    Nitrous oxide (N(2)O) emissions from Vertisols and Alfisols during sweet sorghum cultivation in the Indian semi-arid tropics were determined using a closed chamber technique during the rainy season (June-October) of 2010. The study included two treatments, nitrogen (N) at a rate of 90 kg/ha and a control without N fertilizer application. The N(2)O emissions strongly coincided with N fertilization and rainfall events. The cumulative N(2)O-N emission from Alfisols was 1.81 N(2)O-N kg/ha for 90 N treatment and 0.15 N(2)O-N kg/ha for the 0 N treatment. Similarly, the N(2)O-N emission from Vertisols was 0.70 N(2)O-N kg/ha for 90 N treatment and 0.09 N(2)O-N kg/ha for the 0 N treatment. The mean N(2)O-N emission factor for fertilizer induced emissions from the Alfisols was 0.90% as compared to 0.32% for Vertisols. Our results suggest that the N(2)O emissions are dependent on the soil properties. Therefore, the monitoring of N(2)O emissions from different agro-ecological regions, having different soil types, rainfall characteristics, cropping systems and crop management practices are necessary to develop comprehensive and accurate green house gas inventories.

  2. Advances in Instrumentation for Quantification of Isotopic Nitrous Oxide from ppb levels to 100%

    NASA Astrophysics Data System (ADS)

    Dong, F.; Gupta, M.; Leen, J.; Provencal, R. A.; Owano, T. G.; Baer, D. S.

    2013-12-01

    The isotopic composition of trace gases provides information of their origin and fate that cannot be determined from their concentration measurements alone. Biological source and loss processes, like bacterial production of nitrous oxide, are typically accompanied by isotopic selectivity associated with the kinetics of bond formation and destruction. Of the three important biologically mediated greenhouse gases (CO2, CH4 and N2O), the understanding of nitrous oxide isotopic budget in air lags behind the other two gases primarily due to the relatively low concentration of N2O in ambient air (~320 ppb). Furthermore, the origin of nitrates in rivers, lakes, ocean and other water supplies may be determined from analyses of isotopic nitrous oxide produced via chemical reduction or biological conversion. These processes can produce nitrous oxide at levels considerably greater than those present in ambient air. To date, analyses of isotopic nitrous oxide requires either pre-concentration of samples containing low concentrations or dilution of samples with high concentrations. We report significant advances of instrumentation for real-time measurements of site-specific isotopic nitrogen (δ15Nα, δ15Nβ, δ15N, δ18O) and mixing ratio [N2O] of nitrous oxide over a very wide range of mole fractions in air. Specifically, LGR's Isotopic N2O Analyzer can report site-specific isotopic nitrogen and isotopic oxygen continuously in flows ranging from 0.2 to over 20 ppm (parts per million) nitrous oxide in air (with preconcentration or dilution). Furthermore, for samples of limited volume, a batch technique may be used for similar isotopic measurements in discrete samples containing 0.2 ppm to 100% nitrous oxide (e.g., sample volumes from bacterial digestion can be as little as 1-10 mL). This novel technology, which employs cavity enhanced absorption spectroscopy (Off-Axis ICOS) and a mid-infrared laser (4.56 microns) and does not require any cryogenic components, has been

  3. Isotopomeric characterization of nitrous oxide produced by reaction of enzymes extracted from nitrifying and denitrifying bacteria

    NASA Astrophysics Data System (ADS)

    Yamazaki, T.; Hozuki, T.; Arai, K.; Toyoda, S.; Koba, K.; Fujiwara, T.; Yoshida, N.

    2014-05-01

    Nitrous oxide (N2O) is a potent greenhouse gas and produced in denitrification and nitrification by various microorganisms. Site preference (SP) of 15N in N2O, which is defined as the difference in the natural abundance of isotopomers 14N15NO and 15N14NO relative to 14N14NO, has been reported to be a useful tool to quantitatively distinguish N2O production pathways. To determine representative SP values for each microbial process, we firstly measured SP of N2O produced in the enzyme reaction of hydroxylamine oxidoreductase (HAO) purified from two species of ammonia oxidizing bacteria (AOB), Nitrosomonas europaea and Nitrosococcus oceani, and that of nitric oxide reductase (NOR) from Paracoccus denitrificans. The SP value for NOR reaction (-5.9 ± 2.1‰) showed nearly the same value as that reported for N2O produced by P. denitrificans in pure culture. In contrast, SP value for HAO reaction (36.3 ± 2.3‰) was a little higher than the values reported for N2O produced by AOB in aerobic pure culture. Using the SP values obtained by HAO and NOR reactions, we calculated relative contribution of the nitrite (NO2-) reduction (which is followed by NO reduction) to N2O production by N. oceani incubated under different O2 availability. Our calculations revealed that previous in vivo studies might have underestimated the SP value for the NH2OH oxidation pathway possibly due to a small contribution of NO2- reduction pathway. Further evaluation of isotopomer signatures of N2O using common enzymes of other processes related to N2O would improve the isotopomer analysis of N2O in various environments.

  4. Isotopomeric characterization of nitrous oxide produced by reaction of enzymes extracted from nitrifying and denitrifying bacteria

    NASA Astrophysics Data System (ADS)

    Yamazaki, T.; Hozuki, T.; Arai, K.; Toyoda, S.; Koba, K.; Fujiwara, T.; Yoshida, N.

    2013-10-01

    Nitrous oxide (N2O) is a potent greenhouse gas and produced in denitrification and nitrification in environmental nitrogen cycle by various microorganism. Site preference (SP) of 15N in N2O, which is defined as the difference in the natural abundance of isotopomers 14N15NO and 15N14NO relative to 14N14NO, has been reported to be a useful tool to quantitatively distinguish N2O production pathway. To determine representative SP value for each microbial process, we firstly measured SP of N2O produced in the enzyme reaction of hydroxylamine oxidoreductase (HAO) purified from two species of ammonia oxidizing bacteria (AOB), Nitrosomonas europaea and Nitrosococcus oceani, and that of nitric oxide reductase (NOR) from Paracoccus denitrificans, respectively. The SP value for NOR reaction (-5.9 ± 2.1‰) showed nearly the same value as that reported for N2O produced by P. denitrificans in pure culture. In contrast, SP value for HAO reaction (36.3 ± 2.3‰) was a little higher than the values reported for N2O produced by AOB in aerobic pure culture. Using the SP values obtained by HAO and NOR reactions, we calculated relative contribution of the nitrite (NO2-) reduction (which is followed by NO reduction) to N2O production by N. oceani incubated under different O2 availability. Our calculations revealed that previous in vivo studies might have underestimated the SP value for NH2OH oxidation pathway possibly due to a small contribution of NO2- reduction pathway. Further evaluation of isotopomer signatures of N2O using common enzymes of other processes related to N2O would improve the isotopomer analysis of N2O in various environments.

  5. Nitrous Oxide Metabolism in Nitrate-Reducing Bacteria: Physiology and Regulatory Mechanisms.

    PubMed

    Torres, M J; Simon, J; Rowley, G; Bedmar, E J; Richardson, D J; Gates, A J; Delgado, M J

    2016-01-01

    Nitrous oxide (N2O) is an important greenhouse gas (GHG) with substantial global warming potential and also contributes to ozone depletion through photochemical nitric oxide (NO) production in the stratosphere. The negative effects of N2O on climate and stratospheric ozone make N2O mitigation an international challenge. More than 60% of global N2O emissions are emitted from agricultural soils mainly due to the application of synthetic nitrogen-containing fertilizers. Thus, mitigation strategies must be developed which increase (or at least do not negatively impact) on agricultural efficiency whilst decrease the levels of N2O released. This aim is particularly important in the context of the ever expanding population and subsequent increased burden on the food chain. More than two-thirds of N2O emissions from soils can be attributed to bacterial and fungal denitrification and nitrification processes. In ammonia-oxidizing bacteria, N2O is formed through the oxidation of hydroxylamine to nitrite. In denitrifiers, nitrate is reduced to N2 via nitrite, NO and N2O production. In addition to denitrification, respiratory nitrate ammonification (also termed dissimilatory nitrate reduction to ammonium) is another important nitrate-reducing mechanism in soil, responsible for the loss of nitrate and production of N2O from reduction of NO that is formed as a by-product of the reduction process. This review will synthesize our current understanding of the environmental, regulatory and biochemical control of N2O emissions by nitrate-reducing bacteria and point to new solutions for agricultural GHG mitigation.

  6. Nitrate and dissolved nitrous oxide in groundwater within cropped fields and riparian buffers

    NASA Astrophysics Data System (ADS)

    Kim, D.-G.; Isenhart, T. M.; Parkin, T. B.; Schultz, R. C.; Loynachan, T. E.

    2009-01-01

    Transport and fate of dissolved nitrous oxide (N2O) in groundwater and its significance to nitrogen dynamics within agro-ecosystems are poorly known in spite of significant potential of N2O to global warming and ozone depletion. Increasing denitrification in riparian buffers may trade a reduction in nitrate (NO3-) transport to surface waters for increased N2O emissions resulting from denitrification-produced N2O dissolved in groundwater being emitted into the air when groundwater flows into a stream or a river. This study quantifies the transport and fate of NO3- and dissolved N2O moving from crop fields through riparian buffers, assesses whether groundwater exported from crop fields and riparian buffers is a significant source of dissolved N2O emissions, and evaluates the Intergovernmental Panel on Climate Change (IPCC) methodology to estimate dissolved N2O emission. We measured concentrations of NO3-; chloride (Cl-); pH; dissolved N2O, dissolved oxygen (DO), and organic carbon (DOC) in groundwater under a multi-species riparian buffer, a cool-season grass filter, and adjacent crop fields located in the Bear Creek watershed in central Iowa, USA. In both the multi-species riparian buffer and the cool-season grass filter, concentrations of dissolved N2O in the groundwater did not change as it passed through the sites, even when the concentrations of groundwater NO3- were decreased by 50% and 59%, respectively, over the same periods. The fraction of N lost to leaching and runoff (0.05) and the modified N2O emission factor, [ratio of dissolved N2O flux to N input (0.00002)] determined for the cropped fields indicate that the current IPCC methodology overestimates dissolved N2O flux in the sites. A low ratio between dissolved N2O flux and soil N2O emission (0.0003) was estimated in the cropped fields. These results suggest that the riparian buffers established adjacent to crop fields for water quality functions (enhanced denitrification) decreased NO3- and were not a

  7. Nitrous oxide measurements during EIFEX, the European Iron Fertilization Experiment in the subpolar South Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Walter, Sylvia; Peeken, Ilka; Lochte, Karin; Webb, Adrian; Bange, Hermann W.

    2005-12-01

    We measured the vertical water column distribution of nitrous oxide (N2O) during the European Iron Fertilization Experiment (EIFEX) in the subpolar South Atlantic Ocean during February/March 2004 (R/V Polarstern cruise ANT XXI/3). Despite a huge build-up and sedimentation of a phytoplankton bloom, a comparison of the N2O concentrations within the fertilized patch with concentrations measured outside the fertilized patch revealed no N2O accumulation within 33 days. This is in contrast to a previous study in the Southern Ocean, where enhanced N2O accumulation occurred in the pycnocline. Thus, we conclude that Fe fertilization does not necessarily trigger additional N2O formation and we caution that a predicted radiative offset due to a Fe-induced additional release of oceanic N2O might be overestimated. Rapid sedimentation events during EIFEX might have hindered the build-up of N2O and suggest, that not only the production of phytoplankton biomass but also its pathway in the water column needs to be considered if N2O radiative offset is modeled.

  8. [Nitrous oxide emissions from municipal solid waste landfills and its measuring methodology: a review].

    PubMed

    Jia, Ming-Sheng; Wang, Xiao-Jun; Chen, Shao-Hua

    2014-06-01

    Nitrous oxide (N2O) is one of three major greenhouse gases and the dominant ozone-depleting substance. Landfilling is the major approach for the treatment and disposal of municipal solid waste (MSW), while MSW landfills can be an important anthropogenic source for N2O emissions. Measurements at lab-scale and full-scale landfills have demonstrated that N2O can be emitted in substantial amounts in MSW landfills; however, a large variation in reported emission values exists. Currently, the mechanisms of N2O production and emission in landfills and its contribution to global warming are still lack of sufficient studies. Meanwhile, obtaining reliable N2O fluxes data in landfills remains a question with existing in-situ measurement techniques. This paper summarized relevant literature data on this issue and analyzed the potential production and emission mechanisms of N2O in traditional anaerobic sanitary landfill by dividing it into the MSW buried and the cover soil. The corresponding mechanisms in nitrogen removal bioreactor landfills were analyzed. Finally, the applicability of existing in-situ approaches measuring N2O fluxes in landfills, such as chamber and micrometeorological methods, was discussed and areas in which further research concerning N2O emissions in landfills was urgently required were proposed as well.

  9. Neglecting diurnal variations leads to uncertainties in terrestrial nitrous oxide emissions.

    PubMed

    Shurpali, Narasinha J; Rannik, Üllar; Jokinen, Simo; Lind, Saara; Biasi, Christina; Mammarella, Ivan; Peltola, Olli; Pihlatie, Mari; Hyvönen, Niina; Räty, Mari; Haapanala, Sami; Zahniser, Mark; Virkajärvi, Perttu; Vesala, Timo; Martikainen, Pertti J

    2016-05-09

    Nitrous oxide (N2O) is an important greenhouse gas produced in soil and aquatic ecosystems. Its warming potential is 296 times higher than that of CO2. Most N2O emission measurements made so far are limited in temporal and spatial resolution causing uncertainties in the global N2O budget. Recent advances in laser spectroscopic techniques provide an excellent tool for area-integrated, direct and continuous field measurements of N2O fluxes using the eddy covariance method. By employing this technique on an agricultural site with four laser-based analysers, we show here that N2O exchange exhibits contrasting diurnal behaviour depending upon soil nitrogen availability. When soil N was high due to fertilizer application, N2O emissions were higher during daytime than during the night. However, when soil N became limited, emissions were higher during the night than during the day. These reverse diurnal patterns supported by isotopic analyses may indicate a dominant role of plants on microbial processes associated with N2O exchange. This study highlights the potential of new technologies in improving estimates of global N2O sources.

  10. Neglecting diurnal variations leads to uncertainties in terrestrial nitrous oxide emissions

    PubMed Central

    Shurpali, Narasinha J.; Rannik, Üllar; Jokinen, Simo; Lind, Saara; Biasi, Christina; Mammarella, Ivan; Peltola, Olli; Pihlatie, Mari; Hyvönen, Niina; Räty, Mari; Haapanala, Sami; Zahniser, Mark; Virkajärvi, Perttu; Vesala, Timo; Martikainen, Pertti J.

    2016-01-01

    Nitrous oxide (N2O) is an important greenhouse gas produced in soil and aquatic ecosystems. Its warming potential is 296 times higher than that of CO2. Most N2O emission measurements made so far are limited in temporal and spatial resolution causing uncertainties in the global N2O budget. Recent advances in laser spectroscopic techniques provide an excellent tool for area-integrated, direct and continuous field measurements of N2O fluxes using the eddy covariance method. By employing this technique on an agricultural site with four laser-based analysers, we show here that N2O exchange exhibits contrasting diurnal behaviour depending upon soil nitrogen availability. When soil N was high due to fertilizer application, N2O emissions were higher during daytime than during the night. However, when soil N became limited, emissions were higher during the night than during the day. These reverse diurnal patterns supported by isotopic analyses may indicate a dominant role of plants on microbial processes associated with N2O exchange. This study highlights the potential of new technologies in improving estimates of global N2O sources. PMID:27158119

  11. Neglecting diurnal variations leads to uncertainties in terrestrial nitrous oxide emissions

    NASA Astrophysics Data System (ADS)

    Shurpali, Narasinha J.; Rannik, Üllar; Jokinen, Simo; Lind, Saara; Biasi, Christina; Mammarella, Ivan; Peltola, Olli; Pihlatie, Mari; Hyvönen, Niina; Räty, Mari; Haapanala, Sami; Zahniser, Mark; Virkajärvi, Perttu; Vesala, Timo; Martikainen, Pertti J.

    2016-05-01

    Nitrous oxide (N2O) is an important greenhouse gas produced in soil and aquatic ecosystems. Its warming potential is 296 times higher than that of CO2. Most N2O emission measurements made so far are limited in temporal and spatial resolution causing uncertainties in the global N2O budget. Recent advances in laser spectroscopic techniques provide an excellent tool for area-integrated, direct and continuous field measurements of N2O fluxes using the eddy covariance method. By employing this technique on an agricultural site with four laser-based analysers, we show here that N2O exchange exhibits contrasting diurnal behaviour depending upon soil nitrogen availability. When soil N was high due to fertilizer application, N2O emissions were higher during daytime than during the night. However, when soil N became limited, emissions were higher during the night than during the day. These reverse diurnal patterns supported by isotopic analyses may indicate a dominant role of plants on microbial processes associated with N2O exchange. This study highlights the potential of new technologies in improving estimates of global N2O sources.

  12. Nitrosomonas europaea cytochrome P460 is a direct link between nitrification and nitrous oxide emission.

    PubMed

    Caranto, Jonathan D; Vilbert, Avery C; Lancaster, Kyle M

    2016-12-20

    Ammonia oxidizing bacteria (AOB) are major contributors to the emission of nitrous oxide (N2O). It has been proposed that N2O is produced by reduction of NO. Here, we report that the enzyme cytochrome (cyt) P460 from the AOB Nitrosomonas europaea converts hydroxylamine (NH2OH) quantitatively to N2O under anaerobic conditions. Previous literature reported that this enzyme oxidizes NH2OH to nitrite ([Formula: see text]) under aerobic conditions. Although we observe [Formula: see text] formation under aerobic conditions, its concentration is not stoichiometric with the NH2OH concentration. By contrast, under anaerobic conditions, the enzyme uses 4 oxidizing equivalents (eq) to convert 2 eq of NH2OH to N2O. Enzyme kinetics coupled to UV/visible absorption and electron paramagnetic resonance (EPR) spectroscopies support a mechanism in which an Fe(III)-NH2OH adduct of cyt P460 is oxidized to an {FeNO}(6) unit. This species subsequently undergoes nucleophilic attack by a second equivalent of NH2OH, forming the N-N bond of N2O during a bimolecular, rate-determining step. We propose that [Formula: see text] results when nitric oxide (NO) dissociates from the {FeNO}(6) intermediate and reacts with dioxygen. Thus, [Formula: see text] is not a direct product of cyt P460 activity. We hypothesize that the cyt P460 oxidation of NH2OH contributes to NO and N2O emissions from nitrifying microorganisms.

  13. Al- or Si-decorated graphene oxide: A favorable metal-free catalyst for the N2O reduction

    NASA Astrophysics Data System (ADS)

    Esrafili, Mehdi D.; Sharifi, Fahimeh; Nematollahi, Parisa

    2016-11-01

    The structural and catalytic properties of Al- or Si-decorated graphene oxide (Al-/Si-GO) are studied by means of density functional theory calculations. The relatively large adsorption energy together with the small Alsbnd O or Sisbnd O binding distances indicate that the epoxy groups over the GO surface can strongly stabilize the single Al or Si atom. Hence, Al-GO and Si-GO are stable enough to be utilized in catalytic reduction of N2O by CO molecule. It is found that the adsorption and decomposition of N2O molecule over Si-GO is more favorable than over Al-GO, due to its larger adsorption energy (Eads) and charge transfer (qCT) values. On the other hand, the CO molecule is physically adsorbed over both surfaces, with relatively small Eads and qCT values. Therefore, at the presence of N2O and CO molecules as the reaction gas, the Al or Si atom of the surface should be dominantly covered by N2O molecule. Our results indicate that the N2O decomposition process can take place with a negligible activation energy over Al-/Si-GO surface, where the N2 molecule can be easily released from the surface. Then, the activated oxygen atom (Oads) which remains over the surface reacts with the CO molecule to form the CO2 molecule via the reaction Oads + CO → CO2. Based on the calculated activation energies, it is suggested that both Al-GO and Si-GO can be used as an efficient metal-free catalyst for the reduction of N2O molecule at ambient conditions.

  14. Effect of Alcaligenes faecalis on nitrous oxide emission and nitrogen removal in three phase fluidized bed process.

    PubMed

    Kim, Jeong-Sook; Kim, Shi-Jun; Lee, Byung-Hun

    2004-01-01

    Nitrous oxide (N2O), one of the greenhouse effect gases, has not been known that how much N2O is produced from municipal wastewater treatment and what its management should be. In this study, for controlling nitrous oxide emission and removing nitrogen from municipal wastewater, we experimented the three phase fluidized bed process equipped with draft tube along with immobilized Alcaligenes faecalis, a typical heterotrophic nitrifer and a predominant genus. Also we evaluated the optimum treatment condition of the three phase fluidized bed process for emitting nitrous oxide. The results of this study showed that the three phase fluidized bed process was more effective than the activated sludge process for controlling nitrous oxide emission and removing nitrogen. Increasing amount of A. faecalis in reactor should be encouraged for controlling nitrous oxide emission and removing nitrogen. In addition, the activated sludge process using immobilized A. faecalis as a carrier had more nitrogen removal efficiency than conventional activated sludge process. The accumulation of NO2-N, NO3-N resulted in high N2O emission. Therefore, we suggested that it is necessary to reduce NO2-N and NO3-N for both reducing N2O emission and improving nitrogen removal.

  15. N2O reduction by the mu4-sulfide-bridged tetranuclear CuZ cluster active site.

    PubMed

    Chen, Peng; Gorelsky, Serge I; Ghosh, Somdatta; Solomon, Edward I

    2004-08-13

    Nitrous oxide (N2O) reduction is a chemical challenge both in the selective oxidation of organic substrates by N2O and in the removal of N2O as a green-house gas. The reduction of N2O is thermodynamically favorable but kinetically inert, and requires activating transition-metal centers. In biological systems, N2O reduction is the last step in the denitrification process of the bacterial nitrogen cycle and is accomplished by the enzyme nitrous oxide reductase, whose active site consists of a micro4-sulfide-bridged tetranuclear CuZ cluster which has many unusual spectroscopic features. Recent studies have developed a detailed electronic-structure description of the resting CuZ cluster, determined its catalytically relevant state, and provided insight into the role of this tetranuclear copper cluster in N2O activation and reduction.

  16. Sources of variation in nitrous oxide flux from Amazonian ecosystems

    NASA Technical Reports Server (NTRS)

    Matson, P. A.; Vitousek, P. M.; Livingston, G. P.; Swanberg, N. A.

    1990-01-01

    Nitrous oxide flux and soil nutrient characteristics were measured in three undisturbed tropical ecosystem types, in cleared and burned areas, and in areas of forest converted to pasture near Manaus, Brazil. Nitrogen mineralization, nitrification, and soil nitrogen pools were high in upland forests on clay soils (terra firme) and low in the sand-type and floodplain (varzea) soils. Nitrous oxide flux followed the same pattern, with an average flux of 1.9 ng/sq cm per hr in terra firme, 0.3 in sand types, and 0.1 in varzea. Flux from recently cleared and burned areas did not differ from terra firme forest, but pastures had significantly elevated fluxes (10.3 ng/sq cm per hr). These data were combined with satellite data-based areal estimates of land cover classes to estimate total N2O-N flux from the intensive study area used by the Amazon Boundary Layer Experiment. Total N2O-N flux from the area was 22.9 kg/h; pastures covered 11 percent of the area but accounted for over 40 percent of the flux.

  17. Sources of variation in nitrous oxide flux from Amazonian ecosystems

    NASA Astrophysics Data System (ADS)

    Matson, P. A.; Vitousek, P. M.; Livingston, G. P.; Swanberg, N. A.

    1990-09-01

    Nitrous oxide flux and soil nutrient characteristics were measured in three undisturbed tropical ecosystem types, in cleared and burned areas, and in areas of forest converted to pasture near Manaus, Brazil. Nitrogen mineralization, nitrification, and soil nitrogen pools were high in upland forests on clay soils (terra firme) and low in the sand-type and floodplain (varzea) soils. Nitrous oxide flux followed the same pattern, with an average flux of 1.9 ng/sq cm per hr in terra firme, 0.3 in sand types, and 0.1 in varzea. Flux from recently cleared and burned areas did not differ from terra firme forest, but pastures had significantly elevated fluxes (10.3 ng/sq cm per hr). These data were combined with satellite data-based areal estimates of land cover classes to estimate total N2O-N flux from the intensive study area used by the Amazon Boundary Layer Experiment. Total N2O-N flux from the area was 22.9 kg/h; pastures covered 11 percent of the area but accounted for over 40 percent of the flux.

  18. Effectiveness of 2 scavenger mask systems for reducing exposure to nitrous oxide in a hospital-based pediatric dental clinic: a pilot study.

    PubMed

    Freilich, Marshall M; Alexander, Laura; Sándor, George K B; Judd, Peter

    2007-09-01

    Chronic exposure to elevated ambient air levels of nitrous oxide during nitrous oxide/ oxygen (N2O/2) sedation can result in deleterious side effects to dentists and auxiliary staff. A sampling survey was done in the outpatient dental clinic at the Hospital for Sick Children to determine whether airborne nitrous oxide (N2O) gas concentrations were within established regulatory limits. The effectiveness of 2 scavenger mask systems, the Matrix Medical single-mask system and the Porter/Brown double-mask system, for reducing airborne contamination in a clinical environment during the treatment of pediatric dental patients was compared in a pilot study. The results indicated that the double-mask system more effectively minimized N2O exposure during N2O/O2 sedation of outpatients for a variety of clinical pediatric dental procedures.

  19. Nitrous oxide emissions from wetland rice-duck cultivation systems in Southern China.

    PubMed

    Li, Chengfang; Cao, Cougui; Wang, Jingping; Zhan, Ming; Yuan, Weiling; Ahmad, Shahrear

    2009-01-01

    Nitrous oxide (N2O) emissions from a rice-duck cultivation system in the subtropical region of China and its regulating factors were investigated by using a static chambers technique during rice growth seasons in 2006 and 2007. The experimental field was equally divided into six plots for two different treatments: One was a conventional rice field (CK) and the other was a rice-duck ecosystem (RD). With the same amount of urea applied as basal fertilization, N2O emission fluxes from RD and CK followed a similar seasonal variation trend. During the flooding seasons, the N2O emission flux was not correlated with temperature, but it was significantly related to soil inorganic nitrogen (SIN) (p < 0.01) and soil pH (p < 0.01). After drainage, the N2O emission flux was not correlated with temperature, SIN, and soil pH. Our experimental data showed that peaks of N2O emission flux occurred both in 2 weeks after urea application and after drainage. Compared to CK, RD could significantly increase N2O emission. We evaluated the integrated global warming potentials (GWPs) of a rice-duck cultivation system based on methane (CH4) and N2O emission, which showed that RD could suppress the total amount of CH4 and N2O emissions from rice paddies. Moreover, because the decrease of CH4 emissions from RD compared to CK was far more than the increase of N2O emissions from RD compared to CK, RD greatly reduced integrated GWPs (CH4 + N2O) compared to CK. So, the rice-duck cultivation system is an effective strategy for reducing integrated GWPs of the rice-duck cultivation systems based on CH4 and N2O in southern China and will contribute to alleviating global warming.

  20. Estimation of Pre-industrial Nitrous Oxide Emission from the Terrestrial Biosphere

    NASA Astrophysics Data System (ADS)

    Xu, R.; Tian, H.; Lu, C.; Zhang, B.; Pan, S.; Yang, J.

    2015-12-01

    Nitrous oxide (N2O) is currently the third most important greenhouse gases (GHG) after methane (CH4) and carbon dioxide (CO2). Global N2O emission increased substantially primarily due to reactive nitrogen (N) enrichment through fossil fuel combustion, fertilizer production, and legume crop cultivation etc. In order to understand how climate system is perturbed by anthropogenic N2O emissions from the terrestrial biosphere, it is necessary to better estimate the pre-industrial N2O emissions. Previous estimations of natural N2O emissions from the terrestrial biosphere range from 3.3-9.0 Tg N2O-N yr-1. This large uncertainty in the estimation of pre-industrial N2O emissions from the terrestrial biosphere may be caused by uncertainty associated with key parameters such as maximum nitrification and denitrification rates, half-saturation coefficients of soil ammonium and nitrate, N fixation rate, and maximum N uptake rate. In addition to the large estimation range, previous studies did not provide an estimate on preindustrial N2O emissions at regional and biome levels. In this study, we applied a process-based coupled biogeochemical model to estimate the magnitude and spatial patterns of pre-industrial N2O fluxes at biome and continental scales as driven by multiple input data, including pre-industrial climate data, atmospheric CO2 concentration, N deposition, N fixation, and land cover types and distributions. Uncertainty associated with key parameters is also evaluated. Finally, we generate sector-based estimates of pre-industrial N2O emission, which provides a reference for assessing the climate forcing of anthropogenic N2O emission from the land biosphere.

  1. Ab initio intermolecular potential energy surface and thermophysical properties of nitrous oxide

    NASA Astrophysics Data System (ADS)

    Crusius, Johann-Philipp; Hellmann, Robert; Hassel, Egon; Bich, Eckard

    2015-06-01

    We present an analytical intermolecular potential energy surface (PES) for two rigid nitrous oxide (N2O) molecules derived from high-level quantum-chemical ab initio calculations. Interaction energies for 2018 N2O-N2O configurations were computed utilizing the counterpoise-corrected supermolecular approach at the CCSD(T) level of theory using basis sets up to aug-cc-pVQZ supplemented with bond functions. A site-site potential function with seven sites per N2O molecule was fitted to the pair interaction energies. We validated our PES by computing the second virial coefficient as well as shear viscosity and thermal conductivity in the dilute-gas limit. The values of these properties are substantiated by the best experimental data.

  2. Clinical evaluation of the efficacy of three nitrous oxide scavenging units during dental treatment.

    PubMed

    Certosimo, Fred; Walton, Martin; Hartzell, David; Farris, Jennifer

    2002-01-01

    There are environmental health concerns for dental health care providers chronically exposed to trace amounts of waste nitrous oxide (N2O). This study compared the effectiveness of three N2O scavenging systems, the Porter/Brown, the Accutron, and the Matrx, in actual time during use in a standardized mock dental treatment protocol that reflected clinical practice while minimizing the influence of confounding variables. At every occasion during the procedure, the Porter/Brown scavenger system left the operatory with significantly less N2O than any of the other scavengers tested. The Porter/Brown removed between 71% and 91% of the N2O compared to the control (no device).

  3. Measurements of nitrous oxide emissions from vegetable production in China

    NASA Astrophysics Data System (ADS)

    Xiong, Zhengqin; Xie, Yingxin; Xing, Guangxi; Zhu, Zhaoliang; Butenhoff, Chris

    Nitrous oxide (N 2O) emissions resulting from Chinese vegetable production were measured. A site in suburban Nanjing (East coast; Jiangsu Province) was monitored from November 2001 to January 2003, in which five consecutive vegetable crops were sown. The crops consisted of radish, baby bok choy, lettuce, second planting of baby bok choy, and finally celery. Results suggested that N 2O emission events occur in pulses. The average N 2O-N flux for all five crops was 148±9 μg N m -2 h -1 and the average emission rate was 12±0.7 kg N ha -1. The average seasonal emission fluxes ranged from 37 μg N m -2 h -1 in the radish plot to 300 μg N m -2 h -1 in the celery plot. The celery field produced the greatest cumulative emission of 5.8 kg N ha -1 while the baby bok choy field had the lowest rate of 0.96-1.0 kg N ha -1. In total, 0.73% of applied fertilizer N was emitted as N 2O-N as a whole. The lettuce field had the largest emission factor of 2.2%. Results indicate that emissions from vegetable field are a potential source of national N 2O inventory. Temporal variation is much greater than spatial variation and the corresponding CV averaged 115% and 22%, respectively. Under the same total sampling quantity, increasing sampling frequency is more important than increasing spatial replicates.

  4. Microcosm N2O emissions wth calibration

    EPA Pesticide Factsheets

    The dataset consists of measurements of soil nitrous oxide emissions from soils under three different amendments: glucose, cellulose, and manure. Data includes the four isotopomers of nitrous oxide (14N15N16O, 15N14N16O, 14N14N18O, 14N14N16O), and the site preference.This dataset is associated with the following publication:Chen , H., D. Williams , P. Deshmukh , F. Birgand, B. Maxwell, and J. Walker. Probing the Biological Sources of Soil N2O Emissions by Quantum Cascade Laser-Based 15N Isotopocule Analysis. SOIL SCIENCE SOCIETY OF AMERICA JOURNAL. Soil Science Society of America, Madison, WI, USA, 100(0): 175-181, (2016).

  5. Nitrous oxide emission budgets and land-use-driven hotspots for organic soils in Europe

    NASA Astrophysics Data System (ADS)

    Leppelt, T.; Dechow, R.; Gebbert, S.; Freibauer, A.; Lohila, A.; Augustin, J.; Drösler, M.; Fiedler, S.; Glatzel, S.; Höper, H.; Järveoja, J.; Lærke, P. E.; Maljanen, M.; Mander, Ü.; Mäkiranta, P.; Minkkinen, K.; Ojanen, P.; Regina, K.; Strömgren, M.

    2014-12-01

    Organic soils are a main source of direct emissions of nitrous oxide (N2O), an important greenhouse gas (GHG). Observed N2O emissions from organic soils are highly variable in space and time, which causes high uncertainties in national emission inventories. Those uncertainties could be reduced when relating the upscaling process to a priori-identified key drivers by using available N2O observations from plot scale in empirical approaches. We used the empirical fuzzy modelling approach MODE to identify main drivers for N2O and utilize them to predict the spatial emission pattern of European organic soils. We conducted a meta-study with a total amount of 659 annual N2O measurements, which was used to derive separate models for different land use types. We applied our models to available, spatially explicit input driver maps to upscale N2O emissions at European level and compared the inventory with recently published IPCC emission factors. The final statistical models explained up to 60% of the N2O variance. Our study results showed that cropland and grasslands emitted the highest N2O fluxes 0.98 ± 1.08 and 0.58 ± 1.03 g N2O-N m-2 a-1, respectively. High fluxes from cropland sites were mainly controlled by low soil pH value and deep-drained groundwater tables. Grassland hotspot emissions were strongly related to high amount of N-fertilizer inputs and warmer winter temperatures. In contrast, N2O fluxes from natural peatlands were predominantly low (0.07 ± 0.27 g N2O-N m-2 a-1) and we found no relationship with the tested drivers. The total inventory for direct N2O emissions from organic soils in Europe amount up to 149.5 Gg N2O-N a-1, which also included fluxes from forest and peat extraction sites and exceeds the inventory calculated by IPCC emission factors of 87.4 Gg N2O-N a-1. N2O emissions from organic soils represent up to 13% of total European N2O emissions reported in the European Union (EU) greenhouse gas inventory of 2011 from only 7% of the EU area

  6. Annual nitric and nitrous oxide fluxes from Chinese subtropical plastic greenhouse and conventional vegetable cultivations.

    PubMed

    Yao, Zhisheng; Liu, Chunyan; Dong, Haibo; Wang, Rui; Zheng, Xunhua

    2015-01-01

    As intensive vegetable cultivation is rapidly expanding in China and elsewhere worldwide, its environmental consequences on nitrous oxide (N(2)O) and nitric oxide (NO) emissions deserve attention. We measured N(2)O and NO fluxes simultaneously for a full year from Chinese subtropical vegetable fields. Clearly, both N(2)O and NO emissions varied greatly in different vegetable crop seasons within a year, highlighting the importance of whole-year measurement for achieving temporally accurate annual direct emission factors. A revised "hole-in-the-pipe" model well described quantitative relationships between N(2)O plus NO fluxes and soil-specific conditions. Annual background N(2)O and NO emissions were 0.73-5.0 and 0.26-0.56 kg N ha(-1) yr(-1), respectively, for the vegetable cultivations. The farmers' fertilization practice increased N(2)O and NO emissions. Annual direct emission factors for greenhouse and conventional vegetable fields, respectively, were 1.1% and 1.9% for N(2)O, and 0.36% and 0.32% for NO, indicating there is a need to consider a differentiation of emission factors for managed vegetable cultivations.

  7. Nitrous oxide emission from polyculture constructed wetlands: effect of plant species.

    PubMed

    Wang, Yanhua; Inamori, Ryuhei; Kong, Hainan; Xu, Kaiqin; Inamori, Yuhei; Kondo, Takashi; Zhang, Jixiang

    2008-03-01

    Loss of nitrogen from the soil-plant system has raised environmental concern. This study assessed the fluxes of nitrous oxide (N2O) in the subsurface flow constructed wetlands (CWs). To better understand the mechanism of N2O emission, spatial distribution of ammonia-oxidizing bacteria (AOB) in four kinds of wetlands soil were compared. N2O emission data showed large temporal and spatial variation ranging from -5.5 to 32.7 mg N2O m(-2) d(-1). The highest N2O emission occurred in the cell planted with Phragmites australis and Zizania latifolia. Whereas, the lower emission rate were obtained in the cell planted with P. australis and Typha latifolia. These revealed that Z. latifolia stimulated the N2O emission. Transportation of more organic matter and oxygen for AOB growth may be the reason. The study of AOB also supported this result, indicating that the root structure of Z. latifolia was favored by AOB for N2O formation.

  8. Nitrous oxide from moving bed based integrated fixed film activated sludge membrane bioreactors.

    PubMed

    Mannina, Giorgio; Capodici, Marco; Cosenza, Alida; Di Trapani, Daniele; Laudicina, Vito Armando; Ødegaard, Hallvard

    2017-02-01

    The present paper reports the results of a nitrous oxide (N2O) production investigation in a moving bed based integrated fixed film activated sludge (IFAS) membrane bioreactor (MBR) pilot plant designed in accordance with the University of Cape Town layout for biological phosphorous removal. Gaseous and liquid samples were collected in order to measure the gaseous as well as the dissolved concentration of N2O. Furthermore, the gas flow rate from each reactor was measured and the gas flux was estimated. The results confirmed that the anoxic reactor represents the main source of nitrous oxide production. A significant production of N2O was, however, also found in the anaerobic reactor, thus indicating a probable occurrence of the denitrifying phosphate accumulating organism activity. The highest N2O fluxes were emitted from the aerated reactors (3.09 g N2ON m(-2) h(-1) and 9.87 g N2ON m(-2) h(-1), aerobic and MBR tank, respectively). The emission factor highlighted that only 1% of the total treated nitrogen was emitted from the pilot plant. Furthermore, the measured N2O concentrations in the permeate flow were comparable with other reactors. Nitrous oxide mass balances outlined a moderate production also in the MBR reactor despite the low hydraulic retention time. On the other hand, the mass balance showed that in the aerobic reactor a constant consumption of nitrous oxide (up to almost 15 mg N2O h(-1)) took place, due to the high amount of stripped gas.

  9. Mechanisms of inorganic nitrous oxide production in soils during nitrification and their dependence on soil properties

    NASA Astrophysics Data System (ADS)

    Heil, Jannis; Liu, Shurong; Vereecken, Harry; Brüggemann, Nicolas

    2014-05-01

    Nitrous oxide (N2O) is an important anthropogenic greenhouse gas and today's single most ozone depleting substance. Soils have been identified as the major source of N2O. Microbial nitrification and denitrification are considered the major N2O emission sources. However, N2O production in soils, especially during nitrification, is far from being completely understood. Several abiotic reactions involving the nitrification intermediate hydroxylamine (NH2OH) have been identified leading to N2O emissions, but are being neglected in most current studies. However, it is known that NH2OH can be oxidized by several soil constituents to form N2O. For better mitigation strategies it is mandatory to understand the underlying processes of N2O production during nitrification and their controlling factors. We studied N2O emissions from different soils in laboratory incubation experiments. Soils covered a wide range of land use types from arable to grassland and forest. Soil incubations were conducted with and without the addition of NH2OH at conditions favorable for nitrification with non-sterile as well as with sterile samples. N2O and, additionally, CO2 evolution were analyzed using gas chromatography. To get insight into the dynamics of N2O formation, N2O production from NH2OH was quantified online using quantum cascade laser absorption spectroscopy. Furthermore, isotope ratio mass spectrometry was used to analyze the isotopic signature of the produced N2O (i.e. δ15N, δ18O, and 15N site preference). We observed large differences in N2O emissions between different soils upon the addition of NH2OH. While a forest soil sample with pH < 3 showed hardly any reaction to the addition of NH2OH, a very high and immediate formation of N2O was observed in a cropland soil sample at neutral pH. N2O production after NH2OH addition was also observed in autoclaved samples, which confirmed an abiotic production mechanism. Further, isotopic signatures of N2O could be used to differentiate

  10. Evaluation of leachate recirculation on nitrous oxide production in the Likang Landfill, China.

    PubMed

    Lee, Chun Man; Lin, Xue Rui; Lan, Chong Yu; Lo, Samuel Chun Lap; Chan, Gilbert Yuk Sing

    2002-01-01

    Landfill leachate recirculation is efficient in reducing the leachate quantity handled by a leachate treatment plant. However, after land application of leachate, nitrification and denitrification of the ammoniacal N becomes possible and the greenhouse gas nitrous oxide (N2O) is produced. Lack of information on the effects of leachate recirculation on N2O production led to a field study being conducted in the Likang Landfill (Guangzhou, China) where leachate recirculation had been practiced for 8 yr. Monthly productions and fluxes of N2O from leachate and soil were studied from June to November 2000. Environmental and chemical factors regulating N2O production were also accessed. An impermeable top liner was not used at this site; municipal solid waste was simply covered by inert soil and compacted by bulldozers. A high N2O emission rate (113 mg m-2 h-1) was detected from a leachate pond purposely formed on topsoil within the landfill boundary after leachate irrigation. A high N2O level (1.09 micrograms L-1) was detected in a gas sample emitted from topsoil 1 m from the leachate pond. Nitrous oxide production from denitrification in leachate-contaminated soil was at least 20 times higher than that from nitrification based on laboratory incubation studies. The N2O levels emitted from leachate ponds were compared with figures reported for different ecosystems and showed that the results of the present study were 68.7 to 88.6 times higher. Leachate recirculation can be a cost-effective operation in reducing the volume of leachate to be treated in landfill. However, to reduce N2O flux, leachate should be applied to underground soil rather than being irrigated and allowed to flow on topsoil.

  11. Urea Fertilizer Decreases N2O Emissions Compared to Anhydrous Ammonia in Corn Cropping Systems in Minnesota

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantifying nitrous oxide (N2O) emissions from corn and soybean fields under different fertilizer regimes is essential to developing national inventories of greenhouse gas (GHG) emissions. The objective of this study was to compare N2O emissions in plots managed for more than 15 yr under continuous ...

  12. Evaluating four N2O emission algorithms in RZWQM2 in response to N rate on an irrigated corn field

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) emissions from agricultural soils are major contributors to greenhouse gases. Correctly assessing the effects of the interactions between agricultural practices and environmental factors on N2O emissions is required for better crop and nitrogen (N) management. We used an enhanced...

  13. Gas entrapment and microbial N2O reduction reduce N2O emissions from a biochar-amended sandy clay loam soil

    PubMed Central

    Harter, Johannes; Guzman-Bustamante, Ivan; Kuehfuss, Stefanie; Ruser, Reiner; Well, Reinhard; Spott, Oliver; Kappler, Andreas; Behrens, Sebastian

    2016-01-01

    Nitrous oxide (N2O) is a potent greenhouse gas that is produced during microbial nitrogen transformation processes such as nitrification and denitrification. Soils represent the largest sources of N2O emissions with nitrogen fertilizer application being the main driver of rising atmospheric N2O concentrations. Soil biochar amendment has been proposed as a promising tool to mitigate N2O emissions from soils. However, the underlying processes that cause N2O emission suppression in biochar-amended soils are still poorly understood. We set up microcosm experiments with fertilized, wet soil in which we used 15N tracing techniques and quantitative polymerase chain reaction (qPCR) to investigate the impact of biochar on mineral and gaseous nitrogen dynamics and denitrification-specific functional marker gene abundance and expression. In accordance with previous studies our results showed that biochar addition can lead to a significant decrease in N2O emissions. Furthermore, we determined significantly higher quantities of soil-entrapped N2O and N2 in biochar microcosms and a biochar-induced increase in typical and atypical nosZ transcript copy numbers. Our findings suggest that biochar-induced N2O emission mitigation is based on the entrapment of N2O in water-saturated pores of the soil matrix and concurrent stimulation of microbial N2O reduction resulting in an overall decrease of the N2O/(N2O + N2) ratio. PMID:28008997

  14. Gas entrapment and microbial N2O reduction reduce N2O emissions from a biochar-amended sandy clay loam soil

    NASA Astrophysics Data System (ADS)

    Harter, Johannes; Guzman-Bustamante, Ivan; Kuehfuss, Stefanie; Ruser, Reiner; Well, Reinhard; Spott, Oliver; Kappler, Andreas; Behrens, Sebastian

    2016-12-01

    Nitrous oxide (N2O) is a potent greenhouse gas that is produced during microbial nitrogen transformation processes such as nitrification and denitrification. Soils represent the largest sources of N2O emissions with nitrogen fertilizer application being the main driver of rising atmospheric N2O concentrations. Soil biochar amendment has been proposed as a promising tool to mitigate N2O emissions from soils. However, the underlying processes that cause N2O emission suppression in biochar-amended soils are still poorly understood. We set up microcosm experiments with fertilized, wet soil in which we used 15N tracing techniques and quantitative polymerase chain reaction (qPCR) to investigate the impact of biochar on mineral and gaseous nitrogen dynamics and denitrification-specific functional marker gene abundance and expression. In accordance with previous studies our results showed that biochar addition can lead to a significant decrease in N2O emissions. Furthermore, we determined significantly higher quantities of soil-entrapped N2O and N2 in biochar microcosms and a biochar-induced increase in typical and atypical nosZ transcript copy numbers. Our findings suggest that biochar-induced N2O emission mitigation is based on the entrapment of N2O in water-saturated pores of the soil matrix and concurrent stimulation of microbial N2O reduction resulting in an overall decrease of the N2O/(N2O + N2) ratio.

  15. Isotopomer Analysis of N2O Produced During Waste Water Treatment

    NASA Astrophysics Data System (ADS)

    Toyoda, S.; Fujiwara, A.; Yoshida, N.

    2007-12-01

    Nitrous oxide (N2O) is an important trace gas in the atmosphere since it is radiatively active in the troposphere and also a precursor of nitric oxide which catalytically destroys ozone in the stratosphere. Isotopomer ratios (elemental N and O isotope ratios and site-specific N isotope ratios in asymmetric molecule of NNO) have been studied to understand its complex geochemical cycle. Microbial processes such as nitrification and denitrification are the largest N2O sources, and pure culture incubation studies showed that intramolecular 15N-site preference (SP) in N2O can differentiate the two N2O producing processes, hydroxylamine oxidation and nitrite reduction. However, there have been still few studies on N2O isotopomer ratios in complex bacterial systems. In this paper, we investigated the isotopomer ratios in N2O produced in waste water treatment system in order to evaluate characteristics of N2O emitted from human sewage and to understand N2O dynamics in microbial consortia (activated sludge). Water and gas samples were collected step by step in two different treatment systems in a sewage plant in Tokyo. High dissolved N2O concentration (up to 7600%\\ saturation) was observed in biological reaction tanks and isotopomer ratios confirmed active N2O production by microbes. Moreover, isotopomer ratios showed large variations throughout the whole treatment system and suggested that N2O is produced in settling and chlorination steps as well as biological reaction steps.

  16. Nitric oxide and nitrous oxide turnover in natural and engineered microbial communities: biological pathways, chemical reactions, and novel technologies

    PubMed Central

    Schreiber, Frank; Wunderlin, Pascal; Udert, Kai M.; Wells, George F.

    2012-01-01

    Nitrous oxide (N2O) is an environmentally important atmospheric trace gas because it is an effective greenhouse gas and it leads to ozone depletion through photo-chemical nitric oxide (NO) production in the stratosphere. Mitigating its steady increase in atmospheric concentration requires an understanding of the mechanisms that lead to its formation in natural and engineered microbial communities. N2O is formed biologically from the oxidation of hydroxylamine (NH2OH) or the reduction of nitrite (NO−2) to NO and further to N2O. Our review of the biological pathways for N2O production shows that apparently all organisms and pathways known to be involved in the catabolic branch of microbial N-cycle have the potential to catalyze the reduction of NO−2 to NO and the further reduction of NO to N2O, while N2O formation from NH2OH is only performed by ammonia oxidizing bacteria (AOB). In addition to biological pathways, we review important chemical reactions that can lead to NO and N2O formation due to the reactivity of NO−2, NH2OH, and nitroxyl (HNO). Moreover, biological N2O formation is highly dynamic in response to N-imbalance imposed on a system. Thus, understanding NO formation and capturing the dynamics of NO and N2O build-up are key to understand mechanisms of N2O release. Here, we discuss novel technologies that allow experiments on NO and N2O formation at high temporal resolution, namely NO and N2O microelectrodes and the dynamic analysis of the isotopic signature of N2O with quantum cascade laser absorption spectroscopy (QCLAS). In addition, we introduce other techniques that use the isotopic composition of N2O to distinguish production pathways and findings that were made with emerging molecular techniques in complex environments. Finally, we discuss how a combination of the presented tools might help to address important open questions on pathways and controls of nitrogen flow through complex microbial communities that eventually lead to N2O build

  17. Liquid Azide Salts and Their Reactions with Common Oxidizers IRFNA and N2O4 (Postprint)

    DTIC Science & Technology

    2008-01-01

    azides with saturated and unsaturated side chains were prepared and their physical and structural properties were investigated. The reactivity of these...with saturated and unsaturated side chains were prepared, and their physical and structural properties were investigated. The reactivity of these new...stability, some previously reported amino-triazolium azides9 were screened for hypergolicity with N2O4 and IRFNA. The synthesis and structural and physical

  18. Liquid Azide Salts and Their Reactions with Common Oxidizers IRFNA and N2O4 (Preprint)

    DTIC Science & Technology

    2008-02-19

    chains were prepared and their physical and structural properties were investigated. The reactivity of these new as well as some previously reported...prepared and their physical and structural properties were investigated. The reactivity of these new as well as some previously reported ionic...for hypergolicity with N2O4 and IRFNA. The synthesis and structural and physical properties of some novel imidazolium azides with a variety of

  19. Nitrous oxide emission potentials of Burkholderia species isolated from the leaves of a boreal peat moss Sphagnum fuscum.

    PubMed

    Nie, Yanxia; Li, Li; Wang, Mengcen; Tahvanainen, Teemu; Hashidoko, Yasuyuki

    2015-01-01

    Using a culture-based nitrous oxide (N2O) emission assay, three active N2O emitters were isolated from Sphagnum fuscum leaves and all identified as members of Burkholderia. These isolates showed N2O emission in the medium supplemented with [Formula: see text] but not with [Formula: see text], and Burkholderia sp. SF-E2 showed the most efficient N2O emission (0.20 μg·vial(-1)·day(-1)) at 1.0 mM KNO3. In Burkholderia sp. SF-E2, the optimum pH for N2O production was 5.0, close to that of the phyllosphere of Sphagnum mosses, while the optimum temperature was uniquely over 30 °C. The stimulating effect of additional 1.5 mM sucrose on N2O emission was ignorable, but Burkholderia sp. SF-E2 upon exposure to 100 mg·L(-1) E-caffeic acid showed uniquely 67-fold higher N2O emission. All of the three N2O emitters were negative in both acetylene inhibition assay and PCR assay for nosZ-detection, suggesting that N2O reductase or the gene itself is missing in the N2O-emitting Burkholderia.

  20. Generation of purified nitric oxide from liquid N2O4 for the treatment of pulmonary hypertension in hypoxemic swine.

    PubMed

    Lovich, Mark A; Fine, David H; Denton, Ryan J; Wakim, Matt G; Wei, Abraham E; Maslov, Mikhail Y; Gamero, Lucas G; Vasquez, Gregory B; Johnson, Bryan J; Roscigno, Robert F; Gilbert, Richard J

    2014-02-15

    Inhaled nitric oxide (NO) selectively dilates pulmonary blood vessels, reduces pulmonary vascular resistance (PVR), and enhances ventilation-perfusion matching. However, existing modes of delivery for the treatment of chronic pulmonary hypertension are limited due to the bulk and heft of large tanks of compressed gas. We present a novel system for the generation of inhaled NO that is based on the initial heat-induced evaporation of liquid N2O4 into gas phase NO2 followed by the room temperature reduction to NO by an antioxidant, ascorbic acid cartridge just prior to inhalation. The biologic effects of NO generated from liquid N2O4 were compared with the effects of NO gas, on increased mean pulmonary artery pressure (mPAP) and PVR in a hypoxemic (FiO2 15%) swine model of pulmonary hypertension. We showed that NO concentration varied directly with the fixed cross sectional flow of the outflow aperture when studied at temperatures of 45, 47.5 and 50°C and was independent of the rate of heating. Liquid N2O4-sourced NO at 1, 5, and 20 ppm significantly reduced the elevated mPAP and PVR induced by experimental hypoxemia and was biologically indistinguishable from gas source NO in this model. These experiments show that it is feasible to generate highly purified NO gas from small volumes of liquid N2O4 at concentrations sufficient to lower mPAP and PVR in hypoxemic swine, and suggest that a miniaturized ambulatory system designed to generate biologically active NO from liquid N2O4 is achievable.

  1. Direct nitrous oxide emissions from rapeseed in Germany

    NASA Astrophysics Data System (ADS)

    Fuß, Roland; Andres, Monique; Hegewald, Hannes; Kesenheimer, Katharina; Köbke, Sarah; Räbiger, Thomas; Suarez, Teresa; Stichnothe, Heinz; Flessa, Heiner

    2014-05-01

    The production of first generation biofuels has increased over the last decade in Germany. However, there is a strong public and scientific debate concerning ecological impact and sustainability of biofuel production. The EU Renewables Directive requires biofuels to save 35 % of GHG emissions compared to fossil fuels. Starting in 2017, 50 % mitigation of GHG emissions must be achieved. This presents challenges for production of biofuels from rapeseed, which is one of the major renewable resources used for fuel production. Field emissions of nitrous oxide (N2O) and GHG emissions during production of fertilizers contribute strongest to the GHG balance of rapeseed biofuel. Thus, the most promising GHG mitigation option is the optimization of nitrogen fertilization. Since 2012, field trials are conducted on five German research farms to quantify direct GHG emissions. The sites were selected to represent the main rapeseed production regions in Germany as well as climatic regions and soil types. Randomized plot designs were established, which allow monitoring (using manual chambers) impact of fertilization intensity on direct emissions and yield of the typical crop sequence (winter rape - winter wheat - winter barley). The effect of substituting mineral fertilizer with biogas digestate with and without addition of a nitrification inhibitor is also studied. Here we present results from the first cropping season. In 2013, annual direct N2O emissions as well as yield normalized N2O emissions from rape were low. This can be explained with the weather conditions as 2013 was characterized by a cold and long winter with snow until mid spring. As a result, emissions were smaller than predicted by the IPCC emission factors or by the Global Nitrous Oxide Calculator (GNOC). However, emissions still depend on nitrogen input.

  2. UV-induced N2O emission from plants

    NASA Astrophysics Data System (ADS)

    Bruhn, Dan; Albert, Kristian R.; Mikkelsen, Teis N.; Ambus, Per

    2014-12-01

    Nitrous oxide (N2O) is an important long-lived greenhouse gas and precursor of stratospheric ozone-depleting mono-nitrogen oxides. The atmospheric concentration of N2O is persistently increasing; however, large uncertainties are associated with the distinct source strengths. Here we investigate for the first time N2O emission from terrestrial vegetation in response to natural solar ultra violet radiation. We conducted field site measurements to investigate N2O atmosphere exchange from grass vegetation exposed to solar irradiance with and without UV-screening. Further laboratory tests were conducted with a range of species to study the controls and possible loci of UV-induced N2O emission from plants. Plants released N2O in response to natural sunlight at rates of c. 20-50 nmol m-2h-1, mostly due to the UV component. The emission response to UV-A is of the same magnitude as that to UV-B. Therefore, UV-A is more important than UV-B given the natural UV-spectrum at Earth's surface. Plants also emitted N2O in darkness, although at reduced rates. The emission rate is temperature dependent with a rather high activation energy indicative for an abiotic process. The prevailing zone for the N2O formation appears to be at the very surface of leaves. However, only c. 26% of the UV-induced N2O appears to originate from plant-N. Further, the process is dependent on atmospheric oxygen concentration. Our work demonstrates that ecosystem emission of the important greenhouse gas, N2O, may be up to c. 30% higher than hitherto assumed.

  3. Seasonal nitrous oxide flux from an intensively managed pasture in a humid subtropical ecosystem

    NASA Technical Reports Server (NTRS)

    Brams, Eugene A.; Anthony, W. H.; Hutchinson, G. L.; Livingston, G. P.

    1989-01-01

    Nitrous oxide (N2O) flux from vented chambers was measured over intensively and minimally managed bermuda grass hay meadows in a humid, subtropical ecosystem for several years during scheduled sampling protocol following harvest, fertilization and rainfall events while measuring diel N2O emissions once during each of 5 seasonal day growth cycles which divided each calendar year. Soil pools of nitrite NO2(-), nitrate NO3(-), and ammonia (NH3) were measured in soil samples taken at 2 and 10 cm depths during each emission collection to determine transformations of the nitrogen pools coupled with N2O emissions. The highest diel N2O emission occur midday in the Spring cycle, measuring 9.0 g N/ha/d only for several weeks, while emissions dropped to less than 1.0 g N/ha/day during hot, dry, and colder months. Intensively managed meadows (4 fertilizations and harvests per year plus pest management) induced higher seasonal N2O emissions than minimal treatment (1 fertilization and harvest) averaging 2.75 and 5.97 g N/ha/day. Nitrous oxide emission data as responses to soil parameters and environmental parameters were also measured where air temperature, soil moisture, and fertilization were the most powerful factors.

  4. Copper control of bacterial nitrous oxide emission and its impact on vitamin B12-dependent metabolism.

    PubMed

    Sullivan, Matthew J; Gates, Andrew J; Appia-Ayme, Corinne; Rowley, Gary; Richardson, David J

    2013-12-03

    Global agricultural emissions of the greenhouse gas nitrous oxide (N2O) have increased by around 20% over the last 100 y, but regulation of these emissions and their impact on bacterial cellular metabolism are poorly understood. Denitrifying bacteria convert nitrate in soils to inert di-nitrogen gas (N2) via N2O and the biochemistry of this process has been studied extensively in Paracoccus denitrificans. Here we demonstrate that expression of the gene encoding the nitrous oxide reductase (NosZ), which converts N2O to N2, is regulated in response to the extracellular copper concentration. We show that elevated levels of N2O released as a consequence of decreased cellular NosZ activity lead to the bacterium switching from vitamin B12-dependent to vitamin B12-independent biosynthetic pathways, through the transcriptional modulation of genes controlled by vitamin B12 riboswitches. This inhibitory effect of N2O can be rescued by addition of exogenous vitamin B12.

  5. Biological sources and sinks of nitrous oxide and strategies to mitigate emissions

    PubMed Central

    Thomson, Andrew J.; Giannopoulos, Georgios; Pretty, Jules; Baggs, Elizabeth M.; Richardson, David J.

    2012-01-01

    Nitrous oxide (N2O) is a powerful atmospheric greenhouse gas and cause of ozone layer depletion. Global emissions continue to rise. More than two-thirds of these emissions arise from bacterial and fungal denitrification and nitrification processes in soils, largely as a result of the application of nitrogenous fertilizers. This article summarizes the outcomes of an interdisciplinary meeting, ‘Nitrous oxide (N2O) the forgotten greenhouse gas’, held at the Kavli Royal Society International Centre, from 23 to 24 May 2011. It provides an introduction and background to the nature of the problem, and summarizes the conclusions reached regarding the biological sources and sinks of N2O in oceans, soils and wastewaters, and discusses the genetic regulation and molecular details of the enzymes responsible. Techniques for providing global and local N2O budgets are discussed. The findings of the meeting are drawn together in a review of strategies for mitigating N2O emissions, under three headings, namely: (i) managing soil chemistry and microbiology, (ii) engineering crop plants to fix nitrogen, and (iii) sustainable agricultural intensification. PMID:22451101

  6. Isotopologue signatures of nitrous oxide produced by nitrate-ammonifying bacteria isolated from soil

    NASA Astrophysics Data System (ADS)

    Behrendt, Undine; Well, Reinhard; Giesemann, Anette; Ulrich, Andreas; Augustin, Jürgen

    2015-04-01

    21to36o [3] ,which are much closer to the values of N2O from the investigated DNRA bacteria. However, the N2O formed under denitrifying conditions by organisms investigated so far can be distinguished with respect to its source (DNRA or denitrification) but a broader database is needed which cover a larger spectrum of taxa. [1] Sutka et al. Distinguishing nitrous oxide production from nitrification and denitrification on the basis of isotopomer abundances. Appl. Env. Microbiol. 2006, 72, 638. [2] Toyoda et al. Fractionation of N2O isotopomers during production by denitrifier. Soil Biol. Biochem. 2005, 37, 1535. [3] Rohe et al. Dual isotope and isotopomer signatures of nitrous oxide from fungal denitrification - a pure culture study. Rapid Commun. Mass Spectrom. 2014, 28, 1893

  7. Nitrous oxide in the tropical Atlantic Ocean: first results from the german SOLAS cruise M55

    NASA Astrophysics Data System (ADS)

    Walter, S.; Bange, H.; Wallace, D.

    2003-04-01

    NITROUS OXIDE IN THE TROPICAL ATLANTIC: FIRST RESULTS FROM THE GERMAN SOLAS CRUISE M55 S. Walter, H.W. Bange, D.W.R. Wallace Marine Biogeochemistry Division, Institute for Marine Research, Düsternbrooker Weg 20, 24105 Kiel, Germany swalter@ifm.uni-kiel.de Nitrous oxide (N2O) is an atmospheric trace gas which received increased attention in recent years because of its relevance for the Earth's climate and stratospheric chemistry. N2O is formed during microbial processes such as nitrification and denitrification in considerable amounts in the subsurface layer of the ocean. Thus, oceanic emissions of N2O play a major role for its atmospheric budget. However, measurements of N2O in the tropical Atlantic are sparse. The spatial distribution of N2O in the tropical Atlantic Ocean was determined during the first German SOLAS (Surface Ocean - Lower Atmosphere Study) cruise Meteor 55 from Willemstad (Curacao, Netherlands Antilles) to Douala (Cameroon) from 12 October to 17 November 2002. At 21 selected stations about 1200 N2O concentrations measurements were performed with a GC/ECD headspace technique. The mean relative error of the measurements was about 2%. Four general features are visible from the N2O depth profiles: (i) N2O is supersaturated throughout the water column. (ii) There is a considerable accumulation of N2O below the euphotic zone with maximum values at 250-400m water depth associated with lower oxygen concentrations. (iii) An increasing trend in the maximum N2O concentrations from the western to the eastern Atlantic which is inversely correlated with dissolved oxygen values in the oxygen minimum zone. (iv) An increasing trend in the N2O concentrations from the western to the eastern Atlantic basin in depths below 2000m which seems to be correlated with the age of the water masses. The inverse correlation with oxygen suggests that N2O in the tropical Atlantic is formed mainly by nitrification. Our results will be discussed in view of global-change induced

  8. Effects of different forms of plant-derived organic matter on nitrous oxide emissions.

    PubMed

    Qiu, Qingyan; Wu, Lanfang; Ouyang, Zhu; Li, Binbin; Xu, Yanyan

    2016-07-13

    To investigate the impact of different forms of plant-derived organic matter on nitrous oxide (N2O) emissions, an incubation experiment with the same rate of total nitrogen (N) application was carried out at 25 °C for 250 days. Soils were incorporated with maize-derived organic matter (i.e., maize residue-derived dissolved organic matter and maize residues with different C/N ratios) and an inorganic N fertilizer (urea). The pattern and magnitude of nitrous oxide (N2O) emissions were affected by the form of N applied. Single application of maize-derived organic matter resulted in a higher N2O emission than single application of the inorganic N fertilizer or combined application of the inorganic N fertilizer and maize-derived organic matter. The positive effect of maize residue-derived dissolved organic matter (DOM) addition on N2O emissions was relatively short-lived and mainly occurred at the early stage following DOM addition. In contrast, the positive effect induced by maize residue addition was more pronounced and lasted for a longer period. Single application of maize residues resulted in a substantial decrease in soil nitric nitrogen (NO3(-)-N), but it did not affect the production of N2O. No significant relationship between N2O emission and NO3(-)-N and ammonium nitrogen (NH4(+)-N) suggested that the availability of soil N was not limiting the production of N2O in our study. The key factors affecting soil N2O emission were the soil dissolved organic carbon (DOC) content and metabolism quotient (qCO2). Both of them could explain 87% of the variation in cumulative N2O emission. The C/N ratio of maize-derived organic matter was a poor predictor of N2O emission when the soil was not limited by easily available C and the available N content met the microbial N demands for nitrification and denitrification. The results suggested that the magnitude of N2O emission was determined by the impact of organic amendments on soil C availability and microbial activity

  9. Simulation of N2O peak emissions on peat soils with SWAP-ANIMO

    NASA Astrophysics Data System (ADS)

    Stolk, P. C.; Hendriks, R. H. A.; Jacobs, C. M. J.; Weststrate, H.; Duyzer, J.

    2009-04-01

    Nitrous oxide (N2O) is a very strong greenhouse gas, with agricultural soils as its main anthropogenic source. Various management practices, like fertilization or tillage, can give rise to pulses of N2O emissions. In spite of their short duration, in the order of a couple of days to weeks, these pulses can constitute major part of total annual nitrous oxide emission. Understanding, predicting and ultimately mitigating these pulses poses a considerable challenge. N2O is mainly produced by nitrifiers and denitrifiers. These require different conditions with respect to aerobicity and available mineral N. Simulation models offer a promising tool to test and further develop process knowledge on N2O production and -emission. SWAP-ANIMO is a process oriented biogeochemical model, originally developed for the simulation of nitrate leaching, that has recently been extended with an N2O module. It includes production and consumption of N2O by denitrification, production of N2O by nitrification and transport by diffusion and convection in the soil water and soil air. Here we present the validation of N2O surface flux simulations, with daily measurements of fluxes from grassland on peat in The Netherlands. As a first step to evaluate the simulation of the processes in the soil, we compare observed and simulated soil N2O concentration profiles.

  10. Stimulation of nitrous oxide production resulted from soil fumigation with chloropicrin

    NASA Astrophysics Data System (ADS)

    Spokas, K.; Wang, D.

    Agricultural soils are a major source of the atmospheric greenhouse gas nitrous oxide (N 2O). Agronomic practices such as tillage and fertilizer applications can significantly affect the production and consumption of N 2O because of alteration in soil physical, chemical, and biochemical activities. Soil fumigation is an agronomic practice used to control soil-borne disease pathogens, weeds, plant-parasitic nematodes, and fungi. The strong impact of fumigants on soil microorganisms can indirectly affect the production and/or consumption of N 2O and would potentially alter net emissions from agricultural soils. Laboratory incubation and field soil fumigation studies were conducted to determine the potential impact of soil fumigation on the dynamics of N 2O production. Laboratory soil incubations showed an eight-fold increase in the production rate of N 2O as a consequence of chloropicrin (CP) fumigation. This stimulation effect was confirmed by a seven-fold increase in N 2O emission rates in field plots following CP fumigation. The mechanism of N 2O production appeared to be microbial related; however, additional work is needed to fully elucidate the pathways.

  11. Nitrogen transformations in intensive aquaculture system and its implication to climate change through nitrous oxide emission.

    PubMed

    Hu, Zhen; Lee, Jae Woo; Chandran, Kartik; Kim, Sungpyo; Sharma, Keshab; Brotto, Ariane Coelho; Khanal, Samir Kumar

    2013-02-01

    The rapid development of aquaculture could result in significant environmental concerns such as eutrophication and climate change. However, to date, very few studies have been conducted to investigate nitrogen transformations in aquaculture systems; and specifically the emission of nitrous oxide (N(2)O), which is an important greenhouse gas and ozone-depleting substance. In this study, nitrogen transformations in intensive laboratory-scale Chinese catfish (Clarias fuscus) aquaculture systems were investigated by identifying and quantifying N(2)O emissions. Results indicated that about 1.3% of the nitrogen input was emitted as N(2)O gas. Dissolved oxygen (DO) concentrations and feeding rates had significant effects on N(2)O emissions. Higher N(2)O emissions were obtained in aquaculture systems with lower DO concentrations and higher feeding rates. Both nitrification and denitrification appeared to be responsible for the emissions of N(2)O. Key factors which correlated with the N(2)O emission rate in aquaculture systems were NO(2)(-), DO and total ammonia nitrogen concentrations.

  12. The effects of plant diversity on nitrous oxide emissions in hydroponic microcosms

    NASA Astrophysics Data System (ADS)

    Sun, Hongying; Zhang, Chongbang; Song, Changchun; Chang, Scott X.; Gu, Baojing; Chen, Zhengxin; Peng, Changhui; Chang, Jie; Ge, Ying

    2013-10-01

    Previous studies have shown that plant diversity can improve the wastewater purification efficiency of constructed wetlands (CWs), but its effect on the nitrous oxide (N2O) emission in CWs has been unknown. To investigate the effect of plant diversity on the N2O emission, we established four plant species richness levels (each level containing 1, 2, 3 and 4 species, respectively) by using 96 hydroponic microcosms. Results showed that plant species richness enhanced the N2O emission, ranging from 27.1 to 115.4 μg N2O m-2 d-1, and improved nitrate removal (P < 0.001). The presence of Phalaris arundinacea within a given plant community increased the N2O emission (P < 0.001). The presence of Rumex japonicas had no influence on the N2O emissions (P > 0.05), but improved nitrogen removal (P < 0.001). Hence, our study highlights the importance of both plant species richness and species identity in mediating the N2O emission and nitrogen removal in CWs.

  13. Pinus sylvestris as a missing source of nitrous oxide and methane in boreal forest

    PubMed Central

    Machacova, Katerina; Bäck, Jaana; Vanhatalo, Anni; Halmeenmäki, Elisa; Kolari, Pasi; Mammarella, Ivan; Pumpanen, Jukka; Acosta, Manuel; Urban, Otmar; Pihlatie, Mari

    2016-01-01

    Boreal forests comprise 73% of the world’s coniferous forests. Based on forest floor measurements, they have been considered a significant natural sink of methane (CH4) and a natural source of nitrous oxide (N2O), both of which are important greenhouse gases. However, the role of trees, especially conifers, in ecosystem N2O and CH4 exchange is only poorly understood. We show for the first time that mature Scots pine (Pinus sylvestris L.) trees consistently emit N2O and CH4 from both stems and shoots. The shoot fluxes of N2O and CH4 exceeded the stem flux rates by 16 and 41 times, respectively. Moreover, higher stem N2O and CH4 fluxes were observed from wet than from dry areas of the forest. The N2O release from boreal pine forests may thus be underestimated and the uptake of CH4 may be overestimated when ecosystem flux calculations are based solely on forest floor measurements. The contribution of pine trees to the N2O and CH4 exchange of the boreal pine forest seems to increase considerably under high soil water content, thus highlighting the urgent need to include tree-emissions in greenhouse gas emission inventories. PMID:26997421

  14. Pinus sylvestris as a missing source of nitrous oxide and methane in boreal forest.

    PubMed

    Machacova, Katerina; Bäck, Jaana; Vanhatalo, Anni; Halmeenmäki, Elisa; Kolari, Pasi; Mammarella, Ivan; Pumpanen, Jukka; Acosta, Manuel; Urban, Otmar; Pihlatie, Mari

    2016-03-21

    Boreal forests comprise 73% of the world's coniferous forests. Based on forest floor measurements, they have been considered a significant natural sink of methane (CH4) and a natural source of nitrous oxide (N2O), both of which are important greenhouse gases. However, the role of trees, especially conifers, in ecosystem N2O and CH4 exchange is only poorly understood. We show for the first time that mature Scots pine (Pinus sylvestris L.) trees consistently emit N2O and CH4 from both stems and shoots. The shoot fluxes of N2O and CH4 exceeded the stem flux rates by 16 and 41 times, respectively. Moreover, higher stem N2O and CH4 fluxes were observed from wet than from dry areas of the forest. The N2O release from boreal pine forests may thus be underestimated and the uptake of CH4 may be overestimated when ecosystem flux calculations are based solely on forest floor measurements. The contribution of pine trees to the N2O and CH4 exchange of the boreal pine forest seems to increase considerably under high soil water content, thus highlighting the urgent need to include tree-emissions in greenhouse gas emission inventories.

  15. ATLAS instrument characterization - Accuracy of the AASE and AAOE nitrous oxide data sets

    NASA Technical Reports Server (NTRS)

    Loewenstein, M.; Podolske, J. R.; Strahan, S. E.

    1990-01-01

    The Airborne Tunabel Laser Absorption Spectrometer ATLAS was used to measure nitrous oxide in the 1987 Airborne Antarctic Ozone Experiment (AAOE) and in the 1989 Airborne Arctic Stratospheric Expedition (AASE). After the AASE, a detailed study of the ATLAS characteristics was undertaken to quantify the error inherent in the in situ measurement of atmospheric N2O. Using the latest calibration of the ATLAS (June 1989) and incorporating the recognized errors arising in the flight environment of ATLAS, it was established that, for both the AASE and the AAOE, most of the acquired N2O data sets are accurate to + or - 10 percent (2 sigma).

  16. Global methane and nitrous oxide emissions from terrestrial ecosystems due to multiple environmental changes

    DOE PAGES

    Tian, Hanqin; Chen, Guangsheng; Lu, Chaoqun; ...

    2015-03-16

    Greenhouse gas (GHG)-induced climate change is among the most pressing sustainability challenges facing humanity today, posing serious risks for ecosystem health. Methane (CH4) and nitrous oxide (N2O) are the two most important GHGs after carbon dioxide (CO2), but their regional and global budgets are not well known. In this paper, we applied a process-based coupled biogeochemical model to concurrently estimate the magnitude and spatial and temporal patterns of CH4 and N2O fluxes as driven by multiple environmental changes, including climate variability, rising atmospheric CO2, increasing nitrogen deposition, tropospheric ozone pollution, land use change, and nitrogen fertilizer use.

  17. Spatio-temporal variation in soil derived nitrous oxide emissions under sugarcane.

    PubMed

    Huang, Xiaodong; Grace, Peter; Mengersen, Kerrie; Weier, Keith

    2011-10-01

    Nitrous oxide (N(2)O) is a significant greenhouse gas with a global warming potential that is 300 times than that of carbon dioxide. Soil derived N(2)O emissions usually display a high degree of spatial and temporal variability because of their dependence on soil chemical and physical properties, and climate dependent environmental factors. However, there is little research that incorporates spatial dependence in the estimation of N(2)O emissions allowing for environmental factors in the same model. This study aims to examine the impact of two environmental factors (soil temperature and soil moisture) on N(2)O emissions and explore the spatial structure of N(2)O in the sub-tropical South East Queensland region of Australia. The replicated data on N(2)O emissions and soil properties were collected at a typical sugarcane land site covering 25 uniform grid points across 3600 m(2) between October 2007 and September 2008. A Bayesian conditional autoregressive (CAR) model was used to model spatial dependence. Results showed that soil moisture and soil temperature appeared to have substantially different effects on N(2)O emissions after taking spatial dependence into account in the four seasons. There was a substantial variation in the spatial distribution of N(2)O emission in the different seasons. The high N(2)O emission regions were accompanied by high uncertainty and changed in varying seasons in this study site. Spatial CAR models might be more plausible to elucidate and account for the uncertainty arising from unclear variables and spatial variability in the assessment of N(2)O emissions in soils, and more accurately identify relationships with key environmental factors and help to reduce the uncertainty of the soil parameters.

  18. Episodic nitrous oxide soil emissions in Brazilian savanna (cerrado) fire-scars. Final technical report

    SciTech Connect

    Nobre, A.D.; Crill, P.M.; Harriss, R.C.

    1994-08-01

    The seasonally burned cerrados of Brazil are the largest savanna-type ecosystem of South America and their contribution to the global atmospheric nitrous oxide (N2O) budget is unknown. Four types of fire-scarred cerrado along a vegetation gradient from grassland to forest were investigated during the wet season of 1992/93. The effect of fire and subsequent water additions on epiodic emissions of N2O and the associated profile dynamic of soil/gas phase N2O concentrations were studied for several months. Additionally, the effect on episodic emissions of N2O of nitrate and glucose additions to a cerrado soil after fire and the associated profile dynamic of soil/gas phase N2O mixing ratios were determined. Finally, N2O episodic emissions in cerrado converted to corn, soybean, and pasture fields were investigated during one growing/wet season. Results showed N2O consumption/emission for the four fire-scared savanna ecosystems, for nitrogen and carbon fertilization, and for agriculture/pasture ranging from -0.3 to +0.7, 1.8 to 9.1, and 0.5 to 3.7 g N2O-N ha(exp -1) d(exp -1), respectively. During the wet season the cerrado biome does not appear to be a major source of N2O to the troposphere, even following fire events. However, the results of this study suggest that conversion of the cerrado to high input agriculture, with liming and fertilization, can increase N2O emissions more than ten fold.

  19. Response of nitric and nitrous oxide fluxes to N fertilizer application in greenhouse vegetable cropping systems in southeast China.

    PubMed

    Zhang, Yaojun; Lin, Feng; Jin, Yaguo; Wang, Xiaofei; Liu, Shuwei; Zou, Jianwen

    2016-02-05

    It is of great concern worldwide that active nitrogenous gases in the global nitrogen cycle contribute to regional and global-scale environmental issues. Nitrous oxide (N2O) and nitric oxide (NO) are generally interrelated in soil nitrogen biogeochemical cycles, while few studies have simultaneously examined these two gases emission from typical croplands. Field experiments were conducted to measure N2O and NO fluxes in response to chemical N fertilizer application in annual greenhouse vegetable cropping systems in southeast China. Annual N2O and NO fluxes averaged 52.05 and 14.87 μg N m(-2) h(-1) for the controls without N fertilizer inputs, respectively. Both N2O and NO emissions linearly increased with N fertilizer application. The emission factors of N fertilizer for N2O and NO were estimated to be 1.43% and 1.15%, with an annual background emission of 5.07 kg N2O-N ha(-1) and 1.58 kg NO-N ha(-1), respectively. The NO-N/N2O-N ratio was significantly affected by cropping type and fertilizer application, and NO would exceed N2O emissions when soil moisture is below 54% WFPS. Overall, local conventional input rate of chemical N fertilizer could be partially reduced to attain high yield of vegetable and low N2O and NO emissions in greenhouse vegetable cropping systems in China.

  20. Response of nitric and nitrous oxide fluxes to N fertilizer application in greenhouse vegetable cropping systems in southeast China

    NASA Astrophysics Data System (ADS)

    Zhang, Yaojun; Lin, Feng; Jin, Yaguo; Wang, Xiaofei; Liu, Shuwei; Zou, Jianwen

    2016-02-01

    It is of great concern worldwide that active nitrogenous gases in the global nitrogen cycle contribute to regional and global-scale environmental issues. Nitrous oxide (N2O) and nitric oxide (NO) are generally interrelated in soil nitrogen biogeochemical cycles, while few studies have simultaneously examined these two gases emission from typical croplands. Field experiments were conducted to measure N2O and NO fluxes in response to chemical N fertilizer application in annual greenhouse vegetable cropping systems in southeast China. Annual N2O and NO fluxes averaged 52.05 and 14.87 μg N m‑2 h‑1 for the controls without N fertilizer inputs, respectively. Both N2O and NO emissions linearly increased with N fertilizer application. The emission factors of N fertilizer for N2O and NO were estimated to be 1.43% and 1.15%, with an annual background emission of 5.07 kg N2O-N ha‑1 and 1.58 kg NO-N ha‑1, respectively. The NO-N/N2O-N ratio was significantly affected by cropping type and fertilizer application, and NO would exceed N2O emissions when soil moisture is below 54% WFPS. Overall, local conventional input rate of chemical N fertilizer could be partially reduced to attain high yield of vegetable and low N2O and NO emissions in greenhouse vegetable cropping systems in China.

  1. High-performance amorphous gallium indium zinc oxide thin-film transistors through N2O plasma passivation

    NASA Astrophysics Data System (ADS)

    Park, Jaechul; Kim, Sangwook; Kim, Changjung; Kim, Sunil; Song, Ihun; Yin, Huaxiang; Kim, Kyoung-Kok; Lee, Sunghoon; Hong, Kiha; Lee, Jaecheol; Jung, Jaekwan; Lee, Eunha; Kwon, Kee-Won; Park, Youngsoo

    2008-08-01

    Amorphous-gallium-indium-zinc-oxide (a-GIZO) thin filmtransistors (TFTs) are fabricated without annealing, using processes and equipment for conventional a-Si :H TFTs. It has been very difficult to obtain sound TFT characteristics, because the a-GIZO active layer becomes conductive after dry etching the Mo source/drain electrode and depositing the a-SiO2 passivation layer. To prevent such damages, N2O plasma is applied to the back surface of the a-GIZO channel layer before a-SiO2 deposition. N2O plasma-treated a-GIZO TFTs exhibit excellent electrical properties: a field effect mobility of 37cm2/Vs, a threshold voltage of 0.1V, a subthreshold swing of 0.25V/decade, and an Ion/off ratio of 7.

  2. Interannual variation in nitrous oxide emissions from perennial ryegrass/white clover grassland used for dairy production.

    PubMed

    Burchill, William; Li, Dejun; Lanigan, Gary J; Williams, Micheal; Humphreys, James

    2014-10-01

    Nitrous oxide (N2 O) emissions are subject to intra- and interannual variation due to changes in weather and management. This creates significant uncertainties when quantifying estimates of annual N2 O emissions from grazed grasslands. Despite these uncertainties, the majority of studies are short-term in nature (<1 year) and as a consequence, there is a lack of data on interannual variation in N2 O emissions. The objectives of this study were to (i) quantify annual N2 O emissions and (ii) assess the causes of interannual variation in emissions from grazed perennial ryegrass/white clover grassland. Nitrous oxide emissions were measured from fertilized and grazed perennial ryegrass/white clover grassland (WC) and from perennial ryegrass plots that were not grazed and did not receive N input (GB), over 4 years from 2008 to 2012 in Ireland (52°51'N, 08°21'W). The annual N2 O-N emissions (kg ha(-1); mean ± SE) ranged from 4.4 ± 0.2 to 34.4 ± 5.5 from WC and from 1.7 ± 0.8 to 6.3 ± 1.2 from GB. Interannual variation in N2 O emissions was attributed to differences in annual rainfall, monthly (December) soil temperatures and variation in N input. Such substantial interannual variation in N2 O emissions highlights the need for long-term studies of emissions from managed pastoral systems.

  3. Role of Diffusion in Attributing the Source of Nitrous Oxide Production in the Upper Meter of an Agricultural Soil

    NASA Astrophysics Data System (ADS)

    Shcherbak, I.; Robertson, G. P.

    2012-12-01

    Agriculture is a major anthropogenic source of the potent GHG nitrous oxide (N2O). Distribution of subsurface sources of N2O in agricultural soils is not well understood. We examined N2O production at different soil depths to 1 meter in order to quantify by depth the total flux produced and the factors responsible for production. We measured subsurface N2O concentrations and surface N2O flux in three experiments: 1) duplicated tilled and no-tillage plots planted to corn, 2) rainfed and irrigated plots planted to corn at six N fertilizer levels, and 3) different replicated treatments of KBS LTER site - corn/soybean/wheat under conventional tillage, no-tillage, reduced input, and organic management, poplar trees, alfalfa, and early- and mid-successional communities. We measured diffusivity by injecting an inert tracer (SF6) and high concentrations of nitrous oxide to different depths to validate a diffusivity model. We developed a production function from experiments studying the effects of tillage, fertilization, and irrigation and applied it to treatments of KBS LTER. We attributed specific portions of N2O produced at different soil depths, with lower fluxes produced at depth despite surprisingly high N2O concentrations to 1m. Major seasonal fluxes were produced in the top 25 cm.

  4. Production and consumption of nitrous oxide in nitrate-ammonifying Wolinella succinogenes cells.

    PubMed

    Luckmann, Monique; Mania, Daniel; Kern, Melanie; Bakken, Lars R; Frostegård, Asa; Simon, Jörg

    2014-08-01

    Global warming is moving more and more into the public consciousness. Besides the commonly mentioned carbon dioxide and methane, nitrous oxide (N2O) is a powerful greenhouse gas in addition to its contribution to depletion of stratospheric ozone. The increasing concern about N2O emission has focused interest on underlying microbial energy-converting processes and organisms harbouring N2O reductase (NosZ), such as denitrifiers and ammonifiers of nitrate and nitrite. Here, the epsilonproteobacterial model organism Wolinella succinogenes is investigated with regard to its capacity to produce and consume N2O during growth by anaerobic nitrate ammonification. This organism synthesizes an unconventional cytochrome c nitrous oxide reductase (cNosZ), which is encoded by the first gene of an atypical nos gene cluster. However, W. succinogenes lacks a nitric oxide (NO)-producing nitrite reductase of the NirS- or NirK-type as well as an NO reductase of the Nor-type. Using a robotized incubation system, the wild-type strain and suitable mutants of W. succinogenes that either produced or lacked cNosZ were analysed as to their production of NO, N2O and N2 in both nitrate-sufficient and nitrate-limited growth medium using formate as electron donor. It was found that cells growing in nitrate-sufficient medium produced small amounts of N2O, which derived from nitrite and, most likely, from the presence of NO. Furthermore, cells employing cNosZ were able to reduce N2O to N2. This reaction, which was fully inhibited by acetylene, was also observed after adding N2O to the culture headspace. The results indicate that W. succinogenes cells are competent in N2O and N2 production despite being correctly grouped as respiratory nitrate ammonifiers. N2O production is assumed to result from NO detoxification and nitrosative stress defence, while N2O serves as a terminal electron acceptor in anaerobic respiration. The ecological implications of these findings are discussed.

  5. Model analysis of the spatial distribution and temporal trends of nitrous oxide sources and sinks. Cooperative thesis

    SciTech Connect

    Nevison, C.

    1994-01-01

    Nitrous oxide (N2O), an atmospheric trace gas that contributes to both greenhouse warming and stratosphere ozone depletion, is increasing at an annual rate of about 0.25%/yr. By use of a global model of the changing terrestrial nitrogen cycle, the timing and magnitude of this increase are shown to be consistent with enchanced microbial N2O production due to fertilizer, land clearing, livestock manure, and human sewage. Fertilizer appears to be a particularly important source. Increasing emissions from additional anthropogenic N2O sources, including fossil fuel combustion and nylon production are also shown to coincide with and contribute to N2O's annual atmospheric increase. Collectively, these industrial, combustion-related, and enhanced microbial N2O emissions add up to a total anthropogenic source of about 5 Tg N/yr.

  6. 21 CFR 868.1700 - Nitrous oxide gas analyzer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nitrous oxide gas analyzer. 868.1700 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1700 Nitrous oxide gas analyzer. (a) Identification. A nitrous oxide gas analyzer is a device intended to measure the concentration of nitrous...

  7. 21 CFR 868.1700 - Nitrous oxide gas analyzer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nitrous oxide gas analyzer. 868.1700 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1700 Nitrous oxide gas analyzer. (a) Identification. A nitrous oxide gas analyzer is a device intended to measure the concentration of nitrous...

  8. 21 CFR 868.1700 - Nitrous oxide gas analyzer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Nitrous oxide gas analyzer. 868.1700 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1700 Nitrous oxide gas analyzer. (a) Identification. A nitrous oxide gas analyzer is a device intended to measure the concentration of nitrous...

  9. 21 CFR 868.1700 - Nitrous oxide gas analyzer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Nitrous oxide gas analyzer. 868.1700 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1700 Nitrous oxide gas analyzer. (a) Identification. A nitrous oxide gas analyzer is a device intended to measure the concentration of nitrous...

  10. 21 CFR 868.1700 - Nitrous oxide gas analyzer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Nitrous oxide gas analyzer. 868.1700 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1700 Nitrous oxide gas analyzer. (a) Identification. A nitrous oxide gas analyzer is a device intended to measure the concentration of nitrous...

  11. Characteristic of nitrous oxide production in partial denitrification process with high nitrite accumulation.

    PubMed

    Du, Rui; Peng, Yongzhen; Cao, Shenbin; Wang, Shuying; Niu, Meng

    2016-03-01

    Nitrous oxide (N2O) production during the partial denitrification process with nitrate (NO3(-)-N) to nitrite (NO2(-)-N) transformation ratio of 80% was investigated in this study. Results showed that N2O was seldom observed before complete depletion of NO3(-)-N, but it was closely related to the reduction of NO2(-)-N rather than NO3(-)-N. High COD/NO3(-)-N was in favor of N2O production in partial denitrification with high NO2(-)-N accumulation. It was seriously enhanced at constant acidic pH due to the free nitrous acid (FNA) inhibition. However, the N2O production was much lower at initial pH of 5.5 and 6.5 due to the pH increase during denitrification process. Significantly, the pH turning point could be chosen as a controlled parameter to denote the end of NO3(-)-N reduction, which could not only achieve high NO2(-)-N accumulation but also decrease the N2O production significantly for practical application.

  12. Nitrous oxide production pathways in a partial nitritation-anammox reactor: Isotopic evidence for nitrous oxide production associated anaerobic ammonium oxidation?

    NASA Astrophysics Data System (ADS)

    Wunderlin, P.; Harris, E. J.; Joss, A.; Emmenegger, L.; Kipf, M.; Mohn, J.; Siegrist, H.

    2014-12-01

    Nitrous oxide (N2O) is a strong greenhouse gas and a major sink for stratospheric ozone. In biological wastewater treatment N2O can be produced via several pathways. This study investigates the dynamics of N2O emissions from a nitritation-anammox reactor, and links its interpretation to the nitrogen and oxygen isotopic signature of the emitted N2O. A 400-litre single-stage nitritation-anammox reactor was operated and continuously fed with digester liquid. The isotopic composition of N2O emissions was monitored online with quantum cascade laser absorption spectroscopy (QCLAS; Aerodyne Research, Inc.; Waechter et al., 2008). Dissolved ammonium and nitrate were monitored online (ISEmax, Endress + Hauser), while nitrite was measured with test strips (Nitrite-test 0-24mgN/l, Merck). Table 1. Summary of experiments conducted to understand N2O emissions Experimental conditions O2[mgO2/L] NO2-[mgN/L] NH4+[mgN/L] N2O/NH4+[%] Normal operation <0.1 <0.5 10 0.6 Normal operation, high NH4+ <0.1 <0.5 100 6.1 High aeration 0.5 to 1.5 up to 50 10 and 50 4.9 NO2- addition (oxic) <0.1 <0.5 to 4 10 5.8 NO2- addition (anoxic) 0 <0.5 to 4 10 3.2 NH2OH addition <0.1 <0.5 10 2.5 Results showed that under normal operating conditions, the N2O isotopic site preference (SP = d15Nα - d15Nβ) was much higher than expected - up to 41‰ - strongly suggesting an unknown N2O production pathway, which is hypothesized to be mediated by anammox activity (Figure 1). A less likely explanation is that the SP of N2O was increased by partial N2O reduction by heterotrophic denitrification. Various experiments were conducted to further investigate N2O formation pathways in the reactor. Our data reveal that N2O emissions increased when reactor operation was not ideal, for example when dissolved oxygen was too high (Table 1). SP measurements confirmed that these N2O peaks were due to enhanced nitrifier denitrification, generally related to nitrite build-up in the reactor (Figure 1; Table 1). Overall

  13. Nitrous Oxide Fluxes, Soil Oxygen, and Dentrification Potential from Urine and Non-urine Treated Soil Under Different Irrigation Frequencies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Despite increased use of irrigation to improve forage quality and quantity for grazing cattle (Bos taurus), few studies have assessed how irrigation practices influence nitrous oxide (N2O) emissions from urine-impacted soils. In particular, irrigation effects on soil oxygen (O2) availability, one of...

  14. Denitrification alternates between a source and sink of nitrous oxide in the hypolimnion of a thermally stratified reservoir

    EPA Science Inventory

    Nitrogen loading from developed watersheds to aquatic ecosystems can stimulate microbial denitrification, a process which reduces nitrate (NO3-) to dinitrogen (N2) or nitrous oxide (N2O), the latter a potent greenhouse gas. While aquatic ecosystems are a globally significant sou...

  15. Landscape control of nitrous oxide emissions during the transition from conservation reserve program to perennial grasses for bioenergy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Future liquid fuel demand from renewable sources may, in part, be met by converting the seasonally wet portions of the landscape currently managed for soil and water conservation to perennial energy crops. However, this shift may increase nitrous oxide (N2O) emissions, thus limiting the carbon benef...

  16. Process-based modeling of ammonia and nitrous oxide emissions from open lot beef and dairy facilities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Air emissions, such as ammonia (NH3) and nitrous oxide (N2O), vary considerably among beef and dairy open lot operations as influenced by the climate and manure pack conditions. Because of the challenges with direct measurement, process-based modeling is a recommended approach for estimating air emi...

  17. DEVELOPMENT OF SAMPLING AND ANALYTICAL METHODS FOR THE MEASUREMENT OF NITROUS OXIDE FROM FOSSIL FUEL COMBUSTION SOURCES

    EPA Science Inventory

    The report documents the technical approach and results achieved while developing a grab sampling method and an automated, on-line gas chromatography method suitable to characterize nitrous oxide (N2O) emissions from fossil fuel combustion sources. The two methods developed have...

  18. Nitrous oxide and methane fluxes from cattle excrement on C3 pasture and C4-dominated shortgrass steppe

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grazers play a major role in nutrient cycling of grassland ecosystems through biomass removal and excrement deposition (urine and feces). We studied the effects of cattle excrement patches (cattle urine at 430 and feces at 940 kg N ha-1) on nitrous oxide (N2O) and methane (CH4) fluxes using semi-st...

  19. CARBON DIOXIDE AND NITROUS OXIDE FLUXES IN ORGANIC, NO-TILL, AND CHISEL-TILL CROPPING SYSTEMS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Organic cropping systems may have the potential to increase soil C sequestration and reduce soil nitrous oxide (N2O) fluxes compared to conventional systems but organic systems are not well studied. We are measuring greenhouse gas fluxes and soil C sequestration in no-till, chisel-till and organic ...

  20. Methane and nitrous oxide emissions from a subtropical estuary (the Brisbane River estuary, Australia).

    PubMed

    Musenze, Ronald S; Werner, Ursula; Grinham, Alistair; Udy, James; Yuan, Zhiguo

    2014-02-15

    Methane (CH4) and nitrous oxide (N2O) are two key greenhouse gases. Their global atmospheric budgeting is, however, flout with challenges partly due to lack of adequate field studies determining the source strengths. Knowledge and data limitations exist for subtropical and tropical regions especially in the southern latitudes. Surface water methane and nitrous oxide concentrations were measured in a subtropical estuarine system in the southern latitudes in an extensive field study from 2010 to 2012 and water-air fluxes estimated using models considering the effects of both wind and flow induced turbulence. The estuary was found to be a strong net source of both CH4 and N2O all-year-round. Dissolved N2O concentrations ranged between 9.1 ± 0.4 to 45.3 ± 1.3 nM or 135 to 435% of atmospheric saturation level, while CH4 concentrations varied between 31.1 ± 3.7 to 578.4 ± 58.8 nM or 1210 to 26,430% of atmospheric saturation level. These results compare well with measurements from tropical estuarine systems. There was strong spatial variability with both CH4 and N2O concentrations increasing upstream the estuary. Strong temporal variability was also observed but there were no clear seasonal patterns. The degree of N2O saturation significantly increased with NOx concentrations (r(2)=0.55). The estimated water-air fluxes varied between 0.1 and 3.4 mg N2O m(-2)d(-1) and 0.3 to 27.9 mg CH4 m(-2)d(-1). Total emissions (CO2-e) were N2O (64%) dominated, highlighting the need for reduced nitrogen inputs into the estuary. Choice of the model(s) for estimation of the gas transfer velocity had a big bearing on the estimated total emissions.

  1. Nitrous oxide production and consumption by denitrification in a grassland: Effects of grazing and hydrology.

    PubMed

    Hu, Jing; Inglett, Kanika S; Clark, Mark W; Inglett, Patrick W; Ramesh Reddy, K

    2015-11-01

    Denitrification is generally recognized as a major mechanism contributing to nitrous oxide (N2O) production, and is the only known biological process for N2O consumption. Understanding factors controlling N2O production and consumption during denitrification will provide insights into N2O emission variability, and potentially predict capacity of soils to serve as sinks or sources of N2O. This study investigated the effects of hydrology and grazing on N2O production and consumption in a grassland based agricultural watershed. A batch incubation study was conducted on soils (0-10 cm) collected along a hydrological gradient representing isolated wetland (Center), transient zone (Edge) and pasture upland (Upland), from both grazed and ungrazed areas. Production and consumption potentials of N2O were quantified on soils under four treatments, including (i) ambient condition, and amended with (ii) NO3(-), (iii) glucose-C, and (iv) NO3(-) +glucose-C. The impacts of grazing on N2O production and consumption were not observed. Soils in hydrologically distinct zones responded differently to N2O production and consumption. Under ambient conditions, both production and consumption rates of Edge soils were higher than those observed for Center and Upland soils. Results of amended incubations suggested NO3(-) was a key factor limiting N2O production and consumption rates in all hydrological zones. Over 5-d incubation with NO3(-) amendment, cumulative production and consumption of N2O for Center soils were 1.6 and 3.3 times higher than Edge soils, and 3.6 and 7.6 times higher than Upland soils, respectively. However, cumulative N2O net production for Edge soils was the highest, with 2 to 3 times higher than Upland and Center soils. Our results suggest that the transient areas between wetland and upland are likely to be "hot spots" of N2O emissions in this ecosystem. Wetlands within agricultural landscapes can potentially function to reduce both NO3(-) leaching and N2O emissions.

  2. Sunlight stimulates methane uptake and nitrous oxide emission from the High Arctic tundra.

    PubMed

    Li, Fangfang; Zhu, Renbin; Bao, Tao; Wang, Qing; Xu, Hua

    2016-12-01

    Many environmental factors affecting methane (CH4) and nitrous oxide (N2O) fluxes have been investigated during the processes of carbon and nitrogen transformation in the boreal tundra. However, effects of sunlight on CH4 and N2O fluxes and their budgets were neglected in the boreal tundra. Here, summertime CH4 and N2O fluxes in the presence and total absence of sunlight were investigated at the six tundra sites (DM1-DM6) on Ny-Ålesund in the High Arctic. The mean CH4 fluxes at the tundra sites ranged from -4.7 to -158.6μg CH4 m(-2)h(-1) in the presence of light, indicating that a large CH4 sink occurred in the tundra soils. However, enhanced CH4 emission in total absence of light occurred at all the tundra sites. The mean N2O fluxes ranged from 7.4 to 14.6μg N2O m(-2)h(-1) in the presence of light, whereas in the absence of light all the tundra sites generally released less N2O, and even significant N2O uptake occurred there. Soil temperature, chamber temperature and soil moisture showed no significant correlations with tundra CH4 and N2O flux. The presence of sunlight increased tundra CH4 uptake by 114.2μg CH4 m(-2)h(-1) and N2O emission by 10.9μg N2O m(-2)h(-1) compared with total absence of light. Overall our results showed that tundra ecosystem switched from CH4 sink and N2O emission source in the presence of light to CH4 emission source and N2O sink in the absence of light. Therefore sunlight had an important effect on CH4 and N2O budgets in the High Arctic tundra. The exclusion of sunlight might overestimate CH4 budgets, but underestimate N2O budgets in the Arctic tundra ecosystem.

  3. Nitrous oxide emissions from a commercial cornfield (Zea mays) measured using the eddy-covariance technique

    NASA Astrophysics Data System (ADS)

    Huang, H.; Wang, J.; Hui, D.; Miller, D. R.; Bhattarai, S.; Dennis, S.; Smart, D.; Sammis, T.; Reddy, K. C.

    2014-08-01

    Increases in observed atmospheric concentrations of the long-lived greenhouse gas, nitrous oxide (N2O), have been well documented. However, information on event-related instantaneous emissions during fertilizer applications is lacking. With the development of fast-response N2O analyzers, the eddy covariance (EC) technique can be used to gather instantaneous measurements of N2O concentrations to quantify the exchange of nitrogen between the soil and atmosphere. The objectives of this study were to evaluate the performance of a new EC system, to measure the N2O flux with the system, and finally to examine relationships of the N2O flux with soil temperature, soil moisture, precipitation, and fertilization events. We assembled an EC system that included a sonic anemometer and a fast-response N2O analyzer (quantum cascade laser spectrometer) in a cornfield in Nolensville, Tennessee during the 2012 corn growing season (4 April-8 August). Fertilizer amounts totaling 217 kg N ha-1 were applied to the experimental site. The precision of the instrument was 0.066 ppbv for 10 Hz measurements. The seasonal mean detection limit of the N2O flux measurements was 2.10 ng N m-2 s-1. This EC system can be used to provide reliable N2O flux measurements. The cumulative emitted N2O for the entire growing season was 6.87 kg N2O-N ha-1. The 30 min average N2O emissions ranged from 0 to 11 100 μg N2O{-}N m-2 h-1 (mean = 257.5, standard deviation = 817.7). Average daytime emissions were much higher than night emissions (278.8 ± 865.8 vs. 100.0 ± 210.0 μg N2O-N m-2 h-1). Seasonal fluxes were highly dependent on soil moisture rather than soil temperature, although the diurnal flux was positively related to soil temperature. This study was one of the few experiments that continuously measured instantaneous, high-frequency N2O emissions in crop fields over a growing season of more than 100 days.

  4. Selective Encaging of N2O in N2O-N2 Binary Gas Hydrates via Hydrate-Based Gas Separation.

    PubMed

    Yang, Youjeong; Shin, Donghoon; Choi, Seunghyun; Woo, Yesol; Lee, Jong-Won; Kim, Dongseon; Shin, Hee-Young; Cha, Minjun; Yoon, Ji-Ho

    2017-02-22

    The crystal structure and guest inclusion behaviors of nitrous oxide-nitrogen (N2O-N2) binary gas hydrates formed from N2O/N2 gas mixtures are determined through spectroscopic analysis. Powder X-ray diffraction results indicate that the crystal structure of all the N2O-N2 binary gas hydrates is identified as the structure I (sI) hydrate. Raman spectra for N2O-N2 binary gas hydrate formed from N2O/N2 (80/20, 60/40, 40/60 mol %) gas mixtures reveal that N2O molecules occupy both large and small cages of the sI hydrate. In contrast, there is a single Raman band of N2O molecules for N2O-N2 binary gas hydrate formed from N2O/N2 (20/80 mol %) gas mixture, indicating that N2O molecules are trapped in only large cages of sI hydrate. From temperature-dependent Raman spectra and the Predictive Soave-Redlich-Kwong (PSRK) model calculation, we confirm the self-preservation of N2O-N2 binary gas hydrates in the temperature range of 210-270 K. Both the experimental measurements and the PSRK model calculations demonstrate the preferential occupation of N2O molecules rather than N2 molecules in the hydrate cages, leading to a possible process for separating N2O from gas mixtures via hydrate formation. The phase equilibrium conditions, pseudo pressure-composition (P-x) diagram, and gas storage capacity of N2O-N2 binary gas hydrates are discussed in detail.

  5. Minimizing nitrous oxide in biological nutrient removal from municipal wastewater by controlling copper ion concentrations.

    PubMed

    Zhu, Xiaoyu; Chen, Yinguang; Chen, Hong; Li, Xiang; Peng, Yongzhen; Wang, Shuying

    2013-02-01

    In this study, nitrous oxide (N(2)O) production during biological nutrient removal (BNR) from municipal wastewater was reported to be remarkably reduced by controlling copper ion (Cu(2+)) concentration. Firstly, it was observed that the addition of Cu(2+) (10-100 μg/L) reduced N(2)O generation by 54.5-73.2 % and improved total nitrogen removal when synthetic wastewater was treated in an anaerobic-aerobic (with low dissolved oxygen) BNR process. Then, the roles of Cu(2+) were investigated. The activities of nitrite and nitrous oxide reductases were increased by Cu(2+) addition, which accelerated the bio-reductions of both nitrite to nitric oxide (NO (2) (-)  → NO) and nitrous oxide to nitrogen gas (N(2)O → N(2)). The quantitative real-time polymerase chain reaction assay indicated that Cu(2+) addition increased the number of N(2)O reducing denitrifiers. Further investigation showed that more polyhydoxyalkanoates were utilized in the Cu(2+)-added system for denitrification. Finally, the feasibility of reducing N(2)O generation by controlling Cu(2+) was examined in two other BNR processes treating real municipal wastewater. As the Cu(2+) in municipal wastewater is usually below 10 μg/L, according to this study, the supplement of influent Cu(2+) to a concentration of 10-100 μg/L is beneficial to reduce N(2)O emission and improve nitrogen removal when sludge concentration in the BNR system is around 3,200 mg/L.

  6. [Research advances in control of N2O emission from municipal solid waste landfill sites].

    PubMed

    Cai, Chuan-Yu; Li, Bo; Lü, Hao-Hao; Wu, Wei-Xiang

    2012-05-01

    Landfill is one of the main approaches for municipal solid waste treatment, and landfill site is a main emission source of greenhouse gases nitrous oxide (N2O) and methane (CH4). As a high-efficient trace greenhouse gas, N2O has a very high warming potential, with a warming capacity 296 times of CO2, and has a long-term stability in atmosphere, giving greater damage to the ozone layer. Aiming at the researches in the control of N2O emission from municipal solid waste landfill sites, this paper summarized the characteristics and related affecting factors of the N2O emission from the landfill sites, and put forward a series of the measures adaptable to the N2O emission control of present municipal solid waste landfill sites in China. Some further research focuses on the control of N2O emission from the landfill sites were also presented.

  7. A sterilization system using ultraviolet photochemical reactions based on nitrous oxide and oxygen gases.

    PubMed

    Ohnishi, Yasutaka; Matsumoto, Hiroyuki; Iwamori, Satoru

    2016-03-01

    Active oxygen species (AOS) generated under ultraviolet (UV) lamps can be applied for various industrial processes owing to extremely strong oxidative abilities. We have already reported on an application of the AOS for a sterilization process of microorganisms. Here, a sterilization method using active oxygen generated under ultraviolet (UV) lamps introducing nitrous oxide (N2O) and oxygen gases into a vacuum chamber was investigated. Nitrogen dioxide (NO2) gas was readily produced from N2O by UV photochemical reactions under the low-pressure mercury lamp and then used to sterilize medical devices. We compared the ability of the N2O gas to sterilize Geobacillus stearothermophilus spores with those of conventional methods. Successful sterilization of spores on various biological indicators was achieved within 60 min, not only in sterilization bags but also in a lumen device.

  8. Interlaboratory calibration of atmospheric nitrous oxide measurements

    NASA Technical Reports Server (NTRS)

    Rasmussen, R. A.; Pierotti, D.

    1978-01-01

    Samples representative of Northern Hemispheric conditions in mid-1976 were analyzed by 11 laboratories to resolve the question of the absolute tropospheric concentration of nitrous oxide. The laboratories all employed electron capture-gas chromatography for the analysis. After exclusion of one anomalously low determination, the calibration results showed a mean concentration of 323.5 + or - 8.7 ppb v/v nitrous oxide.

  9. Summertime mid-to-upper tropospheric nitrous oxide over the Mediterranean as a footprint of Indian emissions

    NASA Astrophysics Data System (ADS)

    Kangah, Yannick; Ricaud, Philippe; Attié, Jean-Luc; Saitoh, Naoko; Hauglustaine, Didier; El Amraoui, Laaziz; Zbinden, Regina; Delon, Claire

    2016-04-01

    We used global scale thermal infrared measurements of mid-to-upper tropospheric nitrous oxide (N2O) from the Greenhouse gases Observing SATellite (GOSAT) and outputs from the 3D Chemical Transport Model LMDz-OR-INCA to assess the impact of the Indian subcontinent N2O emissions on the N2O field over the eastern Mediterranean Basin (MB) during summer. The use of nitrogen fertilizer coupled with high soil humidity during summer monsoon period produce high emissions of N2O in many south Asian countries and especially the Indian subcontinent. N2O is transported to the upper troposphere by updrafts associated to the monsoon and redistributed westward to the eastern Mediterranean via the Asian Monsoon Anticyclone. This summertime (June-July-August) enrichment in N2O in the eastern Mediterranean produces a maximum in the east-west difference of MB mid-to-upper tropospheric N2O anomaly representative for the period 2010-2013 with a maximum in July and a peak-to-peak amplitude of ~1.0 ± 0.3 ppbv observed by GOSAT consistently with LMDz-OR-INCA but less intense (~0.5 ppbv). This summertime enrichment of N2O over the eastern Mediterranean is consistent with the increase of the surface emissions and the convective precipitations over the Indian subcontinent during the summer monsoon period. N2O over the eastern Mediterranean can therefore be considered as a footprint of Indian summertime emissions.

  10. A post-Kyoto partner: Considering the stratospheric ozone regime as a tool to manage nitrous oxide

    PubMed Central

    Kanter, David; Mauzerall, Denise L.; Ravishankara, A. R.; Daniel, John S.; Portmann, Robert W.; Grabiel, Peter M.; Moomaw, William R.; Galloway, James N.

    2013-01-01

    Nitrous oxide (N2O) is the largest known remaining anthropogenic threat to the stratospheric ozone layer. However, it is currently only regulated under the 1997 Kyoto Protocol because of its simultaneous ability to warm the climate. The threat N2O poses to the stratospheric ozone layer, coupled with the uncertain future of the international climate regime, motivates our exploration of issues that could be relevant to the Parties to the ozone regime (the 1985 Vienna Convention and its 1987 Montreal Protocol) should they decide to take measures to manage N2O in the future. There are clear legal avenues to regulate N2O under the ozone regime as well as several ways to share authority with the existing and future international climate treaties. N2O mitigation strategies exist to address the most significant anthropogenic sources, including agriculture, where behavioral practices and new technologies could contribute significantly to reducing emissions. Existing policies managing N2O and other forms of reactive nitrogen could be harnessed and built on by the ozone regime to implement N2O controls. There are several challenges and potential cobenefits to N2O control which we discuss here: food security, equity, and implications of the nitrogen cascade. The possible inclusion of N2O in the ozone regime need not be viewed as a sign of failure of the United Nations Framework Convention on Climate Change to adequately deal with climate change. Rather, it could represent an additional valuable tool in sustainable development diplomacy. PMID:23440192

  11. A post-Kyoto partner: considering the stratospheric ozone regime as a tool to manage nitrous oxide.

    PubMed

    Kanter, David; Mauzerall, Denise L; Ravishankara, A R; Daniel, John S; Portmann, Robert W; Grabiel, Peter M; Moomaw, William R; Galloway, James N

    2013-03-19

    Nitrous oxide (N2O) is the largest known remaining anthropogenic threat to the stratospheric ozone layer. However, it is currently only regulated under the 1997 Kyoto Protocol because of its simultaneous ability to warm the climate. The threat N2O poses to the stratospheric ozone layer, coupled with the uncertain future of the international climate regime, motivates our exploration of issues that could be relevant to the Parties to the ozone regime (the 1985 Vienna Convention and its 1987 Montreal Protocol) should they decide to take measures to manage N2O in the future. There are clear legal avenues to regulate N2O under the ozone regime as well as several ways to share authority with the existing and future international climate treaties. N2O mitigation strategies exist to address the most significant anthropogenic sources, including agriculture, where behavioral practices and new technologies could contribute significantly to reducing emissions. Existing policies managing N2O and other forms of reactive nitrogen could be harnessed and built on by the ozone regime to implement N2O controls. There are several challenges and potential cobenefits to N2O control which we discuss here: food security, equity, and implications of the nitrogen cascade. The possible inclusion of N2O in the ozone regime need not be viewed as a sign of failure of the United Nations Framework Convention on Climate Change to adequately deal with climate change. Rather, it could represent an additional valuable tool in sustainable development diplomacy.

  12. Strategy and tactics of disarming GHG at the source: N2O reductase crops.

    PubMed

    Wan, Shen; Ward, Tonya Lynn; Altosaar, Illimar

    2012-08-01

    Nitrous oxide (N(2)O), the third most abundant greenhouse gas (GHG), is highly stable and plays a significant role in stratospheric ozone destruction. The primary anthropogenic source of N(2)O stems from use of nitrogen fertilizers in soil. The bacterial enzyme nitrous oxide reductase (N(2)OR), naturally found in some soils, is the only known enzyme capable of catalyzing the final step of the denitrification pathway, conversion of N(2)O to N(2). In this opinion, we discuss potential biology-based strategies to reduce N(2)O by amplifying the amount of available enzyme catalyst in agri-system environments during crop growth and in post-harvest detritus. N(2)OR from Pseudomonas stutzeri has been tested in transgenic plants with promising results. Such seed-borne phytoremediation systems targeted towards GHGs merit field testing.

  13. Measurement and Modeling of Site-specific Nitrogen and Oxygen Isotopic Composition of Atmospheric Nitrous Oxide at Mace Head, Ireland

    NASA Astrophysics Data System (ADS)

    McClellan, M. J.; Saikawa, E.; Prinn, R. G.; Ono, S.

    2015-12-01

    Global mixing ratios of atmospheric nitrous oxide (N2O), a potent greenhouse gas, have increased nearly linearly from the beginning of the modern industrial period to today, with the current global average in excess of 325 ppb. This increase can be largely attributed to anthropogenic activity above the level of N2O emissions from natural biotic sources. The effect of N2O on Earth's climate is twofold: in the troposphere, N2O is radiatively active and chemically inert, while it serves as a reactive source of ozone-destroying nitrogen oxides in the stratosphere. The marked altitudinal divide in its reactivity means that all stages in the N2O life cycle—emission, transport, and destruction—must be examined to understand the overall effect of N2O on Earth's climate. However, the understanding of the total impact of N2O is incomplete, as there remain significant uncertainties in the global budget of this gas. Due to unique isotopic substitutions (15N and 18O) made by different N2O sources and stratospheric chemical reactions, the measurement of N2O isotopic ratios in ambient air can help identify the distribution and magnitude of distinct source types. We present the first year of site-specific nitrogen and oxygen isotopic composition data from the MIT Stheno-tunable infrared direct absorption spectroscopy (TILDAS) instrument at Mace Head, Ireland. Aided by the Stheno preconcentration system, Stheno-TILDAS can achieve measurement precisions of 0.10‰ or greater for all isotopic ratios (δ15N and δ18O) in ambient N2O. We further compare these data to the results from Model for Ozone and Related Tracers version 4 (MOZART-4) simulations, including N2O isotopic fractionation processes and MERRA/GEOS-5 reanalysis meteorological fields. These results will form the basis of future Bayesian inverse modeling simulations that will constrain global N2O source, circulation, and sink dynamics better.

  14. Narcotic effects produced by nitrous oxide and hyperbaric nitrogen narcosis in rats performing a fixed-ratio test.

    PubMed

    Turle-Lorenzo, N; Zouani, B; Risso, J J

    1999-09-01

    Narcosis is a neurological syndrome that reduces capacities of divers. Although this phenomenon appeared at the end of 19th century, the mechanisms are not yet elucidated. The greatest technical problem is that these studies are carried out under hyperbaric conditions. Nitrous oxide is known to be an inducer of narcosis, at atmospheric pressure. The aim of this study is to compare two narcotic environments; a normobaric narcosis under several percentages of nitrous oxide, and an hyperbaric narcosis under 0.9 MPa of Nitrox (N2O2 mixture). This comparison is realized on rats submitted to a fixed-ratio 15 test, in which they have to press a lever to get rewarded. The results show significant performances decreases: the number of pressed lever are reduced by 50% under Nitrox and by 70% under N2O. Nitrous oxide could be considered as a normobaric model of hyperbaric narcosis.

  15. Evaluating uncertainties in nitrous oxide emission inventories with multi-scale observations for an agriculture-dominated region

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Lee, X.; Griffis, T. J.; Baker, J. M.

    2014-12-01

    Although agriculture accounts for about 80% of the global anthropogenic nitrous oxide (N2O) emissions, large uncertainties exist in regional inventories of N2O emissions from agriculture. The uncertainties mainly include poorly quantified plant flux, large heterogeneity of direct N2O emissions from cropland, and underestimated N2O lost through leaching and run off. To evaluate these uncertainties we conducted observations on three contrasting scales in the Midwest U.S., an agriculture dominated region (Zhang et al., 2014a). Observations at the plant, ecosystem, and regional scales include: 1) N2O flux measurements from the aboveground section of corn and soybean plants using newly designed plant chamber; 2) N2O flux-gradient measurements in a soybean-corn rotation field; and 3) N2O concentration measurements at 3 m and 200 m level on a communication tower (KCMP tower, 44°41'19''N, 93°4'22''W) that were used to estimate regional N2O fluxes with boundary layer methods (Zhang et al., 2014b). With these observations we evaluated the uncertainties in two frequently-used N2O inventories: EDGAR42 (Emission Database for Global Atmospheric Research, release version 4.2); and a national GHG inventory (U.S. EPA, 2014). The results indicate that EDGAR42 and EPA inventory underestimated N2O emissions for the region around the KCMP tower at least by a factor of three and two respectively. The underestimation is not likely caused by neglecting N2O flux from crops since N2O fluxes from unfertilized soybean and fertilized corn plants were about one magnitude lower than N2O emissions from the soil-plant ecosystem. The direct N2O emissions from cropland accounted for less than 20% of the regional flux, suggesting a significant influence by other sources and indirect emissions in the regional N2O budget. ReferencesU.S. EPA (2014) Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2012, 529 pp., Washington, D.C.. X Zhang, X Lee, TJ Griffis, AE Andrews, JM Baker, MD Erickson

  16. Soil fluxes of methane, nitrous oxide, and nitric oxide from aggrading forests in coastal Oregon

    USGS Publications Warehouse

    Erickson, Heather E.; Perakis, Steven S.

    2014-01-01

    Soil exchanges of greenhouse and other gases are poorly known for Pacific Northwest forests where gradients in nutrient availability and soil moisture may contribute to large variations in fluxes. Here we report fluxes of methane (CH4), nitrous oxide (N2O), and nitric oxide (NO) over multiple seasons from three naturally N-rich, aggrading forests of coastal Oregon, USA. Mean methane uptake rates (3.2 mg CH4 m−2 d−1) were high compared with forests globally, negatively related to water-filled pore space (WFPS), but unrelated to N availability or temperature. Emissions of NO (6.0 μg NO–N m−2 h−1) exceeded N2O (1.4 μg N2O–N m−2 h−1), except when WFPS surpassed 55%. Spatial variation in NO fluxes correlated positively with soil nitrate concentrations (which generally exceeded ammonium concentrations, indicating the overall high N status for the sites) and negatively with soil pH, and at one site increased with basal area of N2-fixing red alder. Combined NO and N2O emissions were greatest from the site with highest annual net N mineralization and lowest needle litterfall C/N. Our findings of high CH4 uptake and NO/N2O ratios generally >1 most likely reflect the high porosity of the andic soils underlying the widespread regenerating forests in this seasonally wet region.

  17. Modeling hyporheic flow paths to quantify nitrous oxide production in stream sediments

    NASA Astrophysics Data System (ADS)

    Quick, A. M.; Farrell, T. B.; Reeder, W. J.; Feris, K. P.; Tonina, D.; Benner, S. G.

    2013-12-01

    Nitrous oxide, a powerful greenhouse gas, is potentially produced in large volumes in the hyporheic zone during both the nitrification and denitrification phases of the nitrogen cycle. The conditions leading to N2O generation are poorly constrained due to difficulty in quantifying dissolved gases (O2, N2O) and chemical species (NH3 and NO3-) along flow paths in the hyporheic zone. We modeled N2O generation in the hyporheic zone using large (1 m length x 10 cm diameter) sediment columns, repeatedly measuring gas and chemical species before, during, and after steady state conditions. Column experiments were conducted with soil carbon percentages ranging from 0.01-0.5% (by dry mass). A linear relationship was observed between soil carbon percentages and oxygen consumption rates. With carbon percentages greater than 0.15%, dissolved oxygen concentrations were depleted to below 1 ppm in 2-4 hours travel time. The drop in dissolved oxygen below 1 ppm corresponded to a marked increase in N2O production within the sediments. The highest and most prolonged N2O production rates were observed in the column with intermediate (0.15%) carbon. After reaching their peak (up to 11 ppb N2O/hour for 0.15% carbon), N2O production rates declined, presumably due to conversion to N2 gas along the denitrification pathway. The amount of N2O generated in our 1D flow paths is directly proportional to the amount of carbon in the sediments and travel time along the flow path in the hyporheic zone (a function of flow rate and hydraulic properties of the sediments). Continuing studies examine the role of microbial populations and increased nitrate inputs on the production rates of N2O from the hyporheic zones of streams.

  18. Stable isotopic indicators of nitrous oxide and methane sources in Los Angeles, California

    NASA Astrophysics Data System (ADS)

    Townsend-Small, A.; Pataki, D.; Tyler, S.; Trumbore, S.

    2008-12-01

    As urbanization increasingly encroaches upon agricultural landscapes, there are greater potential sources of greenhouse gases and other atmospheric contaminants. Measurements of the isotopic composition of trace gases have the potential to distinguish between pollutant sources and quantify the proportional contribution of agricultural activities to the total atmospheric pool. In this study, we are measuring the isotopic composition of greenhouse gases N2O and CH4 emitted from cropland, animal feeding operations, and urban activities in the South Coast Air Basin in southern California. The ultimate goal of our project is to utilize atmospheric measurements of the isotopic composition of N2O and CH4 combined with studies of source signatures to determine the proportional contributions of cropland, animal operations, and urban sources of greenhouse gases to the atmosphere. Measurements of the δ13C of methane show excellent separation between urban sources, such as vehicle emissions, power plants, oil refineries, landfills, and sewage treatment plants and agricultural sources like cows, biogas, and cattle feedlots. For nitrous oxide, soil N2O sources showed good separation from wastewater treatment facilities using δ15N and δ18O. Within soil N2O sources, the isotopic composition of N2O from cropland soils was similar to N2O emissions from urban turfgrass. These data indicate that nitrification may be as important a source of N2O as denitrification in urban soils. We are also measuring N2O fluxes from soils and from sewage treatment processes, and preliminary data indicate that urban N2O fluxes are higher than initially assumed by managers and regulatory agencies.

  19. Interaction between nitrification, denitrification and nitrous oxide production in fumigated soils

    NASA Astrophysics Data System (ADS)

    Yan, Dongdong; Wang, Qiuxia; Mao, Liangang; Ma, Taotao; Li, Yuan; Ouyang, Canbin; Guo, Meixia; Cao, Aocheng

    2015-02-01

    Soil fumigation can increase mineral nitrogen due to the mineralization of soil microbial biomass killed during the fumigation, and as a result nitrous oxide (N2O) emission would increase. In addition, a fumigant's impact on soil nitrification and denitrification would also alter the dynamics of N2O production in fumigated soils. Laboratory incubation studies were conducted to quantify the dynamic changes in N2O production following various fumigant treatments, and to determine the interaction between nitrification, denitrification and N2O production in fumigated soils. Results showed a substantial increase in NH4+-N and dissolved amino acids (DAA) during 7 days fumigation at 1WAF (week after fumigation). The application of fumigants caused significant inhibition of nitrification. However the results relating to potential denitrification were quite different. The rates of potential denitrification in chloropicrin (Pic) and dazomet (DZ) treatments at 1WAF were 3.5 and 5.6 times higher than the untreated control. Potential denitrification was greatly stimulated after Pic and DZ fumigation. The N2O production rates in Pic and DZ fumigated soil were significantly higher than the untreated control at 1WAF in the tested soil type. The cumulative N2O emissions in Pic and DZ fumigated soil were also significantly higher than the untreated control, but there were no significant differences among 1,3-dichloropropene (1,3-D), dimethyl disulfide (DMDS) and untreated control. A positive relationship between N2O production and potential denitrification (PDN) was observed (r = 0.951, P < 0.01). Pic and DZ are both nitrogenous compounds. The breakdown products of Pic and DZ would be available for microbial-aided denitrification reactions as nitrogen sources leading to N2O production, indicating that Pic and DZ degradation stimulated denitrification activity responsible for soil N2O production.

  20. Emission of nitrous oxide from rice-wheat systems of Indo-Gangetic plains of India.

    PubMed

    Pathak, H; Bhatia, Arti; Prasad, Shiv; Singh, Shalini; Kumar, S; Jain, M C; Kumar, U

    2002-07-01

    Nitrous oxide (N2O) accounts for 5% of the total enhanced greenhouse effect and responsible for the destruction of the stratospheric ozone. The rice-wheat cropping system occupying 26 million ha of productive land in Asia could be a major source of N2O as most of the fertilizer N in this region is consumed by this system. Emission of N2O as influenced by application of urea, urea plus farm yard manure (FYM), and urea plus dicyandiamide (DCD), a nitrification inhibitor, was studied in rice-wheat systems of Indo-Gangetic plains of India. Total emission of N2O-N from the rice-wheat systems varied between 654 g ha(-1) in unfertilized plots and 1,570 g ha(-1) in urea fertilized plots. Application of FYM and DCD reduced emission of N2O-N in rice. The magnitude of reduction was higher with DCD. In wheat also N2O-N emission was reduced by DCD. FYM applied in rice had no residual effect on N2O-N emission in wheat. In rice intermittent wetting and drying condition of soil resulted in higher N2O-N emission than that of saturated soil condition. Treatments with 5 irrigations gave higher emissions in wheat than those with 3 irrigations. In rice-wheat system, typical of a farmer's field in Indo-Gangetic plains, where 240 kg N is generally applied through urea, N2O-N emission is 1,570 g ha(-1) (0.38% of applied N) and application of FYM and DCD reduced it to 1,415 and 1,096 g ha(-1), respectively.

  1. Effect of biochar and liming on soil nitrous oxide emissions from a temperate maize cropping system

    NASA Astrophysics Data System (ADS)

    Hüppi, R.; Felber, R.; Neftel, A.; Six, J.; Leifeld, J.

    2015-12-01

    Biochar, a carbon-rich, porous pyrolysis product of organic residues may positively affect plant yield and can, owing to its inherent stability, promote soil carbon sequestration when amended to agricultural soils. Another possible effect of biochar is the reduction in emissions of nitrous oxide (N2O). A number of laboratory incubations have shown significantly reduced N2O emissions from soil when mixed with biochar. Emission measurements under field conditions however are more scarce and show weaker or no reductions, or even increases in N2O emissions. One of the hypothesised mechanisms for reduced N2O emissions from soil is owing to the increase in soil pH following the application of alkaline biochar. To test the effect of biochar on N2O emissions in a temperate maize cropping system, we set up a field trial with a 20t ha-1 biochar treatment, a limestone treatment adjusted to the same pH as the biochar treatment (pH 6.5), and a control treatment without any addition (pH 6.1). An automated static chamber system measured N2O emissions for each replicate plot (n = 3) every 3.6 h over the course of 8 months. The field was conventionally fertilised at a rate of 160 kg N ha-1 in three applications of 40, 80 and 40 kg N ha-1 as ammonium nitrate. Cumulative N2O emissions were 52 % smaller in the biochar compared to the control treatment. However, the effect of the treatments overall was not statistically significant (p = 0.27) because of the large variability in the data set. Limed soils emitted similar mean cumulative amounts of N2O as the control. There is no evidence that reduced N2O emissions with biochar relative to the control is solely caused by a higher soil pH.

  2. A post-Kyoto partner: Considering the Montreal Protocol as a tool to manage nitrous oxide

    NASA Astrophysics Data System (ADS)

    Mauzerall, D. L.; Kanter, D.; Ravishankara, A. R.; Daniel, J. S.; Portmann, R. W.; Grabiel, P.; Moomaw, W.; Galloway, J. N.

    2012-12-01

    While nitrous oxide (N2O) was recently identified as the largest remaining anthropogenic threat to the stratospheric ozone layer, it is currently regulated under the 1997 Kyoto Protocol due to its simultaneous ability to warm the climate. The threat N2O poses to the stratospheric ozone layer, coupled with the uncertain future of the international climate regime, motivates our exploration of issues that could be relevant to the Parties to the 1987 Montreal Protocol if they decide to take measures to manage N2O in the future. There are clear legal avenues for the Montreal Protocol and its parent treaty, the 1985 Vienna Convention, to regulate N2O, as well as several ways to share authority with the existing and future international climate treaties. N2O mitigation strategies exist to address its most significant anthropogenic sources, including agriculture, where behavioral practices and new technologies could contribute significantly to mitigation efforts. Existing policies managing N2O and other forms of reactive nitrogen could be harnessed and built upon by the Montreal Protocol's existing bodies to implement N2O controls. Given the tight coupling of the nitrogen cycle, such controls would likely simultaneously reduce emissions of reactive nitrogen and hence have co-benefits for ecosystems and public health. Nevertheless, there are at least three major regulatory challenges that are unique and central to N2O control: food security, equity, and the nitrogen cascade. The possible inclusion of N2O in the Montreal Protocol need not be viewed as a sign of the Kyoto Protocol's failure to adequately deal with climate change, given the complexity of the issue. Rather, it could represent an additional tool in the field of sustainable development diplomacy.lt;img border=0 src="images/B43K-06_B.jpg">

  3. Global observation of nitrous oxide: changes in growth rate and spatial patterns

    NASA Astrophysics Data System (ADS)

    Hall, B. D.; Dlugokencky, E. J.; Dutton, G. S.; Nance, J. D.; Crotwell, A. M.; Mondeel, D. J.; Elkins, J. W.

    2015-12-01

    Nitrous oxide (N2O) currently exerts the third largest climate forcing of the long-lived greenhouse gases, after CO2 and CH4. N2O is also involved in the destruction of stratospheric ozone. It is produced by microbial activity in soils and oceans, and also by industry. The atmospheric burden of N2O has increased more than 20% from its preindustrial level of ~270 nmol mol-1 (ppb). Much of this increase is related to the application of nitrogen-containing fertilizers, including manure. The NOAA Global Monitoring Division has measured the atmospheric mole fraction of N2O at Earth's surface in air samples collected around the globe (since the late 1970s) and at in situ sites mostly in the Western Hemisphere (since 1998). ). Measurements of the global burden and growth rate constrain global emissions, e.g. 18.2 ± 2.7 Tg N yr-1 in 2013, where most of the uncertainty is related to uncertainty in the global lifetime. The average growth rate of N2O from 1990 to 2010 was ~0.75 ppb yr-1. Since 2004, however, the growth rate has been increasing, and is now about 25% higher than the 1990-2010 average. Between 2010 and 2013 the growth rate averaged ~0.95 ppb yr-1. As the growth rate increased from 2004-2013, gradients derived from surface, zonal-mean N2O mole fraction, such the mean pole-to-pole difference, and the difference between NH temperate latitudes and the southern polar region, decreased. This suggests a change in the distribution of N2O emissions over this period. We will present our N2O data and examine trends, gradients, and other features that could shed light on recent changes in the growth rate. We will also compare N2O gradients to those of other trace gases, such as SF6.

  4. Episodic nitrous oxide soil emissions in Brazilian savanna (cerrado) fire-scars

    NASA Technical Reports Server (NTRS)

    Nobre, A. D.; Crill, P. M.; Harriss, R. C.

    1994-01-01

    The seasonally burned cerrados of Brazil are the largest savanna-type ecosystem of South America and their contribution to the global atmospheric nitrous oxide (N20) budget is unknown. Four types of fire-scarred cerrado along a vegetation gradient from grassland to forest were investigated during the wet season of 1992/93. The effect of fire and subsequent water additions on epiodic emissions of N2O and the associated profile dynamic of soil/gas phase N2O concentrations were studied for several months. Additionally, the effect on episodic emissions of N2O of nitrate and glucose additions to a cerrado soil after fire and the associated profile dynamic of soil/gas phase N2O mixing ratios were determined. Finally, N2O episodic emissions in cerrado converted to corn, soybean, and pasture fields were investigated during one growing/wet season. Results showed N2O consumption/emission for the four fire-scared savanna ecosystems, for nitrogen and carbon fertilization, and for agriculture/pasture ranging from -0.3 to +0.7, 1.8 to 9.1, and 0.5 to 3.7 g N2O-N ha(exp -1) d(exp -1), respectively. During the wet season the cerrado biome does not appear to be a major source of N2O to the troposphere, even following fire events. However, the results of this study suggest that conversion of the cerrado to high input agriculture, with liming and fertilization, can increase N2O emissions more than ten fold.

  5. Evaluating Soil Oxygen as a Control on N2O Emissions from Ruminant Urine Patches under Different Irrigation Frequencies

    NASA Astrophysics Data System (ADS)

    Owens, J.; Clough, T. J.; Laubach, J.; Hunt, J.; Venterea, R. T.; Phillips, R. L.

    2015-12-01

    Urine patches from grazing ruminant animals are a significant source of nitrous oxide (N2O) emissions, and irrigation is increasingly used to improve forage quality and yield for grazing cattle. The objective of this study was to test whether irrigation frequency influenced N2O emissions from urine patches on a free-draining grazed pasture soil. It was hypothesized that greater irrigation frequency would increase soil moisture thereby lowering soil oxygen (O2), and that these O2-limited conditions would increase the potential for N2O to be reduced to nitrogen gas (N2), resulting in lower N2O emissions. A field trial tested the effects of two irrigation frequencies and urine deposition on N2O fluxes measured daily for 35 days. Denitrification potential measurements using the acetylene inhibition technique were completed to infer N2O/(N2O+N2) ratios, and soil O2 concentrations were measured continuously at three depths within the soil profile. While a more frequent irrigation treatment resulted in a lower N2O/(N2O+N2) ratio, this did not give rise to lower N2O emissions. Nitrous oxide fluxes were not influenced by irrigation frequency, and approximately 0.09% of the nitrogen applied as urine was emitted as N2O from both irrigation treatments. Neither N2O nor soil O2 varied with individual irrigation events. Soil O2 ranged from 17 to 20% expect following urine deposition, where it temporarily decreased to 13%. Soil O2 measurements failed to explain N2O emissions, but a relationship was derived between N2O fluxes and estimates of soil gas diffusivity (Dp/Do). This work is the first to show how soil O2 concentrations vary under a urine patch and under different irrigation treatments, and supports Dp/Do as robust predictor of N2O emissions in situ.

  6. Nitrous oxide flux and nitrogen transformations across a landscape gradient in Amazonia

    NASA Technical Reports Server (NTRS)

    Livingston, Gerald P.; Vitousek, Peter M.; Matson, Pamela A.

    1988-01-01

    Nitrous oxide flux and nitrogen turnover were measured in three types of Amazonian forest ecosystems within Reserva Florestal Ducke near Manaus, Brazil. Nitrogen mineralization and nitrate production measured during 10-day laboratory incubations were 3-4 times higher in clay soils associated with 'terra firme' forests on ridge-top and slope positions than in 'campinarana' forests on bottomland sand soils. In contrast, nitrous oxide fluxes did not differ significantly among sites, but were highly variable in space and time. The observed frequency distribution of flux was positively skewed, with a mean overall sites and all sampling times of 1.3 ng N2O-N/sq cm per hr. Overall, the flux estimates were comparable to or greater than those of temperature forests, but less than others reported for Amazoonia. Results from a field fertilization experiment suggest that most nitrous oxide flux was associated with denitrification of soil nitrate.

  7. Oxygen atom kinetics in silane-hydrogen-nitrous oxide mixtures behind reflected shock waves

    NASA Astrophysics Data System (ADS)

    Javoy, S.; Mével, R.; Dupré, G.

    2010-11-01

    Resonance Absorption Spectroscopy has been used to study the O-atom dynamics behind reflected shock waves in highly argon diluted silane-hydrogen-nitrous oxide mixtures in the temperature range 1606-2528 K and at total pressures from 234 to 584 kPa. The absorptions at 130.5 nm of N 2O, SiH 4 and Si have been taken into account to compare simulated and experimental absorption profiles. A detailed kinetic model has been also used to interpret the results and reaction pathway and sensitivity analyses have been performed to underline important elementary reactions. A comparison with the O-atom kinetic in silane-nitrous oxide and hydrogen-nitrous oxide mixtures is also proposed.

  8. Disentangling the complexity of nitrous oxide cycling in coastal sediments: Results from a novel multi-isotope approach

    NASA Astrophysics Data System (ADS)

    Wankel, S. D.; Buchwald, C.; Charoenpong, C.; Ziebis, W.

    2014-12-01

    Although marine environments contribute approximately 30% of the global atmospheric nitrous oxide (N2O) flux, coastal systems appear to comprise a disproportionately large majority of the ocean-atmosphere flux. However, there exists a wide range of estimates and future projections of N2O production and emission are confounded by spatial and temporal variability of biological sources and sinks. As N2O is produced as an intermediate in both oxidative and reductive microbial processes and can also be consumed as an electron acceptor, a mechanistic understanding of the regulation of these pathways remains poorly understood. To improve our understanding of N2O dynamics in coastal sediments, we conducted a series of intact flow-through sediment core incubations (Sylt, Germany), while manipulating both the O2 and NO3- concentrations in the overlying water. Steady-state natural abundance isotope fluxes (δ15N and δ18O) of nitrate, nitrite, ammonium and nitrous oxide were monitored throughout the experiments. We also measured both the isotopomer composition (site preference (SP) of the 15N in N2O) as well as the Δ17O composition in experiments conducted with the addition of NO3- with an elevated Δ17O composition (19.5‰), which provide complementary information about the processes producing and consuming N2O. Results indicate positive N2O fluxes (to the water column) across all conditions and sediment types. Decreasing dissolved O2 to 30% saturation resulted in reduced N2O fluxes (5.9 ± 6.5 μmol m2 d-1) compared to controls (17.8 ± 6.5 μmol m-2 d-1), while the addition of 100 μM NO3- yielded higher N2O fluxes (49.0 ± 18.5 μmol m-2 d-1). In all NO3- addition experiments, the Δ17O signal from the NO3- was clearly observed in the N2O efflux implicating denitrification as a large source of N2O. However, Δ17O values were always lower (1.9 to 8.6‰) than the starting NO3- indicating an important role for nitrification-based N2O production and/or O isotope exchange

  9. Stable isotope natural abundance of nitrous oxide emitted from Antarctic tundra soils: effects of sea animal excrement depositions.

    PubMed

    Zhu, Renbin; Liu, Yashu; Li, Xianglan; Sun, Jianjun; Xu, Hua; Sun, Liguang

    2008-11-01

    Nitrous oxide (N2O), a greenhouse gas, is mainly emitted from soils during the nitrification and denitrification processes. N2O stable isotope investigations can help to characterize the N2O sources and N2O production mechanisms. N2O isotope measurements have been conducted for different types of global terrestrial ecosystems. However, no isotopic data of N2O emitted from Antarctic tundra ecosystems have been reported although the coastal ice-free tundra around Antarctic continent is the largest sea animal colony on the global scale. Here, we report for the first time stable isotope composition of N2O emitted from Antarctic sea animal colonies (including penguin, seal and skua colonies) and normal tundra soils using in situ field observations and laboratory incubations, and we have analyzed the effects of sea animal excrement depositions on stable isotope natural abundance of N2O. For all the field sites, the soil-emitted N2O was 15N- and 18O-depleted compared with N2O in local ambient air. The mean delta values of the soil-emitted N2O were delta15N = -13.5 +/- 3.2 per thousand and delta18O = 26.2 +/- 1.4 per thousand for the penguin colony, delta15N = -11.5 +/- 5.1 per thousand and delta18O = 26.4 +/- 3.5 per thousand for the skua colony and delta15N = -18.9 +/- 0.7 per thousand and delta18O = 28.8 +/- 1.3 per thousand for the seal colony. In the soil incubations, the isotopic composition of N2O was measured under N2 and under ambient air conditions. The soils incubated under the ambient air emitted very little N2O (2.93 microg N2O--N kg(-1)). Under N2 conditions, much more N2O was formed (9.74 microg N2O--N kg(-1)), and the mean delta15N and delta18O values of N2O were -19.1 +/- 8.0 per thousand and 21.3 +/- 4.3 per thousand, respectively, from penguin colony soils, and -17.0 +/- 4.2 per thousand and 20.6 +/- 3.5 per thousand, respectively, from seal colony soils. The data from in situ field observations and laboratory experiments point to denitrification as the

  10. Nitrogen fertiliser formulation: The impact on N2O emissions

    NASA Astrophysics Data System (ADS)

    Harty, Mary; Krol, Dominika; Carolan, Rachael; McNeill, Gavin; McGeough, Karen; Laughlin, Ronnie; Watson, Catherine; Richards, Karl; Lanigan, Gary; Forrestal, Patrick

    2015-04-01

    Agriculture was responsible for 31% of Ireland's Agricultural Greenhouse Gas (GHG) emissions in 2012, with 39% of these emissions arising from chemical/organic fertilizers in the form of nitrous oxide (N2O). Switching from calcium ammonium nitrate (CAN) to a urea based fertiliser limits the soil residence period of nitrate, the major substrate for denitrification loss in the N2O form. However, urea is susceptible to ammonia (NH3) volatilisation but this risk can be managed using urease inhibitors. The aim of this study was to evaluate the effect of switching from CAN to urea, urea with the urease inhibitor N- (n-butyl) thiophosphoric triamide (trade name Agrotain®) and/or the nitrification inhibitor dicyandiamide (DCD on direct and indirect N2O emissions. The experiment is a two year study (commenced March 2013) at six permanent pasture sites located on the island of Ireland, at Johnstown Castle Co. Wexford, Moorepark Co. Cork and Hillsborough Co. Down, covering a range of soil textures and drainage characteristics. The experiment simulated a grazing environment; annual fertiliser N was applied at different rates (0, 100, 200, 300, 400 or 500 kg N ha-1) in five equal splits, with grass harvested prior to fertilizer application. Direct N2O emissions were quantified regularly using static chambers over 1 year and indirect N2O from ammonia volatilisation was measured using wind tunnels and annual emission factors calculated. Switching from CAN to urea dramatically reduced direct N2O emissions, but had little effect on dry-matter yield. However, there was evidence of pollution swapping of direct for indirect N2O from NH3. In the first year, two urea based formulations successfully reduced both direct and indirect N2O emissions at all sites. Fertiliser formulation strategy has the potential to be a solution for reduction of direct and indirect N2O emissions.

  11. NOAA's Global Network of N2O Observations

    NASA Astrophysics Data System (ADS)

    Dlugokencky, E. J.; Crotwell, A. M.; Crotwell, M.; Masarie, K. A.; Lang, P. M.; Dutton, G. S.; Hall, B. D.

    2014-12-01

    Nitrous oxide has surpassed CFC-12 to become the third largest contributor to radiative forcing. When climate impacts for equal emitted masses of N2O and CO2 are integrated over 100 years, N2O impacts are about 300 times greater than those of CO2. Increasing the atmospheric burden of N2O also decreases the abundance of O3 in the stratosphere. With reductions in emissions of ODSs as a result of the Montreal Protocol, N2O now has the largest ODP-weighted emissions of all gases. Given its long lifetime of about 130 years, today's emissions will impact climate and stratospheric O3 for a long time. Because emission rates are very small and spread over enormous areas, the detailed N2O budget has large uncertainties. It also means measurement requirements on precision and accuracy are stringent, especially for the background atmosphere. The Carbon Cycle Group of NOAA ESRL's Global Monitoring Division began measuring N2O in discrete air samples collected as part of its global cooperative air sampling network in 1998. Data from about 60 air sampling sites provide important constraints on the large-scale budget of N2O and provide boundary conditions for continental and regional-scale studies. This presentation will briefly describe the procedures used to ensure the data are of sufficient quality to meet scientific demands, and describe remaining limitations. Although sampling is infrequent (weekly), the data are quite useful in N2O budget studies. Examples will be given of large scale constraints on N2O's budget, including the global burden, trends in the burden, global emissions, spatial distributions, vertical gradients, and seasonal patterns.

  12. Atmospheric emissions and trends of nitrous oxide deduced from 10 years of ALE-GAGE data

    NASA Technical Reports Server (NTRS)

    Prinn, R.; Cunnold, D.; Alyea, F.; Rasmussen, R.; Simmonds, P.

    1990-01-01

    Long-term measurements of nitrous oxide (N2O) obtained during the Atmospheric Lifetime Experiment (ALE) and the Global Atmospheric Gases Experiment (GAGE) for a period from 1978 to 1988 are presented and interpreted. It is observed that the average concentration in the Northern Hemisphere is 0.75 +/- 0.16 ppbv higher than in the Southern Hemisphere and that the global average linear trend in N2O lies in the range from 0.25 to 0.31 percent/year. The measured trends and latitudinal distributions are shown to be consistent with the hypothesis that stratospheric photodissociation is the major atmospheric sink for N2O, while the cause of the N2O trend is suggested to be a combination of a growing tropical source and a growing Northern mid-latitude source. A 10-year average global N2O emission rate of (20.5 +/- 2.4) x 10 to the 12th g N2O/year is deduced from the ALE/GAGE data.

  13. Characterization of nitrous oxide emission from a rice-duck farming system in South China.

    PubMed

    Zhang, Jia-En; Ouyang, Ying; Huang, Zhao-Xiang

    2008-02-01

    Agricultural activities are important contributors to the emissions of greenhouse gases. This study ascertained the dynamic emission of nitrous oxide (N(2)O) from a paddy field under a rice-duck farming system in South China. Two different cultivation and fertilizer treatments, namely, organic fertilizer + ducks (OF+D) and chemical fertilizer + ducks (CF+D) treatments, were employed in this study. Experimental data showed that diurnal variations of N(2)O emission were highly correlated with the activities of ducklings. The rates of N(2)O emission were normally increased in the early morning and late afternoon due to the frequent movement of ducklings at these time periods. Our study further revealed that the rates of N(2)O emission from the paddy field varied with the types of fertilizers used as well as with the stages of the rice growth. In general, the rates of N(2)O emission were higher for the CF+D treatment than for the OF+D treatment, whereas more N(2)O was emitted from the paddy field at the tillering stage than at the heading stage. The global warming potential with the use of the organic fertilizer was about 22% lower than with the use of the chemical fertilizer.

  14. Global soil nitrous oxide emissions in a dynamic carbon-nitrogen model

    NASA Astrophysics Data System (ADS)

    Huang, Y. Y.; Gerber, S.

    2015-02-01

    Nitrous oxide (N2O) is an important greenhouse gas that also contributes to the depletion of stratospheric ozone. With high temporal and spatial heterogeneity, a quantitative understanding of terrestrial N2O emission, its variabilities and reponses to climate change is challenging. We added a soil N2O emission module to the dynamic global land model LM3V-N, and tested its sensitivity to soil moisture regime and responses to elevated CO2 and temperature. The model was capable of reproducing the average of cross-site observed annual mean emissions, although differences remained across individual sites if stand-level measurements were representative of gridcell emissions. Modelled N2O fluxes were highly sensitive to water filled pore space (WFPS), with a global sensitivity of approximately 0.25 Tg N year-1 per 0.01 change in WFPS. We found that the global response of N2O emission to CO2 fertilization was largely determined by the response of tropical emissions, whereas the extratropical response was weaker and different, highlighting the need to expand field studies in tropical ecosystems. Warming generally enhanced N2O efflux, and the enhancement was greatly dampened when combined with elevated CO2, although CO2 alone had a small effect. Our analysis suggests caution when extrapolation from current field CO2 enrichment and warming studies to the global scale.

  15. Stratospheric ozone depletion due to nitrous oxide: influences of other gases.

    PubMed

    Portmann, R W; Daniel, J S; Ravishankara, A R

    2012-05-05

    The effects of anthropogenic emissions of nitrous oxide (N(2)O), carbon dioxide (CO(2)), methane (CH(4)) and the halocarbons on stratospheric ozone (O(3)) over the twentieth and twenty-first centuries are isolated using a chemical model of the stratosphere. The future evolution of ozone will depend on each of these gases, with N(2)O and CO(2) probably playing the dominant roles as halocarbons return towards pre-industrial levels. There are nonlinear interactions between these gases that preclude unambiguously separating their effect on ozone. For example, the CH(4) increase during the twentieth century reduced the ozone losses owing to halocarbon increases, and the N(2)O chemical destruction of O(3) is buffered by CO(2) thermal effects in the middle stratosphere (by approx. 20% for the IPCC A1B/WMO A1 scenario over the time period 1900-2100). Nonetheless, N(2)O is expected to continue to be the largest anthropogenic emission of an O(3)-destroying compound in the foreseeable future. Reductions in anthropogenic N(2)O emissions provide a larger opportunity for reduction in future O(3) depletion than any of the remaining uncontrolled halocarbon emissions. It is also shown that 1980 levels of O(3) were affected by halocarbons, N(2)O, CO(2) and CH(4), and thus may not be a good choice of a benchmark of O(3) recovery.

  16. Nitrous oxide emissions in cover crop-based corn production systems

    NASA Astrophysics Data System (ADS)

    Davis, Brian Wesley

    Nitrous oxide (N2O) is a potent greenhouse gas; the majority of N2O emissions are the result of agricultural management, particularly the application of N fertilizers to soils. The relationship of N2O emissions to varying sources of N (manures, mineral fertilizers, and cover crops) has not been well-evaluated. Here we discussed a novel methodology for estimating precipitation-induced pulses of N2O using flux measurements; results indicated that short-term intensive time-series sampling methods can adequately describe the magnitude of these pulses. We also evaluated the annual N2O emissions from corn-cover crop (Zea mays; cereal rye [Secale cereale], hairy vetch [Vicia villosa ], or biculture) production systems when fertilized with multiple rates of subsurface banded poultry litter, as compared with tillage incorporation or mineral fertilizer. N2O emissions increased exponentially with total N rate; tillage decreased emissions following cover crops with legume components, while the effect of mineral fertilizer was mixed across cover crops.

  17. High-Frequency Isotope Measurements in Nitrous Oxide by Using Mid-Ir Laser Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Dong, F.; Baer, D. S.

    2010-12-01

    The stable isotope composition of atmosphere trace gases provides information of their origin and fate that cannot be determined from their concentration measurements alone. Biological source and loss processes, like bacterial production of N2O, are typically accompanied by isotopic selectivity associated with the kinetics of bond formation and destruction. Of the three important biologically mediated greenhouse gases (CO2, CH4 and N2O), the understanding of N2O isotopic budget in air lags far behind the other two gases. One of the reasons of this is due to the low concentration of N2O in ambient air (~320 ppbv), which leads to inherent difficulties in collection, extraction and analysis. We report on the development of novel instrumentation for real-time measurements of nitrogen-isotope ratio (δ15N) and mixing ratio [N2O] of nitrous oxide over a very wide range of mixing ratios. This novel technology, which employs cavity enhanced absorption and a mid-infrared laser and does not require any cryogenic components, has been developed for in situ simultaneous measurements of the mixing ratios of three main isotopomers - 14N14N16O, 15N14N16O and 14N15N16O, which leads to the nitrogen-isotope ratio (δ15N) and the 15N position-dependent enrichment. A precision of better than 1 per mil may be achieved in ambient air (300 ppbv N2O) in less than 300 seconds measurement time.

  18. The importance of climate change and nitrogen use efficiency for future nitrous oxide emissions from agriculture

    NASA Astrophysics Data System (ADS)

    Kanter, David R.; Zhang, Xin; Mauzerall, Denise L.; Malyshev, Sergey; Shevliakova, Elena

    2016-09-01

    Nitrous oxide (N2O) is an important greenhouse gas and ozone depleting substance. Previous projections of agricultural N2O (the dominant anthropogenic source) show emissions changing in tandem, or at a faster rate than changes in nitrogen (N) consumption. However, recent studies suggest that the carbon dioxide (CO2) fertilization effect may increase plant N uptake, which could decrease soil N losses and dampen increases in N2O. To evaluate this hypothesis at a global scale, we use a process-based land model with a coupled carbon-nitrogen cycle to examine how changes in climatic factors, land-use, and N application rates could affect agricultural N2O emissions by 2050. Assuming little improvement in N use efficiency (NUE), the model projects a 24%-31% increase in global agricultural N2O emissions by 2040-2050 depending on the climate scenario—a relatively moderate increase compared to the projected increases in N inputs (42%-44%) and previously published emissions projections (38%-75%). This occurs largely because the CO2 fertilization effect enhances plant N uptake in several regions, which subsequently dampens N2O emissions. And yet, improvements in NUE could still deliver important environmental benefits by 2050: equivalent to 10 Pg CO2 equivalent and 0.6 Tg ozone depletion potential.

  19. A geostatistical approach to identify and mitigate agricultural nitrous oxide emission hotspots.

    PubMed

    Turner, P A; Griffis, T J; Mulla, D J; Baker, J M; Venterea, R T

    2016-12-01

    Anthropogenic emissions of nitrous oxide (N2O), a trace gas with severe environmental costs, are greatest from agricultural soils amended with nitrogen (N) fertilizer. However, accurate N2O emission estimates at fine spatial scales are made difficult by their high variability, which represents a critical challenge for the management of N2O emissions. Here, static chamber measurements (n=60) and soil samples (n=129) were collected at approximately weekly intervals (n=6) for 42-d immediately following the application of N in a southern Minnesota cornfield (15.6-ha), typical of the systems prevalent throughout the U.S. Corn Belt. These data were integrated into a geostatistical model that resolved N2O emissions at a high spatial resolution (1-m). Field-scale N2O emissions exhibited a high degree of spatial variability, and were partitioned into three classes of emission strength: hotspots, intermediate, and coldspots. Rates of emission from hotspots were 2-fold greater than non-hotspot locations. Consequently, 36% of the field-scale emissions could be attributed to hotspots, despite representing only 21% of the total field area. Variations in elevation caused hotspots to develop in predictable locations, which were prone to nutrient and moisture accumulation caused by terrain focusing. Because these features are relatively static, our data and analyses indicate that targeted management of hotspots could efficiently reduce field-scale emissions by as much 17%, a significant benefit considering the deleterious effects of atmospheric N2O.

  20. Winter Cover Crops and Nitrous Oxide Emissions in Early Spring

    NASA Astrophysics Data System (ADS)

    Morris, C. K.; Walter, M. T.; Reiss, E. R.

    2015-12-01

    Winter cover crops mixtures can be used to manage greenhouse gas (GHG) emissions during critical periods such as spring thaw. Legumes are added to cover crops mixtures to increase crop productivity, but it is unknown if this effect decreases N2O emissions. In this project we investigate the relationship between biodiversity, productivity and GHG fluxes in cover crops varieties typically grown for soil heath in agricultural systems. Surface GHG emissions were measured with closed chambers beginning during snowmelt events and continuing until crops were tilled into the soil in early summer. We found that nitrous oxide emissions were reduced in cover cropped plots during the early spring thaw period when compared to bare soil. GHG emission reductions in agriculture can be achieved with proper selection of winter hardy cover crops.

  1. Direct Nitrous Oxide Emissions From Tropical And Sub-Tropical Agricultural Systems - A Review And Modelling Of Emission Factors

    NASA Astrophysics Data System (ADS)

    Albanito, Fabrizio; Lebender, Ulrike; Cornulier, Thomas; Sapkota, Tek B.; Brentrup, Frank; Stirling, Clare; Hillier, Jon

    2017-03-01

    There has been much debate about the uncertainties associated with the estimation of direct and indirect agricultural nitrous oxide (N2O) emissions in developing countries and in particular from tropical regions. In this study, we report an up-to-date review of the information published in peer-review journals on direct N2O emissions from agricultural systems in tropical and sub-tropical regions. We statistically analyze net-N2O-N emissions to estimate tropic-specific annual N2O emission factors (N2O-EFs) using a Generalized Additive Mixed Model (GAMM) which allowed the effects of multiple covariates to be modelled as linear or smooth non-linear continuous functions. Overall the mean N2O-EF was 1.2% for the tropics and sub-tropics, thus within the uncertainty range of IPCC-EF. On a regional basis, mean N2O-EFs were 1.4% for Africa, 1.1%, for Asia, 0.9% for Australia and 1.3% for Central & South America. Our annual N2O-EFs, estimated for a range of fertiliser rates using the available data, do not support recent studies hypothesising non-linear increase N2O-EFs as a function of applied N. Our findings highlight that in reporting annual N2O emissions and estimating N2O-EFs, particular attention should be paid in modelling the effect of study length on response of N2O.

  2. Direct Nitrous Oxide Emissions From Tropical And Sub-Tropical Agricultural Systems - A Review And Modelling Of Emission Factors

    PubMed Central

    Albanito, Fabrizio; Lebender, Ulrike; Cornulier, Thomas; Sapkota, Tek B.; Brentrup, Frank; Stirling, Clare; Hillier, Jon

    2017-01-01

    There has been much debate about the uncertainties associated with the estimation of direct and indirect agricultural nitrous oxide (N2O) emissions in developing countries and in particular from tropical regions. In this study, we report an up-to-date review of the information published in peer-review journals on direct N2O emissions from agricultural systems in tropical and sub-tropical regions. We statistically analyze net-N2O-N emissions to estimate tropic-specific annual N2O emission factors (N2O-EFs) using a Generalized Additive Mixed Model (GAMM) which allowed the effects of multiple covariates to be modelled as linear or smooth non-linear continuous functions. Overall the mean N2O-EF was 1.2% for the tropics and sub-tropics, thus within the uncertainty range of IPCC-EF. On a regional basis, mean N2O-EFs were 1.4% for Africa, 1.1%, for Asia, 0.9% for Australia and 1.3% for Central & South America. Our annual N2O-EFs, estimated for a range of fertiliser rates using the available data, do not support recent studies hypothesising non-linear increase N2O-EFs as a function of applied N. Our findings highlight that in reporting annual N2O emissions and estimating N2O-EFs, particular attention should be paid in modelling the effect of study length on response of N2O. PMID:28281637

  3. Nitrous oxide emission from an agricultural field fertilized with liquid lagoonal swine effluent

    NASA Astrophysics Data System (ADS)

    Whalen, S. C.; Phillips, R. L.; Fischer, E. N.

    2000-06-01

    Contemporary agriculture is characterized by the intensive production of livestock in confined facilities and land application of stored waste as an organic fertilizer. Emission of nitrous oxide (N2O) from receiving soils is an important but poorly constrained term in the atmospheric N2O budget. In particular, there are few data for N2O emissions from spray fields associated with industrial scale swine production facilities that have rapidly expanded in the southeastern United States. In an intensive, 24-day investigation over three spray cycles, we followed the time course for changes in N2O emission and soil physicochemical variables in an agricultural field irrigated with liquid lagoonal swine effluent. The total N (535 mg L-1) of the liquid waste was almost entirely NH4+-N (>90%) and thus had a low mineralization potential. Soil profiles for nitrification and denitrification indicated that >90% of potential activity was localized in the surface 20 cm. Application of this liquid fertilizer to warm (19° to 28°C) soils in a form that is both readily volatilized and immediately utilizable by the endogenous N-cycling microbial community resulted in a sharp decline in soil NH4+-N and supported a rapid but short-lived (i.e., days) burst of nitrification, denitrification, and N2O emission. Nitrous oxide fluxes as high as 9200 μg N2O-N m-2 h-1 were observed shortly after fertilization, but emissions decreased to prefertilization levels within a few days. Poor correlations between N2O efflux and soil physicochemical variables (temperature, moisture, NO3--N, NH4+-N) and fertilizer loading rate point to the complexity of interacting factors affecting N2O production and emission. Total fertilizer N applied and N2O-N emitted were 29.7 g m-2 (297 kg N ha-1) and 395 mg m-2, respectively. The fractional loss of applied N to N2O (corrected for background emission) was 1.4%, in agreement with the mean of 1.25% reported for mineral fertilizers. The direct effects of fertilizer

  4. Relative rates of nitric oxide and nitrous oxide production by nitrifiers, denitrifiers, and nitrate respirers

    NASA Technical Reports Server (NTRS)

    Anderson, I. C.; Levine, J. S.

    1986-01-01

    An account is given of the atmospheric chemical and photochemical effects of biogenic nitric and nitrous oxide emissions. The magnitude of the biogenic emission of NO is noted to remain uncertain. Possible soil sources of NO and N2O encompass nitrification by autotropic and heterotropic nitrifiers, denitrification by nitrifiers and denitrifiers, nitrate respiration by fermenters, and chemodenitrification. Oxygen availability is the primary determinant of these organisms' relative rates of activity. The characteristics of this major influence are presently investigated in light of the effect of oxygen partial pressure on NO and N2O production by a wide variety of common soil-nitrifying, denitrifying, and nitrate-respiring bacteria under laboratory conditions. The results obtained indicate that aerobic soils are primary sources only when there is sufficient moisture to furnish anaerobic microsites for denitrification.

  5. Effects of different nitrogen fertilizers on emission of nitrous oxide from soil

    NASA Astrophysics Data System (ADS)

    Breitenbeck, G. A.; Blackmer, A. M.; Bremner, J. M.

    1980-01-01

    Field studies of emissions of nitrous oxide (N2O) from a fallow soil treated with different forms and amounts of fertilizer N showed that N2O emissions from plots treated with N in the form of ammonium sulfate or urea markedly exceeded those from plots treated with the same amount of N in the form of calcium nitrate. This supports evidence from laboratory research that most of the N2O evolved from soils treated with ammonium and ammonium-producing fertilizers is generated by nitrifying microorganisms during oxidation of ammonium to nitrate and not, as previously assumed, through reduction of fertilizer-derived nitrate by denitrifying microorganisms. Emissions of N2O from plots treated with fertilizer N as ammonium sulfate or urea increased with the amount of N applied. Emissions of N2O in 25 days were increased 329-524% by application of 125 kg N ha-1 as ammonium sulfate or urea and increased 1024-1319% by the application of 250 kg N ha-1 in these forms, but these applications did not markedly increase N2O emissions after 25 days, and the fertilizer-induced emissions of N2O-N observed in 96 days from plots treated with ammonium sulfate or urea represented only 0.11-0.18% of the fertilizer N applied. Emissions of N2O from plots treated with different amounts of N as calcium nitrate did not increase with the amount of N applied and were not appreciably greater than the emissions observed when no fertilizer N was added.

  6. Methane and nitrous oxide distributions across the North American Arctic Ocean during summer, 2015

    NASA Astrophysics Data System (ADS)

    Fenwick, Lindsay; Capelle, David; Damm, Ellen; Zimmermann, Sarah; Williams, William J.; Vagle, Svein; Tortell, Philippe D.

    2017-01-01

    We collected Arctic Ocean water column samples for methane (CH4) and nitrous oxide (N2O) analysis on three separate cruises in the summer and fall of 2015, covering a ˜10,000 km transect from the Bering Sea to Baffin Bay. This provided a three-dimensional view of CH4 and N2O distributions across contrasting hydrographic environments, from the oligotrophic waters of the deep Canada Basin and Baffin Bay, to the productive shelves of the Bering and Chukchi Seas. Percent saturation relative to atmospheric equilibrium ranged from 30 to 800% for CH4 and 75 to 145% for N2O, with the highest concentrations of both gases occurring in the northern Chukchi Sea. Nitrogen cycling in the shelf sediments of the Bering and Chukchi Seas likely constituted the major source of N2O to the water column, and the resulting high N2O concentrations were transported across the Arctic Ocean in eastward-flowing water masses. Methane concentrations were more spatially heterogeneous, reflecting a variety of localized inputs, including likely sources from sedimentary methanogenesis and sea ice processes. Unlike N2O, CH4 was rapidly consumed through microbial oxidation in the water column, as shown by the 13C enrichment of CH4 with decreasing concentrations. For both CH4 and N2O, sea-air fluxes were close to neutral, indicating that our sampling region was neither a major source nor sink of these gases. Our results provide insight into the factors controlling the distribution of CH4 and N2O in the North American Arctic Ocean, and an important baseline data set against which future changes can be assessed.

  7. Carbon Sequestration and Nitrous Oxide Emissions from Urban Turfgrass Ecosystems in Southern California

    NASA Astrophysics Data System (ADS)

    Ampleman, M. D.; Czimczik, C. I.; Townsend-Small, A.; Trumbore, S. E.

    2008-12-01

    Irrigated turfgrass ecosystems sequester carbon in soil organic matter, but they may also release nitrous oxide, due to fertilization associated with intensive management practices. Nitrous oxide is an important green house gas with a global warming potential (GWP) of 300 times that of carbon dioxide on a 100 yr time horizon. Although regular irrigation and fertilization of turfgrass create favorable conditions for both C storage and N2O release via nitrification and denitrification by soil microbes, emissions from these highly managed ecosystems are poorly constrained. We quantified N2O emissions and C storage rates for turf grass in four urban parks in the city of Irvine, CA. The turf grass systems we studied were managed by the City of Irvine. Parks were established between 1975 and 2006 on former range land with the same initial parent material; are exposed to the same climate; and form a time series (chronosequence) for investigating rates of C accumulation. We also investigated the effects of management (e.g. grass species, fertilization rate), soil moisture and temperature, and park age on N2O emission from these parks. We quantified N2O emissions using static soil chamber with four 7 min. sampling intervals, and analyzed the samples using an electron capture gas chromatograph. Soil carbon accumulation rates were determined from the slope of the organic C inventory (from 0-20 cm depth) plotted against park age. C storage rates for soils in "leisure" areas were close to 2 Mg C ha-1 yr-1, similar to rates associated with forest regrowth in northeastern US forests. However, as park age and C storage increased, N2O emissions increased as well, such that emissions from the older parks (~20 ngN m-2 s-1) were comparable to published temperate agricultural fluxes. Initial estimates suggest that the GWP associated with N2O emissions approximately offsets the effect of C storage in these ecosystems.

  8. Bispectral EEG index monitoring of high-dose nitrous oxide and low-dose sevoflurane sedation.

    PubMed Central

    Hall, David L.; Weaver, Joel; Ganzberg, Steven; Rashid, Robert; Wilson, Stephen

    2002-01-01

    This single-blind controlled clinical study characterized the effects of 30-70% nitrous oxide (N2O) and 0.2-0.8% sevoflurane conscious sedation on quantitative electroencephalographic (EEG) readings of 22 healthy dental students as measured by the bispectral index (BIS). The study verified the 2 previously published BIS/N2O investigations showing no correlation between N2O dosage up to 70% and BIS. Observer's Assessment of Alertness and Sedation scores (OAA/S), however, correlated well with increasing doses of N2O from approximately 35 to 70%. A near linear dose-response relationship was established between OAA/S and end tidal (ET) sevoflurane concentrations of 0.4-0.7%. Only at the highest level of end tidal sevoflurane recorded, 0.7%, was statistically significant BIS depression seen. Subjects evaluated the acceptability of the sedative effect of the 2 gases, showing a slight preference for N2O. Comparable partial anterograde amnesia and sedation (OAA/S) were produced by both agents in administered concentrations of 40-70% N2O and 0.6-0.8% sevoflurane. Female subjects exhibited better memory and significantly less amnesia than males. No statistically significant changes occurred in any of the monitored vital signs. EMG readings demonstrated a statistically significant difference from control values only at the highest, 0.7%, ET concentration of sevoflurane. BIS does not appear useful for evaluating the level of nitrous oxide sedation in the dental setting but may have some value in assessing depth of sedation at deeper levels of sevoflurane sedation. Images Figure 1 Figure 2 PMID:15384293

  9. Lowering N2O emissions from soils using eucalypt biochar: the importance of redox reactions

    NASA Astrophysics Data System (ADS)

    Quin, P.; Joseph, S.; Husson, O.; Donne, S.; Mitchell, D.; Munroe, P.; Phelan, D.; Cowie, A.; van Zwieten, L.

    2015-11-01

    Agricultural soils are the primary anthropogenic source of atmospheric nitrous oxide (N2O), contributing to global warming and depletion of stratospheric ozone. Biochar addition has shown potential to lower soil N2O emission, with the mechanisms remaining unclear. We incubated eucalypt biochar (550 °C) - 0, 1 and 5% (w/w) in Ferralsol at 3 water regimes (12, 39 and 54% WFPS) - in a soil column, following gamma irradiation. After N2O was injected at the base of the soil column, in the 0% biochar control 100% of expected injected N2O was released into headspace, declining to 67% in the 5% amendment. In a 100% biochar column at 6% WFPS, only 16% of the expected N2O was observed. X-ray photoelectron spectroscopy identified changes in surface functional groups suggesting interactions between N2O and the biochar surfaces. We have shown increases in -O-C = N /pyridine pyrrole/NH3, suggesting reactions between N2O and the carbon (C) matrix upon exposure to N2O. With increasing rates of biochar application, higher pH adjusted redox potentials were observed at the lower water contents. Evidence suggests that biochar has taken part in redox reactions reducing N2O to dinitrogen (N2), in addition to adsorption of N2O.

  10. Lowering N2O emissions from soils using eucalypt biochar: the importance of redox reactions

    PubMed Central

    Quin, P; Joseph, S; Husson, O; Donne, S; Mitchell, D; Munroe, P; Phelan, D; Cowie, A; Van Zwieten, L

    2015-01-01

    Agricultural soils are the primary anthropogenic source of atmospheric nitrous oxide (N2O), contributing to global warming and depletion of stratospheric ozone. Biochar addition has shown potential to lower soil N2O emission, with the mechanisms remaining unclear. We incubated eucalypt biochar (550 °C) – 0, 1 and 5% (w/w) in Ferralsol at 3 water regimes (12, 39 and 54% WFPS) – in a soil column, following gamma irradiation. After N2O was injected at the base of the soil column, in the 0% biochar control 100% of expected injected N2O was released into headspace, declining to 67% in the 5% amendment. In a 100% biochar column at 6% WFPS, only 16% of the expected N2O was observed. X-ray photoelectron spectroscopy identified changes in surface functional groups suggesting interactions between N2O and the biochar surfaces. We have shown increases in -O-C = N /pyridine pyrrole/NH3, suggesting reactions between N2O and the carbon (C) matrix upon exposure to N2O. With increasing rates of biochar application, higher pH adjusted redox potentials were observed at the lower water contents. Evidence suggests that biochar has taken part in redox reactions reducing N2O to dinitrogen (N2), in addition to adsorption of N2O. PMID:26615820

  11. Termite mounds as hot spots of nitrous oxide emissions in South-Sudanian savanna of Burkina Faso (West Africa)

    NASA Astrophysics Data System (ADS)

    Brümmer, Christian; Papen, Hans; Wassmann, Reiner; Brüggemann, Nicolas

    2009-05-01

    Despite a considerable knowledge of the significant role of termites in the global methane budget, very little is known about their contribution to the global nitrous oxide (N2O) budget. Release of N2O from termite (Cubitermes fungifaber) mounds was measured at a natural savanna site in the southwest of Burkina Faso from May to September 2006. Termite N2O emissions were around 20 μg N2O-N m-2 h-1 at the end of the dry season, and up to two orders of magnitude higher than N2O emissions from the surrounding termite-free soil after the onset of the rainy season. The average N2O emission rate from termite mounds during the observation period was 204 μg N2O-N m-2 h-1, and termite mounds contributed 3.0% to total N2O emissions from this savanna ecosystem. However, in other tropical terrestrial ecosystems with other termite species and/or higher termite density this share might be significantly higher.

  12. Isotopocule analysis of biologically produced nitrous oxide in various environments.

    PubMed

    Toyoda, Sakae; Yoshida, Naohiro; Koba, Keisuke

    2017-03-01

    Natural abundance ratios of isotopocules, molecules that have the same chemical constitution and configuration, but that only differ in isotope substitution, retain a record of a compound's origin and reactions. A method to measure isotopocule ratios of nitrous oxide (N2 O) has been established by using mass analysis of molecular ions and fragment ions. The method has been applied widely to environmental samples from the atmosphere, ocean, fresh water, soils, and laboratory-simulation experiments. Results show that isotopocule ratios, particularly the (15) N-site preference (difference between isotopocule ratios (14) N(15) N(16) O/(14) N(14) N(16) O and (15) N(14) N(16) O/(14) N(14) N(16) O), have a wide range that depends on their production and consumption processes. Observational and laboratory studies of N2 O related to biological processes are reviewed and discussed to elucidate complex material cycles of this trace gas, which causes global warming and stratospheric ozone depletion. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:135-160, 2017.

  13. Nitrous oxide production during nitrification from organic solid waste under temperature and oxygen conditions.

    PubMed

    Nag, Mitali; Shimaoka, Takayuki; Komiya, Teppei

    2016-11-01

    Landfill aeration can accelerate the biological degradation of organic waste and reduce methane production; however, it induces nitrous oxide (N2O), a potent greenhouse gas. Nitrification is one of the pathways of N2O generation as a by-product during aerobic condition. This study was initiated to demonstrate the features of N2O production rate from organic solid waste during nitrification under three different temperatures (20°C, 30°C, and 40°C) and three oxygen concentrations (5%, 10%, and 20%) with high moisture content and high substrates' concentration. The experiment was carried out by batch experiment using Erlenmeyer flasks incubated in a shaking water bath for 72 h. A duplicate experiment was carried out in parallel, with addition of 100 Pa of acetylene as a nitrification inhibitor, to investigate nitrifiers' contribution to N2O production. The production rate of N2O ranged between 0.40 × 10(-3) and 1.14 × 10(-3) mg N/g-DM/h under the experimental conditions of this study. The rate of N2O production at 40°C was higher than at 20°C and 30°C. Nitrification was found to be the dominant pathway of N2O production. It was evaluated that optimization of O2 content is one of the crucial parameters in N2O production that may help to minimize greenhouse gas emissions and N turnover during aeration.

  14. Nitrous oxide persistently alleviates pain hypersensitivity in neuropathic rats: A dose-dependent effect

    PubMed Central

    Ben Boujema, Meric; Laboureyras, Emilie; Pype, Jan; Bessière, Baptiste; Simonnet, Guy

    2015-01-01

    BACKGROUND: Despite numerous pharmacological approaches, there are no common analgesic drugs that produce meaningful relief for the majority of patients with neuropathic pain. Although nitrous oxide (N2O) is a weak analgesic that acts via opioid-dependent mechanisms, it is also an antagonist of the N-methyl-D-aspartate receptor (NMDAR). The NMDAR plays a critical role in the development of pain sensitization induced by nerve injury. OBJECTIVE: Using the chronic constriction injury of the sciatic nerve in male rats as a preclinical model of neuropathic pain, the first aim of the present study was to evaluate the lowest N2O concentration and the shortest time of N2O postinjury exposure that would produce persistent relief of neuropathic pain. The second aim was to compare the effects of N2O with gabapentin, a reference drug used in human neuropathic pain relief. METHODS: Changes in the nociceptive threshold were evaluated using the paw pressure vocalization test in rats. RESULTS: Among the various N2O concentrations tested, which ranged from 25% to 50%, only 50% N2O single exposure for 1 h 15 min induced a persistent (minimum of three weeks) and significant (60%) reduction in pain hypersensitivity. A single gabapentin dose (75 mg/kg to 300 mg/kg, intraperitoneally) induced an acute (1 h to 1 h 30 min) dose-dependent effect, but not a persistent effect such as that observed with N2O. CONCLUSIONS: These preclinical results suggest that N2O is advantageous for long-lasting neuropathic pain relief after sciatic nerve injury compared with other drugs used in humans such as gabapentinoids or NMDAR antagonists. The present preclinical study provides a rationale for developing comparative clinical studies. PMID:26371891

  15. Spatial and temporal variability of nitrous oxide emissions in a mixed farming landscape of Denmark

    NASA Astrophysics Data System (ADS)

    Schelde, K.; Cellier, P.; Bertolini, T.; Dalgaard, T.; Weidinger, T.; Theobald, M. R.; Olesen, J. E.

    2012-08-01

    Nitrous oxide (N2O) emissions from agricultural land are variable at the landscape scale due to variability in land use, management, soil type, and topography. A field experiment was carried out in a typical mixed farming landscape in Denmark, to investigate the main drivers of variations in N2O emissions, measured using static chambers. Measurements were made over a period of 20 months, and sampling was intensified during two weeks in spring 2009 when chambers were installed at ten locations or fields to cover different crops and topography and slurry was applied to three of the fields. N2O emissions during spring 2009 were relatively low, with maximum values below 20 ng N m-2 s-1. This applied to all land use types including winter grain crops, grasslands, meadows, and wetlands. Slurry application to wheat fields resulted in short-lived two-fold increases in emissions. The moderate N2O fluxes and their moderate response to slurry application were attributed to dry soil conditions due to the absence of rain during the four previous weeks. Cumulative annual emissions from two arable fields that were both fertilized with mineral fertilizer and manure were large (17 kg N2O-N ha-1 yr-1 and 5.5 kg N2O-N ha-1 yr-1) during the previous year when soil water conditions were favourable for N2O production during the first month following fertilizer application. Our findings confirm the importance of weather conditions as well as nitrogen management on N2O fluxes.

  16. Nitrous oxide emissions at the landscape scale: spatial and temporal variability

    NASA Astrophysics Data System (ADS)

    Schelde, K.; Cellier, P.; Bertolini, T.; Dalgaard, T.; Weidinger, T.; Theobald, M. R.; Olesen, J. E.

    2011-12-01

    Nitrous oxide (N2O) emissions from agricultural land are variable at the landscape scale due to variability in land use, management, soil type, and topography. A field experiment was carried out in a typical mixed farming landscape in Denmark, to investigate the main drivers of variations in N2O emissions, measured using static chambers. Measurements were done over a period of 20 months, and sampling was intensified during two weeks in spring 2009 when chambers were installed at ten locations or fields to cover different crops and topography and slurry was applied to three of the fields. N2O emissions during the spring 2009 period were relatively low, with maximum values below 20 ng N m-2 s-1. This applied to all land use types including winter grain crops, grassland, meadow, and wetland. Slurry application to wheat fields resulted in short-lived two-fold increases in emissions. The moderate N2O fluxes and their moderate response to slurry application were attributed to dry soil moisture conditions due to the absence of rain during the four previous weeks. Measured cumulated annual emissions from two arable fields that were both fertilized with mineral fertilizer and manure were large (17 kg N2O-N ha-1 yr-1 and 5.5 kg N2O-N ha-1 yr-1, respectively) during the previous year when soil water conditions were favourable for N2O production during the first month following fertilizer application, confirming the importance of the climatic regime on N2O fluxes.

  17. Powerful greenhouse gas nitrous oxide adsorption onto intrinsic and Pd doped Single walled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Yoosefian, Mehdi

    2017-01-01

    Density functional studies on the adsorption behavior of nitrous oxide (N2O) onto intrinsic carbon nanotube (CNT) and Pd-doped (5,5) single-walled carbon nanotube (Pd-CNT) have been reported. Introduction of Pd dopant facilitates in adsorption of N2O on the otherwise inert nanotube as observed from the adsorption energies and global reactivity descriptor values. Among three adsorption features of N2O onto CNT, the horizontal adsorption with Eads = -0.16 eV exhibits higher adsorption energy. On the other hand the Pd-CNT exhibit strong affinity toward gas molecule and would cause a huge increase in N2O adsorption energies. Chemical and electronic properties of CNT and Pd-CNT in the absence and presence of N2O were investigated. Adsorption of N2O gas molecule would affect the electronic conductance of Pd-CNT that can serve as a signal of gas sensors and the increased energy gaps demonstrate the formation of more stable systems. The atoms in molecules (AIM) theory and the natural bond orbital (NBO) calculations were performed to get more details about the nature and charge transfers in intermolecular interactions within adsorption process. As a final point, the density of states (DOSs) calculations was achieved to confirm previous results. According to our results, intrinsic CNT cannot act as a suitable adsorbent while Pd-CNT can be introduced as novel detectable complex for designing high sensitive, fast response and high efficient carbon nanotube based gas sensor to detect N2O gas as an air pollutant. Our results could provide helpful information for the design and fabrication of the N2O sensors.

  18. Nitrous oxide flux to the atmosphere from the littoral zone of a boreal lake

    NASA Astrophysics Data System (ADS)

    Huttunen, Jari T.; Juutinen, Sari; Alm, Jukka; Larmola, Tuula; Hammar, Taina; Silvola, Jouko; Martikainen, Pertti J.

    2003-07-01

    The surface-atmospheric exchange of nitrous oxide (N2O) was investigated in the vegetated littoral zone of a eutrophied midboreal lake (Lake Kevätön, Finland) with a static chamber technique. During a dry summer (three to six samplings per site), the meadow site and two marsh sites in the temporarily flooded eulittoral zone and the Phragmites australis-dominated site in the continuously flooded infralittoral zone had mean daytime N2O-N emissions from 11 ± 7 to 22 ± 7 μg m-2 h-1, whereas the Nuphar lutea-dominated site in the infralittoral zone had a mean N2O flux close to zero. During a wet summer (13-14 samplings per site), the mean daytime N2O-N fluxes ranged from 4 ± 1 to 15 ± 5 μg m-2 h-1 at the three eulittoral sites and were negligible at the two infralittoral sites. The littoral zone occupied 26% of the lake area but was estimated to account for most of the N2O emissions from the lake. The studied eulittoral zone, which did not have adjacent nitrogen fertilization, exhibited higher N2O emissions during the summer than seen in northern natural ecosystems in general, including peatlands, forests, and the pelagic regions of lakes. Thus in lake-rich landscapes the littoral zone and other lake-associated wetlands must be considered as potential sources of atmospheric N2O. An assessment of their atmospheric importance requires further data on the N2O fluxes and their regulation in different littoral areas and on the total littoral coverage, neither of which is yet available.

  19. Impact of Cover Cropping and Landscape Positions on Nitrous Oxide Emissions in Northeastern Agroecosystems

    NASA Astrophysics Data System (ADS)

    Han, Z.; Walter, M. T.; Drinkwater, L. E.

    2015-12-01

    Studies investigating agricultural nitrous oxide (N2O) emissions tend to rely on plot-scale experiments. However, to understand the impacts of agricultural practices at a larger scale, it is essential to consider the variability of landscape characteristics along with management treatments. This study compared N2O emissions from a fertilizer-based, conventionally managed farm and an organically managed farm that uses legume cover crops as a primary nutrient source. The objective of the study was to assess how management regimes and slope positions interact to impact N2O emissions and soil characteristics. The field experiment was conducted in two adjacent grain farms in upstate New York that both have been under consistent management for 20 years. In the organic farm, red clover was frost-seeded into a winter grain (spelt), and then incorporated in the spring as a nutrient source for the subsequent corn plants. In contrast, the conventionally managed farm used inorganic fertilizer as the nutrient source. Gas measurement was conducted at two landscape positions at both farms: 1) shoulder and 2) toeslope positions. Comparable N2O emissions were found in the clover-corn phase in the organic site and the bare fallow-corn phase in the conventional site. The spelt-corn phase in the organic farm had the lowest N2O emissions. Soil nitrate concentration was the best predictor for seasonal average N2O emissions. The impact of landscape position on N2O emissions was only found in the conventional site, which was driven by higher denitrfication at toeslopes. In the organic farm, such effect was confounded by higher clover biomass at shoulder slopes. Our study shows that the impact of landscape characteristics on N2O emissions could differ across sites based on the complex interplay between environmental conditions and management.

  20. Global land-atmosphere exchange of methane and nitrous oxide: magnitude and spatiotemporal patterns

    NASA Astrophysics Data System (ADS)

    Tian, H.; Chen, G.; Lu, C.; Xu, X.; Ren, W.; Banger, K.; Zhang, B.; Tao, B.; Pan, S.; Liu, M.; Zhang, C.

    2013-12-01

    Methane (CH4) and nitrous oxide (N2O) are two most important greenhouse gases after carbon dioxide, but their regional and global budgets are far from certain, which is largely owing to uncertainties in scaling up field measurements as well as the poor model representation of processes and factors governing CH4 and N2O exchange between the terrestrial biosphere and atmosphere. In this study, we applied a process-based, coupled biogeochemical model (DLEM - the Dynamic Land Ecosystem Model) to estimate the magnitudes, spatial and temporal patterns of CH4 and N2O fluxes as driven by multiple environmental changes including climate variability, rising atmospheric CO2, increasing nitrogen deposition, tropospheric ozone pollution, land use change and nitrogen fertilizer use. The estimated CH4 and N2O emissions from global land ecosystems were 169.43 ± 32.92 Tg C yr-1 and 12.52 ± 1.52 Tg N yr-1, respectively. Our simulations have indicated a significant (P < 0.01) increasing trend for CH4 (0.75 ± 0.08 Tg C yr-1) and N2O (0.14 ± 0.02 Tg N yr-1) during 1981-2010. CH4 and N2O emissions increased significantly in most climatic zones and continents, especially in tropical region and Asia. The most rapid increase in CH4 emission was found in wetlands (including rice fields and natural wetlands) owing to increased rice field area and climate change; N2O emission increased substantially for all the biome types and the largest increase occurred in upland crops owing to increasing air temperature and nitrogen fertilizer use. Given large increase in CH4 and N2O emission at global scale, we suggest that these two gases together with CO2 have to be simultaneously considered when evaluating if a policy is effective or efficient to reduce global warming in the future.

  1. Microbial Abundances Predict Methane and Nitrous Oxide Fluxes from a Windrow Composting System.

    PubMed

    Li, Shuqing; Song, Lina; Gao, Xiang; Jin, Yaguo; Liu, Shuwei; Shen, Qirong; Zou, Jianwen

    2017-01-01

    Manure composting is a significant source of atmospheric methane (CH4) and nitrous oxide (N2O) that are two potent greenhouse gases. The CH4 and N2O fluxes are mediated by methanogens and methanotrophs, nitrifying and denitrifying bacteria in composting manure, respectively, while these specific bacterial functional groups may interplay in CH4 and N2O emissions during manure composting. To test the hypothesis that bacterial functional gene abundances regulate greenhouse gas fluxes in windrow composting systems, CH4 and N2O fluxes were simultaneously measured using the chamber method, and molecular techniques were used to quantify the abundances of CH4-related functional genes (mcrA and pmoA genes) and N2O-related functional genes (amoA, narG, nirK, nirS, norB, and nosZ genes). The results indicate that changes in interacting physicochemical parameters in the pile shaped the dynamics of bacterial functional gene abundances. The CH4 and N2O fluxes were correlated with abundances of specific compositional genes in bacterial community. The stepwise regression statistics selected pile temperature, mcrA and NH4(+) together as the best predictors for CH4 fluxes, and the model integrating nirK, nosZ with pmoA gene abundances can almost fully explain the dynamics of N2O fluxes over windrow composting. The simulated models were tested against measurements in paddy rice cropping systems, indicating that the models can also be applicable to predicting the response of CH4 and N2O fluxes to elevated atmospheric CO2 concentration and rising temperature. Microbial abundances could be included as indicators in the current carbon and nitrogen biogeochemical models.

  2. Microbial Abundances Predict Methane and Nitrous Oxide Fluxes from a Windrow Composting System

    PubMed Central

    Li, Shuqing; Song, Lina; Gao, Xiang; Jin, Yaguo; Liu, Shuwei; Shen, Qirong; Zou, Jianwen

    2017-01-01

    Manure composting is a significant source of atmospheric methane (CH4) and nitrous oxide (N2O) that are two potent greenhouse gases. The CH4 and N2O fluxes are mediated by methanogens and methanotrophs, nitrifying and denitrifying bacteria in composting manure, respectively, while these specific bacterial functional groups may interplay in CH4 and N2O emissions during manure composting. To test the hypothesis that bacterial functional gene abundances regulate greenhouse gas fluxes in windrow composting systems, CH4 and N2O fluxes were simultaneously measured using the chamber method, and molecular techniques were used to quantify the abundances of CH4-related functional genes (mcrA and pmoA genes) and N2O-related functional genes (amoA, narG, nirK, nirS, norB, and nosZ genes). The results indicate that changes in interacting physicochemical parameters in the pile shaped the dynamics of bacterial functional gene abundances. The CH4 and N2O fluxes were correlated with abundances of specific compositional genes in bacterial community. The stepwise regression statistics selected pile temperature, mcrA and NH4+ together as the best predictors for CH4 fluxes, and the model integrating nirK, nosZ with pmoA gene abundances can almost fully explain the dynamics of N2O fluxes over windrow composting. The simulated models were tested against measurements in paddy rice cropping systems, indicating that the models can also be applicable to predicting the response of CH4 and N2O fluxes to elevated atmospheric CO2 concentration and rising temperature. Microbial abundances could be included as indicators in the current carbon and nitrogen biogeochemical models. PMID:28373862

  3. Non-Growing Season Dynamics of Nitrous Oxide Emissions From Cropped Land in Southern Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Zurbrigg, M. E.; Petrone, R. M.; English, M. C.; Spoelstra, J.; Macrae, M. L.

    2009-05-01

    As atmospheric nitrous oxide (N2O) is increasing at a rate of 0.3% per annum and has a global warming potential 300 times greater than that of carbon dioxide (CO2), it is crucial to understand the dynamics of anthropogenic emissions of