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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. PMID:22594516

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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. PMID:26658648

  8. 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

  9. 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.

  10. Does zinc in livestock wastewater reduce nitrous oxide (N2O) emissions from mangrove soils?

    PubMed

    Chen, Guang C; Tam, Nora F Y; Ye, Yong

    2014-11-15

    Zinc (Zn) affects nitrogen cycling but the effect of Zn in wastewater on the emission of nitrous oxide (N2O) from the soil has not been reported. This study compared N2O emissions from mangrove soil receiving livestock wastewater containing various Zn(2+) concentrations and evaluated how long the effects of Zn would last in these soil-wastewater microcosms. Significant increases in N2O flux were observed soon after the discharge of wastewater with a low Zn content. On the other hand, the flux was reduced significantly in the wastewater with high Zn levels but such inhibitory effect was not observed after tidal flushing. Continuous monitoring of the N2O fluxes also confirmed that the inhibitory effect of Zn was confined within a few hours and the fluxes recovered in 6-9 h after the wastewater was completely drained away. These results indicated that the inhibitory effect of Zn on N2O fluxes occurred immediately after wastewater discharge and disappeared gradually. In the surface soil, nitrate levels increased with the addition of wastewater but there was no significant accumulation of NH4(+)-N, irrespective of the Zn content in the wastewater. The study also showed that nitrification potential and immediate N2O emissions were inhibited by high Zn levels in the soil, but the total oxidation of ammonium to nitrate was not affected.

  11. Does zinc in livestock wastewater reduce nitrous oxide (N2O) emissions from mangrove soils?

    PubMed

    Chen, Guang C; Tam, Nora F Y; Ye, Yong

    2014-11-15

    Zinc (Zn) affects nitrogen cycling but the effect of Zn in wastewater on the emission of nitrous oxide (N2O) from the soil has not been reported. This study compared N2O emissions from mangrove soil receiving livestock wastewater containing various Zn(2+) concentrations and evaluated how long the effects of Zn would last in these soil-wastewater microcosms. Significant increases in N2O flux were observed soon after the discharge of wastewater with a low Zn content. On the other hand, the flux was reduced significantly in the wastewater with high Zn levels but such inhibitory effect was not observed after tidal flushing. Continuous monitoring of the N2O fluxes also confirmed that the inhibitory effect of Zn was confined within a few hours and the fluxes recovered in 6-9 h after the wastewater was completely drained away. These results indicated that the inhibitory effect of Zn on N2O fluxes occurred immediately after wastewater discharge and disappeared gradually. In the surface soil, nitrate levels increased with the addition of wastewater but there was no significant accumulation of NH4(+)-N, irrespective of the Zn content in the wastewater. The study also showed that nitrification potential and immediate N2O emissions were inhibited by high Zn levels in the soil, but the total oxidation of ammonium to nitrate was not affected. PMID:25171729

  12. Using natural isotopic abundances to determine the source of nitrous oxide (N2O) emissions

    NASA Astrophysics Data System (ADS)

    Mothet, A.; Sebilo, M.; Laverman, A. M.; Vaury, V.; Mariotti, A.

    2012-04-01

    Numerous greenhouse gas studies have focused on carbon dioxide (CO2), whereas nitrous oxide (N2O) also plays a major role in global warming. Indeed, while nitrous oxide is 1000 times less concentrated than CO2 in the atmosphere, it is 300 times more efficient in terms of global warming potential. In addition, its atmospheric concentration increases with 0,3 % per year. According to the literature, nitrous oxide is produced, in soils and sediments, by two major processes: (1) Nitrification, mediated by autotrophic nitrifying bacteria under oxic conditions; (2) Denitrification, mediated by heterotrophic denitrifying bacteria under anoxic conditions. Denitrification induces intensive, localized and instantaneous fluxes. N2O emissions can be easily measured and modeled. In contrast, nitrification induces weak emissions, but spatially and temporally extended. Therefore, this process could represent a large potential of N2O emissions from soils and sediments. The study of isotopomer's isotopic composition of N2O, i.e. the intramolecular distribution or site preference (SP) determined by 15N measurement allows the determination of the origin of N2O emissions (nitrification vs. denitrification). Recent studies on pure cultures have showed that SP associated with nitrification is 35 ‰ while SP associated with denitrification is 0 ‰. The aim of this study was to determine SP associated with denitrification in soils and sediments, taking into account the environmental denitrifying bacterial communities, and under different environmental variables. To this end, flow-through reactors were used to determine denitrification rates at different temperatures and varying substrate (nitrate) concentrations. Site preference was measured for the different experiments. Different experiments of denitrification were realized in sediment flow through reactors under denitrifying conditions (anoxia, presence of organic matter and nitrate). We used acetylene (25°C) to block the enzyme

  13. Nitrous oxide (N2O) emissions from waste and biomass to energy plants.

    PubMed

    Fernandez Gutierrez, Maria Jose; Baxter, David; Hunter, Christopher; Svoboda, Karel

    2005-04-01

    Following the Kyoto protocol with respect to reducing emissions of greenhouse gases emissions, and EU energy policy and sustainability in waste management, there has been an increased interest in the reduction of emissions from waste disposal operations. From the point of view of nitrous oxide (N2O) emissions, waste incineration and waste co-combustion are very acceptable methods for waste disposal. In order to achieve very low N2O emissions from waste incineration, particularly for waste with higher nitrogen content (e.g. sewage sludge), two factors are important: temperature of incineration over 900 degrees C and avoiding the selective non-catalytic reduction (SNCR) de-NO(X) method based on urea or ammonia treatments. The more modern selective catalytic reduction (SCR) systems for de-NO(X) give rise to negligible sources of N2O.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. 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

  20. 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

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 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... N2O-N/kg Kjdl N) Manure management system component N2O emission factor Uncovered anaerobic lagoon...

  1. Influence of biofilm thickness on nitrous oxide (N2O) emissions from denitrifying fluidized bed bioreactors (DFBBRs).

    PubMed

    Eldyasti, Ahmed; Nakhla, George; Zhu, Jesse

    2014-12-20

    Nitrous oxide (N2O) is a significant anthropogenic greenhouse gas emitted from biological nutrient removal (BNR) processes. This study tries to get a deeper insight into N2O emissions from denitrifying fluidized bed bioreactors (DFBBRs) and its relationship to the biofilm thickness, diffusivity, and reaction rates. The DFBBR was operated at two different organic and nitrogen loading rates of 5.9–7 kg COD/(m3 d) and 1.2–2 kg N/(m3 d), respectively. Results showed that the N2O conversion rate from the DFBBR at a biofilm thickness of 680 μm was 0.53% of the total influent nitrogen loading while at the limited COD and a biofilm thickness of 230 μm, the N2O conversion rate increased by 196–1.57% of the influent nitrogen loading concomitant with a sevenfold increase in liquid nitrite concentration. Comparing the N2O emissions at different biofilm thickness showed that the N2O emission decreased exponentially with biofilm thickness due to the retention of slow growth denitrifiers and the limited diffusivity of N2O.

  2. Nitrous oxide (N(2)O) requires the N-methyl-D-aspartate receptor for its action in Caenorhabditis elegans.

    PubMed

    Nagele, P; Metz, L B; Crowder, C M

    2004-06-01

    Nitrous oxide (N(2)O, also known as laughing gas) and volatile anesthetics (VAs), the original and still most widely used general anesthetics, produce anesthesia by ill-defined mechanisms. Electrophysiological experiments in vertebrate neurons have suggested that N(2)O and VAs may act by distinct mechanisms; N(2)O antagonizes the N-methyl-d-aspartate (NMDA) subtype of glutamate receptors, whereas VAs alter the function of a variety of other synaptic proteins. However, no genetic or pharmacological experiments have demonstrated that any of these in vitro actions are responsible for the behavioral effects of either class of anesthetics. By using genetic tools in Caenorhabditis elegans, we tested whether the action of N(2)O requires the NMDA receptor in vivo and whether its mechanism is shared by VAs. Distinct from the action of VAs, N(2)O produced behavioral defects highly specific and characteristic of that produced by loss-of-function mutations in both NMDA and non-NMDA glutamate receptors. A null mutant of nmr-1, which encodes a C. elegans NMDA receptor, was completely resistant to the behavioral effects of N(2)O, whereas a non-NMDA receptor-null mutant was normally sensitive. The N(2)O-resistant nmr-1(null) mutant was not resistant to VAs. Likewise, VA-resistant mutants had wild-type sensitivity to N(2)O. Thus, the behavioral effects of N(2)O require the NMDA receptor NMR-1, consistent with the hypothesis formed from vertebrate electrophysiological data that a major target of N(2)O is the NMDA receptor. PMID:15159532

  3. 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

  4. 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.

  5. 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

  6. Increasing the availability of l-arginine and nitric oxide increases sensitivity of nitrous oxide (N2O)-insensitive inbred mice to N2O-induced antinociception.

    PubMed

    Chung, Eunhee; Ohgami, Yusuke; Quock, Raymond M

    2016-07-01

    Nitrous oxide (N2O)-induced antinociception in mice is dependent on the neuromodulator nitric oxide (NO). In contrast to C57BL/6J (B6) mice, DBA/2J (D2) mice fail to respond to N2O with a robust antinociceptive response or with an increase in brain nitric oxide synthase (NOS) enzyme activity, suggesting that failure of D2 mice to respond to N2O might result from a deficit of NO function. Therefore, it was of interest to determine whether increasing the availability of NO might increase sensitivity of D2 mice to N2O. Male D2 mice were pretreated with sub-antinociceptive intracerebroventricular doses of the NO donor 3-morpholinosydnoimine or the NO precursor l-arginine then assessed for responsiveness to N2O-induced antinociception using the acetic acid abdominal constriction test. Both pretreatments increased the antinociceptive responsiveness of D2 mice to N2O. These results indicate that the NOS enzyme in D2 mice is functional and that the deficit in NO function that obstructs sensitivity to N2O-induced antinociception may lie in availability or utilization of l-arginine. PMID:27496065

  7. Optimization of operation conditions for the mitigation of nitrous oxide (N2O) emissions from aerobic nitrifying granular sludge system.

    PubMed

    Liu, Rui-Ting; Wang, Xin-Hua; Zhang, Yan; Wang, Ming-Yu; Gao, Ming-Ming; Wang, Shu-Guang

    2016-05-01

    The optimization of operation parameters is a key consideration to minimize nitrous oxide (N2O) emissions in biological nitrogen removal processes. So far, different parameters have only been investigated individually, making it difficult to compare their specific effects and combined influences. In this study, we applied the Plackett-Burman (PB) multifactorial experimental design and response surface methodology (RSM) analysis to find the optimized condition for the mitigation of N2O release in a nitrifying granular sludge system. Seven parameters (temperature, pH, feeding strategy, C/N ratio, aeration rate, Cu(2+) concentration, and aeration mode) were tested in parallel. Five of them (other than chemical oxygen demand/nitrogen (C/N) ratio and Cu(2+) concentration) were selected as influential factors. Since the type of feeding strategies and aeration modes cannot be quantified, continuous feed strategy and anoxic/oxic aeration mode were applied for the following study. Influences of temperature, pH, and aeration rate on N2O emissions were tested with RSM analysis to further investigate the mutual interactions among the parameters and to identify the optimal values that would minimize N2O release. Results showed the minimum emission value could be obtained under the temperature of 22.3 °C, pH of 7.1 and aeration rate of 0.20 m(3)/h. Predicted results were then verified by subsequent validation experiments. The estimated N2O emission value of each design by RSM was also observed in good relationships with experimental result.

  8. Vertical Profiles as Observational Constraints on Nitrous Oxide (N2O) Emissions in an Agricultural Region

    NASA Astrophysics Data System (ADS)

    Pusede, S.; Diskin, G. S.

    2015-12-01

    We use diurnal variability in near-surface N2O vertical profiles to derive N2O emission rates. Our emissions estimates are ~3 times greater than are accounted for by inventories, a discrepancy in line with results from previous studies using different approaches. We quantify the surface N2O concentration's memory of local surface emissions on previous days to be 50-90%. We compare measured profiles both over and away from a dense N2O source region in the San Joaquin Valley, finding that profile shapes, diurnal variability, and changes in integrated near-surface column abundances are distinct according to proximity to source areas. To do this work, we use aircraft observations from the wintertime DISCOVER-AQ project in California's San Joaquin Valley, a region of intense agricultural activity.

  9. Evidence for Involvement of Gut-Associated Denitrifying Bacteria in Emission of Nitrous Oxide (N2O) by Earthworms Obtained from Garden and Forest Soils

    PubMed Central

    Matthies, Carola; Grießhammer, Anja; Schmittroth, Martina; Drake, Harold L.

    1999-01-01

    Earthworms (Aporrectodea caliginosa, Lumbricus rubellus, and Octolasion lacteum) obtained from nitrous oxide (N2O)-emitting garden soils emitted 0.14 to 0.87 nmol of N2O h−1 g (fresh weight)−1 under in vivo conditions. L. rubellus obtained from N2O-emitting forest soil also emitted N2O, which confirmed previous observations (G. R. Karsten and H. L. Drake, Appl. Environ. Microbiol. 63:1878–1882, 1997). In contrast, commercially obtained Lumbricus terrestris did not emit N2O; however, such worms emitted N2O when they were fed (i.e., preincubated in) garden soils. A. caliginosa, L. rubellus, and O. lacteum substantially increased the rates of N2O emission of garden soil columns and microcosms. Extrapolation of the data to in situ conditions indicated that N2O emission by earthworms accounted for approximately 33% of the N2O emitted by garden soils. In vivo emission of N2O by earthworms obtained from both garden and forest soils was greatly stimulated when worms were moistened with sterile solutions of nitrate or nitrite; in contrast, ammonium did not stimulate in vivo emission of N2O. In the presence of nitrate, acetylene increased the N2O emission rates of earthworms; in contrast, in the presence of nitrite, acetylene had little or no effect on emission of N2O. In vivo emission of N2O decreased by 80% when earthworms were preincubated in soil supplemented with streptomycin and tetracycline. On a fresh weight basis, the rates of N2O emission of dissected earthworm gut sections were substantially higher than the rates of N2O emission of dissected worms lacking gut sections, indicating that N2O production occurred in the gut rather than on the worm surface. In contrast to living earthworms and gut sections that produced N2O under oxic conditions (i.e., in the presence of air), fresh casts (feces) from N2O-emitting earthworms produced N2O only under anoxic conditions. Collectively, these results indicate that gut-associated denitrifying bacteria are responsible for

  10. Evidence for involvement of gut-associated denitrifying bacteria in emission of nitrous oxide (N(2)O) by earthworms obtained from garden and forest soils.

    PubMed

    Matthies, C; Griesshammer, A; Schmittroth, M; Drake, H L

    1999-08-01

    Earthworms (Aporrectodea caliginosa, Lumbricus rubellus, and Octolasion lacteum) obtained from nitrous oxide (N(2)O)-emitting garden soils emitted 0.14 to 0.87 nmol of N(2)O h(-1) g (fresh weight)(-1) under in vivo conditions. L. rubellus obtained from N(2)O-emitting forest soil also emitted N(2)O, which confirmed previous observations (G. R. Karsten and H. L. Drake, Appl. Environ. Microbiol. 63:1878-1882, 1997). In contrast, commercially obtained Lumbricus terrestris did not emit N(2)O; however, such worms emitted N(2)O when they were fed (i.e., preincubated in) garden soils. A. caliginosa, L. rubellus, and O. lacteum substantially increased the rates of N(2)O emission of garden soil columns and microcosms. Extrapolation of the data to in situ conditions indicated that N(2)O emission by earthworms accounted for approximately 33% of the N(2)O emitted by garden soils. In vivo emission of N(2)O by earthworms obtained from both garden and forest soils was greatly stimulated when worms were moistened with sterile solutions of nitrate or nitrite; in contrast, ammonium did not stimulate in vivo emission of N(2)O. In the presence of nitrate, acetylene increased the N(2)O emission rates of earthworms; in contrast, in the presence of nitrite, acetylene had little or no effect on emission of N(2)O. In vivo emission of N(2)O decreased by 80% when earthworms were preincubated in soil supplemented with streptomycin and tetracycline. On a fresh weight basis, the rates of N(2)O emission of dissected earthworm gut sections were substantially higher than the rates of N(2)O emission of dissected worms lacking gut sections, indicating that N(2)O production occurred in the gut rather than on the worm surface. In contrast to living earthworms and gut sections that produced N(2)O under oxic conditions (i.e., in the presence of air), fresh casts (feces) from N(2)O-emitting earthworms produced N(2)O only under anoxic conditions. Collectively, these results indicate that gut

  11. 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.

  12. 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

  13. 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.

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

    PubMed

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

    2016-06-25

    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

  15. 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.

  16. 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.

  17. 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. PMID:26551878

  18. 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.

  19. 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

  20. Lake acidification and oxygen depletion may synergistically enhance nitrous oxide (N2O) production by nitrifier denitrification in a subalpine lake

    NASA Astrophysics Data System (ADS)

    Frame, C. H.; Goepfert, T. J.; Rollog, M.; Lehmann, M. F.

    2013-12-01

    Ammonia-oxidizing microorganisms are an important source of the greenhouse gas nitrous oxide (N2O). They produce N2O through two mechanisms: by the decomposition of an intermediate in the ammonia (NH3) oxidation reaction, and by nitrifier denitrification, which is the enzymatic reduction of nitrite (NO2-). We investigated the impact of water pH and oxygen (O2) concentrations on rates of N2O production by these two mechanisms in the water column of Lake Lugano, a subalpine lake between Switzerland and Italy. Acidification of natural waters is known to reduce the rate of ammonia oxidation by forcing the equilibrium NH4+ ←→ NH3 + H+ away from NH3, the form that is preferentially taken up by ammonia oxidizers. In turn, this reduces the rate of N2O production by decomposition of the reaction intermediate during ammonia oxidation. However, using 15NH4+ and 15NO2- tracer additions during lake water incubations, we showed that reducing the pH from in situ values of 7.5 to 8 down to 6 to 7 actually increased the rate of N2O production by nitrifier denitrification. Hypoxia is thought to enhance N2O production by nitrifier denitrification. We did not observe nitrifier denitrification in incubations that were fully oxic (partial pressure of O2 = 20.9%) or had reduced O2 (partial pressure = 12%). However, when the incubation pH was lowered and the O2 reduced to 12%, N2O production by nitrifier denitrification was much greater than it was in incubations where only the pH was reduced or only the O2 concentration was reduced. Water for these experiments was drawn from depths just below the epilimnion of the monomictic south basin of Lugano, an environment whose pH, O2, and nutrient concentrations fluctuate throughout the water column on a seasonal basis and change in the shallower depths on a daily basis. We discuss the implications of these changes for the flux of shallow N2O into the atmosphere and a possible mechanism that explains the synergistic influence of O2 and pH on

  1. 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

  2. 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

  3. Emissions of nitrous oxide (N2O) from a tidal, freshwater river, the Hudson River, New York.

    PubMed

    Cole, J J; Caraco, N F

    2001-03-15

    Rivers receive a significant fraction of the anthropogenic nitrogen applied to the world's watersheds. Environmental conditions in rivers should be conducive to the formation of N2O, and recent models suggest that rivers could constitute up to 25% of the anthropogenic contribution of N2O to the atmosphere. Few direct measurements exist, however, of N2O flux between rivers, especially large rivers, and the overlying atmosphere. We measured the concentration of N2O over a 2-year period in a large, tidal, freshwater river. We coupled these measurements with a physical model of gas exchange based on inert gas tracer additions to this river and computed the flux of N2O to the atmosphere. The tidal, freshwater Hudson River is persistently supersaturated in N2O with respect to the atmosphere, with average partial pressure of N2O (pN2O) of 0.58 muatm or about 185% of atmospheric equilibrium. At all times during a 2-year cycle and at all locations sampled along a 200 km stretch of the river, the river was a net source of N2O to the atmosphere. We estimate that the tidal, freshwater Hudson River contributes 0.056 g of N2O-N m(-2) to the atmosphere annually. Despite relatively high concentrations of NO3 in the Hudson River, the tidal, freshwater river is a minor source of N2O in comparison to other rivers for which estimates exist and to components of its own watershed. The river itself accounts for only 1.3% of the total N2O contribution to the atmosphere that occurs in the Hudson watershed. PMID:11347946

  4. Nitrous oxide (N2O): the dominant ozone-depleting substance emitted in the 21st century.

    PubMed

    Ravishankara, A R; Daniel, John S; Portmann, Robert W

    2009-10-01

    By comparing the ozone depletion potential-weighted anthropogenic emissions of N2O with those of other ozone-depleting substances, we show that N2O emission currently is the single most important ozone-depleting emission and is expected to remain the largest throughout the 21st century. N2O is unregulated by the Montreal Protocol. Limiting future N2O emissions would enhance the recovery of the ozone layer from its depleted state and would also reduce the anthropogenic forcing of the climate system, representing a win-win for both ozone and climate.

  5. 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.

  6. 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.

  7. Comparison of nitrous oxide (N2O) analyzers for high-precision measurements of atmospheric mole fractions

    NASA Astrophysics Data System (ADS)

    Lebegue, Benjamin; Schmidt, Martina; Ramonet, Michel; Wastine, Benoit; Yver Kwok, Camille; Laurent, Olivier; Belviso, Sauveur; Guemri, Ali; Philippon, Carole; Smith, Jeremiah; Conil, Sebastien

    2016-03-01

    Over the last few decades, in situ measurements of atmospheric N2O mole fractions have been performed using gas chromatographs (GCs) equipped with electron capture detectors. This technique, however, becomes very challenging when trying to detect the small variations of N2O as the detectors are highly nonlinear and the GCs at remote stations require a considerable amount of maintenance by qualified technicians to maintain good short-term and long-term repeatability. With new robust optical spectrometers now available for N2O measurements, we aim to identify a robust and stable analyzer that can be integrated into atmospheric monitoring networks, such as the Integrated Carbon Observation System (ICOS). In this study, we present the most complete comparison of N2O analyzers, with seven analyzers that were developed and commercialized by five different companies. Each instrument was characterized during a time period of approximately 8 weeks. The test protocols included the characterization of the short-term and long-term repeatability, drift, temperature dependence, linearity and sensitivity to water vapor. During the test period, ambient air measurements were compared under field conditions at the Gif-sur-Yvette station. All of the analyzers showed a standard deviation better than 0.1 ppb for the 10 min averages. Some analyzers would benefit from improvements in temperature stability to reduce the instrument drift, which could then help in reducing the frequency of calibrations. For most instruments, the water vapor correction algorithms applied by companies are not sufficient for high-precision atmospheric measurements, which results in the need to dry the ambient air prior to analysis.

  8. 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.

  9. Potential role of Thermus thermophilus and T. oshimai in high rates of nitrous oxide (N2O) production in ∼80 °C hot springs in the US Great Basin.

    PubMed

    Hedlund, B P; McDonald, A I; Lam, J; Dodsworth, J A; Brown, J R; Hungate, B A

    2011-11-01

    Ambient nitrous oxide (N(2)O) emissions from Great Boiling Spring (GBS) in the US Great Basin depended on temperature, with the highest flux, 67.8 ± 2.6 μmol N(2)O-N m(-2) day(-1) , occurring in the large source pool at 82 °C. This rate of N(2)O production contrasted with negligible production from nearby soils and was similar to rates from soils and sediments impacted with agricultural fertilizers. To investigate the source of N(2)O, a variety of approaches were used to enrich and isolate heterotrophic micro-organisms, and isolates were screened for nitrate reduction ability. Nitrate-respiring isolates were identified by 16S rRNA gene sequencing as Thermus thermophilus (31 isolates) and T. oshimai (three isolates). All isolates reduced nitrate to N(2)O but not to dinitrogen and were unable to grow with N(2)O as a terminal electron acceptor. Representative T. thermophilus and T. oshimai strains contained genes with 96-98% and 93% DNA identity, respectively, to the nitrate reductase catalytic subunit gene (narG) of T. thermophilus HB8. These data implicate T. thermophilus and T. oshimai in high flux of N(2)O in GBS and raise questions about the genetic basis of the incomplete denitrification pathway in these organisms and on the fate of biogenic N(2)O in geothermal environments.

  10. 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. PMID:25621437

  11. Isotopic Signature of N2O Produced by Marine Ammonia-Oxidizing Archaea

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

    The ocean is an important global source of nitrous oxide (N2O), a greenhouse gas that contributes to stratospheric ozone destruction. Bacterial nitrification and denitrification are thought to be the primary sources of marine N2O, but the isotopic signatures of N2O produced by these processes are not consistent with the marine contribution to the global N2O budget. Based on enrichment cultures, we report that archaeal ammonia oxidation also produces N2O. Natural-abundance stable isotope measurements indicate that the produced N2O had bulk δ15N and δ18O values higher than observed for ammonia-oxidizing bacteria but similar to the δ15N and δ18O values attributed to the oceanic N2O source to the atmosphere. Our results suggest that ammonia-oxidizing archaea may be largely responsible for the oceanic N2O source.

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

    PubMed

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

    2011-09-01

    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. PMID:21798895

  13. 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.

  14. 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...

  15. 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...

  16. 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...

  17. Reducing N2O Emission from a Domestic-Strength Nitrifying Culture by Free Nitrous Acid-Based Sludge Treatment.

    PubMed

    Wang, Dongbo; Wang, Qilin; Laloo, Andrew Elohim; Yuan, Zhiguo

    2016-07-19

    An increase of nitrite in the domestic-strength range is generally recognized to stimulate nitrous oxide (N2O) production by ammonia-oxidizing bacteria (AOB). It was found in this study, however, that N2O emission from a mainstream nitritation system (cyclic nitrite = 25-45 mg of N/L) that was established by free nitrous acid (FNA)-based sludge treatment was not higher but much lower than that from the initial nitrifying system with full conversion of NH4(+)-N to NO3(-)-N. Under dissolved oxygen (DO) levels of 2.5-3.0 mg/L, N2O emission from the nitritation stage was 76% lower than that from the initial stage. Even when the DO level was reduced to 0.3-0.8 mg/L, N2O emission from the nitritation stage was still 40% lower. An investigation of the mechanism showed that FNA treatment caused a shift of the stimulation threshold of nitrite on N2O emission. At the nitritation stage, the maximal N2O emission factor occurred at ∼16 mg of N/(L of nitrite). However, it increased with increasing nitrite in the range of 0-56 mg of N/L at the initial stage. FNA treatment decreased the biomass-specific N2O production rate, suggesting that the enzymes relevant to nitrifier denitrification were inhibited. Microbial analysis revealed that FNA treatment decreased the microbial community diversity but increased the abundances of AOB and denitrifiers. PMID:27294698

  18. 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

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

    PubMed

    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 [δ(15)N(bulk), δ(18)O, and SP (intramolecular (15)N 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. δ(15)N(bulk) and δ(18)O 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

  20. Collisional activation of N2O decomposition and CO oxidation reactions on isolated rhodium clusters.

    PubMed

    Parry, Imogen S; Kartouzian, Aras; Hamilton, Suzanne M; Balaj, O Petru; Beyer, Martin K; Mackenzie, Stuart R

    2013-09-12

    The reactions of nitrous oxide decorated rhodium clusters, RhnN2O(+) (n = 5, 6), have been studied by Fourier transform ion cyclotron resonance mass spectrometry. Collision induced dissociation with Ar is shown to lead to one of two processes; desorption of the intact N2O moiety (indicating molecular adsorption in the parent cluster) or N2O decomposition liberating molecular nitrogen with the latter becoming increasingly dominant at higher collision energies. Consistent with the results of earlier studies, which employed infrared excitation [Hermes, A. C.; et al. J. Phys. Chem. Lett. 2011, 2, 3053], Rh5ON2O(+) is observed to behave qualitatively differently to Rh5N2O(+) with decomposition of the nitrous oxide dominating the chemistry of the former. In other experiments, the reactivity of RhnN2O(+) clusters with CO has been studied. Chemisorption of (13)CO is calculated to deposit ca. 2 eV into the parent cluster, initiating a range of chemical processes on the cluster surface, which are fit to a simple reaction mechanism. Clear differences are again observed in the reaction branching ratios for Rh5N2O(+) and Rh6N2O(+) parent cluster ions. For the n = 5 cluster, the combined N2O reduction/CO oxidation is the most significant reaction channel, while the n = 6 cluster preferentially is oxidized to Rh6O(+) with loss of N2 and CO. Even larger differences are observed in the reactions of the N2O decorated cluster oxides, RhnON2O(+), for which more reaction possibilities arise. The results of all studies are discussed in relation to infrared driven processes on the same parent cluster species [Hamilton, S. M.; et al. J. Am. Chem. Soc. 2010, 132, 1448; J. Phys. Chem. A, 2011, 115, 2489].

  1. 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...

  2. Synthetic chemistry with nitrous oxide.

    PubMed

    Severin, Kay

    2015-10-01

    This review article summarizes efforts to use nitrous oxide (N2O, 'laughing gas') as a reagent in synthetic chemistry. The focus will be on reactions which are carried out in homogeneous solution under (relatively) mild conditions. First, the utilization of N2O as an oxidant is discussed. Due to the low intrinsic reactivity of N2O, selective oxidation reactions of highly reactive compounds are possible. Furthermore, it is shown that transition metal complexes can be used to catalyze oxidation reactions, in some cases with high turnover numbers. In the final part of this overview, the utilization of N2O as a building block for more complex molecules is discussed. It is shown that N2O can be used as an N-atom donor for the synthesis of interesting organic molecules such as triazenes and azo dyes. PMID:26104268

  3. CHARACTERIZATION OF NITROUS OXIDE EMISSION SOURCES

    EPA Science Inventory

    The report presents a global inventory of nitrous oxide (N2O) based on reevaluation of previous estimates and additions of previously uninventoried source categories. (NOTE: N2O is both a greenhouse gas and a precursor of nitric oxide (NO) which destroys stratospheric ozone.) The...

  4. 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...

  5. A search for interstellar nitrous oxide

    NASA Technical Reports Server (NTRS)

    Wilson, W. J.; Snyder, L. E.

    1981-01-01

    An extensive search for interstellar nitrous oxide (N2O) has been made at two different frequencies, 75.4 and 100.5 GHz, in a number of molecular sources. No N2O signal was detected; however, a number of other spectral lines including two new transitions of methyl formate and several new unidentified lines were measured.

  6. 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.

  7. 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.

  8. 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. PMID:24003604

  9. 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...

  10. 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...

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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. PMID:25179869

  16. 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.

  17. Isotope Effects Associated with N2O Production by Fungal and Bacterial Nitric Oxide Reductases: Implications for Enzyme Mechanisms

    NASA Astrophysics Data System (ADS)

    Hegg, E. L.; Yang, H.; Gandhi, H.; McQuarters, A.; Lehnert, N.; Ostrom, N. E.

    2014-12-01

    Nitrous oxide (N2O) is both a powerful greenhouse gas and a key participant in ozone destruction. Microbial activity accounts for over 70% of the N2O produced annually, and the atmospheric concentration of N2O continues to rise. Because the fungal and bacterial denitrification pathways are major contributors to microbial N2O production, understanding the mechanism by which NO is reduced to N2O will contribute to both N2O source tracing and quantification. Our strategy utilizes stable isotopes to probe the enzymatic mechanism of microbial N2O production. Although the use of stable isotopes to study enzyme mechanisms is not new, our approach is distinct in that we employ both measurements of isotopic preferences of purified enzyme and DFT calculations, thereby providing a synergistic combination of experimental and computational approaches. We analyzed δ18O, δ15Nα (central N atom in N2O), and δ15Nβ (terminal N atom) of N2O produced by purified fungal cytochrome P450 nitric oxide reductase (P450nor) from Histoplasma capsulatum as well as bacterial cytochrome c dependent nitric oxide reductase (cNOR) from Paracoccus denitrificans. P450nor exhibits an inverse kinetic isotope effect for Nβ (KIE = 0.9651) but a normal isotope effect for both Nα (KIE = 1.0127) and the oxygen atom (KIE = 1.0264). These results suggest a mechanism where NO binds to the ferric heme in the P450nor active site and becomes Nβ. Analysis of the NO-binding step indicated a greater difference in zero point energy in the transition state than the ground state, resulting in the inverse KIE observed for Nβ. Following protonation and rearrangement, it is speculated that this complex forms a FeIV-NHOH- species as a key intermediate. Our data are consistent with the second NO (which becomes Nα and O in the N2O product) attacking the FeIV-NHOH- species to generate a FeIII-N2O2H2 complex that enzymatically (as opposed to abiotically) breaks down to release N2O. Conversely, our preliminary data

  18. 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. PMID:27376009

  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. 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...

  1. Nitrous Oxide Production by Bacterioneuston

    NASA Astrophysics Data System (ADS)

    Moore, M.; Baggs, E. M.; Witte, U.; Maxwell, S.; Iain, S.

    2008-12-01

    Covering 70% of the Earth, the interface between the ocean and atmosphere, the sea surface microlayer, plays a key role in controlling the exchange of natural and anthropogenic materials. Knowledge of the specific role of the sea surface microlayer and its bacterial population, the bacterioneuston is currently limited. Denitrification is an important route of nitrogen loss from the marine environment. It is also both a sink and source of the greenhouse gas nitrous oxide. Here we investigated the role of denitrifying organisms in the sea-surface microlayer and their potential to lower net emissions of N2O by reducing to N2. Bacterioneuston was sampled from two sites in the Ythan Estuary and in Moray Firth at Cromarty during phytoplankton blooms in Autumn 2007 and Spring 2008 and obtained enrichment cultures from these. Incubation experiments were carried out over a 72 hour period, testing bacterioneuston cultures for N2O production using gas chromatography and nitrate, nitrite and ammonium concentrations. All of the enrichment cultures analysed produced significant quantities of N2O. Results of nitrate, nitrite and ammonium analysis were mixed. Some cultures showed a decrease in nitrate concentration possibly due to nitrate reduction by the bacterioneuston. However, an increase in the nitrate concentration measured with other cultures indicates that N2O production could be due to other nitrogen cycle processes other than denitrification, most likely ammonia oxidation. The results indicate that further research is necessary to establish which nitrogen cycle processes are being carried out the bacterioneuston cultures. Keywords: Denitrification; Bacterioneuston; Sea surface microlayer; Gas Chromatography (GC); Nitrous oxide

  2. AGRICULTURAL MANAGEMENT EFFECTS ON NITROUS OXIDE GAS EMISSIONS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) gas is produced by micro-organisms during nitrification and/or denitrification of fertilizer nitrogen in soil. Atmospheric emissions of N2O can be important from an agronomic standpoint since any escape of N from the soil represents N that cannot be utilized by the crop. Once in ...

  3. 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...

  4. 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...

  5. 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. PMID:26496821

  6. 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.

  7. 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...

  8. Sediment Nitrous Oxide Fluxes from Shore to Shelf

    NASA Astrophysics Data System (ADS)

    Fulweiler, R. W.; Heiss, E. M.; Morgan, E. J.

    2010-12-01

    Approximately 25% of global N2O emissions are estimated to come from the oceans. Importantly, although estuaries and coastal seas account for less than 20% of the global ocean area they may be responsible for more than half of the total N2O flux. Recently, it was reported that over 80% of aquatic N2O emissions are found in the Northern Hemisphere mid- latitudes. This has been attributed to the geographic distribution of fertilizer use, human population, and atmospheric N deposition. While the correlation between N loading and nitrous oxide production makes the coastal zone a probable hotspot for N2O emissions the environmental controls on N2O production are not known. In particular, the role of organic matter in regulating sediment N2O flux is unclear. Narragansett Bay and the neighboring Rhode Island Sound (RIS) and Block Island Sound (BIS) present a perfect system in which to examine the role of nitrogen and carbon loading on nitrous oxide production. A natural gradient of anthropogenic impact exists - from the heavily nitrogen enriched and highly productive Providence River Estuary out to the less N impacted, more oligotrophic RI Sound and BI Sound. As part of a larger study we measured nitrous oxide fluxes across the sediment water interface at five stations along this gradient. Ongoing field observations and experimental manipulations highlight the importance of organic matter (quality, timing, and magnitude) in regulating nitrous oxide fluxes. In some cases, sediment consumption of nitrous oxide has also been observed.

  9. A mesospheric source of nitrous oxide

    NASA Technical Reports Server (NTRS)

    Zipf, E. C.; Prasad, S. S.

    1982-01-01

    In the terrestrial atmosphere, nitrous oxide (N2O) has a major role in the chemistry of ozone. Current atmospheric models assume that N2O is produced only by fixation at the earth's surface and that there are no local sources in the stratosphere or mesosphere. It is pointed out here that a significant in situ N2O source does exist above 20 km due to the excitation of the metastable N2(A 3Sigma u +) state by resonance absorption of solar UV photons that penetrate deeply into the atmosphere through the 1,800-2,200 A O2-O3 window. This source significantly affects the NO altitude distribution in the mesosphere and, in the earth's prebiological atmosphere, made N2O an important stratospheric constituent.

  10. 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). PMID:25644626

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

    PubMed

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

    2014-05-01

    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), δ(15)N(bulk) and δ(18)O -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 (15)N-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

  12. 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

  13. 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...

  14. 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...

  15. 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

  16. 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. PMID:26258592

  17. 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.

  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. PMID:27483805

  19. 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.

  20. 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

  1. 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.

  2. Synthesis of azoimidazolium dyes with nitrous oxide.

    PubMed

    Tskhovrebov, Alexander G; Naested, Lara C E; Solari, Euro; Scopelliti, Rosario; Severin, Kay

    2015-01-19

    A new method for the synthesis of industrially important azoimidazolium dyes is presented. The procedure is based on a reagent which is rarely used in the context of synthetic organic chemistry: nitrous oxide ("laughing gas"). N2O is first coupled to N-heterocyclic carbenes. Subsequent reaction with aromatic compounds through an AlCl3-induced C-H activation process provides azoimidazolium dyes in good yields. PMID:25420599

  3. A case report on the anxiolytic properties of nitrous oxide during labor.

    PubMed

    Collins, Michelle

    2015-01-01

    Widely used in Europe as a labor analgesic, nitrous oxide (N2O) is making a dramatic return in the United States. Valued for its analgesic properties, N2O also has anxiolytic characteristics. Fear and anxiety in childbirth have been associated with various negative effects, and N2O may have the potential to lessen these effects for some women. Women in the United States should have the option of using N2O during labor.

  4. Coupling of nitrous oxide and methane by global atmospheric chemistry.

    PubMed

    Prather, Michael J; Hsu, Juno

    2010-11-12

    Nitrous oxide (N(2)O) and methane (CH(4)) are chemically reactive greenhouse gases with well-documented atmospheric concentration increases that are attributable to anthropogenic activities. We quantified the link between N(2)O and CH(4) emissions through the coupled chemistries of the stratosphere and troposphere. Specifically, we simulated the coupled perturbations of increased N(2)O abundance, leading to stratospheric ozone (O(3)) depletion, altered solar ultraviolet radiation, altered stratosphere-to-troposphere O(3) flux, increased tropospheric hydroxyl radical concentration, and finally lower concentrations of CH(4). The ratio of CH(4) per N(2)O change, -36% by mole fraction, offsets a fraction of the greenhouse effect attributable to N(2)O emissions. These CH(4) decreases are tied to the 108-year chemical mode of N(2)O, which is nine times longer than the residence time of direct CH(4) emissions.

  5. 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.

  6. Nitrous oxide fluxes in estuarine environments: response to global change.

    PubMed

    Murray, Rachel H; Erler, Dirk V; Eyre, Bradley D

    2015-09-01

    Nitrous oxide is a powerful, long-lived greenhouse gas, but we know little about the role of estuarine areas in the global N2 O budget. This review summarizes 56 studies of N2 O fluxes and associated biogeochemical controlling factors in estuarine open waters, salt marshes, mangroves, and intertidal sediments. The majority of in situ N2 O production occurs as a result of sediment denitrification, although the water column contributes N2 O through nitrification in suspended particles. The most important factors controlling N2 O fluxes seem to be dissolved inorganic nitrogen (DIN) and oxygen availability, which in turn are affected by tidal cycles, groundwater inputs, and macrophyte density. The heterogeneity of coastal environments leads to a high variability in observations, but on average estuarine open water, intertidal and vegetated environments are sites of a small positive N2 O flux to the atmosphere (range 0.15-0.91; median 0.31; Tg N2 O-N yr(-1) ). Global changes in macrophyte distribution and anthropogenic nitrogen loading are expected to increase N2 O emissions from estuaries. We estimate that a doubling of current median NO3 (-) concentrations would increase the global estuary water-air N2 O flux by about 0.45 Tg N2 O-N yr(-1) or about 190%. A loss of 50% of mangrove habitat, being converted to unvegetated intertidal area, would result in a net decrease in N2 O emissions of 0.002 Tg N2 O-N yr(-1) . In contrast, conversion of 50% of salt marsh to unvegetated area would result in a net increase of 0.001 Tg N2 O-N yr(-1) . Decreased oxygen concentrations may inhibit production of N2 O by nitrification; however, sediment denitrification and the associated ratio of N2 O:N2 is expected to increase. PMID:25752934

  7. Synthesis of triazenes with nitrous oxide.

    PubMed

    Kiefer, Gregor; Riedel, Tina; Dyson, Paul J; Scopelliti, Rosario; Severin, Kay

    2015-01-01

    Triazenes are valuable compounds in organic chemistry and numerous applications have been reported. Furthermore, triazenes have been investigated extensively as potential antitumor drugs. Here, we describe a new method for the synthesis of triazenes. The procedure involves a reagent which is rarely used in synthetic organic chemistry: nitrous oxide (N2 O, "laughing gas"). Nitrous oxide mediates the coupling of lithium amides and organomagnesium compounds while serving as a nitrogen donor. Despite the very inert character of nitrous oxide, the reactions can be performed in solution under mild conditions. A key advantage of the new procedure is the ability to access triazenes with alkynyl and alkenyl substituents. These compounds are difficult to prepare by conventional methods because the required starting materials are unstable. Some of the new alkynyltriazenes were found to display high cytotoxicity in in vitro tests on ovarian and breast cancer cell lines. PMID:25336431

  8. 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.

  9. 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. PMID:26718748

  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. Benzene/nitrous oxide flammability in the precipitate hydrolysis process

    SciTech Connect

    Jacobs, R A

    1989-09-18

    The HAN (hydroxylamine nitrate) process for destruction of nitrite in precipitate hydrolysis produces nitrous oxide (N2O) gas as one of the products. N2O can form flammable mixtures with benzene which is also present due to radiolysis and hydrolysis of tetraphenylborate. Extensive flame modeling and explosion testing was undertaken to define the minimum oxidant for combustion of N2O/benzene using both nitrogen and carbon dioxide as diluents. The attached memorandum interprets and documents the results of the studies.

  12. 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...

  13. 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...

  14. Abiotic Nitrous Oxide Production in Natural and Artificial Seawater

    NASA Astrophysics Data System (ADS)

    Ochoa, H.; Stanton, C. L.; Cavazos, A. R.; Ostrom, N. E.; Glass, J. B.

    2014-12-01

    The ocean contributes approximately one third of global sources of nitrous oxide (N2O) to the atmosphere. While nitrification is thought to be the dominant pathway for marine N2O production, mechanisms remain unresolved. Previous studies have carried the implicit assumption that marine N2O originates directly from enzymatic sources. However, abiotic production of N2O is possible via chemical reactions between nitrogenous intermediates and redox active trace metals in seawater. In this study, we investigated N2O production and isotopic composition in treatments with and without added hydroxylamine (NH2OH) and nitric oxide (NO), intermediates in microbial oxidation of ammonia to nitrite, and Fe(III). Addition of substrates to sterile artificial seawater was compared with filtered and unfiltered seawater from Sapelo Island, coastal Georgia, USA. N2O production was observed immediately after addition of Fe(III) in the presence of NH2OH at pH 8 in sterile artificial seawater. Highest N2O production was observed in the presence of Fe(III), NO, and NH2OH. The isotopomer site preference of abiotically produced N2O was consistent with previous studies (31 ± 2 ‰). Higher abiotic N2O production was observed in sterile artificial seawater (salinity: 35 ppt) than filtered Sapelo Island seawater (salinity: 25 ppt) whereas diluted sterile artificial seawater (18 ppt) showed lowest N2O production, suggesting that higher salinity promotes enhanced abiotic N2O production. Addition of Fe(III) to unfiltered Sapelo Island seawater stimulated N2O production. The presence of ammonia-oxidizing archaea (AOA), which lack known N2O producing enzymes, in Sapelo Island seawater was confirmed by successful amplification of the archaeal amoA gene, whereas ammonia-oxidizing bacteria (AOB), which contain N2O-producing enzymes were undetected. Given the few Fe-containing proteins present in AOA, it is likely that Fe(III) addition promoted N2O production via an abiotic vs. enzymatic N2O mechanism

  15. Production of oceanic nitrous oxide by ammonia-oxidizing archaea

    NASA Astrophysics Data System (ADS)

    Löscher, C. R.; Kock, A.; Könneke, M.; LaRoche, J.; Bange, H. W.; Schmitz, R. A.

    2012-07-01

    The recent finding that microbial ammonia oxidation in the ocean is performed by archaea to a greater extent than by bacteria has drastically changed the view on oceanic nitrification. The numerical dominance of archaeal ammonia-oxidizers (AOA) over their bacterial counterparts (AOB) in large parts of the ocean leads to the hypothesis that AOA rather than AOB could be the key organisms for the oceanic production of the strong greenhouse gas nitrous oxide (N2O) that occurs as a by-product of nitrification. Very recently, enrichment cultures of marine ammonia-oxidizing archaea have been reported to produce N2O. Here, we demonstrate that archaeal ammonia monooxygenase genes (amoA) were detectable throughout the water column of the eastern tropical North Atlantic (ETNA) and eastern tropical South Pacific (ETSP) Oceans. Particularly in the ETNA, comparable patterns of abundance and expression of archaeal amoA genes and N2O co-occurred in the oxygen minimum, whereas the abundances of bacterial amoA genes were negligible. Moreover, selective inhibition of archaea in seawater incubations from the ETNA decreased the N2O production significantly. In studies with the only cultivated marine archaeal ammonia-oxidizer Nitrosopumilus maritimus SCM1, we provide the first direct evidence for N2O production in a pure culture of AOA, excluding the involvement of other microorganisms as possibly present in enrichments. N. maritimus showed high N2O production rates under low oxygen concentrations comparable to concentrations existing in the oxycline of the ETNA, whereas the N2O production from two AOB cultures was comparably low under similar conditions. Based on our findings, we hypothesize that the production of N2O in tropical ocean areas results mainly from archaeal nitrification and will be affected by the predicted decrease in dissolved oxygen in the ocean.

  16. Production of oceanic nitrous oxide by ammonia-oxidizing archaea

    NASA Astrophysics Data System (ADS)

    Loescher, C. R.; Kock, A.; Koenneke, M.; Laroche, J.; Bange, H. W.; Schmitz, R. A.

    2012-02-01

    The recent finding that microbial ammonia oxidation in the ocean is performed by archaea to a greater extent than by bacteria has drastically changed the view on oceanic nitrification. The numerical dominance of archaeal ammonia-oxidizers (AOA) over their bacterial counterparts (AOB) in large parts of the ocean leads to the hypothesis that AOA rather than AOB could be the key organisms for the oceanic production of the strong greenhouse gas nitrous oxide (N2O) which occurs as a by-product of nitrification. Very recently, enrichment cultures of marine ammonia-oxidizing archaea have been described to produce N2O. Here, we demonstrate that archaeal ammonia monooxygenase genes (amoA) were detectable throughout the water column of the Eastern Tropical North Atlantic (ETNA) and Eastern Tropical South Pacific Oceans (ETSP). Particularly in the ETNA, maxima in abundance and expression of archaeal amoA genes correlated with the N2O maximum and the oxygen minimum, whereas the abundances of bacterial amoA genes were negligible. Moreover, selective inhibition of archaea in seawater incubations from the ETNA decreased the N2O production significantly. In studies with the only cultivated marine archaeal ammonia-oxidizer Nitrosopumilus maritimus SCM1, we provide the first direct evidence for N2O production in a pure culture of AOA, excluding the involvement of other microorganisms as possibly present in enrichments. N. maritimus showed high N2O production rates under low oxygen concentrations comparable to concentrations existing in the oxycline of the ETNA, whereas the N2O production from two AOB cultures was comparably low under similar conditions. Based on our findings, we hypothesize that the production of N2O in tropical ocean areas results mainly from archaeal nitrification and will be affected by the predicted decrease in dissolved oxygen in the ocean.

  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. Production of nitrous oxide in the auroral D and E regions

    NASA Technical Reports Server (NTRS)

    Zipf, E. C.; Prasad, S. S.

    1980-01-01

    A study of nitrous oxide formation mechanisms indicates that N2O concentrations greater than 10 to the 9th per cu cm could be produced in IBC III aurora or by lower-level activity lasting for many hours, and, in favorable conditions, the N2O concentration could exceed the local nitric oxide density. An upper limit on the globally averaged N2O production rate from auroral activity is estimated at 2 x 10 to the 27th per second.

  19. 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.

  20. Nitrogen cycling. Rapid nitrous oxide cycling in the suboxic ocean.

    PubMed

    Babbin, Andrew R; Bianchi, Daniele; Jayakumar, Amal; Ward, Bess B

    2015-06-01

    Nitrous oxide (N2O) is a powerful greenhouse gas and a major cause of stratospheric ozone depletion, yet its sources and sinks remain poorly quantified in the oceans. We used isotope tracers to directly measure N2O reduction rates in the eastern tropical North Pacific. Because of incomplete denitrification, N2O cycling rates are an order of magnitude higher than predicted by current models in suboxic regions, and the spatial distribution suggests strong dependence on both organic carbon and dissolved oxygen concentrations. Furthermore, N2O turnover is 20 times higher than the net atmospheric efflux. The rapid rate of this cycling coupled to an expected expansion of suboxic ocean waters implies future increases in N2O emissions. PMID:26045434

  1. Rapid nitrous oxide cycling in the suboxic ocean

    NASA Astrophysics Data System (ADS)

    Babbin, Andrew R.; Bianchi, Daniele; Jayakumar, Amal; Ward, Bess B.

    2015-06-01

    Nitrous oxide (N2O) is a powerful greenhouse gas and a major cause of stratospheric ozone depletion, yet its sources and sinks remain poorly quantified in the oceans. We used isotope tracers to directly measure N2O reduction rates in the eastern tropical North Pacific. Because of incomplete denitrification, N2O cycling rates are an order of magnitude higher than predicted by current models in suboxic regions, and the spatial distribution suggests strong dependence on both organic carbon and dissolved oxygen concentrations. Furthermore, N2O turnover is 20 times higher than the net atmospheric efflux. The rapid rate of this cycling coupled to an expected expansion of suboxic ocean waters implies future increases in N2O emissions.

  2. Structure and Abundance of Nitrous Oxide Complexes in Earth's Atmosphere.

    PubMed

    Salmon, Steven R; de Lange, Katrina M; Lane, Joseph R

    2016-04-01

    We have investigated the lowest energy structures and binding energies of a series of atmospherically relevant nitrous oxide (N2O) complexes using explicitly correlated coupled cluster theory. Specifically, we have considered complexes with nitrogen (N2-N2O), oxygen (O2-N2O), argon (Ar-N2O), and water (H2O-N2O). We have calculated rotational constants and harmonic vibrational frequencies for the complexes and the constituent monomers. Statistical mechanics was used to determine the thermodynamic parameters for complex formation as a function of temperature and pressure. These results, in combination with relevant atmospheric data, were used to estimate the abundance of N2O complexes in Earth's atmosphere as a function of altitude. We find that the abundance of N2O complexes in Earth's atmosphere is small but non-negligible, and we suggest that N2O complexes may contribute to absorption of terrestrial radiation and be relevant for understanding the atmospheric fate of N2O.

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

    PubMed

    Corona, Teresa; Company, Anna

    2016-10-01

    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. PMID:27445004

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

    PubMed

    Corona, Teresa; Company, Anna

    2016-10-01

    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.

  5. 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. PMID:26912510

  6. 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...

  7. Estimating ammonia and nitrous oxide emissions from dairy farms using milk urea nitrogen

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dairy farms emit ammonia (NH3) from barns, manure storage, and soils, which can be hazardous to human and ecosystem health. Emissions of NH3 also contribute indirectly to emissions of nitrous oxide (N2O), a potent greenhouse gas. Direct N2O emissions occur mostly from soil after application of ferti...

  8. 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 ...

  9. 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...

  10. 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...

  11. 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 ...

  12. 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...

  13. 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...

  14. Challenges and opportunities for mitigating nitrous oxide emissions from fertilized cropping systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) represents in many cases the largest single component of the greenhouse gas (GHG) budget of individual cropping systems and for the U.S. agricultural sector as a whole. Reducing N2O emissions from cropping systems remains a research frontier largely because of biophysical factors...

  15. 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...

  16. 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 ...

  17. 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 ...

  18. 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...

  19. Improved measurements of atmospheric nitrous oxide

    NASA Astrophysics Data System (ADS)

    Wendel, JoAnna

    2014-10-01

    Nitrous oxide (N2O), one of the main greenhouse gases, is known for its degrading effect on Earth's ozone layer. The gas is created naturally by microbial activity on land and in the oceans and artificially by emissions from human-made processes, through fertilization or burning fossil fuels. As the climate continues to warm, it has become imperative to be able to track and quantify the greenhouse gas content of the atmosphere, and various satellite missions have been launched to do so.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

    Reed, S.; Uriarte, M.; Wood, T. E.; Cavaleri, M. A.; Lugo, A. E.

    2014-12-01

    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.

  2. 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.

  3. The reduction of nitrous oxide to dinitrogen by Escherichia coli.

    PubMed

    Kaldorf, M; Linne von Berg, K H; Meier, U; Servos, U; Bothe, H

    1993-01-01

    Escherichia coli K12 reduces nitrous oxide stoichiometrically to molecular nitrogen with rates of 1.9 mumol/h x mg protein. The activity is induced by anaerobiosis and nitrate. N2-formation from N2O is inhibited by C2H2 (Ki approximately 0.03 mM in the medium) and nitrite (Ki = 0.3 mM) but not by azide. A mutant defective in FNR synthesis is unable to reduce N2O to N2. The reaction in the wild type could routinely be followed by gas chromatography and alternatively by mass spectrometry measuring the formation of 15N2 from 15N2O. The enzyme catalyzing N2O-reduction in E. coli could not be identified; it is probably neither nitrate reductase nor nitrogenase. E. coli does not grow with N2O as sole respiratory electron acceptor. N2O-reduction might not have a physiological role in E. coli, and the enzyme involved might catalyze something else in nature, as it has a low affinity for the substrate N2O (apparent Km approximately 3.0 mM). The capability for N2O-reduction to N2 is not restricted to E. coli but is also demonstrable in Yersinia kristensenii and Buttiauxella agrestis of the Enterobacteriaceae. E. coli is able to produce NO and N2O from nitrite by nitrate reductase, depending on the assay conditions. In such experiments NO2- is not reduced to N2 because of the high demand for N2O of N2O-reduction and the inhibitory effect of NO2- on this reaction.

  4. 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.

  5. Seasonal variability in emission of nitrous oxide from soil

    NASA Astrophysics Data System (ADS)

    Bremner, J. M.; Robbins, S. G.; Blackmer, A. M.

    1980-09-01

    Seasonal variability in emission of nitrous oxide (N2O) from soil was studied by monitoring N2O emissions from six Iowa soils for 12 months (mid-April, 1979 to mid-April, 1980). The soils studied were representative of soils used extensively for corn and soybean production in north-central Iowa. They had been planted to soybeans and had received no N fertilization. The amounts of N2O-N evolved from these soils in 12 months ranged from 0.34 to 1.97 kg ha-1 and averaged 1.20 kg ha-1. A substantial proportion (average, 67%) of the N2O evolved in 12 months was produced during the summer months of the study period, whereas only a small proportion (average, 2%) was produced during the winter months. The corresponding proportions for the spring and fall months were 18% and 13%, respectively.

  6. Catalytic decomposition of N2O on ordered crystalline metal oxides.

    PubMed

    Ma, Zhen; Ren, Yu; Lu, Yanbin; Bruce, Peter G

    2013-07-01

    The synthesis of mesoporous metal oxides using mesoporous silicas or carbons as hard templates has attracted growing interest recently, but the catalytic application of mesoporous metal oxides has not been studied sufficiently. In addition, few publications have compared the catalytic performance of a series of mesoporous metal oxides in the same reaction, and little is known about the influence of preparation details of mesoporous metal oxides on catalytic activity. Herein, ordered crystalline mesoporous metal oxides (i.e., CeO2, Co3O4, Cr2O3, CuO, alpha-Fe2O3, beta-MnO2, Mn2O3, Mn3O4, NiO) prepared using mesoporous SiO2 (KIT-6) as a hard template were tested in the decomposition of N2O, an environmental pollutant, and the catalytic performance was compared with that of commercial metal oxides with low surface areas. In particular, mesoporous Co3O4, beta-MnO2, and NiO showed high N2O conversions at 350 degrees C. The influence of preparation parameters of mesoporous Co3O4 on catalytic activity was then studied in more detail. Mesoporous Co3O4 samples with different pore sizes and wall thicknesses were prepared using KIT-6 synthesized under different hydrothermal or calcination temperatures. Interestingly, the catalytic activities of different mesoporous Co3O4 samples were found to be influenced by these preparation details. PMID:23901535

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

    PubMed Central

    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. PMID:1809046

  8. Nitrous oxide production from sequencing batch reactor sludge under nitrifying conditions: effect of nitrite concentrations.

    PubMed

    Gong, Youkui; Wang, Shuying; Wang, Sai; Peng, Yongzhen

    2012-01-01

    Nitrous oxide (N2O), a greenhouse gas which contributes to the destruction of the stratospheric ozone layer, can be emitted from nitrifying processes during wastewater treatment. The pathway of N2O production was studied using a lab-scale nitrifying reactor. Allylthiourea was used to inhibit NH4+ oxidation and provide information on processes that happen under nitrifying condition. Our study confirmed that besides heterotrophic bacteria, ammonium-oxidizing bacteria could perform denitrification processes, during which NO2- was the electron acceptor and NH4+ was the electron donor, with N2 and N2O as final products. The relative contribution of the heterotrophic denitrification process to total N2O emissions varied from 46.1% to 60.4% depending on NO2(-)-N addition. Correspondingly, 21.8% to 51.5% of total N2O emissions can be attributed to nitrifier denitrification. Little N2O is emitted during the NO2- oxidation process.

  9. Nitrous oxide flux from landfill leachate-sawdust nitrogenous compost.

    PubMed

    Hui, C H; So, M K; Lee, C M; Chan, G Y S

    2003-09-01

    Composted nitrogenous waste has the potential to produce excessive amounts of nitrous oxide (N2O), a potent greenhouse gas that also contributes to stratospheric ozone depletion. In this laboratory study, sawdust was irrigated with varying amounts of landfill leachate with high NH4+-N content (3950 mg l(-1)). Physicochemical properties, including the amount of N2O produced, were monitored during the composting process over 28 days. A rapid decline in NH4+-N in the first 4 days and increasing NO3--N for 11 days was followed by lower but stabilized levels of available-N, even with repeated leachate irrigation. Less than 0.03% of the leachate-applied N was lost as N2O. Higher leachate applications as much as tripled N2O production, but this represented a lesser proportion overall of the total nitrogen. Addition of glucose to the composting process had no significant effect on N2O production. The derived sawdust-leachate compost supported healthy growth of Sesbania rostrata. It is concluded that compost can be produced from sawdust irrigated with landfill leachate without substantial emission of N2O, although excessive flux of N2O remains about high application rates over longer time periods. PMID:12867187

  10. Macro- and microvascular effects of nitrous oxide in the rat.

    PubMed Central

    Matheny, J. L.; Westphal, K. A.; Richardson, D. R.; Roth, G. I.

    1991-01-01

    The aims of this study were: (1) to determine the macro- and microvascular actions of nitrous oxide (N2O) in the rat, and (2) to determine whether the vascular actions of N2O involved specific interaction with alpha-adrenergic receptors or opioid receptors. Systolic blood pressure, heart rat, total tail blood flow, blood cell velocity in subepidermal capillaries of the tail, and percentage of capillaries exhibiting flow were monitored in conscious rats during the administration of N2O before and after administration of clonidine (an alpha 2-adrenergic agonist), prazosin (an alpha 1-adrenergic antagonist) or naloxone (an opioid antagonist). Total tail blood flow increased significantly in a dose-dependent manner with N2O at 20% and 40% with oxygen. This action of N2O was not blocked by clonidine, prazosin, or naloxone. Capillary flow velocity increased during 20% and 40% N2O compared to 100% O2, but the changes were not statistically significant nor did they correlate with the changes in tail blood flow. These data suggest that the peripheral vascular action of N2O does not involve specific actions at alpha-adrenergic receptors or opioid receptors and may be the result of direct actions on the peripheral vasculature. PMID:1667350

  11. 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.

  12. 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. PMID:26152454

  13. Nitrous oxide and occupational exposure: it's time to stop laughing.

    PubMed

    Kugel, G; Norris, L H; Zive, M A

    1989-01-01

    Although nitrous oxide (N(2)O) has been widely used since 1844, in recent years it has been implicated in a number of serious health hazards such as reproductive, nerve, liver, and kidney disorders. The National Institute of Safety and Health (NIOSH) recommends a limit of 25 ppm for chronic exposure to N(2)O in the dental office. Our study monitored ambient N(2)O levels in the dental office. N(2)O levels were compared for procedures performed in open clinics and private operatories as well as with and without a gas-scavenging system. Measurements were taken in the Dental Breathing Zone (DBZ) and Dental Chair Foot (DCF) at regular intervals. A four- to eightfold increase in average N(2)O levels was noted in the DBZ for unscavenged versus scavenged procedures. A three- to fourfold increase for unscavenged versus scavenged procedures was similarly noted in the DCF. N(2)O were significantly higher in private operatories than in open clinics, due to limited room volumes and in the DBZ over the DCF, due to mask leakage and increased oral exhalation. Scavenged N(2)O levels for both operatory types did not meet NIOSH guidelines. In contrast to previous studies using any form of gas removal, our study shows a significant decrease in N(2)O level achieved with an adequate scavenger system. With only four states regulating the use of N(2)O, and with concern over its deleterious effects growing, additional states and the federal government are expected to enact legislation regulating the use of N(2)O in the near future. PMID:2490056

  14. 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...

  15. 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...

  16. CO oxidation at nickel centres by N2O or O2 to yield a novel hexanuclear carbonate.

    PubMed

    Horn, Bettina; Limberg, Christian; Herwig, Christian; Feist, Michael; Mebs, Stefan

    2012-08-25

    Reaction of a nickel(0) carbonyl complex, K(2)[L(tBu)NiCO](2), with N(2)O generates a cyclic carbonate compound composed of six [Ni(II)(CO(3))K](+) units. The same product can also be obtained using O(2) as the oxidant in a solid-state/gas reaction. These conversions represent unique examples of a nickel-bound CO oxidation by N(2)O and O(2), respectively. PMID:22785444

  17. Nitrous oxide emissions in the Shanghai river network: implications for the effects of urban sewage and IPCC methodology.

    PubMed

    Yu, Zhongjie; Deng, Huanguang; Wang, Dongqi; Ye, Mingwu; Tan, Yongjie; Li, Yangjie; Chen, Zhenlou; Xu, Shiyuan

    2013-10-01

    Global nitrogen (N) enrichment has resulted in increased nitrous oxide (N(2)O) emission that greatly contributes to climate change and stratospheric ozone destruction, but little is known about the N(2)O emissions from urban river networks receiving anthropogenic N inputs. We examined N(2)O saturation and emission in the Shanghai city river network, covering 6300 km(2), over 27 months. The overall mean saturation and emission from 87 locations was 770% and 1.91 mg N(2)O-N m(-2) d(-1), respectively. Nitrous oxide (N(2)O) saturation did not exhibit a clear seasonality, but the temporal pattern was co-regulated by both water temperature and N loadings. Rivers draining through urban and suburban areas receiving more sewage N inputs had higher N(2)O saturation and emission than those in rural areas. Regression analysis indicated that water ammonium (NH(4)(+)) and dissolved oxygen (DO) level had great control on N(2)O production and were better predictors of N(2)O emission in urban watershed. About 0.29 Gg N(2)O-N yr(-1) N(2)O was emitted from the Shanghai river network annually, which was about 131% of IPCC's prediction using default emission values. Given the rapid progress of global urbanization, more study efforts, particularly on nitrification and its N(2)O yielding, are needed to better quantify the role of urban rivers in global riverine N(2)O emission.

  18. Analgesic and physiological effects in conscious sedation with different nitrous oxide concentrations

    PubMed Central

    Bonafé-Monzó, Neus; Rojo-Moreno, Juan

    2015-01-01

    Objectives: to study the physiological changes, as well as the psychosedative and analgesic effects of nitrous oxide, in experimental conditions. Study Design: 101 dental students volunteers participated in a single nitrous oxide sedation session without dental treatment. Signs and symptoms were registered during and after the procedure. Pulse rate and hemoglobin oxygen saturation were monitored at: 100 per cent O2, 30 per cent N2O, 50 per cent N2O and 5 minutes after 100 per cent O2. A Likert scale was used to evaluate pain perception. The analgesic effects of nitrous oxide were evaluated at: 30 per cent N2O, 50 per cent N2O, and five minutes postoperatively. Results: Pulse rate and hemoglobin oxygen saturation decreased significantly through all the procedure and after recovery. However, oxygen saturation recovered after the final oxygenation. Only 8.2% of subjects reported the pain stimulus as being quite annoying when they inhaled 30 per cent N2O, while this percentage was of 15.8 % when inhaling 50 per cent N2O, and of 32.7 % during the recovery period. The most common effects of nitrous oxide sedation were bright eyes (99%), voice change (98%) and smiling (91%). Most of the subjects reported tingling (98%) and relax (91.1%) Conclusions: nitrous oxide causes a significant decrease in heart rate and oxygen saturation, but always within safety limits. Maintaining an appropriate level of consciousness was confirmed as a feature in 50 per cent dose in this study. The analgesic effect of nitrous oxide was confirmed but a dose dependency could not be established. Key words:Nitrous oxide, conscious sedation, anxiolysis, safety, physiogical parameters, signs, symptoms, analgesia. PMID:25810844

  19. Evaluation of Nitrous Oxide Emission from Sulfide- and Sulfur-Based Autotrophic Denitrification Processes.

    PubMed

    Liu, Yiwen; Peng, Lai; Ngo, Huu Hao; Guo, Wenshan; Wang, Dongbo; Pan, Yuting; Sun, Jing; Ni, Bing-Jie

    2016-09-01

    Recent studies have shown that sulfide- and sulfur-based autotrophic denitrification (AD) processes play an important role in contributing to nitrous oxide (N2O) production and emissions. However, N2O production is not recognized in the current AD models, limiting their ability to predict N2O accumulation during AD. In this work, a mathematical model is developed to describe N2O dynamics during sulfide- and sulfur-based AD processes for the first time. The model is successfully calibrated and validated using N2O data from two independent experimental systems with sulfide or sulfur as electron donors for AD. The model satisfactorily describes nitrogen reductions, sulfide/sulfur oxidation, and N2O accumulation in both systems. Modeling results revealed substantial N2O accumulation due to the relatively low N2O reduction rate during both sulfide- and sulfur-based AD processes. Application of the model to simulate long-term operations of activated sludge systems performing sulfide- and sulfur-based AD processes indicates longer sludge retention time reduced N2O emission. For sulfide-based AD process, higher initial S/N ratio also decreased N2O emission but with a higher operational cost. This model can be a useful tool to support process operation optimization for N2O mitigation during AD with sulfide or sulfur as electron donor. PMID:27501384

  20. 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

  1. Strategies to mitigate nitrous oxide emissions from herbivore production systems.

    PubMed

    Schils, R L M; Eriksen, J; Ledgard, S F; Vellinga, Th V; Kuikman, P J; Luo, J; Petersen, S O; Velthof, G L

    2013-03-01

    Herbivores are a significant source of nitrous oxide (N(2)O) emissions. They account for a large share of manure-related N(2)O emissions, as well as soil-related N(2)O emissions through the use of grazing land, and land for feed and forage production. It is widely acknowledged that mitigation measures are necessary to avoid an increase in N(2)O emissions while meeting the growing global food demand. The production and emissions of N(2)O are closely linked to the efficiency of nitrogen (N) transfer between the major components of a livestock system, that is, animal, manure, soil and crop. Therefore, mitigation options in this paper have been structured along these N pathways. Mitigation technologies involving diet-based intervention include lowering the CP content or increasing the condensed tannin content of the diet. Animal-related mitigation options also include breeding for improved N conversion and high animal productivity. The main soil-based mitigation measures include efficient use of fertilizer and manure, including the use of nitrification inhibitors. In pasture-based systems with animal housing facilities, reducing grazing time is an effective option to reduce N(2)O losses. Crop-based options comprise breeding efforts for increased N-use efficiency and the use of pastures with N(2)-fixing clover. It is important to recognize that all N(2)O mitigation options affect the N and carbon cycles of livestock systems. Therefore, care should be taken that reductions in N(2)O emissions are not offset by unwanted increases in ammonia, methane or carbon dioxide emissions. Despite the abundant availability of mitigation options, implementation in practice is still lagging. Actual implementation will only follow after increased awareness among farmers and greenhouse gases targeted policies. So far, reductions in N(2)O emissions that have been achieved are mostly a positive side effect of other N-targeted policies.

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

    PubMed

    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 × 10(8) 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.

  3. 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

  4. Strategies to mitigate nitrous oxide emissions from herbivore production systems.

    PubMed

    Schils, R L M; Eriksen, J; Ledgard, S F; Vellinga, Th V; Kuikman, P J; Luo, J; Petersen, S O; Velthof, G L

    2013-03-01

    Herbivores are a significant source of nitrous oxide (N(2)O) emissions. They account for a large share of manure-related N(2)O emissions, as well as soil-related N(2)O emissions through the use of grazing land, and land for feed and forage production. It is widely acknowledged that mitigation measures are necessary to avoid an increase in N(2)O emissions while meeting the growing global food demand. The production and emissions of N(2)O are closely linked to the efficiency of nitrogen (N) transfer between the major components of a livestock system, that is, animal, manure, soil and crop. Therefore, mitigation options in this paper have been structured along these N pathways. Mitigation technologies involving diet-based intervention include lowering the CP content or increasing the condensed tannin content of the diet. Animal-related mitigation options also include breeding for improved N conversion and high animal productivity. The main soil-based mitigation measures include efficient use of fertilizer and manure, including the use of nitrification inhibitors. In pasture-based systems with animal housing facilities, reducing grazing time is an effective option to reduce N(2)O losses. Crop-based options comprise breeding efforts for increased N-use efficiency and the use of pastures with N(2)-fixing clover. It is important to recognize that all N(2)O mitigation options affect the N and carbon cycles of livestock systems. Therefore, care should be taken that reductions in N(2)O emissions are not offset by unwanted increases in ammonia, methane or carbon dioxide emissions. Despite the abundant availability of mitigation options, implementation in practice is still lagging. Actual implementation will only follow after increased awareness among farmers and greenhouse gases targeted policies. So far, reductions in N(2)O emissions that have been achieved are mostly a positive side effect of other N-targeted policies. PMID:23031718

  5. 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

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

    PubMed

    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 × 10(8) 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

  7. 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.

  8. 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

  9. N2O molecular tagging velocimetry

    NASA Astrophysics Data System (ADS)

    ElBaz, A. M.; Pitz, R. W.

    2012-03-01

    A new seeded velocity measurement technique, N2O molecular tagging velocimetry (MTV), is developed to measure velocity in wind tunnels by photochemically creating an NO tag line. Nitrous oxide "laughing gas" is seeded into the air flow. A 193 nm ArF excimer laser dissociates the N2O to O(1D) that subsequently reacts with N2O to form NO. O2 fluorescence induced by the ArF laser "writes" the original position of the NO line. After a time delay, the shifted NO line is "read" by a 226-nm laser sheet and the velocity is determined by time-of-flight. At standard atmospheric conditions with 4% N2O in air, ˜1000 ppm of NO is photochemically created in an air jet based on experiment and simulation. Chemical kinetic simulations predict 800-1200 ppm of NO for 190-750 K at 1 atm and 850-1000 ppm of NO for 0.25-1 atm at 190 K. Decreasing the gas pressure (or increasing the temperature) increases the NO ppm level. The presence of humid air has no significant effect on NO formation. The very short NO formation time (<10 ns) makes the N2O MTV method amenable to low- and high-speed air flow measurements. The N2O MTV technique is demonstrated in air jet to measure its velocity profile. The N2O MTV method should work in other gas flows as well (e.g., helium) since the NO tag line is created by chemical reaction of N2O with O(1D) from N2O photodissociation and thus does not depend on the bulk gas composition.

  10. Effect of urea application rate and water content on nitrous oxide emission from a sandy loam soil - a laboratory study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agriculture is a major contributor to global anthropogenic nitrous oxide (N2O, a potent greenhouse gas) emission. Data from a pomegranate orchard indicate that N2O emission is highly variable with nitrogen application rates and irrigation methods. The aim of this study was to investigate the effect ...

  11. 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...

  12. 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...

  13. 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

  14. Clumped isotope perturbation in tropospheric nitrous oxide from stratospheric photolysis

    NASA Astrophysics Data System (ADS)

    Schmidt, Johan A.; Johnson, Matthew S.

    2015-05-01

    Nitrous oxide (N2O) is potent greenhouse gas and source of ozone depleting NO to the stratosphere. Recent advances in mass spectrometry allow accurate measurement of multiply substituted ("clumped") N2O isotopocules, providing new constraints on the N2O source budget. However, this requires a quantification of the "clumped" N2O fractionation from stratospheric photolysis (main sink). We use time-dependent quantum dynamics and a 1-D atmospheric model to determine the effect of stratospheric photolysis on the abundances of multisubstituted N2O isotopocules in the atmosphere. The ultraviolet absorption cross sections of 557 (i.e., 15N15N17O), 458, 548, 457, and 547 are presented for the first time and used to derive altitude-dependent photolysis rates and fractionation constants. We find that photolysis alters the N2O isotopic composition with multisubstituted mass 47 isotopocules being less abundant than expected from stochastics (Δ47 = -1.7‰ in the troposphere and down to -12‰ in the upper stratosphere).

  15. Soil formate regulates the fungal nitrous oxide emission pathway.

    PubMed

    Ma, W K; Farrell, R E; Siciliano, S D

    2008-11-01

    Fungal activity is a major driver in the global nitrogen cycle, and mounting evidence suggests that fungal denitrification activity contributes significantly to soil emissions of the greenhouse gas nitrous oxide (N(2)O). The metabolic pathway and oxygen requirement for fungal denitrification are different from those for bacterial denitrification. We hypothesized that the soil N(2)O emission from fungi is formate and O(2) dependent and that land use and landforms could influence the proportion of N(2)O coming from fungi. Using substrate-induced respiration inhibition under anaerobic and aerobic conditions in combination with (15)N gas analysis, we found that formate and hypoxia (versus anaerobiosis) were essential for the fungal reduction of (15)N-labeled nitrate to (15)N(2)O. As much as 65% of soil-emitted N(2)O was attributable to fungi; however, this was found only in soils from water-accumulating landforms. From these results, we hypothesize that plant root exudates could affect N(2)O production from fungi via the proposed formate-dependent pathway. PMID:18791019

  16. 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.

  17. 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.

  18. Nitrous oxide in the atmosphere: First measurements of a lower thermospheric source

    NASA Astrophysics Data System (ADS)

    Sheese, Patrick E.; Walker, Kaley A.; Boone, Chris D.; Bernath, Peter F.; Funke, Bernd

    2016-03-01

    Nitrous oxide (N2O) is an important anthropogenic greenhouse gas, as well as one of the most significant anthropogenic ozone-depleting substances in the stratosphere. The satellite-based instrument Atmospheric Chemistry Experiment-Fourier Transform Spectrometer has been observing the Earth's limb since 2004 and derives profiles of N2O volume mixing ratios in the upper troposphere to the lower thermosphere. The resulting climatology shows that N2O is continuously produced in the lower thermosphere via energetic particle precipitation and enhanced N2O is present at all latitudes, during all seasons. The results are consistent with an N2O production source peaking near or above 94 km via low-energy particles, as well as a polar wintertime source near 70 km via medium energy particles. N2O produced in the polar upper atmosphere descends each winter to as far down as ~40 km.

  19. 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

  20. 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. PMID:23625707

  1. The Impact of Nutrient Inputs from Atmospheric and Riverine Sources on Oceanic Nitrous-oxide

    NASA Astrophysics Data System (ADS)

    Suntharalingam, Parvadha; Buitenhuis, Erik

    2014-05-01

    Nitrous-oxide (N2O) is a major greenhouse gas, and an important agent of stratospheric ozone depletion. Ocean emissions of nitrous-oxide account for over a quarter of present-day global natural N2O emissions to the atmosphere. This marine N2O source results from a combination of nitrification and denitrification reactions associated with the cycling of organic matter in the oxygenated and sub-oxic regions of the ocean. In addition, in intense sub-oxic and anoxic ocean zones, denitrification processes can provide a local sink of nitrous-oxide. It has been suggested that significant shifts in the global ocean-atmosphere N2O flux could result from changes in nutrient inputs to the ocean that stimulate marine productivity and hence influence N2O cycling and the net oceanic source to the atmosphere. In this analysis we employ the NEMO-PlankTOM10 global ocean biogeochemistry model, in conjunction with embedded representations of the ocean N2O cycle, to assess the relative influences, on present-day ocean N2O, of nutrient inputs to the ocean from atmospheric deposition and riverine fluxes. Specifically, we investigate nutrient forcing from contrasting sources including anthropogenic atmospheric deposition of NOy and NHx (Dentener et al 2006), atmospheric dust deposition (Jickells et al. 2005), and riverine inputs of Fe, Si, N, P, and organic and inorganic carbon (da Cunha et al. 2007). Model analyses are used to quantify the relative influences of these separate nutrient inputs on the net oceanic N2O source. We also characterize the uncertainty in our results associated with our modeled representation of N2O by evaluating the sensitivity to a set of empirically-based and process-based parameterizations of the marine N2O cycle.

  2. 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.

  3. Decomposition of nitrous oxide and chloromethanes absorbed on particulate matter

    NASA Technical Reports Server (NTRS)

    Rebbert, R. E.; Ausloos, P. J.

    1978-01-01

    The effect of pressure on the heterogeneous thermal and pyrolytic decomposition of nitrous oxides adsorbed on sand was studied. Results indicate that N20 adsorbed on certain sand surfaces can be decomposed by photons which nitrous oxide cannot absorb in the gas phase. There is also a thermal heterogeneous decomposition of nitrous oxide which also produces nitrogen. The photolysis of CC14, CFC13, CF2C12 adsorbed on fused quartz and on different types of sand was also investigated. There was no thermal heterogeneous reaction with any of these chloromethanes. Apparently the larger bond energy of approximately 74 kcal for the C-C1 bond compared to approximately 40 kcal for the N-O bond in N2O makes the thermal reaction inoperative for the chloromethanes.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Nitrous oxide fluxes from upland soils in central Hokkaido, Japan.

    PubMed

    Mu, Zhijian; Kimura, Sonoko D; Toma, Yo; Hatano, Ryusuke

    2008-01-01

    Nitrous oxide (N2O) fluxes from soils were measured using the closed chamber method during the snow-free seasons (middle April to early November), for three years, in a total of 11 upland crop fields in central Hokkaido, Japan. The annual mean N2O fluxes ranged from 2.95 to 164.17 microgN/(m2 x h), with the lowest observed in a grassland and the highest in an onion field. The instantaneous N2O fluxes showed a large temporal variation with peak emissions generally occurring following fertilization and heavy rainfall events around harvesting in autumn. No clear common factor regulating instantaneous N2O fluxes was found at any of the study sites. Instead, instantaneous N2O fluxes at different sites were affected by different soil variables. The cumulative N2O emissions during the study period within each year varied from 0.15 to 7.05 kgN/hm2 for different sites, which accounted for 0.33% to 5.09% of the applied fertilizer N. No obvious relationship was observed between cumulative N2O emission and applied fertilizer N rate (P > 0.4). However, the cumulative N2O emission was significantly correlated with gross mineralized N as estimated by CO2 emissions from bare soils divided by C/N ratios of each soil, and with soil mineral N pool (i.e., the sum of gross mineralized N and fertilizer N) (P < 0.001). PMID:19202870

  9. 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. PMID:27593286

  10. Interactions of N2O5 and related nitrogen oxides with ice surfaces: desorption kinetics and collision dynamics.

    PubMed

    Romero Lejonthun, Liza S E; Andersson, Patrik U; Hallquist, Mattias; Thomson, Erik S; Pettersson, Jan B C

    2014-11-26

    The detailed interactions of nitrogen oxides with ice are of fundamental interest and relevance for chemistry in cold regions of the atmosphere. Here, the interactions of NO, NO2, N2O4, and N2O5 with ice surfaces at temperatures between 93 and 180 K are investigated with molecular beam techniques. Surface collisions are observed to result in efficient transfer of kinetic energy and trapping of molecules on the ice surfaces. NO and NO2 rapidly desorb from pure ice with upper bounds for the surface binding energies of 0.16 ± 0.02 and 0.26 ± 0.03 eV, respectively. Above 150 K, N2O4 desorption follows first-order kinetics and is well described by the Arrhenius parameters Ea = 0.39 ± 0.04 eV and A = 10((15.4±1.2)) s(-1), while a stable N2O4 adlayer is formed at lower temperatures. A fraction of incoming N2O5 reacts to form HNO3 on the ice surface. The N2O5 desorption rates are substantially lower on pure water ice (Arrhenius parameters: Ea = 0.36 ± 0.02 eV; A = 10((15.3±0.7)) s(-1)) than on HNO3-covered ice (Ea = 0.24 ± 0.02 eV; A = 10((11.5±0.7)) s(-1)). The N2O5 desorption kinetics also sensitively depend on the sub-monolayer coverage of HNO3, with a minimum in N2O5 desorption rate at a low but finite coverage of HNO3. The studies show that none of the systems with resolvable desorption kinetics undergo ordinary desorption from ice, and instead desorption likely involves two or more surface states, with additional complexity added by coadsorbed molecules.

  11. 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...

  12. 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 ...

  13. 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. PMID:18808088

  14. 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

  15. Microbial regulation of terrestrial nitrous oxide formation: understanding the biological pathways for prediction of emission rates.

    PubMed

    Hu, Hang-Wei; Chen, Deli; He, Ji-Zheng

    2015-09-01

    The continuous increase of the greenhouse gas nitrous oxide (N2O) in the atmosphere due to increasing anthropogenic nitrogen input in agriculture has become a global concern. In recent years, identification of the microbial assemblages responsible for soil N2O production has substantially advanced with the development of molecular technologies and the discoveries of novel functional guilds and new types of metabolism. However, few practical tools are available to effectively reduce in situ soil N2O flux. Combating the negative impacts of increasing N2O fluxes poses considerable challenges and will be ineffective without successfully incorporating microbially regulated N2O processes into ecosystem modeling and mitigation strategies. Here, we synthesize the latest knowledge of (i) the key microbial pathways regulating N2O production and consumption processes in terrestrial ecosystems and the critical environmental factors influencing their occurrence, and (ii) the relative contributions of major biological pathways to soil N2O emissions by analyzing available natural isotopic signatures of N2O and by using stable isotope enrichment and inhibition techniques. We argue that it is urgently necessary to incorporate microbial traits into biogeochemical ecosystem modeling in order to increase the estimation reliability of N2O emissions. We further propose a molecular methodology oriented framework from gene to ecosystem scales for more robust prediction and mitigation of future N2O emissions. PMID:25934121

  16. 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

  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

    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.

  19. 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

  20. 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.

  1. 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

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

    PubMed

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

    PubMed

    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

    2016-07-27

    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.

  4. 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.

  5. 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

  6. 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.

  7. Suppression of chemotaxis to corneal inflammation by nitrous oxide.

    PubMed

    Kripke, B J; Kupferman, A; Luu, K C

    1987-11-01

    Immune competency is depressed in the perioperative period. The role of anesthetic agents in immune reactivity remains unclear. The chemotactic migration of polymorphonuclear leukocytes (PMNs) to the cornea of rabbits injured by clove oil was studied. PMNs were previously radiolabeled with tritiated (3H) thymidine. Immediately following injury, the rabbits entered isolation chambers and breathed either air or air containing 10%, 20% or 40% nitrous oxide (N2O) for 24 hours. After sacrifice, the radioactivity of a 10 mm corneal button, removed by trephination, was determined by scintillation counting technique. Peripheral blood was obtained for hemoglobin, white cell and platelet count. The N2O dosage affected on the migration of PMNs to the cornea. 3H was decreased 15.4% by 20% N2O and 38.8% for 40% N2O-exposed rabbits. Peripheral blood values did not differ. N2O can suppress chemotaxis of PMNs in the rabbit, thereby adversely affecting the inflammatory component of immune defense. PMID:3130236

  8. Aerobic Denitrifying Bacteria That Produce Low Levels of Nitrous Oxide

    PubMed Central

    Takaya, Naoki; Catalan-Sakairi, Maria Antonina B.; Sakaguchi, Yasushi; Kato, Isao; Zhou, Zhemin; Shoun, Hirofumi

    2003-01-01

    Most denitrifiers produce nitrous oxide (N2O) instead of dinitrogen (N2) under aerobic conditions. We isolated and characterized novel aerobic denitrifiers that produce low levels of N2O under aerobic conditions. We monitored the denitrification activities of two of the isolates, strains TR2 and K50, in batch and continuous cultures. Both strains reduced nitrate (NO3−) to N2 at rates of 0.9 and 0.03 μmol min−1 unit of optical density at 540 nm−1 at dissolved oxygen (O2) (DO) concentrations of 39 and 38 μmol liter−1, respectively. At the same DO level, the typical denitrifier Pseudomonas stutzeri and the previously described aerobic denitrifier Paracoccus denitrificans did not produce N2 but evolved more than 10-fold more N2O than strains TR2 and K50 evolved. The isolates denitrified NO3− with concomitant consumption of O2. These results indicated that strains TR2 and K50 are aerobic denitrifiers. These two isolates were taxonomically placed in the β subclass of the class Proteobacteria and were identified as P. stutzeri TR2 and Pseudomonas sp. strain K50. These strains should be useful for future investigations of the mechanisms of denitrifying bacteria that regulate N2O emission, the single-stage process for nitrogen removal, and microbial N2O emission into the ecosystem. PMID:12788710

  9. Neurobiology of nitrous oxide-induced antinociceptive effects.

    PubMed

    Fujinaga, Masahiko; Maze, Mervyn

    2002-04-01

    Nitrous oxide (N2O), or laughing gas, has been used for clinical anesthesia for more than a century and is still commonly used. While the anesthetic/hypnotic mechanisms of N2O remain largely unknown, the underlying mechanisms of its analgesic/antinociceptive effects have been elucidated during the last several decades. Evidence to date indicate that N2O induces opioid peptide release in the periaqueductal gray area of the midbrain leading to the activation of the descending inhibitory pathways, which results in modulation of the pain/nociceptive processing in the spinal cord. The types of opioid peptide induced by N2O and the subtypes of opioid receptors that mediate the antinociceptive effects of N2O appear to depend on various factors including the species and/or strain, the regions of the brain, and the paradigms of behavior testing used for the experiments. Among three types of descending inhibitory pathways, the descending noradrenergic inhibitory pathway seems to play the most prominent role. The specific elements involved are now being resolved. PMID:11936558

  10. Boreal forest soil nitrous oxide production and consumption responds positively to temperature and a warmer climate

    NASA Astrophysics Data System (ADS)

    Buckeridge, K. M.; Edwards, K.; Ziegler, S. E.; Billings, S. A.

    2014-12-01

    The greenhouse gas nitrous oxide (N2O) is both produced and consumed in soils. In strict denitrification, nitrogen (N)-oxides are reduced stepwise by microbial enzymes until dinitrogen (N2) is produced. N2O may be lost and/or consumed during this process, by microbes that may or may not possess the enzyme required for the final step of the reduction chain. In cold, N-limited, boreal forest soils consumption may dominate, resulting in low net N2O flux to the atmosphere, though the ubiquity of this pattern and the temperature response of these processes are unclear. To accurately predict the temperature response of net soil efflux of N2O in the boreal biome, we must understand fundamental, temperature responses of the boreal soil denitrifier community. Using boreal forest organic and mineral soils collected from three climate regions along the Newfoundland and Labrador Boreal Ecosystem Latitudinal Transect, Canada, we measured soil N2O fluxes during ~60 h lab incubations, in which conditions for denitrification were optimized. Organic soils from the warmer climate and incubated at the warmest temperature produced the most N2O. These soils also experienced net consumption of N2O earlier in the incubation than other soils. All mineral soils, regardless of location along the climate gradient, exhibited net N2O consumption earliest in the incubation at the warmest incubation temperature. Ongoing analyses of headspace N2O and N2 d15N and relative abundances of denitrifying communities during the incubation will reveal mechanisms driving changes in [N2O] over time, but these data suggest warmer temperatures in these boreal soils promote enhanced rates of both N2O production and consumption, with 'hot moments' of net N2O efflux during which production far exceeds consumption. If these results are applicable in situ, a warming climate may result in greater net N2O flux from boreal forest soils such as these.

  11. 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.

  12. Impact of biochar on nitrous oxide emissions from upland rice.

    PubMed

    Petter, Fabiano André; de Lima, Larissa Borges; Marimon Júnior, Ben Hur; Alves de Morais, Leidimar; Marimon, Beatriz Schwantes

    2016-03-15

    The objective of this research was to assess the emission of nitrous oxide (N2O) from soil amended with biochar in the culture of upland rice. The experiment was conducted in the field in a Cerrado Haplic Plinthosol under randomized block experimental design. The treatments consisted of fertilization with 100 kg N ha(-1) split into two applications, 60% at sowing and 40% at 45 days after crop emergence, combined with four doses of biochar (0, 8, 16 and 32 Mg ha(-1)), with four replications. The application of N and the emission of N2O, moisture retention and soil temperature, respiration (C-CO2), microbial biomass carbon in the soil (C-SMB), total nitrogen (TN), pH and agronomic efficiency in N use (AENu) were evaluated five years after the application of biochar. There was a significant correlation of the application of biochar with moisture retention (r = 0.94**), N2O emission (r = 0.86**) and soil pH (r = 0.65*), and N2O emissions showed a positive correlation (p < 0.05) with soil moisture (r = 0.77**) and pH (r = 0.66*). Thus the highest N2O emissions were observed shortly after N fertilization and in the treatments with 32 Mg ha(-1) of biochar. Despite the higher N2O emissions from the application of 32 Mg ha(-1) of biochar, the emission factor was lower (0.81%) than the maximum recommended by the IPCC. The higher N2O emissions with application of biochar are offset by more efficient use of N and consequently the possibility of reduction of applied doses. PMID:26716573

  13. 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.

  14. 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

  15. Non-growing season nitrous oxide fluxes from agricultural soils

    NASA Astrophysics Data System (ADS)

    Kariyapperuma Athukoralage, Kumudinie

    A two-year field experiment was conducted at the Arkell Research Station, Ontario, Canada to evaluate composting as a mitigation strategy for greenhouse gases (GHGs). The objectives were to quantify and compare non-growing season nitrous oxide (N2O) fluxes from agricultural soils after fall manure application of composted and untreated liquid swine manure. Nitrous oxide fluxes were measured using a micrometeorological method. Compared to untreated liquid swine manure (LSM), composted swine manure (CSM) resulted in 57% reduction of soil N2O emissions during February to April in 2005, but emissions during the same period in 2006 were not affected by treatments. This effect was related to fall and winter weather conditions with the significant reduction occurring in the year when soil freezing was more pronounced. The DNDC (DeNitrification-DeComposition) model was tested against data measured during the non-growing seasons from 2000 to 2004, for farming with conventional management at the Elora Research Station, Ontario, Canada. The objective was to assess the ability of the DNDC model to simulate non-growing season N2O fluxes from soils in southwestern Ontario. Comparison between model-simulated and measured data indicated that background fluxes were relatively well predicted. The spring thaw N2O flux event was correctly timed by the DNDC model, but was smaller than the measured spring thaw event. Though there was no N2O emission event measured in early May, the DNDC model predicted a large event, simultaneous with the physical release of predicted ice-trapped N2O. Removing the large and late predicted emission peak and increasing the contribution of newly produced N2O due to denitrification to the early spring thaw event were proposed. Three data sets from studies conducted in Ontario, Canada were used to estimate and compare the overall GHG (N2O and methane) emissions from LSM and CSM. Compared to LSM storage, the composting process reduced GHG emissions by 35% (CO

  16. Impact of implantation on the properties of N 2O-nitrided oxides of p +- and n +-gate MOS devices

    NASA Astrophysics Data System (ADS)

    Naumova, O. V.; Fomin, B. I.; Sakharova, N. V.; Ilnitsky, M. A.; Popov, V. P.

    2009-05-01

    The impact of the gate implantation on properties of N2O-nitrided thermal oxides MOS dielectric layers were evaluated in this study via current-voltage, j-ramp and current-temperature techniques. The data obtained show that implantation with boron of poly-Si gates can result in generation of border traps in oxides. The energy position of traps generated in the oxides after Fowler-Nordheim voltage stress and after hard breakdown treatments were evaluated.

  17. 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.

  18. 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.

  19. 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.

  20. Incomplete Denitrification Causes Rapid Nitrous Oxide Cycling in the Oceanic Oxygen Minimum Zones

    NASA Astrophysics Data System (ADS)

    Babbin, A. R.; Ward, B. B.; Stocker, R.

    2015-12-01

    Nitrous oxide (N2O) is a powerful greenhouse gas and a major cause of stratospheric ozone depletion, yet its sources and sinks remain poorly quantified in the oceans. We used isotope tracers to directly measure N2O reduction rates in the eastern tropical North Pacific. Because of incomplete denitrification, N2O cycling rates are an order of magnitude higher than predicted by current models in suboxic regions, and the spatial distribution suggests strong dependence on both organic carbon and dissolved oxygen concentrations. Furthermore, N2O turnover is 20 times higher than the net atmospheric efflux. The rapid rate of this cycling coupled to an expected expansion of suboxic ocean waters implies future increases in N2O emissions.

  1. Quantum cascade laser photoacoustic detection of nitrous oxide released from soils for biofuel production

    NASA Astrophysics Data System (ADS)

    Couto, F. M.; Sthel, M. S.; Castro, M. P. P.; da Silva, M. G.; Rocha, M. V.; Tavares, J. R.; Veiga, C. F. M.; Vargas, H.

    2014-12-01

    In order to investigate the generation of greenhouse gases in sugarcane ethanol production chain, a comparative study of N2O emission in artificially fertilized soils and soils free from fertilizers was carried out. Photoacoustic spectroscopy using quantum cascade laser with an emission ranging from 7.71 to 7.88 µm and differential photoacoustic cell were applied to detect nitrous oxide (N2O), an important greenhouse gas emitted from soils cultivated with sugar cane. Owing to calibrate the experimental setup, an initial N2O concentration was diluted with pure nitrogen and detection limit of 50 ppbv was achieved. The proposed methodology was selective and sensitive enough to detect N2O from no fertilized and artificially fertilized soils. The measured N2O concentration ranged from ppmv to ppbv.

  2. 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,...

  3. 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,...

  4. 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,...

  5. 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,...

  6. 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,...

  7. 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.

  8. Management controls on nitrous oxide emissions from row crop agriculture

    NASA Astrophysics Data System (ADS)

    Gelfand, I.; Shcherbak, I.; Millar, N.; Robertson, G. P.

    2011-12-01

    Agriculture is a significant source of the potent greenhouse gas (GHG) nitrous oxide (N2O), accounting for ~70% of total anthropic N2O emissions in the US primarily as a result of N fertilizer application. Emissions of N2O are the largest contributor to the global warming potential of row-crop agriculture. Management, including choice of crop type and rotation strongly impacts N2O emissions, but continuous emissions data from row-crops over multiple rotations are lacking. Empirical quantification of these long-term emissions and the development of crop- and rotation-specific N2O emission factors are vital for improving estimates of agricultural GHG emissions, important for informing management practices to reduce agriculture's GHG footprint, and developing mitigation protocols for environmental markets. Over 20 years we measured soil N2O emissions and calculated crop and management specific emission factors in four continuous rotations of corn (Zea mays) - soybean (Glycine max) - wheat (Triticum aestivum) under conventional tillage (CT), zero tillage (NT), low chemical input (LI), and biologically (Org) based management. Two of these systems (LI and Org) included winter cover crops, red clover (Trifolium pratense) or ray (Secale cereale). While average soil N2O fluxes in all systems where similar (2.9±0.2 to 3.8±0.5 g N2O-N ha-1 d-1), there was a significant interaction of total emissions with crop and phase. Surprisingly, the lowest total emissions from the corn period of the rotation were from CT, and the highest from LI, with 608±4 and 983±8 g N2O-N ha-1 crop year-1, respectively. Total emissions during the wheat period of the rotation showed the opposite trend, with total emissions of 942±7 and 524±38 g N2O-N ha-1 crop year-1, for CT ant LI, respectively. Total emissions from the soybean period of the rotation were highest under NT and lowest under CT management (526±5 and 296±2 g N2O-N ha-1 crop year-1, respectively). Emission efficiency, N2O emitted

  9. 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.

  10. 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.

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

    PubMed

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

    2015-02-03

    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.

  12. 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.

  13. 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.

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

    PubMed Central

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

    2015-01-01

    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. PMID:25644694

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

    PubMed

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

    2015-01-01

    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. PMID:25644694

  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. PMID:22830624

  17. Land Use Change Effects on Nitrous Oxide Emissions in Tropical Regions

    NASA Astrophysics Data System (ADS)

    Keller, M.

    2003-12-01

    Soil emissions of nitrous oxide (N2O) are the single most important natural source for this gas and also the single largest anthropogenic contribution to the global budget of N2O. The availability of oxygen, inorganic nitrogen, and organic carbon are the three principle limitations to soil emissions of N2O. These limitations play the same roles in soils globally, so there is nothing intrinsically different about processes in the tropical regions versus the temperate and boreal zones. However, the tropical regions are a far more important natural source of soil derived N2O and will increase greatly in importance for anthropogenic emissions in the future. Both the area dedicated to agriculture and the quantity of nitrogenous fertilizer applied are relatively stable in the temperate zone while they are increasing rapidly in the tropical zone. When considering N2O emissions, there are two important eco-regions in the tropics, savannas and forests. In both of these regions, natural ecosystems are being converted to pasture lands and to intensive agriculture. N2O emissions from natural savannas are minimal. Conversion to pasture and to agriculture has limited effects. In savanna systems the natural limitation of nitrogen and the abundance of oxygen combine to minimize N2O emissions from soils. In the forested regions, the situation is different. Tropical forests, particularly in humid areas, are nitrogen rich. Conversion of forests to pastures may lead to a brief pulse (from a few months to a decade) of elevated nitrous oxide emissions. Unless pastures are fertilized, their emissions are generally far below native forest emissions of N2O. Where N fertilizer use is heavy, conversion of forests (or pastures) to agriculture may lead to significant increases in N2O emissions. But under extensive management or careful intensive management, it is possible for agricultural systems in the humid tropics to have lower N2O emissions than native ecosystems.

  18. 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.

  19. 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. PMID:27161136

  20. 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

  1. Nitrous Oxide Emissions From Livestock Waste Under Oxic and Anoxic Conditions

    NASA Astrophysics Data System (ADS)

    Molodovskaya, M. S.; Singurindy, O.; Richards, B. K.; Giri, S. K.; Steenhuis, T. S.

    2005-12-01

    Nitrous oxide (N2O) gas has been identified as an important contributor to atmospheric greenhouse effect. The largest agricultural N2O emissions are from fertilizer applications, tillage and livestock on farms. Livestock sources include manure storage, handling, and land application, and N2O emissions from those manure management practices can be very significant. The development of manure best management practices to minimize the contribution of livestock to the global greenhouse effect requires knowledge of the environmental and atmospheric conditions that affect nitrous oxide emission rates. In this study we estimated nitrous oxide emissions from fresh dairy manure under several air exchange rates creating different oxic and anoxic conditions. During a three weeks period, gas flows with and without oxygen (compressed air and dinitrogen) at different rates were continuously passed through manure samples incubated at 25°C. Nitrogen transformations in manure and N2O emissions were quantified as a function of flow rate. We found that manure treatments involving exposure to the air could be significant source of nitrogen gaseous emissions. The rates and dynamics of N2O emissions were substantially impacted by oxygen and total ammoniac nitrogen content, which, in turn, was regulated by the aeration rate. The higher oxygen availability resulted from high aeration significantly enhanced nitrification and inhibited denitrification. Increasing airflow rates led to higher N losses through ammonia volatilization and, consequently, to the faster depletion of total N stock and reducing potential for N2O formation. N-N2O losses varied from 1.6 to 4.2% of manure total nitrogen content. The maximum N2O emissions were observed at moderate aeration rates.

  2. 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...

  3. 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 ...

  4. 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...

  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. 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...

  7. Evaluation of factors affecting nitrous oxide emission and N transformation in a sandy loam soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A better understanding of the complex factors affecting nitrous oxide (N2O) emission and potential mitigation practices will assist in developing strategies to improve the sustainability of agricultural production systems. Using surface soil collected from a pomegranate orchard, a series of laborato...

  8. 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 ...

  9. 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...

  10. AMMONIA REMOVAL AND NITROUS OXIDE PRODUCTION IN GAS-PHASE COMPOST BIOFILTERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biofiltration technology is widely utilized for treating ammonia gas (NH3), with one of its potential detrimental by-products being nitrous oxide (N2O), a greenhouse gas approximately 300 times more reactive to infrared than CO2. The present work intends to provide the relation between NH3 removal d...

  11. 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.

  12. 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.

  13. Nitrous Oxide Emissions from Bare Peat Surfaces on Permafrost Peatlands

    NASA Astrophysics Data System (ADS)

    Repo, M. E.; Pitkämäki, A.; Biasi, C.; Seppälä, M.; Martikainen, P. J.

    2009-12-01

    Pronounced warming predicted for the arctic areas may enhance the release of soil carbon and nitrogen as greenhouse gases to the atmosphere. While carbon dioxide and methane fluxes in high-latitude ecosystems have been widely investigated, fewer studies have been published on nitrous oxide (N2O) dynamics in the North. Although most pristine ecosystems in the Arctic do not emit N2O due to strict nitrogen limitation, recent findings show that there are specific surfaces capable of high N2O production and release (Repo et al., 2009). In this study we used a static chamber technique to study N2O emissions from bare peat surfaces on two subarctic permafrost peatland types, peat plateau and palsa mire. The peat plateau site is located in the discontinuous permafrost zone in Komi Republic, Russia (67°03' N, 62°57' E). Field data from this Russian site from snow-free season 2007 showed high emissions from peat circles (bare peat surfaces affected by cryoturbation; 1.9 to 31 mg N2O m-2 d-1) and negligible N2O release from all the vegetated surfaces (Repo et al. 2009). Peat circles were emitting N2O at rates comparable to those measured typically from agricultural and tropical soils. These observations were confirmed by field campaign in 2008. Partly vegetated palsas on the top of the peat plateau, included in the study in 2008, showed also significant N2O emissions, intermediate to those from peat circles and fully vegetated sites. No particularly high peak emissions were observed during cold season from either of the studied surfaces, in contrast to what has been reported from many boreal soils. To get evidence on the spatial coverage of high N2O emissions from subarctic peatlands, N2O emissions were measured from three palsa mires in Finnish Lapland (69°34'-69°50' N, 26°10'-27°10' E) during a short campaign in peak season 2009. The region has less permafrost extent and milder climatic conditions than the Russian site. Bare peat surfaces on palsas, created by wind

  14. 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.

  15. 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...

  16. Grazing-induced reduction of natural nitrous oxide release from continental steppe.

    PubMed

    Wolf, Benjamin; Zheng, Xunhua; Brüggemann, Nicolas; Chen, Weiwei; Dannenmann, Michael; Han, Xingguo; Sutton, Mark A; Wu, Honghui; Yao, Zhisheng; Butterbach-Bahl, Klaus

    2010-04-01

    Atmospheric concentrations of the greenhouse gas nitrous oxide (N(2)O) have increased significantly since pre-industrial times owing to anthropogenic perturbation of the global nitrogen cycle, with animal production being one of the main contributors. Grasslands cover about 20 per cent of the temperate land surface of the Earth and are widely used as pasture. It has been suggested that high animal stocking rates and the resulting elevated nitrogen input increase N(2)O emissions. Internationally agreed methods to upscale the effect of increased livestock numbers on N(2)O emissions are based directly on per capita nitrogen inputs. However, measurements of grassland N(2)O fluxes are often performed over short time periods, with low time resolution and mostly during the growing season. In consequence, our understanding of the daily and seasonal dynamics of grassland N(2)O fluxes remains limited. Here we report year-round N(2)O flux measurements with high and low temporal resolution at ten steppe grassland sites in Inner Mongolia, China. We show that short-lived pulses of N(2)O emission during spring thaw dominate the annual N(2)O budget at our study sites. The N(2)O emission pulses are highest in ungrazed steppe and decrease with increasing stocking rate, suggesting that grazing decreases rather than increases N(2)O emissions. Our results show that the stimulatory effect of higher stocking rates on nitrogen cycling and, hence, on N(2)O emission is more than offset by the effects of a parallel reduction in microbial biomass, inorganic nitrogen production and wintertime water retention. By neglecting these freeze-thaw interactions, existing approaches may have systematically overestimated N(2)O emissions over the last century for semi-arid, cool temperate grasslands by up to 72 per cent.

  17. From the Ground Up: Global Nitrous Oxide Sources are Constrained by Stable Isotope Values

    PubMed Central

    Snider, David M.; Venkiteswaran, Jason J.; Schiff, Sherry L.; Spoelstra, John

    2015-01-01

    Rising concentrations of nitrous oxide (N2O) in the atmosphere are causing widespread concern because this trace gas plays a key role in the destruction of stratospheric ozone and it is a strong greenhouse gas. The successful mitigation of N2O emissions requires a solid understanding of the relative importance of all N2O sources and sinks. Stable isotope ratio measurements (δ15N-N2O and δ18O-N2O), including the intramolecular distribution of 15N (site preference), are one way to track different sources if they are isotopically distinct. ‘Top-down’ isotope mass-balance studies have had limited success balancing the global N2O budget thus far because the isotopic signatures of soil, freshwater, and marine sources are poorly constrained and a comprehensive analysis of global N2O stable isotope measurements has not been done. Here we used a robust analysis of all available in situ measurements to define key global N2O sources. We showed that the marine source is isotopically distinct from soil and freshwater N2O (the continental source). Further, the global average source (sum of all natural and anthropogenic sources) is largely controlled by soils and freshwaters. These findings substantiate past modelling studies that relied on several assumptions about the global N2O cycle. Finally, a two-box-model and a Bayesian isotope mixing model revealed marine and continental N2O sources have relative contributions of 24–26% and 74–76% to the total, respectively. Further, the Bayesian modeling exercise indicated the N2O flux from freshwaters may be much larger than currently thought. PMID:25811179

  18. Nitrous oxide fluxes in turfgrass: effects of nitrogen fertilization rates and types.

    PubMed

    Bremer, Dale J

    2006-01-01

    Urban ecosystems are rapidly expanding and their effects on atmospheric nitrous oxide (N2O) inventories are unknown. Our objectives were to: (i) measure the magnitude, seasonal patterns, and annual emissions of N2O in turfgrass; (ii) evaluate effects of fertilization with a high and low rate of urea N; and (iii) evaluate effects of urea and ammonium sulfate on N2O emissions in turfgrass. Nitrogen fertilizers were applied to turfgrass: (i) urea, high rate (UH; 250 kg N ha(-1) yr(-1)); (ii) urea, low rate (UL; 50 kg N ha(-1) yr(-1)); and (iii) ammonium sulfate, high rate (AS; 250 kg N ha(-1) y(-1)); high N rates were applied in five split applications. Soil fluxes of N2O were measured weekly for 1 yr using static surface chambers and analyzing N2O by gas chromatography. Fluxes of N2O ranged from -22 microg N2O-N m(-2) h(-1) during winter to 407 microg N2O-N m(-2) h(-1) after fall fertilization. Nitrogen fertilization increased N2O emissions by up to 15 times within 3 d, although the amount of increase differed after each fertilization. Increases were greater when significant precipitation occurred within 3 d after fertilization. Cumulative annual emissions of N2O-N were 1.65 kg ha(-1) in UH, 1.60 kg ha(-1) in AS, and 1.01 kg ha(-1) in UL. Thus, annual N2O emissions increased 63% in turfgrass fertilized at the high compared with the low rate of urea, but no significant effects were observed between the two fertilizer types. Results suggest that N fertilization rates may be managed to mitigate N2O emissions in turfgrass ecosystems.

  19. Nitrous oxide misuse and vitamin B12 deficiency.

    PubMed

    Massey, Thomas H; Pickersgill, Trevor T; J Peall, Kathryn

    2016-01-01

    A 36-year-old man presented to hospital with a 5-week history of ascending limb paraesthesiae and balance difficulties. He had no medical or travel history of note, but admitted habitual nitrous oxide (N2O) inhalation. Neurological examination revealed a sensory ataxia with pseudoathetosis in the upper limbs and reduced vibration sensation to the hips bilaterally. Significant investigation results included a low serum vitamin B12 concentration, mild macrocytosis and raised serum homocysteine concentration. T2 MRI of the spinal cord demonstrated increased signal extending from C1 to T11 in keeping with a longitudinal myelitis. The patient was diagnosed with a myeloneuropathy secondary to vitamin B12 deficiency, resulting from heavy N2O inhalation. He was treated with intramuscular vitamin B12 injections and received regular physiotherapy. At discharge, he was able to mobilise short distances with the aid of a zimmer frame, and was independently mobile 8 weeks later. PMID:27247211

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

    NASA Astrophysics Data System (ADS)

    Frame, C. H.; Casciotti, K. L.

    2010-09-01

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

  1. N2O5 oxidizes chloride to Cl2 in acidic atmospheric aerosol.

    PubMed

    Roberts, James M; Osthoff, Hans D; Brown, Steven S; Ravishankara, A R

    2008-08-22

    Molecular chlorine (Cl2) is an important yet poorly understood trace constituent of the lower atmosphere. Although a number of mechanisms have been proposed for the conversion of particle-bound chloride (Cl-) to gas-phase Cl2, the detailed processes involved remain uncertain. Here, we show that reaction of dinitrogen pentoxide (N2O5) with aerosol-phase chloride yields Cl2 at low pH (<2) and should constitute an important halogen activation pathway in the atmosphere.

  2. 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.

  3. Mechanisms of transient nitric oxide and nitrous oxide production in a complex biofilm.

    PubMed

    Schreiber, Frank; Loeffler, Birte; Polerecky, Lubos; Kuypers, Marcel M M; de Beer, Dirk

    2009-11-01

    Nitric oxide (NO) and nitrous oxide (N(2)O) are formed during N-cycling in complex microbial communities in response to fluctuating molecular oxygen (O(2)) and nitrite (NO(2)(-)) concentrations. Until now, the formation of NO and N(2)O in microbial communities has been measured with low spatial and temporal resolution, which hampered elucidation of the turnover pathways and their regulation. In this study, we combined microsensor measurements with metabolic modeling to investigate the functional response of a complex biofilm with nitrifying and denitrifying activity to variations in O(2) and NO(2)(-). In steady state, NO and N(2)O formation was detected if ammonium (NH(4)(+)) was present under oxic conditions and if NO(2)(-) was present under anoxic conditions. Thus, NO and N(2)O are produced by ammonia-oxidizing bacteria (AOB) under oxic conditions and by heterotrophic denitrifiers under anoxic conditions. NO and N(2)O formation by AOB occurred at fully oxic conditions if NO(2)(-) concentrations were high. Modeling showed that steady-state NO concentrations are controlled by the affinity of NO-consuming processes to NO. Transient accumulation of NO and N(2)O occurred upon O(2) removal from, or NO(2)(-) addition to, the medium only if NH(4)(+) was present under oxic conditions or if NO(2)(-) was already present under anoxic conditions. This showed that AOB and heterotrophic denitrifiers need to be metabolically active to respond with instantaneous NO and N(2)O production upon perturbations. Transiently accumulated NO and N(2)O decreased rapidly after their formation, indicating a direct effect of NO on the metabolism. By fitting model results to measurements, the kinetic relationships in the model were extended with dynamic parameters to predict transient NO release from perturbed ecosystems. PMID:19516281

  4. 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

  5. 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.

  6. 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

    2012-05-01

    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.

  7. 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.

  8. 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.

  9. Origin and fluxes of nitrous oxide along a latitudinal transect in western North Pacific: Controls and regional significance

    NASA Astrophysics Data System (ADS)

    Breider, Florian; Yoshikawa, Chisato; Abe, Hitomi; Toyoda, Sakae; Yoshida, Naohiro

    2015-07-01

    Nitrous oxide (N2O) is an atmospheric trace gas playing an important role in both radiative forcing and stratospheric ozone depletion. The oceans are the second most important natural source of N2O. The magnitude of the flux of this source is poorly constrained. Moreover, the relative importance of the microbial processes leading to the formation or the consumption of N2O in oceans remains unclear. We present here fluxes and isotope and isotopomer signatures of N2O measured at three stations located along a latitudinal transect in subtropical and subarctic western North Pacific. These results indicate that about 30% to 55% of the oceanic flux of N2O to the atmosphere originates from the deep euphotic and shallow aphotic zones. The sea-to-air fluxes of N2O calculated using an isotope mass balance model indicate that the emission rate of N2O in subarctic waters is about 2 times higher than in oligotrophic subtropical waters suggesting that nutrient-rich water coming from the western subarctic gyre stimulates the N2O production. Moreover, isotopomer analysis has revealed that in shallow water N2O originates from nitrification and nitrifier denitrification processes, and its distribution in the water column is partly controlled by the incident solar radiation. The results of this study contribute to better constrain the global N2O budget and provide important information to better predict the future evolution of the oceanic emissions of N2O.

  10. 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

  11. 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

  12. 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.

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

    PubMed

    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 m(3)/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

  14. Source identification of nitrous oxide on autotrophic partial nitrification in a granular sludge reactor.

    PubMed

    Rathnayake, R M L D; Song, Y; Tumendelger, A; Oshiki, M; Ishii, S; Satoh, H; Toyoda, S; Yoshida, N; Okabe, S

    2013-12-01

    Emission of nitrous oxide (N2O) during biological wastewater treatment is of growing concern since N2O is a major stratospheric ozone-depleting substance and an important greenhouse gas. The emission of N2O from a lab-scale granular sequencing batch reactor (SBR) for partial nitrification (PN) treating synthetic wastewater without organic carbon was therefore determined in this study, because PN process is known to produce more N2O than conventional nitrification processes. The average N2O emission rate from the SBR was 0.32 ± 0.17 mg-N L(-1) h(-1), corresponding to the average emission of N2O of 0.8 ± 0.4% of the incoming nitrogen load (1.5 ± 0.8% of the converted NH4(+)). Analysis of dynamic concentration profiles during one cycle of the SBR operation demonstrated that N2O concentration in off-gas was the highest just after starting aeration whereas N2O concentration in effluent was gradually increased in the initial 40 min of the aeration period and was decreased thereafter. Isotopomer analysis was conducted to identify the main N2O production pathway in the reactor during one cycle. The hydroxylamine (NH2OH) oxidation pathway accounted for 65% of the total N2O production in the initial phase during one cycle, whereas contribution of the NO2(-) reduction pathway to N2O production was comparable with that of the NH2OH oxidation pathway in the latter phase. In addition, spatial distributions of bacteria and their activities in single microbial granules taken from the reactor were determined with microsensors and by in situ hybridization. Partial nitrification occurred mainly in the oxic surface layer of the granules and ammonia-oxidizing bacteria were abundant in this layer. N2O production was also found mainly in the oxic surface layer. Based on these results, although N2O was produced mainly via NH2OH oxidation pathway in the autotrophic partial nitrification reactor, N2O production mechanisms were complex and could involve multiple N2O production pathways.

  15. 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.

  16. 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...

  17. 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 ...

  18. 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.

  19. 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.

  20. 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. PMID:27134026

  1. Effect of oxic and anoxic conditions on nitrous oxide emissions from nitrification and denitrification processes.

    PubMed

    Rassamee, Varit; Sattayatewa, Chakkrid; Pagilla, Krishna; Chandran, Kartik

    2011-09-01

    A lab-scale sequencing batch reactor fed with real municipal wastewater was used to study nitrous oxide (N(2)O) emissions from simulated wastewater treatment processes. The experiments were performed under four different controlled conditions as follows: (1) fully aerobic, (2) anoxic-aerobic with high dissolved oxygen (DO) concentration, (3) anoxic-aerobic with low DO concentration, and 4) intermittent aeration. The results indicated that N(2)O production can occur from both incomplete nitrification and incomplete denitrification. N(2)O production from denitrification was observed in both aerobic and anoxic phases. However, N(2)O production from aerobic conditions occurred only when both low DO concentrations and high nitrite concentration existed simultaneously. The magnitude of N(2) O produced via anoxic denitrification was lower than via oxic denitrification and required the presence of nitrite. Changes in DO, ammonium, and nitrite concentrations influenced the magnitude of N(2)O production through denitrification. The results also suggested that N(2)O can be produced from incomplete denitrification and then released to the atmosphere during aeration phase due to air stripping. Therefore, biological nitrogen removal systems should be optimized to promote complete nitrification and denitrification to minimize N(2)O emissions.

  2. [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.

  3. [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. PMID:25223043

  4. 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

    2016-01-01

    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

  5. 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

  6. Intraoperative Development of Tension Pneumocephalus in a Patient Undergoing Repair of a Cranial-Dural Defect Under Nitrous Oxide Anesthesia.

    PubMed

    Singh, Mansher; Vasudeva, Viren S; Rios Diaz, Arturo J; Dunn, Ian F; Caterson, Edward J

    2015-01-01

    Rapid buildup of gas within the cranial vault can result in a life-threatening condition known as "tension pneumocephalus," necessitating immediate surgical intervention. Nitrous oxide (N2O), a commonly used inhaled anesthetic, is associated with the development of tension pneumocephalus and its role in neurosurgical procedures has been debated in the literature. We present a case of tension pneumocephalus with preexisting pneumocephalus secondary to the usage of N2O as an inhaled anesthetic. Included is a literature review of studies discussing the role of N2O in the development of tension pneumocephalus. N2O is associated with tension pneumocephalus especially in the setting of preexisting pneumocephalus. Tension pneumocephalus can manifest as Cushing response and immediate decompression is life-saving. Nitrous oxide should be used cautiously in neurosurgical procedures, especially with preexisting pneumocephalus.

  7. Source identification of nitrous oxide emission pathways from a single-stage nitritation-anammox granular reactor.

    PubMed

    Ali, Muhammad; Rathnayake, Rathnayake M L D; Zhang, Lei; Ishii, Satoshi; Kindaichi, Tomonori; Satoh, Hisashi; Toyoda, Sakae; Yoshida, Naohiro; Okabe, Satoshi

    2016-10-01

    Nitrous oxide (N2O) production pathway in a signal-stage nitritation-anammox sequencing batch reactor (SBR) was investigated based on a multilateral approach including real-time N2O monitoring, N2O isotopic composition analysis, and in-situ analyses of spatial distribution of N2O production rate and microbial populations in granular biomass. N2O emission rate was high in the initial phase of the operation cycle and gradually decreased with decreasing NH4(+) concentration. The average emission of N2O was 0.98 ± 0.42% and 1.35 ± 0.72% of the incoming nitrogen load and removed nitrogen, respectively. The N2O isotopic composition analysis revealed that N2O was produced via NH2OH oxidation and NO2(-) reduction pathways equally, although there is an unknown influence from N2O reduction and/or anammox N2O production. However, the N2O isotopomer analysis could not discriminate the relative contribution of nitrifier denitrification and heterotrophic denitrification in the NO2(-) reduction pathway. Various in-situ techniques (e.g. microsensor measurements and FISH (fluorescent in-situ hybridization) analysis) were therefore applied to further identify N2O producers. Microsensor measurements revealed that approximately 70% of N2O was produced in the oxic surface zone, where nitrifiers were predominantly localized. Thus, NH2OH oxidation and NO2 reduction by nitrifiers (nitrifier-denitrification) could be responsible for the N2O production in the oxic zone. The rest of N2O (ca. 30%) was produced in the anammox bacteria-dominated anoxic zone, probably suggesting that NO2(-) reduction by coexisting putative heterotrophic denitrifiers and some other unknown pathway(s) including the possibility of anammox process account for the anaerobic N2O production. Further study is required to identify the anaerobic N2O production pathways. Our multilateral approach can be useful to quantitatively examine the relative contributions of N2O production pathways. Good understanding of the

  8. Source identification of nitrous oxide emission pathways from a single-stage nitritation-anammox granular reactor.

    PubMed

    Ali, Muhammad; Rathnayake, Rathnayake M L D; Zhang, Lei; Ishii, Satoshi; Kindaichi, Tomonori; Satoh, Hisashi; Toyoda, Sakae; Yoshida, Naohiro; Okabe, Satoshi

    2016-10-01

    Nitrous oxide (N2O) production pathway in a signal-stage nitritation-anammox sequencing batch reactor (SBR) was investigated based on a multilateral approach including real-time N2O monitoring, N2O isotopic composition analysis, and in-situ analyses of spatial distribution of N2O production rate and microbial populations in granular biomass. N2O emission rate was high in the initial phase of the operation cycle and gradually decreased with decreasing NH4(+) concentration. The average emission of N2O was 0.98 ± 0.42% and 1.35 ± 0.72% of the incoming nitrogen load and removed nitrogen, respectively. The N2O isotopic composition analysis revealed that N2O was produced via NH2OH oxidation and NO2(-) reduction pathways equally, although there is an unknown influence from N2O reduction and/or anammox N2O production. However, the N2O isotopomer analysis could not discriminate the relative contribution of nitrifier denitrification and heterotrophic denitrification in the NO2(-) reduction pathway. Various in-situ techniques (e.g. microsensor measurements and FISH (fluorescent in-situ hybridization) analysis) were therefore applied to further identify N2O producers. Microsensor measurements revealed that approximately 70% of N2O was produced in the oxic surface zone, where nitrifiers were predominantly localized. Thus, NH2OH oxidation and NO2 reduction by nitrifiers (nitrifier-denitrification) could be responsible for the N2O production in the oxic zone. The rest of N2O (ca. 30%) was produced in the anammox bacteria-dominated anoxic zone, probably suggesting that NO2(-) reduction by coexisting putative heterotrophic denitrifiers and some other unknown pathway(s) including the possibility of anammox process account for the anaerobic N2O production. Further study is required to identify the anaerobic N2O production pathways. Our multilateral approach can be useful to quantitatively examine the relative contributions of N2O production pathways. Good understanding of the

  9. 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. PMID:18427710

  10. Nitrous oxide by itself is insufficient to relieve pain due to castration in piglets.

    PubMed

    Rault, J-L; Lay, D C

    2011-10-01

    Surgical castration is performed on most male piglets in the United States. However, castration is painful and analgesics have been considered to relieve pain. Inhalant gases with analgesic properties allow for a fast induction, have short-term and reversible effects, and are a needle-free option. Nitrous oxide (N(2)O; "laughing gas") has been widely used in human surgery and dental offices as an analgesic, sedative, and anxiolytic drug, yet N(2)O has not been thoroughly investigated for use in farm animals. We hypothesized that the analgesic effect of N(2)O could reduce the pain experienced by piglets during or immediately after castration. Twenty-four male piglets, from 12 litters, were castrated at 3 d of age. One piglet received N(2)O and a littermate received air as a control. After 150 s of exposure to the gas, castration was performed while the piglet remained exposed to the gas. Agitation scores and total vocalization length were recorded during castration. Behavioral observations were continued for 3 d postcastration by using a 5-min scan-sampling method for 4 h the first morning and for 2-h periods in the morning and afternoon of each day thereafter. Body weight gain was measured on the day before castration, at 3 d postcastration, and at weaning. Data were analyzed using a mixed model in SAS (Cary, NC). Nitrous oxide successfully induced anesthesia in all N(2)O piglets, as validated by a skin pinch test and the loss of the palpebral reflex. Total vocalization length was shorter in piglets receiving N(2)O during the induction phase (P = 0.003) but was not different during castration itself because piglets receiving N(2)O awoke and vocalized as much as control piglets (P = 0.87). Agitation scores during the whole procedure were reduced in piglets receiving N(2)O in both frequency (P = 0.005) and intensity (P = 0.026). For 2 h after castration, piglets receiving N(2)O displayed less huddling behavior than did control piglets (P = 0.01). Over the 3 d

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

    NASA Astrophysics Data System (ADS)

    Frame, C. H.; Casciotti, K. L.

    2010-04-01

    Nitrous oxide (N2O) is a trace gas that contributes to greenhouse warming of the atmosphere and stratospheric ozone depletion. The N2O yield from nitrification (moles N2O-N produced/mole ammonium-N consumed) has been used to estimate marine N2O production rates from measured nitrification rates and global estimates of oceanic export production. However, the N2O yield from nitrification is not constant. Previous culture-based measurements indicate that N2O yield increases as oxygen (O2) concentration decreases and as nitrite (NO2-) concentration increases. These results were obtained in substrate-rich conditions and may not reflect N2O production in the ocean. Here, we have measured yields of N2O from cultures of the marine β-proteobacterium Nitrosomonas marina C-113a as they grew on low-ammonium (50 μM) media. These yields were lower than previous reports, between 4×10-4 and 7×10-4 (moles N/mole N). The observed impact of O2 concentration on yield was also smaller than previously reported under all conditions except at high starting cell densities (1.5×10N2O yield with dropping O2 could be reproduced only at cell densities that far exceeded those of ammonia oxidizers in the ocean. The presence of excess NO2- (up to 1 mM) in the growth medium also increased N2O yields by an average of 70% to 87% depending on O2 concentration. We made stable isotopic measurements on N2O from these cultures to identify the biochemical mechanisms behind variations in N2O yield. Based on measurements of δ15N, site preference (SP=δ15Nα - δ15Nβ), and δ18O, we estimate that nitrifier-denitrification produced between 11% and 26% of N2O from cultures

  12. Nitrous oxide emissions from a municipal landfill.

    PubMed

    Rinne, Janne; Pihlatie, Mari; Lohila, Annalea; Thum, Tea; Aurela, Mika; Tuovinen, Juha-Pekka; Laurila, Tuomas; Vesala, Timo

    2005-10-15

    The first measurements of nitrous oxide (N20) emissions from a landfill by the eddy covariance method are reported. These measurements were compared to enclosure emission measurements conducted at the same site. The average emissions from the municipal landfill of the Helsinki Metropolitan Area were 2.7 mg N m(-2) h(-1) and 6.0 mg N m(-2) h(-1) measured bythe eddy covariance and the enclosure methods, respectively. The N20 emissions from the landfill are about 1 order of magnitude higher than the highest emissions reported from Northern European agricultural soils, and 2 orders of magnitude higher than the highest emissions reported from boreal forest soils. Due to the small area of landfills as compared to other land-use classes, the total N20 emissions from landfills are estimated to be of minor importance for the total emissions from Finland. Expressed as a greenhouse warming potential (GWP100), the N2O emissions make up about 3% of the total GWP100 emission of the landfill. The emissions measured by the two systems were generally of similar magnitude, with enclosure measurements showing a high small-scale spatial variation. PMID:16295838

  13. Continuous measurements of Nitrous Oxide isotopomers during incubation experiments

    NASA Astrophysics Data System (ADS)

    Nordmann Winther, Malte; Blunier, Thomas; Balslev-Harder, David; Elberling, Bo; Priemé, Anders; Christensen, Søren

    2016-04-01

    Nitrous oxide (N2O) is an important and strong trace greenhouse gas in the atmosphere; it is part of a feed-back loop with climate. N2O is produced by microbes during nitrification and denitrification in the terrestrial and oceanic realm where today 1/3 of the production is estimated to stem from oceanic sources. The position of the isotope 15N in the linear N=N=O molecule can be distinguished between the central or terminal position (the isotopomers of N2O). It has been demonstrated that nitrification and denitrification have a relative preference for the terminal and central position, respectively. Therefore it is claimed that measuring the site preference in N2O allows to determine the responsible production process i.e. nitrification or denitrification. Our recent instrument development in collaboration with Picarro Inc. allows for continuous position dependent δ15N measurements. We present continuous results from incubation experiments with denitrifying bacteria, Pseudomonas Fluorescens and Pseudomonas Chlororaphis. We find bulk isotope effects of -11.3‰ to -8.3‰ for P. Chlororaphis. For P. Fluorescens the isotope effect during production of N2O is in the range -47.7‰ to -35.4‰ and between 1.9‰ and 12.6‰ during N2O reduction. The values for P. Fluorescens is in line with earlier findings, whereas the values for P. Chlororaphis is larger than previously published δ15Nbulk measurements from production. The calculations of the site preference (SP) isotope effect from the measurements of P. Chlororaphis results in values between 8.6‰ and 1.6‰. For P. Fluorescens the calculations results in SP values between -11.6‰ and -0.8‰ during production of N2O and between -8.1‰ and 5.0‰ during reduction of N2O. All measured values of SP are in the range of previously published results for denitrifying bacteria.

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

    PubMed Central

    Hörtnagl, L.; Wohlfahrt, G.

    2015-01-01

    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 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. PMID:25821473

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

    NASA Astrophysics Data System (ADS)

    Hörtnagl, L.; Wohlfahrt, G.

    2014-06-01

    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 more than 95% of the half-hourly fluxes of CH4 and N2O ranging between ±10 and ±1 nmol 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 time scale. 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 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 26/38% of observed CH4/N2O flux variability, and up to 62/75% on shorter time scales in-between management dates. In case of N2O fluxes, we found highest emissions at intermediate soil water contents and at soil temperatures close to zero 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. 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

  17. 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.

  18. 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

  19. 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).

  20. [Contribution of fungi to soil nitrous oxide emission and their research methods: a review].

    PubMed

    Huang, Ying; Long, Xi-En

    2014-04-01

    Nitrous oxide is an important greenhouse gas. Soil is one major emission source of N2O, which is a by-product of microorganisms-driven nitrification and denitrification processes. Extensive research has demonstrated archaea and bacteria are the predominant contributors in nitrification and denitrification. However, fungi may play a predominant role in the N transformation in a certain soil ecosystem. The fungal contribution to N2O production has been rarely investigated. Here, we reviewed the mechanism of N2O production by soil fungi. The mechanisms of denitrification, autotrophic and heterotrophic nitrification and their key microbes and functional genes were described, respectively. We discriminated the differences in denitrification between bacteria and fungi and discussed the methods being used to determine the contribution of fungi to soil N2O emission, including selective inhibitors, 15N stable isotope probing, isolation and pure culturing and uncultured molecular detection methods. The existing problems and research prospects were also presented.

  1. Relationship between respiratory quotient, nitrification, and nitrous oxide emissions in a forced aerated composting process.

    PubMed

    Tsutsui, Hirofumi; Fujiwara, Taku; Inoue, Daisuke; Ito, Ryusei; Matsukawa, Kazutsugu; Funamizu, Naoyuki

    2015-08-01

    We assessed the relationship between respiratory quotient (RQ) and nitrification and nitrous oxide (N2O) emission in forced aerated composting using lab-scale reactors. Relatively high RQ values from degradation of readily degradable organics initially occurred. RQ then stabilized at slightly lower values, then decreased. Continuous emission of N2O was observed during the RQ decrease. Correlation between nitrification and N2O emission shows that the latter was triggered by nitrification. Mass balances demonstrated that the O2 consumption of nitrification (∼24.8mmol) was slightly higher than that of CO2 emission (∼20.0mmol), indicating that the RQ decrease was caused by the occurrence of nitrification. Results indicate that RQ is a useful index, which not only reflects the bioavailability of organics but also predicts the occurrence of nitrification and N2O emission in forced aerated composting. PMID:25987285

  2. Stable isotope enrichment in stratospheric nitrous oxide

    SciTech Connect

    Rahn, T.; Wahlen, M.

    1997-12-05

    Nitrous oxide is a greenhouse gas that also plays a role in the cycling of stratospheric ozone. Air samples from the lower stratosphere exhibit {sup 15}N/{sup 14}N and {sup 18}O/{sup 16}O enrichment in nitrous oxide, which can be accounted for with a simple model describing an irreversible destruction process. The observed enrichments are quite large and incompatible with those determined for the main stratospheric nitrous oxide loss processes of photolysis and reaction with excited atomic oxygen. Thus, although no stratospheric source needs to be invoked, the data indicate that present understanding of stratospheric nitrous oxide chemistry is incomplete. 21 refs., 1 fig., 1 tab.

  3. 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.

  4. 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. PMID:17655987

  5. 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.

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

    PubMed

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

    2012-01-01

    Nitrous oxide (N(2)O) 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. N(2)O is formed biologically from the oxidation of hydroxylamine (NH(2)OH) or the reduction of nitrite (NO(-) (2)) to NO and further to N(2)O. Our review of the biological pathways for N(2)O 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 N(2)O, while N(2)O formation from NH(2)OH is only performed by ammonia oxidizing bacteria (AOB). In addition to biological pathways, we review important chemical reactions that can lead to NO and N(2)O formation due to the reactivity of NO(-) (2), NH(2)OH, and nitroxyl (HNO). Moreover, biological N(2)O formation is highly dynamic in response to N-imbalance imposed on a system. Thus, understanding NO formation and capturing the dynamics of NO and N(2)O build-up are key to understand mechanisms of N(2)O release. Here, we discuss novel technologies that allow experiments on NO and N(2)O formation at high temporal resolution, namely NO and N(2)O microelectrodes and the dynamic analysis of the isotopic signature of N(2)O with quantum cascade laser absorption spectroscopy (QCLAS). In addition, we introduce other techniques that use the isotopic composition of N(2)O 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

  7. 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

  8. 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.

  9. 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. PMID:26167675

  10. 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.

  11. [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.

  12. Nitrogen source effects on nitrous oxide emissions from irrigated no-till corn.

    PubMed

    Halvorson, Ardell D; Del Grosso, Stephen J; Francesco, Alluvione

    2010-01-01

    Nitrogen fertilization is essential for optimizing crop yields; however, it may potentially increase nitrous oxide (N2O) emissions. The study objective was to assess the ability of commercially available enhanced-efficiency N fertilizers to reduce N2O emissions following their application in comparison with conventional dry granular urea and liquid urea-ammonium nitrate (UAN) fertilizers in an irrigated no-till (NT) corn (Zea mays L.) production system. Four enhanced-efficiency fertilizers were evaluated: two polymer-coated urea products (ESN and Duration III) and two fertilizers containing nitrification and urease inhibitors (SuperU and UAN+AgrotainPlus). Nitrous oxide fluxes were measured during two growing seasons using static, vented chambers and a gas chromatograph analyzer. Enhanced-efficiency fertilizers significantly reduced growing-season N2O-N emissions in comparison with urea, including UAN. SuperU and UAN+AgrotainPlus had significantly lower N2O-N emissions than UAN. Compared with urea, SuperU reduced N2O-N emissions 48%, ESN 34%, Duration III 31%, UAN 27%, and UAN+AgrotainPlus 53% averaged over 2 yr. Compared with UAN, UAN+AgrotainPlus reduced N2O emissions 35% and SuperU 29% averaged over 2 yr. The N2O-N loss as a percentage of N applied was 0.3% for urea, with all other N sources having significantly lower losses. Grain production was not reduced by the use of alternative N sources. This work shows that enhanced-efficiency N fertilizers can potentially reduce N2O-N emissions without affecting yields from irrigated NT corn systems in the semiarid central Great Plains. PMID:21043261

  13. Nitrogen source effects on nitrous oxide emissions from irrigated no-till corn.

    PubMed

    Halvorson, Ardell D; Del Grosso, Stephen J; Francesco, Alluvione

    2010-01-01

    Nitrogen fertilization is essential for optimizing crop yields; however, it may potentially increase nitrous oxide (N2O) emissions. The study objective was to assess the ability of commercially available enhanced-efficiency N fertilizers to reduce N2O emissions following their application in comparison with conventional dry granular urea and liquid urea-ammonium nitrate (UAN) fertilizers in an irrigated no-till (NT) corn (Zea mays L.) production system. Four enhanced-efficiency fertilizers were evaluated: two polymer-coated urea products (ESN and Duration III) and two fertilizers containing nitrification and urease inhibitors (SuperU and UAN+AgrotainPlus). Nitrous oxide fluxes were measured during two growing seasons using static, vented chambers and a gas chromatograph analyzer. Enhanced-efficiency fertilizers significantly reduced growing-season N2O-N emissions in comparison with urea, including UAN. SuperU and UAN+AgrotainPlus had significantly lower N2O-N emissions than UAN. Compared with urea, SuperU reduced N2O-N emissions 48%, ESN 34%, Duration III 31%, UAN 27%, and UAN+AgrotainPlus 53% averaged over 2 yr. Compared with UAN, UAN+AgrotainPlus reduced N2O emissions 35% and SuperU 29% averaged over 2 yr. The N2O-N loss as a percentage of N applied was 0.3% for urea, with all other N sources having significantly lower losses. Grain production was not reduced by the use of alternative N sources. This work shows that enhanced-efficiency N fertilizers can potentially reduce N2O-N emissions without affecting yields from irrigated NT corn systems in the semiarid central Great Plains.

  14. N2O emission from nitrogen removal via nitrite in oxic-anoxic granular sludge sequencing batch reactor.

    PubMed

    Liang, Hong; Yang, Jiaoling; Gao, Dawen

    2014-03-01

    Bionitrification is considered to be a potential source of nitrous oxide (N2O) emissions, which are produced as a by-product during the nitrogen removal process. To investigate the production of N2O during the process of nitrogen removal via nitrite, a granular sludge was studied using a lab-scale sequence batch reactor operated with real-time control. The total production of N2O generated during the nitrification and denitrification processes were 1.724 mg/L and 0.125 mg/L, respectively, demonstrating that N2O is produced during both processes, with the nitrification phase generating larger amount. In addition, due to the N2O-N mass/oxidized ammonia mass ratio, it can be concluded that nitrite accumulation has a positive influence on N2O emissions. Results obtained from PCR-DGGE analysis demonstrate that a specific Nitrosomonas microorganism is related to N2O emission.

  15. 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.

  16. Spatial variability of nitrous oxide emissions and their soil-related determining factors in an agricultural field.

    PubMed

    Yanai, Junta; Sawamoto, Takuji; Oe, Taku; Kusa, Kanako; Yamakawa, Keisuke; Sakamoto, Kazunori; Naganawa, Takahiko; Inubushi, Kazuyuki; Hatano, Ryusuke; Kosaki, Takashi

    2003-01-01

    To evaluate spatial variability of nitrous oxide (N2O) emissions and to elucidate their determining factors on a field-scale basis, N2O fluxes and various soil properties were evaluated in a 100- x 100-m onion (Allium cepa L.) field. Nitrous oxide fluxes were determined by a closed chamber method from the one-hundred 10- x 10-m plots. Physical (e.g., bulk density and water content), chemical (e.g., total N and pH), and biological (e.g., microbial biomass C and N) properties were determined from surface soil samples (0-0.1 m) of each plot. Geostatistical analysis was performed to examine spatial variability of both N2O fluxes and soil properties. Multivariate analysis was also conducted to elucidate relationships between soil properties and observed fluxes. Nitrous oxide fluxes were highly variable (average 331 microg N m(-2) h(-1), CV 217%) and were log-normally distributed. Log-transformed N2O fluxes had moderate spatial dependence with a range of >75 m. High N2O fluxes were observed at sites with relatively low elevation. Multivariate analysis indicated that an organic matter factor and a pH factor of the principal component analysis were the main soil-related determining factors of log-transformed N2O fluxes. By combining multivariate analysis with geostatistics, a map of predicted N2O fluxes closely matched the spatial pattern of measured fluxes. The regression equation based on the soil properties explained 56% of the spatially structured variation of the log-transformed N2O fluxes. Site-specific management to regulate organic matter content and water status of a soil could be a promising means of reducing N2O emissions from agricultural fields. PMID:14674518

  17. Nitrous Oxide Emissions From a Maize/Soybean Rotation Following a Precipitation Event

    NASA Astrophysics Data System (ADS)

    Zheng, J.; Doskey, P. V.

    2011-12-01

    Agricultural soils are the largest anthropogenic source of nitrous oxide (N2O), which is one of the major greenhouse gases. Emissions of N2O from agricultural soils are highly episodic and primarily occur in pulses of emissions following fertilization, spring thaw, and precipitation events. Anaerobic denitrification is the major source of N2O emitted from agricultural soils. During denitrification, NO3- is converted to NO, N2O or N2 by a diverse group of microorganisms. Precipitation is an important environmental factor regulating N2O emissions as soil water filled pore space (WFPS) controls the diffusivity and solubility of O2 and N2O, and thus, enzyme affinity and activity of denitrifying microorganisms. The primary objective of the study is to investigate N2O emission patterns and possible mechanisms responsible for N2O emissions following precipitation events. We measured plot level N2O fluxes by the static chamber technique in- and between-the-row of young soybean at the AmeriFlux site in Bondville, Illinois following a precipitation event. Gas samples were taken 12 h before a heavy rainfall, and 6, 12 and 24 h after the rain. Two distinct pulses were observed following the rainfall. The first pulse occurred 6 h after the rain, with a 3-fold increase in the rate of N2O emissions (73.2 μg m-2 h-1) compared with emissions 12 h before the rain (24.0 μg m-2 h-1). The N2O emission rate decreased to 48.2 μg m-2 h-1 12 h after the rain. The second pulse was observed 24 h after the rain, with an emission rate of 63.1 μg m-2 h-1. Phospholipid fatty acids (PLFAs) were extracted from soil samples taken from corresponding plots to estimate the total living microbial biomass. There were no significant changes in total living microbial biomass (in ng PLFAs g-1 soil) between samples taken 12 h before the rain and 6 h after the rain, although microbial activity apparently increased. Increases in gram negative bacteria and fungi were observed 24 h after the rain. The first

  18. Influence of agricultural management on nitrous oxide emissions: comparison of different modelling approaches

    NASA Astrophysics Data System (ADS)

    Klier, C.; Gayler, S.; Haberbosch, C.; Ruser, R.; Stenger, R.; Flessa, H.; Priessack, E.

    2010-05-01

    Intensive agricultural land use is considered to be the major source of the anthropogenic contribution to the increase in atmospheric nitrous oxide (N2O) concentration during the last decades. Mathematical models help to understand interacting processes in the nitrogen cycle and state variables affecting N2O emissions. Most of the simulation models which have been used to estimate N2O emissions from soils under field conditions represent the underlying processes of denitrification or nitrification by first order rates without modelling the gaseous N2O transport process. In the first part of the study we compare two modelling approaches of the modular nitrogen modelling system Expert-N for their ability to describe and quantify the seasonal variations of N2O fluxes in a potato-cropped soil. Model 1 assumes a fixed N2O:N2 ratio for N2O production and neglects the transport of N2O in the soil profile, Model 2 explicitly considers a N2O transport and assumes a dynamic reduction of N2O to N2. Data for model evaluation arise from an experiment, where N2O fluxes were monitored over the vegetation period, using a closed chamber technique. Experimental results showed a variation of N and O2 supplies between the ridge soil and inter-row soil of the potato plantation and a corresponding impact on N2O release to atmosphere. Thus, in the second part of the study we applied a multiregion modelling approach to get a spatially explicit modelling tool. In the multiregion approach a heterogeneous soil hydraulic regime is subdivided into finite, multiple, hydraulically interacting regions in the form of soil columns. Modelling results showed for the first part of the study that both modelling approaches were able to describe the observed seasonal dynamics of N2O emissions and events of high N2O emissions due to increased denitrification activity after heavy precipitation and fertiliser application. Extremely high emission rates from the inter-row soil of the potato plantation were

  19. 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.

  20. 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

  1. 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

  2. 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

  3. 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.

  4. 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

    2016-01-01

    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. PMID:26848094

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    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.

  6. Nitrogen loading and nitrous oxide emissions from a river with multiple hydroelectric reservoirs.

    PubMed

    Chen, Jinsong; Cao, Wenzhi; Cao, Di; Huang, Zheng; Liang, Ying

    2015-05-01

    River networks receive a large fraction of the anthropogenic nitrogen applied to river catchments. The different impacts of the stream nitrogen (N) loading on nitrous oxide (N2O) emissions from various of aquatic ecosystems are still unknown. In this study, direct measurements of water-air interface N2O exchange in different water bodies were conducted. Results showed that the water-air interface N2O exchange from tributaries, hydropower station reservoirs, a main stream, and its estuary were 10.14 ± 13.51, 15.64 ± 10.72, 27.59 ± 20.99, and 15.98 ± 12.26 µg N2O-N m(-2) h(-1), respectively, indicating the strong impacts of human activities on N2O emission rates. The water NO2 (-)-N values predicted the dissolved N2O concentrations better than did the NO3 (-)-N and NH4 (+)-N values, indicating strong denitrification and nitrification processes. The dissolved inorganic N explained 36 % of the variations in the N2O emissions for the whole river network.

  7. 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.

  8. 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

    2016-01-01

    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.

  9. Biogeochemistry of Nitrous Oxide Production in the Red Mangrove ( Rhizophora mangle) Forest Sediments

    NASA Astrophysics Data System (ADS)

    Bauza, J. F.; Morell, J. M.; Corredor, J. E.

    2002-11-01

    This study was undertaken to quantify the emission and distribution of nitrous oxide and to explore its relation to pertinent physical and chemical parameters in a red mangrove forest located at Magueyes island, Puerto Rico. Rates of N2O evolution, which ranged from 0·05 to 1·4 μmole m-2 h-1 (overall mean=0·50 μmole m-2 h-1), are comparable to those of other previously studied ecosystems. A significant diel cycle of N2O emission was observed. Dissolved N2O concentration averaged 0·15 nmole cm-3 (SD=0·09, n=54) with a range of 0·1 to 0·57 nmole cm-3. Dissolved and exchangeable inorganic nitrogen was present mostly in the form of ammonium (overall mean=212·2 nmole cm-3) with lesser amounts of nitrate (overall mean=29·0 nmole cm-3). Redox potentials in the sediments generally decreased with depth, with a mean value of 377 mV at the sediment surfaces and lower mean value (159 mV) at 10 cm. We have explored the probable sources of N2O in the mangrove forest sediment using correlation analysis between the data obtained in this study and comparing these observations with previous studies of N2O metabolism. Our results, while not excluding the possibility of N2O production through denitrification, indicate that N2O is produced mainly by nitrification in sediments of this mangrove forest.

  10. 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.

  11. 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

  12. 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.

  13. Late Quaternary Variations of Atmospheric Nitrous Oxide Reconstructed from Polar Ice Cores

    NASA Astrophysics Data System (ADS)

    Schilt, A.; Baumgartner, M.; Blunier, T.; Schwander, J.; Spahni, R.; Fischer, H.; Stocker, T. F.

    2009-12-01

    Air extracted from polar ice cores offers the unique possibility to reconstruct the past composition of Earth’s atmosphere, and thus to study natural changes in biogeochemical cycles. Here, we present records of the greenhouse gas nitrous oxide (N2O) measured along the EPICA Dome C, EPICA Dronning Maud Land, Talos Dome and NGRIP ice cores. These records allow for the reconstruction of the N2O concentration during the interglacials of the last 800,000 years, while for most glacial time intervals an atmospheric record is missing due to insitu production of N2O in the ice. N2O which has both terrestrial and marine sources, varies in concert with Antarctic temperature during all interglacials back to Marine Isotope Stage 19. However, in contrast to carbon dioxide (CO2) and methane (CH4), N2O does not show lower concentrations in response to the lower temperature recorded for the interglacials between 800,000 and 440,000 years before present compared to the interglacials of the last 440,000 years. Also, N2O remains substantially longer at interglacial levels than CH4 at the end of most interglacials. On millennial time scales, N2O shows variations in concert with CH4 throughout the last 800,000 years. We suggest that these millennial-scale variations have been driven by a similar mechanism as the Dansgaard/Oeschger events known from the last glacial. We further establish a N2O composite record which covers, without gaps, more than one glacial-interglacial cycle, i.e. it reaches back to the beginning of the penultimate interglacial (Marine Isotope Stage 5.5) about 140,000 years ago. This composite record reveals substantial N2O variations in response to all Dansgaard/Oeschger events of the last glacial, and a N2O concentration of about 200 parts per billion by volume during the Last Glacial Maximum.

  14. The effects of season and agriculture on nitrous oxide production in headwater streams.

    PubMed

    Beaulieu, J J; Arango, C P; Tank, J L

    2009-01-01

    Streams and rivers are a globally significant source of nitrous oxide (N(2)O), a potent greenhouse gas. However, there remains much uncertainty in the magnitude of N(2)O emissions from these sources, partly due to an incomplete understanding of the factors that control microbial N(2)O production in lotic sediments. During 2004-2005 we measured sediment N(2)O production in 12 headwater streams across an agricultural land use gradient. Stream water nitrate (NO(3)(-)) concentrations were positively related to the proportion of agricultural land use in the basin and frequently exceeded 20 mg N L(-1) in the stream draining the most agricultural basin. Stream sediments were nearly always a net source of N(2)O, and production rates were positively related to stream water NO(3)(-) concentrations and sediment carbon content. There were no seasonal patterns in N(2)O production rates during 2004, but stream water NO(3)(-) and N(2)O production both peaked during the winter of 2005. The spike in NO(3)(-) concentrations likely resulted from winter rain and snowmelt that flushed NO(3)(-) from the soils following a dry summer and fall. In turn, the elevated stream water NO(3)(-) concentrations stimulated in-stream N(2)O production rates. Overall, we were only able to explain 29% of the variation in N(2)O production rates on a log scale. The unexplained variation may be due to differences in the fraction of denitrified NO(3)(-) that is converted to N(2)O among the study sites, or that our measures of substrate availability in the water column were not reflective of substrate availability in the porewater used by denitrifiers.

  15. An Improved Atmospheric Lifetime of Nitrous Oxide Based on Measurement and Constrained Models

    NASA Astrophysics Data System (ADS)

    DeLuca, N. M.; Prather, M. J.; Hsu, J. C.; Sovde, O. A.; Isaksen, I.; Jackman, C. H.; Fleming, E. L.; Douglass, A. R.; Strahan, S. E.; Steenrod, S. D.; Froidevaux, L.; Funke, B.

    2013-12-01

    Nitrous oxide (N2O) is an important part of our atmosphere's chemistry when considering both ozone depletion and the global climate. Long-lived atmospheric gasses like N2O have residence times of over a century, making anthropogenic perturbations in the present a lasting consequence. The study aims to calculate a best present-day atmospheric lifetime of N2O with uncertainty based on satellite observation and global chemistry transport models (CTMs). This revised lifetime needs to be considered in climate change assessments as it affects GWP values and projected N2O abundances. An observationally founded lifetime is first calculated using measurements from the NASA Aura satellite's Microwave Limb Sounder (MLS) instrument combined with two independent photochemical models including solar cycle effects. Four free-running CTMs are used to calculate both stratospheric N2O distributions and lifetimes. The MLS observations are compared to CTM tropical N2O distributions to identify model biases. Seasonal and interannual variations in N2O and NOy profiles that affect the N2O lifetime are assessed. The MLS data for N2O and O3 and the MIPAS satellite data for NOy are used as constraints to identify CTM biases that could influence their calculated lifetimes. This study finds that N2O lifetime fluctuates over a quasi-biennial cycle, and free-running CTMs can match this variability very well. The CTMs used here produce a wide range in lifetime, from 100 to more than 150 years, but the lifetime derived from the MLS data lies at the lower end, about 110 years.

  16. Effect of nitrous oxide on excitatory and inhibitory synaptic transmission in hippocampal cultures.

    PubMed

    Mennerick, S; Jevtovic-Todorovic, V; Todorovic, S M; Shen, W; Olney, J W; Zorumski, C F

    1998-12-01

    Nitrous oxide (N2O; laughing gas) has been a widely used anesthetic/analgesic since the 19th century, although its cellular mechanism of action is not understood. Here we characterize the effects of N2O on excitatory and inhibitory synaptic transmission in microcultures of rat hippocampal neurons, a preparation in which anesthetic effects on monosynaptic communication can be examined in a setting free of polysynaptic network variables. Eighty percent N2O occludes peak NMDA receptor-mediated (NMDAR) excitatory autaptic currents (EACs) with no effect on the NMDAR EAC decay time course. N2O also mildly depresses AMPA receptor-mediated (AMPAR) EACs. We find that N2O inhibits both NMDA and non-NMDA receptor-mediated responses to exogenous agonist. The postsynaptic blockade of NMDA receptors exhibits slight apparent voltage dependence, whereas the blockade of AMPA receptors is not voltage dependent. Although the degree of ketamine and Mg2+ blockade of NMDA-induced responses is dependent on permeant ion concentration, the degree of N2O blockade is not. We also observe a slight and variable prolongation of GABAA receptor-mediated (GABAR) postsynaptic currents likely caused by previously reported effects of N2O on GABAA receptors. Despite the effects of N2O on both NMDA and non-NMDA ionotropic receptors, glial glutamate transporter currents and metabotropic glutamate receptor-mediated synaptic depression are not affected. Paired-pulse depression, the frequency of spontaneous miniature excitatory synaptic currents, and high-voltage-activated calcium currents are not affected by N2O. Our results suggest that the effects of N2O on synaptic transmission are confined to postsynaptic targets. PMID:9822732

  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. Nitrous oxide in emergency medicine.

    PubMed

    O'Sullivan, I; Benger, J

    2003-05-01

    Safe and predictable analgesia is required for the potentially painful or uncomfortable procedures often undertaken in an emergency department. The characteristics of an ideal analgesic agent are safety, predictability, non-invasive delivery, freedom from side effects, simplicity of use, and a rapid onset and offset. Newer approaches have threatened the widespread use of nitrous oxide, but despite its long history this simple gas still has much to offer. "I am sure the air in heaven must be this wonder-working gas of delight". Robert Southey, Poet (1774 to 1843)

  19. 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.

  20. 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.

  1. 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

    2013-12-01

    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.

  2. 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.

  3. DNA damage induced by nitrous oxide: study in medical personnel of operating rooms.

    PubMed

    Wrońska-Nofer, Teresa; Palus, Jadwiga; Krajewski, Wojciech; Jajte, Jolanta; Kucharska, Małgorzata; Stetkiewicz, Jan; Wasowicz, Wojciech; Rydzyński, Konrad

    2009-06-18

    Occupational exposure to anaesthetics such as nitrous oxide (N(2)O) and halogenated hydrocarbons has been suggested to increase risk of genetic damage. However, the dose-dependency of genotoxic effects has not been unequivocally established and their relation to occupational exposure limit (OEL) remain obscure. In this study, the genotoxicity associated with occupational exposure to anaesthetics has been investigated in a group of 55 female nurses and 29 male anaesthesiologists active for at least 5 years in a working environment containing variable concentrations of N(2)O and halogenated hydrocarbons. 83 unexposed health care workers (52 female nurses and 31 male doctors) matched for age, gender, smoking habit and employment duration were included in the control group. Genotoxicity has been assessed using comet test. Concentrations of nitrous oxide, sevoflurane and isoflurane monitored by gas chromatography and mass spectrometry made possible to relate the extent of DNA damage to the level of exposure. Our results for the first time document a positive correlation between the DNA damage and the N(2)O levels in the ambient air. By contrast, no correlation has been observed between genotoxic effects and concentrations of sevoflurane and isoflurane. The extent of genetic injury was especially aggravated among nurses and anaesthesiologists exposed to N(2)O in concentrations exceeding OEL (180 mg/m(3)). We conclude that occupational exposure to N(2)O is associated with increased DNA damage and that the level of exposure plays a critical role in this regard. PMID:19439331

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

    PubMed

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

    2012-05-01

    Nitrous oxide (N(2)O) 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 (N(2)O) 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 N(2)O in oceans, soils and wastewaters, and discusses the genetic regulation and molecular details of the enzymes responsible. Techniques for providing global and local N(2)O budgets are discussed. The findings of the meeting are drawn together in a review of strategies for mitigating N(2)O emissions, under three headings, namely: (i) managing soil chemistry and microbiology, (ii) engineering crop plants to fix nitrogen, and (iii) sustainable agricultural intensification.

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

    PubMed Central

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

    2013-01-01

    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. PMID:24248380

  7. 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.

  8. Modelling nitrous oxide emissions from grazed grassland systems.

    PubMed

    Wang, Junye; Cardenas, Laura M; Misselbrook, Tom H; Cuttle, Steve; Thorman, Rachel E; Li, Changsheng

    2012-03-01

    Grazed grassland systems are an important component of the global carbon cycle and also influence global climate change through their emissions of nitrous oxide and methane. However, there are huge uncertainties and challenges in the development and parameterisation of process-based models for grazed grassland systems because of the wide diversity of vegetation and impacts of grazing animals. A process-based biogeochemistry model, DeNitrification-DeComposition (DNDC), has been modified to describe N(2)O emissions for the UK from regional conditions. This paper reports a new development of UK-DNDC in which the animal grazing practices were modified to track their contributions to the soil nitrogen (N) biogeochemistry. The new version of UK-DNDC was tested against datasets of N(2)O fluxes measured at three contrasting field sites. The results showed that the responses of the model to changes in grazing parameters were generally in agreement with observations, showing that N(2)O emissions increased as the grazing intensity increased.

  9. Gait abnormalities, ADHD, and environmental exposure to nitrous oxide.

    PubMed

    Fluegge, Keith

    2016-08-30

    Papadopoulos et al. (2014) investigated gait profiles of children with attention-deficit hyperactivity disorder-combined type (ADHD-CT) compared to typical developing (TD) controls. The authors reported differences in the gait profile of ADHD-CT in the self-selected fast speed category. Additionally, others have proposed a maturational delay hypothesis in gait, demonstrating that gait variability decreases with age in ADHD children. It has been previously suggested that the cognitive impairment seen in conditions like ADHD may result from chronic, environmental exposure to the air pollutant, nitrous oxide (N2O). Exposure to N2O is thought to exert its antinociceptive properties by stimulating release of dynorphin peptides in the central nervous system which act upon kappa opioid receptors (KOR). Opioid-mediated gait abnormalities in ADHD are supported with evidence that prodynorphin mutations in mice lead to cytotoxic levels of dynorphin A (DYN A) and contribute to abnormal gait profiles and gradual loss of motor coordination. Interestingly, constitutive activity of the KOR receptor in rat brain has been recently shown to undergo maturational alterations, suggesting that while altered gait profiles in ADHD may be a function of the enhanced opioidergic activity attributable to chronic exposure to the environmental air pollutant, N2O, age-attenuated constitutive activity of KOR in brain may explain the normalization of these altered gait profiles in older ADHD subjects. PMID:27285951

  10. 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.

  11. Production of Nitrous Oxide from Nitrite in Stable Type II Methanotrophic Enrichments.

    PubMed

    Myung, Jaewook; Wang, Zhiyue; Yuan, Tong; Zhang, Ping; Van Nostrand, Joy D; Zhou, Jizhong; Criddle, Craig S

    2015-09-15

    The coupled aerobic-anoxic nitrous decomposition operation is a new process for wastewater treatment that removes nitrogen from wastewater and recovers energy from the nitrogen in three steps: (1) NH4(+) oxidation to NO2(-), (2) NO2(-) reduction to N2O, and (3) N2O conversion to N2 with energy production. Here, we demonstrate that type II methanotrophic enrichments can mediate step two by coupling oxidation of poly(3-hydroxybutyrate) (P3HB) to NO2(-) reduction. Enrichments grown with NH4(+) and NO2(-) were subject to alternating 48-h aerobic and anoxic periods, in which CH4 and NO2(-) were added together in a "coupled" mode of operation or separately in a "decoupled mode". Community structure was stable in both modes and dominated by Methylocystis. In the coupled mode, production of P3HB and N2O was low. In the decoupled mode, significant P3HB was produced, and oxidation of P3HB drove reduction of NO2(-) to N2O with ∼ 70% conversion for >30 cycles (120 d). In batch tests of wasted cells from the decoupled mode, N2O production rates increased at low O2 or high NO2(-) levels. The results are significant for the development of engineered processes that remove nitrogen from wastewater and for understanding of conditions that favor environmental production of N2O.

  12. 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).

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

    DOE PAGES

    Tian, Hanqin; Chen, Guangsheng; Lu, Chaoqun; Xu, Xiaofeng; Ren, Wei; Zhang, Bowen; Banger, Kamaljit; Tao, Bo; Pan, Shufen; Chu, Mingliang; et al

    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.

  14. Heterogeneous Oxidation of Biomass Burning Aerosol Surrogates by O3, NO2, NO3, and N2O5

    NASA Astrophysics Data System (ADS)

    Knopf, D. A.; Slade, J. H.; Forrester, S.; Linville, D.

    2010-12-01

    Biomass burning is a major source of gases and particles to the atmosphere with a source strength of similar magnitude to fossil fuel burning. The particulate matter (PM) fraction of remote biomass burning events has been shown to significantly impact local air quality. Furthermore, biomass burning plumes can reach the upper troposphere and lower stratosphere (UT/LS). Consequently, biomass burning aerosol (BBA) can perturb atmospheric radiation directly through its effect on light extinction and indirectly by altering cloud properties. During transport, BBAs can react by gas-to-particle, termed heterogeneous, reactions with trace gases such as O3, NO2, NO3, and N2O5. It has been previously shown that high nighttime NO3, concentrations can render the NO3 radical a similar if not even more important oxidizer compared to OH. These oxidation reactions can result in the chemical transformation of the particles and thus significantly alter their physical and chemical properties. This in turn can have important implications for the particles’ role in cloud formation processes but will also impact the ability to apportion the source strength of BBAs if the molecular marker for biomass burning is altered during transport. Here we present a study employing a newly custom-built chemical ionization mass spectrometer coupled to a temperature-controlled rotating wall flow reactor to determine the heterogeneous kinetics between major organic compounds found in BBAs and O3, NO2, NO3. O3 is produced by passing O2 over an Hg lamp at 254 nm. N2O5 is produced by reacting an excess amount of O3 with NO2 and then stored at 193 K. NO3 is produced by thermal dissociation of N2O5. Detection of the reactant gases is achieved by using SF6- and I- as reagent ions. Our experimentally determined reactive uptake coefficients of O3, NO3, and N2O5 by oleic acid, and NO3 by unconjugated linoleic acid and n-hexadecane show agreement with previous studies. The major organic species determined in

  15. N2O - direct versus indirect effects on emissions

    NASA Astrophysics Data System (ADS)

    Zechmeister-Boltenstern, Sophie; Kitzler, Barbara

    2013-04-01

    The concentration of N2O in the atmosphere is much lower than that of CO2, but it is an important GHG because on an equivalent mass basis, N2O has c. 300 times the global warming potential of CO2. In addition to being a strong GHG, N2O is the primary stratospheric ozone depleting substance. The dominant sources of N2O are closely related to microbial production processes in soils, sediments and water bodies. Agricultural emissions due to N fertilizer use and manure management (4.3-5.8 Tg N2O-N yr-1) and emissions from natural soils (6-7 Tg N2O-N yr-1) are already representing 56-70% of all global N2O sources. The main agricultural sources of nitrous oxide include emissions from soils after application of inorganic and organic forms of nitrogen (N) as synthetic fertilizers, crop residues, manures or composts. Livestock operations also result in emissions from urine and faeces deposited on soils during grazing. In addition to the direct sources of N2O, there are also indirect ones that include N deposited onto land surfaces following ammonia and NOx volatilization, and nitrate leached from agricultural land in drainage water which, on passing into aquifers or into surface waters and their sediments, can be partially transformed to N2O (Smith et al., 2012). For inventories a default emission factor (EF) of 1.0 % of N fertilizer application has been fixed. The default indirect EFs are 1.0 % of N deposited from the atmosphere, and 0.75 % of N lost to watercourses by leaching or runoff. Depending on fertilizer type and environmental conditions field measurements reveal emission factors which deviate largely from the theoretical values. As soil moisture and temperature are major drivers of N2O emissions, warming and precipitation changes strongly affect the emission of N2O. More difficult is the prediction of climate extremes and their feedback on N2O which may occur via soil processes as well as limitations for plant growth and N uptake. Based on examples of recent

  16. 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. PMID:24781903

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. Lowering N2O emissions from soils using eucalypt biochar: the importance of redox reactions.

    PubMed

    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

  2. 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

  3. Nitrous oxide emission from highland winter wheat field after long-term fertilization

    NASA Astrophysics Data System (ADS)

    Wei, X. R.; Hao, M. D.; Xue, X. H.; Shi, P.; Horton, R.; Wang, A.; Zang, Y. F.

    2010-10-01

    Nitrous oxide (N2O) is an important greenhouse gas. N2O emissions from soils vary with fertilization and cropping practices. The response of N2O emission to fertilization of agricultural soils plays an important role in global N2O emission. The objective of this study was to assess the seasonal pattern of N2O fluxes and the annual N2O emissions from a rain-fed winter wheat (Triticum aestivum L.) field in the Loess Plateau of China. A static flux chamber method was used to measure soil N2O fluxes from 2006 to 2008. The study included 5 treatments with 3 replications in a randomized complete block design. Prior to initiating N2O measurements the treatments had received the same fertilization for 22 years. The fertilizer treatments were unfertilized control (CK), manure (M), nitrogen (N), nitrogen + phosphorus (NP), and nitrogen + phosphorus + manure (NPM). Soil N2O fluxes in the highland winter wheat field were highly variable temporally and thus were fertilization dependent. The highest fluxes occurred in the warmer and wetter seasons. Relative to CK, m slightly increased N2O flux while N, NP and NPM treatments significantly increased N2O fluxes. The fertilizer induced increase in N2O flux occurred mainly in the first 30 days after fertilization. The increases were smaller in the relatively warm and dry year than in the cold and wet year. Combining phosphorous and/or manure with mineral N fertilizer partly offset the nitrogen fertilizer induced increase in N2O flux. N2O fluxes at the seedling stage were mainly controlled by nitrogen fertilization, while fluxes at other plant growth stages were influenced by plant and environmental conditions. The cumulative N2O emissions were always higher in the fertilized treatments than in the non-fertilized treatment (CK). Mineral and manure nitrogen fertilizer enhanced N2O emissions in wetter years compared to dryer years. Phosphorous fertilizer offset 0.50 and 1.26 kg N2O-N ha-1 increases, while manure + phosphorous offset 0

  4. Nitrous oxide emission from highland winter wheat field after long-term fertilization

    NASA Astrophysics Data System (ADS)

    Wei, X. R.; Hao, M. D.; Xue, X. H.; Shi, P.; Wang, A.; Zang, Y. F.; Horton, R.

    2010-06-01

    Nitrous oxide (N2O) is an important greenhouse gas. N2O emissions from soils vary with fertilization and cropping practices. The response of N2O emission to fertilization of agricultural soils plays an important role in global N2O emission. The objective of this study was to assess the seasonal pattern of N2O fluxes and the annual N2O emissions from a rain-fed winter wheat (Triticum aestivum L.) field in the Loess Plateau of China. A static flux chamber method was used to measure soil N2O fluxes from 2006 to 2008. The study included 5 treatments with 3 replications in a randomized complete block design. Prior to initiating N2O measurements the treatments had received the same fertilization for 22 years. The fertilizer treatments were unfertilized control (CK), manure (M), nitrogen (N), nitrogen + phosphorus (NP), and nitrogen + phosphorus + manure (NPM). Soil N2O fluxes in the highland winter wheat field were highly variable temporally and thus were fertilization dependent. The highest fluxes occurred in the warmer and wetter seasons. Relative to CK, M slightly increased N2O flux while N, NP and NPM treatments significantly increased N2O fluxes. The fertilizer induced increase in N2O flux occurred mainly in the first 30 days after fertilization. The increases were smaller in the relatively warm and dry year than in the cold and wet year. Combining phosphorous and/or manure with mineral N fertilizer partly offset the nitrogen fertilizer induced increase in N2O flux. N2O fluxes at the seedling stage were mainly controlled by nitrogen fertilization, while fluxes at other plant growth stages were influenced by plant and environmental conditions. The cumulative N2O emissions were always higher in the fertilized treatments than in the non-fertilized treatment (CK). Mineral and manure nitrogen fertilizer enhanced N2O emissions in wetter years compared to dryer years. Phosphorous fertilizer offset 0.78 and 1.98 kg N2O ha-1 increases, while manure + phosphorous offset 0

  5. Nitrous oxide emissions from Chinese maize-wheat rotation systems: A 3-year field measurement

    NASA Astrophysics Data System (ADS)

    Cai, Yanjiang; Ding, Weixin; Luo, Jiafa

    2013-02-01

    Nitrous oxide (N2O) fluxes were measured over a 3-year period (2004-2007) in a long-term experimental field. The objectives of the study were to evaluate the interannual variation of N2O emissions from a maize-wheat rotation, under different fertilizer regimes and to determine the key controlling factors. The study involved four treatments: compost (OM), half compost N plus half inorganic fertilizer-N (HOM), inorganic fertilizer-N (NPK), and control (CK) where no N application. The mean annual N2O emission over a 3-year period was 0.30 ± 0.11 kg N2O-N ha-1 in the CK treatment, but increased to 1.61 ± 0.10 kg N2O-N ha-1 in the HOM treatment, 2.13 ± 0.15 kg N2O-N ha-1 in the OM treatment, and 2.76 ± 0.19 kg N2O-N ha-1 in the NPK treatment. Differences were significant among treatments. The N2O emission factors of the applied OM, NPK and HOM were 0.61 ± 0.02, 0.82 ± 0.10 and 0.44 ± 0.04%, respectively, at a rate of 300 kg N ha-1 year-1, indicating that the combined application of compost with inorganic fertilizer significantly reduced N2O emission. Over a maize-wheat rotation year, more than 65% of the annual N2O emission occurred during the maize growing season. There was a large interannual variation in N2O emission in all treatments, albeit not significant either during the maize growing season or at an inter-year scale. This interannual variation was mainly attributable to differences in soil moisture after basal fertilizer application, and irrigation and/or heavy rainfall events immediately following basal fertilization could induce more N2O production than pre-irrigation before plowing. The HOM treatment had higher N fertilizer use efficiency and lowest yield-scaled N2O emissions compared with the OM and NPK treatments. We therefore argue that the combined application of half compost N plus half fertilizer-N will mitigate N2O emissions from soils in the North China plain.

  6. 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.

  7. 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.

  8. 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. PMID:23440192

  9. Abundance, transcription levels and phylogeny of bacteria capable of nitrous oxide reduction in a municipal wastewater treatment plant.

    PubMed

    Song, Kang; Suenaga, Toshikazu; Hamamoto, Aki; Satou, Kouichi; Riya, Shohei; Hosomi, Masaaki; Terada, Akihiko

    2014-09-01

    Nitrous oxide (N2O) production and expression of genes capable of its reduction were investigated in two full-scale parallel plug-flow activated sludge systems. These two systems continuously received wastewater with the same constituents, but operated under distinct nitrification efficiencies due to mixed liquor suspended solid (MLSS) concentration and the different hydraulic retention times (HRTs). A shorter HRT in system 2 resulted in a lower nitrification efficiency (40-60%) in conjunction with a high N2O emission (50.6 mg-N/L/day), whereas there was a higher nitrification efficiency (>99%) in system 1 with low N2O emission (22.6 mg-N/L/day). The DNA abundance of functional genes responsible for nitrification and denitrification were comparable in both systems, but transcription of nosZ mRNA in the lower N2O emission system (system 1) was one order of magnitude higher than that in the higher N2O emission system (system 2). The diversity and evenness of the nosZ gene were nearly identical; however, the predominant N2O reducing bacteria were phylogenetically distinct. Phylogenetic analysis indicated that N2O-reducing strains only retrieved in system 1 were close to the genera Rhodobacter, Oligotropha and Shinella, whereas they were close to the genera Mesorhizobium only in system 2. The distinct predominant N2O reducers may directly or indirectly influence N2O emissions.

  10. Coexistence of nitrous oxide undersaturation and oversaturation in the surface and subsurface of the western Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Zhang, Jiexia; Zhan, Liyang; Chen, Liqi; Li, Yuhong; Chen, Jianfang

    2015-12-01

    The nitrous oxide (N2O) distributions in a shelf-slope-basin section from the Chukchi Sea shelf to the Chukchi Abyssal Plain (CAP) in the western Arctic Ocean were observed for the first time during the fourth Chinese National Arctic Research Expedition (4th CHINARE) in late August 2010. The N2O concentrations were 11.4-16.9 nmol L-1, corresponding to saturation values of 92-118% in the surface water. In the surface, biological factor was negligible to N2O production, and physical process dominated the surface N2O distribution. The N2O undersaturation may be the result of dilution by sea ice meltwater. The oversaturation may be caused by the diffusing of N2O-rich shelf bottom water. Below the surface, N2O concentrations ranged from 11.4 to 21.4 nmol L-1. On the Chukchi Sea shelf, N2O concentrations increased from the surface to the near-bottom water, indicating sediment N2O produced by nitrification or denitrification emission may be a significant source. The subsurface maxima in the upper halocline layer (UHL) may receive partial contribution from nitrification production but was primarily caused by the spreading of shelf water.

  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. 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.

  13. Abundance, transcription levels and phylogeny of bacteria capable of nitrous oxide reduction in a municipal wastewater treatment plant.

    PubMed

    Song, Kang; Suenaga, Toshikazu; Hamamoto, Aki; Satou, Kouichi; Riya, Shohei; Hosomi, Masaaki; Terada, Akihiko

    2014-09-01

    Nitrous oxide (N2O) production and expression of genes capable of its reduction were investigated in two full-scale parallel plug-flow activated sludge systems. These two systems continuously received wastewater with the same constituents, but operated under distinct nitrification efficiencies due to mixed liquor suspended solid (MLSS) concentration and the different hydraulic retention times (HRTs). A shorter HRT in system 2 resulted in a lower nitrification efficiency (40-60%) in conjunction with a high N2O emission (50.6 mg-N/L/day), whereas there was a higher nitrification efficiency (>99%) in system 1 with low N2O emission (22.6 mg-N/L/day). The DNA abundance of functional genes responsible for nitrification and denitrification were comparable in both systems, but transcription of nosZ mRNA in the lower N2O emission system (system 1) was one order of magnitude higher than that in the higher N2O emission system (system 2). The diversity and evenness of the nosZ gene were nearly identical; however, the predominant N2O reducing bacteria were phylogenetically distinct. Phylogenetic analysis indicated that N2O-reducing strains only retrieved in system 1 were close to the genera Rhodobacter, Oligotropha and Shinella, whereas they were close to the genera Mesorhizobium only in system 2. The distinct predominant N2O reducers may directly or indirectly influence N2O emissions. PMID:24725963

  14. 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

  15. 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.

  16. 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.

  17. Nitrous oxide emission and denitrification in chronically nitrate-loaded riparian buffer zones.

    PubMed

    Hefting, Mariet M; Bobbink, Roland; de Caluwe, Hannie

    2003-01-01

    Riparian buffer zones are known to reduce diffuse N pollution of streams by removing and modifying N from agricultural runoff. Denitrification, often identified as the key N removal process, is also considered as a major source of the greenhouse gas nitrous oxide (N2O). The risks of high N2O emissions during nitrate mitigation and the environmental controls of emissions have been examined in relatively few riparian zones and the interactions between controls and emissions are still poorly understood. Our objectives were to assess the rates of N2O emission from riparian buffer zones that receive large loads of nitrate, and to evaluate various factors that are purported to control N emissions. Denitrification, nitrification, and N2O emissions were measured seasonally in grassland and forested buffer zones along first-order streams in The Netherlands. Lateral nitrate loading rates were high, up to 470 g N m(-2) yr(-1). Nitrogen process rates were determined using flux chamber measurements and incubation experiments. Nitrous oxide emissions were found to be significantly higher in the forested (20 kg N ha(-1) yr(-1)) compared with the grassland buffer zone (2-4 kg N ha(-1) yr(-1)), whereas denitrification rates were not significantly different. Higher rates of N2O emissions in the forested buffer zone were associated with higher nitrate concentrations in the ground water. We conclude that N transformation by nitrate-loaded buffer zones results in a significant increase of greenhouse gas emission. Considerable N2O fluxes measured in this study indicate that Intergovernmental Panel on Climate Change methodologies for quantifying indirect N2O emissions have to distinguish between agricultural uplands and riparian buffer zones in landscapes receiving large N inputs. PMID:12931872

  18. Nitrous Oxide Emissions from Riparian Forest Buffers, Warm-Season and Cool-Season Grass Filters, and Crop Fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increasing denitrification rates in riparian buffers may be trading the problem of nonpoint source (NPS) pollution of surface waters for atmospheric deterioration and increased global warming potential because denitrification produces nitrous oxide (N2O), a greenhouse gas also involved in stratosphe...

  19. 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...

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. Exploring the Potential of an Isotopic N2O Analyzer to Observe Soil Biogeochemical Processes in Real-time

    NASA Astrophysics Data System (ADS)

    Jorgensen, R.; Koyama, A.; von Fischer, J. C.; Gupta, M.

    2012-12-01

    We evaluated the potential applications of an Isotopic Nitrous Oxide (N2O) Analyzer (Los Gatos Research), which can measure isotopic values of N2O (δ15Nα, δ15Nβ, δ15N and δ18O) as well as [N2O] at real-time. The analyzer can provide continuous and precise measurements of the isotopic values with a quantum cascade laser along with cavity enhanced laser absorption spectroscopy technique. We evaluated the analyzer by quantifying N2O produced from soils and sediments, N2O dissolved in water, and a N2O standard for δ15N and δ18O. In quantifying N2O production from soils, we used four soils collected from diverse grassland sites across the North American Great Plains. In this lobe of the study, we investigated the relationship between N2O production rates and soil water content (SWC) by manipulating soil water levels in a lab setting. We hypothesized that N2O production rates would be positively correlated with SWC because we expected denitrification to be a more important N2O source than nitrification. Consistent with this hypothesis, we observed that soils adjusted at high SWC (20 to 50%) produced significant N2O. Parallel experiments using 15N labeling (15NH4+ and 15NO3-) suggested that N2O from the soils with high SWC was produced mostly via denitrification. Most of the soils adjusted with low SWC (10 to 20%) produced little N2O. When we observed measurable N2O from one soil with low SWC, the 15N labeling experiment suggested that N2O was produced via nitrification. Our measurements demonstrate that the Isotopic N2O Analyzer can be a powerful tool to investigate N2O dynamics in various materials, such as soils and water, in different environmental settings.

  5. 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

  6. 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. PMID:26812575

  7. 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.

  8. Nitrous oxide fluxes in an ecosystem context

    NASA Astrophysics Data System (ADS)

    Groffman, P. M.; Burgin, A. J.; Morse, J. L.

    2011-12-01

    Nitrous oxide fluxes are extremely difficult to quantify because this gas is produced by multiple processes that have complex controls that vary in time and space. Fluxes often exhibit extraordinary variability, with activity dominated by brief periods (hot moments) and small areas (hotspots) of flux. One approach to evaluating nitrous oxide is to focus on how flux is linked to overall patterns of nitrogen cycling in an ecosystem which can point to potential hotspots and hot moments that be incorporated into sampling campaigns. A key impediment to this approach, has been an inability to quantify the ratio of nitrous oxide to dinitrogen produced during dissimilatory processes, especially denitrification. Here we present data on nitrous oxide and dinitrogen fluxes from watershed/landscape studies at National Science Foundation funded Long Term Ecological Research (LTER) sites in Maryland (Baltimore LTER) and New Hampshire (Hubbard Brook LTER). Fluxes were measured using a new direct flow soil core incubation system that allows for quantification of the nitrous oxide yield during denitrification and the watershed/landscape studies provide data on overall ecosystem nitrogen cycling. Results suggest that nitrous oxide flux and yield vary coherently with spatial and temporal patterns of ecosystem nitrogen cycling. These patterns should allow us to develop more focused measurement and modeling campaigns that should result in improved understanding and estimates of nitrous oxide fluxes from forest ecosystems.

  9. 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.

  10. 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">

  11. 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.

  12. 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.

  13. 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.

  14. Methane and nitrous oxide emissions from a subtropical coastal embayment (Moreton Bay, Australia).

    PubMed

    Musenze, Ronald S; Werner, Ursula; Grinham, Alistair; Udy, James; Yuan, Zhiguo

    2015-03-01

    Surface water methane (CH4) and nitrous oxide (N2O) concentrations and fluxes were investigated in two subtropical coastal embayments (Bramble Bay and Deception Bay, which are part of the greater Moreton Bay, Australia). Measurements were done at 23 stations in seven campaigns covering different seasons during 2010-2012. Water-air fluxes were estimated using the Thin Boundary Layer approach with a combination of wind and currents-based models for the estimation of the gas transfer velocities. The two bays were strong sources of both CH4 and N2O with no significant differences in the degree of saturation of both gases between them during all measurement campaigns. Both CH4 and N2O concentrations had strong temporal but minimal spatial variability in both bays. During the seven seasons, CH4 varied between 500% and 4000% saturation while N2O varied between 128 and 255% in the two bays. Average seasonal CH4 fluxes for the two bays varied between 0.5±0.2 and 6.0±1.5 mg CH4/(m2·day) while N2O varied between 0.4±0.1 and 1.6±0.6 mg N2O/(m2·day). Weighted emissions (t CO2-e) were 63%-90% N2O dominated implying that a reduction in N2O inputs and/or nitrogen availability in the bays may significantly reduce the bays' greenhouse gas (GHG) budget. Emissions data for tropical and subtropical systems is still scarce. This work found subtropical bays to be significant aquatic sources of both CH4 and N2O and puts the estimated fluxes into the global context with measurements done from other climatic regions. PMID:25766016

  15. Nitrous oxide fluxes from the littoral zone of a lake on the Qinghai-Tibetan Plateau.

    PubMed

    Chen, Huai; Wang, Meng; Wu, Ning; Wang, Yanfen; Zhu, Dan; Gao, Yongheng; Peng, Changhui

    2011-11-01

    Nitrous oxide (N(2)O) fluxes were measured in six littoral mirco-zones of Lake Huahu on Qinghai-Tibetan Plateau in the peak growing season of years of 2006 and 2007. The weighted mean N(2)O flux rate was 0.08 mg N m(-2) h(-1) (ranged from -0.07 to 0.35 mg N m(-2) h(-1)). The result was relatively high in the scope of N(2)O fluxes from boreal and temperate lakes. Emergent plant zones (Hippuris vulgaris and Glyceria maxima stands) recorded the highest N(2)O flux rate (0.11 ± 0.24 and 0.08 ± 0.17 mg N m(-2) h(-1), respectively). Non-vegetated lakeshore recorded the lowest N(2)O flux (0.03 ± 0.11 mg N m(-2) h(-1)), lower than that from the floating mat zone of Carex muliensis (0.05 ± 0.18 mg N m(-2) h(-1)), the floating-leaved plant zone of Polygonum amphibium (0.07 ± 0.11 mg N m(-2) h(-1)), and the wet meadow (0.07 ± 0.15 mg N m(-2) h(-1)). Standing water depths were important factors to explain such spatial variations in N(2)O fluxes. Significant temporal variations in N(2)O fluxes were also found. Such temporal variation in N(2)O flux in the littoral zone may be dependent on the interaction of water regime and thermal conditions, instead of the latter solely. These results showed the importance of the littoral zone of lake, especially the emergent plant zone, as a hotspot of N(2)O fluxes in such grazing meadows.

  16. 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 we