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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. Diurnality of soil nitrous oxide (N2O) emissions

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  4. 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

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

    PubMed

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

    2015-01-01

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

  6. 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.

  7. 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

  8. 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

  9. Nitrous oxide (N2O) emissions from biotrickling filters used for ammonia removal at livestock facilities.

    PubMed

    Melse, Roland W; Mosquera, Julio

    2014-01-01

    Recently several manufacturers of nitrifying biotrickling filters for ammonia (NH3) removal at animal houses have started to add a denitrification step to the installation, aiming to reduce the amount of discharge water by conversion of NH3 to nitrogen gas (N2). The aim of this research was to quantify the possible formation of nitrous oxide (N2O), which is a potent greenhouse gas, in three of these farm-scale installations. Furthermore, the removal efficiency of NH3 and odor was determined. All installations were successful in reducing the amount of discharge water. The average NH3 removal efficiency for the three locations was 85, 71 and 86%, respectively. However, a significant part of the NH3 removed from the inlet air was not converted to N2 but to N2O, which is a potent greenhouse gas. The part of the inlet NH3-N that was converted to N2O-N amounted to 17, 66 and 24%, respectively. The high N2O production might have been caused by a too low scarcity of biodegradable carbon/N ratio for complete denitrification. The average odor removal efficiency was 21, 32 and 48%, respectively. Further research is necessary to explore how process conditions can be adjusted and controlled in order to reduce the production and emission of N2O from these types of systems. PMID:24622548

  10. 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.

  11. 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

  12. 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.

  13. 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

  14. 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

  15. 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. PMID:25450644

  16. 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. PMID:24927583

  17. Effect of aeration on nitrous oxide (N2O) emission from nitrogen-removing sequencing batch reactors.

    PubMed

    Kim, Dong-Jin; Kim, Yuri

    2013-01-01

    In this study, nitrous oxide (N(2)O) emission was compared between the operations of two different sequencing batch reactors, conventional sequencing batch reactor (CNVSBR) and simultaneous nitrification and denitrification sequencing batch reactor (SND-SBR), using synthetic wastewater. The CNV-SBR consisted of anoxic (denitrification) and aerobic phases, whereas the SND-SBR consisted of a microaerobic (low dissolved oxygen concentration) phase, which was achieved by intermittent aeration for simultaneous nitrification and denitrification. The CNV-SBR emitted 3.9 mg of N(2)O-N in the denitrification phase and 1.6 mg of N2O-N in the nitrification phase, resulting in a total emission of 5.5 mg from 432 mg of NH(4)(+)-N input. In contrast, the SND-SBR emitted 26.2 mg of N(2)O-N under the microaerobic condition, which was about 5 times higher than the emission obtained with the CNV-SBR at the same NH(4)(+)-N input. From the N(2)O yield based on NH(4)(+)-N input, the microaerobic condition produced the highest yield (6.1%), followed by the anoxic (0.9%) and aerobic (0.4%) conditions. It is thought that an appropriate dissolved oxygen level is critical for reducing N(2)O emission during nitrification and denitrification at wastewater treatment plants. PMID:23314375

  18. Investigating the Mechanism for the Formation of Nitrous Oxide [N2O(X 1Σ+)] in Extraterrestrial Ices

    NASA Astrophysics Data System (ADS)

    Jamieson, Corey S.; Bennett, Chris J.; Mebel, Alexander M.; Kaiser, Ralf I.

    2005-05-01

    The formation of nitrous oxide, N2O(X 1Σ+), in interstellar space and in ices on Pluto and Triton has been experimentally investigated. A molecular nitrogen (N2) and carbon dioxide (CO2) ice mixture was irradiated at 10 K with 5 keV electrons to simulate the electronic interaction effects of Galactic cosmic-ray bombardment of extraterrestrial ice samples over a time of 5×106 yr. By monitoring the experiment with a Fourier transform infrared spectrometer on line and in situ, the temporal evolution of the 2235 cm-1 absorption band of nitrous oxide was found to follow pseudo-first-order kinetics. This indicates that the mechanism of formation is most likely a reaction between ground-state molecular nitrogen, N2(X 1Σ+g), and an oxygen atom, either in the ground state (3P) or in the first electronically excited state (1D), within the matrix cage through an addition of the oxygen atom to a nonbonding electron pair on the nitrogen molecule. The observation of nitrous oxide together with the kinetics and dynamics studies investigated in this paper underline the role of nonequilibrium processes in low-temperature ice matrices, aid in the understanding of chemical reaction pathways that exist in extraterrestrial ices, and assist a prospective identification of nitrous oxide on the surfaces of Pluto and Triton.

  19. 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. PMID:26841778

  20. 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.

  1. 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

  2. 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

  3. 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.

  4. 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

  5. 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

  6. 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.

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

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 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 PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Manure...

  8. 40 CFR Table Jj-7 to Subpart Jj of... - Nitrous Oxide Emission Factors (kg N2O-N/kg Kjdl N)

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Nitrous Oxide Emission Factors (kg N2O-N/kg Kjdl N) JJ Table JJ-7 to Subpart JJ of Part 98 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Manure...

  9. 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 PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Manure...

  10. 40 CFR Table Jj-7 to Subpart Jj of... - Nitrous Oxide Emission Factors (kg N2O-N/kg Kjdl N)

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 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 PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Manure...

  11. 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

  12. Revisiting the catalytic CuZ cluster of nitrous oxide (N2O) reductase. Evidence of a bridging inorganic sulfur.

    PubMed

    Brown, K; Djinovic-Carugo, K; Haltia, T; Cabrito, I; Saraste, M; Moura, J J; Moura, I; Tegoni, M; Cambillau, C

    2000-12-29

    Nitrous-oxide reductases (N2OR) catalyze the two-electron reduction of N(2)O to N(2). The crystal structure of N2ORs from Pseudomonas nautica (Pn) and Paracoccus denitrificans (Pd) were solved at resolutions of 2.4 and 1.6 A, respectively. The Pn N2OR structure revealed that the catalytic CuZ center belongs to a new type of metal cluster in which four copper ions are liganded by seven histidine residues. A bridging oxygen moiety and two other hydroxide ligands were proposed to complete the ligation scheme (Brown, K., Tegoni, M., Prudencio, M., Pereira, A. S., Besson, S., Moura, J. J. G., Moura, I., and Cambillau, C. (2000) Nat. Struct. Biol. 7, 191-195). However, in the CuZ cluster, inorganic sulfur chemical determination and the high resolution structure of Pd N2OR identified a bridging inorganic sulfur instead of an oxygen. This result reconciles the novel CuZ cluster with the hitherto puzzling spectroscopic data. PMID:11024061

  13. 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

  14. 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

  15. 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

  16. 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

  17. Spatial variability of nitrous oxide and methane emissions from an MBT landfill in operation: strong N2O hotspots at the working face.

    PubMed

    Harborth, Peter; Fuss, Roland; Münnich, Kai; Flessa, Heinz; Fricke, Klaus

    2013-10-01

    Mechanical biological treatment (MBT) is an effective technique, which removes organic carbon from municipal solid waste (MSW) prior to deposition. Thereby, methane (CH4) production in the landfill is strongly mitigated. However, direct measurements of greenhouse gas emissions from full-scale MBT landfills have not been conducted so far. Thus, CH4 and nitrous oxide (N2O) emissions from a German MBT landfill in operation as well as their concentrations in the landfill gas (LFG) were measured. High N2O emissions of 20-200gCO2eq.m(-2)h(-1) magnitude (up to 428mgNm(-2)h(-1)) were observed within 20m of the working face. CH4 emissions were highest at the landfill zone located at a distance of 30-40m from the working face, where they reached about 10gCO2eq.m(-2)h(-1). The MBT material in this area has been deposited several weeks earlier. Maximum LFG concentration for N2O was 24.000ppmv in material below the emission hotspot. At a depth of 50cm from the landfill surface a strong negative correlation between N2O and CH4 concentrations was observed. From this and from the distribution pattern of extractable ammonium, nitrite, and nitrate it has been concluded that strong N2O production is associated with nitrification activity and the occurrence of nitrite and nitrate, which is initiated by oxygen input during waste deposition. Therefore, CH4 mitigation measures, which often employ aeration, could result in a net increase of GHG emissions due to increased N2O emissions, especially at MBT landfills. PMID:23453435

  18. Seasonal, inter-annual and decadal changes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) in the Scheldt estuary (Belgium, The Netherlands)

    NASA Astrophysics Data System (ADS)

    Borges, Alberto V.; Middelburg, Jack J. B.; Chou, Lei; Kromkamp, Jacco; Houtekamer, Marco; Harlay, Jérôme

    2014-05-01

    We carried out monthly cruises to study the seasonal and spatial variations of the partial pressure of carbon dioxide CO2 (pCO2), methane (CH4) and nitrous oxide (N2O) concentrations in the Scheldt estuary, a strongly human impacted system located in Belgium and the Netherlands. This survey was initiated in 2008 for pCO2, and from 2009 onwards for methane (CH4) and nitrous oxide (N2O). In the lower estuary, pCO2 strongly decreased and oxygen saturation level (%O2) strongly increased during the spring phytoplankton bloom. In the upper estuary, two yearly maxima of pCO2 coinciding with minima of %O2 occurred in spring and fall due to enhanced nitrification and/or net heterotrophy. In the upper estuary, pCO2 decreased in winter due to lower temperature (affecting solubility and inhibiting biological activity). pCO2 also decreased in summer due to increase in primary production and decrease of net heterotrophy. In the upper estuary, maxima of CH4 were observed in winter due to enhanced river inputs (high discharge) while in the lower estuary higher CH4 was observed in summer. This was probably due to inputs of CH4 from inter-tidal areas at the mouth of estuary that increased in summer due to higher temperatures and higher organic matter availability. N2O also showed higher values during winter in the upper estuary, but in summer N2O was low in the lower estuary due to decreased solubility due to higher temperature. During winter 2009, extremely high N2O values were observed in the upper estuary, up to 3257 nM (23738% saturation). This was related to the problems encountered by the Brussels North waste water treatment plant (WWTP) in late 2009. One of the collectors of the station was shut down in 25 November 2009, and by 8 December 2009, the whole WWTP was shut down and the waste-water was delivered directly to the Rupel. Extremely high N2O values were observed in the upper estuary on 7 December 2009, and abnormally high N2O values (compared to other years) persisted

  19. 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. PMID:19713491

  20. A new CuZ active form in the catalytic reduction of N(2)O by nitrous oxide reductase from Pseudomonas nautica.

    PubMed

    Dell'Acqua, Simone; Pauleta, Sofia R; Paes de Sousa, Patrícia M; Monzani, Enrico; Casella, Luigi; Moura, José J G; Moura, Isabel

    2010-08-01

    The final step of bacterial denitrification, the two-electron reduction of N(2)O to N(2), is catalyzed by a multi-copper enzyme named nitrous oxide reductase. The catalytic centre of this enzyme is a tetranuclear copper site called CuZ, unique in biological systems. The in vitro reconstruction of the activity requires a slow activation in the presence of the artificial electron donor, reduced methyl viologen, necessary to reduce CuZ from the resting non-active state (1Cu(II)/3Cu(I)) to the fully reduced state (4Cu(I)), in contrast to the turnover cycle, which is very fast. In the present work, the direct reaction of the activated form of Pseudomonas nautica nitrous oxide reductase with stoichiometric amounts of N(2)O allowed the identification of a new reactive intermediate of the catalytic centre, CuZ degrees , in the turnover cycle, characterized by an intense absorption band at 680 nm. Moreover, the first mediated electrochemical study of Ps. nautica nitrous oxide reductase with its physiological electron donor, cytochrome c-552, was performed. The intermolecular electron transfer was analysed by cyclic voltammetry, under catalytic conditions, and a second-order rate constant of (5.5 +/- 0.9) x 10(5) M(-1 )s(-1) was determined. Both the reaction of stoichiometric amounts of substrate and the electrochemical studies show that the active CuZ degrees species, generated in the absence of reductants, can rearrange to the resting non-active CuZ state. In this light, new aspects of the catalytic and activation/inactivation mechanism of the enzyme are discussed. PMID:20422435

  1. 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.

  2. 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.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

    Lebegue, B.; Schmidt, M.; Ramonet, M.; Wastine, B.; Yver Kwok, C.; Laurent, O.; Belviso, S.; Guemri, A.; Philippon, C.; Smith, J.; Conil, S.; Jost, H. J.; Crosson, E. R.

    2015-10-01

    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 (ECDs). When trying to meet the World Meteorological Organization's (WMO) quality goal, this technique becomes very challenging as the detectors are highly non-linear 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 more robust optical spectrometers being 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 tested seven analyzers that were developed and commercialized from five different companies and compared the results with established techniques. Each instrument was characterized during a time period of approximately eight 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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  6. 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

  7. 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.

  8. 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

  9. 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

  10. 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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  12. 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

  13. 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.

  14. 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

  15. 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...

  16. 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...

  17. 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.

  18. 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.

  19. 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.

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

    PubMed

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

    2015-01-01

    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

  1. 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.

  2. 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

  3. 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...

  4. Nitrogen Source Effects on Nitrous Oxide Emissions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effects of N fertilizer source and tillage on nitrous oxide (N2O) emissions from soils under several irrigated, crop management systems were evaluated. Irrigated corn production systems [conventional-till continuous corn (CT-CC); no-till continuous corn (NT-CC); NT corn-dry bean (NT-CDb); and NT cor...

  5. 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

  6. Photolytic Fractionation of Stratospheric Nitrous Oxide

    NASA Astrophysics Data System (ADS)

    Blake, G. A.; Liang, M.; Morgan, C. G.

    2002-05-01

    The isotopically light N2O produced by microbial activity is known to be balanced by the return of heavy stratospheric nitrous oxide. Present atmospheric models predict fractionation factors approximately half those observed, however, leaving open the possibility that unknown processes generate substantial quantities of isotopically enriched nitrous oxide. Here we present a rigorous Born-Oppenheimer analysis of the wavelength-dependent N2O photolytic fractionation and incorporate the resulting fractionation factors into two-dimensional simulations of the stratosphere. Excellent agreement is found between predictions and laboratory/stratospheric measurements, and implies that our understanding of the photochemical cycling of this important trace gas is sufficiently complete to permit quantitative determinations of the natural and anthropogenic sources of N2O using their isotopic signatures.

  7. Effects of nitrogen fertilizer types on nitrous oxide emissions

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  8. 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 ...

  9. Modeling nitrous oxide emissions from bioenergy cropping systems using DAYCENT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) is the largest greenhouse gas source from crop systems and quantifying it for the U.S. Greenhouse Gas Inventory is important. The objective of this study was to validate the ability of DAYCENT to simulate N2O emissions from bioenergy cropping systems. From weather, soil-texture c...

  10. 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...

  11. 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...

  12. Nitrous Oxide Emissions from Irrigated Cropping Systems in Colorado

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Little information is available on the effects of irrigated crop management practices on nitrous oxide (N2O) emissions. Nitrous oxide emissions were monitored from irrigated cropping systems receiving N fertilizer rates ranging from 0 to 246 kg N ha-1 during the 2005 and 2006 growing seasons. Cro...

  13. 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

  14. Nitrogen Source and Placement Affect Soil Nitrous Oxide Emissions from Irrigated Corn in Colorado

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Limited information is available on the effects of N fertilizer source on soil nitrous oxide (N2O) emissions. This article summarizes research conducted by the USDA-ARS from 2009-2011 on N fertilizer source effects on growing season soil nitrous oxide (N2O) emissions from irrigated corn systems in...

  15. 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

  16. 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

  17. 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.

  18. Nitrous oxide emission by aquatic macrofauna

    PubMed Central

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

    2009-01-01

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

  19. 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...

  20. Split application of urea does not decrease and may increase nitrous oxide emissions in rainfed corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Modification of nitrogen (N) fertilizer application timing within the growing season has the potential to reduce soil nitrous oxide (N2O) emissions but limited data are available to assess its effects. We compared cumulative growing season N2O emissions (cN2O) following urea applied to corn (Zea may...

  1. 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...

  2. ON-LINE MEASUREMENT OF NITROUS OXIDE FROM COMBUSTION SOURCES BY AUTOMATED GAS CHROMATOGRAPHY

    EPA Science Inventory

    The paper discusses on-line measurement of nitrous oxide (N2O) from combustion sources by automated gas chromatography. ossil fuel combustion is suspected of contributing to measured increases in the ambient concentrations of N2O. haracterization of N2O emissions from fossil fuel...

  3. 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...

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

    PubMed

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

    2014-08-01

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

  5. 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

  6. 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

  7. 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

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2015-05-01

    The effect of inorganic carbon (IC) on nitrous oxide (N2O) production by ammonia oxidizing bacteria (AOB) was investigated over a concentration range of 0-12 mmol C/L, encompassing typical IC levels in a wastewater treatment reactors. The AOB culture was enriched along with nitrite-oxidizing bacteria (NOB) in a sequencing batch reactor (SBR) to perform complete nitrification. Batch experiments were conducted with continuous carbon dioxide (CO2) stripping or at controlled IC concentrations. The results revealed a linear relationship between N2O production rate (N2OR) and IC concentration (R(2) = 0.97) within the IC range studied, suggesting a substantial effect of IC on N2O production by AOB. Similar results were also obtained with an AOB culture treating anaerobic sludge digestion liquor. The fundamental mechanism responsible for this dependency is unclear; however, in agreement with previous studies, it was observed that the ammonia oxidation rate (AOR) was also influenced by the IC concentration, which could be well described by the Monod kinetics. These resulted in an exponential relationship between N2OR and AOR, as previously observed in experiments where AOR was altered by varying dissolved oxygen and ammonia concentrations. It is therefore possible that IC indirectly affected N2OR by causing a change in AOR. The observation in this study indicates that alkalinity (mostly contributed by IC) could be a significant factor influencing N2O production and should be taken into consideration in estimating and mitigating N2O emissions in wastewater treatment systems. PMID:25706224

  10. 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

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

    USGS Publications Warehouse

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

    2011-01-01

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

  12. Sampling frequency affects estimates of annual nitrous oxide fluxes

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  13. Sampling frequency affects estimates of annual nitrous oxide fluxes.

    PubMed

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

    2015-01-01

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

  14. 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

  15. 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. PMID:25121461

  16. 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

  17. [The advantage and harmful effects of nitrous oxide in dental management].

    PubMed

    Ogawa, Yojiro; Misaki, Toru

    2011-03-01

    Frequency of using nitrous oxide (N2O) in anesthetic field decreased recently by the influence of the environmental problems and the widespread use of intravenous agents. In dental treatment, however, inhalation sedation using low concentration of N2O has been effectively used to relax dental patients. Nitrous oxide inhalation sedation for dental treatment generally involves the use of a combination of low-dose N2O and high-dose oxygen. Low-dose N2O induces the relaxation of psychological tension in dental patients who have "dental phobia". Also, high-dose oxygen would contribute to manage "(pre) syncope" due to pain stimuli. Thus, N2O inhalation sedation is effective for the dental treatment, although the leak of N2O affects the health of dental staffs. The present review described the advantage and harmful effects of N2O in dental management. PMID:21485102

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  19. Nitrous Oxide Emissions in Medium and Coarse Textured Soils from Corn Production Under Conventional and Alternative Fertilizer Treatments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrogen (N) fertilizers applied in corn production cause soil-to-atmosphere direct emission of nitrous oxide (N2O), a major greenhouse gas. Some of the added N that leaches into groundwater as nitrate (NO3-) can subsequently be transformed to N2O, which represents an indirect source of N2O emission...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  1. 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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  4. 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

  5. Spectroscopic properties and electronic structure of pentammineruthenium(II) dinitrogen oxide and corresponding nitrosyl complexes: binding mode of N(2)O and reactivity.

    PubMed

    Paulat, Florian; Kuschel, Torben; Näther, Christian; Praneeth, V K K; Sander, Ole; Lehnert, Nicolai

    2004-11-01

    The spectroscopic properties and the electronic structure of the only nitrous oxide complex existing in isolated form, [Ru(NH(3))(5)(N(2)O)]X(2) (1, X = Br(-), BF(4)(-)), are investigated in detail in comparison to the nitric oxide precursor, [Ru(NH(3))(5)(NO)]X(3) (2). IR and Raman spectra of 1 and of the corresponding (15)NNO labeled complex are presented and assigned with the help of normal coordinate analysis (NCA) and density functional (DFT) calculations. This allows for the identification of the Ru-N(2)O stretch at approximately 300 cm(-)(1) and for the unambiguous definition of the binding mode of the N(2)O ligand as N-terminal. Obtained force constants are 17.3, 9.6, and 1.4 mdyn/A for N-N, N-O, and Ru-N(2)O, respectively. The Ru(II)-N(2)O bond is dominated by pi back-donation, which, however, is weak compared to the NO complex. This bond is further weakened by Coulomb repulsion between the fully occupied t(2g) shell of Ru(II) and the HOMO of N(2)O. Hence, nitrous oxide is an extremely weak ligand to Ru(II). Calculated free energies and formation constants for [Ru(NH(3))(5)(L)](2+) (L = NNO, N(2), OH(2)) are in good agreement with experiment. The observed intense absorption at 238 nm of 1 is assigned to the t(2g) --> pi(*) charge transfer transition. These data are compared in detail to the spectroscopic and electronic structural properties of NO complex 2. Finally, the transition metal centered reaction of nitrous oxide to N(2) and H(2)O is investigated. Nitrous oxide is activated by back-donation. Initial protonation leads to a weakening of the N-O bond and triggers electron transfer from the metal to the NN-OH ligand through the pi system. The implications of this mechanism for biological nitrous oxide reduction are discussed. PMID:15500336

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. Grazing and Nitrous Oxide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide emission rates are typically measured using ‘bottom up’ methods which involve placing airtight chambers over the soil surface and measuring the change in gas concentration over short time periods (e.g., 15-60 min.). Emission rates vary substantially both spatially and temporally and ma...

  11. 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. PMID:26983553

  12. US agricultural nitrous oxide emissions: context, status, and trends

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrogen (N) fertilizers have contributed to enormous increases in agricultural productivity in the US. However, nitrogen losses from agricultural systems have contributed to a number of deleterious environmental impacts, including a continuing increase in atmospheric nitrous oxide (N2O), a greenhou...

  13. 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

  14. [Nitrous oxide fluxes of constructed wetlands to treat sewage wastewater].

    PubMed

    Wu, Juan; Zhang, Jian; Jia, Wen-Lin; Xie, Hui-Jun; Roy, R Gu

    2009-11-01

    The nitrous oxide fluxes and ammonia-oxidizing bacterium in two typical constructed wetlands, i.e. subsurface flow (SF) and free water surface (FWS) were studied by the method of static chamber-gas chromatography. The results showed that the mean N2O fluxes were 296.5 microg x (m2 x h)(-1) and 28.2 microg x (m2 x h)(-1) respectively, and two typical wetlands were all the sources of atmosphere nitrous oxide as a whole. SF wetland exhibited a higher risk of N2O emissions, and the mean N2O flux in this system was higher than the values reported in the literature for ecosystems, e.g. farmland, forest, grassland and marsh. The nitrous oxide fluxes in test wetlands presented obvious seasonal and diurnal variation, and the highest N2O emission flux was in July. The highest flux was (762.9 +/- 239.3) microg x (m2 x h)(-1) and (91.9 +/- 20.3) microg x (m2 x h)(-1) in SF and FWS wetlands, respectively. The peak flux mostly occurred around midday, whereas the minimum flux likely occurred in the early morning. The results indicated that the growth of Phragmites australis and temperature were the key factors controlling the variation of N2O fluxes. The average N2O emission from the microsites above the inflow zones was higher than that above the outflow microsites. High influent strength promoted nitrification and denitrification, and high fluxes were obtained. The clone results showed that Nitrosomonas and Nitrosospira were the main ammonia-oxidizing microorganisms contributing to N2O production in constructed wetlands. PMID:20063721

  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. Fertilizer management effects on nitrate leaching and indirect nitrous oxide emissions in irrigated potato production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Potato is a nitrogen (N) intensive crop with high potential for nitrate (NO3-) losses, particularly when irrigated. The high leaching potential also represents a potential source of indirect nitrous oxide (N2O) emissions resulting from the transformation of NO3- to N2O after it leaves the fertilized...

  17. 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...

  18. 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...

  19. 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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  1. Nitrous Oxide Gas Fluxes in a Potato Field Following Application of Urea and Coated Urea Fertilizers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Application of urea and other forms of nitrogen (N) fertilizer can generate atmospheric emissions of nitrous oxide (N2O), which is a potent greenhouse gas. Field experiments were conducted on a loamy sand soil in Becker, Minnesota to evaluate the effects of soluble and coated forms of urea on N2O fl...

  2. 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...

  3. 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...

  4. 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 ...

  5. 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 ...

  6. 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...

  7. Fertilizer induced losses of nitrous oxide gas from Montana dryland cropping systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrogen fertilization to crops contributes a significant portion of soil nitrous oxide (N2O) emission, a greenhouse gas responsible for global warming. This information is, however, lacking in the dryland cropping system in the northern Great Plains. Soil N2O and methane (CH4) fluxes from May to No...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  9. 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...

  10. Nitrous Oxide Emissions from a Bermudagrass Pasture: Interseeded Winter Rye and Poultry Litter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The impact of poultry litter applications and interseeded winter rye on nitrous oxide (N2O) emissions from pasture is not well documented. This study was conducted to estimate soil surface N2O fluxes as affect by poultry litter applications and interseeded winter rye as well as weather and soil vari...

  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. Comparison of DAYCENT-Simulated and Measured Nitrous Oxide Emission from a Corn Field

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurate assessment of nitrous oxide (N2O) emission from soil requires continuous year-round and spatially extensive monitoring. Alternatively, simulation models can predict N2O fluxes based on climatic, soil and agricultural system input data. DAYCENT is an ecosystem model that simulates, among oth...

  13. 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 ...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  15. Isotopic Fractionation of Atmospheric Nitrous Oxide

    NASA Astrophysics Data System (ADS)

    Morgan, C. G.; Yung, Y. L.; Allen, M. A.; Blake, G. A.; Liang, N. C.

    2002-05-01

    Nitrous oxide (N2O) is an important greenhouse gas in the Earth's atmosphere, with both natural and anthropogenic sources. Much effort has been made in using isotopic signatures as a way to constrain the magnitudes of the various sources of N2O. A necessary part of this task is to understand what effect the atmosphere, which is the major sink of N2O, has on these isotopic signatures. Using a two-dimensional (2-D) chemical transport model, we investigated the isotopic fractionation of N2O in the Earth's atmosphere, and we compared the results of our model with laboratory experiments and atmospheric observations. Isotopic fractionation of N2O can occur through photolytic destruction and through a reaction with singlet oxygen. We used three different methods of calculating photolytic cross-sections for each of the major isotopomers of N2O. We found that although the Yung and Miller approach (Science, 278, 1778 (1997)), which postulates that changes in the zero point energies between the isotopomers causes shifts in their respective absorption profiles, can model the pattern of enrichment factors for each isotopomer relative to each other, this approach underestimates the magnitude of the enrichment factors. The ab initio approach by Johnson et al. (JPCA, 105, 8672 (2001)) provided a better fit to the magnitudes of the enrichment factors, with the notable exception of the 15N14N16O isotopomer. A simpler, semi-empirical approach by Blake et al. (2002, in preparation) was able to model the magnitude of all the enrichment factors, including the one for the 15N14N16O isotopomer. We also explored the contributions and effects that the singlet oxygen reaction, climatology and transport have on atmospheric isotopic fractionation.

  16. Global agriculture and nitrous oxide emissions

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  17. Analysis of microbial populations, denitrification, and nitrous oxide production in riparian buffers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Riparian buffers are used extensively to protect water bodies from nonpoint source nitrogen pollution. However there is relatively little information on the impact of these buffers on production of nitrous oxide (N2O). In this study, we assessed nitrous oxide production in riparian buffers of the so...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  19. Infrared Spectroscopy of (N_2O)_n^- and (N_2O)mO^- Cluster Anions

    NASA Astrophysics Data System (ADS)

    Thompson, Michael C.; Weber, J. Mathias

    2015-06-01

    We report infrared photodissociation spectra of nitrous oxide cluster anions, (N_2O)_n^- (n=7-11) and (N_2O)mO^- (m=1-13). Structural changes of the charge carrier in the clusters are driven by increasing levels of solvation. The spectra are interpreted by comparison with quantum chemical calculations.

  20. 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. PMID:24001217

  1. 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.

  2. Catalytic decomposition of nitrous oxide monopropellant for hybrid motor ignition

    NASA Astrophysics Data System (ADS)

    Wilson, Matthew

    Nitrous oxide (N2O) is an inexpensive and readily available non-toxic rocket motor oxidizer. It is the most commonly used oxidizer for hybrid bipropellant rocket systems, and several bipropellant liquid rocket designs have also used nitrous oxide. In liquid form, N2O is highly stable, but in vapor form it has the potential to decompose exothermically, releasing up to 1865 Joules per gram of vapor as it dissociates into nitrogen and oxygen. Consequently, it has long been considered as a potential "green" replacement for existing highly toxic and dangerous monopropellants. This project investigates the feasibility of using the nitrous oxide decomposition reaction as a monopropellant energy source for igniting liquid bipropellant and hybrid rockets that already use nitrous oxide as the primary oxidizer. Because nitrous oxide is such a stable propellant, the energy barrier to dissociation is quite high; normal thermal decomposition of the vapor phase does not occur until temperatures are above 800 C. The use of a ruthenium catalyst decreases the activation energy for this reaction to allow rapid decomposition below 400 C. This research investigates the design for a prototype device that channels the energy of dissociation to ignite a laboratory scale hybrid rocket motor.

  3. Nitrous oxide dynamics in low oxygen regions of the Pacific: insights from the MEMENTO database

    NASA Astrophysics Data System (ADS)

    Zamora, L. M.; Oschlies, A.; Bange, H. W.; Huebert, K. B.; Craig, J. D.; Kock, A.; Löscher, C. R.

    2012-12-01

    The eastern tropical Pacific (ETP) is believed to be one of the largest marine sources of the greenhouse gas nitrous oxide (N2O). Future N2O emissions from the ETP are highly uncertain because oxygen minimum zones are expected to expand, affecting both regional production and consumption of N2O. Here we assess three primary uncertainties in how N2O may respond to changing O2 levels: (1) the relationship between N2O production and O2 (is it linear or exponential at low O2 concentrations?), (2) the cutoff point at which net N2O production switches to net N2O consumption (uncertainties in this parameterisation can lead to differences in model ETP N2O concentrations of more than 20%), and (3) the rate of net N2O consumption at low O2. Based on the MEMENTO database, which is the largest N2O dataset currently available, we find that N2O production in the ETP increases linearly rather than exponentially with decreasing O2. Additionally, net N2O consumption switches to net N2O production at ~ 10 μM O2, a value in line with recent studies that suggest consumption occurs on a larger scale than previously thought. N2O consumption is on the order of 0.01-1 mmol N2O m-3 yr-1 in the Peru-Chile Undercurrent. Based on these findings, it appears that recent studies substantially overestimated N2O production in the ETP. In light of expected deoxygenation and the higher than previously expected point at which net N2O production switches to consumption, there is enough uncertainty in future N2O production that even the sign of future changes is still unclear.

  4. 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.

  5. Denitirification and N2O emission in arable soils: Effect of tillage, N source and soil moisture.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is a lack of understanding of how tillage, N source and moisture status control soil respiration, nitrous oxide and denitrification. A laboratory investigation was performed to quantify the interaction of carbon dioxide (CO2), nitrous oxide (N2O) and dinitrogen (N2)+N2O (representing denitrifi...

  6. Fertilizer Source Impacts on Nitrous and Nitric Oxide Emissions in Corn Cropping Systems of the Upper Midwest U.S.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It is well-established that the application of nitrogen fertilizer to soil results in emissions of nitric oxide (NO) and nitrous oxide (N2O), which are gases that have important local, regional, and global air quality impacts. Despite hundreds of studies reporting measurements of NO and N2O emission...

  7. A UK inventory of nitrous oxide emissions from farmed livestock

    NASA Astrophysics Data System (ADS)

    Chadwick, D. R.; Sneath, R. W.; Phillips, V. R.; Pain, B. F.

    A UK inventory of the nitrous oxide (N 2O) emissions from farmed livestock was compiled to identify areas where potential abatement practices may be effective. Where possible, emission factors based on direct experimental data gathered under UK conditions were used, but published data were used when this was not feasible, together with statistical information, which included details of numbers of animals within each category of a species, animal liveweights, number of days housed, excretal rates and volumes of manures in stores. Total N 2O emissions were calculated for each component of livestock production systems, i.e. animal houses, manure stores, following application of manures to land and during grazing. Emissions were also estimated from land used for forage conservation and tillage. Total annual N 2O emissions from UK farmed livestock, based mainly on 1996 animal census data, were estimated to be 38.27 kt. The two main terms were 22.66 kt N 2O from mineral fertilisers after application to soils and 5.61 kt N 2O from stored manures (mainly in the form of farmyard manure). Within buildings, poultry were the largest contributors of N 2O, 2.97 kt, followed by cattle, 1.62 kt. Within the total emissions from stored manures, cattle were the largest contributors of N 2O, 3.58 kt, followed by poultry, 1.86 kt. Dietary manipulation and a move from solid manure based systems to slurry based systems appear to be promising abatement practices.

  8. 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

  9. Nitrous oxide emissions from light duty vehicles

    NASA Astrophysics Data System (ADS)

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

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

  10. N2O emission in short-cut simultaneous nitrification and denitrification process: dynamic emission characteristics and succession of ammonia-oxidizing bacteria.

    PubMed

    Yan, Yingyan; Li, Ping; Wu, Jinhua; Zhu, Nengwu; Wu, Pingxiao; Wang, Xiangde

    2014-01-01

    A sequencing batch airlift reactor was used to investigate the characteristics of nitrous oxide (N2O) emission and the succession of an ammonia-oxidizing bacteria (AOB) community. The bioreactor could successfully switch from the complete simultaneous nitrification and denitrification (SND) process to the short-cut SND process by increasing the influent pH from 7.0-7.3 to 8.0-8.3. The results obtained showed that, compared with the complete SND process, the TN removal rate and SND efficiency were improved in the short-cut SND process by approximately 13 and 11%, respectively, while the amount of N2O emission was nearly three times larger than that in the complete SND process. The N2O emission was closely associated to nitrite accumulation. Analysis of the AOB microbial community showed that nitrifier denitrification by Nitrosomonas-like AOB could be an important pathway for the enhancement of N2O emission in the short-cut SND process. PMID:24960019

  11. 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

  12. 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

  13. 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

  14. 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.

  15. 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

  16. Genetic and environmental controls on nitrous oxide accumulation in lakes.

    PubMed

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

    2015-01-01

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

  17. 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

  18. 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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  20. Fertilizer source and tillage effects on yield-scaled nitrous oxide emissions in a corn cropping system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn production consumes approximately 50% of all nitrogen (N) fertilizers applied to agricultural crops in the U.S. and therefore represents a large potential source of emissions of the potent greenhouse gas nitrous oxide (N2O) relative to other crops. Quantification of N2O emissions resulting from...

  1. 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...

  2. 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 ...

  3. Testing DAYCENT Model Simulations of Corn Yields and Nitrous Oxide Emissions in Irrigated Tillage Systems in Colorado

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural soils are responsible for the majority of nitrous oxide (N2O) emissions in the USA. Irrigated cropping, particularly in the western USA, is an important source of N2O emissions. However, the impacts of tillage intensity and N fertilizer amount and type have not been extensively studied ...

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  5. Active N(2)O emission from bacterial microbiota of Andisol farmland and characterization of some N(2)O emitters.

    PubMed

    Takeda, Hisahaya; Takahashi, Naoki; Hatano, Ryusuke; Hashidoko, Yasuyuki

    2012-08-01

    Andisol in farmland located in Hokkaido, Japan, is known to actively flux nitrous oxide (N(2)O) during the spring to summer seasons. Using a culturing system which mimics farm soils, nitrous oxide (N(2)O) emission potentials of the soils or soil microorganisms were investigated. A total of thirty-three soil samples from the farmland showed high N(2)O production potential, of which the maximum level of N(2)O emission was 3.69 μg per ml of the cultured medium per day (ml(-1) d(-1)) in the assay system. However, only three eubacteria (Leptothrix sp., Paenibacillus sp., and Streptomyces sp.) were isolated as culturable N(2)O emitters among a total of 92 bacterial isolates and 2 fungi obtained from the assayed soil suspensions. N(2)O production from all the isolated N(2)O emitters was more active within a weakly acidic region (pH 4.5-5.0) than neutral regions. However, unlike N(2)O emitters isolated from tropical peat soils, they did not respond to supplemental 0.5% sucrose. In the acetylene inhibition assay for the evaluation of complete denitrification, Leptothrix sp. P3-15D and Streptomyces sp. M2-0C indicated that these culturable N(2)O emitters are not effective denitrifiers but weak N(2)O emitters in the Andisol. Conversely, Rhodococcus sp. that was isolated from the Andisol collected in another season using a KNO(3)-enriched plate, showed 3.2-fold higher N(2)O emission with 10% C(2) H(2). Instead of the culturable bacteria, it is probable that the N(2)O emitters in viable but non-culturable (VBNC) state or obligately anaerobic denitrifiers are the major contributors to N(2)O emission from the vitric Andisol. PMID:22144290

  6. Nitrogen source effects on nitrous oxide emissions from irrigated cropping systems in Colorado. American Chemical Society Symposium Series

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrogen (N) fertilization is essential in most irrigated cropping systems to optimize crop yields and economic returns. Application of inorganic N fertilizers to these cropping systems generally results in increased nitrous oxide (N2O-N) emissions. Nitrous oxide emissions resulting from the appli...

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  8. 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).

  9. 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

  10. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  12. Nitrous oxide supersaturation at the liquid/air interface of animal waste.

    PubMed

    Makris, Konstantinos C; Andra, Syam S; Hardy, Michael; Sarkar, Dibyendu; Datta, Rupali; Bach, Stephan B H; Mullens, Conor P

    2009-12-01

    Concentrated animal feeding operations around the globe generate large amounts of nitrous oxide (N(2)O) in the surrounding atmosphere. Liquid animal waste systems have received little attention with respect to N(2)O emissions. We hypothesized that the solution chemistry of animal waste aqueous suspensions would promote conditions that lead to N(2)O supersaturation at the liquid/air interface. The concentration of dissolved N(2)O in poultry litter (PL) aqueous suspensions at 25 degrees C was 0.36 microg N(2)O mL(-1), at least an order of magnitude greater than that measured in water in equilibrium with ambient air, suggesting N(2)O supersaturation. There was a nonlinear increase in the N(2)O Henry constants of PL from 2810 atm/mole fraction at 35 degrees C to 17 300 atm/mole fraction at 41 degrees C. The extremely high N(2)O Henry constants were partially ascribed to N(2)O complexation with aromatic moieties. Complexed N(2)O structures were unstable at temperatures > 35 degrees C, supplying the headspace with additional free N(2)O concentrations. PMID:19573962

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

    PubMed

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

    2003-08-15

    Diffuse pollution of groundwater by agriculture has caused elevated concentrations of nitrate (NO3-) and nitrous oxide (N2O) in regional aquifers. N2O is an important "greenhouse" gas, yet there are few estimates of indirect emissions of N2O from regional aquifers. In this study, high concentrations of N2O (mean 602 nM) were measured in the unconfined Chalk aquifer of eastern England, in an area of intensive agriculture. In contrast, pristine groundwaters from upland regions of England and Scotland, with predominantly natural vegetation cover, were found to have much lower concentrations of N2O (mean 27 nM). A positive relationship between N2O and NO3- concentrations and delta18O-NO3 values of between 3.36 and 16.00/1000 suggest that nitrification is the principal source of N2O. A calculated emission factor (EF5-g) of 0.0019 for indirect losses of N2O from Chalk groundwater is an order of magnitude lower than the value of 0.015 currently used in the Intergovernmental Panel on Climate Change (IPCC) methodology for assessing agricultural emissions. A flux of N2O from the major UK aquifers of 0.04 kg N2O-N ha(-1) a(-1) has been calculated using two approaches and suggests that indirect losses of N2O from regional aquifers are much less significant (<1%) than direct emissions from agricultural soils. PMID:12953859

  14. 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.

  15. Kinetics of nitrous oxide production by denitrification in municipal solid waste.

    PubMed

    Wu, Chuanfu; Shimaoka, Takayuki; Nakayama, Hirofumi; Komiya, Teppei

    2015-04-01

    As one of the Nitrous Oxide (N2O) production pathways, denitrification plays an important role in regulating the emission of N2O into the atmosphere. In this study, the influences of different substrate concentrations and transient conditions on the denitrification rate and N2O-reducing activities were investigated. Results revealed that N2O production rates (i.e. denitrification rates) were stimulated by increased total organic carbon (TOC) concentration, while it was restrained under high oxygen concentrations. Moreover, the impact of nitrate concentrations on N2O production rates depended on the TOC/NO3--N ratios. All the N2O production rate data fitted well to a multiplicative Monod equation, with terms describing the influence of TOC and nitrate concentrations, and an Arrhenius-type equation. Furthermore, results demonstrated that high temperatures minimized the N2O-reducing activities in aged municipal solid waste, resulting in an accumulation of N2O. On the other hand, a transient condition caused by changing O2 concentrations may strongly influence the N2O production rates and N2O-reducing activities in solid waste. Finally, based on the results, we believe that a landfill aeration strategy properly designed to prevent rising temperatures and to cycle air injection is the key to reducing emissions of N2O during remediation of old landfills by means of in situ aeration. PMID:25697806

  16. Nitrous oxide generation in denitrifying phosphorus removal process: main causes and control measures.

    PubMed

    Li, Cong; Zhang, Jian; Liang, Shuang; Ngo, Huu Hao; Guo, Wenshan; Zhang, Yingying; Zou, Yina

    2013-08-01

    Despite the many benefits of denitrifying phosphorus removal process, the significant generation of nitrous oxide (N2O), a potent greenhouse gas, remains a problem for this innovative and promising process. To better understand and more effectively control N2O generation in denitrifying phosphorus removal process, batch experiments were carried out to investigate the main causes of N2O generation, based on which the control measures were subsequently proposed. The results showed that N2O generation accounted for 0.41 % of the total nitrogen removal in denitrifying phosphorus removal process, whereas, in contrast, almost no N2O was generated in conventional denitrification process. It was further demonstrated that the weak competition of N2O reductase for electrons and the high nitrite accumulation were the two main causes for N2O generation, evidenced by N2O production and reduction rates under different conditions. Accordingly, the reduction of N2O generation was successfully achieved via two control measures: (1) the use of continuous nitrate addition reducing N2O generation by around 91.4 % and (2) the use of propionate as the carbon source reducing N2O generation by around 69.8 %. PMID:23407928

  17. Aerobic nitrous oxide production through N-nitrosating hybrid formation in ammonia-oxidizing archaea.

    PubMed

    Stieglmeier, Michaela; Mooshammer, Maria; Kitzler, Barbara; Wanek, Wolfgang; Zechmeister-Boltenstern, Sophie; Richter, Andreas; Schleper, Christa

    2014-05-01

    Soil emissions are largely responsible for the increase of the potent greenhouse gas nitrous oxide (N2O) in the atmosphere and are generally attributed to the activity of nitrifying and denitrifying bacteria. However, the contribution of the recently discovered ammonia-oxidizing archaea (AOA) to N2O production from soil is unclear as is the mechanism by which they produce it. Here we investigate the potential of Nitrososphaera viennensis, the first pure culture of AOA from soil, to produce N2O and compare its activity with that of a marine AOA and an ammonia-oxidizing bacterium (AOB) from soil. N. viennensis produced N2O at a maximum yield of 0.09% N2O per molecule of nitrite under oxic growth conditions. N2O production rates of 4.6±0.6 amol N2O cell(-1) h(-1) and nitrification rates of 2.6±0.5 fmol NO2(-) cell(-1) h(-1) were in the same range as those of the AOB Nitrosospira multiformis and the marine AOA Nitrosopumilus maritimus grown under comparable conditions. In contrast to AOB, however, N2O production of the two archaeal strains did not increase when the oxygen concentration was reduced, suggesting that they are not capable of denitrification. In (15)N-labeling experiments we provide evidence that both ammonium and nitrite contribute equally via hybrid N2O formation to the N2O produced by N. viennensis under all conditions tested. Our results suggest that archaea may contribute to N2O production in terrestrial ecosystems, however, they are not capable of nitrifier-denitrification and thus do not produce increasing amounts of the greenhouse gas when oxygen becomes limiting. PMID:24401864

  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. 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

  1. 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.

  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. 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.

  4. 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

  5. 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.

  6. Nitrous oxide uptake rates in boreal coniferous forests are associated with soil characteristics

    NASA Astrophysics Data System (ADS)

    Siljanen, Henri; Biasi, Christina; Martikainen, Pertti

    2014-05-01

    Nitrous oxide (N2O) is a strong greenhouse gas and a significant contributor to the destruction of the ozone layer. The radiative forcing of N2O is considered to be 320 more efficient than carbon dioxide.The major portion of global N2O is emitted from agricultural soils. There are studies suggesting that N2O has also a sink in forest soils. However there is relatively limited knowledge on factors controlling N2O consumption in forest soils. Hence N2O consumption was studied in boreal coniferous forests having different forest cover, soil chemical and physical structure and land-use history. The N2O consumption was measured by static chamber technique in the field across spatio-seasonal sampling design. Typical and atypical denitrifiers were quantified with nosZ functional gene marker. Additionally chemical and physical environmental parameters were analyzed to link N2O flux, microbial community and composition of soils. Nitrous oxide uptake could be associated with specific ecosystem and environmental conditions. Soil physical structure and land-use history were shown to be prior factors determining the strength of the uptake rate.

  7. 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

  8. Flume experiments elucidate relationships between stream morphology, hyporheic residence time, and nitrous oxide production

    NASA Astrophysics Data System (ADS)

    Quick, Annika; Farrell, Tiffany B.; Reeder, William Jeffrey; Feris, Kevin P.; Tonina, Daniele; Benner, Shawn G.

    2015-04-01

    The hyporheic zone is a potentially important producer of nitrous oxide, a powerful greenhouse gas. The location and magnitude of nitrous oxide generation within the hyporheic zone involves complex interactions between multiple nitrogen species, redox conditions, microbial communities, and hydraulics. To better understand nitrous oxide generation and emissions from streams, we conducted large-scale flume experiments in which we monitored pore waters along hyporheic flow paths within stream dune structures. Measurements of dissolved oxygen, ammonia, nitrate, nitrite, and dissolved nitrous oxide showed distinct spatial relationships reflecting redox changes along flow paths. Using residence times along a flow path, clear trends in oxygen conditions and nitrogen species were observed. Three dune sizes were modeled, resulting in a range of residence times, carbon reactivity levels and respiration rates. We found that the magnitude and location of nitrous oxide production in the hyporheic zone is related to nitrate loading, dune morphology, and residence time. Specifically, increasing exogenous nitrate levels in surface water to approximately 3 mg/L resulted in an increase in dissolved N2O concentrations greater than 500% (up to 10 µg/L N-N2O) in distinct zones of specific residence times. We also found, however, that dissolved N2O concentrations decreased to background levels further along the flow path due to either reduction of nitrous oxide to dinitrogen gas or degassing. The decrease in measurable N2O along a flow path strongly suggests an important relationship between dune morphology, residence time, and nitrous oxide emissions from within stream sediments. Relating streambed morphology and loading of nitrogen species allows for prediction of nitrous oxide production in the hyporheic zone of natural systems.

  9. 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

  10. 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

  11. Meta-Analysis of Environmental Impacts on Nitrous Oxide Release in Response to N Amendment

    PubMed Central

    Aronson, Emma L.; Allison, Steven D.

    2012-01-01

    Atmospheric nitrous oxide (N2O) accounts for approximately 5% of the global greenhouse effect and destroys stratospheric ozone. Soils are the most important source of N2O, which is produced during nitrification and denitrification. To assess the impact of environmental variables and ecosystems on N2O flux, we performed a meta-analysis comparing N2O flux in N amended and matched control plots in non-agricultural soils. We found that N2O release increased with N amendment in the short term. Although there were few studies in shrubland, this ecosystem showed the greatest response. The N2O response to N amendment was greater in year-round studies and in studies with more measurements, but lower in longer studies. The N2O response was greater at higher latitudes and precipitation rates. We also observed an unexpected 55% decline in the N2O response to N amendment over the 23 years covered by the studies. This pattern may reflect a suppression of the N2O response from long-term N deposition accumulation, particularly in temperate regions. Although short term increases in reactive N entering natural systems may cause positive feedbacks to the release of N2O, this effect may diminish over time in locations with high rates of N deposition. PMID:22866053

  12. 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

  13. 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

    2015-01-01

    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

  14. 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.

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

    PubMed

    Ni, Bing-Jie; Yuan, Zhiguo

    2015-12-15

    Nitrous oxide (N2O) can be emitted from wastewater treatment contributing to its greenhouse gas footprint significantly. Mathematical modeling of N2O emissions is of great importance toward the understanding and reduction of the environmental impact of wastewater treatment systems. This article reviews the current status of the modeling of N2O emissions from wastewater treatment. The existing mathematical models describing all the known microbial pathways for N2O production are reviewed and discussed. These included N2O production by ammonia-oxidizing bacteria (AOB) through the hydroxylamine oxidation pathway and the AOB denitrification pathway, N2O production by heterotrophic denitrifiers through the denitrification pathway, and the integration of these pathways in single N2O models. The calibration and validation of these models using lab-scale and full-scale experimental data is also reviewed. We conclude that the mathematical modeling of N2O production, while is still being enhanced supported by new knowledge development, has reached a maturity that facilitates the estimation of site-specific N2O emissions and the development of mitigation strategies for a wastewater treatment plant taking into the specific design and operational conditions of the plant. PMID:26451976

  17. Treatment of N2O in pulsed microwave torch discharge

    NASA Astrophysics Data System (ADS)

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

    2004-03-01

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

  18. 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

  19. 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

  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. Multireference perturbation theory (MRPT2) study on N 2O capture and activation by excited states of Rh atom and cation

    NASA Astrophysics Data System (ADS)

    Poulain, Enrique; Olvera-Neria, Oscar; Bertin, Virineya

    2010-07-01

    Nitrous oxide (N 2O) is an intermediate compound in three-ways exhaust-pipes catalysis. Rh and Rh + + N 2O reactions are calculated at ab initio MRPT2 level, in Cs symmetry and for many multiplicities to find N 2O capture and activation. Rh ground state does not capture N 2O; however some excited states spontaneously capture and activate it, where only RhN 2O (b 6A') and (e 8A″) activate N 2O: RhN 2O → RhO + N 2 and RhN 2O → RhN 2 + O, respectively but never break N-N bond. Rh + ground state weakly capture N 2O, but only one Rh + excited state captures and activates N 2O. N 2O activation by Rh atom and cation do not involve any transition states.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

    Beaulieu, Jake J.; Nietch, Christopher T.; Young, Jade L.

    2015-10-01

    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 reservoirs. Due to long water residence times and high nitrogen (N) loading rates, reservoirs support substantial N processing and therefore may be particularly important sites of N2O production. Predicting N2O emissions from reservoirs is difficult due to complex interactions between microbial N processing in the oxygen-poor hypolimnion and oxygen-rich epilimnion. Here we present the results of a survey of N2O depth profiles in 20 reservoirs draining a broad range of land use conditions in four states in the U.S. Nitrous oxide was supersaturated in the epilimnion of 80% of the reservoirs and was undersaturated in only one, indicating that reservoirs in this region are generally a source of N2O to the atmosphere. Nitrous oxide was undersaturated in the hypolimnion of 10 reservoirs, supersaturated in 9, and transitioned from supersaturation to undersaturation in 1 reservoir that was monitored periodically from midsummer to fall. All reservoirs with a mean hypolimnion nitrate concentration less than 50 µg N L-1 showed evidence of net N2O consumption in the hypolimnion. All reservoirs sampled during lake turnover supported N2O production throughout the water column. These results indicate that N2O dynamics in reservoirs differ widely both among systems and through time but can be predicted based on N and oxygen availability and degree of thermal stratification.

  4. 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

  5. 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

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

    PubMed

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

    2014-01-01

    Denitrifying activities and nitrous oxide (N2O) emission during denitrification can be affected by copper concentrations. Different denitrifiers were acclimated in sequencing batch reactors with acetate or methanol as the electron donor and nitrate as the electron acceptor. The effect of copper concentrations on the denitrifying activity and N2O emission for the acclimated denitrifiers was examined in batch experiments. Denitrifying activities of the acclimated denitrifiers declined with increasing copper concentrations, and the copper concentration exhibited a higher effect on denitrifiers acclimated with acetate than those acclimated with methanol. Compared with the control without the addition of copper, at the copper concentration of 1 mg/L, the acetate utilization rate reduced by 89% for acetate-acclimated denitrifiers, while the methanol utilization rate only reduced by 15% for methanol-acclimated denitrifiers. Copper also had different effects on N2O emission during denitrification carried out by various types of denitrifiers. For the acetate-acclimated denitrifiers, N2O emission initially increased and then decreased with increasing copper concentrations, while for the methanol-acclimated denitrifiers, N2O emission decreased with increasing copper concentrations. PMID:24569272

  7. 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.

  8. Infrared spectroscopic studies on the cluster size dependence of charge carrier structure in nitrous oxide cluster anions.

    PubMed

    Thompson, Michael C; Weber, J Mathias

    2016-03-14

    We report infrared photodissociation spectra of nitrous oxide cluster anions of the form (N2O)nO(-) (n = 1-12) and (N2O)n (-) (n = 7-15) in the region 800-1600 cm(-1). The charge carriers in these ions are NNO2 (-) and O(-) for (N2O)nO(-) clusters with a solvation induced core ion switch, and N2O(-) for (N2O)n (-) clusters. The N-N and N-O stretching vibrations of N2O(-) (solvated by N2O) are reported for the first time, and they are found at (1595 ± 3) cm(-1) and (894 ± 5) cm(-1), respectively. We interpret our infrared spectra by comparison with the existing photoelectron spectroscopy data and with computational data in the framework of density functional theory. PMID:26979688

  9. Infrared spectroscopic studies on the cluster size dependence of charge carrier structure in nitrous oxide cluster anions

    NASA Astrophysics Data System (ADS)

    Thompson, Michael C.; Weber, J. Mathias

    2016-03-01

    We report infrared photodissociation spectra of nitrous oxide cluster anions of the form (N2O)nO- (n = 1-12) and (N2O)n- (n = 7-15) in the region 800-1600 cm-1. The charge carriers in these ions are NNO2- and O- for (N2O)nO- clusters with a solvation induced core ion switch, and N2O- for (N2O)n- clusters. The N-N and N-O stretching vibrations of N2O- (solvated by N2O) are reported for the first time, and they are found at (1595 ± 3) cm-1 and (894 ± 5) cm-1, respectively. We interpret our infrared spectra by comparison with the existing photoelectron spectroscopy data and with computational data in the framework of density functional theory.

  10. 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...

  11. 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 ...

  12. Mathematical Modeling of Nitrous Oxide Production during Denitrifying Phosphorus Removal Process.

    PubMed

    Liu, Yiwen; Peng, Lai; Chen, Xueming; Ni, Bing-Jie

    2015-07-21

    A denitrifying phosphorus removal process undergoes frequent alternating anaerobic/anoxic conditions to achieve phosphate release and uptake, during which microbial internal storage polymers (e.g., Polyhydroxyalkanoate (PHA)) could be produced and consumed dynamically. The PHA turnovers play important roles in nitrous oxide (N2O) accumulation during the denitrifying phosphorus removal process. In this work, a mathematical model is developed to describe N2O dynamics and the key role of PHA consumption on N2O accumulation during the denitrifying phosphorus removal process for the first time. In this model, the four-step anoxic storage of polyphosphate and four-step anoxic growth on PHA using nitrate, nitrite, nitric oxide (NO), and N2O consecutively by denitrifying polyphosphate accumulating organisms (DPAOs) are taken into account for describing all potential N2O accumulation steps in the denitrifying phosphorus removal process. The developed model is successfully applied to reproduce experimental data on N2O production obtained from four independent denitrifying phosphorus removal study reports with different experimental conditions. The model satisfactorily describes the N2O accumulation, nitrogen reduction, phosphate release and uptake, and PHA dynamics for all systems, suggesting the validity and applicability of the model. The results indicated a substantial role of PHA consumption in N2O accumulation due to the relatively low N2O reduction rate by using PHA during denitrifying phosphorus removal. PMID:26114730

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

    SciTech Connect

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

    1996-07-01

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

  14. Clinical experience with TENS and TENS combined with nitrous oxide-oxygen. Report of 371 patients.

    PubMed Central

    Quarnstrom, F. C.; Milgrom, P.

    1989-01-01

    Transcutaneous electrical nerve stimulation (TENS) alone or TENS combined with nitrous oxide-oxygen (N2O) was administered for restorative dentistry without local anesthesia to 371 adult patients. A total of 55% of TENS alone and 84% of TENS/N2O visits were rated successful. A total of 53% of TENS alone and 82% of TENS/N2O patients reported slight or no pain. In multivariable analyses, pain reports were related to the anesthesia technique and patient fear and unrelated to sex, race, age, tooth, or depth of preparation. PMID:2604059

  15. 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

  16. Transatlantic equatorial distribution of nitrous oxide and methane

    NASA Astrophysics Data System (ADS)

    Oudot, Claude; Jean-Baptiste, Philippe; Fourré, Elise; Mormiche, Claire; Guevel, Michael; Ternon, Jean-François; Le Corre, Pierre

    2002-07-01

    During January-March 1993, the vertical distributions of dissolved nitrous oxide (N 2O) and methane (CH 4), and their atmospheric mixing ratios were measured in the equatorial Atlantic on the WOCE lines A6 (7°30'N) and A7 (4°30'S). Measured mean N 2O and CH 4 atmospheric mixing ratios were 0.316 and 1.786 ppm respectively, with an analytical precision of 1%. Surface waters were everywhere supersaturated with both gases (mean excess ΔN 2O=8% and ΔCH 4=32%), with significantly higher values close to the continents. The N 2O vertical distributions on both sections display a broad maximum centred near 400 m depth, at the level of the oxygen minimum. The CH 4 vertical distributions also show a sharp subsurface maximum at the base of the mixed layer, associated with a chlorophyll a maximum. Computed N 2O and CH 4 sea-air fluxes are in the range 1.1-1.8 μmol m -2 d -1 and 1.2-2.0 μmol m -2 d -1 respectively. For N 2O, we calculate that the upward transport through the thermocline matches the horizontal transport in the mixed layer and the emission to the atmosphere. Hence, the N 2O budget is balanced within the experimental uncertainties. This is not the case for CH 4, whose vertical transport from the maximum concentration layer accounts for <10% of the sea-air flux. It follows that the CH 4 budget requires a sustained production within the mixed layer itself to maintain CH 4 supersaturation and balance its escape to the atmosphere.

  17. 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

  18. 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

  19. 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.

  20. 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.

  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. 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.

  3. 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.

  4. 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. PMID:23880433

  5. Isotopic evidence for nitrous oxide production pathways in a partial nitritation-anammox reactor.

    PubMed

    Harris, Eliza; Joss, Adriano; Emmenegger, Lukas; Kipf, Marco; Wolf, Benjamin; Mohn, Joachim; Wunderlin, Pascal

    2015-10-15

    Nitrous oxide (N2O) production pathways in a single stage, continuously fed partial nitritation-anammox reactor were investigated using online isotopic analysis of offgas N2O with quantum cascade laser absorption spectroscopy (QCLAS). N2O emissions increased when reactor operating conditions were not optimal, for example, high dissolved oxygen concentration. SP measurements indicated that the increase in N2O was due to enhanced nitrifier denitrification, generally related to nitrite build-up in the reactor. The results of this study confirm that process control via online N2O monitoring is an ideal method to detect imbalances in reactor operation and regulate aeration, to ensure optimal reactor conditions and minimise N2O emissions. Under normal operating conditions, the N2O isotopic site preference (SP) was much higher than expected - up to 40‰ - which could not be explained within the current understanding of N2O production pathways. Various targeted experiments were conducted to investigate the characteristics of N2O formation in the reactor. The high SP measurements during both normal operating and experimental conditions could potentially be explained by a number of hypotheses: i) unexpectedly strong heterotrophic N2O reduction, ii) unknown inorganic or anammox-associated N2O production pathway, iii) previous underestimation of SP fractionation during N2O production from NH2OH, or strong variations in SP from this pathway depending on reactor conditions. The second hypothesis - an unknown or incompletely characterised production pathway - was most consistent with results, however the other possibilities cannot be discounted. Further experiments are needed to distinguish between these hypotheses and fully resolve N2O production pathways in PN-anammox systems. PMID:26164660

  6. 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.

  7. 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

  8. Seasonal variations in N2O emissions from central California

    NASA Astrophysics Data System (ADS)

    Jeong, Seongeun; Zhao, Chuanfeng; Andrews, Arlyn E.; Dlugokencky, Edward J.; Sweeney, Colm; Bianco, Laura; Wilczak, James M.; Fischer, Marc L.

    2012-08-01

    We estimate nitrous oxide (N2O) emissions from Central California for the period of December 2007 through November 2009 by comparing N2O mixing ratios measured at a tall tower (Walnut Grove, WGC) with transport model predictions based on two global a priori N2O emission models (EDGAR32 and EDGAR42). Atmospheric particle trajectories and surface footprints are computed using the Weather Research and Forecasting (WRF) and Stochastic Time-Inverted Lagrangian Transport (STILT) models. Regression analyses show that the slopes of predicted on measured N2O from both emission models are low, suggesting that actual N2O emissions are significantly higher than the EDGAR inventories for all seasons. Bayesian inverse analyses of regional N2O emissions show that posterior annual N2O emissions are larger than both EDGAR inventories by factors of 2.0 ± 0.4 (EDGAR32) and 2.1 ± 0.4 (EDGAR42) with seasonal variation ranging from 1.6 ± 0.3 to 2.5 ± 0.4 for an influence region of Central California within approximately 150 km of the tower. These results suggest that if the spatial distribution of N2O emissions in California follows the EDGAR emission models, then actual emissions are 2.7 ± 0.5 times greater than the current California emission inventory, and total N2O emissions account for 8.1 ± 1.4% of total greenhouse gas emissions from California.

  9. 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

  10. 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.

  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

    2015-01-01

    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

  12. 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

  13. Pathway of nitrous oxide consumption in isolated Pseudomonas stutzeri strains under anoxic and oxic conditions.

    PubMed

    Desloover, Joachim; Roobroeck, Dries; Heylen, Kim; Puig, Sebastià; Boeckx, Pascal; Verstraete, Willy; Boon, Nico

    2014-10-01

    The microbial consumption of nitrous oxide (N2O) has gained great interest since it was revealed that this process could mitigate the greenhouse effect of N2O. The consumption of N2O results from its reduction to dinitrogen gas (N2) as part of the denitrification process. However, there is ongoing debate regarding an alternative pathway, namely reduction of N2O to NH4(+), or assimilatory N2O consumption. To date, this pathway is poorly investigated and lacks unambiguous evidence. Enrichment of denitrifying activated sludge using a mineral nitrogen-free medium rendered a mixed culture capable of anoxic and oxic N2O consumption. Dilution plating, isolation and deoxyribonucleic acid fingerprinting identified a collection of Pseudomonas stutzeri strains as dominant N2O consumers in both anaerobic and aerobic enrichments. A detailed isotope tracing experiment with a Pseudomonas stutzeri isolate showed that consumption of N2O via assimilatory reduction to NH4(+) was absent. Conversely, respiratory N2O reduction was directly coupled to N2 fixation. PMID:24447520

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

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

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

  15. Nitrous oxide formation during nitritation and nitrification of high-strength wastewater.

    PubMed

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

    2013-01-01

    The purpose of this study was to investigate the formation of nitrous oxide (N2O) in nitritation and nitrification under stable, comparable and not limiting conditions typical for treatment of high-strength wastewater. A laboratory-scale aerated chemostat was operated with reject water at different sludge retention times, achieving suppression of nitrate formation by wash-out of nitrite-oxidizing bacteria for nitritation. The N2O formation factor during stable nitritation was higher (2.90% N2O-N /NH4(-)-Nox) than during nitrification (0.74%). The positive correlation of N2O formation rates and ammonium oxidation rates was linear and thus did not contribute to changes of the N2O formation factor. The dominant factor for N2O formation during stable operation was high nitrite concentration, which was positively correlated with N2O formation rates. The highest formation factors were observed during a transition phase from nitrification to nitritation with unstable process conditions (4.81%) and during a short-term experiment with increased pH of 7 (10.28%). The results indicate that even with operational conditions that are regarded favourable for the process of nitritation N2O formation can be limited but not avoided. PMID:23752381

  16. Cropping Sequence and Nitrogen Fertilization Effects on Dryland Soil Nitrous Oxide Emission

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Emission of nitrous oxide (N2O), a potent greenhouse gas responsible for global warming, may be influenced by cropping and N fertilization management. The effects of three cropping sequences [no-tilled continuous malt barley (NTCB), no-tilled malt barley-pea (NTB-P), and conventional tilled malt bar...

  17. Tillage and Inorganic Nitrogen Source Effects on Nitrous Oxide Emissions from Irrigated Cropping Systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) emissions were monitored from irrigated corn production systems receiving different N sources at fertilizer rates of 246 kg N ha-1 when in corn (Zea mays L.), 56 kg N ha-1 when in dry bean (Phaseolus vulgaris L.), and 157 kg N ha-1 when in barley (Hordeum distichon L.). Croppin...

  18. Nitrogen, Tillage, and Crop Rotation Effects on Nitrous Oxide Emissions from Irrigated Cropping Systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluated the effects of irrigated crop management practices on nitrous oxide (N2O) emissions. Emissions were monitored from several irrigated cropping systems receiving N fertilizer rates ranging from 0 to 246 kg N ha-1 during the 2005 and 2006 growing seasons. Cropping systems includ...

  19. 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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  1. 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...

  2. 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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  4. 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...

  5. 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 ...

  6. 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...

  7. Tillage and Fertilizer Effects on Soil Methane and Nitrous Oxide Emissions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural soil is a source of greenhouse gases such as methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2). An experiment was conducted to determine effects of tillage system, fertilizer type, and fertilizer application method on emissions of these three gases. Corn was grown on a silt...

  8. Nitrogen Source Affects Nitrous Oxide Emissions in a Strip-Tilled Continuous Corn Field

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the effects of nitrogen (N) source on nitrous oxide (N2O) emissions from a strip-till (ST), irrigated continuous corn field in 2009 near Fort Collins, CO. Emissions were monitored from plots receiving six different inorganic N fertilizer sources (urea, ESN®1, SuperU®, UAN, UAN+Agrotain...

  9. Nitrogen Source Affects Nitrous Oxide Emissions from Irrigated No-Till Corn in Colorado (USA)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction Nitrogen fertilization is essential for optimizing corn yields and economic returns in irrigated cropping systems in the USA Central Great Plains area (Maddux and Halvorson, 2008). However, N application generally increases nitrous oxide (N2O) emissions from cropping systems (Mosier et...

  10. 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 ...

  11. NITROGEN FERTILIZATION EFFECTS ON NITROUS OXIDE EMISSIONS FROM IRRIGATED CROPPING SYSTEMS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the effects of N fertilization and irrigated crop management practices on nitrous oxide (N2O) emissions. Emissions were monitored from several irrigated cropping systems receiving N fertilizer rates (0, 67, 134, and 246 kg N/ha) during the 2006 growing season and N rates of 0 and 246 ...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  13. Nitrous Oxide Production in an Eastern Corn Belt Soil: Sources and Redox Range

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) derived from soils is a main contributor to the greenhouse gas effect and a precursor to ozone-depleting substrates; however, the source processes and interacting controls are not well established. This study was conducted to estimate magnitude and source (nitrification vs. denit...

  14. 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...

  15. 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.

  16. Tropospheric N2O Isotopic Composition: Instrumentation Development and Initial Data for Reducing N2O Source and Sink Uncertainties

    NASA Astrophysics Data System (ADS)

    Potter, K. E.; Ono, S.; Greally, B.; Simmonds, P. G.; Young, D.; Prinn, R. G.

    2008-12-01

    Measurements of nitrous oxide isotopic composition in the troposphere provide a means for minimizing much of the uncertainty in the regional and global budgets of this important atmospheric species which arises predominately from biological sources in soils and oceans. Continuous atmospheric surface measurements of the concentration of N2O have provided an important resource in analysis of the budget through inversion studies. The utilization of these concentration data, however, has reached the limit of information that can be extracted about the N2O budget and leaves large uncertainty remaining. Combined with the isotopic signatures of N2O source and sink process end-members, isotopic N2O measurements in the troposphere will place added constraints on the budget. This research pursues N2O isotopomer analysis of tropospheric samples to trace the origin and fate of N2O in the atmosphere. Impediments regarding instrumentation have prevented pursuit of this line of research in the scientific community. Instrumentation developed by our group yields initial data for air samples from Boston, MA, which demonstrate the ability of N2O isotopic analysis to distinguish biospheric controls on N2O from stratosphere-troposphere exchange. Data from Boston are explored and applied alongside theoretical analysis of N2O isotopic composition in the troposphere to examine the ability of isotope data to lower uncertainty in particular related to the role of stratosphere-troposphere exchange, which is largely unknown in global budget estimates and forces uncertainty into current estimates of biosphere- atmosphere exchange.

  17. Industrial Sources of Nitrous Oxide, Methyl-Chloride and Methyl-Bromide

    NASA Astrophysics Data System (ADS)

    Hao, Wei Min

    The production of nitrous oxide in combustion of fossil fuels is studied in an experimental system and in effluent gases of power plants. The formation chemistry of N(,2)O in combustion is studied by using a kinetic model. Emissions of CH(,3)Cl and CH(,3)Br from automobiles are also investigated. Nitrous oxide was found to be generated in combustion of natural gas, No. 6 oil and coal-water slurry at the M.I.T. Combustion Research Facility. Distributions of N(,2)O along the flame axis are similar to those of NO(,x) under a variety of experimental conditions. The formation of N(,2)O is likely related to the production of NO(,x). Oxidation of nitrogen compounds in fossil fuels may be the major process producing N(,2)O in fuel oil and coal flames. Field studies of N(,2)O and NO(,x) emissions from power plants confirm the findings at the M.I.T. combustor. The emissions of N(,2)O and NO(,x) are linearly correlated. There is at least one N(,2)O molecule formed for every four NO(,x) produced. About 14% of the fuel-nitrogen is oxidized to N(,2)O. These results indicate that the increase of tropospheric N(,2)O for the last twenty years contains a large contribution due to combustion of fossil fuel. At the present time, one fourth of the annual N(,2)O production may be attributed to this source. Tropospheric N(,2)O concentrations may be expected to reach 380 ppb in 2050 given the current growth rate of world energy consumption. The kinetic model calculation identifies NCO + NO (--->) N(,2)O + CO as the key reaction for the formation of N(,2)O in oil and coal flames. Removal of N(,2)O is by reaction with hydrogen atoms. Emissions levels of CH(,3)Cl and CH(,3)Br from automobiles using leaded gasoline were found to decrease. As the driving speeds increase. Automobiles are not an important global source of atmospheric CH(,3)Cl and CH(,3)Br.

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

    PubMed Central

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

    2012-01-01

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

  19. 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. PMID:22296600

  20. Stratospheric & Tropospheric Production of Nitrous Oxide: New Insights

    NASA Astrophysics Data System (ADS)

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

    2001-12-01

    Nitrous oxide (N2O) is very important as a powerful greenhouse gas and the dominant source of stratospheric NO. Current uncertainties in its sources and sinks and the origin of its mass-independent isotopic enrichment warrant a discussion of a recent significant development. Since no production was seen by Estupinan et al (ESNW)1 in photolysis of O3/O2/N2 mixture at 532 nm, the excited O3 capable of forming N2O ({O3}N2O) in Zipf-Prasad (ZP)2 experiment is not produced in O(3P),O2 recombination. It is likely a minor byproduct (reaction (1a)) of the termolecular quenching of O(1D) by O2. O(1D)+ O2 + O2 -> {O3}N2O+ {O2}*#(1a) O(1D)+ O2 + O2 -> O3 (highly dissociative singlets)+ {O2}*#(1b) The rate coefficient, k1a, needed to model ZP's quantum yield (Φ )of N2O is ~ 4x10-33 cm-6 s-1. The reaction (1b) or its parallel O(1D) + N2 + O2 -> O3 (highly dissociated triplets) + N2 (R2) probably made a minor contribution to ZP's Φ since the lifetimes of the relevant excited O3 is < 1 ns. Reactions (1b) & (2) amount to termolecular quenching of O(1D) since excited singlet and triplet O3 dissociate.\\The Φ of N2O in ESNW and Maric & Burrows (MB)3 experiments with 266/254 nm via the "true" N2O, O(1D) association may have been even lower than 3x10-7. Due to the reactivity of highly stretched molecules, the third generation N2O ({N2O}**(3)) in the chain of events that produces N2O from the initial N2, O(1D) association may be prone to loss by O2 (via possible reaction {N2O}** + O2-> N2 + O3*) when n(O2) -> n(N2). Thus, the idea that almost all of N2O observed by ESNW & MB was due to excited O3 needs consideration. Their data suggest a smaller yield. \\ Possibly, valuable information about the origin and properties of excited O3 may be hidden under this difference. As the first step towards progress, we need to check if the differences in ZP's and ESNW's results can be narrowed by better experiments. ZP had used a spectrally coarse light source. ESNW got a larger yield of N2O than

  1. 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.

  2. 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.

  3. 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...

  4. Regional scale analysis of nitrous oxide emissions within the U.S. Corn Belt and the potential role of episodic hot spots

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) is a long-lived greenhouse gas that has the third largest radiative forcing on the Earth-Atmosphere system and has become the most important stratospheric ozone depleting substance of the 21st century. The rapid increase in N2O concentrations over the last century is primarily at...

  5. SLOW-RELEASE N FERTILIZER TO CONTROL SOIL NITROUS OXIDE LOSSES DUE TO SPATIAL AND CLIMATIC DIFFERENCES IN SOIL WATER CONTENT AND DRAINAGE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural soils are a major source of nitrous oxide (N2O) which contributes to global warming and ozone depletion. The objectives of this research were to establish the relationship between soil N2O flux, temperature, soil NO3--N, and soil water content and to compare the performance and cost-eff...

  6. Nitrous oxide accumulation in soils from riparian buffers of a coastal plain watershed carbon/nitrogen ratio control.

    PubMed

    Hunt, P G; Matheny, T A; Ro, K S

    2007-01-01

    Riparian buffers are used throughout the world for the protection of water bodies from nonpoint-source nitrogen pollution. Few studies of riparian or treatment wetland denitrification consider the production of nitrous oxide (N2O). The objectives of this research were to ascertain the level of potential N2O production in riparian buffers and identify controlling factors for N2O accumulations within riparian soils of an agricultural watershed in the southeastern Coastal Plain of the USA. Soil samples were obtained from ten sites (site types) with different agronomic management and landscape position. Denitrification enzyme activity (DEA) was measured by the acetylene inhibition method. Nitrous oxide accumulations were measured after incubation with and without acetylene (baseline N2O production). The mean DEA (with acetylene) was 59 microg N2O-N kg(-1) soil h(-1) for all soil samples from the watershed. If no acetylene was added to block conversion of N2O to N2, only 15 microg N2O-N kg(-1) soil h(-1) were accumulated. Half of the samples accumulated no N2O. The highest level of denitrification was found in the soil surface layers and in buffers impacted by either livestock waste or nitrogen from legume production. Nitrous oxide accumulations (with acetylene inhibition) were correlated to soil nitrogen (r2=0.59). Without acetylene inhibition, correlations with soil and site characteristics were lower. Nitrous oxide accumulations were found to be essentially zero, if the soil C/N ratios>25. Soil C/N ratios may be an easily measured and widely applicable parameter for identification of potential hot spots of N2O productions from riparian buffers. PMID:17636299

  7. Toxicity of methotrexate in rats preexposed to nitrous oxide.

    PubMed

    Ermens, A A; Schoester, M; Spijkers, L J; Lindemans, J; Abels, J

    1989-11-15

    Several chemotherapeutic protocols for the treatment of malignancies include administration of methotrexate (MTX) during or shortly after total anesthesia. Clinical observations in patients treated for breast carcinoma or childhood cancer have shown unexpected myelosuppression and mucosal damage. This phenomenon may be attributed to the synergistic effects of nitrous oxide, which inactivates the cobalamin coenzyme of methionine synthase, and MTX, which inhibits dihydrofolate reductase, on folate metabolism. However, no quantitative data on dose-effect relationships are available regarding the combined toxicity of MTX and N2O. We investigated the effect of exposure to N2O on the toxicity of MTX. Groups of male Wistar rats were exposed to either 50% N2O/50% O2 or air for 12-48 h. Subsequently, a single i.p. injection of 10, 20, 40, or 80 mg MTX/kg body weight was given. Gastrointestinal toxicity resulted in diarrhea and weight loss in all groups for 5 days after MTX administration. Concomitantly, bone marrow depression with leukocytopenia and thrombocytopenia occurred. Exposure to N2O did not alter the plasma clearance of MTX. No substantial liver or kidney toxicity could be detected, but the 50% lethal dose for MTX was reduced from 60 mg/kg to 10 mg/kg if rats had been exposed to N2O for 48 h; the main causes of death were dehydration and bleeding. The administration of 5-formyl-tetrahydrofolate (4 x 10 mg i.p.) but not 5-methyltetrahydrofolate protected completely against the lethal effect of the drug combination. Altogether, cytotoxic effects of MTX on proliferating cells are potentiated by N2O. Therefore, the use of this anesthetic shortly before or during MTX administration should be avoided. PMID:2804978

  8. 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

  9. Effect of temperature on anoxic metabolism of nitrites to nitrous oxide by polyphosphate accumulating organisms.

    PubMed

    Miao, Zhijia; Zeng, Wei; Wang, Shuying; Peng, Yongzhen; Cao, Guihua; Weng, Dongchen; Xue, Guisong; Yang, Qing

    2014-02-01

    Temperature is an important physical factor, which strongly influences biomass and metabolic activity. In this study, the effects of temperature on the anoxic metabolism of nitrite (NO2(-)) to nitrous oxide (N2O) by polyphosphate accumulating organisms, and the process of the accumulation of N2O (during nitrite reduction), which acts as an electron acceptor, were investigated using 91% +/- 4% Candidatus Accumulibacter phosphatis sludge. The results showed that N2O is accumulated when Accumulibacter first utilize nitrite instead of oxygen as the sole electron acceptor during the denitrifying phosphorus removal process. Properties such as nitrite reduction rate, phosphorus uptake rate, N2O reduction rate, and polyhydroxyalkanoate degradation rate were all influenced by temperature variation (over the range from 10 to 30 degrees C reaching maximum values at 25 degrees C). The reduction rate of N2O by N2O reductase was more sensitive to temperature when N2O was utilized as the sole electron acceptor instead of N2O, and the N2O reduction rates, ranging from 0.48 to 3.53 N20-N/(hr x g VSS), increased to 1.45 to 8.60 mg N2O-N/(hr x g VSS). The kinetics processes for temperature variation of 10 to 30 degrees C were (theta1 = 1.140-1.216 and theta2 = 1.139-1.167). In the range of 10 degrees C to 30 degrees C, almost all of the anoxic stoichiometry was sensitive to temperature changes. In addition, a rise in N2O reduction activity leading to a decrease in N2O accumulation in long term operations at the optimal temperature (27 degrees C calculated by the Arrhenius model). PMID:25076517

  10. 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

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

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

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

  12. 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.

  13. 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

  14. Measurement of Electron Swarm Parameters in Nitrous Oxide

    NASA Astrophysics Data System (ADS)

    Deng, Yunkun; Xiao, Dengming; Li, Xuewen; Gao, Xiaofei

    2013-05-01

    This study has measured the density-normalized effective ionization coefficients (α-η)/N, the electron drift velocity Ve and the diffusion coefficient DL in nitrous oxide (N2O) using a pulsed Townsend technique. The range of the overall density-normalized electric field strength E/N is from 100 Td to 400 Td (1 Td=10-17 V·cm2). From the above plots of (α-η)/N, we have derived the limiting field strength, (E/N)lim ≈ 150 Td, which is the value of E/N at which (α-η)/N = 0.

  15. 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

  16. 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. PMID:22967492

  17. 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.

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

    PubMed

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

    2015-12-01

    The effects of dissolved oxygen (DO) and pH on nitrous oxide (N2O) production rates and pathways in autotrophic partial nitrification (PN) granules were investigated at the granular level. N2O was primarily produced by betaproteobacterial ammonia-oxidizing bacteria, mainly Nitrosomonas europaea, in the oxic surface layer (<200μm) of the autotrophic PN granules. N2O production increased with increasing bulk DO concentration owing to activation of the ammonia (i.e., hydroxylamine) oxidation in this layer. The highest N2O emissions were observed at pH 7.5, although the ammonia oxidation rate was unchanged between pH 6.5 and 8.5. Overall, the results of this study suggest that in situ analyses of PN granules are essential to gaining insight into N2O emission mechanisms in a granule. PMID:26318242

  19. Effect of biochar on nitrous oxide emission and its potential mechanisms.

    PubMed

    Liu, Liang; Shen, Guoqing; Sun, Mingxing; Cao, Xinde; Shang, Guofeng; Chen, Ping

    2014-08-01

    Extensive use of biochar to mitigate nitrous oxide (N2O) emission is limited by the lack of understanding on the exact mechanisms altering N2O emission from biochar-amended soil. Biochars produced from rice straw and dairy manure at 350 and 500 degrees C by oxygen-limited pyrolysis were used to investigate their influence on N2O emission. A quadratic effect of biochar levels was observed on the N2O emissions. The potential mechanisms were explored by terminal restriction fragment length polymorphism (T-RFLP) and real-time polymerase chain reaction (qPCR). A lower relative abundance of bacteria, which included ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), was observed at 4% biochar application rate. Reduced copy numbers of the ammonia monooxygenase gene amoA and the nitrite reductase gene nirS coincided with decreased N2O emissions. Therefore, biochar may potentially alter N2O emission by affecting ammonia-oxidizing and denitrification bacteria, which is determined by the application rate of biochar in soil. Implications: Biochar research has received increased interest in recent years because of the potential beneficial effects of biochar on soil properties. Recent research shows that biochar can alter the rates of nitrogen cycling in soil systems by influencing nitrification and denitrification, which are key sources of the greenhouse gas nitrous oxide (N2O). However, there are still some controversial data. The purpose of this research was to (1) examine how applications of different dose of biochar to soil affect emission of N2O and (2) improve the understanding of the underlying mechanisms. PMID:25185392

  20. 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

  1. 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

  2. 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

  3. 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.

  4. Agricultural management and environment controls long-term soil nitrous oxide fluxes

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Nitrous oxide (N2O) is an important greenhouse gas with a long atmospheric half-life. Understanding the controls on soil nitrous oxide fluxes is vital for the development of mitigation opportunities and for understanding their climatic impact. The spatial and temporal variability of soil nitrous oxide fluxes, however, makes it difficult to predict such fluxes. We examined the longest available dataset, 22 years of continues measurements, which contains biweekly measurements of soil nitrous oxide emissions together with measurements of an array of environmental and management parameters from eleven ecosystems, including four corn-soybean-wheat rotations under different management (conventional, no-till, biological, and reduced input), one perennial alfalfa system, two tree plantations, three successional systems, and one deciduous forest. This dataset was used to assess the effect of different agricultural and land management practices on soil N2O emissions. Using statistical and correlation analyses, we found that, in general, annual crops emitted 2-3 times more N2O annually than did perennial crops. Among the annual crops, there were no differences in the annual emissions among the cropping systems; the conventional, no-till, reduced input, and biologically managed systems emitted similar amounts of N2O with very different emission patterns. Among the perennial crops, alfalfa emitted 2 times more N2O than did poplar, approximately 1.6 times more than did the coniferous plantation, and ~3 times more than did the unmanaged successional communities and the deciduous forest, which emitted similar amounts. Within the annual crop rotation phases, the wheat phase of the conventionally and no-till-managed rotations emitted approximately twice as much N2O than did the reduced input- and biologically managed systems, largely due to the length of the bare soil fallow. The corn and soybean phases of the conventionally managed rotation emitted between 70 and 100% less N2O than

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

    PubMed

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

    2016-01-01

    Nitrous oxide (N2O) is an important greenhouse gas (GHG) with substantial global warming potential and also contributes to ozone depletion through photochemical nitric oxide (NO) production in the stratosphere. The negative effects of N2O on climate and stratospheric ozone make N2O mitigation an international challenge. More than 60% of global N2O emissions are emitted from agricultural soils mainly due to the application of synthetic nitrogen-containing fertilizers. Thus, mitigation strategies must be developed which increase (or at least do not negatively impact) on agricultural efficiency whilst decrease the levels of N2O released. This aim is particularly important in the context of the ever expanding population and subsequent increased burden on the food chain. More than two-thirds of N2O emissions from soils can be attributed to bacterial and fungal denitrification and nitrification processes. In ammonia-oxidizing bacteria, N2O is formed through the oxidation of hydroxylamine to nitrite. In denitrifiers, nitrate is reduced to N2 via nitrite, NO and N2O production. In addition to denitrification, respiratory nitrate ammonification (also termed dissimilatory nitrate reduction to ammonium) is another important nitrate-reducing mechanism in soil, responsible for the loss of nitrate and production of N2O from reduction of NO that is formed as a by-product of the reduction process. This review will synthesize our current understanding of the environmental, regulatory and biochemical control of N2O emissions by nitrate-reducing bacteria and point to new solutions for agricultural GHG mitigation. PMID:27134026

  6. 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.

  7. 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.

  8. 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. PMID:15307074

  9. 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.

  10. [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

  11. 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

  12. The tropical Atlantic Ocean as a Source of atmospheric Nitrous Oxide

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

    Nitrous oxide (N2O) was measured as part of the first German SOLAS (Surface Ocean - Lower Atmosphere Study) cruise M55 from Willemstad (Curacao, Netherl. Antilles) to Douala (Cameroon) on board R/V Meteor from 12 Oct to 17 Nov 2002. About 950 atmospheric and dissolved N2O measurements were preformed with a continuous-working GC-ECD system equipped with a Weiss-type seawater-gas equilibrator. Surface waters along the main transect at 10°N showed no distinct longitudinal gradient. Instead, N2O saturations were highly variable ranging from 96% (e.g. at 10°N, 45°W) to 120% (e.g. in the Guinea Dome Area, 10°N, 20°W). N2O concentrations in the northernmost boundary of the Amazon outflow were close to equilibrium values. When approaching the continental shelf of West Africa, surface waters N2O saturations were continuously supersaturated (up to 15%). N2O saturations in the region of the equatorial upwelling (at 1.5 0°N, 26 23.5° W) were correlated with lower sea surface temperatures and showed saturations up to 110%. The overall mean N2O saturation was 104 ± 2 % indicating that the tropical Atlantic Ocean is only a weak source of atmospheric N2O.

  13. 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

  14. [Nitrous oxide emission during denitrification for activated sludge acclimated with methanol as the organic carbon].

    PubMed

    Zhai, Xiao-Feng; Jiang, Cheng-Ai; Wu, Guang-Xue; Guan, Yun-Tao

    2013-04-01

    Denitrification of wastewater is one of the important sources of nitrous oxide (N2O). In this study, denitrifies were acclimated in a sequencing batch reactor with methanol and nitrate (NO3(-) -N) as the electron donor and acceptor, respectively. N2O emission during denitrification was examined both in typical cycles and in batch experiments under conditions of different electron acceptors, carbon/nitrogen (C/N) ratios and initial nitrite (NO2(-)-N) concentrations. With methanol as the organic carbon, the N2O emission was high with NO2(-)-N as the electron acceptor and the N2O emission was low with NO3(-) -N as the electron acceptor. The C/N ratios affected the emission of N2O by affecting activities of denitrifiers, and both the activity of denitrifiers and the emission of N2O decreased with decreasing C/N ratios. The N2O emission increased with increasing initial NO2(-) -N concentrations, and a certain range of NO2(-) -N concentrations enhanced the activity of denitrifiers. The N2O emission could be correlated very well with initial NO2(-) -N concentrations. PMID:23798124

  15. Influence of operating conditions on nitrous oxide formation during nitritation and nitrification.

    PubMed

    Schneider, Y; Beier, M; Rosenwinkel, K-H

    2014-10-01

    Nitrous oxide (N2O), a strong greenhouse gas, can be produced by ammonium-oxidizing bacteria (AOB) as a by-product of ammonium oxidation and can potentially be formed in all types of nitrification processes. However, partial nitritation has been reported to cause significantly higher N2O emissions than complete nitrification. In the study presented here, the mechanisms and factors that drive N2O formation by AOB were investigated with respect to different operational strategies to achieve nitrite accumulation base on combined evaluation of oxygen uptake rate (OUR) and N2O formation rate. On the one hand, N2O formation during partial nitritation and nitrification in a continuously stirred tank reactor (CSTR) with continuous aerobic conditions was observed. On the other hand, the effect of intermittent aeration on N2O formation during nitrification was investigated. The presence of nitrite, the extend of sludge-specific ammonium loading, low oxygen concentration, and transition from aerobic to anoxic conditions significantly increased N2O formation in this reactor independently from each other, indicating that different formation pathways, supposedly via nitrite or hydroxylamine, were active. PMID:24928380

  16. Identification of key nitrous oxide production pathways in aerobic partial nitrifying granules.

    PubMed

    Ishii, Satoshi; Song, Yanjun; Rathnayake, Lashitha; Tumendelger, Azzaya; Satoh, Hisashi; Toyoda, Sakae; Yoshida, Naohiro; Okabe, Satoshi

    2014-10-01

    The identification of the key nitrous oxide (N2O) production pathways is important to establish a strategy to mitigate N2O emission. In this study, we combined real-time gas-monitoring analysis, (15)N stable isotope analysis, denitrification functional gene transcriptome analysis and microscale N2O concentration measurements to identify the main N2O producers in a partial nitrification (PN) aerobic granule reactor, which was fed with ammonium and acetate. Our results suggest that heterotrophic denitrification was the main contributor to N2O production in our PN aerobic granule reactor. The heterotrophic denitrifiers were probably related to Rhodocyclales bacteria, although different types of bacteria were active in the initial and latter stages of the PN reaction cycles, most likely in response to the presence of acetate. Hydroxylamine oxidation and nitrifier denitrification occurred, but their contribution to N2O emission was relatively small (20-30%) compared with heterotrophic denitrification. Our approach can be useful to quantitatively examine the relative contributions of the three pathways (hydroxylamine oxidation, nitrifier denitrification and heterotrophic denitrification) to N2O emission in mixed microbial populations. PMID:24650173

  17. Biologically produced volatile compounds: N2O emissions from the soil and the N2O global budget

    NASA Technical Reports Server (NTRS)

    Banin, A.; Whitten, R.; Livingston, G.; Lawless, J.

    1985-01-01

    N2O dynamics were studied at the soil-atmosphere interface and their effects on the global N2O budget. Troposphere nitrous oxide (N2O) concentration has increased by 0.2 to 0.4 pct. per year over the period 1975 to 1982, amounting to a net addition to the atmosphere of 2.8 to 5.6 Tg N2O-N per year. This perturbation, if continued into the future, will affect stratospheric chemical cycles, and the thermal balance of the Earth. In turn it will have direct and indirect global effects on the biosphere. The only well documented heat sinks identified to date are the stratospheric photolytic decomposition processes. However, quantitatively, they do not account for all the known sources. Emission from soils is the least understood and most variable component in the N2O budget. An automated field station that will measure N2O fluxes and interchanges over long periods of time is being developed. At each station, the source/sink relations of N2O at the soil-atmosphere interface will be measured and their relations to environmental conditions are documented and quantified. The results from the perennial measurements will generate the data base on which global budgets for N2O will be constructed and related to ecosystem parameters.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  19. 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

  20. Historical mining of soil nitrogen was a likely source of atmospheric nitrous oxide

    NASA Astrophysics Data System (ADS)

    Davidson, E. A.

    2009-12-01

    Prior to the advent of use of synthetic nitrogen (N) fertilizers, agricultural expansion was often followed by depletion of soil carbon and N stocks. While the mining of soil N permits a period of productive agriculture, it may also result in transfers of soil N to groundwater, surface water, and the atmosphere. Atmospheric nitrous oxide (N2O) concentrations have been increasing since the industrial revolution and currently account for 6% of total anthropogenic radiative forcing. Microbial production in soils is the dominant N2O source. The use of synthetic N fertilizers alone cannot account for the historical trends of atmospheric concentrations of N2O, because the increase in atmospheric N2O began well before N fertilizers were widely used. Here, I analyze atmospheric concentrations, industrial sources of N2O, and fertilizer and manure production since 1860. Prior to 1960, agricultural expansion, including livestock production, appears to have caused globally significant mining of soil N, fuelling a steady increase in atmospheric N2O. Post 1960, the rate of the increase rose, due to accelerating use of synthetic N fertilizers. Using a regression model, I show that 2% of manure N and 2.5% of fertilizer N were converted to N2O between 1860 and 2005; these percentage contributions explain the entire pattern of increasing N2O concentrations over this period. Consideration of processes that re-concentrate soil N, such as manure production by livestock, improved hind-casting of N2O emissions. Any process in the past, present, or future that causes either accumulation or depletion of N reservoirs in soils or sediments could affect N2O emissions. As animal protein consumption in human diets increases globally, management of manure will be an important component of future mitigation efforts to reduce anthropogenic N2O sources.

  1. 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

  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. 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.

  4. 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

  5. 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.

  6. 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

  7. 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

  8. 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

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

    PubMed

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

    2015-06-28

    We present an analytical intermolecular potential energy surface (PES) for two rigid nitrous oxide (N2O) molecules derived from high-level quantum-chemical ab initio calculations. Interaction energies for 2018 N2O-N2O configurations were computed utilizing the counterpoise-corrected supermolecular approach at the CCSD(T) level of theory using basis sets up to aug-cc-pVQZ supplemented with bond functions. A site-site potential function with seven sites per N2O molecule was fitted to the pair interaction energies. We validated our PES by computing the second virial coefficient as well as shear viscosity and thermal conductivity in the dilute-gas limit. The values of these properties are substantiated by the best experimental data. PMID:26133428

  10. 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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  12. 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

  13. 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.

  14. Exposure of anesthesiologists to nitrous oxide during pediatric anesthesia.

    PubMed

    Chang, W P; Kau, C W; Hseu, S S

    1997-01-01

    Nitrous oxide (N2O) is one of the most common inhalation anesthetics in current anesthesiological practice. Even though artificial ventilation and active scavenging in operating theaters are employed in most of the modern hospitals, potential N2O contamination persists in regular anesthesia, particularly pediatric operation. In order to understand personal exposure during pediatric anesthesia, ambient monitoring for N2O exposure around the breathing zone of the anesthesiologist was conducted by a portable infra-red Miran 1B2 spectrophotometer. The results demonstrated that general mask anesthesia generated greatest N2O contamination, with the mean time-weighted-average (TWA) concentrations of 85 +/- 48.4 (mean +/- S.D.) ppm in 12 cases. Initial mask induction followed by cuffed endotracheal incubation (6 cases) or intravenous induction followed by uncuffed endotracheal intubation (6 cases) also produced significant pollution to the workers, with the mean TWAs of 33.2 +/- 24.0 ppm and 31.9 +/- 18.0 ppm respectively. These procedures provided exposure levels above the 25 ppm Recommended Exposure Limit (REL) of the National Institute of Occupational Safety and Health (NIOSH), U.S.A. Modification with intravenous induction followed with cuffed endotracheal intubation or mask general anesthesia provided with a ventilation hood diminished the contamination apparently, with the resulting mean TWAs of 11.0 +/- 4.7 ppm and 17.9 +/- 9.8 ppm in 7 and 5 cases respectively. The results indicated that excessive N2O exposure to anesthesiologists was not negligible during routine pediatric anesthesia. Significant reduction could be achieved via appropriate industrial modification. PMID:9009509

  15. Indian methane and nitrous oxide emissions and mitigation flexibility

    NASA Astrophysics Data System (ADS)

    Garg, Amit; Shukla, P. R.; Kapshe, Manmohan; Menon, Deepa

    Methane (CH 4) and nitrous oxide (N 2O) contributed 27% and 7%, respectively, to India's CO 2 equivalent greenhouse gas (GHG) emissions in 2000, the remaining being the carbon dioxide (CO 2) emissions. Presently, agriculture and livestock related emissions contribute above 65% of Indian CH 4 emissions and above 90% of N 2O emissions. Since these activities are widely dispersed, with a considerable portion being sub-sustenance activities, emission mitigation requires considerable efforts. We use geographical information system (GIS) interfaced Asia-Pacific Integrated Model (AIM/Enduse), which employs technology share projections, for estimating future CH 4 and N 2O emissions. The future emissions and mitigation flexibility are analyzed for a reference scenario and two mitigation scenarios (medium and strong). Future CH 4 emissions in 2030 are projected to reach 24.4 Tg (reference scenario), 21.3 Tg (medium mitigation scenario) and 17.6 Tg (strong mitigation scenario). Future CH 4 emission scenarios indicate rising shares of municipal solid waste (MSW) and coal bed methane, where mitigation technologies have good penetration potential. Improved cattle feed and digesters, and better rice paddy cultivation practices that are adopted for higher yields and improved irrigation coverage also offer CH 4 mitigation as ancillary benefits. Future N 2O emissions in 2030 are projected to reach 0.81 Tg (reference scenario), 0.69 Tg (medium mitigation scenario) and 0.6 Tg (strong mitigation scenario). Better utilization of nitrogen fertilizer and increased use of organic fertilizers, partly produced from MSW, offer interesting mitigation opportunities for N 2O emissions. Some of these technology initiatives are already visible in India at different stages of development and appropriate policy thrust may strengthen them in future.

  16. 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.

  17. 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

  18. 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.

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

    PubMed

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

    2015-01-01

    Using a culture-based nitrous oxide (N2O) emission assay, three active N2O emitters were isolated from Sphagnum fuscum leaves and all identified as members of Burkholderia. These isolates showed N2O emission in the medium supplemented with [Formula: see text] but not with [Formula: see text], and Burkholderia sp. SF-E2 showed the most efficient N2O emission (0.20 μg·vial(-1)·day(-1)) at 1.0 mM KNO3. In Burkholderia sp. SF-E2, the optimum pH for N2O production was 5.0, close to that of the phyllosphere of Sphagnum mosses, while the optimum temperature was uniquely over 30 °C. The stimulating effect of additional 1.5 mM sucrose on N2O emission was ignorable, but Burkholderia sp. SF-E2 upon exposure to 100 mg·L(-1) E-caffeic acid showed uniquely 67-fold higher N2O emission. All of the three N2O emitters were negative in both acetylene inhibition assay and PCR assay for nosZ-detection, suggesting that N2O reductase or the gene itself is missing in the N2O-emitting Burkholderia. PMID:26167675

  20. Transport coefficients and cross sections for electrons in N2O and N2O/N2 mixtures

    NASA Astrophysics Data System (ADS)

    Dupljanin, S.; de Urquijo, J.; Šašić, O.; Basurto, E.; Juárez, A. M.; Hernández-Ávila, J. L.; Dujko, S.; Petrović, Z. Lj

    2010-04-01

    A standard swarm analysis of electron scattering cross sections in nitrous oxide (N2O) is presented. The experimental results for drift velocities and effective ionization coefficients (differences between the ionization and attachment coefficients), obtained over an extended range of E/N (electric field normalized to the gas number density) by the pulsed-Townsend technique, are compared with the numerical solution of the Boltzmann equation. Our analysis shows that commonly used sets of cross sections have to be modified in order to fit the new experimental data, in particular the dissociative cross sections for attachment and electronic excitation (with a threshold energy of around 4.0 eV). Using a single set of cross sections it was possible to fit both the data for pure N2O and those for the N2O/N2 mixtures with 20%, 40%, 60% and 80% N2O.

  1. 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

  2. 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. PMID:24513304

  3. Relative rates of nitric oxide and nitrous oxide production by nitrifiers, denitrifiers, and nitrate respirers.

    PubMed

    Anderson, I C; Levine, J S

    1986-05-01

    Biogenic emissions of nitric and nitrous oxides have important impacts on the photochemistry and chemistry of the atmosphere. Although biogenic production appears to be the overwhelming source of N(2)O, the magnitude of the biogenic emission of NO is very uncertain. In soils, possible sources of NO and N(2)O include nitrification by autotrophic and heterotrophic nitrifiers, denitrification by nitrifiers and denitrifiers, nitrate respiration by fermenters, and chemodenitrification. The availability of oxygen determines to a large extent the relative activities of these various groups of organisms. To better understand this influence, we investigated the effect of the partial pressure of oxygen (pO(2)) on the production of NO and N(2)O by a wide variety of common soil nitrifying, denitrifying, and nitrate-respiring bacteria under laboratory conditions. The production of NO per cell was highest by autotrophic nitrifiers and was independent of pO(2) in the range tested (0.5 to 10%), whereas N(2)O production was inversely proportional to pO(2). Nitrous oxide production was highest in the denitrifier Pseudomonas fluorescens, but only under anaerobic conditions. The molar ratio of NO/N(2)O produced was usually greater than unity for nitrifiers and much less than unity for denitrifiers. Chemodenitrification was the major source of both the NO and N(2)O produced by the nitrate respirer Serratia marcescens. Chemodenitrification was also a possible source of NO and N(2)O in nitrifier cultures but only when high concentrations of nitrite had accumulated or were added to the medium. Although most of the denitrifiers produced NO and N(2)O only under anaerobic conditions, chemostat cultures of Alcaligenes faecalis continued to emit these gases even when the cultures were sparged with air. Based upon these results, we predict that aerobic soils are primary sources of NO and that N(2)O is produced only when there is sufficient soil moisture to provide the anaerobic microsites

  4. Novel microelectrode-based online system for monitoring N2O gas emissions during wastewater treatment.

    PubMed

    Marques, Ricardo; Oehmen, Adrian; Pijuan, Maite

    2014-11-01

    Clark-type nitrous oxide (N2O) microelectrodes are commonly used for measuring dissolved N2O levels, but have not previously been tested for gas-phase applications, where the N2O emitted from wastewater systems can be directly quantified. In this study, N2O microelectrodes were tested and validated for online gas measurements, and assessed with respect to their temperature, gas flow, composition dependence, gas pressure, and humidity. An exponential correlation between temperature and sensor signal was found, whereas gas flow, composition, pressure, and humidity did not have any influence on the signal. Two of the sensors were tested at different N2O concentration ranges (0-422.3, 0-50, 0-10, and 0-2 ppmv N2O) and exhibited a linear response over each range. The N2O emission dynamics from two laboratory scale sequencing batch reactors performing ammonia or nitrite oxidation were also monitored using one of the microsensors and results were compared with two other analytical methods. Results show that N2O emissions were accurately described with these microelectrodes and support their application for assessing gaseous N2O emissions from wastewater treatment systems. Advantages of the sensors as compared to conventional measurement techniques include a wider quantification range of N2O fluxes, and a single measurement system that can assess both liquid and gas-phase N2O dynamics. PMID:25317738

  5. The Oxygen Isotopic Signature of Nitrous Oxide is Determined by Oxygen Exchange

    NASA Astrophysics Data System (ADS)

    Kool, D. M.; Wrage, N.; Oenema, O.; Harris, D.; van Groenigen, J.

    2008-12-01

    In order to derive accurate budget estimations and effective mitigation strategies for the greenhouse gas nitrous oxide (N2O), it is essential to identify the processes involved in its production. Analyses of the isotopic composition of N2O are increasingly used to characterize the importance of these processes. However, we argue that the reliability of results based on oxygen (O) isotopic analysis of N2O may be questioned due to insufficient consideration of O exchange between H2O and nitrogen oxides. We studied the process of O exchange in 12 widely varying soils using a novel combination of 18O and 15N tracing experiments. Incorporation of O from 18O-enriched H2O into N2O exceeded theoretical maxima based on reaction stoichiometry, revealing the presence of O exchange. Novel methodology based on the retention of the 18O:15N-enrichment ratio of NO3- in N2O allowed to quantify O exchange during denitrification: up to 97% of N2O-O originated from H2O instead of NO3-. Our results show that in soil, the main source of N2O, the conventional assumption that the O isotopic composition of N2O is determined by reaction stoichiometry and isotopic fractionation during its production does not hold. In all cases, the O isotopic signature of N2O was found to be dominated by the effect of O exchange between nitrogen oxides and water. We speculate that the implications of O exchange will extend across terrestrial and aquatic ecosystems, and possibly to other nitrogen oxides as well. Especially, a potential effect of O exchange on the O isotopic signature of NO3- needs to be studied, as this is routinely used for NO3- source determination. Our results may facilitate the development of improved methodology to study and understand the global N cycle.

  6. 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

  7. 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. PMID:22629611

  8. Model of the molecular basis for hydroxylamine oxidation and nitrous oxide production in methanotrophic bacteria.

    PubMed

    Campbell, Mark A; Nyerges, Györgyi; Kozlowski, Jessica A; Poret-Peterson, Amisha T; Stein, Lisa Y; Klotz, Martin G

    2011-09-01

    Many methane-oxidizing bacteria (MOB) have been shown to aerobically oxidize ammonia and hydroxylamine (NH(2)OH) to produce nitrite and nitrous oxide (N(2)O). Genome sequences of alphaproteobacterial, gammaproteobacterial, and verrucomicrobial methanotrophs revealed the presence of haoAB, cytL, cytS, nirS or nirK, and norCB genes that may be responsible for N(2)O production, and additional haoAB genes were sequenced from two strains of Methylomicrobium album. The haoAB genes of M. album ATCC 33003 were inducible by ammonia and NH(2)OH, similar to haoAB induction by ammonia in Methylococcus capsulatus Bath. Increased expression of genes encoding nitric oxide reductase (cNOR; norCB) was measured upon exposure of M. capsulatus Bath to NaNO(2) and NO-releasing sodium nitroprusside. Only incubations of M. capsulatus Bath with methane, ammonia, and nitrite produced N(2)O. The data suggest a possible pathway of nitrite reduction to NO by reversely operating NH(2)OH oxidoreductase and NO reduction to N(2)O by cNOR independently or in conjunction with ammonia-induced enzymes (i.e. HAO or cytochrome c'-β). Results of this study show that MOB likely have diverse mechanisms for nitrogen oxide metabolism and detoxification of NH(2)OH that involve conventional and unconventional enzymes. PMID:21682764

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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.

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

    PubMed

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

    2016-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Spokas, K.; Wang, D.

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

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. Determination of the nitrous oxide emission potential of deammonification under anoxic conditions.

    PubMed

    Schneider, Y; Beier, M; Rosenwinkel, K-H

    2011-12-01

    Various studies have been performed to determine nitrous oxide (N2O) emissions from conventional biological nitrogen removal processes in wastewater treatment like nitrification and denitrification in the main stream. However, with respect to the overall emissions of a wastewater treatment plant, part-stream treatment for high-strength wastewater (e.g., sludge liquor) is also expected to hold a significant emission potential because of high concentrations and extreme boundary conditions. This paper presents results from a laboratory-scale study on nitrous oxide production by biomass from a deammonification process (nitritation + anammox) under anoxic conditions. It was discovered that N2O formation results from incomplete endogenous denitrification rather than anammox and is dependent on substrate availability. Based on direct measurements of the dissolved N2O concentrations in a sequencing batch reactor, the dynamic behavior of N2O production is characterized in more detail. The results show that, during anoxic conditions, the N2O emission potential of deammonification is significantly lower than from conventional denitrification. PMID:22368962

  1. 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

  2. Nitrous oxide emissions from an ultisol of the humid tropics under maize-groundnut rotation.

    PubMed

    Khalil, M I; Rosenani, A B; Van Cleemput, O; Fauziah, C I; Shamshuddin, J

    2002-01-01

    Nitrous oxide (N20) contributes to global climate change and agricultural soils seem to be the major source. Lack of information led to this study on the influence of different amounts and sources of nitrogen on N2O emission from a maize (Zea mays L.)-groundnut (Arachis hypogae L.) crop rotation in an Ultisol of the humid tropics. The treatments were: inorganic N + crop residues (NC), inorganic N only (RN), and half of inorganic N + crop residues + chicken manure (NCM). The corresponding amount of N applied was 322, 180, and 400 kg ha(-1) yr(-1), respectively. The N2O emissions depended on the amounts and types of N. A maximum peak (9,889 +/- 2,106 microg N2O-N m(-2) d(-1)) was detected at 2 wk before maize sowing amended with chicken manure, showing a persistent influence on N transformations and N2O release. The mineral N from either applied source became low by 2 to 4 wk, coinciding with the small N2O fluxes or its consumption to a few isolated instances. The N2O flux significantly correlated with the mineral N and water-filled pore spaces. The direct annual N2O emission was 3.94 +/- 0.23, 1.90 +/- 0.08, and 1.41 +/- 0.07 kg N2O-N ha(-1) from the NCM, NC, and RN treatments, respectively. The corresponding N2O-N loss of the applied N plus N fixed by groundnut was 0.83, 0.49, and 0.59%. Overestimations of direct annual N2O emission using the Intergovernmental Panel on Climate Change (IPCC) methodology suggest a location-specific emission factor for variable N sources to be considered. PMID:12175023

  3. Evaluating the Impact of Changes in Oceanic Dissolved Oxygen on Marine Nitrous Oxide

    NASA Astrophysics Data System (ADS)

    Suntharalingam, Parvadha; Buitenhuis, Erik; Schmidtko, Sunke; Andrews, Oliver; LeQuere, Corinne

    2013-04-01

    Emissions of the greenhouse gas nitrous-oxide (N2O) from oceanic oxygen minimum zones (OMZs) in the Equatorial Pacific and Northwest Indian Ocean are believed to provide a significant portion of the global oceanic flux to the atmosphere. Mechanisms of marine N2O production and consumption in these regions display significant sensitivity to ambient oxygen, with high yields at low oxygen levels (O2 < 50 micromol/L), and N2O depletion via denitrification in anoxic zones. These OMZ regions display large gradients in sub-surface N2O, and high rates of N2O turnover that far exceed those observed in the open ocean. Recent studies have suggested that possible expansion of oceanic OMZs in a warming climate, could lead to significant changes in N2O emissions from these zones. In this analysis we employ a global ocean biogeochemistry model (NEMO-PlankTOM), which includes representation of the marine N2O cycle, to explore the impact of changes in dissolved oxygen on the ocean-atmosphere N2O flux. We focus on the period 1960-2000, and evaluate the impact of estimated changes in ocean oxygen from two alternative sources : (a) the observationally-based upper-ocean oxygen distributions and trends of Stramma et al. [2012]; (b) simulated oxygen distributions and temporal variations from a set of CMIP5 Earth System models. We will inter-compare the oceanic N2O estimates derived from these alternative scenarios of ocean de-oxygenation. We will also discuss the implications of our results for the ability to reliably predict changes in N2O emissions under potential expansion of oceanic OMZs, particularly in view of the recently noted discrepancies between observed and modeled trends in oceanic oxygen by Stramma et al. [2012].

  4. 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.

  5. Global Measurement of Nitrous Oxide Stable Isotopes Using Cavity Ring-Down Spectroscopy

    NASA Astrophysics Data System (ADS)

    Steiker, A. E.; Townsend, A. R.; White, J. W. C.

    2014-12-01

    Nitrous oxide continues to increase in the atmosphere mainly due to heightened microbial production from fertilized agricultural systems. Soil microorganism processes are spatiotemporally heterogeneous, limiting our ability to constrain the anthropogenic influence on N2O production at a global scale. The intramolecular position of 15N (β position 15N14N16O versus α position 14N15N16O) in addition to δ15Nbulk-N2O can aid in our understanding of both the biological controls and stratospheric influence of tropospheric N2O. A subset of 22 sites from the NOAA Global Monitoring Division Cooperative Sampling Network is being measured in order to describe the global distribution and seasonality of N2O isotopocules. Simultaneous and continuous measurement of N2O mole fraction, δ15Nbulk-N2O, δ15Nα-N2O, and δ15Nβ-N2O is conducted using the Picarro G5101-i wavelength-scanned cavity ring-down spectrometer coupled with a quantum cascade laser capable of the mid-infrared wavelength detection needed for N2O. While isotopic differences within and between sites are observed, long term measurement uncertainties of 0.7‰, 0.8‰, and 1.3‰ for δ15Nbulk, δ15Nα, and δ15Nβ respectively, limit our ability to detect tropospheric trends. Applying additional correction factors for environmental conditions and molecular interference may help to reduce these uncertainties. Due to the lack of isotopic reference material for N2O, we have developed an isotopic calibration technique using trace additions of δ15Nα and δ15Nβ to our reference gas at the ambient mole fraction needed for laser based isotopic measurement.

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

    PubMed Central

    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

  7. 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.

  8. 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

  9. 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.

  10. 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

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

    DOE PAGESBeta

    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.

  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. 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

  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. PMID:25079265

  15. 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

  16. Minimization of nitrous oxide emission in a pilot-scale oxidation ditch: generation, spatial variation and microbial interpretation.

    PubMed

    Zheng, Maosheng; Tian, Yuhao; Liu, Tang; Ma, Tao; Li, Li; Li, Can; Ahmad, Muhammad; Chen, Qian; Ni, Jinren

    2015-03-01

    Nitrous oxide (N2O) emission from wastewater treatment plants (WWTPs) has received increasing attention. This paper presented how N2O emission was significantly reduced in a pilot-scale Carrousel oxidation ditch under reasonable nitrification and denitrification. N2O emission from the reactor was found as low as 0.027% of influent nitrogen, which was much less than that from other processes. Further measurements on spatial variation of N2O emission in the alternative aerobic/anoxic zones with help of a series of batch experiments demonstrated that about 90% of the emission was contributed by nitrifier denitrification (ND). Moreover, the taxonomic analysis based on high through-put 16S rRNA gene sequencing revealed that the high abundance of denitrifying bacteria and nitrite-oxidizing bacteria (NOB) was responsible for low nitrite accumulations and consequent low N2O emissions. However, N2O generation would be greatly increased upon the normal operation being shocked by either ammonia overload or aeration failure of the oxidation ditch system. PMID:25575212

  17. 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

  18. 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

  19. 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.

  20. 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

  1. 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. PMID:26760756

  2. 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.

  3. 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

  4. 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

  5. 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

  6. 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.

  7. Nitrous oxide production and consumption: regulation of gene expression by gas-sensitive transcription factors

    PubMed Central

    Spiro, Stephen

    2012-01-01

    Several biochemical mechanisms contribute to the biological generation of nitrous oxide (N2O). N2O generating enzymes include the respiratory nitric oxide (NO) reductase, an enzyme from the flavo-diiron family, and flavohaemoglobin. On the other hand, there is only one enzyme that is known to use N2O as a substrate, which is the respiratory N2O reductase typically found in bacteria capable of denitrification (the respiratory reduction of nitrate and nitrite to dinitrogen). This article will briefly review the properties of the enzymes that make and consume N2O, together with the accessory proteins that have roles in the assembly and maturation of those enzymes. The expression of the genes encoding the enzymes that produce and consume N2O is regulated by environmental signals (typically oxygen and NO) acting through regulatory proteins, which, either directly or indirectly, control the frequency of transcription initiation. The roles and mechanisms of these proteins, and the structures of the regulatory networks in which they participate will also be reviewed. PMID:22451107

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. Polymer-Coated Urea Maintains Potato Yields and Reduces Nitrous Oxide Emissions in a Minnesota Loamy Sand

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Large inputs of nitrogen (N) fertilizer required for crops such as potatoes have the potential to generate soil-to-atmosphere emissions of nitrous oxide (N2O), which is a potent greenhouse gas. Coated urea fertilizer products are designed to better match N supply to plant uptake and thereby minimize...

  13. Nitrogen source effects on nitrous oxide emissions from irrigated strip-till and no-till corn production ystems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrogen (N) source and placement effects on soil nitrous oxide (N2O) emissions from strip-till (ST) and no-till (NT), irrigated continuous corn fields were evaluated in 2011 near Fort Collins, CO on a clay loam soil. Emissions were monitored from plots receiving urea, ESN®1, SuperU®, and liquid UA...

  14. 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...

  15. Discerning agricultural management effects on nitrous oxide emissions from conventional and alternative cropping systems: A California case study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several decades of research have provided crucial understanding of the production of nitrous oxide (N2O) from agricultural soils and the major environmental and managerial factors that play a role in the evolution of this potent greenhouse gas (GHG). The increase in demands for food production and ...

  16. CARBON DIOXIDE AND NITROUS OXIDE FLUXES IN ORGANIC, NO-TILL AND CHISEL-TILL CROPPING SYSTEMS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Organic cropping systems may have the potential to increase soil C sequestration and reduce soil nitrous oxide (N2O) fluxes compared to conventional systems but organic systems are not well studied. We are measuring greenhouse gas fluxes and soil C sequestration in no-till, chisel-till and organic ...

  17. DEVELOPMENT OF SAMPLING AND ANALYTICAL METHODS FOR THE MEASUREMENT OF NITROUS OXIDE FROM FOSSIL FUEL COMBUSTION SOURCES

    EPA Science Inventory

    The report documents the technical approach and results achieved while developing a grab sampling method and an automated, on-line gas chromatography method suitable to characterize nitrous oxide (N2O) emissions from fossil fuel combustion sources. he two methods developed have b...

  18. Emissions of Ammonia, Methane, Carbon Dioxide and Nitrous Oxide From Dairy Cattle Housing and Manure Management Systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Concentrated animal feeding operations emit trace gases such as ammonia (NH3), methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) to the atmosphere. The implementation of air quality regulations in livestock-producing states increases the need for accurate on-farm determination of emissio...

  19. Seasonal variation of N2O emissions in France inferred from atmospheric N2O and 222Rn measurements

    NASA Astrophysics Data System (ADS)

    Lopez, M.; Schmidt, M.; Yver, C.; Messager, C.; Worthy, D.; Kazan, V.; Ramonet, M.; Bousquet, P.; Ciais, P.

    2012-07-01

    Nitrous oxide (N2O) concentrations and 222Rn activities are measured semi-continuously at three stations in France: Gif-sur-Yvette (a semi-urban station near Paris), Trainou tower (a rural station) and Puy-de-Dôme (a mountain site). From 2002 to 2011, we have found a mean rate of N2O increase of 0.7 pbb a-1. The analysis of the mean diurnal N2O and 222Rn cycles shows maximum variabilities at the semi-urban site of Gif-sur-Yvette (0.96 ppb for N2O and 2 Bq m-3 for 222Rn) compared to the rural site of Trainou tower (0.32 ppb for N2O and 1.3 Bq m-3 for 222Rn). The use of 222Rn as a tracer for vertical mixing and atmospheric transport, combined with the semi-continuous N2O measurements, allows estimation of N2O emissions by applying the Radon-Tracer-Method. Mean N2O emissions values between 0.34 ± 0.12 and 0.51 ± 0.18 g(N2O) m-2 a-1 and 0.52 ± 0.18 g(N2O) m-2 a-1were estimated in the catchment area of Gif-sur-Yvette and Trainou, respectively. The mean annual N2O fluxes at Gif-sur-Yvette station correlate well with annual precipitation. A 25% increase in precipitation corresponds to a 32% increase in N2O flux. The N2O fluxes calculated with the Radon-Tracer-Method show a seasonal cycle, which indicates a strong contribution from the agricultural source, with the application of fertilizers in the early spring inducing a strong increase in N2O emissions. Finally, the results of the Radon-Tracer-Method agree well with the national and global emission inventories, accounting for the uncertainties of both methods.

  20. 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

  1. Study on the N2O Formation under Low Temperature Condition in Pulverized Biomass Combustion

    NASA Astrophysics Data System (ADS)

    Okumura, Yukihiko; Watanabe, Hirotatsu; Okazaki, Ken

    The purpose of this study is to clarify the fundamental and general features of N2O formation during the combustion of pulverized biomass under low temperature. First, the effect of various important factors, i.e., combustion temperature, volatilization process (i.e., either slow or rapid dispersion), and nitrogen content in biomass on N2O formation were investigated by theoretical analysis. The analysis of the effect of combustion temperature on the formation of nitrous oxide showed that N2O emission level increases with the decrease in combustion temperature, and both N2O and NO levels are strongly dependent on the combustion temperature. In other words, there is a trade-off relationship between the formation of NO and that of N2O. The analysis of the effect of the slow/rapid volatilization process on the formation of nitrous oxide showed that the conversion ratio of biomass-N to N2O increases with the decrease in the dispersion of volatile matter per unit time; it means that biomass-N is effectively converted to N2O during slow volatilization. Further, the gasification reactions between CO2, O2, and C occur simultaneously on the surface of biomass particles during combustion. With respect to the effect of nitrogen content in biomass, the N2O emission level increases with the increase in N-content of the biomass, while the NO emission level remains constant during low-temperature combustion.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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. PMID:21327481

  7. 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.

  8. Global observation of nitrous oxide: changes in growth rate and spatial patterns

    NASA Astrophysics Data System (ADS)

    Hall, B. D.; Dlugokencky, E. J.; Dutton, G. S.; Nance, J. D.; Crotwell, A. M.; Mondeel, D. J.; Elkins, J. W.

    2015-12-01

    Nitrous oxide (N2O) currently exerts the third largest climate forcing of the long-lived greenhouse gases, after CO2 and CH4. N2O is also involved in the destruction of stratospheric ozone. It is produced by microbial activity in soils and oceans, and also by industry. The atmospheric burden of N2O has increased more than 20% from its preindustrial level of ~270 nmol mol-1 (ppb). Much of this increase is related to the application of nitrogen-containing fertilizers, including manure. The NOAA Global Monitoring Division has measured the atmospheric mole fraction of N2O at Earth's surface in air samples collected around the globe (since the late 1970s) and at in situ sites mostly in the Western Hemisphere (since 1998). ). Measurements of the global burden and growth rate constrain global emissions, e.g. 18.2 ± 2.7 Tg N yr-1 in 2013, where most of the uncertainty is related to uncertainty in the global lifetime. The average growth rate of N2O from 1990 to 2010 was ~0.75 ppb yr-1. Since 2004, however, the growth rate has been increasing, and is now about 25% higher than the 1990-2010 average. Between 2010 and 2013 the growth rate averaged ~0.95 ppb yr-1. As the growth rate increased from 2004-2013, gradients derived from surface, zonal-mean N2O mole fraction, such the mean pole-to-pole difference, and the difference between NH temperate latitudes and the southern polar region, decreased. This suggests a change in the distribution of N2O emissions over this period. We will present our N2O data and examine trends, gradients, and other features that could shed light on recent changes in the growth rate. We will also compare N2O gradients to those of other trace gases, such as SF6.

  9. 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.

  10. 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.

  11. 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">

  12. 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

  13. Soil fluxes of methane, nitrous oxide, and nitric oxide from aggrading forests in coastal Oregon

    USGS Publications Warehouse

    Erickson, Heather E.; Perakis, Steven S.

    2014-01-01

    Soil exchanges of greenhouse and other gases are poorly known for Pacific Northwest forests where gradients in nutrient availability and soil moisture may contribute to large variations in fluxes. Here we report fluxes of methane (CH4), nitrous oxide (N2O), and nitric oxide (NO) over multiple seasons from three naturally N-rich, aggrading forests of coastal Oregon, USA. Mean methane uptake rates (3.2 mg CH4 m−2 d−1) were high compared with forests globally, negatively related to water-filled pore space (WFPS), but unrelated to N availability or temperature. Emissions of NO (6.0 μg NO–N m−2 h−1) exceeded N2O (1.4 μg N2O–N m−2 h−1), except when WFPS surpassed 55%. Spatial variation in NO fluxes correlated positively with soil nitrate concentrations (which generally exceeded ammonium concentrations, indicating the overall high N status for the sites) and negatively with soil pH, and at one site increased with basal area of N2-fixing red alder. Combined NO and N2O emissions were greatest from the site with highest annual net N mineralization and lowest needle litterfall C/N. Our findings of high CH4 uptake and NO/N2O ratios generally >1 most likely reflect the high porosity of the andic soils underlying the widespread regenerating forests in this seasonally wet region.

  14. Effect of process parameters and operational mode on nitrous oxide emissions from a nitritation reactor treating reject wastewater.

    PubMed

    Pijuan, Maite; Torà, Josep; Rodríguez-Caballero, Adrián; César, Elvira; Carrera, Julián; Pérez, Julio

    2014-02-01

    Nitrous oxide (N2O) and methane emissions were monitored in a continuous granular airlift nitritation reactor from ammonium-rich wastewater (reject wastewater). N2O emissions were found to be dependent on dissolved oxygen (DO) concentration in the range of 1-4.5 mg O2/L, increasing within this range when reducing the DO values. At higher DO concentrations, N2O emissions remained constant at 2.2% of the N oxidized to nitrite, suggesting two different mechanisms behind N2O production, one dependent and one independent of DO concentration. Changes on ammonium, nitrite, free ammonia and free nitrous acid concentrations did not have an effect on N2O emissions within the concentration range tested. When operating the reactor in a sequencing batch mode under high DO concentration (>5 mg O2/L), N2O emissions increased one order of magnitude reaching values of 19.3 ± 7.5% of the N oxidized. Moreover, CH4 emissions detected were due to the stripping of the soluble CH4 that remained dissolved in the reject wastewater after anaerobic digestion. Finally, an economical and carbon footprint assessment of a theoretical scaled up of the pilot plant was conducted. PMID:24316179

  15. Additional fluorine passivation to pyrolytic-N2O passivated ultrathin silicon oxide/Si(100) films

    NASA Astrophysics Data System (ADS)

    Yamada, Hiroshi

    2006-08-01

    To enhance the reliability of ultrathin silicon oxide/Si(100) films and clarify the effect of fluorine on it, in situ pyrolytic-gas passivation (PGP) using NF3 was simultaneously performed with the previously proposed PGP using N2O. As a result, the following synergistic effects of F and N passivation for the films were confirmed: The electrical characteristics, such as the time-dependent dielectric breakdown lifetime, potential barrier height energy of the oxide, and interface state density, were significantly improved. Quantitative analyses of F and N indicated that this is probably caused by microscopic structural changes in the oxide near the oxide-Si(100) substrate interface. It is, therefore, believed that F passivation effectively contributes to compensate the inconsistent-state bonding sites near the interface that remain with N passivation.

  16. 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

  17. 21 CFR 868.1700 - Nitrous oxide gas analyzer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nitrous oxide gas analyzer. 868.1700 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1700 Nitrous oxide gas analyzer. (a) Identification. A nitrous oxide gas analyzer is a device intended to measure the concentration of nitrous...

  18. 21 CFR 868.1700 - Nitrous oxide gas analyzer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nitrous oxide gas analyzer. 868.1700 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1700 Nitrous oxide gas analyzer. (a) Identification. A nitrous oxide gas analyzer is a device intended to measure the concentration of nitrous...

  19. Nitrous Oxide and Methane Fluxes Following Ammonium Sulfate and Vinasse Application on Sugar Cane Soil.

    PubMed

    Paredes, Debora da S; Alves, Bruno J R; dos Santos, Marco A; Bolonhezi, Denizart; Sant'Anna, Selenobaldo A C; Urquiaga, Segundo; Lima, Magda A; Boddey, Robert M

    2015-09-15

    This study aimed to quantify nitrous oxide (N2O) and methane (CH4) emission/sink response from sugar cane soil treated with fertilizer nitrogen (N) and vinasse applied separately or in sequence, the latter being investigated with regard to the time interval between applications for a possible effect on emissions. The study was carried out in a traditional area of unburned sugar cane in São Paulo state, Brazil. Two levels of N fertilization (0 and 100 kg N ha(-1)) with no added vinasse and combined with vinasse additions at different times (100 m(-3) ha(-1) at 3 and 15 days after N fertilization) were evaluated. Methane and N2O fluxes were monitored for 211 days. On average, the soil was a sink for CH4, which was not affected by the treatments. Emissions of N2O were induced by N fertilizer and vinasse applications. For ammonium sulfate, 0.6% of the added N was emitted as N2O, while for vinasse, this ranged from 1.0 to 2.2%. Changes in N2O fluxes were detected the day after application of vinasse on the N fertilized areas, but although the emission factor (EF) was 34% greater, the EF was not significantly different from fertilizer N alone. Nevertheless, we recommend to not apply vinasse after N fertilization to avoid boosting N2O emissions. PMID:26295867

  20. Factors controlling nitrous oxide emissions from a full-scale activated sludge system in the tropics.

    PubMed

    Brotto, Ariane C; Kligerman, Débora C; Andrade, Samara A; Ribeiro, Renato P; Oliveira, Jaime L M; Chandran, Kartik; de Mello, William Z

    2015-08-01

    Despite interest in characterizing nitrous oxide (N2O) emissions from wastewater treatment plants (WWTPs) in several parts of the globe, there are few studies in tropical zones. This study focus on the contribution of the scientific knowledge of anthropogenic nitrogen greenhouse gas emissions to climate change in tropical countries, investigating factors controlling N2O emissions in a non-biological nitrogen removal municipal WWTP. In terms of operational parameters, dissolved oxygen (DO) concentrations displayed a biphasic impact on N2O production and emission, with the highest emission at DO of 2.0 mg O2 L(-1). The low solids retention time of 3 days also played a significant role, leading to nitrite accumulation, which is an important trigger for N2O production during nitrification. Furthermore, other factor especially important for tropical countries, namely, temperature, also had a positive correlation with N2O production. Emission factors estimated for this study were 0.12 (0.02-0.31)% of the influent total nitrogen load and 8.1 (3-17) g N2O person(-1) year(-1), 2.5 times higher than currently proposed emission factors. Therefore, the highly variability and dependence on operational parameters reinforce the use of a single emission factor is inadequate, especially for developing countries with limited or variable extent of biological wastewater treatment and in regions of the world with widely varying climate patterns. PMID:25860552

  1. Mitigating Nitrous Oxide Emissions from Tea Field Soil Using Bioaugmentation with a Trichoderma viride Biofertilizer

    PubMed Central

    Xu, Shengjun; Fu, Xiaoqing; Ma, Shuanglong; Xiao, Runlin; Li, Yong; Zhuang, Guoqiang

    2014-01-01

    Land-use conversion from woodlands to tea fields in subtropical areas of central China leads to increased nitrous oxide (N2O) emissions, partly due to increased nitrogen fertilizer use. A field investigation of N2O using a static closed chamber-gas chromatography revealed that the average N2O fluxes in tea fields with 225 kg N ha−1 yr−1 fertilizer application were 9.4 ± 6.2 times higher than those of woodlands. Accordingly, it is urgent to develop practices for mitigating N2O emissions from tea fields. By liquid-state fermentation of sweet potato starch wastewater and solid-state fermentation of paddy straw with application of Trichoderma viride, we provided the tea plantation with biofertilizer containing 2.4 t C ha−1 and 58.7 kg N ha−1. Compared to use of synthetic N fertilizer, use of biofertilizer at 225 kg N ha−1 yr−1 significantly reduced N2O emissions by 33.3%–71.8% and increased the tea yield by 16.2%–62.2%. Therefore, the process of bioconversion/bioaugmentation tested in this study was found to be a cost-effective and feasible approach to reducing N2O emissions and can be considered the best management practice for tea fields. PMID:24955418

  2. Iron: The Forgotten Driver of Nitrous Oxide Production in Agricultural Soil

    PubMed Central

    Zhu, Xia; Silva, Lucas C. R.; Doane, Timothy A.; Horwath, William R.

    2013-01-01

    In response to rising interest over the years, many experiments and several models have been devised to understand emission of nitrous oxide (N2O) from agricultural soils. Notably absent from almost all of this discussion is iron, even though its role in both chemical and biochemical reactions that generate N2O was recognized well before research on N2O emission began to accelerate. We revisited iron by exploring its importance alongside other soil properties commonly believed to control N2O production in agricultural systems. A set of soils from California's main agricultural regions was used to observe N2O emission under conditions representative of typical field scenarios. Results of multivariate analysis showed that in five of the twelve different conditions studied, iron ranked higher than any other intrinsic soil property in explaining observed emissions across soils. Upcoming studies stand to gain valuable information by considering iron among the drivers of N2O emission, expanding the current framework to include coupling between biotic and abiotic reactions. PMID:23555906

  3. Adducts of nitrous oxide and N-heterocyclic carbenes: syntheses, structures, and reactivity.

    PubMed

    Tskhovrebov, Alexander G; Vuichoud, Basile; Solari, Euro; Scopelliti, Rosario; Severin, Kay

    2013-06-26

    N-Heterocyclic carbenes (NHCs) react at ambient conditions with nitrous oxide to give covalent adducts. In the crystal, all compounds show a bent N2O group connected via the N-atom to the former carbene carbon atom. Most adducts are stable at room temperature, but heating induces decomposition into the corresponding ureas. Kinetic experiments show that the thermal stability of the NHC-N2O adducts depends on steric as well as electronic effects. The coordination of N2O to NHCs weakens the N-N bond substantially, and facile N-N bond rupture was observed in reactions with acid or acetyl chloride. On the other hand, reaction with tritylium tetrafluoroborate resulted in a covalent modification of the terminal O-atom, and cleavage of the C-N2O bond was observed in a reaction with thionyl chloride. The coordination chemistry of IMes-N2O (IMes = 1,3-dimesitylimidazol-2-ylidene) was explored in reactions with the complexes CuOTf, Fe(OTf)2, PhSnCl3, CuCl2, and Zn(C6F5)2. Structural analyses show that IMes-N2O is able to act as a N-donor, as an O-donor, or as a chelating N,O-donor. The different coordination modes go along with pronounced electronic changes as evidenced by a bond length analysis. PMID:23758062

  4. Potential of nitrous oxide recovery from an aerobic/oxic/anoxic SBR process.

    PubMed

    Zhao, Jianqiang; Huang, Nan; Hu, Bo; Jia, Luwei; Ge, Guanghuan

    2016-01-01

    A single sequencing batch reactor (SBR) with an operating mode of anaerobic/oxic/anoxic (A/O/A) was developed to determine a simpler process to recover nitrous oxide (N2O) from synthetic wastewater containing ammonia and glucose. This SBR system was initiated in A/O mode to implement nitritation (ammonia to nitrite) and then switched to A/O/A mode. Using measurements of the dissolved N2O concentration and release rate, the total production and conversion rate of N2O were calculated to reveal the potential of producing and recovering N2O in the extended anoxic phase. Results showed that the A/O/A SBR could convert the majority of the nitrite available in the system into N2O by heterotrophic denitritation over longer anoxic periods, and a conversion rate of 77% could be achieved. As a consequence, the A/O/A SBR presents potential ability to produce and recover N2O from wastewater containing ammonia and organic carbon. PMID:26942527

  5. 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.

  6. 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

  7. 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

  8. Nitrous oxide emission from an agricultural field fertilized with liquid lagoonal swine effluent

    NASA Astrophysics Data System (ADS)

    Whalen, S. C.; Phillips, R. L.; Fischer, E. N.

    2000-06-01

    Contemporary agriculture is characterized by the intensive production of livestock in confined facilities and land application of stored waste as an organic fertilizer. Emission of nitrous oxide (N2O) from receiving soils is an important but poorly constrained term in the atmospheric N2O budget. In particular, there are few data for N2O emissions from spray fields associated with industrial scale swine production facilities that have rapidly expanded in the southeastern United States. In an intensive, 24-day investigation over three spray cycles, we followed the time course for changes in N2O emission and soil physicochemical variables in an agricultural field irrigated with liquid lagoonal swine effluent. The total N (535 mg L-1) of the liquid waste was almost entirely NH4+-N (>90%) and thus had a low mineralization potential. Soil profiles for nitrification and denitrification indicated that >90% of potential activity was localized in the surface 20 cm. Application of this liquid fertilizer to warm (19° to 28°C) soils in a form that is both readily volatilized and immediately utilizable by the endogenous N-cycling microbial community resulted in a sharp decline in soil NH4+-N and supported a rapid but short-lived (i.e., days) burst of nitrification, denitrification, and N2O emission. Nitrous oxide fluxes as high as 9200 μg N2O-N m-2 h-1 were observed shortly after fertilization, but emissions decreased to prefertilization levels within a few days. Poor correlations between N2O efflux and soil physicochemical variables (temperature, moisture, NO3--N, NH4+-N) and fertilizer loading rate point to the complexity of interacting factors affecting N2O production and emission. Total fertilizer N applied and N2O-N emitted were 29.7 g m-2 (297 kg N ha-1) and 395 mg m-2, respectively. The fractional loss of applied N to N2O (corrected for background emission) was 1.4%, in agreement with the mean of 1.25% reported for mineral fertilizers. The direct effects of fertilizer

  9. Isotopomers as a method for differentiating between bacterial and fungal production of nitrous oxide

    NASA Astrophysics Data System (ADS)

    Sutka, R. L.; Adams, G.; Ostrom, N.; Ostrom, P.

    2007-12-01

    In order to study the importance of fungi to nitrous oxide (N2O) production in the environment it is critical to have a non-intrusive method for differentiating between fungal and bacterial N2O production. Site preference (SP), the difference in d15N between the central and outer N atoms in N2O, has been used to differentiate between bacterial nitrification and denitrification. In this study we compare the SP, d15N and d18O of N2O produced by the two best-studied fungal denitrifiers, Fusarium oxysporum and Cylindrocarpon tonkinense, to data from our previous bacterial studies. Both d18O and SP values remained fairly constant during the course of nitrite reduction which likely reflects isotopic exchange with water in the case of d18O and conservative behavior in SP that has been observed previously (Sutka et al., 2006). We observed a wide range of fractionation factors for fungal denitrification, -74.7 to -6.6 ‰, and non-linear behavior indicating that fractionation was controlled by more than one step. We interpret the small degree of fractionation as reflecting fractionation during diffusion and the more negative values as being controlled by enzymatic fractionation. Data from this and our previous study of bacterial production (Sutka et al., 2006) reveals that N2O produced via nitrification by fungi can be differentiated from N2O produced by bacterial denitrification primarily on the basis of d18O. The site preference of N2O produced by F. oxysporum and C. tonkinense was 37.1 ± 2.5 ‰ and 36.9 ± 2.8 ‰, respectively. These results indicate that isotopomers can be used as a basis for differentiating bacterial and fungal denitrification. Our work further reveals the role that fungal and bacterial nitric oxide reductases have in determining site preference during N2O production.

  10. 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.

  11. A compact QCL based methane and nitrous oxide sensor for environmental and medical applications.

    PubMed

    Jahjah, Mohammad; Ren, Wei; Stefański, Przemysław; Lewicki, Rafał; Zhang, Jiawei; Jiang, Wenzhe; Tarka, Jan; Tittel, Frank K

    2014-05-01

    A methane (CH4) and nitrous oxide (N2O) sensor based on a sensitive, selective and well established technique of quartz enhanced photoacoustic spectroscopy (QEPAS) was developed for environmental and biomedical measurements. A thermoelectrically cooled (TEC) distributed feedback quantum cascade laser (DFB-QCL), capable of continuous wave (CW) mode hop free emission in the 7.83 μm wavelength range, was used as an excitation source. For the targeted CH4 and N2O absorption lines located at 1275.04 cm(-1) and 1275.49 cm(-1) detection limits (1σ) of 13 ppbv and 6 ppbv were achieved with a 1 second data acquisition time, respectively. Environmental data of CH4 and N2O mixing ratios acquired using the QEPAS sensor system are also reported. PMID:24427770

  12. Nitrous oxide production in soils and the ratio of the fungal to bacterial biomass

    NASA Astrophysics Data System (ADS)

    Blagodatskiy, S. A.; Avksent'ev, A. A.; Davydova, M. A.; Blagodatskaya, E. V.; Kurakov, A. V.

    2008-12-01

    The proportion between the fungal and bacterial biomass, the potential activity of denitrification, and the intensity of N2O production were determined in the soils (chernozem and soddy-podzolic) of secondary biocenoses formed upon the abandoning of agricultural lands. The substitution of meadow and forest vegetation for agrocenoses has led to an increase in the percentage of the fungal biomass in the upper soil horizons. The rate of the net N2O production after the soil moistening positively correlated with the content of nitrates. In the soddy-podzolic soil (pH 3.7-5.6), the rate of nitrous oxide production was higher than that in the chernozem (pH 6.1-6.8). The rate of N2O production was inversely proportional to the bacterial biomass in the soils.

  13. Relative rates of nitric oxide and nitrous oxide production by nitrifiers, denitrifiers, and nitrate respirers

    NASA Technical Reports Server (NTRS)

    Anderson, I. C.; Levine, J. S.

    1986-01-01

    An account is given of the atmospheric chemical and photochemical effects of biogenic nitric and nitrous oxide emissions. The magnitude of the biogenic emission of NO is noted to remain uncertain. Possible soil sources of NO and N2O encompass nitrification by autotropic and heterotropic nitrifiers, denitrification by nitrifiers and denitrifiers, nitrate respiration by fermenters, and chemodenitrification. Oxygen availability is the primary determinant of these organisms' relative rates of activity. The characteristics of this major influence are presently investigated in light of the effect of oxygen partial pressure on NO and N2O production by a wide variety of common soil-nitrifying, denitrifying, and nitrate-respiring bacteria under laboratory conditions. The results obtained indicate that aerobic soils are primary sources only when there is sufficient moisture to furnish anaerobic microsites for denitrification.

  14. Nitrous oxide flux and nitrogen transformations across a landscape gradient in Amazonia

    NASA Technical Reports Server (NTRS)

    Livingston, Gerald P.; Vitousek, Peter M.; Matson, Pamela A.

    1988-01-01

    Nitrous oxide flux and nitrogen turnover were measured in three types of Amazonian forest ecosystems within Reserva Florestal Ducke near Manaus, Brazil. Nitrogen mineralization and nitrate production measured during 10-day laboratory incubations were 3-4 times higher in clay soils associated with 'terra firme' forests on ridge-top and slope positions than in 'campinarana' forests on bottomland sand soils. In contrast, nitrous oxide fluxes did not differ significantly among sites, but were highly variable in space and time. The observed frequency distribution of flux was positively skewed, with a mean overall sites and all sampling times of 1.3 ng N2O-N/sq cm per hr. Overall, the flux estimates were comparable to or greater than those of temperature forests, but less than others reported for Amazoonia. Results from a field fertilization experiment suggest that most nitrous oxide flux was associated with denitrification of soil nitrate.

  15. Oxidation of phenyl and hydride ligands of bis(pentamethylcyclopentadienyl)hafnium derivatives by nitrous oxide via selective oxygen atom transfer reactions: insights from quantum chemistry calculations.

    PubMed

    Xie, Hujun; Liu, Chengcheng; Yuan, Ying; Zhou, Tao; Fan, Ting; Lei, Qunfang; Fang, Wenjun

    2016-01-21

    The mechanisms for the oxidation of phenyl and hydride ligands of bis(pentamethylcyclopentadienyl)hafnium derivatives (Cp* = η(5)-C5Me5) by nitrous oxide via selective oxygen atom transfer reactions have been systematically studied by means of density functional theory (DFT) calculations. On the basis of the calculations, we investigated the original mechanism proposed by Hillhouse and co-workers for the activation of N2O. The calculations showed that the complex with an initial O-coordination of N2O to the coordinatively unsaturated Hf center is not a local minimum. Then we proposed a new reaction mechanism to investigate how N2O is activated and why N2O selectively oxidize phenyl and hydride ligands of . Frontier molecular orbital theory analysis indicates that N2O is activated by nucleophilic attack by the phenyl or hydride ligand. Present calculations provide new insights into the activation of N2O involving the direct oxygen atom transfer from nitrous oxide to metal-ligand bonds instead of the generally observed oxygen abstraction reaction to generate metal-oxo species. PMID:26660046

  16. Termite mounds as hot spots of nitrous oxide emissions in South-Sudanian savanna of Burkina Faso (West Africa)

    NASA Astrophysics Data System (ADS)

    Brümmer, Christian; Papen, Hans; Wassmann, Reiner; Brüggemann, Nicolas

    2009-05-01

    Despite a considerable knowledge of the significant role of termites in the global methane budget, very little is known about their contribution to the global nitrous oxide (N2O) budget. Release of N2O from termite (Cubitermes fungifaber) mounds was measured at a natural savanna site in the southwest of Burkina Faso from May to September 2006. Termite N2O emissions were around 20 μg N2O-N m-2 h-1 at the end of the dry season, and up to two orders of magnitude higher than N2O emissions from the surrounding termite-free soil after the onset of the rainy season. The average N2O emission rate from termite mounds during the observation period was 204 μg N2O-N m-2 h-1, and termite mounds contributed 3.0% to total N2O emissions from this savanna ecosystem. However, in other tropical terrestrial ecosystems with other termite species and/or higher termite density this share might be significantly higher.

  17. Implication of Land Use and Belowground Weather on Nitrous Oxide Soil Depth Profiles and Denitrification Potential

    NASA Astrophysics Data System (ADS)

    Phillips, R. L.; Song, B.; Saliendra, N.; Liebig, M. A.

    2013-12-01

    Agricultural soils are the largest single source of anthropogenic nitrous oxide (N2O) to the atmosphere, which is largely attributed to the expansion in the use of synthetic fertilizer nitrogen (N). Alfalfa crops often do not require synthetic N addition because N is fixed symbiotically belowground. Some biologically fixed N leaks into soil, which could affect production and consumption of N2O. While many studies have reported net fluxes of N2O at the soil surface, few have quantified variation in N2O concentration at multiple soil depths under variable climatic conditions without synthetic N inputs. A no-till crop field, seeded to alfalfa (Medicago sativa) in 2009, was compared to neighboring native prairie in North Dakota, U.S.A. to determine if N2O, CO2 and CH4 concentrations varied with depth between fields for 4 years. Both fields (> 15 ha) were harvested for hay without N-fertilizer inputs between 2009 and 2013. Soils and instrumentation were similar. Sensors and soil gas well collection chambers were buried at near-surface (15 and 30 cm) and sub-surface (60 and 90 cm) soil depths. Temperature, moisture, oxygen, relative humidity, and pressure data were collected every 30 minutes, and gas well concentration data were collected twice weekly until spring 2013. Cores were collected for each depth increment in 2012, and potential rates of denitrification and anammox were measured for the 0-15 cm depth using soil slurry incubation experiments with 15N tracer treatments. We evaluated temporal variability in N2O concentration with depth and found N2O spikes beneath alfalfa tended to be an order of magnitude higher and more persistent than N2O peaks beneath prairie. Median N2O concentrations at sub-surface depths were greater than near-surface depths. Alfalfa median N2O concentrations for near-surface (24 nmols N2O L-1) and sub-soils (30 nmols N2O L-1) were higher than N2O concentrations beneath prairie (15 nmols N2O L-1 and 17 nmols N2O L-1, respectively). Soil

  18. Nitrous oxide in coastal waters

    SciTech Connect

    Bange, H.W.; Rapsomanikis, S.; Andreae, M.O.

    1996-03-01

    Measurements of dissolved and atmospheric nitrous oxide (N{sub 2}O) are presented for three coastal environments: (1) the central North Sea, (2) the German Bight, and (3) the Gironde estuary. The contribution of coastal regions to the oceanic emissions of atmospheric N{sub 2}O were also determined. N{sub 2}O was measured with a gas chromatograph equipped with an electron capture detector and analyzed. The surface waters of the central North Sea and the German bight were found to be near equilibrium with the overlying atmosphere, while the mean saturation in the Gironde estuary was 132%. Mean saturations in coastal regions without estuaries or upwelling phenomena were only slightly higher than in the open ocean. When estuaries and regions with upwelling are included, however, approximately 60% of the oceanic N{sub 2}O flux is attributable to coastal regions. A review of published data indicated that previous studies have seriously underestimated N{sub 2}O sea-to-air flux from coastal regions. 69 refs., 8 figs., 4 tabs.

  19. Impact of Cover Cropping and Landscape Positions on Nitrous Oxide Emissions in Northeastern Agroecosystems

    NASA Astrophysics Data System (ADS)

    Han, Z.; Walter, M. T.; Drinkwater, L. E.

    2015-12-01

    Studies investigating agricultural nitrous oxide (N2O) emissions tend to rely on plot-scale experiments. However, to understand the impacts of agricultural practices at a larger scale, it is essential to consider the variability of landscape characteristics along with management treatments. This study compared N2O emissions from a fertilizer-based, conventionally managed farm and an organically managed farm that uses legume cover crops as a primary nutrient source. The objective of the study was to assess how management regimes and slope positions interact to impact N2O emissions and soil characteristics. The field experiment was conducted in two adjacent grain farms in upstate New York that both have been under consistent management for 20 years. In the organic farm, red clover was frost-seeded into a winter grain (spelt), and then incorporated in the spring as a nutrient source for the subsequent corn plants. In contrast, the conventionally managed farm used inorganic fertilizer as the nutrient source. Gas measurement was conducted at two landscape positions at both farms: 1) shoulder and 2) toeslope positions. Comparable N2O emissions were found in the clover-corn phase in the organic site and the bare fallow-corn phase in the conventional site. The spelt-corn phase in the organic farm had the lowest N2O emissions. Soil nitrate concentration was the best predictor for seasonal average N2O emissions. The impact of landscape position on N2O emissions was only found in the conventional site, which was driven by higher denitrfication at toeslopes. In the organic farm, such effect was confounded by higher clover biomass at shoulder slopes. Our study shows that the impact of landscape characteristics on N2O emissions could differ across sites based on the complex interplay between environmental conditions and management.

  20. Unexpected nondenitrifier nitrous oxide reductase gene diversity and abundance in soils

    PubMed Central

    Sanford, Robert A.; Wagner, Darlene D.; Wu, Qingzhong; Chee-Sanford, Joanne C.; Thomas, Sara H.; Cruz-García, Claribel; Rodríguez, Gina; Massol-Deyá, Arturo; Krishnani, Kishore K.; Ritalahti, Kirsti M.; Nissen, Silke; Konstantinidis, Konstantinos T.; Löffler, Frank E.

    2012-01-01

    Agricultural and industrial practices more than doubled the intrinsic rate of terrestrial N fixation over the past century with drastic consequences, including increased atmospheric nitrous oxide (N2