WorldWideScience

Sample records for n2o emissioon looduslikest

  1. N2O and NOy

    Science.gov (United States)

    Kawa, S. R.; Jackman, C. H.; Douglass, A. R.; Strahan, S. E.

    2003-01-01

    The principal loss processes for ozone in the stratosphere are either directly or indirectly closely coupled to the abundance and distribution of reactive oxides of nitrogen (NOy). The main source of NOy in the stratosphere is N2O, a trace gas that is changing significantly as a result of anthropogenic forcing. Thus diagnosis of the distributions of N2O, NOy, and their coupling is required to evaluate any chemistry-climate model aspiring to accurately simulate ozone change. In the NASA Assessment of the Effects of High-speed Aircraft in the Stratosphere: 1998 we found that the sensitivity of various models ozone to perturbation did correspond consistently with their background NOy distribution. Coordinated NOy and N2O mixing ratio distributions are available from observations: ER-2 aircraft in the lower stratosphere and ATMOS and balloon profiles to higher altitudes at a subset of latitudes and seasons. Although close comparison to these diagnostics is crucial, unfortunately the distributions are due to a combination of transport and chemical processes, and isolating the source of differences is not always simple. However, in combination with other transport and photochemical diagnostics, comparison with N2O and NOy can be very instructive in evaluation of model processes and performance.

  2. N2O formation in combustion systems

    International Nuclear Information System (INIS)

    1989-11-01

    The objective of this project is to characterize N 2 O emissions from combustion sources emphasizing N 2 O emissions from post-combustion selective gas phase NO x reduction processes and reburning. The processes to be evaluated include ammonia, urea and cyanuric acid injection and reburning. The project includes pilot-scale testing at two facilities supported by chemical kinetic modeling. Testing will be performed on both a gas-fired plug flow combustor and a pulverized-coal fired combustor. Work performed to date has included the performance of the initial detailed chemical kinetics calculations. These calculations showed that both urea and cyanuric acid produce significant quantities of N 2 O, while NH 3 injection produced negligible amounts. These kinetics data support limited test results reported for cyanuric acid and ammonia injection. Laboratory work to evaluate the selective gas phase NO x reduction processes listed above will begin in the gas-fired facility early in CY 1990. Testing to evaluate reburning at the coal-fired facility is currently planned to be performed in parallel with the testing at the gas-fired facility. Following completion of that work, additional kinetics calculations will be performed

  3. QCL N2O data final MayAugust2016

    Data.gov (United States)

    U.S. Environmental Protection Agency — The dataset consists of daily measurements of N2O, N2O isotopic abundance and site preference, and CO2 flux. Data are presented as a daily averages of 10 second...

  4. Miniaturized Airborne Instrument for N2O, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Nitrous Oxide (N2O) is an important greenhouse gas, as well as a tracer for stratospheric air mass. We propose to design a miniaturized N2O detector based on direct...

  5. New combination bands of N2O-CO2, N2O-OCS, and N2O-N2 complexes in the N2O ν1 region

    International Nuclear Information System (INIS)

    Rezaei, M.; Moazzen-Ahmadi, N.; Michaelian, K. H.

    2014-01-01

    Spectra of the weakly bound complexes N 2 O-CO 2 , N 2 O-OCS, and N 2 O-N 2 were studied in the region of the ν 1 fundamental of N 2 O (∼2224 cm −1 ) using a tunable quantum cascade laser to probe a pulsed supersonic jet expansion with an effective rotational temperature of about 2.5 K. One new combination band was observed for each complex: a band involving an intermolecular in-plane bending mode for N 2 O-N 2 , a band involving the disrotation (in-plane geared bend) for of N 2 O-CO 2 , and a band involving the out-of-plane torsional vibration for isomer b of N 2 O-OCS. Small perturbations were noted for the N 2 O-OCS band. Because of the absence of theoretical prediction, the nature of the intermolecular bending mode for N 2 O-N 2 has not been identified. The resulting intermolecular frequencies are 34.175(1), 17.107(1), and 22.334(1) cm −1 for N 2 O-CO 2 , N 2 O-OCS, and N 2 O-N 2 , respectively. In addition, the previously known fundamental band of N 2 O-N 2 at 2225.99 cm −1 was analyzed in improved detail. This band exhibits very weak a-type transitions which were not detected in the first infrared observation of this complex, indicating that N 2 O-N 2 is not exactly T-shaped. That is, the N 2 O molecular axis is not exactly perpendicular to the a-inertial axis, in agreement with a previous structural determination of this complex by rotational spectroscopy

  6. New combination bands of N2O-CO2, N2O-OCS, and N2O-N2 complexes in the N2O ν1 region

    Science.gov (United States)

    Rezaei, M.; Michaelian, K. H.; Moazzen-Ahmadi, N.

    2014-01-01

    Spectra of the weakly bound complexes N2O-CO2, N2O-OCS, and N2O-N2 were studied in the region of the ν1 fundamental of N2O (˜2224 cm-1) using a tunable quantum cascade laser to probe a pulsed supersonic jet expansion with an effective rotational temperature of about 2.5 K. One new combination band was observed for each complex: a band involving an intermolecular in-plane bending mode for N2O-N2, a band involving the disrotation (in-plane geared bend) for of N2O-CO2, and a band involving the out-of-plane torsional vibration for isomer b of N2O-OCS. Small perturbations were noted for the N2O-OCS band. Because of the absence of theoretical prediction, the nature of the intermolecular bending mode for N2O-N2 has not been identified. The resulting intermolecular frequencies are 34.175(1), 17.107(1), and 22.334(1) cm-1 for N2O-CO2, N2O-OCS, and N2O-N2, respectively. In addition, the previously known fundamental band of N2O-N2 at 2225.99 cm-1 was analyzed in improved detail. This band exhibits very weak a-type transitions which were not detected in the first infrared observation of this complex, indicating that N2O-N2 is not exactly T-shaped. That is, the N2O molecular axis is not exactly perpendicular to the a-inertial axis, in agreement with a previous structural determination of this complex by rotational spectroscopy.

  7. Greenhouse gas (N2O emission from Portuguese estuaries

    Directory of Open Access Journals (Sweden)

    Célia Gonçalves

    2014-07-01

    Tagus, Minho and Lima estuaries are source of N2O to the atmosphere. Particularly, in Lima estuary anthropogenic N input seems to play an important role on N2O emission. However, in a global perspective N2O attained emissions represent a reduced fraction (2O yr-1, Barnes and Upstill-Goddard, 2011. Values are comparable with those registered in some Portuguese estuaries and other European less eutrophic estuaries. However, it is known that higher N2O emissions in estuaries may occur during winter and spring (Sun et al., 2014. Thus, these systems may represent on an annual basis a larger source of N2O, which can only be clarified in future studies. Only a full comprehension of the global estuarine nitrogen cycle will provide an efficient basis of scientific knowledge for sustainably management of such ecosystems and ultimately reduce N2O emissions.

  8. Quantifying Regional Variations in the Oceanic N2O Source

    Science.gov (United States)

    Suntharalingam, P.; Buitenhuis, E.; Le Quere, C.

    2012-12-01

    The spatial distribution of the oceanic flux of N2O to the atmosphere displays significant variability, influenced by the heterogeneity of in situ marine nitrogen cycling processes. N2O formation in the well-oxygenated open ocean is primarily ascribed to nitrification, while the N2O source from sub-oxic ocean zones results from high-yield formation pathways such as denitrification, enhanced nitrification and complex coupling of these mechanisms. This heterogeneity poses challenges to quantification of the global oceanic N2O source, and to the development of biogeochemical models that can reliably estimate anthropogenic and climate-driven impacts on the marine N2O cycle. Here, we report recent results employing the global ocean biogeochemistry model, NEMO-PlankTOM, to quantify the present-day oceanic flux of N2O, and to characterise the regions of highest uncertainty. We evaluate both empirically-based, and process-based formulations for marine N2O cycling, and focus on quantifying the relative proportions of the oceanic flux from the oxygenated open ocean and from low-oxygen zones. We discuss the major uncertainties in these model-based estimates of the oceanic N2O flux, and assess the implications for reliable estimation of the impacts of anthropogenically-induced perturbations on the marine N2O cycle.

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

    Science.gov (United States)

    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.

  10. N2O production, a widespread trait in fungi

    Science.gov (United States)

    Maeda, Koki; Spor, Aymé; Edel-Hermann, Véronique; Heraud, Cécile; Breuil, Marie-Christine; Bizouard, Florian; Toyoda, Sakae; Yoshida, Naohiro; Steinberg, Christian; Philippot, Laurent

    2015-04-01

    N2O is a powerful greenhouse gas contributing both to global warming and ozone depletion. While fungi have been identified as a putative source of N2O, little is known about their production of this greenhouse gas. Here we investigated the N2O-producing ability of a collection of 207 fungal isolates. Seventy strains producing N2O in pure culture were identified. They were mostly species from the order Hypocreales order--particularly Fusarium oxysporum and Trichoderma spp.--and to a lesser extent species from the orders Eurotiales, Sordariales, and Chaetosphaeriales. The N2O 15N site preference (SP) values of the fungal strains ranged from 15.8‰ to 36.7‰, and we observed a significant taxa effect, with Penicillium strains displaying lower SP values than the other fungal genera. Inoculation of 15 N2O-producing strains into pre-sterilized arable, forest and grassland soils confirmed the ability of the strains to produce N2O in soil with a significant strain-by-soil effect. The copper-containing nitrite reductase gene (nirK) was amplified from 45 N2O-producing strains, and its genetic variability showed a strong congruence with the ITS phylogeny, indicating vertical inheritance of this trait. Taken together, this comprehensive set of findings should enhance our knowledge of fungi as a source of N2O in the environment.

  11. Estimating N2O processes during grassland renewal and grassland conversion to maize cropping using N2O isotopocules

    Science.gov (United States)

    Buchen, Caroline; Well, Reinhard; Flessa, Heinz; Fuß, Roland; Helfrich, Mirjam; Lewicka-Szczebak, Dominika

    2017-04-01

    Grassland break-up due to grassland renewal and grassland conversion to cropland can lead to a flush of mineral nitrogen from decomposition of the old grass sward and the decomposition of soil organic matter. Moreover, increased carbon and nitrogen mineralisation can result in enhanced nitrous oxide (N2O) emissions. As N2O is known to be an important greenhouse gas and a major precursor for ozone depletion, its emissions need to be mitigated by adjusting agricultural management practices. Therefore, it is necessary to understand the N2O processes involved, as well as the contribution of N2O reduction to N2. Apart from the widely used 15N gas flux method, natural abundance isotopic analysis of the four most abundant isotopocules of N2O species is a promising alternative to assess N2O production pathways. We used stable isotope analyses of soil-emitted N2O (δ18ON2O, δ15NN2Obulk and δ15NN2OSP= intramolecular distribution of 15N within the linear N2O molecule) with an isotopocule mapping approach to simultaneously estimate the magnitude of N2O reduction to N2 and the fraction of N2O originating from the bacterial denitrification pathway or fungal denitrification and/or nitrification. This approach is based on endmember areas of isotopic values for the N2O produced from different sources reported in the literature. For this purpose, we calculated two main scenarios with different assumptions for N2O produced: N2O is reduced to N2 before residual N2O is mixed with N2O of various sources (Scenario a) and vice versa (Scenario b). Based on this, we applied seven different scenario variations, where we evaluated the range of possible values for the potential N2O production pathways (heterotrophic bacterial denitrification and/or nitrifier denitrification and fungal denitrification and/or nitrification). This was done by using a range of isotopic endmember values and assuming different fractionation factors of N2O reduction in order to find the most reliable scenario

  12. Nitrous Oxide (N2O) Emissions from Vehicles

    International Nuclear Information System (INIS)

    Becker, K.H.; Kurtenbach, R.; Lorzer, J.C.; Wiesen, P.; Jensen, T.; Wallington, T.J.

    2000-01-01

    N2O is an important greenhouse gas and accurate emission data are required to assess its impact on global climate. It is well established that automobiles, particularly those equipped with 3-way catalysts, emit N2O. However, the vehicle contribution to the global N2O budget is uncertain. We report results of N2O emission measurements performed in a road tunnel in Germany and using a chassis dynamometer system in the USA. We estimate that the global vehicle fleet emits (0.12±0.06) Tg yr-1 of N2O. From the emission factor (g N2O/g CO2) determined an annual N2O emission of (0.12±0.06) Tg yr-1 of N2O (0.08±0.04 Tg N yr-1) for the global vehicle fleet has been estimated which represents 1-4% of the atmospheric growth rate of this species. 9 refs

  13. Soil invertebrate fauna affect N2O emissions from soil

    NARCIS (Netherlands)

    Kuiper, I.; Deyn, de G.B.; Thakur, M.P.; Groenigen, van J.W.

    2013-01-01

    Nitrous oxide (N2O) emissions from soils contribute significantly to global warming. Mitigation of N2O emissions is severely hampered by a lack of understanding of its main controls. Fluxes can only partly be predicted from soil abiotic factors and microbial analyses – a possible role for soil fauna

  14. Modeling global N2O emissions from aquatic systems

    NARCIS (Netherlands)

    Ivens, W.P.M.F.; Tysmans, D.J.J.; Kroeze, C.; Löhr, A.J.; Wijnen, van J.

    2011-01-01

    Human activities on land have increased the N inputs to rivers and coastal waters worldwide. This increased aquatic emissions of nitrous oxide (N2O). Global, spatially explicit modeling of N flows from land to sea and associated N2O emissions have been developed for a number of decades. During the

  15. Production of N2O in grass-clover pastures

    International Nuclear Information System (INIS)

    Carter, M.S.

    2005-09-01

    Agricultural soils are known to be a considerable source of the strong greenhouse gas nitrous oxide (N 2 O), and in soil N 2 O is mainly produced by nitrifying and denitrifying bacteria. In Denmark, grass-clover pastures are an important component of the cropping system in organic as well as conventional dairy farming, and on a European scale grass-clover mixtures represent a large part of the grazed grasslands. Biological dinitrogen (N 2 ) fixation in clover provides a major N input to these systems, but knowledge is sparse regarding the amount of fixed N 2 lost from the grasslands as N2O. Furthermore, urine patches deposited by grazing cattle are known to be hot-spots of N 2 O emission, but the mechanisms involved in the N 2 O production in urine-affected soil are very complex and not well understood. The aim of this Ph.D. project was to increase the knowledge of the biological and physical-chemical mechanisms, which control the production of N2O in grazed grass-clover pastures. Three experimental studies were conducted with the objectives of: 1: assessing the contribution of recently fixed N 2 as a source of N 2 O. 2: examining the link between N 2 O emission and carbon mineralization in urine patches. 3: investigating the effect of urine on the rates and N 2 O loss ratios of nitrification and denitrification, and evaluating the impact of the chemical conditions that arise in urine affected soil. The results revealed that only 3.2 ± 0.5 ppm of the recently fixed N 2 was emitted as N2O on a daily basis. Thus, recently fixed N released via easily degradable clover residues appears to be a minor source of N2O. Furthermore, increased N 2 O emission following urine application at rates up to 5.5 g N m -2 was not caused by enhanced denitrification stimulated by labile compounds released from scorched plant roots. Finally, the increase of soil pH and ammonium following urine application led to raised nitrification rate, which appeared to be the most important factor

  16. N2O Emission from energy crop fields

    International Nuclear Information System (INIS)

    Joergensen, B.J.; Nyholm Joergensen, R.

    1996-03-01

    The interest in N 2 O emissions from soils with energy crops is a results of its properties as a greenhouse gas, since the global warming potential of N 2 O per unit mass is about 320 times greater than CO 2 . The contribution of N 2 O from the soil to the atmosphere may increase due to agricultural management. Consequently, large N 2 O emissions can lower the reduction of the greenhouse effect achieved by the substitution of fossil fuels by energy crops. For this reason it is crucial to find the crops for combustion with the lowest potential for emission of N 2 O from the soil per produced energy unit. The aims of this study were to assess the annual N 2 O flux from a Miscanthus 'Giganteus' (M. 'Giganteus') and winter rye (Secale cereale) field, and to investigate the factors affecting the N 2 O emission. To obtain these aims a method was developed for measurements in tall crops. The thesis contains a literature review on the N 2 O emission from the soils, a section with development of the technique for N 2 O flux measurements, and an experimental section. Finally, the thesis contains a section where the results are discussed in relation to the use of energy crops. In all the filed studies, the N 2 O emission was measured by using a new developed closed-chamber technique. The main advantages of the chamber method were the ability to contain growing plants up to a height of 3 m, and the relatively large area (2X2m) covered by each other. Soils with annual and perennial crops can be expected to emit less then 3 kg N 2 O ha -1 yr -1 . This amount corresponds to 960 kg CO 2 ha -1 yr -1 compared to a total CO 2 reduction of 10 to 19 tons CO 2 ha -1 yr -1 using the energy crops as substitution for fossil fuels. An efficient way to reduce the N 2 O emission is to exclude use of fertiliser but this also reduces the dry matter yield and consequently also the CO 2 reduction per unit dry matter. Following the guidelines for good agricultural practice concerning the

  17. Isotopic Monitoring of N2O Emissions from Wastewater Treatment: Evidence for N2O Production Associated with Anammox Metabolism?

    Science.gov (United States)

    Harris, E. J.; Wunderlin, P.; Joss, A.; Emmenegger, L.; Kipf, M.; Wolf, B.; Mohn, J.

    2015-12-01

    Microbial production is the major source of N2O, the strongest greenhouse gas produced within the nitrogen cycle, and the most important stratospheric ozone destructant released in the 21st century. Wastewater treatment is an important and growing source of N2O, with best estimates predicting N2O emissions from this sector will have increased by >25% by 2020. Novel treatment employing partial nitritation-anammox, rather than traditional nitrification-denitrification, has the potential to achieve a neutral carbon footprint due to increased biogas production - if N2O production accounts for treatment can be applied to our understanding of N cycling in the natural environment. This study presents the first online isotopic measurements of offgas N2O from a partial-nitritation anammox reactor 1. The measured N2O isotopic composition - in particular the N2O isotopic site preference (SP = δ15Nα - δ15Nβ) - was used to understand N2O production pathways in the reactor. When N2O emissions peaked due to high dissolved oxygen concentrations, low SP showed that N2O was produced primarily via nitrifier denitrification by ammonia oxidizing bacteria (AOBs). N2O production by AOBs via NH2OH oxidation, in contrast, did not appear to be important under any conditions. Over the majority of the one-month measurement period, the measured SP was much higher than expected following our current understanding of N2O production pathways 2. SP reached 41‰ during normal operating conditions and achieved a maximum of 45‰ when nitrite was added under anoxic conditions. These results could be explained by unexpectedly strong heterotrophic N2O reduction despite low dissolved organic matter concentrations, or by an incomplete understanding of isotopic fractionation during N2O production from NH2OH oxidation by AOBs - however the explanation most consistent with all results is a previously unknown N2O production pathway associated with anammox metabolism. Harris et al. (2015) Water Res., 83

  18. UV-induced N2O emission from plants

    Science.gov (United States)

    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.

  19. Decomposition of N2O in the nitric acid industry

    International Nuclear Information System (INIS)

    Van den Brink, R.W.; Pieterse, J.A.Z.; Melian-Cabrera, I.; Mul, G.; Kapteijn, F.; Moulijn, J.A.

    2005-03-01

    The nitric acid industry is one of the major sources of the greenhouse gas N2O, which is 310 times more effective than CO2 in trapping heat in the atmosphere. One of the most promising techniques is direct decomposition of N2O in the tail gases of nitric acid plants. The state-of-the-art catalysts are only active at temperatures above 400C, which means that they can be used only in a limited number of plants. The aim of this research is to develop a catalyst that lowers the temperature for N2O decomposition to below 350C. This will increase the number of plants that can use the direct decomposition technique for N2O removal and will improve the cost efficiency for plants with a higher temperature. Many researchers have investigated iron-zeolites in recent years. They are active for N2O decomposition, show a high stability in the tail gases of nitric acid plants and are promoted by the presence of NOx in the tail gases (2,3). Noble metal catalysts for N2O decomposition have been studied less thoroughly than iron zeolites. They show high N2O decomposition activity in in diluted N2O streams, but are inhibited by the oxygen, water and NOx present in nitric acid plant tail gases (4). This paper defines relationships between the structure of iron-zeolite and noble metal catalysts and their activity for N2O decomposition. Several parameters of preparation and post-modification were evaluated for their importance in the formation of active species. Based on the knowledge of the structure activity relations, novel catalysts were found with a higher activity for N2O decomposition than the state-of-the-art catalysts

  20. Oceanic N2O emissions in the 21st century

    Science.gov (United States)

    Martinez-Rey, J.; Bopp, L.; Gehlen, M.; Tagliabue, A.; Gruber, N.

    2014-12-01

    The ocean is a substantial source of nitrous oxide (N2O) to the atmosphere, but little is known on how this flux might change in the future. Here, we investigate the potential evolution of marine N2O emissions in the 21st century in response to anthropogenic climate change using the global ocean biogeochemical model NEMO-PISCES. We implemented two different parameterizations of N2O production, which differ primarily at low oxygen (O2) conditions. When forced with output from a climate model simulation run under the business-as-usual high CO2 concentration scenario (RCP8.5), our simulations suggest a decrease of 4 to 12% in N2O emissions from 2005 to 2100, i.e., a reduction from 4.03/3.71 to 3.54/3.56 Tg N yr-1 depending on the parameterization. The emissions decrease strongly in the western basins of the Pacific and Atlantic oceans, while they tend to increase above the Oxygen Minimum Zones (OMZs), i.e., in the Eastern Tropical Pacific and in the northern Indian Ocean. The reduction in N2O emissions is caused on the one hand by weakened nitrification as a consequence of reduced primary and export production, and on the other hand by stronger vertical stratification, which reduces the transport of N2O from the ocean interior to the ocean surface. The higher emissions over the OMZ are linked to an expansion of these zones under global warming, which leads to increased N2O production associated primarily with denitrification. From the perspective of a global climate system, the averaged feedback strength associated with the projected decrease in oceanic N2O emissions amounts to around -0.009 W m-2 K-1, which is comparable to the potential increase from terrestrial N2O sources. However, the assesment for a compensation between the terrestrial and marine feedbacks calls for an improved representation of N2O production terms in fully coupled next generation of Earth System Models.

  1. UV-induced N2O emission from plants

    DEFF Research Database (Denmark)

    Bruhn, Dan; Albert, Kristian Rost; Mikkelsen, Teis Nørgaard

    2014-01-01

    tests were conducted with a range of species to study the controls and possible loci of UV-induced N 2 O emission from plants. Plants released N 2 O in response to natural sunlight at rates of c. 20 e 50 nmol m 2 h 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 N 2 O 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 N 2 O formation ap- pears to be at the very surface of leaves. However, only c. 26% of the UV-induced N 2 O appears to originate from plant-N. Further, the process is dependent on atmospheric oxygen concentration. Our work dem- onstrates that ecosystem emission of the important...

  2. Slowdown of N2O emissions from China's croplands

    Science.gov (United States)

    Zhou, F.; Shang, Z.; Ciais, P.; Piao, S.; Tian, H.; Saikawa, E.; Zaehle, S.; Del Grosso, S. J.; Galloway, J. N.

    2016-12-01

    To feed the increasing population, China has experienced a rapid agricultural development over past decades, accompanied by increased fertilizer consumptions in croplands, but the magnitude, trend, and causes of the associated nitrous oxide (N2O) emissions has remain unclear. The primary sources of this uncertainty are conflicting estimates of fertilizer consumption and emission factors, the latter being uncertain because of very few regional representativeness of the Nrate-flux relationships in China. Here we re-estimate China's N2O emissions from croplands using three different methods: flux upscaling technique, process-based models and atmospheric inversion, and also analyze the corresponding drivers using an attribution approach. The three methods produce similar estimates of N2O emissions in the range of 0.67 ± 0.08 to 0.62± 0.11 Tg nitrogen per year, which is 29% larger than the estimates by the Emission Database for Global Atmospheric Research (EDGAR) that is adopted by Intergovernmental Panel on Climate Change (IPCC) as the emission baseline and twofold larger than the latest Chinese national report submitted to the United Nations Framework Convention on Climate Change, but the revised trend slows down after 2005. Fertilizer N application per area is the dominant factor driving the increase in N2O emissions across most cropping regions from 1990 to 2004, but climate-induced change of emission factors has also controlled N2O flux from 2005 onwards. Our findings suggest that, as precipitation would increase in North China but decline in the South in future, EF will increasingly control China's agri. soil emissions of N2O, unless offset by larger reductions of fertilizer consumptions.

  3. Market Analysis DeN2O. Market potential for reduction of N2O emissions at nitric acid facilities

    International Nuclear Information System (INIS)

    Smit, A.W.; Gent, M.M.C.; Van den Brink, R.W.

    2001-05-01

    ECN has developed a technique for the removal of nitrous oxide (N2O) from the tail gases of a nitric acid plant. The aim of this project was to make an assessment of the market opportunities of this technique. To this end a study was made of the relevant international regulations and agreements on the field of climate policy. The formulation of an international greenhouse gas policy and concomitant flexible mechanisms is a prerequisite for the market introduction of any N2O abatement technique. The available techniques and techniques in development for N2O abatement in the nitric acid industry are described and the strengths and weaknesses are given. Furthermore, the costs per ton CO2 equivalents removed are estimated. Direct decomposition of N2O (either in the NH3 combustion reactor or downstream the absorber) are the most cost efficient techniques. Finally, the number and sizes of nitric acid plants in Europe and the developments in the fertiliser market are described. The current difficult fertiliser market makes the nitric acid producers reluctant to invest in N2O abatement technologies

  4. Quantitative CARS spectroscopy of CO2 and N2O.

    Science.gov (United States)

    Hall, R J; Stufflebeam, J H

    1984-12-01

    Experimental and theoretical investigations of the CARS spectroscopy of CO2(2v2) and N2O(v3) were carried out. The experimental spectra were measured in a heated test cell, and excellent agreement with the observed temperature dependences was obtained from numerical simulations. Assignments were made for all hot bands, and the role of collisional narrowing was quantified. Observed nonresonant susceptibility effects in pure N2O have made it possible to estimate the nonresonant background susceptibility for this molecule by using the resonant contribution as a reference calibration.

  5. N 2 O Emissions and Inorganic N Release Following Incorporation ...

    African Journals Online (AJOL)

    West African Journal of Applied Ecology ... The results from the study demonstrated that whilst there is the potential for N2O emission to be controlled through varying ratios of residue:fertiliser input, the magnitude and direction of interactions between these N sources vary between different species as a result of their ...

  6. Measurements of N2O emissions at the landscape scale

    DEFF Research Database (Denmark)

    Schelde, Kirsten; Cellier, P.; Bertolini, T.

    2011-01-01

    Nitrous oxide emissions from agricultural land are variable at the landscape scale due to variability in land use, management, soil type, and topography. A field experiment was carried out in a typical mixed farming landscape near Bjerringbro, Denmark, to investigate the main sources of variation...... the importance of the climatic regime on N2O fluxes....

  7. TransCom N2O model inter-comparison - Part 2 : Atmospheric inversion estimates of N2O emissions

    NARCIS (Netherlands)

    Thompson, R. L.; Ishijima, K.; Saikawa, E.; Corazza, M.; Karstens, U.; Patra, P. K.; Bergamaschi, P.; Chevallier, F.; Dlugokencky, E.; Prinn, R. G.; Weiss, R. F.; O'Doherty, S.; Fraser, P. J.; Steele, L. P.; Krummel, P. B.; Vermeulen, A.; Tohjima, Y.; Jordan, A.; Haszpra, L.; Steinbacher, M.; Van Der Laan, S.; Aalto, T.; Meinhardt, F.; Popa, Maria Elena|info:eu-repo/dai/nl/375806407; Moncrieff, J.; Bousquet, P.

    2014-01-01

    This study examines N2O emission estimates from five different atmospheric inversion frameworks based on chemistry transport models (CTMs). The five frameworks differ in the choice of CTM, meteorological data, prior uncertainties and inversion method but use the same prior emissions and observation

  8. TransCom N2O model inter-comparison, Part II : Atmospheric inversion estimates of N2O emissions

    NARCIS (Netherlands)

    Thompson, R. L.; Ishijima, K.; Saikawa, E.; Corazza, M.; Karstens, U.; Patra, P. K.; Bergamaschi, P.; Chevallier, F.; Dlugokencky, E.; Prinn, R. G.; Weiss, R. F.; O'Doherty, S.; Fraser, P. J.; Steele, L. P.; Krummel, P. B.; Vermeulen, A.; Tohjima, Y.; Jordan, A.; Haszpra, L.; Steinbacher, M.; Van Der Laan, S.; Aalto, T.; Meinhardt, F.; Popa, Maria Elena; Moncrieff, J.; Bousquet, P.

    2014-01-01

    This study examines N2O emission estimates from 5 different atmospheric inversion frameworks. The 5 frameworks differ in the choice of atmospheric transport model, meteorological data, prior uncertainties and inversion method but use the same prior emissions and observation dataset. The mean

  9. Global and regional emissions estimates for N2O

    Science.gov (United States)

    Saikawa, E.; Prinn, R. G.; Dlugokencky, E.; Ishijima, K.; Dutton, G. S.; Hall, B. D.; Langenfelds, R.; Tohjima, Y.; Machida, T.; Manizza, M.; Rigby, M.; O'Doherty, S.; Patra, P. K.; Harth, C. M.; Weiss, R. F.; Krummel, P. B.; van der Schoot, M.; Fraser, P. J.; Steele, L. P.; Aoki, S.; Nakazawa, T.; Elkins, J. W.

    2014-05-01

    We present a comprehensive estimate of nitrous oxide (N2O) emissions using observations and models from 1995 to 2008. High-frequency records of tropospheric N2O are available from measurements at Cape Grim, Tasmania; Cape Matatula, American Samoa; Ragged Point, Barbados; Mace Head, Ireland; and at Trinidad Head, California using the Advanced Global Atmospheric Gases Experiment (AGAGE) instrumentation and calibrations. The Global Monitoring Division of the National Oceanic and Atmospheric Administration/Earth System Research Laboratory (NOAA/ESRL) has also collected discrete air samples in flasks and in situ measurements from remote sites across the globe and analyzed them for a suite of species including N2O. In addition to these major networks, we include in situ and aircraft measurements from the National Institute of Environmental Studies (NIES) and flask measurements from the Tohoku University and Commonwealth Scientific and Industrial Research Organization (CSIRO) networks. All measurements show increasing atmospheric mole fractions of N2O, with a varying growth rate of 0.1-0.7% per year, resulting in a 7.4% increase in the background atmospheric mole fraction between 1979 and 2011. Using existing emission inventories as well as bottom-up process modeling results, we first create globally gridded a priori N2O emissions over the 37 years since 1975. We then use the three-dimensional chemical transport model, Model for Ozone and Related Chemical Tracers version 4 (MOZART v4), and a Bayesian inverse method to estimate global as well as regional annual emissions for five source sectors from 13 regions in the world. This is the first time that all of these measurements from multiple networks have been combined to determine emissions. Our inversion indicates that global and regional N2O emissions have an increasing trend between 1995 and 2008. Despite large uncertainties, a significant increase is seen from the Asian agricultural sector in recent years, most likely

  10. Global terrestrial N2O budget for present and future

    Science.gov (United States)

    Olin, Stefan; Xing, Xu-Ri; Wårlind, David; Eliasson, Peter; Smith, Ben; Arneth, Almut

    2017-04-01

    Nitrogen (N) plays an important role in plant productivity and physiology and is the main limiting nutrient in a majority of the terrestrial ecosystems. The enhanced input of anthropogenic reactive nitrogen (Nr) in agriculture have enhanced global food production, but with adverse effects on biodiversity and water quality, and substantially increased emissions of N trace gases that affect air quality and climate. Emissions of N gases affects the climate, either through cloud forming nitrogen oxides (NOx) gases or as greenhouse gases, where nitrous oxide (N2O) is the most important being approximately 300 times more potent than carbon dioxide (CO2). In this study we use the process-based global vegetation model Lund-Potsdam-Jena General Ecosystem Simulator (LPJ-GUESS) (Olin et al. 2015) that recently have incorporated a new soil N transformation scheme, adopted from Xu-Ri and Prentice (2008), which makes it possible to study the N2O emission respond to changes in climate and CO2 concentration as well as anthropogenic N enhancements on a global scale. We present here results from the validation of the new model against site-scale N2O measurements from agricultural and non-agricultural ecosystems. We will also present results from a study to examine how land use, land use change and anthropogenic N fertilisation influence historical and future global N2O emissions. This new development represents a key component within future projects in CMIP6 (LUMIP) and in EC-Earth for the EU Horizon 2020 project CRESCENDO. Olin, S., Lindeskog, M., Pugh, T., Schurgers, G., Mischurow, M., Wårlind, D., Zaehle, S., Stocker, B., Smith, B. and Arneth, A. 2015. Soil carbon management in large-scale Earth system modelling: implications for crop yields and nitrogen leaching. Earth System Dynamics, 6, 745-768. Xu-Ri and Prentice IC. 2008. Terrestrial nitrogen cycle simulation with a dynamic global vegetation model. Global Change Biology, 14, 1745-1764.

  11. Metal exchanged zeolites for catalytic decomposition of N2O

    Czech Academy of Sciences Publication Activity Database

    Lebhsetwar, N.; Dhakad, M.; Biniwale, R.; Mitsuhasi, T.; Haneda, H.; Reddy, P.S.S.; Bakardjieva, Snejana; Šubrt, Jan; Kumar, S.; Kumar, V.; Saiprasad, P.; Rayalu, S.

    2009-01-01

    Roč. 141, 1-2 (2009), s. 205-210 ISSN 0920-5861. [18th National Symposium and Indo-US seminar on Catalysis. Dehradun, 16.04.2007-18.04.2007] Grant - others:CSIR(IN) SIP-16 (1,3) Institutional research plan: CEZ:AV0Z40320502 Keywords : N2O decomposition * catalyst * zeolite Subject RIV: CA - Inorganic Chemistry Impact factor: 3.526, year: 2009

  12. Characterization of Water Coordination to Ferrous Nitrosyl Complexes with fac-N2O, cis-N2O2, and N2O3 Donor Ligands.

    Science.gov (United States)

    McCracken, John; Cappillino, Patrick J; McNally, Joshua S; Krzyaniak, Matthew D; Howart, Michael; Tarves, Paul C; Caradonna, John P

    2015-07-06

    Electron paramagnetic resonance (EPR) experiments were done on a series of S = (3)/2 ferrous nitrosyl model complexes prepared with chelating ligands that mimic the 2-His-1-carboxylate facial triad iron binding motif of the mononuclear nonheme iron oxidases. These complexes formed a comparative family, {FeNO}(7)(N2Ox)(H2O)3-x with x = 1-3, where the labile coordination sites for the binding of NO and solvent water were fac for x = 1 and cis for x = 2. The continuous-wave EPR spectra of these three complexes were typical of high-spin S = (3)/2 transition-metal ions with resonances near g = 4 and 2. Orientation-selective hyperfine sublevel correlation (HYSCORE) spectra revealed cross peaks arising from the protons of coordinated water in a clean spectral window from g = 3.0 to 2.3. These cross peaks were absent for the {FeNO}(7)(N2O3) complex. HYSCORE spectra were analyzed using a straightforward model for defining the spin Hamiltonian parameters of bound water and showed that, for the {FeNO}(7)(N2O2)(H2O) complex, a single water conformer with an isotropic hyperfine coupling, Aiso = 0.0 ± 0.3 MHz, and a dipolar coupling of T = 4.8 ± 0.2 MHz could account for the data. For the {FeNO}(7)(N2O)(H2O)2 complex, the HYSCORE cross peaks assigned to coordinated water showed more frequency dispersion and were analyzed with discrete orientations and hyperfine couplings for the two water molecules that accounted for the observed orientation-selective contour shapes. The use of three-pulse electron spin echo envelope modulation (ESEEM) data to quantify the number of water ligands coordinated to the {FeNO}(7) centers was explored. For this aspect of the study, HYSCORE spectra were important for defining a spectral window where empirical integration of ESEEM spectra would be the most accurate.

  13. Continuous measurements of N2O emissions from arable fields

    Science.gov (United States)

    Wallman, Magdalena; Lammirato, Carlo; Rütting, Tobias; Delin, Sofia; Weslien, Per; Klemedtsson, Leif

    2017-04-01

    Agriculture represents 59 % of the anthropogenic nitrous oxide (N2O) emissions, according to the IPCC (Ciais et al. 2013). N2O emissions are typically irregular and vary widely in time and space, which makes it difficult to get a good representation of the emissions (Henault et al. 2012), particularly if measurements have low frequency and/or cover only a short time period. Manual measurements are, for practical reasons, often short-term and low-frequent, or restricted to periods where emissions are expected to be high, e.g. after fertilizing. However, the nature of N2O emissions, being largely unpredictable, calls for continuous or near-continuous measurements over long time periods. So far, rather few long-term, high resolution measurements of N2O emissions from arable fields are reported; among them are Flessa et al. (2002) and Senapati et al. (2016). In this study, we have a two-year data set (2015-2017) with hourly measurements from ten automatic chambers, covering unfertilized controls as well as different nitrogen fertilizer treatments. Grain was produced on the field, and effects of tillage, harvest and other cropping measures were covered. What we can see from the experiment is that (a) the unfertilized control plots seem to follow the same emission pattern as the fertilized plots, at a level similar to the standard mineral fertilized plots (120 kg N ha-1 yr-1) and (b) freeze/thaw emissions are comparable in size to emissions after fertilizing. These two findings imply that the importance of fertilizing to the overall N2O emissions from arable soils may be smaller than previously expected. References: Ciais, P., C. Sabine, G. Bala, L. Bopp, V. Brovkin, J. Canadell et al. 2013: Carbon and Other Biogeochemical Cycles. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung et

  14. Effects of flooding-induced N2O production, consumption and emission dynamics on the annual N2O emission budget in wetland soil

    DEFF Research Database (Denmark)

    Jørgensen, Christian Juncher; Elberling, Bo

    2012-01-01

    during mid-summer when the WL was at its seasonally lowest counterbalancing ~6.4% of the total annual net N2O emission budget. Main surface emission periods of N2O were observed when the water level and associated peaks in subsurface N2O concentrations were gradually decreasing to soil depths down to 40...... production and consumption capacities where >500 nmol N2O cm-3 were sequentially produced and consumed in less than 24 hrs. It is concluded that a higher future frequency of flooding induced N2O emissions will have a very limited effect on the net annual N2O emission budget as long as NO3- availability...

  15. Validation of ACE-FTS N2O measurements

    Directory of Open Access Journals (Sweden)

    G. P. Stiller

    2008-08-01

    Full Text Available The Atmospheric Chemistry Experiment (ACE, also known as SCISAT, was launched on 12 August 2003, carrying two instruments that measure vertical profiles of atmospheric constituents using the solar occultation technique. One of these instruments, the ACE Fourier Transform Spectrometer (ACE-FTS, is measuring volume mixing ratio (VMR profiles of nitrous oxide (N2O from the upper troposphere to the lower mesosphere at a vertical resolution of about 3–4 km. In this study, the quality of the ACE-FTS version 2.2 N2O data is assessed through comparisons with coincident measurements made by other satellite, balloon-borne, aircraft, and ground-based instruments. These consist of vertical profile comparisons with the SMR, MLS, and MIPAS satellite instruments, multiple aircraft flights of ASUR, and single balloon flights of SPIRALE and FIRS-2, and partial column comparisons with a network of ground-based Fourier Transform InfraRed spectrometers (FTIRs. Between 6 and 30 km, the mean absolute differences for the satellite comparisons lie between −42 ppbv and +17 ppbv, with most within ±20 ppbv. This corresponds to relative deviations from the mean that are within ±15%, except for comparisons with MIPAS near 30 km, for which they are as large as 22.5%. Between 18 and 30 km, the mean absolute differences for the satellite comparisons are generally within ±10 ppbv. From 30 to 60 km, the mean absolute differences are within ±4 ppbv, and are mostly between −2 and +1 ppbv. Given the small N2O VMR in this region, the relative deviations from the mean are therefore large at these altitudes, with most suggesting a negative bias in the ACE-FTS data between 30 and 50 km. In the comparisons with the FTIRs, the mean relative differences between the ACE-FTS and FTIR partial columns (which cover a mean altitude range of 14 to 27 km are within ±5.6% for eleven of the twelve contributing stations. This mean relative difference is negative at ten stations

  16. Extreme emission of N2O from tropical wetland soil (Pantanal, South America)

    DEFF Research Database (Denmark)

    Møller, Lars Liengård Holten; Nielsen, Lars Peter; Revsbech, Niels Peter

    2013-01-01

    Nitrous oxide (N(2)O) is an important greenhouse gas and ozone depleter, but the global budget of N(2)O remains unbalanced. Currently, ~25% of the global N(2)O emission is ascribed to uncultivated tropical soils, but the exact locations and controlling mechanisms are not clear. Here we present...... these wetland soils is generally representative to the Pantanal, we suggest that this undisturbed tropical wetland potentially contributes ~1.7% to the global N(2)O emission budget, a significant single source of N(2)O....... the first study of soil N(2)O emission from the Pantanal indicating that this South American wetland may be a significant natural source of N(2)O. At three sites, we repeatedly measured in situ fluxes of N(2)O and sampled porewater nitrate [Formula: see text] during the low water season in 2008 and 2009...

  17. Upland Trees Contribute to Exchange of Nitrous Oxide (N2O) in Forest Ecosystems

    Science.gov (United States)

    Tian, H.; Thompson, R.; Canadell, J.; Winiwarter, W.; Machacova, K.; Maier, M.; Halmeenmäki, E.; Svobodova, K.; Lang, F.; Pihlatie, M.; Urban, O.

    2017-12-01

    The increase in atmospheric nitrous oxide (N2O) concentration contributes to the acceleration of the greenhouse effect. However, the role of trees in the N2O exchange of forest ecosystems is still an open question. While the soils of temperate and boreal forests were shown to be a natural source of N2O, trees have been so far overlooked in the forest N2O inventories. We determined N2O fluxes in common tree species of boreal and temperate forests: Scots pine (Pinus sylvestris), Norway spruce (Picea abies), downy and silver birch (Betula pubescens, B. pendula), and European beech (Fagus sylvatica). We investigated (1) whether these tree species exchange N2O with the atmosphere under natural field conditions, (2) how the tree N2O fluxes contribute to the forest N2O balance, and (3) whether these fluxes show seasonal dynamics. The studies were performed in a boreal forest (SMEAR II station, Finland; June 2014 - May 2015) and two temperate mountain forests (White Carpathians, Czech Republic; Black Forest, Germany; June and July 2015). Fluxes of N2O in mature tree stems and forest floor were measured using static chamber systems followed by chromatographic and photo-acoustic analyses of N2O concentration changes. Pine, spruce and birch trees were identified as net annual N2O sources. Spruce was found the strongest emitter (0.27 mg ha-1 h-1) amounting thus up to 2.5% of forest floor N2O emissions. All tree species showed a substantial seasonality in stem N2O flux that was related to their physiological activity and climatic variables. In contrast, stems of beech trees growing at soils consuming N2O may act as a substantial sink of N2O from the atmosphere. Consistent N2O consumption by tree stems ranging between -12.1 and -35.2 mg ha-1 h-1 and contributing by up to 3.4% to the forest floor N2O uptake is a novel finding in contrast to current studies presenting trees as N2O emitters. To understand these fluxes, N2O exchange of photoautotrophic organisms associated with

  18. Observation of Combination Bands Involving Intermolecular Vibrations of N_2O-N_2, N_2O-OCS and N_2O-CO_2 Complexes Using AN External Cavity Quantum Cascade Laser

    Science.gov (United States)

    Rezaei, M.; Sheybani-Deloui, S.; Moazzen-Ahmadi, N.; McKellar, A. R. W.

    2013-06-01

    Spectra of the weakly-bound N_2O-CO_2, N_2O-OCS, and N_2O-N_2 complexes in the region of the N_2O ν_1 fundamental band (˜2224 cm^{-1}) are observed in a pulsed supersonic slit jet expansion probed with a quantum cascade laser. One new band is observed for each complex: two combination bands involving the intermolecular in-plane bending for N_2O-CO_2 and N_2O-N_2 complexes, and the out-of-plane torsional vibration for N_2O-OCS. The resulting intermolecular frequencies are 34.17, 17.11 and 22.33 cm^{-1} for N_2O-CO_2, N_2O-OCS, and N_2O-N_2 complexes, respectively. The intermolecular vibrations provide clear spectroscopic data against which theory can be benchmarked. These results will be discussed, along with a brief introduction to our pulsed-jet supersonic apparatus which has been retrofitted by an infrared cw external-cavity quantum cascade laser (QCL) manufactured by Daylight Solutions. The QCL is used in the rapid-scan signal averaging mode. Although the repetition rate of the QCL is limited by its PZT scan rate, which is 100 Hz, we describe a simple technique to increase the effective repetition rate to 625 Hz. In addition, we have significantly reduced the long term frequency drift of the QCL by locking the laser frequency to the sides of a reference line. Limin Zheng, Soo-Ying Lee, Yunpeng Lu, and Minghui Yang, J. Chem. Phys. 138, 044302 (2013).

  19. Nitrous Oxide (N2O) emissions from human waste in 1970-2050

    NARCIS (Netherlands)

    Strokal, M.; Kroeze, C.

    2014-01-01

    Nitrous oxide (N2O) is an important contributor to climate change. Human waste is an important source of N2O emissions in several world regions, and its share in global emissions may increase in the future. In this paper we, therefore, address N2O emission from human waste: collected (from treatment

  20. Towards an agronomic assessment of N2O emissions: a case study for arable crops

    NARCIS (Netherlands)

    Groenigen, van J.W.; Velthof, G.L.; Oenema, O.; Groenigen, van K.J.; Kessel, van C.

    2010-01-01

    Agricultural soils are the main anthropogenic source of nitrous oxide (N2O), largely because of nitrogen (N) fertilizer use. Commonly, N2O emissions are expressed as a function of N application rate. This suggests that smaller fertilizer applications always lead to smaller N2O emissions. Here we

  1. Decomposition and reduction of N2O over Limestone under FBC Conditions

    DEFF Research Database (Denmark)

    Johnsson, Jan Erik; Jensen, Anker; Vaaben, Rikke

    1997-01-01

    The addition of limestone for sulfur retention in FBC has in many cases been observed to influence the emission of N2O. The catalytic activity of N2O over calcined Stevns Chalk for decomposition of N2O in a laboratory fixed bed quartz reactor was measured. It was found that calcined Stevns Chalk ...

  2. Investigation of the N2O emission strength in the U. S. Corn Belt

    Science.gov (United States)

    Fu, Congsheng; Lee, Xuhui; Griffis, Timothy J.; Dlugokencky, Edward J.; Andrews, Arlyn E.

    2017-09-01

    Nitrous oxide (N2O) has a high global warming potential and depletes stratospheric ozone. The U. S. Corn Belt plays an important role in the global anthropogenic N2O budget. To date, studies on local surface N2O emissions and the atmospheric N2O budget have commonly used Lagrangian models. In the present study, we used an Eulerian model - Weather Research and Forecasting Chemistry (WRF-Chem) model to investigate the relationships between N2O emissions in the Corn Belt and observed atmospheric N2O mixing ratios. We derived a simple equation to relate the emission strengths to atmospheric N2O mixing ratios, and used the derived equation and hourly atmospheric N2O measurements at the KCMP tall tower in Minnesota to constrain agricultural N2O emissions. The modeled spatial patterns of atmospheric N2O were evaluated against discrete observations at multiple tall towers in the NOAA flask network. After optimization of the surface flux, the model reproduced reasonably well the hourly N2O mixing ratios monitored at the KCMP tower. Agricultural N2O emissions in the EDGAR42 database needed to be scaled up by 19.0 to 28.1 fold to represent the true emissions in the Corn Belt for June 1-20, 2010 - a peak emission period. Optimized mean N2O emissions were 3.00-4.38, 1.52-2.08, 0.61-0.81 and 0.56-0.75 nmol m- 2 s- 1 for June 1-20, August 1-20, October 1-20 and December 1-20, 2010, respectively. The simulated spatial patterns of atmospheric N2O mixing ratios after optimization were in good agreement with the NOAA discrete observations during the strong emission peak in June. Such spatial patterns suggest that the underestimate of emissions using IPCC (Inter-governmental Panel on Climate Change) inventory methodology is not dependent on tower measurement location.

  3. Nonpolar nitrous oxide dimer: Observation of combination bands of (14N2O)2 and (15N2O)2 involving the torsion and antigeared bending modes

    Science.gov (United States)

    Rezaei, M.; Michaelian, K. H.; Moazzen-Ahmadi, N.

    2012-03-01

    Spectra of the nonpolar nitrous oxide dimer in the region of the N2O ν1 fundamental band were observed in a supersonic slit-jet apparatus. The expansion gas was probed using radiation from a quantum cascade or a tunable diode laser, with both lasers employed in a rapid-scan signal averaging mode. Four bands were observed and analyzed: new combination bands involving the intermolecular conrotation of the monomers (Ag antigeared bend) for (14N2O)2 and (15N2O)2, the previously reported torsional combination band for (14N2O)2 with improved signal-to-noise ratio, and the same torsional combination band for (15N2O)2. The resulting frequencies for the intermolecular antigeared mode are 96.0926(1) and 95.4912(1) cm-1 for (14N2O)2 and (15N2O)2, respectively. This is the third of the four intermolecular frequencies which has now been measured experimentally, the others being the out-of-plane torsion and the geared bend modes. Our experimental results are in good agreement with two recent high level ab initio theoretical calculations.

  4. High Resolution Measurements of Nitrous Oxide (N2O in the Elbe Estuary

    Directory of Open Access Journals (Sweden)

    Lisa Brase

    2017-05-01

    Full Text Available Nitrous oxide (N2O is one of the most important greenhouse gases and a major sink for stratospheric ozone. Estuaries are sites of intense biological production and N2O emissions. We aimed to identify hot spots of N2O production and potential pathways contributing to N2O concentrations in the surface water of the tidal Elbe estuary. During two research cruises in April and June 2015, surface water N2O concentrations were measured along the salinity gradient of the Elbe estuary by using a laser-based on-line analyzer coupled to an equilibrator. Based on these high-resolution N2O profiles, N2O saturations, and fluxes across the surface water/atmosphere interface were calculated. Additional measurements of DIN concentrations, oxygen concentration, and salinity were performed. Highest N2O concentrations were determined in the Hamburg port region reaching maximum values of 32.3 nM in April 2015 and 52.2 nM in June 2015. These results identify the Hamburg port region as a significant hot spot of N2O production, where linear correlations of AOU-N2Oxs indicate nitrification as an important contributor to N2O production in the freshwater part. However, in the region with lowest oxygen saturation, sediment denitrification obviously affected water column N2O saturation. The average N2O saturation over the entire estuary was 201% (SD: ±94%, with an average estuarine N2O flux density of 48 μmol m−2 d−1 and an overall emission of 0.18 Gg N2O y−1. In comparison to previous studies, our data indicate that N2O production pathways over the whole estuarine freshwater part have changed from predominant denitrification in the 1980s toward significant production from nitrification in the present estuary. Despite a significant reduction in N2O saturation compared to the 1980s, N2O concentrations nowadays remain on a high level, comparable to the mid-90s, although a steady decrease of DIN inputs occurred over the last decades. Hence, the Elbe estuary still

  5. Mechanisms of nitrous oxide (N2O) formation and reduction in denitrifying biofilms.

    Science.gov (United States)

    Sabba, Fabrizio; Picioreanu, Cristian; Nerenberg, Robert

    2017-12-01

    Nitrous oxide (N 2 O) is a potent greenhouse gas that can be formed in wastewater treatment processes by ammonium oxidizing and denitrifying microorganisms. While N 2 O emissions from suspended growth systems have been extensively studied, and some recent studies have addressed emissions from nitrifying biofilms, much less is known about N 2 O emissions from denitrifying biofilm processes. This research used modeling to evaluate the mechanisms of N 2 O formation and reduction in denitrifying biofilms. The kinetic model included formation and consumption of key denitrification species, including nitrate (NO3-), nitrite (NO2-), nitric oxide (NO), and N 2 O. The model showed that, in presence of excess of electron donor, denitrifying biofilms have two distinct layers of activity: an outer layer where there is net production of N 2 O and an inner layer where there is net consumption. The presence of oxygen (O 2 ) had an important effect on N 2 O emission from suspended growth systems, but a smaller effect on biofilm systems. The effects of NO3- and O 2 differed significantly based on the biofilm thickness. Overall, the effects of biofilm thickness and bulk substrate concentrations on N 2 O emissions are complex and not always intuitive. A key mechanism for denitrifying biofilms is the diffusion of N 2 O and other intermediates from one zone of the biofilm to another. This leads to zones of N 2 O formation or consumption transformations that would not exist in suspended growth systems. © 2017 Wiley Periodicals, Inc.

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

    Science.gov (United States)

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

    2017-12-01

    Nitrogen fertilisation of agricultural soil contributes significantly to emissions of the potent greenhouse gas nitrous oxide (N 2 O), which is generated during denitrification and, in oxic soils, mainly by ammonia oxidisers. Although laboratory cultures of ammonia oxidising bacteria (AOB) and archaea (AOA) produce N 2 O, their relative activities in soil are unknown. This work tested the hypothesis that AOB dominate ammonia oxidation and N 2 O production under conditions of high inorganic ammonia (NH 3 ) input, but result mainly from the activity of AOA when NH 3 is derived from mineralisation. 1-octyne, a recently discovered inhibitor of AOB, was used to distinguish N 2 O production resulting from archaeal and bacterial ammonia oxidation in soil microcosms, and specifically inhibited AOB growth, activity and N 2 O production. In unamended soils, ammonia oxidation and N 2 O production were lower and resulted mainly from ammonia oxidation by AOA. The AOA N 2 O yield relative to nitrite produced was half that of AOB, likely due to additional enzymatic mechanisms in the latter, but ammonia oxidation and N 2 O production were directly linked in all treatments. Relative contributions of AOA and AOB to N 2 O production, therefore, reflect their respective contributions to ammonia oxidation. These results suggest potential mitigation strategies for N 2 O emissions from fertilised agricultural soils. © 2016 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

  7. The effects of nitrogen fertilization on N2O emissions from a rubber plantation.

    Science.gov (United States)

    Zhou, Wen-Jun; Ji, Hong-Li; Zhu, Jing; Zhang, Yi-Ping; Sha, Li-Qing; Liu, Yun-Tong; Zhang, Xiang; Zhao, Wei; Dong, Yu-Xin; Bai, Xiao-Long; Lin, You-Xin; Zhang, Jun-Hui; Zheng, Xun-Hua

    2016-06-21

    To gain the effects of N fertilizer applications on N2O emissions and local climate change in fertilized rubber (Hevea brasiliensis) plantations in the tropics, we measured N2O fluxes from fertilized (75 kg N ha(-1) yr(-1)) and unfertilized rubber plantations at Xishuangbanna in southwest China over a 2-year period. The N2O emissions from the fertilized and unfertilized plots were 4.0 and 2.5 kg N ha(-1) yr(-1), respectively, and the N2O emission factor was 1.96%. Soil moisture, soil temperature, and the area weighted mean ammoniacal nitrogen (NH4(+)-N) content controlled the variations in N2O flux from the fertilized and unfertilized rubber plantations. NH4(+)-N did not influence temporal changes in N2O emissions from the trench, slope, or terrace plots, but controlled spatial variations in N2O emissions among the treatments. On a unit area basis, the 100-year carbon dioxide equivalence of the fertilized rubber plantation N2O offsets 5.8% and 31.5% of carbon sink of the rubber plantation and local tropical rainforest, respectively. When entire land area in Xishuangbanna is considered, N2O emissions from fertilized rubber plantations offset 17.1% of the tropical rainforest's carbon sink. The results show that if tropical rainforests are converted to fertilized rubber plantations, regional N2O emissions may enhance local climate warming.

  8. Aircraft Observations of Nitrous Oxide (N2O) in the San Joaquin Valley of California

    Science.gov (United States)

    Muto, S.; Herrera, S.; Pusede, S.

    2017-12-01

    Agriculture is the largest source of anthropogenic nitrous oxide (N2O) in the U.S. While it is generally known which processes produce N2O, there is considerable uncertainty in controls over N2O emissions. Factors that determine N2O fluxes, such as soil properties and manure management, are highly variable in space and time, and, as a result, it has proven difficult to upscale chamber-derived soil flux measurements to regional spatial scales. Aircraft observations provide a regional picture of the N2O spatial distribution, but, because N2O is very long-lived, it is challenging to attribute measured concentrations of N2O to distinct local sources, especially over areas with complex and integrated land use. This study takes advantage of a novel aircraft N2O dataset collected onboard the low-flying, slow-moving NASA C-23 Sherpa in the San Joaquin Valley (SJV) of California, a region with a variety of N2O sources, including dairies, feedlots, fertilized cropland, and industrial facilities. With these measurements, we link observed N2O enhancements to specific sources at sub-inventory spatial scales. We compare our results with area-weighted emission profiles obtained by integrating detailed emission inventory data, agricultural statistics, and GIS source mapping.

  9. Constraints on global oceanic emissions of N2O from observations and models

    Directory of Open Access Journals (Sweden)

    E. T. Buitenhuis

    2018-04-01

    Full Text Available We estimate the global ocean N2O flux to the atmosphere and its confidence interval using a statistical method based on model perturbation simulations and their fit to a database of ΔpN2O (n =  6136. We evaluate two submodels of N2O production. The first submodel splits N2O production into oxic and hypoxic pathways following previous publications. The second submodel explicitly represents the redox transformations of N that lead to N2O production (nitrification and hypoxic denitrification and N2O consumption (suboxic denitrification, and is presented here for the first time. We perturb both submodels by modifying the key parameters of the N2O cycling pathways (nitrification rates; NH4+ uptake; N2O yields under oxic, hypoxic and suboxic conditions and determine a set of optimal model parameters by minimisation of a cost function against four databases of N cycle observations. Our estimate of the global oceanic N2O flux resulting from this cost function minimisation derived from observed and model ΔpN2O concentrations is 2.4 ± 0.8 and 2.5 ± 0.8 Tg N yr−1 for the two N2O submodels. These estimates suggest that the currently available observational data of surface ΔpN2O constrain the global N2O flux to a narrower range relative to the large range of results presented in the latest IPCC report.

  10. N2O Emissions From a Fertilized Grassland: Modeling and Measurements

    Science.gov (United States)

    Hsieh, C.

    2005-12-01

    N2O emissions from a fertilized grassland near Cork, Ireland were continuously measured during 2003 using the eddy covariance method. For most of the year N2O emissions were close to zero and the bulk of the emission occurred in only eight major events, each event lasting from two to twenty days. This data set was used to test the N2O emissions predicted by the DNDC (DeNitrification-DeComposition) model. Good agreement between measured and modeled N2O emissions was found, thus providing a basis for using the model to simulate (a) background N2O emissions and (b) the effect of future climate perturbations on N2O emissions. Our future climate projections are based on the standard Hadley Center model output of the IS92a scenario for Ireland in which the average temperature increases for the whole year and precipitation increases in winter but decreases in summer. The measured annual N2O emission was 11.6 kg N/ha. A total of 335 kg/ha of chemical and organic N was applied, giving an emission factor of 3.4%, uncorrected for background emission. Based on the DNDC model prediction with zero N applications, the background emission accounts for 15% of the total annual observed N2O emission. The DNDC model predicts that the future climate shifts based on the IS92a scenario will increase total annual N2O emission by 45% (7.0 kg N2O-N/ha). By comparison, a decrease of 10% in total N applications (in order to comply with EU water quality legislation) leads to a predicted reduction in current N2O emissions of only 7% (0.9 kg N2O-N/ha). Thus the projected increase in N2O emission caused by climate perturbations is far larger than the decrease expected from reduced fertilization to comply with water quality legislation.

  11. Investigation of N2O Production from 266 and 532 nm Laser Flash Photolysis of O3/N2/O2 Mixtures

    Science.gov (United States)

    Estupinan, E. G.; Nicovich, J. M.; Li, J.; Cunnold, D. M.; Wine, P. H.

    2002-01-01

    Tunable diode laser absorption spectroscopy has been employed to measure the amount of N2O produced from laser flash photolysis of O3/N2/O2 mixtures at 266 and 532 nm. In the 532 nm photolysis experiments very little N2O is observed, thus allowing an upper limit yield of 7 x 10(exp -8) to be established for the process O3 + N2 yield N2O + O2, where O3 is nascent O3 that is newly formed via O(3P(sub J)) + O2 recombination (with vibrational excitation near the dissociation energy of O3). The measured upper limit yield is a factor of approx. 600 smaller than a previous literature value and is approximately a factor of 10 below the threshold for atmospheric importance. In the 266 nm photolysis experiments, significant N2O production is observed and the N2O quantum yield is found to increase linearly with pressure over the range 100 - 900 Torr in air bath gas. The source of N2O in the 266 nm photolysis experiments is believed to be the addition reaction O(1D(sub 2)) + N2 + M yields (k(sub sigma)) N2O + M, although reaction of (very short-lived) electronically excited O3 with N2 cannot be ruled out by the available data. Assuming that all observed N2O comes from the O(1D(sub 2)) + N2 + M reaction, the following expression describes the temperature dependence of k(sub sigma) (in its third-order low-pressure limit) that is consistent with the N2O yield data: k(sub sigma) = (2.8 +/- 0.1) x 10(exp -36)(T/300)(sup -(0-88+0.36)) cm(sup 6) molecule(sup -2)/s, where the uncertainties are 2(sigma) and represent precision only. The accuracy of the reported rate coefficients at the 95% confidence level is estimated to be 30 - 40% depending on the temperature. Model calculations suggest that gas phase processes initiated by ozone absorption of a UV photon represent about 1.4% of the currently estimated global source strength of atmospheric N2O. However, these processes could account for a significant fraction of the oxygen mass-independent enrichment observed in atmospheric N2O, and

  12. Elucidating source processes of N2O fluxes following grassland-to-field-conversion using isotopologue signatures of soil-emitted N2O

    Science.gov (United States)

    Roth, G.; Giesemann, A.; Well, R.; Flessa, H.

    2012-04-01

    Conversion of grassland to arable land often causes enhanced nitrous oxide (N2O) emissions to the atmosphere. This is due to the tillage of the sward and subsequent decomposition of organic matter. Prediction of such effects is uncertain so far because emissions may differ depending on site and soil conditions. The processes of N2O turnover (nitrification, production by bacterial or fungal denitrifiers, bacterial reduction to N2) are difficult to identify, however. Isotopologue signatures of N2O such as δ18O, average δ15N (δ15Nbulk) and 15N site preference (SP = difference in δ15N between the central and peripheral N positions of the asymmetric N2O molecule) can be used to characterize N2O turnover processes using the known ranges of isotope effects of the various N2O pathways. We aim to evaluate the impact of grassland-to-field-conversion on N2O fluxes and the governing processes using isotopic signatures of emitted N2O. At two sites, in Kleve (North Rhine-Westphalia, Germany, conventional farming) and Trenthorst (Schleswig-Holstein, Germany, organic farming), a four times replicated plot experiment with (i) mechanical conversion (ploughing, maize), (ii) chemical conversion (broadband herbicide, maize per direct seed) and (iii) continuous grassland as reference was started in April 2010. In Trenthorst we additionally established a (iv) field with continuous maize cultivation as further reference. Over a period of two years, mineral nitrogen (Nmin) content was measured weekly on soil samples taken from 0-10 cm and 10-30 cm depth. Soil water content and N2O emissions were measured weekly as well. Gas samples were collected using a closed chamber system. Isotope ratio mass spectrometry was carried out on gas samples from selected high flux events to determine δ18O, δ15Nbulk and SP of N2O. δ18O and SP of N2O exhibited a relatively large range (32 to 72 ‰ and 6 to 34 ‰, respectively) indicating highly variable process dynamics. The data-set is grouped

  13. N2O emission from plant surfaces – light stimulated and a global phenomenon

    DEFF Research Database (Denmark)

    Mikkelsen, Teis Nørgaard; Bruhn, Dan; Ambus, Per

    2017-01-01

    Nitrous oxide (N2O) is an important long-lived greenhouse gas and precursor of stratospheric ozone depletingmono-nitrogen oxides. The atmospheric concentration of N2O is persistently increasing; however, large uncertaintiesare associated with the distinct source strengths. Here we investigate...... for the first time N2O emission fromterrestrial vegetation in response to natural solar ultra violet radiation. We conducted field site measurementsto investigate N2O atmosphere exchange from grass vegetation exposed to solar irradiance with and withoutUV-screening. Further laboratory tests were conducted...... with a range of species to study the controls and possibleloci of UV-induced N2O emission from plants. Plants released N2O in response to natural sunlight at rates of c.20-50 nmol m-2 h-1, mostly due to the UV component. The emission rate is temperature dependent with a ratherhigh activation energy indicative...

  14. Effects of N2O narcosis on the contraction and repayment of an oxygen debt

    Science.gov (United States)

    Schatte, C. L.; Hall, P.; Fitch, J. W.; Loader, J. E.

    1974-01-01

    The oxygen deficit, oxygen debt, and the difference between them were measured in five male and three female subjects during and after exercise while breathing either air or a normoxic mixture containing 33% N2O and nitrogen. With the exception of a higher respiratory quotient at rest in N2O, there were no statistically significant differences for oxygen consumption, carbon dioxide production, expired gas volume, heart rate or blood lactate while breathing N2O during rest, exercise, or recovery. An appreciably, but not statistically, greater mean oxygen deficit was found in N2O along with a significantly greater mean oxygen debt; deficit-debt difference was unaffected by N2O. It was speculated that N2O narcosis did not affect the ability to utilize oxygen but that the response to the greater oxygen need of exercise may have been slowed with perhaps a concomitant greater depletion of stored high energy compounds.

  15. The heterogeneous catalytic reduction of NO and N2O mixture by carbon monoxide

    International Nuclear Information System (INIS)

    Gassan-zedeh, G.Z.; Seyidbayova, S.F.

    2003-01-01

    Kinetics of the simultaneous reduction N 2 O and NO by CO on CuCo 2 O 4 has been studied. The reactants are adsorbed onto the coordination-unsaturated cations of the catalyst. The studies showed that the reactions of N 2 O and CO and of NO and CO occur between the adsorbed reactants on the catalyst surface; the catalyst surface is partially reduced during both these reactions. It was found that NO inhibits the reaction between N 2 O and CO, because N 2 O and NO compete for the active surface sites. The adsorption capacity of the catalyst is significantly higher for NO than for N 2 O and hence NO displaces N 2 Oads from the surface. The inhibition occurs on strongly localized sites and does not affect on the behaviour of the remaining free sites. At such blockage, the N 2 O reduction rate decreases in direct proportion to the amount of adsorbed NO

  16. Effect of plastic mulching and nitrapyrin on N2O concentration and emissions in China under climate change

    Science.gov (United States)

    Zhao, C.; Zhu, C.

    2017-12-01

    Fertilized agricultural soils are the main source of atmospheric nitrous oxide (N2O). In this study, both soil N2O concentration in the profile and N2O emission were measured to quantify the effect of plastic mulching and nitrapyrin on N2O dynamic in an oasis cotton field. During the observation period, both N2O concentration and N2O emissions rapidly increased following fertigation, and soil temperature, moisture and mineral N content were the main factors influencing N2O. Temporal variation in N2O emission coincided with changes in N2O content in all soil layers, indicating that the accumulation of N2O likely drives the release of N2O into the atmosphere. The crop yields, N2O content (the sum of aqueous and gaseous phases) in the soil and N2O emissions increased linearly as the application of N fertilizer increased from 80 to 400 kg N ha-1. Plastic mulching increased the crop yields by 16-21%, increased the N2O contents by 88-99%, and reduced the cumulative N2O emissions by 19-28%, indicating that the application of plastic film reduced N2O emission probably through restricted the N2O diffusion process, and limited the N2O production through enhanced the N uptake of cotton. The addition of nitrapyrin to the N fertilizer significantly reduced the levels of N2O without influencing crop yield, with N2O content in the soil profile and cumulative N2O emissions decreasing by 25-32% and 23-42%, respectively. Overall, our result suggested the combined use of plastic film and nitrapyrin could be an efficient practice to reduce N2O emission in the oasis cotton field. Keywords: N2O emissions; plastic film mulching; nitrapyrin; climate change

  17. Effect of watershed urbanization on N2O emissions from the Chongqing metropolitan river network, China

    Science.gov (United States)

    He, Yixin; Wang, Xiaofeng; Chen, Huai; Yuan, Xingzhong; Wu, Ning; Zhang, Yuewei; Yue, Junsheng; Zhang, Qiaoyong; Diao, Yuanbin; Zhou, Lilei

    2017-12-01

    Watershed urbanization, an integrated anthropogenic perturbation, is another considerable global concern in addition to that of global warming and may significantly enrich the N loadings of watersheds, which then greatly influences the nitrous oxide (N2O) production and fluxes of these aquatic systems. However, little is known about the N2O dynamics in human-dominated metropolitan river networks. In this study, we present the temporal and spatial variations in N2O saturation and emission in the Chongqing metropolitan river network, which is undergoing intensified urbanization. The N2O saturation and fluxes at 84 sampling sites ranged from 126% to 10536% and from 4.5 to 1566.8 μmol N2O m-2 d-1, with means of 1780% and 261 μmol N2O m-2 d-1. The riverine N2O saturation and fluxes increased along with the urbanization gradient and urbanization rate, with disproportionately higher values in urban rivers due to the N2O-rich sewage inputs and enriched in situ N substrates. We found a clear seasonal pattern of N2O saturation, which was co-regulated by both water temperature and precipitation. Regression analysis indicated that the N substrates and dissolved oxygen (DO) that controlled nitrogen metabolism acted as good predictors of the N2O emissions of urban river networks. Particularly, phosphorus (P) and hydromorphological factors (water velocity, river size and bottom substrate) had stronger relationships with the N2O saturation and could also be used to predict the N2O emission hotspots in regions with rapid urbanization. In addition, the default emission factors (EF5-r) used in the Intergovernmental Panel on Climate Change (IPCC) methodology may need revision given the differences among the physical and chemical factors in different rivers, especially urban rivers.

  18. Multifactor controls on terrestrial N2O flux over North America from 1979 through 2010

    Directory of Open Access Journals (Sweden)

    C. Q. Lu

    2012-04-01

    Full Text Available Nitrous oxide (N2O is a potent greenhouse gas which also contributes to the depletion of stratospheric ozone (O3. However, the magnitude and underlying mechanisms for the spatiotemporal variations in the terrestrial sources of N2O are still far from certain. Using a process-based ecosystem model (DLEM – the Dynamic Land Ecosystem Model driven by multiple global change factors, including climate variability, nitrogen (N deposition, rising atmospheric carbon dioxide (CO2, tropospheric O3 pollution, N fertilizer application, and land conversion, this study examined the spatial and temporal variations in terrestrial N2O flux over North America and further attributed these variations to various driving factors. From 1979 to 2010, the North America cumulatively emitted 53.9 ± 0.9 Tg N2O-N (1 Tg = 1012 g, of which global change factors contributed 2.4 ± 0.9 Tg N2O-N, and baseline emission contributed 51.5 ± 0.6 Tg N2O-N. Climate variability, N deposition, O3 pollution, N fertilizer application, and land conversion increased N2O emission while the elevated atmospheric CO2 posed opposite effect at continental level; the interactive effect among multiple factors enhanced N2O emission over the past 32 yr. N input, including N fertilizer application in cropland and N deposition, and multi-factor interaction dominated the increases in N2O emission at continental level. At country level, N fertilizer application and multi-factor interaction made large contribution to N2O emission increase in the United States of America (USA. The climate variability dominated the increase in N2O emission from Canada. N inputs and multiple factors interaction made large contribution to the increases in N2O emission from Mexico. Central and southeastern parts of the North America – including central Canada, central USA, southeastern USA, and all of Mexico – experienced increases in N2O emission from 1979 to 2010. The fact that climate variability and multi

  19. Hotspots of soil N2O emission enhanced through water absorption by plant residue

    Energy Technology Data Exchange (ETDEWEB)

    Kravchenko, A.N.; Toosi, E.R.; Guber, A.K.; Ostrom, N.E.; Yu, J.; Azeem, K.; Rivers, M.L.; Robertson , G.P. (UAF Pakistan); (UC); (Hubei); (MSU)

    2017-06-05

    N2O is a highly potent greenhouse gas and arable soils represent its major anthropogenic source. Field-scale assessments and predictions of soil N2O emission remain uncertain and imprecise due to the episodic and microscale nature of microbial N2O production, most of which occurs within very small discrete soil volumes. Such hotspots of N2O production are often associated with decomposing plant residue. Here we quantify physical and hydrological soil characteristics that lead to strikingly accelerated N2O emissions in plant residue-induced hotspots. Results reveal a mechanism for microscale N2O emissions: water absorption by plant residue that creates unique micro-environmental conditions, markedly different from those of the bulk soil. Moisture levels within plant residue exceeded those of bulk soil by 4–10-fold and led to accelerated N2O production via microbial denitrification. The presence of large (Ø >35 μm) pores was a prerequisite for maximized hotspot N2O production and for subsequent diffusion to the atmosphere. Understanding and modelling hotspot microscale physical and hydrologic characteristics is a promising route to predict N2O emissions and thus to develop effective mitigation strategies and estimate global fluxes in a changing environment.

  20. Extreme emission of n(2)o from tropical wetland soil (pantanal, South america).

    Science.gov (United States)

    Liengaard, Lars; Nielsen, Lars Peter; Revsbech, Niels Peter; Priemé, Anders; Elberling, Bo; Enrich-Prast, Alex; Kühl, Michael

    2012-01-01

    Nitrous oxide (N(2)O) is an important greenhouse gas and ozone depleter, but the global budget of N(2)O remains unbalanced. Currently, ∼25% of the global N(2)O emission is ascribed to uncultivated tropical soils, but the exact locations and controlling mechanisms are not clear. Here we present the first study of soil N(2)O emission from the Pantanal indicating that this South American wetland may be a significant natural source of N(2)O. At three sites, we repeatedly measured in situ fluxes of N(2)O and sampled porewater nitrate [Formula: see text] during the low water season in 2008 and 2009. In 2010, 10 sites were screened for in situ fluxes of N(2)O and soil [Formula: see text] content. The in situ fluxes of N(2)O were comparable to fluxes from heavily fertilized forests or agricultural soils. An important parameter affecting N(2)O emission rate was precipitation, inducing peak emissions of >3 mmol N(2)O m(-2) day(-1), while the mean daily flux was 0.43 ± 0.03 mmol N(2)O m(-2) day(-1). Over 170 days of the drained period, we estimated non-wetted drained soil to contribute 70.0 mmol N(2)O m(-2), while rain-induced peak events contributed 9.2 mmol N(2)O m(-2), resulting in a total N(2)O emission of 79.2 mmol N(2)O m(-2). At the sites of repeated sampling, the pool of porewater nitrate varied [Formula: see text] with higher concentrations of [Formula: see text] (p < 0.05) found in drained soil than in water-logged soil, indicating dynamic shifts between nitrification and denitrification. In the field, O(2) penetrated the upper 60 cm of drained soil, but was depleted in response to precipitation. Upon experimental wetting the soil showed rapid O(2) depletion followed by N(2)O accumulation and a peak emission of N(2)O [Formula: see text] Assuming that the observed emission of N(2)O from these wetland soils is generally representative to the Pantanal, we suggest that this undisturbed tropical wetland potentially

  1. Biological N2O fixation in the Eastern South Pacific Ocean and marine cyanobacterial cultures.

    Directory of Open Access Journals (Sweden)

    Laura Farías

    Full Text Available Despite the importance of nitrous oxide (N2O in the global radiative balance and atmospheric ozone chemistry, its sources and sinks within the Earth's system are still poorly understood. In the ocean, N2O is produced by microbiological processes such as nitrification and partial denitrification, which account for about a third of global emissions. Conversely, complete denitrification (the dissimilative reduction of N2O to N2 under suboxic/anoxic conditions is the only known pathway accountable for N2O consumption in the ocean. In this work, it is demonstrated that the biological assimilation of N2O could be a significant pathway capable of directly transforming this gas into particulate organic nitrogen (PON. N2O is shown to be biologically fixed within the subtropical and tropical waters of the eastern South Pacific Ocean, under a wide range of oceanographic conditions and at rates ranging from 2 pmol N L(-1 d(- to 14.8 nmol N L(-1 d(-1 (mean ± SE of 0.522 ± 1.06 nmol N L(-1 d(-1, n = 93. Additional assays revealed that cultured cyanobacterial strains of Trichodesmium (H-9 and IMS 101, and Crocosphaera (W-8501 have the capacity to directly fix N2O under laboratory conditions; suggesting that marine photoautotrophic diazotrophs could be using N2O as a substrate. This metabolic capacity however was absent in Synechococcus (RCC 1029. The findings presented here indicate that assimilative N2O fixation takes place under extreme environmental conditions (i.e., light, nutrient, oxygen where both autotrophic (including cyanobacteria and heterotrophic microbes appear to be involved. This process could provide a globally significant sink for atmospheric N2O which in turn affects the oceanic N2O inventory and may also represent a yet unexplored global oceanic source of fixed N.

  2. Distribution of N2O in the Baltic Sea during transition from anoxic to oxic conditions

    Directory of Open Access Journals (Sweden)

    S. Walter

    2006-01-01

    Full Text Available In January 2003, a major inflow of cold and oxygen-rich North Sea Water terminated an ongoing stagnation period in parts of the central Baltic Sea. In order to investigate the role of North Sea Water inflow in the production of nitrous oxide (N2O, we measured dissolved and atmospheric N2O at 26 stations in the southern and central Baltic Sea in October 2003. At the time of our cruise, water renewal had proceeded to the eastern Gotland Basin, whereas the western Gotland Basin was still unaffected by the inflow. The deep water renewal was detectable in the distributions of temperature, salinity, and oxygen concentrations as well as in the distribution of the N2O concentrations: Shallow stations in the Kiel Bight and Pomeranian Bight were well-ventilated with uniform N2O concentrations near equilibrium throughout the water column. In contrast, stations in the deep basins, such as the Bornholm and the Gotland Deep, showed a clear stratification with deep water affected by North Sea Water. Inflowing North Sea Water led to changed environmental conditions, especially enhanced oxygen (O2 or declining hydrogen sulphide (H2S concentrations, thus, affecting the conditions for the production of N2O. Pattern of N2O profiles and correlations with parameters like oxygen and nitrate differed between the basins. Because of the positive correlation between ΔN2O and AOU in oxic waters the dominant production pathway seems to be nitrification rather than denitrification. Advection of N2O by North Sea Water was found to be of minor importance. A rough budget revealed a significant surplus of in situ produced N2O after the inflow. However, due to the permanent halocline, it can be assumed that the N2O produced does not reach the atmosphere. Hydrographic aspects therefore are decisive factors determining the final release of N2O produced to the atmosphere.

  3. Indirect N2O emission due to atmospheric N deposition for the Netherlands

    International Nuclear Information System (INIS)

    Denier van der Gon, H.; Bleeker, A.

    2005-10-01

    Nitrous oxide (N2O) is a potent greenhouse gas produced in soils and aquatic systems. The UNFCCC requires participants to report 'indirect' N2O emissions, following from agricultural N losses to ground- and surface water and N deposition on (other) ecosystems due to agricultural sources. Indirect N2O emission due to atmospheric N deposition is presently not reported by the Netherlands. In this paper, we quantify the consequences of various tiers to estimate indirect N2O due to deposition for a country with a high agricultural N use and discuss the reliability and potential errors in the IPCC methodology. A literature review suggests that the current IPCC default emission factor for indirect N2O from N deposition is underestimated by a factor 2. Moreover, considering anthropogenic N emissions from agriculture only and not from e.g., traffic and industry, results in further underestimation of indirect N2O emissions. We calculated indirect N2O emissions due to Dutch anthropogenic N emissions to air by using official Dutch N emission data as input in an atmospheric transport and deposition model in combination with land use databases. Next, land use-specific emission factors were used to estimate the indirect N2O emission. This revealed that (1) for some countries, like the Netherlands, most agricultural N emitted will be deposited on agricultural soils, not on natural ecosystems and, (2) indirect N2O emissions are at least 20% higher because more specific emission factors can be applied that are higher than the IPCC default. The results suggest that indirect N2O emission due to deposition is underestimated in current N2O budgets

  4. Direct N2O5 reactivity measurements at a polluted coastal site

    Directory of Open Access Journals (Sweden)

    C. J. Gaston

    2012-03-01

    Full Text Available Direct measurements of N2O5 reactivity on ambient aerosol particles were made during September 2009 at the Scripps Institution of Oceanography (SIO Pier facility located in La Jolla, CA. N2O5 reactivity measurements were made using a custom flow reactor and the particle modulation technique alongside measurements of aerosol particle size distributions and non-refractory composition. The pseudo-first order rate coefficients derived from the particle modulation technique and the particle surface area concentrations were used to determine the population average N2O5 reaction probability, γ(N2O5, approximately every 50 min. Insufficient environmental controls within the instrumentation trailer led us to restrict our analysis primarily to nighttime measurements. Within this subset of data, γ(N2O5 ranged from γ(N2O5 are important, such as organic coatings or non-aqueous particles. The largest apparent driver of day-to-day variability in the measured γ(N2O5 at this site was the particle nitrate loading, as inferred from both the measured particle composition and the parameterizations. The relative change in measured γ(N2O5 as a function of particle nitrate loading appears to be consistent with expectations based on laboratory data, providing direct support for the atmospheric importance of the so-called "nitrate effect".

  5. N2O production dynamics in nitrifying/denitrifying activated sludge under defined environmental conditions

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Jensen, Marlene Mark; Petersen, Morten S.

    Nitrous oxide (N2O) is a gaseous pollutant emitted as an unwanted product in wastewater treatment plants during the nitrification-denitrification process. Even though the emission capacity of the process with respect to this compound is still under debate, N2O has been identified as an important ...

  6. Residual sleepiness after N2O sedation: a randomized control trial [ISRCTN88442975

    Directory of Open Access Journals (Sweden)

    Lichtor J Lance

    2004-05-01

    Full Text Available Abstract Background Nitrous oxide (N2O provides sedation for procedures that result in constant low-intensity pain. How long do individuals remain sleepy after receiving N2O? We hypothesized that drug effects would be apparent for an hour or more. Methods This was a randomized, double blind controlled study. On three separate occasions, volunteers (N = 12 received 100% oxygen or 20% or 40% N2O for 30 min. Dependent measures included the multiple sleep latency test (MSLT, a Drug Effects/Liking questionnaire, visual analogue scales, and five psychomotor tests. Repeated measures analysis of variance was performed with drug and time as factors. Results During inhalation, drug effects were apparent based on the questionnaire, visual analogue scales, and psychomotor tests. Three hours after inhaling 100% oxygen or 20% N2O, subjects were sleepier than if they breathed 40% N2O. No other drug effects were apparent 1 hour after inhalation ceased. Patients did not demonstrate increased sleepiness after N2O inhalation. Conclusion We found no evidence for increased sleepiness greater than 1 hour after N2O inhalation. Our study suggests that long-term effects of N2O are not significant.

  7. Measurement of N2O emissions from drip irrigated soils in a pomegranate orchard

    Science.gov (United States)

    Agriculture is a major contributor to greenhouse gas N2O emissions. Developing a sustainable crop production system should consider minimizing N2O emissions and increasing N use efficiency. Pomegranate is a new emerging crop in the San Joaquin Valley of California because of the fruits value in pro...

  8. Nitrous oxide (N2O). Emission inventory and options for control in the Netherlands

    NARCIS (Netherlands)

    Kroeze C; LAE

    1994-01-01

    This study was initiated to overview current knowledge on nitrous oxide (N2O). The report reviews atmospheric behaviour of N2O, global sources and sinks, Dutch emissions in 1990, options to reduce emissions, and past and future emissions. Despite the uncertainties involved, it is likely that without

  9. Decomposition and reduction of N2O over Limestone under FBC Conditions

    DEFF Research Database (Denmark)

    Johnsson, Jan Erik; Jensen, Anker; Vaaben, Rikke

    1997-01-01

    The addition of limestone for sulfur retention in FBC has in many cases been observed to influence the emission of N2O. The catalytic activity of N2O over calcined Stevns Chalk for decomposition of N2O in a laboratory fixed bed quartz reactor was measured. It was found that calcined Stevns Chalk...... is a very active catalyst for N2O decomposition in an inert atmosphere, and the presence of 3 vol% CO increased the rate of N2O destruction by a factor of 5 due to the catalytic reduction of N2O by CO. The activity decreased with increasing CO2 concentration, and uncalcined or recarbonated limestone had...... negligible activity. Sulfation of the calcined limestone under oxidizing conditions lowered the activity, however sulfidation under reducing conditions showed that CaS is an active catalyst for the reduction of N2O by CO. Without CO present a gas solid reaction between N2O and CaS takes place and SO2...

  10. Potential N2O emissions from leguminous tree plantation soils in the humid tropics

    Science.gov (United States)

    Arai, Seiko; Ishizuka, Shigehiro; Ohta, Seiichi; Ansori, Saifuddin; Tokuchi, Naoko; Tanaka, Nagaharu; Hardjono, Arisman

    2008-06-01

    We compared nitrous oxide (N2O) emissions over 1 year from soils of plantations growing acacia, which is a leguminous plant capable of symbiotic nitrogen fixation in root nodules, and secondary forests in Sumatra, Indonesia. N2O emissions from acacia plantation soils fluctuated seasonally, from high in the wetter season to low in the drier season, whereas N2O emissions from secondary forest soils were low throughout the year. Water-filled-pore-space data showed that denitrification contributed substantially to N2O emissions from soils at acacia sites. The average annual N2O flux in acacia plantations was 2.56 kg N ha-1 a-1, which was eight times higher than that from secondary forest soils (0.33 kg N ha-1 a-1). In secondary forests, NH4+ was the dominant form of inorganic nitrogen. However, in acacia plantations, the NH4+: NO3- ratio was relatively lower than that in secondary forests. These results suggest that secondary forests were nitrogen limited, but acacia plantations were less nitrogen limited. Leguminous tree plantations may increase nitrogen cycling, resulting in greater N2O emissions from the soil. However, on a global warming potential basis, N2O emissions from acacia plantation soils accounted for less than 10% of the carbon uptake by plants. Nevertheless, because of the spread of leguminous tree plantations in Asia, the importance of N2O emissions from leguminous tree stands will increase in the coming decades.

  11. Solubility and Diffusivity of Acid Gases (CO2, N2O) in Aqueous Alkanolamine Solutions

    NARCIS (Netherlands)

    Versteeg, Geert F.; Swaaij, Wim P.M. van

    1988-01-01

    Solubility and diffusivity of N2O and CO2 in water were determined as a function of temperature from the results published in the open literature, and new data were measured in the present work. The solubility of N2O in several aqueous alkanolamine (DEA, DIPA, DMMEA, and DIPA) solutions at various

  12. Density, Viscosity, Solubility, and Diffusivity of N2O in Aqueous Amino Acid Salt Solutions

    NARCIS (Netherlands)

    Kumar, P. Senthil; Hogendoorn, J.A.; Feron, P.H.M.; Versteeg, G.F.

    2001-01-01

    Solubility and diffusivity of N2O in aqueous solutions of potassium taurate are reported over a wide range of concentration and temperature. Also, the solubility of N2O in aqueous potassium glycinate solution is reported at 295 K. The ion specific constants are reported for taurate and glycinate

  13. Application of the DNDC model to predict emissions of N2O from Irish agriculture

    DEFF Research Database (Denmark)

    Abdalla, M.; Wattenbach, M.; Smith, P.

    2009-01-01

    temperature as the main determinant of N2O flux, an increase in mean daily air temperature of 1.5 °C resulting in almost a 65% increase in the annual cumulative flux. This is interesting as with future global warming, N2O flux from the soil will have a strong positive feedback. It can be concluded that DNDC...

  14. The estimation of N2O emissions from municipal solid waste incineration facilities: The Korea case

    International Nuclear Information System (INIS)

    Park, Sangwon; Choi, Jun-Ho; Park, Jinwon

    2011-01-01

    The greenhouse gases (GHGs) generated in municipal solid waste (MSW) incineration are carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O). In South Korea case, the total of GHGs from the waste incineration facilities has been increasing at an annual rate 10%. In these view, waste incineration facilities should consider to reduce GHG emissions. This study is designed to estimate the N 2 O emission factors from MSW incineration plants, and calculate the N 2 O emissions based on these factors. The three MSW incinerators examined in this study were either stoker or both stoker and rotary kiln facilities. The N 2 O concentrations from the MSW incinerators were measured using gas chromatography-electron capture detection (GC-ECD) equipment. The average of the N 2 O emission factors for the M01 plant, M02 plant, and M03 plant are 71, 75, and 153 g-N 2 O/ton-waste, respectively. These results showed a significant difference from the default values of the intergovernmental panel on climate change (IPCC), while approaching those values derived in Japan and Germany. Furthermore, comparing the results of this study to the Korea Energy Economics Institute (KEEI) (2007) data on waste incineration, N 2 O emissions from MSW incineration comprised 19% of the total N 2 O emissions.

  15. The estimation of N2O emissions from municipal solid waste incineration facilities: The Korea case.

    Science.gov (United States)

    Park, Sangwon; Choi, Jun-Ho; Park, Jinwon

    2011-08-01

    The greenhouse gases (GHGs) generated in municipal solid waste (MSW) incineration are carbon dioxide (CO(2)), methane (CH(4)), and nitrous oxide (N(2)O). In South Korea case, the total of GHGs from the waste incineration facilities has been increasing at an annual rate 10%. In these view, waste incineration facilities should consider to reduce GHG emissions. This study is designed to estimate the N(2)O emission factors from MSW incineration plants, and calculate the N(2)O emissions based on these factors. The three MSW incinerators examined in this study were either stoker or both stoker and rotary kiln facilities. The N(2)O concentrations from the MSW incinerators were measured using gas chromatography-electron capture detection (GC-ECD) equipment. The average of the N(2)O emission factors for the M01 plant, M02 plant, and M03 plant are 71, 75, and 153g-N(2)O/ton-waste, respectively. These results showed a significant difference from the default values of the intergovernmental panel on climate change (IPCC), while approaching those values derived in Japan and Germany. Furthermore, comparing the results of this study to the Korea Energy Economics Institute (KEEI) (2007) data on waste incineration, N(2)O emissions from MSW incineration comprised 19% of the total N(2)O emissions. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

  16. Spatial and temporal variability of N2O emissions in a subtropical forest catchment in China

    Directory of Open Access Journals (Sweden)

    J. Zhu

    2013-03-01

    Full Text Available Subtropical forests in southern China have received chronically large amounts of atmogenic nitrogen (N, causing N saturation. Recent studies suggest that a significant proportion of the N input is returned to the atmosphere, in part as nitrous oxide (N2O. We measured N2O emission fluxes by closed chamber technique throughout two years in a Masson pine-dominated headwater catchment with acrisols (pH ~ 4 at Tieshanping (Chongqing, SW China and assessed the spatial and temporal variability in two landscape elements typical for this region: a mesic forested hillslope (HS and a hydrologically connected, terraced groundwater discharge zone (GDZ in the valley bottom. High emission rates of up to 1800 μg N2O-N m−2 h−1 were recorded on the HS shortly after rain storms during monsoonal summer, whereas emission fluxes during the dry winter season were generally low. Overall, N2O emission was lower in GDZ than on HS, rendering the mesic HS the dominant source of N2O in this landscape. Temporal variability of N2O emissions on HS was largely explained by soil temperature (ST and moisture, pointing at denitrification as a major process for N removal and N2O production. The concentration of nitrate (NO3− in pore water on HS was high even in the rainy season, apparently never limiting denitrification and N2O production. The concentration of NO3− decreased along the terraced GDZ, indicating efficient N removal, but with moderate N2O-N loss. The extrapolated annual N2O fluxes from soils on HS (0.54 and 0.43 g N2O-N m−2 yr−1 for a year with a wet and a dry summer, respectively are among the highest N2O fluxes reported from subtropical forests so far. Annual N2O-N emissions amounted to 8–10% of the annual atmogenic N deposition, suggesting that forests on acid soils in southern China are an important, hitherto overlooked component of the anthropogenic N2O budget.

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

    Directory of Open Access Journals (Sweden)

    Alain Brauman

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  19. Assessing drivers of N2O production in California tomato cropping systems.

    Science.gov (United States)

    Kennedy, Taryn; Decock, Charlotte; Six, Johan

    2013-11-01

    Environmental conditions and agricultural management events affect the availability of substrates and microbial habitat required for the production and consumption of nitrous oxide (N2O), influencing the temporal and spatial variability of N2O fluxes from soil. In this study, we monitored for diurnal and event-related patterns in N2O emissions in the field, evaluated how substrate availability influenced denitrification, and assessed N2O reduction potential following major events in two tomato (Lycopersicon esculentum) management systems on clay loam soils: 1) conventional (sidedress fertilizer injection, furrow irrigation, and standard tillage) and 2) integrated (fertigation, subsurface drip irrigation, and reduced tillage). Potential denitrification activity, substrate limitation, and reduction to N2 were measured with an anaerobic slurry technique. In the field, we found no consistent diurnal patterns. This suggests that controlling factors that vary on an event-basis overrode effects of diurnally variable controls on N2O emissions. The lack of consistent diurnal patterns also indicates that measuring N2O emissions once per day following major events is sufficient to adequately assess annual N2O emissions in those systems. Nitrous oxide emissions varied per event and across functional locations in both systems. This illustrates that mechanisms underlying N2O emissions vary at relatively small temporal and spatial scales and demonstrates the importance of studying N2O emissions in the context of events and functional locations. In the conventional system, N2O fluxes were high [74.2±43.9-390.5±90.1 μg N2O-N m(-2) h(-1)] and N2O reduction potential was significant. Both management systems exhibited carbon limitation on denitrification rates; and rates were N limited in the third fertigation event in the integrated system. Our findings suggest that denitrification is strongly contributing to high N2O emissions in conventional tomato cropping systems in California

  20. Bark vegetation contributes to nitrous oxide (N2O) deposition by mature beech trees

    Science.gov (United States)

    Machacova, Katerina; Maier, Martin; Svobodova, Katerina; Lang, Friederike; Urban, Otmar

    2017-04-01

    Nitrous oxide (N2O) contributes to the acceleration of the greenhouse effect. Accordingly, there is an urgent need to investigate the natural capability of forest ecosystems to exchange N2O with the atmosphere. While the soils of temperate forests were shown to be a significant natural source of N2O, trees have been so far overlooked in the forest N2O inventories. Trees are known, however, to emit this gas, especially at very high N2O concentration in soil. We determined the N2O fluxes in mature beech trees (Fagus sylvatica) in two upland mountain forests (White Carpathians, CZ; Black Forest, DE) with predominant soil N2O uptake. To understand these fluxes, N2O exchange in photoautotrophic organisms associated with beech stems (lichens, mosses, and algae) was further investigated under laboratory conditions. Fluxes were measured in situ in June and July 2015 using static chamber systems followed by chromatographic and photo-acoustic analyses of N2O concentration changes. In both forests studied, all beech stems deposited N2O from the atmosphere. Such consistent uptake of N2O by stems represents a novel and unique finding which is in the contrast to current limited studies presenting trees as N2O emitters. The mean stem deposition rates were significantly higher in the White Carpathians (-3.8 μg N2O m-2 stem area h-1) than in the Black Forest (-2.3 μg N2O m-2 h-1). The forest floor was a strong sink for N2O (White Carpathians: -111, Black Forest: -81 μg N2O m-2 soil area h-1). The N2O concentration profiles within the soil did not identify any apparent production or consumption processes. Photoautotrophic organisms (lichens, mosses, and algae), largely associated with the bark of studied trees, were collected for further analyses. The detailed incubation experiments revealed that all sampled organisms deposited N2O under the conditions of full rehydration and air temperature of 25˚ C. Their deposition rates per unit area were in the same order of magnitude as

  1. Pathways and Controls of N2O Production in Nitritation-Anammox Biomass

    DEFF Research Database (Denmark)

    Ma, Chun; Jensen, Marlene Mark; Smets, Barth F.

    2017-01-01

    of N2O production from hydroxylamine oxidation at low O2 was unexpected and suggests that more than one enzymatic pathway may be involved in this process. N2O production by hydroxylamine oxidation was further stimulated by NH4+, whereas nitrifier denitrification at low O2 levels was stimulated by NO2...... contributed substantially to N2O accumulation across a wide range of conditions with varying concentrations of O2, NH4+, and NO2-. The O2 concentration exerted the strongest control on net N2O production with both production pathways stimulated by low O2, independent of NO2- concentrations. The stimulation......- at levels as low as 0.2 mM. Our study shows that 15N and 18O isotope labeling is a useful approach for direct quantification of N2O production pathways applicable to diverse environments....

  2. Investigations on measures to reduce nitrous oxide (N2O); Asanka chisso (N2O) no teigen taisaku ni kansuru chosa

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-03-01

    Discussions were given on measures to reduce N2O as part of the measures to prevent global warming. Nitrous oxide has a long atmospheric lifetime of 150 years, and its greenhouse warming potential will increase by 310 times that of CO2 after 100 years. It can also be a cause of ozone layer destruction. Nitrous oxide is estimated to have influence of about 10% as compared with CO2 even under the present conditions. Discharge of N2O from manufacturing process of adipic acid is aimed to be eliminated totally by 1998. Improvement in efficiency of combustion of fossil fuels and wastes serves most effectively to reduce not only N2O but also CO2. Nitrous oxide generated in sewage treatment as in sewage purifier may be reduced if the batch process is turned into a continuous process, but assistance from policy side would be required for wider adoption of the process conversion. No environmental regulations are applicable to N2O, whereas a problem is present that the number of system installation would not grow because of economic reasons even if the system is feasible technically. Another problem is that the N2O reducing technology is in trade-off relation with other warming gases such as NOx and methane. Comprehensive technological evaluations aimed at optimization must be moved forward in the future. 236 refs., 102 figs., 78 tabs.

  3. N2O emission from plant surfaces - light stimulated and a global phenomenon.

    Science.gov (United States)

    Mikkelsen, Teis; Bruhn, Dan; Ambus, Per

    2017-04-01

    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-2 h-1, mostly due to the UV component. 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. Literature: Mikkelsen TN, Bruhn D & Ambus P. (2016). Solar UV Irradiation-Induced Production of Greenhouse Gases from Plant Surfaces: From Leaf to Earth. Progress in Botany, DOI 10.1007/124_2016_10. Bruhn D, Albert KR, Mikkelsen TN & Ambus P. (2014). UV-induced N2O emission from plants. Atmospheric Environment 99, 206-214.

  4. Effect of Exogenous Nitrogen Addition on Nitrous Oxide N 2 O Emissions from Wetland Soil

    Directory of Open Access Journals (Sweden)

    SHI Hao-xian

    2014-10-01

    Full Text Available It is important to make sure key nitrogen driving N2O emission source from wetland soil for efficient N2O emission reduction. In lab-oratory, the temperature and humidity were kept constant to study effect from different forms of exogenous N on N2O emissions from wetland soil by gas chromatography. The results showed that all groups of exogenous N inputs increased N2O emissions from wetland soil in contrast to CK group(4.4 mg·m -3. Under the group urea(Ualone and the combination of urea with ammonium nitrate(UANin a 1:1 concentration ra-tio, the change of N2O emissions showed a unimodal trend, first increased and then decreased, the peak value 10.6 mg· m -3 and 229.0 mg·m -3 of N2 O emissions corresponded to U and of UAN, respectively. While N2O emissions showed an upward trend for ammonium nitrate(ANalone, within the range from 32.6 mg·m -3 to 111.0 mg·m -3 N2O emissions. All exogenous N treatments increased N2O emissions more than CK,UAN combination>AN alone>U alone. This provided a scientific basis for predicting greenhouse effect caused by N fertilizer in wetland soil from farming-pastoral transition zone, as well as a reference for effective reducing N2 O emissions from wetlands in Inner Mongolia Plateau.

  5. Symbiotic relationships between soil fungi and plants reduce N2O emissions from soil.

    Science.gov (United States)

    Bender, S Franz; Plantenga, Faline; Neftel, Albrecht; Jocher, Markus; Oberholzer, Hans-Rudolf; Köhl, Luise; Giles, Madeline; Daniell, Tim J; van der Heijden, Marcel Ga

    2014-06-01

    N2O is a potent greenhouse gas involved in the destruction of the protective ozone layer in the stratosphere and contributing to global warming. The ecological processes regulating its emissions from soil are still poorly understood. Here, we show that the presence of arbuscular mycorrhizal fungi (AMF), a dominant group of soil fungi, which form symbiotic associations with the majority of land plants and which influence a range of important ecosystem functions, can induce a reduction in N2O emissions from soil. To test for a functional relationship between AMF and N2O emissions, we manipulated the abundance of AMF in two independent greenhouse experiments using two different approaches (sterilized and re-inoculated soil and non-mycorrhizal tomato mutants) and two different soils. N2O emissions were increased by 42 and 33% in microcosms with reduced AMF abundance compared to microcosms with a well-established AMF community, suggesting that AMF regulate N2O emissions. This could partly be explained by increased N immobilization into microbial or plant biomass, reduced concentrations of mineral soil N as a substrate for N2O emission and altered water relations. Moreover, the abundance of key genes responsible for N2O production (nirK) was negatively and for N2O consumption (nosZ) positively correlated to AMF abundance, indicating that the regulation of N2O emissions is transmitted by AMF-induced changes in the soil microbial community. Our results suggest that the disruption of the AMF symbiosis through intensification of agricultural practices may further contribute to increased N2O emissions.

  6. Biochar reduces N2O emissions from soils: A meta-analysis

    Science.gov (United States)

    Schirrmann, Michael; Cayuela, Maria Luz; Fuertes-Mendizábal, Teresa; Estavillo, José-María; Ippolito, Jim; Spokas, Kurt; Novak, Jeff; Kammann, Claudia; Wrage-Mönnig, Nicole; Borchard, Nils

    2017-04-01

    Global efforts to mitigate climate change and to increase food security are challenging. Technologies that reduce greenhouse gas emissions from agriculture while increasing crop yields simultaneously are not well characterized for their efficiency. For instance, biochar used to sequester carbon and to increase crop yields also alters the soil nitrogen cycle. This in turn affects N2O emissions from soil, where N2O has a higher global warming potential than emitted CO2. However, the mechanisms of biochar regarding the N2O emission process are not well understood due to complex interactions between soil organic and inorganic materials and their impact on the physical soil structure. To further understand the complex relationship, a single experimental study may not provide critical answers. Therefore, we conducted a meta-analysis by reviewing literature published between 2010 and 2016 that focused on N2O emission from soils amended with biochars. A meta-analysis is a quantitative technique that allows estimating an overall treatment effect from many divergent research experiments. In our case, we included 92 publications that contained a total of 437 comparisons between biochar treated soils and biochar non-treated soils. We used a random effects model and bootstrapping with 1000 intervals to estimate the general percentage increase or decrease of N2O emission through biochar amendment. Our results showed that biochar treatment leads to a significant decrease of N2O emissions between 33% and 45%. This promising result highlights the need to increase investigations to more fully assess (i) the multitude of mechanisms involved in the observed N2O emission reductions such as soil pH changes, alterations in the soil microbial community and soil N cycling, a shift in the ratio of denitrifier end products (N2O/(N2O+N2) ratio) or nitrate capture by biochar particles, and (ii) the impact of biochar characteristics, soil properties and land use types on the multiple mechanisms

  7. Functional diversity of soil invertebrates: a potential tool to explain N2O emission?

    Science.gov (United States)

    Lubbers, Ingrid; De Deyn, Gerlinde; Drake, Harold; Hunger, Sindy; Oppermann, Timo; van Groenigen, Jan Willem

    2017-04-01

    Soil biota play a crucial role in the mineralization of nutrients from organic material. However, they can thereby increase emissions of the potent greenhouse gas nitrous oxide (N2O). Our current lack of understanding of the factors controlling N2O production and emission is impeding the development of effective mitigation strategies. It is the challenge to control N2O emissions from production systems without reducing crop yield, and diversity of soil fauna may play a key role. A high functional diversity of soil invertebrates is known to stimulate nitrogen mineralization and thereby plant growth, however, it is unknown whether a high functional diversity of soil invertebrates can concurrently diminish N2O emissions. We hypothesized that increased functional diversity of soil invertebrates reduces faunal-induced N2O emissions by facilitating more complete denitrification through (i) stimulating the activity of denitrifying microbes, and (ii) affecting the distribution of micro and macro pores, creating more anaerobic reaction sites. Using state-of-the-art X-ray tomography and next-generation sequencing, we studied effects of functional diversity on soil structural properties and the diversity of the microbial community (16S rRNA genes and 16S rRNA), and linked these to soil N2O emissions. In a 120-day study we found that the functional composition of the soil invertebrate community determined N2O emissions: earthworm activity was key to faunal-induced N2O emissions (a 32-fold increase after 120 days, P<0.001). No proof was found to explain faunal-induced N2O emissions through differences in stimulated microbial activity. On the other hand, soil structural properties (mean pore size, pore size distribution) were found to be radically altered by earthworm activity. We conclude that the presence of a few functional groups (ecosystem engineers) is more important than overall increased functional diversity in explaining faunal-affected N2O emissions.

  8. Are Isotopologue Signatures of N2O from Bacterial Denitrifiers Indicative of NOR Type?

    Science.gov (United States)

    Well, R.; Braker, G.; Giesemann, A.; Flessa, H.

    2010-12-01

    Nitrous oxide (N2O) fluxes from soils result from its production by nitrification and denitrification and reduction during denitrification. The structure of the denitrifying microbial community contributes to the control of net N2O fluxes. Although molecular techniques are promising for identifying the active community of N2O producers, there are few data until now because methods to explore gene expression of N2O production are laborious and disregard regulation of activity at the enzyme level. The isotopologue signatures of N2O including δ18O, average δ15N (δ15Nbulk) and 15N site preference (SP = difference in δ15N between the central and peripheral N positions of the asymmetric N2O molecule) have been used to estimate the contribution of partial processes to net N2O fluxes to the atmosphere. However, the use of this approach to study N2O dynamics in soils requires knowledge of isotopic signatures of N2O precursors and isotopologue fractionation factors (ɛ) of all processes of N2O production and consumption. In contrast to δ18O and δ15Nbulk, SP is independent of precursor signatures and hence is a promising parameter here. It is assumed that SP of produced N2O is almost exclusively controlled by the enzymatic isotope effects of NO reductases (NOR). These enzymes are known to be structurally different between certain classes of N2O producers with each class causing different isotope effects (Schmidt et al., 2004). The NH2OH-to-N2O step of nitrifiers and the NO3-to-N2O step of fungal denitrifiers are associated with large site-specific 15N effects with SP of 33 to 37 ‰ (Sutka et al., 2006, 2008) while the few tested species of gram-negative bacterial denitrifiers (cNOR group) exhibited low SP of -5 to 0‰ (Sutka et al., 2006; Toyoda et al., 2005). The aim of our study was to determine site-specific fractionation factors of the NO3-to-N2O step (ɛSP) for several species of denitrifiers representing each of the known NOR-types of bacteria, i.e. cNOR, q

  9. TCNE-modified graphene as an adsorbent for N2O molecule: a DFT study.

    Science.gov (United States)

    Rastegar, Somayeh F; Osouleddini, Noushin

    2017-11-22

    Adsorption behavior of nitrous oxide (N 2 O) on pristine graphene (PG) and tetracyanoethylene (TCNE) modified PG surfaces is investigated using density functional theory. A number of initial adsorbate geometries are considered on both surfaces and the most stable ones are chosen upon calculation of the adsorption energies (E ads ). N 2 O is found to adsorb in a weakly exoergic process (E ads  ∼ -3.18 kJ mol -1 ) at the equilibrium distance of 3.52 Å on the PG surface. N 2 O adsorption can be greatly enhanced with the presence of a TCNE molecule (E ads  = -87.00 kJ mol -1 ). Mulliken charge analysis confirms that adsorption of N 2 O is not accompanied by distinct charge transfer from the surfaces to the molecule (˂ 0.001 │e│ for each case). Moreover, on the basis of calculated changes in the HOMO/LUMO energy gap, it is found that electronic properties of PG and TCNE modified PG are not sensitive toward adsorption of N 2 O, indicating that both surfaces are not good enough to introduce as an N 2 O detector. However, the considerable amount of E ads in TCNE modified PG can be a guide to the design of graphene-based adsorbents for N 2 O capture.

  10. Extreme emission of n2o from tropical wetland soil (pantanal, South America)

    DEFF Research Database (Denmark)

    Møller, Lars Liengård Holten; Nielsen, Lars Peter; Revsbech, Niels Peter

    2012-01-01

    Nitrous oxide (N(2)O) is an important greenhouse gas and ozone depleter, but the global budget of N(2)O remains unbalanced. Currently, ~25% of the global N(2)O emission is ascribed to uncultivated tropical soils, but the exact locations and controlling mechanisms are not clear. Here we present....... In 2010, 10 sites were screened for in situ fluxes of N(2)O and soil [Formula: see text] content. The in situ fluxes of N(2)O were comparable to fluxes from heavily fertilized forests or agricultural soils. An important parameter affecting N(2)O emission rate was precipitation, inducing peak emissions...... of >3¿mmol¿N(2)O¿m(-2)¿day(-1), while the mean daily flux was 0.43¿±¿0.03¿mmol¿N(2)O¿m(-2)¿day(-1). Over 170¿days of the drained period, we estimated non-wetted drained soil to contribute 70.0¿mmol¿N(2)O¿m(-2), while rain-induced peak events contributed 9.2¿mmol¿N(2)O¿m(-2), resulting in a total N(2)O...

  11. The isotopic fingerprint of the pre-industrial and the anthropogenic N2O source

    Directory of Open Access Journals (Sweden)

    T. Röckmann

    2003-01-01

    Full Text Available We have performed high-precision measurements of the 18O and position dependent 15N isotopic composition of N2O from Antarctic firn air samples. By comparing these data to simulations carried out with a firn air diffusion model, we have reconstructed the temporal evolution of the N2O isotope signatures since pre-industrial times. The heavy isotope content of atmospheric N2O is presently decreasing for all signatures at rates of about -0.038 %o yr -1 for 1d15N, -0.046 %o yr -1 for 2d 15N and -0.025 %o yr -1 for d18O. The total decrease since pre-industrial times is estimated to be about -1.8%o for 1d15N at both positions and -2.2%o for 2d15N. Isotope budget calculations using these trends and recent stratospheric measurements allow to isotopically characterize the present and the pre-industrial global average N2O source, as well as the additional N2O emissions that have caused the global N2O increase since pre-industrial times. The increased fluxes from the depleted surface sources alone are insufficient to explain the inferred temporal isotope changes. In addition, the global average N2O source signature is calculated to be significantly depleted today relative to the pre-industrial value, in agreement with recent indications from soil emission measurements.

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

    Science.gov (United States)

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

    2015-06-15

    This study examines the effects of temperature on nitrous oxide (N2O) emissions in a bench-scale intensive aquaculture system rearing Koi fish. The water temperature varied from 15 to 24 °C at interval of 3 °C. Both volumetric and specific rate for nitrification and denitrification declined as the temperature decreased. The concentrations of ammonia and nitrite, however, were lower than the inhibitory level for Koi fish regardless of temperature. The effects of temperature on N2O emissions were significant, with the emission rate and emission factor increasing from 1.11 to 1.82 mg N2O-N/d and 0.49 to 0.94 mg N2O-N/kg fish as the temperature decreased from 24 to 15 °C. A global map of N2O emission from aquaculture was established by using the N2O emission factor depending on temperature. This study demonstrates that N2O emission from aquaculture is strongly dependent on regional water temperatures as well as on fish production. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. High-Precision Measurement of N2O Concentration in Ice Cores.

    Science.gov (United States)

    Ryu, Yeongjun; Ahn, Jinho; Yang, Ji-Woong

    2018-01-16

    Atmospheric nitrous oxide (N 2 O) is a greenhouse gas and ozone-depleting substance whose emissions are substantially perturbed by current human activities. Although air trapped in polar ice cores can provide direct information about N 2 O evolution, analytical precision was not previously sufficient for high temporal resolution studies. In this work, we present a highly improved analytical technique with which to study N 2 O concentrations in ancient-air-trapped ice cores. We adopt a melt-refreezing method to extract air and use a gas chromatography-electron capture detector (GC-ECD) to determine N 2 O concentrations. The GC conditions are optimized to improve the sensitivity for detecting N 2 O. Retrapped N 2 O in ice during the extraction procedure is precisely analyzed and corrected. We confirmed our results using data from the Styx Glacier ice core in Antarctica by comparing them with the results of a dry-extraction method. The precision estimated from the pooled standard deviation of replicated measurements of the Styx ice core was 1.5 ppb for ∼20 g of ice, a smaller sample of ice than was used in previous studies, showing a significant improvement in precision. Our preliminary results from the Styx Glacier ice core samples have the potential to define small N 2 O variations (a few parts per billion) at centennial time scales.

  14. Update on N2O4 Molecular Sieving with 3A Material at NASA/KSC

    Science.gov (United States)

    Davis, Chuck; Dorn, Claudia

    2000-01-01

    During its operational life, the Shuttle Program has experienced numerous failures in the Nitrogen Tetroxide (N2O4) portion of Reaction Control System (RCS), many of which were attributed to iron-nitrate contamination. Since the mid-1980's, N2O4 has been processed through a molecular sieve at the N2O4 manufacturer's facility which results in an iron content typically less than 0.5 parts-per-million-by-weight (ppmw). In February 1995, a Tiger Team was formed to attempt to resolve the iron nitrate problem. Eighteen specific actions were recommended as possibly reducing system failures. Those recommended actions include additional N2O4 molecular sieving at the Shuttle launch site. Testing at NASA White Sands Test Facility (WSTF) determined an alternative molecular sieve material could also reduce the water-equivalent content (free water and HNO3) and thereby further reduce the natural production of iron nitrate in N2O4 while stored in iron-alloy storage tanks. Since April '96, NASA Kennedy Space Center (KSC) has been processing N2O4 through the alternative molecular sieve material prior to delivery to Shuttle launch pad N2O4 storage tanks. A new, much larger capacity molecular sieve unit has also been used. This paper will evaluate the effectiveness of N2O4 molecular sieving on a large-scale basis and attempt to determine if the resultant lower-iron and lower-water content N2O4 maintains this new purity level in pad storage tanks and shuttle flight systems.

  15. N2O emission from organic barley cultivation as affected by green manure management

    Directory of Open Access Journals (Sweden)

    P. Dörsch

    2012-07-01

    Full Text Available Legumes are an important source of nitrogen in stockless organic cereal production. However, substantial amounts of N can be lost from legume-grass leys prior to or after incorporation as green manure (GM. Here we report N2O emissions from a field experiment in SE Norway exploring different green manure management strategies: mulching versus removal of grass-clover herbage during a whole growing season and return as biogas residue to a subsequent barley crop. Grass-clover ley had small but significantly higher N2O emissions as compared with a non-fertilised cereal reference during the year of green manure (GM production in 2009. Mulching of herbage induced significantly more N2O emission (+0.37 kg N2O-N ha−1 throughout the growing season than removing herbage. In spring 2010, all plots were ploughed (with and without GM and sown with barley, resulting in generally higher N2O emissions than during the previous year. Application of biogas residue (60 kg NH4+-N + 50 kg organic N ha−1 before sowing did not increase emissions neither when applied to previous ley plots nor when applied to previously unfertilised cereal plots. Ley management (mulching vs. removing biomass in 2009 had no effect on N2O emissions during barley production in 2010. In general, GM ley (mulched or harvested increased N2O emissions relative to a cereal reference with low mineral N fertilisation (80 kg N ha−1. Based on measurements covering the growing season 2010, organic cereal production emitted 95 g N2O-N kg−1 N yield in barley grain, which was substantially higher than in the cereal reference treatment with 80 kg mineral N fertilisation (47 g N2O-N kg−1 N yield in barley grain.

  16. N2O Emission from Managed Soil Under Different Crops in Rainfed Area, Central Java

    Directory of Open Access Journals (Sweden)

    Miranti Ariani

    2016-05-01

    Full Text Available N2O emission from agriculture has been assumed to increase by 30-35% until 2030. This gas has a major contribute to the emission from agriculture. N2O emission from managed soils is the 2nd contributor to green house gas (GHG emission from agriculture in Indonesia. Rainfed area requested high management input. This research aimed to examine N2O emission from different crops in the rainfed area and its affecting factors, also to identify things that need to be considered in conducting N2O measurement from managed soil. Research conducted in Pati and Blora District, Central Java Province. Four (4 different experimental sites with 4 different crops were chosen. Those were mung bean, rubber plantation and sugarcane which located within Pati District, and maize crop which located in Blora District. No treatment was applied. Gas samples were taken following the day after fertilizing. Daily N2O fluxes from managed soil in tropical land of Indonesia determine by several factors, which are: days after fertilizing, fertilizer type and dosage, previous land use, growth phase of crops, sampling point and soil characteristic. The peak time was mostly influenced by crop type. Maize has the highest N2O daily fluxes with the range of 311.9 - 9651.6 μg N2O m-2day-1 and rubber plantation has the lowest with the range of 16.1 - 2270.7 μg N2O m-2day-1. Measurement of N2O from managed soil to determine annual emissions should be done at all crop types, soil types, considering crops growth phase and also high sampling frequency to prevent an over or under estimation.

  17. Emissions of N2O from peat soils under different cropping systems

    Science.gov (United States)

    Norberg, Lisbet; Berglund, Örjan; Berglund, Kerstin

    2016-04-01

    Drainage of peatlands for agriculture use leads to an increase in nitrogen turnover rate causing emissions of N2O to the atmosphere. Agriculture contributes to a substantial part of the anthropogenic emissions of N2O therefore mitigation options for the farmers are important. Here we present a field study with the aim to investigate if the choice of cropping system can mitigate the emission of N2O from cultivated organic soils. The sites used in the study represent fen peat soils with a range of different soil properties located in different parts of southern Sweden. All sites are on active farms with good drainage. N2O emissions from the soil under two different crops grown on the same field, with the same soil type, drainage intensity and weather conditions, are compared by gas sampling. The crops included are oat, barley, carrot, potato and grassland. Three or four sampling occasions during the growing season in 2010 were carried out with static chambers. The N2O emission is calculated from the linear increase of gas concentration in the chamber headspace during the incubation time of 40 minutes. Parallel to the gas sampling soil temperature and soil moisture are measured and some soil properties determined. The result from the gas sampling and measurements show no significant difference in seasonal average N2O emission between the compared crops at any site. There are significant differences in N2O emissions between the compared crops at some of the single sampling occasions but the result vary and no crop can be pointed out as a mitigation option. The seasonal average N2O emissions varies from 16±17 to 1319±1971 μg N2O/m2/h with peaks up to 3317 μg N2O/m2/h. The N2O emission rate from peat soils are determined by other factors than the type of crops grown on the field. The emission rates vary during the season and especially between sites. Although all sites are fen peat soil the soil properties are different, e.g. carbon content varies between 27-43% and

  18. Combining organic and inorganic nitrogen fertilisation reduces N2O emissions from cereal crops

    DEFF Research Database (Denmark)

    Nyamadzawo, George; Shi, Yeufeng; Chirinda, Ngonidzashe

    2017-01-01

    maize (Zea mays L.) and winter wheat (Triticum aestivum L.) fields amended with inorganic, organic N and a combination of both sources (integrated management), in tropical (Zimbabwe) and temperate (China) climatic conditions. In Zimbabwe N2O emissions were measured from maize plots, while in China......, integrated nutrient management resulted in lower N2O emissions compared to inorganic fertilizers which had higher total and yield-scale N2O emissions. We conclude that by combining organic and inorganic N sources, smallholder farmers in both China and Zimbabwe, and other countries with similar climatic...

  19. Variations in atmospheric N2O concentration during abrupt climatic changes

    Science.gov (United States)

    Fluckiger; Dallenbach; Blunier; Stauffer; Stocker; Raynaud; Barnola

    1999-07-09

    Nitrous oxide (N2O) is an important greenhouse gas that is presently increasing at a rate of 0.25 percent per year. Records measured along two ice cores from Summit in Central Greenland provide information about variations in atmospheric N2O concentration in the past. The record covering the past millennium reduces the uncertainty regarding the preindustrial concentration. Records covering the last glacial-interglacial transition and a fast climatic change during the last ice age show that the N2O concentration changed in parallel with fast temperature variations in the Northern Hemisphere. This provides important information about the response of the environment to global climatic changes.

  20. Extreme Emission of N2O from Tropical Wetland Soil (Pantanal, South America)

    Science.gov (United States)

    Liengaard, Lars; Nielsen, Lars Peter; Revsbech, Niels Peter; Priemé, Anders; Elberling, Bo; Enrich-Prast, Alex; Kühl, Michael

    2013-01-01

    Nitrous oxide (N2O) is an important greenhouse gas and ozone depleter, but the global budget of N2O remains unbalanced. Currently, ∼25% of the global N2O emission is ascribed to uncultivated tropical soils, but the exact locations and controlling mechanisms are not clear. Here we present the first study of soil N2O emission from the Pantanal indicating that this South American wetland may be a significant natural source of N2O. At three sites, we repeatedly measured in situ fluxes of N2O and sampled porewater nitrate (NO3-) during the low water season in 2008 and 2009. In 2010, 10 sites were screened for in situ fluxes of N2O and soil NO3- content. The in situ fluxes of N2O were comparable to fluxes from heavily fertilized forests or agricultural soils. An important parameter affecting N2O emission rate was precipitation, inducing peak emissions of >3 mmol N2O m−2 day−1, while the mean daily flux was 0.43 ± 0.03 mmol N2O m−2 day−1. Over 170 days of the drained period, we estimated non-wetted drained soil to contribute 70.0 mmol N2O m−2, while rain-induced peak events contributed 9.2 mmol N2O m−2, resulting in a total N2O emission of 79.2 mmol N2O m−2. At the sites of repeated sampling, the pool of porewater nitrate varied (0.002-7.1μmolNO3-gdW-1) with higher concentrations of NO3- (p Pantanal, we suggest that this undisturbed tropical wetland potentially contributes ∼1.7% to the global N2O emission budget, a significant single source of N2O. PMID:23293634

  1. Emission factors for organic fertilizer-induced N2O emissions from Japanese agricultural soils

    Science.gov (United States)

    Sano, T.; Nishina, K.; Sudo, S.

    2013-12-01

    1. Introduction Agricultural fields are significant sources of nitrous oxide (N2O), which is one of the important greenhouse gases with a contribution of 7.9% to the anthropogenic global warming (IPCC, 2007). Direct fertilizer-induced N2O emission from agricultural soil is estimated using the emission factor (EF). National greenhouse gas inventory of Japan defines direct EF for N2O associated with the application of chemical and organic fertilizers as the same value (0.62%) in Japanese agricultural fields. However, it is necessary to estimate EF for organic fertilizers separately, because there are some differences in factors controlling N2O emissions (e.g. nutrient content) between chemical and organic fertilizers. The purpose of this study is to estimate N2O emissions and EF for applied organic fertilizers in Japanese agricultural fields. 2. Materials and Methods We conducted the experiments at 10 prefectural agricultural experimental stations in Japan (Yamagata, Fukushima, Niigata, Ibaraki, Aichi, Shiga, Tokushima, Nagasaki, Kumamoto, and Kagoshima) to consider the variations of cultivation and environmental conditions among regions. Field measurements had been conducted for 2-2.5 years during August 2010-April 2013. Each site set experimental plots with the applications of composted manure (cattle, swine, and poultry), chemical fertilizer, and non-nitrogen fertilizer as a control. The annual amount of applied nitrogen ranged from 16 g-N m-2 y-1 to 60 g-N m-2 y-1 depending on cropping system and cultivated crops (e.g. cabbage, potato) at each site. N2O fluxes were measured using a closed-chamber method. N2O concentrations of gas samples were measured with gas chromatography. The EF value of each fertilizer was calculated as the N2O emission from fertilizer plots minus the background N2O emission (emission from a control plot), and was expressed as a percentage of the applied nitrogen. The soil NH4+ and NO3-, soil temperature, precipitation, and WFPS (water

  2. HIRDLS/Aura Level 3 Nitrous Oxide (N2O) Zonal Fourier Coefficients V007

    Data.gov (United States)

    National Aeronautics and Space Administration — The "HIRDLS/Aura Level 3 Nitrous Oxide (N2O) Zonal Fourier Coefficients" version 7 data product (H3ZFCN2O) contains the entire mission (~3 years) of HIRDLS data...

  3. MLS/Aura L2 Nitrous Oxide (N2O) Mixing Ratio V003

    Data.gov (United States)

    National Aeronautics and Space Administration — ML2N2O is the EOS Aura Microwave Limb Sounder (MLS) standard product for nitrous oxide derived from radiances measured primarily by the 640 GHz radiometer (Band 12)...

  4. A novel fuzzy-logic control strategy minimizing N2O emissions

    DEFF Research Database (Denmark)

    Boiocchi, Riccardo; Gernaey, Krist; Sin, Gürkan

    2017-01-01

    A novel control strategy for achieving low N2O emissions and low effluent NH4+ concentration is here proposed. The control strategy uses the measurements of ammonium and nitrate concentrations in inlet and outlet of the aerobic zone of a wastewater treatment plant to calculate a ratio indicating...... was implemented using the fuzzy logic approach. It was comprehensively tested for different model structures and different sets of model parameters with regards to its ability of mitigating N2O emissions for future applications in real wastewater treatment plants. It is concluded that the control strategy...... is useful for those plants having AOB denitrification as the main N2O producing process. However, in treatment plants having incomplete NH2OH oxidation as the main N2O producing pathway, a cascade controller configuration adapting the oxygen supply to respect only the effluent ammonium concentration limits...

  5. Human ECG Changes During Prolonged Hyperbaric Exposures Breathing N2-O2 Mixtures

    National Research Council Canada - National Science Library

    Wilson, James M; Kligfield, Paul D; Adams, George M; Harvey, Claude; Schaefer, Karl E

    1976-01-01

    In an effort to determine whether hyperbaric exposures while breathing N2-O2 mixtures have an effect on cardiac depolarization and repolarization, electrocardiograms of 10 divers participating in four...

  6. MLS/Aura Level 2 Nitrous Oxide (N2O) Mixing Ratio V004

    Data.gov (United States)

    National Aeronautics and Space Administration — ML2N2O is the EOS Aura Microwave Limb Sounder (MLS) standard product for nitrous oxide derived from radiances measured primarily by the 640 GHz radiometer (Band 12)...

  7. HIRDLS/Aura Level 3 Dinitrogen Pentoxide (N2O5) Zonal Fourier Coefficients V007

    Data.gov (United States)

    National Aeronautics and Space Administration — The "HIRDLS/Aura Level 3 Dinitrogen Pentoxide (N2O5) Zonal Fourier Coefficients" version 7 data product (H3ZFCN2O) contains the entire mission (~3 years) of HIRDLS...

  8. The role of cellular catalase on the radiosensitization of bacterial vegetative cells by N2O

    International Nuclear Information System (INIS)

    Watanabe, H.; Takehisa, M.

    1983-01-01

    The radiosensitizing effect of N 2 O on eight strains of bacteria was measured in dilute suspensions. The dose-modifying factors (DMF) of N 2 O on M. radiodurans R 1 , P. radiora O-1, M. lysodeikticus and B. pumilus E601 (vegetative cells) were 3.4, 2.9, 2.4 and 1.7, respectively. But P. radiora RP-C, P. fluorescens B3-1, E. coli B/r and E. coli K-12 were hardly sensitized by N 2 O. From measurements of catalase activity of each bacterium, it was found that the DMF increases with increased catalase activity, suggesting that cellular catalase promotes the sensitizing action of N 2 O. (author)

  9. European-scale modelling of groundwater denitrification and associated N2O production

    KAUST Repository

    Keuskamp, J.A.

    2012-06-01

    This paper presents a spatially explicit model for simulating the fate of nitrogen (N) in soil and groundwater and nitrous oxide (N 2O) production in groundwater with a 1 km resolution at the European scale. The results show large heterogeneity of nitrate outflow from groundwater to surface water and production of N 2O. This heterogeneity is the result of variability in agricultural and hydrological systems. Large parts of Europe have no groundwater aquifers and short travel times from soil to surface water. In these regions no groundwater denitrification and N 2O production is expected. Predicted N leaching (16% of the N inputs) and N 2O emissions (0.014% of N leaching) are much less than the IPCC default leaching rate and combined emission factor for groundwater and riparian zones, respectively. © 2012 Elsevier Ltd. All rights reserved.

  10. Towards an optimal experimental design for N2O model calibration during biological nitrogen removal

    DEFF Research Database (Denmark)

    Domingo Felez, Carlos; Valverde Pérez, Borja; Plósz, Benedek G.

    substrates. Improving experimental designs for model calibration reduces prediction uncertainties. Moreover, the individual analysis of autotrophic and heterotrophic contribution to the total NO and N2O pool was assessed for already proposed model structures under different experimental scenarios...

  11. N2 O A greenhouse gas released from the combustion of coals in fluidized beds

    International Nuclear Information System (INIS)

    Boavida, D.; Lobo, L. S.; Gulyurtlu, I.; Cabrita, I.

    1996-01-01

    This paper discusses the results of the experimental work investigating the formation of N-2 O and NO during fluidized bed combustion of coals, and of chars and volatiles produced from the pyrolysis of these coals. Ammonia (N H 3 ) and hydrogen cyanide (HCN) are shown to play important roles as gas phase precursors of both NO and N 2 O. The conversion of fuel-N through N H 3 and HCN to N 2 O and NO was studied using a fluidized bed combustor in the temperature range between 973 K and 1273 K, for two different coals. The results suggest that the principal contribution to N 2 O emission Originated from volatile-N, however, char-N could also have an important role, depending upon the temperature. 1 fig., 8 tabs

  12. MLS/Aura L2 Nitrous Oxide (N2O) Mixing Ratio V002

    Data.gov (United States)

    National Aeronautics and Space Administration — ML2N2O is the EOS Aura Microwave Limb Sounder (MLS) standard product for nitrous oxide derived from radiances measured primarily by the 640 GHz radiometer (Band 12)...

  13. Soil biochar amendment shapes the composition of N2O-reducing microbial communities

    International Nuclear Information System (INIS)

    Harter, Johannes; Weigold, Pascal; El-Hadidi, Mohamed; Huson, Daniel H.; Kappler, Andreas; Behrens, Sebastian

    2016-01-01

    Soil biochar amendment has been described as a promising tool to improve soil quality, sequester carbon, and mitigate nitrous oxide (N 2 O) emissions. N 2 O is a potent greenhouse gas. The main sources of N 2 O in soils are microbially-mediated nitrogen transformation processes such as nitrification and denitrification. While previous studies have focused on the link between N 2 O emission mitigation and the abundance and activity of N 2 O-reducing microorganisms in biochar-amended soils, the impact of biochar on the taxonomic composition of the nosZ gene carrying soil microbial community has not been subject of systematic study to date. We used 454 pyrosequencing in order to study the microbial diversity in biochar-amended and biochar-free soil microcosms. We sequenced bacterial 16S rRNA gene amplicons as well as fragments of common (typical) nosZ genes and the recently described ‘atypical’ nosZ genes. The aim was to describe biochar-induced shifts in general bacterial community diversity and taxonomic variations among the nosZ gene containing N 2 O-reducing microbial communities. While soil biochar amendment significantly altered the 16S rRNA gene-based community composition and structure, it also led to the development of distinct functional traits capable of N 2 O reduction containing typical and atypical nosZ genes related to nosZ genes found in Pseudomonas stutzeri and Pedobacter saltans, respectively. Our results showed that biochar amendment can affect the relative abundance and taxonomic composition of N 2 O-reducing functional microbial traits in soil. Thus these findings broaden our knowledge on the impact of biochar on soil microbial community composition and nitrogen cycling. - Highlights: • Biochar promoted anaerobic, alkalinity-adapted, and polymer-degrading microbial taxa. • Biochar fostered the development of distinct N 2 O-reducing microbial taxa. • Taxonomic shifts among N 2 O-reducing microbes might explain lower N 2 O emissions.

  14. Effects of crop management, soil type, and climate on N2O emissions from Austrian Soils

    Science.gov (United States)

    Zechmeister-Boltenstern, Sophie; Sigmund, Elisabeth; Kasper, Martina; Kitzler, Barbara; Haas, Edwin; Wandl, Michael; Strauss, Peter; Poetzelsberger, Elisabeth; Dersch, Georg; Winiwarter, Wilfried; Amon, Barbara

    2015-04-01

    Within the project FarmClim ("Farming for a better climate") we assessed recent N2O emissions from two selected regions in Austria. Our aim was to deepen the understanding of Austrian N2O fluxes regarding region specific properties. Currently, N2O emissions are estimated with the IPCC default emission factor which only considers the amount of N-input as an influencing factor for N2O emissions. We evaluated the IPCC default emission factor for its validity under spatially distinct environmental conditions. For this two regions for modeling with LandscapeDNDC have been identified in this project. The benefit of using LandscapeDNDC is the detailed illustration of microbial processes in the soil. Required input data to run the model included daily climate data, vegetation properties, soil characteristics and land management. The analysis of present agricultural practices was basis for assessing the hot spots and hot moments of nitrogen emissions on a regional scale. During our work with LandscapeDNDC we were able to adapt specific model algorithms to Austrian agricultural conditions. The model revealed a strong dependency of N2O emissions on soil type. We could estimate how strongly soil texture affects N2O emissions. Based on detailed soil maps with high spatial resolution we calculated region specific contribution to N2O emissions. Accordingly we differentiated regions with deviating gas fluxes compared to the predictions by the IPCC inventory methodology. Taking region specific management practices into account (tillage, irrigation, residuals) calculation of crop rotation (fallow, catch crop, winter wheat, barley, winter barley, sugar beet, corn, potato, onion and rapeseed) resulted in N2O emissions differing by a factor of 30 depending on preceding crop and climate. A maximum of 2% of N fertilizer input was emitted as N2O. Residual N in the soil was a major factor stimulating N2O emissions. Interannual variability was affected by varying N-deposition even in case

  15. Combining two complementary micrometeorological methods to measure CH4 and N2O fluxes over pasture

    Science.gov (United States)

    Laubach, Johannes; Barthel, Matti; Fraser, Anitra; Hunt, John E.; Griffith, David W. T.

    2016-03-01

    New Zealand's largest industrial sector is pastoral agriculture, giving rise to a large fraction of the country's emissions of methane (CH4) and nitrous oxide (N2O). We designed a system to continuously measure CH4 and N2O fluxes at the field scale on two adjacent pastures that differed with respect to management. At the core of this system was a closed-cell Fourier transform infrared (FTIR) spectrometer, which measured the mole fractions of CH4, N2O and carbon dioxide (CO2) at two heights at each site. In parallel, CO2 fluxes were measured using eddy-covariance instrumentation. We applied two different micrometeorological ratio methods to infer the CH4 and N2O fluxes from their respective mole fractions and the CO2 fluxes. The first is a variant of the flux-gradient method, where it is assumed that the turbulent diffusivities of CH4 and N2O equal that of CO2. This method was reliable when the CO2 mole-fraction difference between heights was at least 4 times greater than the FTIR's resolution of differences. For the second method, the temporal increases of mole fractions in the stable nocturnal boundary layer, which are correlated for concurrently emitted gases, are used to infer the unknown fluxes of CH4 and N2O from the known flux of CO2. This method was sensitive to "contamination" from trace gas sources other than the pasture of interest and therefore required careful filtering. With both methods combined, estimates of mean daily CH4 and N2O fluxes were obtained for 56 % of days at one site and 73 % at the other. Both methods indicated both sites as net sources of CH4 and N2O. Mean emission rates for 1 year at the unfertilised, winter-grazed site were 8.9 (±0.79) nmol CH4 m-2 s-1 and 0.38 (±0.018) nmol N2O m-2 s-1. During the same year, mean emission rates at the irrigated, fertilised and rotationally grazed site were 8.9 (±0.79) nmol CH4 m-2 s-1 and 0.58 (±0.020) nmol N2O m-2 s-1. At this site, the N2O emissions amounted to 1.21 (±0.15) % of the nitrogen

  16. Development of a High Precision and Stability Ambient N2O and CO Analyzer

    Science.gov (United States)

    Zhou, Jingang; Hoffnagle, John; Tan, Sze; Dong, Feng; Fleck, Derek; Yiu, John; Huang, Kuan; Leggett, Graham; He, Yonggang

    2016-04-01

    With a global warming potential of nearly 300, N2O is a critically important greenhouse gas, contributing about 5 % of the US total GHG emissions. Agriculture soil management practices are the dominant source of anthropogenic N2O emissions, contributing nearly 75 % of US N2O emissions. In urban areas, vehicle tailpipe emissions and waste water treatment plants are significant sources of N2O. We report here a new mid-infrared laser-based cavity ring-down spectrometer (Picarro G5310) that was recently developed to simultaneously measure sub-ppb ambient concentrations of two key greenhouse gas species, N2O and CO, while measuring H2O as well. It combines a quantum cascade laser with a proprietary 3-mirror optical cavity. The ambient N2O and CO measurement precisions are 0.1ppb (10sec), 0.014ppb (600sec), and 0.006ppb (3000sec); and the measurements could even be averaged down over 3 hours, giving measurement precisions of 0.003ppb. The measurable N2O and CO ranges have been tested up to 2.5ppm. With the high precision and unparalleled stability, G5310 is believed a promising tool for long-term monitoring in atmospheric sciences. The new optical analyzer was set up to monitor N2O and CO (G5310), along with CO2 and CH4(G4301), in ambient air obtained from a 10 meter tower in Santa Clara, California. Evidence of contributions from traffic and a nearby sewage treatment facility were expected in the measurement data.

  17. Rotational excitation of linear triatomic molecules: Ar, Kr + N2O, CO2

    International Nuclear Information System (INIS)

    Farrar, J.M.; Parson, J.M.; Lee, Y.T.

    1974-01-01

    Rotational excitation of N 2 O and CO 2 in collisions with Ar and Kr has been studied by crossing two supersonic molecular beams and detecting scattered products with a mass spectrometer. Measurement of the time of flight spectrum of the products as a function of laboratory scattering angle theta indicates that the inelasticity is concentrated in the forward direction in the center of mass system. Difference between CO 2 and N 2 O are discussed briefly

  18. Tillage effects on N2O emission from soils under corn and soybeans in eastern Canada

    International Nuclear Information System (INIS)

    Gregorich, E.G.; St-Georges, P.; McKim, U.F.; Chan, C.; Rochette, P.

    2008-01-01

    New research has suggested that no-till agricultural practices will result in higher levels of nitrous oxide (N 2 O) emissions due to increased levels of denitrification. This study was evaluated and compared N 2 O emissions from tilled and no-till soils. Data used in the study were comprised of more than 1500 flux measurements of N 2 O taken between April and October over a period of 3 years at a site in Ottawa, Ontario. Soybean and corn crop rotations were used. Treatment effects of tillage, crop, and time of season on N 2 O fluxes were assessed using analysis of variance (ANOVA) methods. The study evaluated the responses of tillage during periods when soil temperatures were above 0 degrees C. Results of the studies demonstrated that fertilization management practices contributed to the higher N 2 O emissions observed in soils planted with corn when compared with soils planted with soybeans. Biological nitrogen (N) fixation in soybeans did not contribute to annual N 2 O emissions, and the effects of tillage on N 2 O emissions varied from year to year. The tilled soils typically had better aeration, higher temperatures, and lower water content than no-till soils. N 2 O emissions from no-till soils were lower than rates observed in tilled soils in 2 of the 3 years studied. Higher emissions observed in no-till soils were attributed to timing and the method of fertilizer placement. It was concluded that further studies are needed to develop methods of improving N use efficiency within tillage systems. 30 refs., 5 tabs., 2 figs

  19. Synthesis and Characterization of Benzo-15-Crown-5 Ethers with Appended N2O Schiff Bases

    Directory of Open Access Journals (Sweden)

    Baltazar de Castro

    2003-12-01

    Full Text Available New derivatives of benzo-15-crown-5 with flexible appended N2O unsymmetrical Schiff bases were prepared by a two step procedure which involves: (i preparation of N2O Schiff bases by condensation of hydrazine with salicylaldehyde, 3-methoxysalicylaldehyde or 2-hydroxy-1-naphtaldehyde and (ii reaction of the resulting NH2 functionalized compounds with 4’-formyl-benzo-15-crown-5.

  20. Fungi regulate response of N2O production to warming and grazing in a Tibetan grassland

    Science.gov (United States)

    Zhong, Lei; Wang, Shiping; Xu, Xingliang; Wang, Yanfen; Rui, Yichao; Zhou, Xiaoqi; Shen, Qinhua; Wang, Jinzhi; Jiang, Lili; Luo, Caiyun; Gu, Tianbao; Ma, Wenchao; Chen, Guanyi

    2018-03-01

    Lack of understanding of the effects of warming and winter grazing on soil fungal contribution to nitrous oxide (N2O) production has limited our ability to predict N2O fluxes under changes in climate and land use management, because soil fungi play an important role in driving terrestrial N cycling. Here, we examined the effects of 10 years' warming and winter grazing on soil N2O emissions potential in an alpine meadow. Our results showed that soil bacteria and fungi contributed 46 % and 54 % to nitrification, and 37 % and 63 % to denitrification, respectively. Neither warming nor winter grazing affected the activity of enzymes responsible for overall nitrification and denitrification. However, warming significantly increased the enzyme activity of bacterial nitrification and denitrification to 53 % and 55 %, respectively. Warming significantly decreased enzyme activity of fungal nitrification and denitrification to 47 % and 45 %, respectively, while winter grazing had no such effect. We conclude that soil fungi could be the main source for N2O production potential in the Tibetan alpine grasslands. Warming and winter grazing may not affect the potential for soil N2O production potential, but climate warming can alter biotic pathways responsible for N2O production. These findings indicate that characterizing how fungal nitrification/denitrification contributes to N2O production, as well as how it responds to environmental and land use changes, can advance our understanding of N cycling. Therefore, our results provide some new insights about ecological controls on N2O production and lead to refine greenhouse gas flux models.

  1. Spatial prediction of N2O emissions in pasture: a Bayesian model averaging analysis.

    Directory of Open Access Journals (Sweden)

    Xiaodong Huang

    Full Text Available Nitrous oxide (N2O is one of the greenhouse gases that can contribute to global warming. Spatial variability of N2O can lead to large uncertainties in prediction. However, previous studies have often ignored the spatial dependency to quantify the N2O - environmental factors relationships. Few researches have examined the impacts of various spatial correlation structures (e.g. independence, distance-based and neighbourhood based on spatial prediction of N2O emissions. This study aimed to assess the impact of three spatial correlation structures on spatial predictions and calibrate the spatial prediction using Bayesian model averaging (BMA based on replicated, irregular point-referenced data. The data were measured in 17 chambers randomly placed across a 271 m(2 field between October 2007 and September 2008 in the southeast of Australia. We used a Bayesian geostatistical model and a Bayesian spatial conditional autoregressive (CAR model to investigate and accommodate spatial dependency, and to estimate the effects of environmental variables on N2O emissions across the study site. We compared these with a Bayesian regression model with independent errors. The three approaches resulted in different derived maps of spatial prediction of N2O emissions. We found that incorporating spatial dependency in the model not only substantially improved predictions of N2O emission from soil, but also better quantified uncertainties of soil parameters in the study. The hybrid model structure obtained by BMA improved the accuracy of spatial prediction of N2O emissions across this study region.

  2. N2O + CO reaction over single Ga or Ge atom embedded graphene: A DFT study

    Science.gov (United States)

    Esrafili, Mehdi D.; Vessally, Esmail

    2018-01-01

    The possibility of using a single Ga or Ge atom embedded graphene as an efficient catalyst for the reduction of N2O molecule by CO is examined. We perform density functional theory calculations to calculate adsorption energies as well as analysis of the structural and electronic properties of different species involved in the N2O + CO reaction. The large activation energy for the diffusion of the single Ga or Ge atom on the C vacancy site of graphene shows the high stability of both Ga- and Ge-embedded graphene sheets in the N2O reduction. The activation energy needed for the decomposition of N2O is calculated to be 18.4 and 14.1 kcal/mol over Ga- and Ge-embedded graphene, respectively. The results indicate that the Ge-embedded graphene may serve as an effective catalyst for the N2O reduction. Moreover, the activation energy for the disproportionation of N2O molecules that generates N2 and O2 is relatively high; so, the generation of these side products may be hindered by decreasing the temperature.

  3. Microbial CH4 and N2O consumption in acidic wetlands

    Directory of Open Access Journals (Sweden)

    Steffen eKolb

    2012-03-01

    Full Text Available Acidic wetlands are global sources of the atmospheric greenhouse gases methane (CH4, and nitrous oxide (N2O. Consumption of both atmospheric gases has been observed in various acidic wetlands, but information on the microbial mechanisms underlying these phenomena is scarce. A substantial amount of CH4 is consumed in sub soil by aerobic methanotrophs at anoxic–oxic interfaces (e.g., tissues of Sphagnum mosses, rhizosphere of vascular plant roots. Methylocystis-related species are likely candidates that are involved in the consumption of atmospheric CH4 in acidic wetlands. Oxygen availability regulates the activity of methanotrophs of acidic wetlands. Other parameters impacting on the methanotroph-mediated CH4 consumption have not been systematically evaluated. N2O is produced and consumed by microbial denitrification, thus rendering acidic wetlands as temporary sources or sinks for N2O. Denitrifier communities in such ecosystems are diverse, and largely uncultured and/or new, and environmental factors that control their consumption activity are unresolved. Analyses of the composition of N2O reductase genes in acidic wetlands suggest that acid-tolerant Proteobacteria have the potential to mediate N2O consumption in such soils. Thus, the fragmented current state of knowledge raises open questions concerning methanotrophs and dentrifiers that consume atmospheric CH4 and N2O in acidic wetlands.

  4. Modeling electron competition among nitrogen oxides reduction and N2 O accumulation in hydrogenotrophic denitrification.

    Science.gov (United States)

    Liu, Yiwen; Ngo, Huu H; Guo, Wenshan; Peng, Lai; Chen, Xueming; Wang, Dongbo; Pan, Yuting; Ni, Bing-Jie

    2018-04-01

    Hydrogenotrophic denitrification is a novel and sustainable process for nitrogen removal, which utilizes hydrogen as electron donor, and carbon dioxide as carbon source. Recent studies have shown that nitrous oxide (N 2 O), a highly undesirable intermediate and potent greenhouse gas, can accumulate during this process. In this work, a new mathematical model is developed to describe nitrogen oxides dynamics, especially N 2 O, during hydrogenotrophic denitrification for the first time. The model describes electron competition among the four steps of hydrogenotrophic denitrification through decoupling hydrogen oxidation and nitrogen reduction processes using electron carriers, in contrast to the existing models that couple these two processes and also do not consider N 2 O accumulation. The developed model satisfactorily describes experimental data on nitrogen oxides dynamics obtained from two independent hydrogenotrophic denitrifying cultures under various hydrogen and nitrogen oxides supplying conditions, suggesting the validity and applicability of the model. The results indicated that N 2 O accumulation would not be intensified under hydrogen limiting conditions, due to the higher electron competition capacity of N 2 O reduction in comparison to nitrate and nitrite reduction during hydrogenotrophic denitrification. The model is expected to enhance our understanding of the process during hydrogenotrophic denitrification and the ability to predict N 2 O accumulation. © 2017 Wiley Periodicals, Inc.

  5. Contribution of nitrification and denitrification to N2O emissions from urine patches

    DEFF Research Database (Denmark)

    Carter, Mette Sustmann

    2007-01-01

    Urine deposition by grazing livestock causes an immediate increase in nitrous oxide (N(2)O) emissions, but the responsible mechanisms are not well understood. A nitrogen-15 ((15)N) labelling study was conducted in an organic grass-clover sward to examine the initial effect of urine on the rates...... nitrification rates were measured in the field, whereas the denitrification rates were measured in soil cores in the laboratory. Compared with the water control, urine application increased the N(2)O emission from 3.9 to 42.3 mu g N(2)O-N m(-2) h(-1), whereas application of ammonium increased the emission from...... 0.9 to 6.1 mu g N(2)ON m(-2) h(-1). In the urine-affected soil, nitrification and denitrification contributed equally to the N(2)O emission, and the increased N(2)O loss resulted from a combination of higher rates and higher N(2)O loss ratios of the processes. In the present study, an enhanced...

  6. Study of N2O Formation over Rh- and Pt-Based LNT Catalysts

    Directory of Open Access Journals (Sweden)

    Lukasz Kubiak

    2016-03-01

    Full Text Available In this paper, mechanistic aspects involved in the formation of N2O over Pt-BaO/Al2O3 and Rh-BaO/Al2O3 model NOx Storage-Reduction (NSR catalysts are discussed. The reactivity of both gas-phase NO and stored nitrates was investigated by using H2 and NH3 as reductants. It was found that N2O formation involves the presence of gas-phase NO, since no N2O is observed upon the reduction of nitrates stored over both Pt- and Rh-BaO/Al2O3 catalyst samples. In particular, N2O formation involves the coupling of undissociated NO molecules with N-adspecies formed upon NO dissociation onto reduced Platinum-Group-Metal (PGM sites. Accordingly, N2O formation is observed at low temperatures, when PGM sites start to be reduced, and disappears at high temperatures where PGM sites are fully reduced and complete NO dissociation takes place. Besides, N2O formation is observed at lower temperatures with H2 than with NH3 in view of the higher reactivity of hydrogen in the reduction of the PGM sites and onto Pt-containing catalyst due to the higher reducibility of Pt vs. Rh.

  7. Biochar Mediated Mechanisms for Reducing N2O Emissions: An Overview

    Science.gov (United States)

    Ippolito, Jim; Kammann, Claudia; Schirrmann, Michael; Wrage-Mönnig, Nicole; Estavillo, Txema; Fuertes, Teresa; Cayuela, Mariluz; Borchard, Nils; Novak, Jeff; Spokas, Kurt; Sigua, Gilbert

    2017-04-01

    Continuing land-use change (e.g., greater inorganic and organic N fertilizer use) due to increasing population growth has led to significant increases in global N2O emissions. N2O has a high global warming potential; thus, a clear need exists to lessen further emissions. Biochar, a pyrolysis by-product, holds promise as a material that can influence soil and manure N transformations and drastically reduce N2O emissions. Biochar has been shown to: 1) entrap and thus decrease NO3-N concentrations; 2) sorb and thus decrease NH4-N concentrations; 3) alter microbial community composition; 4) be a source of electrons and thus alter redox conditions; 5) potentially react with N2O; and 6) locally increase soil pH, all of which can lead to reduced N2O emissions. The purpose of this presentation is to provide overarching mechanisms behind these six points in terms of how biochar reduces N2O emissions.

  8. Experimental assessment of N2O background fluxes in grassland systems

    International Nuclear Information System (INIS)

    Neftel, Albrecht; Flechard, Chris; Ammann, Christof; Conen, Franz; Emmenegger, Lukas; Zeyer, Kerstin

    2007-01-01

    In the absence of, or between, fertilization events in agricultural systems, soils are generally assumed to emit N 2 O at a small rate, often described as the 'background' flux. In contrast, net uptake of N 2 O by soil has been observed in many field studies, but has not gained much attention. Observations of net uptake of N 2 O form a large fraction (about half) of all individual flux measurements in a long-term time series at our temperate fertilized grassland site. Individual uptake fluxes from chamber measurements are often not statistically significant but mean values integrated over longer time periods from days to weeks do show a clear uptake. An analysis of semi-continuous chamber flux data in conjunction with continuous measurements of the N 2 O concentration in the soil profile and eddy covariance measurements suggests that gross production and gross consumption of N 2 O are of the same order, and as consequence only a minor fraction of N 2 O molecules produced in the soil reaches the atmosphere

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

    Science.gov (United States)

    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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. N2O emissions from an apple orchard in the coastal area of Bohai Bay, China.

    Science.gov (United States)

    Xie, Baohua; Yu, Junbao; Zheng, Xunhua; Qu, Fanzhu; Xu, Yu; Lin, Haitao

    2014-01-01

    Using static chambers and gas chromatography, nitrous oxide (N2O) fluxes from an apple orchard soil in the Bohai Bay region of China were measured from February 2010 to February 2011. In this study, two nitrogen (N) fertilizer treatments were designed--without (CK) or with (SN) synthetic N fertilizers (800 kg N ha(-1)). The annual cumulative N2O emissions from CK and SN were 34.6 ± 3.0 (mean ± standard error) and 44.3 ± 6.0 kg N2O-N ha(-1), respectively. Such high emissions resulted from the intensive N fertilization in the experimental and previous years. The direct emission factor (EFd) of N2O induced by the applied synthetic N fertilizers was 1.2%. The EFd is within the range of previous studies carried out in other croplands, which suggests that it is reasonable to estimate regional N2O emissions from apple orchards using the EFd obtained in other croplands. In addition, significant positive correlations existed between N2O fluxes and soil temperatures or soil dissolved organic carbon contents.

  11. Direct impacts of biochar on N2O production during denitrification by a soil microbial community

    Science.gov (United States)

    Mishra, Akanksha; Harter, Johannes; Hagemann, Nikolas; Kappler, Andreas

    2017-04-01

    Biochar, i.e. biomass heated under O2 limitation to 350-1000°C (pyrolysis), is suggested as a beneficial soil amendment to mitigate climate change and to maintain and restore the fertility of agro-ecosystems. Its stability enables long-term carbon sequestration and biochar effectively reduces soil-borne N2O emissions. Biochar's ability to reduce N2O emissions is well recognized through field and laboratory experiments as well as meta-analyses. However, the underlying mechanisms remain widely debated. Microbial nitrogen transformations, especially denitrification, the stepwise reduction of nitrate/nitrite via NO and N2O to N2, are considered to be a major source of N2O emissions. Soil microcosm experiments showed lower N2O emissions in the presence of biochar often correlate with a higher abundance and/or activity of N2O reducing bacteria in the presence of biochar. However, it is still unknown whether these shifts in the microbial community and/or activity is cause or effect of reduced N2O production. Biochar has the potential to change the physico-chemical environment towards conditions that favor complete denitrification, i.e. decrease the N2O/(N2O+N2) product ratio. Specifically, biochar can increase soil pH, reduce the availability of nitrate and increase the entrapment of gases, including N2O. These effects are known to decrease the N2O/(N2O+N2) ratio. In addition to the observed effects in the physio-chemical environment, we hypothesized that biochar has a direct impact on the soil microbial community. For instance, it has been shown to provide a suitable habitat to microorganisms, or facilitate electron transfer between microbe and substrates by acting as an electron shuttle or as a temporary acceptor/donor of electrons. To test this hypothesis, our experiment consisted of a microbial community extracted from soil and cultivated under anoxic conditions. It was introduced as an inoculum into three different treatments: biochar, quartz (control with a solid

  12. Investigation of dissolved N2O production processes during wastewater treatment system in Ulaanbaatar

    Directory of Open Access Journals (Sweden)

    Tumendelger A

    2017-02-01

    Full Text Available Nitrous oxide (N2O is an increasing greenhouse gas in the troposphere and a potential destroyer of stratospheric ozone layer. Wastewater treatment plant (WWTP is one of the anthropogenic N2O sources because inorganic and organic nitrogen compounds are converted to nitrate (NO3-, in the case of standard system or N2 (in the case of advanced system by bacterial nitrification and denitrifcation processes in WWTP. These major processes can be distinguished by isotopocule analysis. In order to reveal production mechanisms of N2O in a standard wastewater treatment, we made water sampling at the central WWTP in Ulaanbaatar. The water samples collected from seven stations including biological reaction tanks were measured for concentration and isotopocule ratios of dissolved N2O and other inorganic nitrogen. Dissolved N2O concentration was extremely higher than that expected under atmospheric equilibrium (about 9 nmol/l at all stations, indicating that this system is a potential source of N2O. It showed a gradual increase with the progress of biological reaction and the highest concentration (335.7 nmol/l was observed at station N5-4 of the aeration tank when the DO was 5.7 mg/l. Nitrification by nitrifying bacteria could actively occur by the concentration of NH4+ decreased whereas NO2- and NO3- showed a temporal and monotonic increase, respectively, under high DO concentration. Although the reported values of site preference (SP of N2O, the difference in 15N/14N ratio between central (α and terminal (β nitrogen, produced via NO2- reduction (SP(ND, including both nitrifier and denitrifier denitrification, and NH2OH oxidation (SP(HO ranged from -10.7‰ to 0‰ and 31.4‰ to 36.3‰, respectively, the observed SP at aeration tank was close to SP(ND rather than SP(HO. It was ranged from 0.4‰ to 13.3‰ when N2O concentration was high, implying that the NO2- reduction made a greater contribution to N2O production. Slightly elevated SP (13.3‰ only at

  13. Background CH4 and N2O fluxes in low-input short rotation coppice

    Science.gov (United States)

    Görres, Carolyn-Monika; Zenone, Terenzio; Ceulemans, Reinhart

    2016-04-01

    Extensively managed short rotation coppice systems are characterized by low fluxes of CH4 and N2O. However due to the large global warming potential of these trace gases (GWP100: CH4: 34, N2O: 298), such background fluxes can still significantly contribute to offsetting the CO2 uptake of short rotation coppice systems. Recent technological advances in fast-response CH4 and N2O analysers have improved our capability to capture these background fluxes, but their quantification still remains a challenge. As an example, we present here CH4 and N2O fluxes from a short-rotation bioenergy plantation in Belgium. Poplars have been planted in a double-row system on a loamy sand in 2010 and coppiced in the beginning of 2012 and 2014 (two-year rotation system). In 2013 (June - November) and 2014 (April - August), the plantation's CH4 and N2O fluxes were measured in parallel with an eddy covariance tower (EC) and an automated chamber system (AC). The EC had a detection limit of 13.68 and 0.76 μmol m-2 h-1 for CH4 and N2O, respectively. The median detection limit of the AC was 0.38 and 0.08 μmol m-2 h-1 for CH4 and N2O, respectively. The EC picked up a few high CH4 emission events with daily averages >100 μmol m-2 h-1, but a large proportion of the measured fluxes were within the EC's detection limit. The same was true for the EC-derived N2O fluxes where the daily average flux was often close to the detection limit. Sporadically, some negative (uptake) fluxes of N2O were observed. On the basis of the EC data, no clear link was found between CH4 and N2O fluxes and environmental variables. The problem with fluxes within the EC detection limit is that a significant amount of the values can show the opposite sign, thus "mirroring" the true flux. Subsequently, environmental controls of background trace gas fluxes might be disguised in the analysis. As a next step, it will be tested if potential environmental drivers of background CH4 and N2O fluxes at the plantation can be

  14. Precise soil management as a tool to reduce CH4 and N2O emissions from agricultural soils

    NARCIS (Netherlands)

    Mosquera Losada, J.; Hol, J.M.G.; Rappoldt, C.; Dolfing, J.

    2007-01-01

    Soil compaction stimulates the emission of nitrous oxide (N2O) and methane (CH4) from agricultural soils. N2O and CH4 are potent greenhouse gases, with a global warming potential respectively 296 times and 23 times greater than CO2.. Agricultural soils are an important source of N2O. Hence there is

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

    Science.gov (United States)

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

  16. Yield-scaled N2O emissions in a winter wheat - summer corn double-cropping system

    NARCIS (Netherlands)

    Qin, S.; Wang, Y.; Hu, C.; Oenema, O.; Li, X.; Zhang, Y.; Dong, W.

    2012-01-01

    Emissions of nitrous oxide (N2O) from agricultural soils contribute to global warming and stratospheric ozone depletion. Applications of fertilizer nitrogen (N) increase N2O emission, but also increase agricultural production. Here, we report on the responses of crop yield, N2O emission and

  17. MLS/Aura Near-Real-Time L2 Nitrous Oxide (N2O) Mixing Ratio V003

    Data.gov (United States)

    National Aeronautics and Space Administration — ML2N2O_NRT is the EOS Aura Microwave Limb Sounder (MLS) Near-Real-Time (NRT) product for nitrous oxide (N2O). This product contains daily N2O profiles taken from the...

  18. Utilizing the Gate-Opening Mechanism in ZIF-7 for Adsorption Discrimination between N2O and CO2

    NARCIS (Netherlands)

    Chen, D.L.; Wang, N.; Wang, F.F.; Xie, J.; Zhong, Y.; Zhu, W.; Johnson, J.K.; Krishna, R.

    2014-01-01

    N2O is a greenhouse gas with tremendous global warming potential, and more importantly it also causes ozone depletion; thus, the separation of N2O from industrial processes has gained significant attention. We have demonstrated that N2O can be selectively separated from CO2 using the zeolite

  19. Near-Continuous Isotopic Characterization of Soil N2O Fluxes from Maize Production

    Science.gov (United States)

    Anex, R. P.; Francis Clar, J.

    2015-12-01

    Isotopomer ratios of N2O and especially intramolecular 15N site preference (SP) have been proposed as indicators of the sources of N2O and for providing insight into the contributions of different microbial processes. Current knowledge, however, is mainly based on pure culture studies and laboratory flask studies using mass spectrometric analysis. Recent development of laser spectroscopic methods has made possible high-precision, in situ measurements. We present results from a maize production field in Columbia County, Wisconsin, USA. Data were collected from the fertilized maize phase of a maize-soybean rotation. N2O mole fractions and isotopic composition were determined using an automatic gas flux measurement system comprising a set of custom-designed automatic chambers, circulating gas paths and an OA-ICOS N2O Isotope Analyzer (Los Gatos Research, Inc., Model 914-0027). The instrument system allows for up to 15 user programmable soil gas chambers. Wide dynamic range and parts-per-billion precision of OA-ICOS laser absorption instrument allows for extremely rapid estimation of N2O fluxes. Current operational settings provide measurements of N2O and its isotopes every 20 seconds with a precision of 0.1 ± 0.050 PPB. Comparison of measurements from four chambers (two between row and two in-row) show very different aggregate N2O flux, but SP values suggest similar sources from nitrifier denitrification and incomplete bacterial denitrification. SP values reported are being measured throughout the current growing season. To date, the majority of values are consistent with an origin from bacterial denitrification and coincide with periods of high water filled pore space.

  20. Sunflower N2O emissions under two different water regimes in Mediterranean climate

    Science.gov (United States)

    Monaco, Eugenia; Vitale, Luca; Di Tommasi, Paul; Tedeschi, Anna; Tosca, Maurizio; Magliulo, Vincenzo

    2017-04-01

    Human activities are altering the atmospheric greenhouse gases (GHGs) concentration with negative effects on global climate and environment. Cropland represents about 12 % of earth's surface and largely contribute to GHGs production, in particular N2O, due to a massive use of nitrogen fertilization. In particular, agriculture and intensive livestock farming may significantly affect biogeochemical cycles included nitrogen cycle. However, it is often difficult to predict the total amount of fluxes caused by agricultural management, which impact on both the whole agro-ecosystem. The objective of the experiment was to evaluate soil N2O fluxes under two different irrigation managements. The experimental trial was conducted in a farm in surrounding of Naples, southern Italy. The crop monitored was sunflower for biomass uses. Two irrigation levels were performed: returning 100% (optimal irrigation) and 50% (deficit irrigation) of soil field capacity for the layer 0.0-0.50 m. 314 Kg ha-1 of urea fertilizer was supplied in two times: at sowing and 40 days later. Before sowing, six autochambers were inserted 3 cm into the soil and connected to a gas chromatograph and a scanning apparatus. A program for chambers' management was implemented to monitor soil N2O fluxes measured different times of the day. Biometric parameters such as LAI, root depth, above- and below-ground biomass were monitored during the experiment. Results shows that soil N2O fluxes were affected by irrigation regime; in particular, the deficit irrigation determined lower N2O fluxes compared to optimal irrigation but the total biomass production and yield were comparable between the two water regimes. So low input farm management could be take in account to reduce the total N2O emission and maintain at the same time high productivity level in terms of biomass and yield. Keywords: N2O fluxes, Irrigation schedule, sunflower

  1. Decaying cyanobacteria decrease N2O emissions related to diversity of intestinal denitrifiers of Chironomus plumosus

    Directory of Open Access Journals (Sweden)

    Xu Sun

    2014-10-01

    Full Text Available Nitrous oxide (N2O emission of fresh invertebrates has too long been neglected in eutrophic lakes, although the sediments these animals inhabit are presumably hot spots of N2O emission. Thus, the experiment in this research was designed to gain insight into the influence of cyanobacterial degradation on the N2O emission by fresh water invertebrates (Chironomus plumosus. The presence of decaying cyanobacteria in Lake Taihu decreased the N2O emission rate of Chironomus plumosus larvae from the larvae body by almost 400% for the larvae as a whole. The N2O emission rate decreased by 350% based on readings from studies of their gut, which was mostly due to stimulation of intestinal complete denitrification. The quantitative PCR results showed that intestinal gene abundance of nirK, nosZ (encoding the copper nitrite reductase and N2O reductase, respectively were significantly increased with the presence of decaying cyanobacteria. In contrast nirS (encoding the cytochrome cd1 heme nitrite reductase and the total bacteria decreased. In the gut of Chironomus plumosus, the diversity and richness of nosZ and nirK were lower with the cyanobacteria. Phylogenetic analysis of the intestinal function genes (nosZ and nirK showed that the nosZ- and nirK-type denitrifying bacterial sequences were related to different phylotypes. Hence, additional cyanobacteria increased the abundance, but decreased the richness and diversity of intestinal nitrate-reducing bacteria, probably by providing more carbon source in the gut. The data obtained in this study elucidates that the decaying cyanobacteria decreased the emissions of N2O by the aquatic invertebrates in freshwater sediment and could serve as a valuable resource for nitrogen removal affecting greenhouse gas emissions.

  2. Impact of tillage on N2O and CO2 efflux in an agricultural crop

    Science.gov (United States)

    Lognoul, Margaux; Theodorakopoulos, Nicolas; Hiel, Marie-Pierre; Heinesch, Bernard; Bodson, Bernard; Aubinet, Marc

    2016-04-01

    In an experiment conducted in the Belgian loess belt between June and October 2015, the effect of two tillage treatments (CT - conventional tillage and RT - reduced tillage) on CO2 and N2O fluxes exchanged by a maize crop were compared. The experimental site included two parcels subjected to crop residues incorporation and to their respective tillage treatment (CT and RT) since 2008. Fluxes were measured using two fully automated sets of dynamic closed chambers, allowing a 4.5h temporal resolution. Soil water content and temperature were also monitored as well as pH, total N (TN) and total organic C (TOC) content. Results suggest that tillage practices significantly impacted emissions of both gases, with average soil respiration twice as large for RT than CT (91 μg C.m-2.s-1 versus 44.5 μg C.m-2.s-1) and N2O fluxes 8 times greater for RT than CT (5.55 ng N2O_N.m-2.s-1 versus 0.68 ng N2O_N.m-2.s-1). These observations could be explained by an effect of tillage treatment on stratification of crop residues within the soil profile, as shown in our experiment. Indeed significantly higher TN and TOC content were measured in the surface layer (0-10cm) under RT and that might have enhanced microbial activity responsible for CO2 and N2O production. A single N2O emission burst was observed in both treatments, most likely triggered by a sudden and important increase of soil moisture with a time delay of 4.5h for RT and 27h for CT. Here again, peak mean emissions were 9 times larger for RT than for CT (13.3 ng N2O_N.m-2.s-1 versus 1.43 ng N2O_N.m-2.s-1 for CT). The absence of peak emissions later during the experiment, despite the occurrence of similar soil moisture increases suggests that such increase is not the sole condition to generate N2O bursts. In the present case, it is possible that the absence of further peaks was due to a non-availability of soil N caused by increased competition for N because of maize growth. The system of automated chambers proved it

  3. Sulfide-driven autotrophic denitrification significantly reduces N2O emissions.

    Science.gov (United States)

    Yang, Weiming; Zhao, Qing; Lu, Hui; Ding, Zhi; Meng, Liao; Chen, Guang-Hao

    2016-03-01

    The Sulfate reduction-Autotrophic denitrification-Nitrification Integrated (SANI) process build on anaerobic carbon conversion through biological sulfate reduction and autotrophic denitrification by using the sulfide byproduct from the previous reaction. This study confirmed extra decreases in N2O emissions from the sulfide-driven autotrophic denitrification by investigating N2O reduction, accumulation, and emission in the presence of different sulfide/nitrate (S/N) mass ratios at pH 7 in a long-term laboratory-scale granular sludge autotrophic denitrification reactor. The N2O reduction rate was linearly proportional to the sulfide concentration, which confirmed that no sulfide inhibition of N2O reductase occurred. At S/N = 5.0 g-S/g-N, this rate resulted by sulfide-driven autotrophic denitrifying granular sludge (average granule size = 701 μm) was 27.7 mg-N/g-VSS/h (i.e., 2 and 4 times greater than those at 2.5 and 0.8 g-S/g-N, respectively). Sulfide actually stimulates rather than inhibits N2O reduction no matter what granule size of sulfide-driven autotrophic denitrifying sludge engaged. The accumulations of N2O, nitrite and free nitrous acid (FNA) with average granule size 701 μm of sulfide-driven autotrophic denitrifying granular sludge engaged at S/N = 5.0 g-S/g-N were 4.7%, 11.4% and 4.2% relative to those at 3.0 g-S/g-N, respectively. The accumulation of FNA can inhibit N2O reduction and increase N2O accumulation during sulfide-driven autotrophic denitrification. In addition, the N2O gas emission level from the reactor significantly increased from 14.1 ± 0.5 ppmv (0.002% of the N load) to 3707.4 ± 36.7 ppmv (0.405% of the N load) as the S/N mass ratio in the influent decreased from 2.1 to 1.4 g-S/g-N over the course of the 120-day continuous monitoring period. Sulfide-driven autotrophic denitrification may significantly reduce greenhouse gas emissions from biological nutrient removal when sulfur conversion processes are applied

  4. A study on N2O measurement characteristics using photoacoustic spectroscopy (PAS).

    Science.gov (United States)

    Kang, Soyoung; Kim, Seoungjin; Kang, Seongmin; Lee, Jeongwoo; Cho, Chang-Sang; Sa, Jea-Hwan; Jeon, Eui-Chan

    2014-08-07

    N2O, which is emitted mainly from nitrogen decomposition via bacteria, livestock manure, agricultural fertilizer use, fossil fuel combustion and waste incineration, is classified as a substance that causes significant destruction of the ozone layer. The N2O measurement methods for these emission sources may be divided into chromatography, optical, and electrical current measurements. Chromatography has been widely utilized for analyzing N2O. However, up until now, few studies have been conducted on N2O using photoacoustic spectroscopy. Therefore, this study aimed to evaluate performance of photoacoustic spectroscopy in this regard based on laboratory and field test results. The repeatability of photoacoustic spectroscopy was measured at 1.12%, which is lower than the repeatability of 3.0% suggested by the ISO 1564 standard, so, it has shown an excellent repeatability. The detection limit was determined to be 0.025 ppm, and the response time was confirmed to be 3 min and 26 s. The results of comparison between these measurements and GC show that the latter has superior accuracy, but mobility and convenience are superior for PAS. On the contrary, GC has a continuous measurement limitation, but PAS makes it possible to conduct continuous measurements. Therefore, PAS can be extremely useful to confirm the characteristics of N2O emissions and to quantify their amount.

  5. A Study on N2O Measurement Characteristics Using Photoacoustic Spectroscopy (PAS

    Directory of Open Access Journals (Sweden)

    Soyoung Kang

    2014-08-01

    Full Text Available N2O, which is emitted mainly from nitrogen decomposition via bacteria, livestock manure, agricultural fertilizer use, fossil fuel combustion and waste incineration, is classified as a substance that causes significant destruction of the ozone layer. The N2O measurement methods for these emission sources may be divided into chromatography, optical, and electrical current measurements. Chromatography has been widely utilized for analyzing N2O. However, up until now, few studies have been conducted on N2O using photoacoustic spectroscopy. Therefore, this study aimed to evaluate performance of photoacoustic spectroscopy in this regard based on laboratory and field test results. The repeatability of photoacoustic spectroscopy was measured at 1.12%, which is lower than the repeatability of 3.0% suggested by the ISO 1564 standard, so, it has shown an excellent repeatability. The detection limit was determined to be 0.025 ppm, and the response time was confirmed to be 3 min and 26 s. The results of comparison between these measurements and GC show that the latter has superior accuracy, but mobility and convenience are superior for PAS. On the contrary, GC has a continuous measurement limitation, but PAS makes it possible to conduct continuous measurements. Therefore, PAS can be extremely useful to confirm the characteristics of N2O emissions and to quantify their amount.

  6. Effect of fertilizer nitrogen management on N2O emissions in commercial corn fields

    International Nuclear Information System (INIS)

    Zebarth, B.J.; Rochette, P.; Burton, D.L.; Price, M.

    2008-01-01

    Corn crops receive higher fertilizer nitrogen (N) application rates than many other crops. Pre-sidedress soil nitrate tests (PSNT) are used to determine how much fertilizer N is applied at the sidedress of corn crops, and can provide an opportunity to reduce fertilizer N application rates and delay the timing of fertilizer N applications which contribute to nitrous oxide (N 2 O) emissions into the atmosphere. This study examined how the rate and time of fertilizer N application influence N 2 O emissions in corn crops grown in alluvial soils in Atlantic Canada. Starter fertilizer was applied at 45 and 59 kg N per hectare (ha) in 2004 and 2005. Treatments included the application of 75 or 150 kg N per ha banded at a sidedress, and 150 kg N per ha broadcast at the emergence of the crops. Soil mineral N content was measured using a soil core method. Cumulative N 2 O emissions were calculated using a linear interpolation method between sampling dates. Results showed that delays in fertilizer application to the sidedress, and reductions in fertilizer N application reduced nitrate (NO 3 ) intensity but had no impact on cumulative N 2 O emissions. It was concluded that further research is needed to understand controls on denitrification and N 2 O emissions. 28 refs., 2 tabs., 3 figs

  7. N2O Emissions from an Apple Orchard in the Coastal Area of Bohai Bay, China

    Directory of Open Access Journals (Sweden)

    Baohua Xie

    2014-01-01

    Full Text Available Using static chambers and gas chromatography, nitrous oxide (N2O fluxes from an apple orchard soil in the Bohai Bay region of China were measured from February 2010 to February 2011. In this study, two nitrogen (N fertilizer treatments were designed—without (CK or with (SN synthetic N fertilizers (800 kg N ha−1. The annual cumulative N2O emissions from CK and SN were 34.6 ± 3.0 (mean ± standard error and 44.3 ± 6.0 kg N2O–N ha−1, respectively. Such high emissions resulted from the intensive N fertilization in the experimental and previous years. The direct emission factor (EFd of N2O induced by the applied synthetic N fertilizers was 1.2%. The EFd is within the range of previous studies carried out in other croplands, which suggests that it is reasonable to estimate regional N2O emissions from apple orchards using the EFd obtained in other croplands. In addition, significant positive correlations existed between N2O fluxes and soil temperatures or soil dissolved organic carbon contents.

  8. Phase coexistence and exchange-bias effect in LiM n2O4 nanorods

    Science.gov (United States)

    Zhang, X. K.; Yuan, J. J.; Xie, Y. M.; Yu, Y.; Kuang, F. G.; Yu, H. J.; Zhu, X. R.; Shen, H.

    2018-03-01

    In this paper, the magnetic properties of LiM n2O4 nanorods with an average diameter of ˜100 nm and length of ˜1 μ m are investigated. The temperature dependences of dc and ac susceptibility measurements show that LiM n2O4 nanorods experience multiple magnetic phase transitions upon cooling, i.e., paramagnetic (PM), antiferromagnetic (AFM), canted antiferromagnetic (CAFM), and cluster spin glass (SG). The coexistence between a long-range ordered AFM phase due to a M n4 +-M n4 + interaction and a cluster SG phase originating from frozen AFM clusters at low temperature in LiM n2O4 nanorods is elucidated. Field-cooled hysteresis loops (FC loops) and magnetic training effect (TE) measurements confirm the presence of an exchange-bias (EB) effect in LiM n2O4 nanorods below the Néel temperature (TN˜60 K ) . Furthermore, by analyzing the TE, we conclude that the observed EB effect originates completely from an exchange coupling interaction at the interface between the AFM and cluster SG states. A phenomenological model based on phase coexistence is proposed to interpret the origin of the EB effect below 60 K in the present compound. In turn, the appearance of the EB effect further supports the coexistence of AFM order along with a cluster SG state in LiM n2O4 nanorods.

  9. Nitrogen and phosphorus addition impact soil N2O emission in a secondary tropical forest of South China

    Science.gov (United States)

    Wang, Faming; Li, Jian; Wang, Xiaoli; Zhang, Wei; Zou, Bi; Neher, Deborah A.; Li, Zhian

    2014-01-01

    Nutrient availability greatly regulates ecosystem processes and functions of tropical forests. However, few studies have explored impacts of N addition (aN), P addition (aP) and N×P interaction on tropical forests N2O fluxes. We established an N and P addition experiment in a tropical forest to test whether: (1) N addition would increase N2O emission and nitrification, and (2) P addition would increase N2O emission and N transformations. Nitrogen and P addition had no effect on N mineralization and nitrification. Soil microbial biomass was increased following P addition in wet seasons. aN increased 39% N2O emission as compared to control (43.3 μgN2O-N m−2h−1). aP did not increase N2O emission. Overall, N2O emission was 60% greater for aNP relative to the control, but significant difference was observed only in wet seasons, when N2O emission was 78% greater for aNP relative to the control. Our results suggested that increasing N deposition will enhance soil N2O emission, and there would be N×P interaction on N2O emission in wet seasons. Given elevated N deposition in future, P addition in this tropical soil will stimulate soil microbial activities in wet seasons, which will further enhance soil N2O emission. PMID:25001013

  10. Factors controlling regional differences in forest soil emission of nitrogen oxides (NO and N2O)

    DEFF Research Database (Denmark)

    Pilegaard, K.; Skiba, U.; Ambus, P.

    2006-01-01

    Soil emissions of NO and N2O were measured continuously at high frequency for more than one year at 15 European forest sites as part of the EU-funded project NOFRETETE. The locations represent different forest types (coniferous/deciduous) and different nitrogen loads. Geoaphically they range from...... with the C/N ratio. The difference in N-oxide emissions from soils of coniferous and deciduous forests may partly be explained by differences in N-deposition rates and partly by differences in characteristics of the litter layer and soil. NO was mainly derived from nitrification whereas N2O was mainly...... to a compact and moist litter layer lead to N2O production and NO consumption in the soil. The two factors soil moisture and soil temperature are often explaining most of the temporal variation within a site. When comparing annual emissions on a regional scale, however, factors such as nitrogen deposition...

  11. [Influence of planting density and precipitation on N2O emission from a winter wheat field].

    Science.gov (United States)

    Huang, Y; Jiang, J; Zong, L; Zhou, Q; Sass, R L; Fisher, F M

    2001-11-01

    To investigate the impact of plant density on N2O emission from winter wheat field and the cause of seasonal variation in the emission, field experiment with four planting rates of 0, 90, 180 and 270 kg/ha was conducted at the Jiangning County near Nanjing during 1999-2000 winter wheat growing season. Data of the field measurements indicated that the N2O emission rates during the season from planting to overwintering were not influenced by the plant density, while the emission was positively correlated with the planting density during the season from turning green to maturity. The emissions from the field plots with planting rates of 0 and 90 kg/ha were not found to be significantly different. A further analysis suggested that the seasonal variation of N2O emission be mainly influenced by precipitation, which could be quantitatively described by an exponential function of a weighted average precipitation of 6-day period before measurement.

  12. Evidence for denitrification as main source of N2O emission from residue-amended soil

    DEFF Research Database (Denmark)

    Li, Xiaoxi; Sørensen, Peter; Olesen, Jørgen Eivind

    2016-01-01

    Catch crops, especially leguminous catch crops, may increase crop nitrogen (N) supply and decrease environmental impacts in cropping systems, but they may also stimulate nitrous oxide (N2O) emissions following spring incorporation. In this 28-day laboratory incubation study, we examined the carbon...... (C) and N dynamics and N2O evolution after simulated incorporation of residues from three catch crop species into a loamy sand soil, with variable soil moisture (40, 50 or 60% water-filled pore space (WFPS)). The catch crops include two leguminous (red clover and winter vetch) and one non-leguminous...... species (ryegrass). Plant material was placed in a discrete layer surrounded by soil in which the nitrate View the MathML source pool was enriched with 15N to distinguish N2O derived from denitrification and nitrification. Net N mineralisation from leguminous catch crops was significant (30–48 mg N kg−1...

  13. Modulation of Protein Metabolism to Mitigate Nitrous Oxide (N2O) Emission from Excreta of Livestock.

    Science.gov (United States)

    Zhao, Guangyong

    2017-01-01

    Dietary protein is the main source of the body needed protein for animals. A great number of domestic animals including cattle, sheep, goats, pigs and chicken and other species are raised in the world to supply meat, milk and eggs that contain high quality of protein for human consumption. Domestic animals consume a great amount of feeds and water and excrete a large amount of faeces and urine. The conversion rate of dietary nitrogen (N, mainly dietary protein) to product N in livestock is low and the amount of N excretion is high and the nitrogenous compounds in excreta can be used as materials for nitrous oxide (N2O) formation in the processes of nitrification and denitrification in storage of excreta. Hence livestock farms and grazing pastures are important sources of N2O. N2O is a potent greenhouse gas and the key factor that damages the ozonosphere of the earth. Therefore, it is urgent to reveal the dietary protein metabolism processes and the regulation mechanism, which will help to reduce N2O emission. The nutritional options to reduce N excretion from livestock and consequently N2O emission include feeding low N rations and supplementing essential amino acid (AA) such as lysine and methionine to balance the AA profile of rations for pigs and ruminants. Other options include regulating partition of N excretion from urine to faeces and urinary nitrogenous constituents by decreasing urea N and increasing hippuric acid in ruminants. Supplementing tannic acid in the ration of ruminants has the potential to decrease the ratio of urinary N/faecal N and regulate the urinary nitrogenous components of ruminants and possibly reduce N2O emission in storage of excreta. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  14. Measuring and modeling of soil N2O emissions - How well are we doing?

    Science.gov (United States)

    Butterbach-Bahl, K.; Ralf, K.; Werner, C.; Wolf, B.

    2017-12-01

    Microbial processes in soils are the primarily source of atmospheric N2O. Fertilizer use to boost food and feed production of agricultural systems as well as nitrogen deposition to natural and semi-natural ecosystems due to emissions of NOx and NH3 from agriculture and energy production and re-deposition to terrestrial ecosystems has likely nearly doubled the pre-industrial source strength of soils for atmospheric N2O. Quantifying soil emissions and identifying mitigation options is becoming a major focus in the climate debate as N2O emissions from agricultural soils are a major contributor to the greenhouse gas footprint of agricultural systems, with agriculture incl. land use change contributing up to 30% to total anthropogenic GHG emissions. The increasing number of annual datasets show that soil emissions a) are largely depended on soil N availability and thus e.g. fertilizer application, b) vary with management (e.g. timing of fertilization, residue management, tillage), c) depend on soil properties such as organic matter content and pH, e) are affected by plant N uptake, and e) are controlled by environmental factors such as moisture and temperature regimes. It is remarkable that the magnitude of annual emissions is largely controlled by short-term N2O pulses occurring due to fertilization, wetting and drying or freezing and thawing of soils. All of this contributes to a notorious variability of soil N2O emissions in space and time. Overcoming this variability for quantification of source strengths and identifying tangible mitigation options requires targeted measuring approaches as well as the translation of our knowledge on mechanisms underlying emissions into process oriented models, which finally might be used for upscaling and scenario studies. This paper aims at reviewing current knowledge on measurements, modelling and upscaling of soil N2O emissions, thereby identifying short comes and uncertainties of the various approaches and fields for future

  15. Quantifying uncertainties in N(2O emission due to N fertilizer application in cultivated areas.

    Directory of Open Access Journals (Sweden)

    Aurore Philibert

    Full Text Available Nitrous oxide (N(2O is a greenhouse gas with a global warming potential approximately 298 times greater than that of CO(2. In 2006, the Intergovernmental Panel on Climate Change (IPCC estimated N(2O emission due to synthetic and organic nitrogen (N fertilization at 1% of applied N. We investigated the uncertainty on this estimated value, by fitting 13 different models to a published dataset including 985 N(2O measurements. These models were characterized by (i the presence or absence of the explanatory variable "applied N", (ii the function relating N(2O emission to applied N (exponential or linear function, (iii fixed or random background (i.e. in the absence of N application N(2O emission and (iv fixed or random applied N effect. We calculated ranges of uncertainty on N(2O emissions from a subset of these models, and compared them with the uncertainty ranges currently used in the IPCC-Tier 1 method. The exponential models outperformed the linear models, and models including one or two random effects outperformed those including fixed effects only. The use of an exponential function rather than a linear function has an important practical consequence: the emission factor is not constant and increases as a function of applied N. Emission factors estimated using the exponential function were lower than 1% when the amount of N applied was below 160 kg N ha(-1. Our uncertainty analysis shows that the uncertainty range currently used by the IPCC-Tier 1 method could be reduced.

  16. Assessment of online monitoring strategies for measuring N2O emissions from full-scale wastewater treatment systems.

    Science.gov (United States)

    Marques, Ricardo; Rodriguez-Caballero, A; Oehmen, Adrian; Pijuan, Maite

    2016-08-01

    Clark-Type nitrous oxide (N2O) sensors are routinely used to measure dissolved N2O concentrations in wastewater treatment plants (WWTPs), but have never before been applied to assess gas-phase N2O emissions in full-scale WWTPs. In this study, a full-scale N2O gas sensor was tested and validated for online gas measurements, and assessed with respect to its linearity, temperature dependence, signal saturation and drift prior to full-scale application. The sensor was linear at the concentrations tested (0-422.3, 0-50 and 0-10 ppmv N2O) and had a linear response up to 2750 ppmv N2O. An exponential correlation between temperature and sensor signal was described and predicted using a double exponential equation while the drift did not have a significant influence on the signal. The N2O gas sensor was used for online N2O monitoring in a full-scale sequencing batch reactor (SBR) treating domestic wastewater and results were compared with those obtained by a commercial online gas analyser. Emissions were successfully described by the sensor, being even more accurate than the values given by the commercial analyser at N2O concentrations above 500 ppmv. Data from this gas N2O sensor was also used to validate two models to predict N2O emissions from dissolved N2O measurements, one based on oxygen transfer rate and the other based on superficial velocity of the gas bubble. Using the first model, predictions for N2O emissions agreed by 98.7% with the measured by the gas sensor, while 87.0% similarity was obtained with the second model. This is the first study showing a reliable estimation of gas emissions based on dissolved N2O online data in a full-scale wastewater treatment facility. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Preliminary Measurements Of N2O Partial Pressures In Rivers of Amazon Basin, Brazil

    Science.gov (United States)

    Oliveira, C. B.; Rasera, M. F.; Krusche, A. V.; Victoria, R. L.; Richey, J. E.; Cunha, H. B.; Gomes, B. M.

    2006-12-01

    The concentrations of nitrous oxide (N2O), an important component of the greenhouse effect and with a long residence time in the atmosphere, have significantly increased in this century. The reasons for this atmospheric increase in N2O are still partially unexplained. This uncertainty is worse in relation to aquatic environments. Here we report on preliminary measurements of N2O partial pressures in rivers of the Amazon basin. The study areas are in the state of Rondonia (rivers Ji Parana, Urupa, Comemoracao and Pimenta Bueno) and Amazonas (rivers Solimoes and Negro). The rivers were sampled from October 2005 to April 2006, using with immersion pumps, lowered in the middle of the channel to 60% of total depth. Water was pumped directly into a 1 l plastic bottle, which was overflown three times before closing. Using syringes, 60 ml of N2 were injected into the bottle, simultaenously to the withdrawn of 60 ml of sample. N2O was extracted into these 60 ml of N2 by shaking vigorously for 2 minutes. With the same syringes, the gas was taken from the bottles and injected into sealed evacuated 25 ml vials. Atmospheric samples were taken from one meter above the water column and stored the same way. N2O partial pressures were determined on a Shimadzu GC-14 Green House Gas Analyzer. All rivers showed little variations in N2O partial pressures. Average values in the rivers of Rondonia were around 0.41 ± 0.07 μ atm (n=46), whereas the Solimoes and Negro rivers, in the state of Amazonas, showed values around 0.43 ± 0.08 μ atm (n=131). Atmospheric averages were approximately 0.34 ± 0.04 μ atm (n=58) and 0.32 ± 0.03 μ atm (n=134) in the states of Rondonia and Amazonas, respectively. This means that, although these waters are supersatured in CO2, making evasive fluxes of this gas an important component of the C cycle in this basin, the same does not occur in the N cycle. Small differences in partial pressures of N2O between water and air will result in small fluxes of

  18. Optimizing biochars to mitigate N2O emissions in Mediterranean areas

    Science.gov (United States)

    Cayuela, Maria Luz; Sanchez-Garcia, Maria; Roig, Asuncion; Sanchez-Monedero, Miguel Angel

    2017-04-01

    Some of the most productive agricultural soils stand in Mediterranean-type climate areas of the world (e.g. California's Central Valley, Andalucia region in South Spain, and Lombardy region in Italy). Many of these soils are under intensive agricultural production, bearing the addition of substantial amounts of N fertilizers, which are known to promote soil N2O emissions. Laboratory studies have shown the potential of biochar to decrease N2O emissions in soils from Mediterranean areas. These soils generally have alkaline pH and low concentrations of organic C and several laboratory experiments found that applying biochar at a rate of 2% in weight could decrease N2O emissions up to 90%. However, field studies carried out in areas of California, Italy and Spain (all under Mediterranean climate) showed none or very limited N2O mitigation with biochar. We postulate that this discrepancy may be because biochar-soil combinations were not optimal in field studies and that developing biochars adjusted to specific soil properties is crucial for their successful application to mitigate N2O emissions. Thus, in this study we aimed at (i) collecting and characterizing a variety of the most representative Mediterranean agricultural residues (olive tree, almond and orange tree pruning, olive mill waste, rice straw, horticultural residues, etc.), (ii) exploring their suitability as feedstocks for biochar production and (iii) analyzing their impact on N2O emissions in a Mediterranean agricultural soil. Biochars were produced by slow pyrolysis with a heating rate of 5˚C min-1 at two pyrolysis temperatures (400 and 600˚C) and a retention time of two hours. Soil incubations were set up simulating conditions of highly intensive crop production (high N fertilization, high moisture) to test how the biochars produced from different feedstocks and under two pyrolysis temperatures influence N2O emissions. Our starting hypothesis was that it is possible to optimize biochar characteristics

  19. Catalytic reduction of N2O over Ag-Pd/Al2O3 bimetallic catalysts.

    Science.gov (United States)

    Tzitzios, V K; Georgakilas, V

    2005-05-01

    A study of the catalytic conversion of N2O to N2 over a bimetallic Ag-Pd catalyst is described in this article. Several Ag-Pd catalytic systems were prepared supported on Al2O3 with different ratios and their catalytic activity for the direct decomposition of N2O and their reduction with CO was measured. Based on the experimental results, it was observed that Ag-Pd bimetallic catalyst (5-0.5%) was the most active for both nitrous oxide reduction and direct decomposition. This high activity seems to be connected with a synergistic effect between Ag and Pd.

  20. No effect of cropping system on the greenhouse gas N2O

    DEFF Research Database (Denmark)

    Carter, Mette Sustmann; Chirinda, N.

    2009-01-01

    Organic farming is comparable to conventional in terms of field emissions of the strong greenhouse gas nitrous oxide (N2O). Our study points to the need for increased yields in organic farming as measure to reduced emissions per unit of produce.......Organic farming is comparable to conventional in terms of field emissions of the strong greenhouse gas nitrous oxide (N2O). Our study points to the need for increased yields in organic farming as measure to reduced emissions per unit of produce....

  1. Modeling of Chemical Reactions in Afterburning for the Reduction of N2O

    DEFF Research Database (Denmark)

    Gustavsson, Lennart; Glarborg, Peter; Leckner, Bo

    1996-01-01

    Full scale tests in a 12 MW fluidized bed combustor on reduction of N2O by secondary fuel injection are analyzed in terms a model that involves a detailed reaction mechanism for the gas phase chemistry as well as a description of gas-solid reactions.......Full scale tests in a 12 MW fluidized bed combustor on reduction of N2O by secondary fuel injection are analyzed in terms a model that involves a detailed reaction mechanism for the gas phase chemistry as well as a description of gas-solid reactions....

  2. Fertilización y N2O. Implicaciones en la huella de carbono.

    OpenAIRE

    Vallejo Garcia, Antonio; Ábalos Rodríguez, Diego; Téllez del Río, Ángela; Guardia, Guillermo

    2013-01-01

    Todos los alimentos obtenidos de origen vegetal llevan asociada una cierta cantidad de emisiones de Gases de Efecto Invernadero (GEI), que se cuantifican a través de su huella de carbono. De los GEI, la agricultura es principalmente responsable de la emisión de óxido nitroso (N2O), que es el que presenta mayor poder de calentamiento global. La metodología del IPCC, aparte de sobreestimar con su valor por defecto las emisiones de N2O de nuestros agrosistemas, no tiene en cuenta el fin último d...

  3. Effect of granulated wood ash fertilization on N2O emissions in boreal peat forests

    Science.gov (United States)

    Liimatainen, Maarit; Martikainen, Pertti J.; Hytönen, Jyrki; Maljanen, Marja

    2016-04-01

    Peatlands cover one third of the land surface area in Finland and over half of that are drained for forestry. Natural peatlands are either small sources of nitrous oxide (N2O) or they can also act as a sinks of N2O. When peatlands are drained, oxygen concentration in the peat increases, organic matter decomposition accelerates and N2O emissions may increase significantly, especially in nutrient rich peat soils. Hence drainage and land-use changes can have a big impact on N2O fluxes in peatlands. The annual consumption of wood chips is to be increased to 13.5 M m3 from the present 8.7 M m3 in Finland. This will also increase the amount of wood ash in the power plants. Wood ash contains considerable amounts of mineral nutrients but lacks nitrogen. Therefore, it has been used as a fertilizer in nitrogen rich peatland forests lacking other nutrients. Recycling of ash would also return the nutrients lost during biomass harvesting back to the forests. We studied the effects of granulated wood ash as a fertilizer in peat soils drained for forestry. Ash is nowadays granulated mainly to facilitate its handling and spreading. Granulation also stabilizes the ash decreasing the solubility of most of the nutrients and minimizing harmful effects of ash spread over the vegetation. Granulated wood ash increases soil pH less than loose ash. Drainage of peatland forests increases microbial activity in the soil which is furthermore intensified with the addition of ash promoting organic matter decomposition and possibly affecting N2O emissions. We studied the effect of granulated wood ash on N2O fluxes in three different peat forests in Finland in both field and laboratory experiments. In the field, N2O emissions were not affected by granulated wood ash fertilization but the soil respiration rate increased. However, in the laboratory studies we observed a clear decrease in N2O production due to wood ash addition, although changes in pH values were only minor. We studied what could

  4. Greenhouse Gas (CO2 AND N2O Emissions from Soils: A Review Emisión de Gases invernadero (CO2 y N2O desde Suelos

    Directory of Open Access Journals (Sweden)

    Cristina Muñoz

    2010-09-01

    Full Text Available In agricultural activities, the main greenhouse gases (GHG are those related to C and N global cycles. The impact of agriculture on GHG emissions has become a key issue, especially when considering that natural C and N cycles are influenced by agricultural development. This review focuses on CO2 and N2O soil emissions in terrestrial ecosystems, with emphasis in Chilean and similar agro-ecosystems around the world. The influence of land use and crop management practices on CO2 and N2O emissions is analyzed; some mitigation measures to reduce such emissions are also discussed here. More knowledge on the biological processes that promote of GHG emissions from soil will allow creating opportunities for agricultural development under friendly-environmental conditions, where soil can act as a reservoir and/or emitter of GHG, depending on the balance of inputs and outputs.En actividades agrícolas los principales gases de efecto invernadero (GHG son los relacionados con los ciclos globales de C y N. El impacto de la agricultura sobre las emisiones GHG se ha convertido en una cuestión clave, especialmente si se considera que los ciclos naturales C y N se ven influidos por el desarrollo agrícola. Esta revisión se centra en emisiones de CO2 y N2O del suelo en los ecosistemas terrestres, con énfasis en agro-ecosistemas de Chile y similares alrededor del mundo. Se analiza la influencia del uso del suelo y las prácticas de manejo del cultivo sobre emisiones de CO2 y N2O, se discuten medidas de mitigación para reducir estas emisiones. Un mayor conocimiento sobre los procesos biológicos que promueven las emisiones GHG del suelo permitirá la creación de oportunidades para el desarrollo agrícola en condiciones ambientalmente amigables, donde el suelo puede actuar como un reservorio y/o emisor de GHG, dependiendo del balance de entradas y salidas.

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

    Directory of Open Access Journals (Sweden)

    B. Guieysse

    2013-10-01

    Full Text Available 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.

  6. Effects of Corn Straw Returning and Nitrogen Fertilizer Application Methods on N2O Emission from Wheat Growing Season

    Directory of Open Access Journals (Sweden)

    XU Yu

    2015-12-01

    Full Text Available Based on a wheat field experiment, the effect of four treatments such as no-straw returning (SN, straw returning (SR, control release fertilizer application(SRC and nitrogen drilling(SRR on N2O emission was studied using the static chamber method and the gas chromatographic technique. The results indicated that the wheat field was the sources of N2O emission. The N2O emission peaks followed each time of fertilizer application and irrigation, and usually continued for 1~2 weeks. N2O emissions accounted for more than 40% of total emissions during the N2O emission peak. The amount of N2O emission during three growing stage of wheat from high to low was arranged in turn pre-wintering period, post-wintering period and wintering period. N2O emission could be increased by straw returning. Compared with SN, N2O emission could be enhanced by 48.6% under SR. Both SRC and SRR could decrease the N2O emission, increase wheat yield and economic benefit, especially the latter. Nitrogen drilling is a good method for yield increment and N2O abatement.

  7. Quantifying N2O emissions and production pathways from fresh waste during the initial stage of disposal to a landfill.

    Science.gov (United States)

    Wang, Xiaojun; Jia, Mingsheng; Zhang, Han; Pan, Songqing; Kao, Chih Ming; Chen, Shaohua

    2017-05-01

    Intensive nitrous oxide (N 2 O) emissions usually occur at the working face of landfills. However, the specific amounts and contributions of the multiple pathways to N 2 O emissions are poorly understood. N 2 O emissions and the mutual conversions of N-species in both open and sealed simulated landfill reactors filled with fresh refuse were examined during a 100-h incubation period, and N 2 O sources were calculated using 15 N isotope labelling. N 2 O peak fluxes were above 70μgNkg -1 waste h -1 for both treatments. The sealed incubation reactors became a N 2 O sink when N 2 O in the ambient environment was sufficient. The total amount of N 2 O emissions under sealed conditions was 2.15±0.56mgNkg -1 waste, which was higher than that under open conditions (1.91±0.34mgNkg -1 waste). The NO 2 - peak appeared prior to the peak in N 2 O flux. The degree and duration of total nitrogen reduction in open incubations were larger and longer than those of sealed incubations and could possibly be due to oxygen supplementation. Denitrification (DF) was a major source of N 2 O generation during these incubations. The contribution of the DF pathway decreased from 89.2% to 61.3% during the open incubations. The effects of nitrification (NF) and nitrification-coupled denitrification (NCD) increased during the increasing phase and the decreasing phase of N 2 O flux, contributing 24.1-37.4% and 31.7-34.4% of total N 2 O emissions, respectively. In sealed treatments, the DF pathway accounted for more than 90% of the total N 2 O emission during the entire incubation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. A flexible Bayesian model for describing temporal variability of N2O emissions from an Australian pasture

    International Nuclear Information System (INIS)

    Huang, Xiaodong; Grace, Peter; Rowlings, David; Mengersen, Kerrie

    2013-01-01

    Soil-based emissions of nitrous oxide (N 2 O), a well-known greenhouse gas, have been associated with changes in soil water-filled pore space (WFPS) and soil temperature in many previous studies. However, it is acknowledged that the environment–N 2 O relationship is complex and still relatively poorly unknown. In this article, we employed a Bayesian model selection approach (Reversible jump Markov chain Monte Carlo) to develop a data-informed model of the relationship between daily N 2 O emissions and daily WFPS and soil temperature measurements between March 2007 and February 2009 from a soil under pasture in Queensland, Australia, taking seasonal factors and time-lagged effects into account. The model indicates a very strong relationship between a hybrid seasonal structure and daily N 2 O emission, with the latter substantially increased in summer. Given the other variables in the model, daily soil WFPS, lagged by a week, had a negative influence on daily N 2 O; there was evidence of a nonlinear positive relationship between daily soil WFPS and daily N 2 O emission; and daily soil temperature tended to have a linear positive relationship with daily N 2 O emission when daily soil temperature was above a threshold of approximately 19 °C. We suggest that this flexible Bayesian modeling approach could facilitate greater understanding of the shape of the covariate-N 2 O flux relation and detection of effect thresholds in the natural temporal variation of environmental variables on N 2 O emission. - Highlights: • A Bayesian model selection approach was used to develop a data-informed model. • Daily soil temperature influenced N 2 O flux above approximately 19 °C. • The effects of daily WFPS on N 2 O flux were complex and changeable. • Daily N 2 O flux was also significantly related to a complex seasonal pattern. • The approach facilitated understanding of the temporal variations of variables on N 2 O

  9. Inverse modelling of European N2O emissions: assimilating observations from different networks

    NARCIS (Netherlands)

    Corazza, M.; Bergamaschi, P.; Vermeulen, A.T.; Krol, M.C.

    2011-01-01

    We describe the setup and first results of an inverse modelling system for atmospheric N2O, based on a four-dimensional variational (4DVAR) technique and the atmospheric transport zoom model TM5. We focus in this study on the European domain, utilizing a comprehensive set of quasi-continuous

  10. Global trends and uncertainties in terrestrial denitrification and N2O emissions

    NARCIS (Netherlands)

    Bouwman, A.F.; Beusen, A.H.W.; Griffioen, J.; Groenigen, van J.W.; Hefting, M.M.; Oenema, O.; Puijenbroek, van P.J.T.M.; Seitzinger, S.; Slomp, C.P.; Stehfest, E.

    2013-01-01

    Soil nitrogen (N) budgets are used in a global, distributed flow-path model with 0.5 degrees x 0.5 degrees resolution, representing denitrification and N2O emissions from soils, groundwater and riparian zones for the period 1900-2000 and scenarios for the period 2000-2050 based on the Millennium

  11. Future trends in emissions of N2O from rivers and estuaries

    NARCIS (Netherlands)

    Kroeze, C.; Dumont, E.L.; Seitzinger, S.

    2010-01-01

    Emissions of nitrous oxide (N2O) from aquatic systems such as rivers and estuaries are enhanced as a result of human activities on land resulting in enhanced nitrogen availability in aquatic systems. These human activities include agricultural activities such as fertilizer use, as well as industrial

  12. Co-Mn-Al Mixed Oxides as Catalysts for Ammonia Oxidation to N2O.

    Czech Academy of Sciences Publication Activity Database

    Ludvíková, Jana; Jablońska, M.; Jirátová, Květa; Chmielarz, L.; Balabánová, Jana; Kovanda, F.; Obalová, L.

    2016-01-01

    Roč. 42, č. 3 (2016), s. 2669-2690 ISSN 0922-6168 R&D Projects: GA ČR GA14-13750S Institutional support: RVO:67985858 Keywords : Co-Mn-Al mixed oxides * catalytic ammonia oxidation * N2O production * mechanochemical production Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.369, year: 2016

  13. Nitrous Oxide (N2O) Emissions from Waste and Biomass to Energy Plants

    Czech Academy of Sciences Publication Activity Database

    Fernandez-Gutierrez, M.-J.; Baxter, D.; Hunter, Ch.; Svoboda, Karel

    2005-01-01

    Roč. 23, č. 2 (2005), s. 133-147 ISSN 0734-242X Institutional research plan: CEZ:AV0Z40720504 Keywords : N2O * waste * incineration Subject RIV: JE - Non-nuclear Energetics, Energy Consumption ; Use Impact factor: 0.396, year: 2005

  14. Solubility of N2O in and density, viscosity, and surface tension of aqueous piperazine solutions

    NARCIS (Netherlands)

    Derks, P. W.; Hogendoorn, K. J.; Versteeg, G. F.

    2005-01-01

    The physical solubility of N2O in and the density and viscosity of aqueous piperazine solutions have been measured over a temperature range of (293.15 to 323.15) K for piperazine concentrations ranging from about (0.6 to 1.8) kmol·mr-3. Furthermore, the present study contains experimental surface

  15. New estimates of global emissions of N2O from rivers and estuaries

    NARCIS (Netherlands)

    Kroeze, C.; Dumont, E.L.; Seitzinger, S.P.

    2005-01-01

    We present new estimates of emissions of nitrous oxide (N2O) from rivers and estuaries, using the NEWS-DIN model. NEWS-DIN is a model of the global transport of dissolved inorganic nitrogen (DIN) by rivers to coastal waters (Dumont et al. forthcoming). It calculates DIN export rates as a function of

  16. Modelling of N2O Reduction in a Circulating Fluidized Bed Boiler

    DEFF Research Database (Denmark)

    Johnsson, Jan Erik; Åmand, Lars Erik; Dam-Johansen, Kim

    1996-01-01

    quartz reactor was measured. It was found that calcined Stevns Chalk is a very active catalyst for N2O decomposition in an inert atmosphere compared to bed material, i.e. a mixture of ash and sand. However, in FBC the limestone is exposed to a mixture of gases, including CO, CO2 and SO2, and sulphation...

  17. Instream Large Wood: Dentrification Hotspots With Low N2O Production

    Science.gov (United States)

    The maintenance and restoration of forested riparian cover is important for watershed nitrogen (N) cycling. Forested riparian zones provide woody debris to streams that may stimulate in-stream denitrification and nitrous oxide (N2O) production. We examined the effects of woody an...

  18. Fire increases the risk of higher soil N2O emissions from Mediterranean Macchia ecosystems

    DEFF Research Database (Denmark)

    Karhu, Kristiina; Dannenmann, M.; Kitzler, B.

    2015-01-01

    Intensification of droughts under climate change is projected to increase fire frequency in the Mediterranean region. Fires cause direct emission of greenhouse gases (GHG) such as carbon dioxide (CO2) and nitrous oxide (N2O), due to the combustion of organic matter, creating a positive feedback...

  19. N2O Catalytic Decomposition – from Laboratory Experiment to Industry Reactor

    Czech Academy of Sciences Publication Activity Database

    Obalová, L.; Jirátová, Květa; Karásková, K.; Chromčáková, Ž.

    2012-01-01

    Roč. 191, č. 1 (2012), s. 116-120 ISSN 0920-5861 R&D Projects: GA TA ČR TA01020336 Institutional support: RVO:67985858 Keywords : N2O * catalytic decomposition * fixed bed reactor Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.980, year: 2012

  20. Edge effects on N2O, NO and CH4 fluxes in two temperate forests.

    Science.gov (United States)

    Remy, Elyn; Gasche, Rainer; Kiese, Ralf; Wuyts, Karen; Verheyen, Kris; Boeckx, Pascal

    2017-01-01

    Forest ecosystems may act as sinks or sources of nitrogen (N) and carbon (C) compounds, such as the climate relevant trace gases nitrous oxide (N 2 O), nitric oxide (NO) and methane (CH 4 ). Forest edges, which catch more atmospheric deposition, have become important features in European landscapes and elsewhere. Here, we implemented a fully automated measuring system, comprising static and dynamic measuring chambers determining N 2 O, NO and CH 4 fluxes along an edge-to-interior transect in an oak (Q. robur) and a pine (P. nigra) forest in northern Belgium. Each forest was monitored during a 2-week measurement campaign with continuous measurements every 2h. NO emissions were 9-fold higher than N 2 O emissions. The fluxes of NO and CH 4 differed between forest edge and interior, but not for N 2 O. This edge effect was more pronounced in the oak than in the pine forest. In the oak forest, edges emitted less NO (on average 60%) and took up more CH 4 (on average 177%). This suggests that landscape structure can play a role in the atmospheric budgets of these climate relevant trace gases. Soil moisture variation between forest edge and interior was a key variable explaining the magnitude of NO and CH 4 fluxes in our measurement campaign. To better understand the environmental impact of N and C trace gas fluxes from forest edges, additional and long-term measurements in other forest edges are required. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Contribution of N2O to the greenhouse gas balance of first-generation biofuels

    NARCIS (Netherlands)

    Smeets, E.W.M.; Bouwman, A.F.; Stehfest, E.; Vuuren, van P.; Posthuma, A.

    2009-01-01

    n this study, we analyze the impact of fertilizer- and manure-induced N2O emissions due to energy crop production on the reduction of greenhouse gas (GHG) emissions when conventional transportation fuels are replaced by first-generation biofuels (also taking account of other GHG emissions during the

  2. Tillage effects on N2O emissions as influenced by a winter cover crop

    DEFF Research Database (Denmark)

    Petersen, Søren O; Mutegi, James; Hansen, Elly Møller

    2011-01-01

    emissions may be more important than the effect on soil C. This study monitored emissions of N2O between September 2008 and May 2009 in three tillage treatments, i.e., conventional tillage (CT), reduced tillage (RT) and direct drilling (DD), all with (+CC) or without (−CC) fodder radish as a winter cover...... application by direct injection N2O emissions were stimulated in all tillage treatments, reaching 250–400 μg N m−2 h−1 except in the CT + CC treatment, where emissions peaked at 900 μg N m−2 h−1. Accumulated emissions ranged from 1.6 to 3.9 kg N2O ha−1. A strong positive interaction between cover crop......Conservation tillage practices are widely used to protect against soil erosion and soil C losses, whereas winter cover crops are used mainly to protect against N losses during autumn and winter. For the greenhouse gas balance of a cropping system the effect of reduced tillage and cover crops on N2O...

  3. Kinetics of Heterogeneous NO and N2O Reduction at FBC Conditions

    DEFF Research Database (Denmark)

    Johnsson, Jan Erik; Jensen, Anker; Nielsen, Jannik Steen

    1999-01-01

    of the combustion chamber and adding secondary air in the top or in the cyclone. The change in reaction pathways for N2O and NO formation and reduction is very complex, and the catalytic activity of the solid material in the boiler may vary with the air staging. Samples of solids taken from large scale tests...

  4. Interactions between microbial-feeding and predatory soil fauna trigger N2O emissions

    NARCIS (Netherlands)

    Thakur, M.P.; Groenigen, van J.W.; Kuiper, I.; Deyn, de G.B.

    2014-01-01

    Recent research has shown that microbial-feeding invertebrate soil fauna species can significantly contribute to N2O emissions. However, in soil food webs microbial-feeding soil fauna interact with each other and with their predators, which affects microbial activity. To date we lack empirical tests

  5. Prediction of N2O emission from local information with Random Forest.

    Science.gov (United States)

    Philibert, Aurore; Loyce, Chantal; Makowski, David

    2013-06-01

    Nitrous oxide is a potent greenhouse gas, with a global warming potential 298 times greater than that of CO2. In agricultural soils, N2O emissions are influenced by a large number of environmental characteristics and crop management techniques that are not systematically reported in experiments. Random Forest (RF) is a machine learning method that can handle missing data and ranks input variables on the basis of their importance. We aimed to predict N2O emission on the basis of local information, to rank environmental and crop management variables according to their influence on N2O emission, and to compare the performances of RF with several regression models. RF outperformed the regression models for predictive purposes, and this approach led to the identification of three important input variables: N fertilization, type of crop, and experiment duration. This method could be used in the future for prediction of N2O emissions from local information. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Factors controlling regional differences in forest soil emission of nitrogen oxides (NO and N2O

    Directory of Open Access Journals (Sweden)

    K. Pilegaard

    2006-01-01

    Full Text Available Soil emissions of NO and N2O were measured continuously at high frequency for more than one year at 15 European forest sites as part of the EU-funded project NOFRETETE. The locations represent different forest types (coniferous/deciduous and different nitrogen loads. Geographically they range from Finland in the north to Italy in the south and from Hungary in the east to Scotland in the west. The highest NO emissions were observed from coniferous forests, whereas the lowest NO emissions were observed from deciduous forests. The NO emissions from coniferous forests were highly correlated with N-deposition. The site with the highest average annual emission (82 μg NO-N m−2 h−1 was a spruce forest in South-Germany (Höglwald receiving an annual N-deposition of 2.9 g m−2. NO emissions close to the detection limit were observed from a pine forest in Finland where the N-deposition was 0.2 g N m−2 a−1. No significant correlation between N2O emission and N-deposition was found. The highest average annual N2O emission (20 μg N2O-N m−2 h−1 was found in an oak forest in the Mátra mountains (Hungary receiving an annual N-deposition of 1.6 g m−2. N2O emission was significantly negatively correlated with the C/N ratio. The difference in N-oxide emissions from soils of coniferous and deciduous forests may partly be explained by differences in N-deposition rates and partly by differences in characteristics of the litter layer and soil. NO was mainly derived from nitrification whereas N2O was mainly derived from denitrification. In general, soil moisture is lower at coniferous sites (at least during spring time and the litter layer of coniferous forests is thick and well aerated favouring nitrification and thus release of NO. Conversely, the higher rates of denitrification in deciduous forests due to a compact and moist litter layer lead to N2O production and NO consumption in the soil. The two factors soil moisture and soil temperature are

  7. N2O eddy covariance fluxes: From field measurements to flux calculation

    Science.gov (United States)

    Lognoul, Margaux; Debacq, Alain; Heinesch, Bernard; Aubinet, Marc

    2017-04-01

    From March to October 2016, we performed eddy covariance measurements in a sugar beet crop at the Lonzée Terrestrial Observatory (LTO, candidate ICOS site) in Belgium. N2O and H2O atmospheric concentrations were measured at 10 Hz using a quantum-cascade laser spectrometer (Aerodyne Research, Inc.) and combined to wind speed 3D components measured with a sonic anemometer (Gill HS-50). Flux computation was carried out using the EddyPro Software (LI-COR) with a focus on adaptations needed for tracers like N2O. Data filtering and quality control were performed according to Vickers and Mahrt (1997) and Mauder and Foken (2004). The flags were adapted to N2O time series. In this presentation, different computation steps will be presented. More specifically: 1) Considering that a large proportion of N2O fluxes are small (within ± 0.5 nmol m-2 s-1), the classical stationarity test might lead to excessive data filtering and in such case, some searchers have chosen to use the running mean (RM) as a detrend method over block averaging (BA) and to filter data otherwise. For our dataset, BA mean fluxes combined to the stationarity test did not significantly differ from RM fluxes when the averaging window was 300s or larger, but were significantly larger otherwise, suggesting that significant eddies occurred at the 5-min timescale and that they were not accounted for with a shorter averaging window. 2) The determination of time-lag in the case of N2O fluxes can become tricky for two reasons : (1) the signal amplitude can differ from one time period to the next, making it difficult to use the method of covariance maximization and (2) an additional clock drift can appear if the spectrometer is not logging on the same computer than the anemometer. In our case, the N2O signal was strong enough to solve both problems and to perform time-lag compensation according to the covariance maximization, with a default value equal to the mode of the lag distribution. The automatic time

  8. Effect of temperate climate tree species on gross ammonification, gross nitrification and N2O formation

    Science.gov (United States)

    Brüggemann, N.; Rosenkranz, P.; Papen, H.; Butterbach-Bahl, K.

    2003-04-01

    Microbial nitrogen turnover processes in the soil, like ammonification, nitrification and denitrification, play an important role in the formation of nitrous oxide (N2O): (i) ammonification, because it releases nitrogen from organic material in the form of ammonium (NH4+), which in turn can serve as substrate for nitrification; (ii) nitrification itself (i.e. the turnover of NH4+ to nitrate, NO3-), during which nitric oxide (NO) and N2O can be released as by-products at varying ratios; (iii) denitrification, in which NO3- serves as electron acceptor and is converted to molecular nitrogen (N2) via NO and N2O as intermediates, that can also be partially lost to the atmosphere. Temperate forest soils are a substantial source of atmospheric N2O contributing up to 10% to the total atmospheric N2O budget. However, this figure is afflicted with a huge uncertainty due to a number of factors governing the soil N2O formation, consumption, release and uptake, which are not fully understood at present. To one of these factors belongs the influence of the tree species on nitrogen turnover processes in the soil and the formation of N trace gases related with them. The aim of the present work was to analyse this tree species effect for the temperate climate region. For this purpose the effect of five different temperate tree species, having the same age and growing on the same soil in direct vicinity to each other, on gross ammonification and gross nitrification as well as on N2O formation was investigated. The trees (common beech, Fagus sylvatica; pedunculate oak, Quercus robur; Norway spruce, Picea abies; Japanese larch, Larix leptolepis; mountain pine, Pinus mugo) were part of a species trial in Western Jutland, Denmark, established in 1965 on a former sandy heathland. Samples from the soil under these five tree species were taken in spring and in summer 2002, respectively, differentiating between organic layer and mineral soil. The gross rates of ammonification as well of

  9. Oceanic nitrogen cycling and N2O flux perturbations in the Anthropocene

    Science.gov (United States)

    Landolfi, A.; Somes, C. J.; Koeve, W.; Zamora, L. M.; Oschlies, A.

    2017-08-01

    There is currently no consensus on how humans are affecting the marine nitrogen (N) cycle, which limits marine biological production and CO2 uptake. Anthropogenic changes in ocean warming, deoxygenation, and atmospheric N deposition can all individually affect the marine N cycle and the oceanic production of the greenhouse gas nitrous oxide (N2O). However, the combined effect of these perturbations on marine N cycling, ocean productivity, and marine N2O production is poorly understood. Here we use an Earth system model of intermediate complexity to investigate the combined effects of estimated 21st century CO2 atmospheric forcing and atmospheric N deposition. Our simulations suggest that anthropogenic perturbations cause only a small imbalance to the N cycle relative to preindustrial conditions (˜+5 Tg N y-1 in 2100). More N loss from water column denitrification in expanded oxygen minimum zones (OMZs) is counteracted by less benthic denitrification, due to the stratification-induced reduction in organic matter export. The larger atmospheric N load is offset by reduced N inputs by marine N2 fixation. Our model predicts a decline in oceanic N2O emissions by 2100. This is induced by the decrease in organic matter export and associated N2O production and by the anthropogenically driven changes in ocean circulation and atmospheric N2O concentrations. After comprehensively accounting for a series of complex physical-biogeochemical interactions, this study suggests that N flux imbalances are limited by biogeochemical feedbacks that help stabilize the marine N inventory against anthropogenic changes. These findings support the hypothesis that strong negative feedbacks regulate the marine N inventory on centennial time scales.

  10. Managed grassland alters soil N dynamics and N2O emissions in temperate steppe.

    Science.gov (United States)

    Xu, Lijun; Xu, Xingliang; Tang, Xuejuan; Xin, Xiaoping; Ye, Liming; Yang, Guixia; Tang, Huajun; Lv, Shijie; Xu, Dawei; Zhang, Zhao

    2018-04-01

    Reclamation of degraded grasslands as managed grasslands has been increasingly accelerated in recent years in China. Land use change affects soil nitrogen (N) dynamics and nitrous oxide (N 2 O) emissions. However, it remains unclear how large-scale grassland reclamation will impact the grassland ecosystem as a whole. Here, we investigated the effects of the conversion from native to managed grasslands on soil N dynamics and N2O emissions by field experiments in Hulunber in northern China. Soil (0-10cm), nitrate (NO 3 - ), ammonium (NH 4 + ), and microbial N were measured in plots in a temperate steppe (Leymus chinensis grassland) and two managed grasslands (Medicago sativa and Bromus inermis grasslands) in 2011 and 2012. The results showed conversion of L. chinensis grassland to M. sativa or B. inermis grasslands decreased concentrations of NO 3 - -N, but did not change NH 4 + -N. Soil microbial N was slightly decreased by the conversion of L. chinensis grassland to M. sativa, but increased by the conversion to B. inermis. The conversion of L. chinensis grassland to M. sativa (i.e., a legume grass) increased N 2 O emissions by 26.2%, while the conversion to the B. inermis (i.e., a non-legume grass) reduced N 2 O emissions by 33.1%. The conversion from native to managed grasslands caused large created variations in soil NO 3 - -N and NH 4 + -N concentrations. Net N mineralization rates did not change significantly in growing season or vegetation type, but to net nitrification rate. These results provide evidence on how reclamation may impact the grassland ecosystem in terms of N dynamics and N 2 O emissions. Copyright © 2017. Published by Elsevier B.V.

  11. Response of terrestrial N2O and NOx emissions to abrupt climate change

    International Nuclear Information System (INIS)

    Pfeiffer, Mirjam; Kaplan, Jed O

    2010-01-01

    Being a potent greenhouse gas, N 2 O emitted by the terrestrial biosphere during abrupt climate change events could have amplified externally forced warming. To investigate this possibility, we tested the sensitivity of terrestrial N 2 O emissions to an abrupt warming event by applying the ARVE-DGVM in combination with a novel scheme for process-based simulation of terrestrial N 2 O and NO x emissions at the Gerzensee site in Switzerland. In this study, we aim to quantify the magnitude of change in emissions for the abrupt climate change event that occurred at the transition from Oldest Dryas to Boel-ling during the last deglaciation. Using high-resolution multiproxy records obtained from the Gerzensee that cover the Late Glacial, we apply a prescribed vegetation change derived from the pollen record and temperature and precipitation reconstructions derived from δ 18 O in lake sediments. Changes in soil temperature and moisture are simulated by the ARVE-DGVM using the reconstructed paleoclimate as a driver. Our results show a pronounced increase in mean annual N 2 O and NO x emissions for the transition (by factor 2.55 and 1.97, respectively), with highest amounts generally being emitted during summer. Our findings suggest that summertime emissions are limited by soil moisture, while temperature controls emissions during winter. For the time between 14670 and 14620 cal. years BP, our simulated N 2 O emissions show increase rates as high as 1% per year, indicating that local reactions of emissions to changing climate could have been considerably faster than the atmospheric concentration changes observed in polar ice.

  12. Effect of N2O on nausea and vomiting via intraabdominal pressure.

    Science.gov (United States)

    Yuce, H H; Goktas, U; Kati, I; Cegin, M B; Soyoral, L

    2012-01-01

    In this study we aimed to investigate whether there is an effect of N2O on postoperative nausea and vomiting (PONV) via intraabdominal pressure (IAP). A total of 40 patients with risk class ASA I-II and age ranging between 20 and 50 years were enrolled in the study. The patients were monitored for electrocardiography (ECG), peripheral oxygen saturation (SpO2), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP), end-tidal carbon dioxide (ETCO2) and body temperature. IAP was measured by a central venous pressure manometer placed in the urine catheter. Heart rate (HR), SpO2, SBP, DBP, MBP, ETCO2, body temperature and IAP were measured before the induction of anesthesia and every 10 minutes throughout the operation. Nausea and vomiting were questioned at the first and second postoperative hours. The patients were randomly grouped into two groups. Induction in both groups was provided using 2 mg/kg propofol, 2 µg/kg fentanyl and 0.1 mg/kg vecuronium, and endotracheal intubation was performed. The maintenance of anesthesia was provided by 40 % O2 + 60 % N2O, 1-2 % sevoflurane and 50 µg fentanyl + 2 mg vecuronium every 45 minutes in the first group. In the second group, 60 % dry air was used instead of 60 % N2O. There was no significant difference in terms of HR, SpO2, SBP, MBP, ETCO2, body temperature, nausea-vomiting and IAP. In conclusion, we think that N2O usage during the general anesthesia in patients without intraabdominal problems may increase IAP level for some degree whereas it does not increase PONV. In addition, N2O usage does not change ETCO2 values (Tab. 3, Fig. 3, Ref. 32).

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

    Science.gov (United States)

    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

  14. Regulation of denitrification at the cellular level: a clue to the understanding of N2O emissions from soils

    Science.gov (United States)

    Bakken, Lars R.; Bergaust, Linda; Liu, Binbin; Frostegård, Åsa

    2012-01-01

    Denitrifying prokaryotes use NOx as terminal electron acceptors in response to oxygen depletion. The process emits a mixture of NO, N2O and N2, depending on the relative activity of the enzymes catalysing the stepwise reduction of NO3− to N2O and finally to N2. Cultured denitrifying prokaryotes show characteristic transient accumulation of NO2−, NO and N2O during transition from oxic to anoxic respiration, when tested under standardized conditions, but this character appears unrelated to phylogeny. Thus, although the denitrifying community of soils may differ in their propensity to emit N2O, it may be difficult to predict such characteristics by analysis of the community composition. A common feature of strains tested in our laboratory is that the relative amounts of N2O produced (N2O/(N2+N2O) product ratio) is correlated with acidity, apparently owing to interference with the assembly of the enzyme N2O reductase. The same phenomenon was demonstrated for soils and microbial communities extracted from soils. Liming could be a way to reduce N2O emissions, but needs verification by field experiments. More sophisticated ways to reduce emissions may emerge in the future as we learn more about the regulation of denitrification at the cellular level. PMID:22451108

  15. Options and potentials to mitigate N2O emissions from wheat and maize fields in China: a meta-analysis

    Science.gov (United States)

    Sun, W.; Li, X.

    2017-12-01

    Upland croplands are the main source of N2O emission. Mitigation of N2O emissions from upland croplands will greatly contribute to an overall reduction of greenhouse gases from agriculture. We performed a meta-analysis to investigate the mitigation options and potential of N2O emissions from wheat and maize fields in China. Results showed that application of inhibitors in wheat and maize fields reduced36‒46% of the N2O emissions with an increase in crop yield. Cutting the application rates of nitrogen fertilizers by no more than 30% could reduce N2O emissions by 10‒18%without crop yield loss. Applications of slow (controlled-) release fertilizer fertilizers and incorporations of crop residues can significantly mitigate N2O emission from wheat fields, but this mitigation is not statistically significant in maize fields. The gross N2O emission could be reduced by 9.3‒13.9Gg N2O-N per wheat season and 10.5‒23.2 Gg N2O-N per maize season when different mitigation options are put into practices. The mitigation potential (MP) in wheat cultivation is particularly notable for Henan, Shandong, Hebei and Anhui Province, contributing 53% to the total MP in wheat fields. Heilongjiang, Jilin, Shandong, Hebei and Henan Province showed high MP in maize cultivation, accounting for approximately 50% of the total MP in maize fields.

  16. Influence of fertilizer nitrogen source and management practice of N2O emissions from two black chernozemic soils

    International Nuclear Information System (INIS)

    Burton, D.L.

    2008-01-01

    Nitrous oxide (N 2 O) is a major anthropogenic greenhouse gas (GHG) emitted by Canadian agricultural systems. Emissions of N 2 O are sporadic, which complicates their accurate quantification as well as the development of adequate management practices. This study was conducted to determine the relative N 2 O production potentials of various nitrogen (N) fertilizer sources and application methods used in cereal production practices in Manitoba. Wheat crops were used to examine variations in N 2 O emissions associated with N formulations applied at the same rate. Treatments included urea surface broadcast in the spring; urea subsurface bands in spring; urea subsurface bands in the fall; anhydrous ammonia subsurface bands in spring and fall; and a control plot where no N was applied. Treatments of polymer-coated urea were also applied. The treatments were established in the fall of 1999. N 2 O fluxes were measured using vented static chambers. Samples were analyzed using gas chromatography. Analysis of variance (ANOVA) was performed in order to obtain cumulative annual N 2 O emissions. Results of the study showed that N 2 O emissions associated with the use of anhydrous ammonia were no greater than emissions associated with urea. Higher N 2 O emissions were observed in fall applications of N fertilizer. The dominant factors controlling differences in N 2 O emissions between sites and years included precipitation, soil water content, and soil texture. 26 refs., 6 tabs

  17. Hot moments of N2O transformation and emission in tropical soils from the Pantanal and the Amazon (Brazil)

    DEFF Research Database (Denmark)

    Liengaard, Lars; Figueiredo, Viviane; Markfoged, Rikke

    2014-01-01

    Tropical wetland soils emit large amounts of nitrous oxide (N2O), especially following wetting of drained soil. We investigated seasonally drained wetland soils from the Pantanal and the Amazon, both with a natural high nitrate content and low pH. Here we report the effect of wetting...... on the production, emission and consumption of N2O on these soils. Intact soil cores were wetted to simulate natural water logging events, and microsensor measurements were used to i) characterize the vertical microscale distribution of O2 and N2O, ii) monitor the accumulation of N2O in the anoxic soil volume...

  18. The diversity of the N2O reducers matters for the N2O:N2 denitrification end-product ratio across an annual and a perennial cropping system.

    Directory of Open Access Journals (Sweden)

    Luiz eDomeignoz-Horta1

    2015-09-01

    Full Text Available Agriculture is the main source of terrestrial emissions of N2O, a potent greenhouse gas and the main cause of ozone layer depletion. The reduction of N2O into N2 by microorganisms carrying the nitrous oxide reductase gene (nosZ is the only biological process known to eliminate this greenhouse gas. Recent studies showed that a previously unknown clade of N2O-reducers was related to the capacity of the soil to act as an N2O sink, opening the way for new strategies to mitigate emissions. Here, we investigated whether the agricultural practices could differently influence the two N2O reducer clades with consequences for denitrification end-products. The abundance of N2O-reducers and producers was quantified by real-time PCR, and the diversity of both nosZ clades was determined by 454 pyrosequencing. Potential N2O production and potential denitrification activity were used to calculate the denitrification gaseous end-product ratio. Overall, the results showed limited differences between management practices but there were significant differences between cropping systems in both the abundance and structure of the nosZII community, as well as in the [rN2O/r(N2O+N2] ratio. More limited differences were observed in the nosZI community, suggesting that the newly identified nosZII clade is more sensitive than nosZI to environmental changes. Potential denitrification activity and potential N2O production were explained mainly by the soil properties while the diversity of the nosZII clade on its own explained 26% of the denitrification end-product ratio, which highlights the importance of understanding the ecology of this newly identified clade of N2O reducers for mitigation strategies.

  19. The diversity of the N2O reducers matters for the N2O:N2 denitrification end-product ratio across an annual and a perennial cropping system.

    Science.gov (United States)

    Domeignoz-Horta, Luiz A; Spor, Aymé; Bru, David; Breuil, Marie-Christine; Bizouard, Florian; Léonard, Joël; Philippot, Laurent

    2015-01-01

    Agriculture is the main source of terrestrial emissions of N2O, a potent greenhouse gas and the main cause of ozone layer depletion. The reduction of N2O into N2 by microorganisms carrying the nitrous oxide reductase gene (nosZ) is the only biological process known to eliminate this greenhouse gas. Recent studies showed that a previously unknown clade of N2O-reducers was related to the capacity of the soil to act as an N2O sink, opening the way for new strategies to mitigate emissions. Here, we investigated whether the agricultural practices could differently influence the two N2O reducer clades with consequences for denitrification end-products. The abundance of N2O-reducers and producers was quantified by real-time PCR, and the diversity of both nosZ clades was determined by 454 pyrosequencing. Potential N2O production and potential denitrification activity were used to calculate the denitrification gaseous end-product ratio. Overall, the results showed limited differences between management practices but there were significant differences between cropping systems in both the abundance and structure of the nosZII community, as well as in the [rN2O/r(N2O+N2)] ratio. More limited differences were observed in the nosZI community, suggesting that the newly identified nosZII clade is more sensitive than nosZI to environmental changes. Potential denitrification activity and potential N2O production were explained mainly by the soil properties while the diversity of the nosZII clade on its own explained 26% of the denitrification end-product ratio, which highlights the importance of understanding the ecology of this newly identified clade of N2O reducers for mitigation strategies.

  20. Inverse modelling of European N2O emissions. Assimilating observations from different networks

    Energy Technology Data Exchange (ETDEWEB)

    Corazza, M.; Bergamaschi, P.; Dentener, F. [European Commission Joint Research Centre, Institute for Environment and Sustainability, 21027 Ispra (Italy); Vermeulen, A.T.; Popa, E. [Energy research Centre of the Netherlands ECN, Petten (Netherlands); Aalto, T. [Finnish Meteorological Institute FMI, Helsinki (Finland); Haszpra, L. [Hungarian Meteorological Service, Budapest (Hungary); Meinhardt, F. [Umweltbundesamt UBA, Messstelle Schauinsland, Kirchzarten (Germany); O' Doherty, S. [School of Chemistry, University of Bristol, Bristol (United Kingdom); Thompson, R. [Laboratoire des Sciences du Climat et de l' Environment LSCE, Gif sur Yvette (France); Moncrieff, J. [Edinburgh University, Edinburgh (United Kingdom); Steinbacher, M. [Swiss Federal Laboratories for Materials Science and Technology Empa, Duebendorf (Switzerland); Jordan, A. [Max Planck Institute for Biogeochemistry, Jena (Germany); Dlugokencky, E. [NOAA Earth System Research Laboratory, Global Monitoring Division, Boulder, CO (United States); Bruehl, C. [Max Planck Institute for Chemistry, Mainz (Germany); Krol, M. [Wageningen University and Research Centre WUR, Wageningen (Netherlands)

    2010-07-01

    We describe the setup and first results of an inverse modelling system for atmospheric N2O, based on a four-dimensional variational (4DVAR) technique and the atmospheric transport zoom model TM5. We focus in this study on the European domain, utilizing a comprehensive set of quasi-continuous measurements over Europe, complemented by N2O measurements from the Earth System Research Laboratory of the National Oceanic and Atmospheric Administration (NOAA/ESRL) cooperative global air sampling network. Despite ongoing measurement comparisons among networks parallel measurements at a limited number of stations show that significant offsets exist among the different laboratories. Since the spatial gradients of N2O mixing ratios are of the same order of magnitude as these biases, the direct use of these biased datasets would lead to significant errors in the derived emissions. Therefore, in order to also use measurements with unknown offsets, a new bias correction scheme has been implemented within the TM5-4DVAR inverse modelling system, thus allowing the simultaneous assimilation of observations from different networks. The N2O bias corrections determined in the TM5-4DVAR system agree within 0.1 ppb (dry-air mole fraction) with the bias derived from the measurements at monitoring stations where parallel NOAA discrete air samples are available. The N2O emissions derived for the northwest European countries for 2006 show good agreement with the bottom-up emission inventories reported to the United Nations Framework Convention on Climate Change (UNFCCC). Moreover, the inverse model can significantly narrow the uncertainty range reported in N2O emission inventories, while the lack of measurements does not allow for better emission estimates in southern Europe. Several sensitivity experiments were performed to test the robustness of the results. It is shown that also inversions without detailed a priori spatio-temporal emission distributions are capable to reproduce major

  1. Characterizing CH4 and N2O Fluxes from a Soybean/Corn Ecosystem in Minnesota

    Science.gov (United States)

    Zhang, X.; Lee, X.; Griffis, T. J.; Baker, J. M.; Erickson, M.; Hu, N.; Xiao, W.

    2009-12-01

    In order to characterize the budgets of three major greenhouse gases (CO2, CH4 and N2O) from cropland, we conducted an experiment near Rosemount, Minnesota, in a landscape dominated by soybean and corn faming. The experiment was carried out at the plant, the ecosystem, and the regional scales. A steady-state flow-through chamber was used to measure the fluxes from the plants of soybean and corn. The gradient diffusion method was used to determine the fluxes at the ecosystem scale. Concentration measurements on a tall tower were used to drive a Lagrangian transport model to interoperate the surface fluxes at the regional scale. Measurements of CH4 and N2O at each scale were made using tunable diode laser spectroscopy. The results to date are summarized as follows: 1) Corn plants were a small net sink of N2O with an average uptake of 4×10-4 µmol m-2 s-1 mainly occurring at night. The N2O flux of unfertilized soybean plants was below the instrument detection limit, and that of fertilized plants was a net source to the atmosphere at a rate of 5×10-3 µmol m-2 s-1 with the emission mainly occurring at night. 2) Both the corn and soybean plants showed a slight uptake of CH4 during the night and release during the day. The daily average CH4 flux was a small net sink for soybean (5×10-5 µmol m-2 s-1 ) and a small net source for corn (1×10-4 µmol m-2 s-1 ). 3) The soybean ecosystem was a source of N2O, with an emission rate of 1×10-4 µmol m-2 s-1 at night and 5×10-4 µmol m-2 s-1 during the day (The analysis of the ecosystem data for corn is under way). 4) The tall tower measurements indicate a strong source of CH4 and N2O at the regional scale. These results will be discussed in the context of a Lagrangian transport model, which is currently under development.

  2. A field robot for autonomous laser-based N2O flux measurements

    Science.gov (United States)

    Molstad, Lars; Reent Köster, Jan; Bakken, Lars; Dörsch, Peter; Lien, Torgrim; Overskeid, Øyvind; Utstumo, Trygve; Løvås, Daniel; Brevik, Anders

    2014-05-01

    N2O measurements in multi-plot field trials are usually carried out by chamber-based manual gas sampling and subsequent laboratory-based gas chromatographic N2O determination. Spatial and temporal resolution of these measurements are commonly limited by available manpower. However, high spatial and temporal variability of N2O fluxes within individual field plots can add large uncertainties to time- and area-integrated flux estimates. Detailed mapping of this variability would improve these estimates, as well as help our understanding of the factors causing N2O emissions. An autonomous field robot was developed to increase the sampling frequency and to operate outside normal working hours. The base of this system was designed as an open platform able to carry versatile instrumentation. It consists of an electrically motorized platform powered by a lithium-ion battery pack, which is capable of autonomous navigation by means of a combined high precision real-time kinematic (RTK) GPS and an inertial measurement unit (IMU) system. On this platform an elevator is mounted, carrying a lateral boom with a static chamber on each side of the robot. Each chamber is equipped with a frame of plastic foam to seal the chamber when lowered onto the ground by the elevator. N2O flux from the soil covered by the two chambers is sequentially determined by circulating air between each chamber and a laser spectrometer (DLT-100, Los Gatos Research, Mountain View, CA, USA), which monitors the increase in N2O concentration. The target enclosure time is 1 - 2 minutes, but may be longer when emissions are low. CO2 concentrations are determined by a CO2/H2O gas analyzer (LI-840A, LI-COR Inc., Lincoln, NE, USA). Air temperature and air pressure inside both chambers are continuously monitored and logged. Wind speed and direction are monitored by a 3D sonic anemometer on top of the elevator boom. This autonomous field robot can operate during day and night time, and its working hours are only

  3. Marine hypoxia/anoxia as a source of CH4 and N2O

    Directory of Open Access Journals (Sweden)

    M. I. Scranton

    2010-07-01

    Full Text Available We review here the available information on methane (CH4 and nitrous oxide (N2O from major marine, mostly coastal, oxygen (O2-deficient zones formed both naturally and as a result of human activities (mainly eutrophication. Concentrations of both gases in subsurface waters are affected by ambient O2 levels to varying degrees. Organic matter supply to seafloor appears to be the primary factor controlling CH4 production in sediments and its supply to (and concentration in overlying waters, with bottom-water O2-deficiency exerting only a modulating effect. High (micromolar level CH4 accumulation occurs in anoxic (sulphidic waters of silled basins, such as the Black Sea and Cariaco Basin, and over the highly productive Namibian shelf. In other regions experiencing various degrees of O2-deficiency (hypoxia to anoxia, CH4 concentrations vary from a few to hundreds of nanomolar levels. Since coastal O2-deficient zones are generally very productive and are sometimes located close to river mouths and submarine hydrocarbon seeps, it is difficult to differentiate any O2-deficiency-induced enhancement from in situ production of CH4 in the water column and its inputs through freshwater runoff or seepage from sediments. While the role of bottom-water O2-deficiency in CH4 formation appears to be secondary, even when CH4 accumulates in O2-deficient subsurface waters, methanotrophic activity severely restricts its diffusive efflux to the atmosphere. As a result, an intensification or expansion of coastal O2-deficient zones will probably not drastically change the present status where emission from the ocean as a whole forms an insignificant term in the atmospheric CH4 budget. The situation is different for N2O, the production of which is greatly enhanced in low-O2 waters, and although it is lost through denitrification in most suboxic and anoxic environments, the peripheries of such environments offer most suitable conditions for its production, with the

  4. The riverine source of CH4 and N2O from the Republic of Congo, western Congo Basin

    Science.gov (United States)

    Upstill-Goddard, Robert C.; Salter, Matthew E.; Mann, Paul J.; Barnes, Jonathan; Poulsen, John; Dinga, Bienvenu; Fiske, Gregory J.; Holmes, Robert M.

    2017-05-01

    We discuss concentrations of dissolved CH4, N2O, O2, NO3- and NH4+, and emission fluxes of CH4 and N2O for river sites in the western Congo Basin, Republic of Congo (ROC). Savannah, swamp forest and tropical forest samples were collected from the Congo main stem and seven of its tributaries during November 2010 (41 samples; wet season) and August 2011 (25 samples; dry season; CH4 and N2O only). Dissolved inorganic nitrogen (DIN: NH4++ NO3-; wet season) was dominated by NO3- (63 ± 19 % of DIN). Total DIN concentrations (1.5-45.3 µmol L-1) were consistent with the near absence of agricultural, domestic and industrial sources for all three land types. Dissolved O2 (wet season) was mostly undersaturated in swamp forest (36 ± 29 %) and tropical forest (77 ± 36 %) rivers but predominantly supersaturated in savannah rivers (100 ± 17 %). The dissolved concentrations of CH4 and N2O were within the range of values reported earlier for sub-Saharan African rivers. Dissolved CH4 was found to be supersaturated (11.2-9553 nmol L-1; 440-354 444 %), whereas N2O ranged from strong undersaturation to supersaturation (3.2-20.6 nmol L-1; 47-205 %). Evidently, rivers of the ROC are persistent local sources of CH4 and can be minor sources or sinks for N2O. During the dry season the mean and range of CH4 and N2O concentrations were quite similar for the three land types. Wet and dry season mean concentrations and ranges were not significant for N2O for any land type or for CH4 in savannah rivers. The latter observation is consistent with seasonal buffering of river discharge by an underlying sandstone aquifer. Significantly higher wet season CH4 concentrations in swamp and forest rivers suggest that CH4 can be derived from floating macrophytes during flooding and/or enhanced methanogenesis in adjacent flooded soils. Swamp rivers also exhibited both low (47 %) and high (205 %) N2O saturation but wet season values were overall significantly lower than in either tropical forest or

  5. An automated setup to measure paleoatmospheric δ13C-CH4, δ15N-N2O and δ18O-N2O in one ice core sample

    NARCIS (Netherlands)

    Sperlich, P.; Buizert, C.; Jenk, T.M.; Sapart, C.J.|info:eu-repo/dai/nl/31400596X; Prokopiou, M.|info:eu-repo/dai/nl/330866117; Röckmann, T.|info:eu-repo/dai/nl/304838233; Blunier, T.

    2013-01-01

    Air bubbles in ice core samples represent the only opportunity to study the isotopic variability of paleoatmospheric CH4 and N2O. The highest possible precision in isotope measurements is required to maximize the resolving power for CH4 and N2O sink and source reconstructions. We present a new setup

  6. Challenges encountered when expanding activated sludge models: a case study based on N2O production

    DEFF Research Database (Denmark)

    Snip, Laura; Boiocchi, Riccardo; Flores Alsina, Xavier

    2014-01-01

    It is common practice in wastewater engineering to extend standard activated sludge models (ASMs) with extra process equations derived from batch experiments. However, such experiments have often been performed under conditions different from the ones normally found in wastewater treatment plants......-scale activated sludge plant. Finally, the simulation results show large differences in oxygen uptake rates, nitritation rates and consequently the quantity of N2O emission (G(N2O)) using the different models......It is common practice in wastewater engineering to extend standard activated sludge models (ASMs) with extra process equations derived from batch experiments. However, such experiments have often been performed under conditions different from the ones normally found in wastewater treatment plants...

  7. Progress in the analysis and interpretation of N2O isotopes: Potential and future challenges

    Science.gov (United States)

    Mohn, Joachim; Tuzson, Béla; Zellweger, Christoph; Harris, Eliza; Ibraim, Erkan; Yu, Longfei; Emmenegger, Lukas

    2017-04-01

    In recent years, research on nitrous oxide (N2O) stable isotopes has significantly advanced, addressing an increasing number of research questions in biogeochemical and atmospheric sciences [1]. An important milestone was the development of quantum cascade laser based spectroscopic devices [2], which are inherently specific for structural isomers (15N14N16O vs. 14N15N16O) and capable to collect real-time data with high temporal resolution, complementary to the well-established isotope-ratio mass-spectrometry (IRMS) method. In combination with automated preconcentration, optical isotope ratio spectroscopy (OIRS) has been applied to disentangle source processes in suburban, rural and pristine environments [e.g. 3, 4]. Within the European Metrology Research Programme (EMRP) ENV52 project "Metrology for high-impact greenhouse gases (HIGHGAS)", the quality of N2O stable isotope analysis by OIRS, the comparability between laboratories, and the traceability to the international isotope ratio scales have been addressed. An inter-laboratory comparison between eleven IRMS and OIRS laboratories, organised within HIGHGAS, indicated limited comparability for 15N site preference, i.e. the difference between 15N abundance in central (N*NO) and end (*NNO) position [5]. In addition, the accuracy of the NH4NO3 decomposition reaction, which provides the link between 15N site preference and the international 15N/14N scale, was found to be limited by non-quantitative NH4NO3 decomposition in combination with substantially different isotope enrichment factors for both nitrogen atoms [6]. Results of the HIGHGAS project indicate that the following research tasks have to be completed to foster research on N2O isotopes: 1) develop improved techniques to link the 15N and 18O abundance and the 15N site preference in N2O to the international stable isotope ratio scales; 2) provide N2O reference materials, pure and diluted in an air matrix, to improve inter-laboratory compatibility. These tasks

  8. Ozone production and losses in N2/O2 mixtures in an ozone generator

    Science.gov (United States)

    Mankelevich, Yu. A.; Poroykov, A. Yu.; Rakhimova, T. V.; Voloshin, D. G.; Chukalovskii, A. A.; Zosimov, A. V.; Lunin, V. V.; Samoilovich, V. G.

    2016-09-01

    Nonunique ozone concentrations at the output of an ozone generator under identical external conditions of barrier discharge activation of N2/O2 mixtures but with different prehistories of operating practice and employed gas mixtures are investigated theoretically. An analytical approach is developed to determine the ozone yield with regard for its heterogeneous loss. Plasma-chemical and electron kinetics in the N2/O2-mixtures are calculated numerically. The results of numerical calculations are compared to experimental data obtained by the authors. It is noted that the heterogeneous loss of ozone is the probable reason for the observed variety of behavior of O3 concentrations, depending on prehistory of ozone generator operation, along with the N2 and O2 gas flow rates and the specific active power.

  9. The different effects of applying fresh, composted or charred manure on soil N2O emissions

    DEFF Research Database (Denmark)

    Zhu, Kun; Christel, Wibke; Bruun, Sander

    2014-01-01

    water potential, homogeneous or heterogeneous distribution of amendments in soil) was evaluated in this study. The mitigation potential of the combined application of charred manure with other amendments was also investigated. The application of fresh or composted manure solids was observed to have much...... with composted manure, N2O emissions were significantly reduced by 41% at pF 2.0, but the mitigation effect of charred manure was not observed at lower soil water potentials....... after soil application. A laboratory study was conducted over a period of 100 days to investigate the N2O emissions from arable soil amended with different manure-derived fertilisers: fresh, composted and charred solid fraction of pig manure. The importance of several factors (fertiliser type, soil...

  10. Manure distribution as a predictor of N2O emissions from soil

    DEFF Research Database (Denmark)

    Petersen, Søren O.; Baral, Khagendra Raj; Arthur, Emmanuel

    2016-01-01

    of manure constituents after field application in a systematic way. Key to predicting the fate of labile carbon (C) and nitrogen (N) in manure is to acknowledge that the liquid phase, and a corresponding fraction of labile C and N, is partly absorbed by the bulk soil in response to the water potential......) adjusted to three soil water potentials (–3, –5 and –10 kPa) and amended with surface-applied pig slurry, cattle slurry, digestate or water only, in total 24 treatments. Net emissions of N2O corresponded to between 0.18% and 0.64% of manure N. Experimental results were analysed with a conceptual model...... of short-term N2O emissions from manure-amended soil, which estimates redistribution of manure constituents and predicts emissions from three sources, i.e. nitrification in bulk soil, and nitrification and denitrification in manure hotspots. Adopting a recent modification, oxygen availability in manure...

  11. Potassium-doped Co3O4 catalyst for direct decomposition of N2O

    International Nuclear Information System (INIS)

    Asano, Kimihiro; Ohnishi, Chie; Iwamoto, Shinji; Inoue, Masashi; Shioya, Yasushi

    2008-01-01

    Direct decomposition of nitrous oxide (N 2 O) on K-doped Co 3 O 4 catalysts was examined. The K-doped Co 3 O 4 catalyst showed a high activity even in the presence of water. In the durability test of the K-doped Co 3 O 4 catalyst, the activity was maintained at least for 12 h. It was found that the activity of the K-doped Co 3 O 4 catalyst strongly depended on the amount of K in the catalyst. In order to reveal the role of the K component on the catalytic activity, the catalyst was characterized by XRD, XPS, TPR and TPD. The results suggested that regeneration of the Co 2+ species from the Co 3+ species formed by oxidation of Co 2+ with the oxygen atoms formed by N 2 O decomposition was promoted by the addition of K to the Co 3 O 4 catalyst. (author)

  12. Separation of N2O and CO2 using room-temperature ionic liquid [bmim][BF4].

    Science.gov (United States)

    Shiflett, Mark B; Niehaus, Anne Marie S; Yokozeki, A

    2011-04-07

    We have developed a ternary equation of state (EOS) model for the N(2)O/CO(2)/1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]) system in order to understand separation of these gases using room-temperature ionic liquids (RTILs). The present model is based on a generic RK (Redlich-Kwong) EOS, with empirical interaction parameters for each binary system. The interaction parameters have been determined using our measured VLE (vapor-liquid equilibrium) data for N(2)O/[bmim][BF(4)] and CO(2)/[bmim][BF(4)] and literature data for N(2)O/CO(2). The binary EOS models for the N(2)O/[bmim][BF(4)] and CO(2)/[bmim][BF(4)] systems correctly predicted the liquid-liquid phase separation found in VLLE experiments. The validity of the ternary EOS model has been checked by conducting VLE experiments for the N(2)O/CO(2)/[bmim][BF(4)] system over a range in temperature from 296 to 315 K. With this EOS model, solubility (VLE) behavior has been calculated for various (T, P, and feed compositions) conditions. For both large and small N(2)O/CO(2) feed ratios, the N(2)O/CO(2) gas selectivity [α(N(2)O/CO(2)) = (y(N(2)O)/x(N(2)O))/(y(CO(2))/x(CO(2)))] is α = 1.4-1.5, compared with (α = 0.96-0.98) in the absence of ionic liquid. While the concentration of the ionic liquid does not affect the selectivity, the addition of an ionic liquid provides the only practical means of separating CO(2) and N(2)O.

  13. High temperature performance and stability of Fe-FER catalyst for N2O decomposition

    Czech Academy of Sciences Publication Activity Database

    Sádovská, Galina; Tabor, Edyta; Sazama, Petr; Lhotka, M.; Bernauer, M.; Sobalík, Zdeněk

    2017-01-01

    Roč. 89, JAN 2017 (2017), s. 133-137 ISSN 1566-7367 R&D Projects: GA ČR(CZ) GA14-10251S; GA MŠk(CZ) LM2015073 Institutional support: RVO:61388955 Keywords : High temperature N2O decomposition * FER * Iron Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 3.330, year: 2016

  14. [The ozone layer and its modification by N2O and inhalation anesthetics].

    Science.gov (United States)

    Radke, J; Fabian, P

    1991-08-01

    As a result of human activities the ozone layer in the stratosphere, which is necessary for life on earth, has changed. The main causes of ozone destruction are chlorofluorcarbons (CFCs) 11 and 12. Recently, caring anesthetists have wondered if and to what degree N2O and popular potent inhalation anesthetics may also contribute to ozone loss. Having consulted the literature, we attempt to answer that question. The ozone-destroying N2O is chiefly produced by burning fossil elements and nitrogenous fertilizing used in agriculture; the share of medically used N2O lies below 2%. Halothane, enflurane, and isoflurane are halogenated anesthetics that contain ozone-destroying halogens (bromine, chlorine, fluorine) to different extents. Complicated experimental calculations for these volatile anesthetics result in a potential for ozone destruction of 0.36 for halothane and 0.02 for enflurane and isoflurane if the potential for ozone destruction by CFCs is set at 1.0. The lifespan of the inhalation anesthetics in the troposphere is with less than 3 years, dramatically less than that of CFCs (70-140 years). The two most important CFCs, 11 and 12, are considered to be currently produced in a quantity of about 800,000 tons per year. On the other hand, the worldwide production of inhalation anesthetics is said to be only 2,000 tons. In view of the experimental calculations and the low worldwide production, the small greenhouse effect, the shorter lifespan in the troposphere, and the low potential for ozone destruction, the negative effects of medically used N2O and inhalation anesthetics on the ozone layer seem negligible. All in all, the inhalation anesthetics are considered to be responsible for only 0.0005% of the ozone destruction at present.

  15. K‑Doped Co−Mn−Al Mixed Oxide Catalyst for N2O Abatement from\

    Czech Academy of Sciences Publication Activity Database

    Pacultová, K.; Karásková, K.; Kovanda, F.; Jirátová, Květa; Šrámek, J.; Kustrovski, P.; Kotarba, A.; Chromčáková, Ž.; Kočí, K.; Obalová, L.

    2016-01-01

    Roč. 55, č. 26 (2016), s. 7076-7084 ISSN 0888-5885 R&D Projects: GA ČR GA14-13750S; GA TA ČR TA01020336 Institutional support: RVO:67985858 Keywords : Co-Mn-Al mixed oxide * N2O decomposition * HNO3 pilot plant Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.843, year: 2016

  16. Role of active oxygen and NOx species in N2O decomposition over Fe-ferrierite

    Czech Academy of Sciences Publication Activity Database

    Sobalík, Zdeněk; Tabor, Edyta; Nováková, Jana; Sathu, Naveen Kumar; Závěta, K.

    2012-01-01

    Roč. 289, MAY 2012 (2012), s. 164-170 ISSN 0021-9517 R&D Projects: GA AV ČR KAN100400702; GA ČR GA203/09/1627; GA ČR GAP106/11/0624 Institutional research plan: CEZ:AV0Z40400503 Keywords : N2O decomposition * iron ferrierite * active oxygen Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.787, year: 2012

  17. Photocatalytic Decomposition of N2O on Ag-TiO2

    Czech Academy of Sciences Publication Activity Database

    Kočí, K.; Krejčíková, Simona; Šolcová, Olga; Obalová, L.

    2012-01-01

    Roč. 191, č. 1 (2012), s. 134-137 ISSN 0920-5861. [International Symposium on Nitrogen Oxides Emission Abatement. Zakopane, 04.09.2011-07.09.2011] R&D Projects: GA ČR GA104/09/0694 Institutional support: RVO:67985858 Keywords : photocatalytic decomposition * N2O * Ag doping * TiO2 Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.980, year: 2012

  18. Novel method for online monitoring of dissolved N2O concentrations through a gas stripping device.

    Science.gov (United States)

    Mampaey, Kris E; van Dongen, Udo G J M; van Loosdrecht, Mark C M; Volcke, Eveline I P

    2015-01-01

    Nitrous oxide emissions from wastewater treatment plants are currently measured by online gas phase analysis or grab sampling from the liquid phase. In this study, a novel method is presented to monitor the liquid phase N2O concentration for aerated as well as non-aerated conditions/reactors, following variations both in time and in space. The monitoring method consists of a gas stripping device, of which the measurement principle is based on a continuous flow of reactor liquid through a stripping flask and subsequent analysis of the N2O concentration in the stripped gas phase. The method was theoretically and experimentally evaluated for its fit for use in the wastewater treatment context. Besides, the influence of design and operating variables on the performance of the gas stripping device was addressed. This method can easily be integrated with online off-gas measurements and allows to better investigate the origin of the gas emissions from the treatment plant. Liquid phase measurements of N2O are of use in mitigation of these emissions. The method can also be applied to measure other dissolved gasses, such as methane, being another important greenhouse gas.

  19. Laser flash-photolysis and gas discharge in N2O-containing mixture: kinetic mechanism

    Science.gov (United States)

    Kosarev, Ilya; Popov, Nikolay; Starikovskaia, Svetlana; Starikovskiy, Andrey; mipt Team

    2011-10-01

    The paper is devoted to further experimental and theoretical analysis of ignition by ArF laser flash-photolysis and nanosecond discharge in N2O-containing mixture has been done. Additional experiments have been made to assure that laser emission is distributed uniformly throughout the cross-section. The series of experiments was proposed and carried out to check validity of O(1D) determination in experiments on plasma assisted ignition initiated by flash-photolysis. In these experiments, ozone density in the given mixture (mixture composition and kinetics has been preliminary analyzed) was measured using UV light absorption in Hartley band. Good coincidence between experimental data and results of calculations have been obtained Temporal behavior of energy input, electric field and electric current has been measured and analyzed. These data are considered as initial conditions for numerical modeling of the discharge in O2:N2O:H2:Ar = 0.3:1:3:5 mixture. Ion-molecular reactions and reactions of active species production in Ar:H2:O2:N2O mixture were analyzed. The set of reactions to describe chemical transformation in the system due to the discharge action has been selected.

  20. Laboratory and field studies on a new sensor for dissolved N2O.

    Science.gov (United States)

    Thaler, Klemens M; Niessner, Reinhard; Haisch, Christoph

    2017-08-01

    Nitrous oxide (N 2 O) is a strong greenhouse gas, whose atmospheric concentration has been continuously increasing for more than 200 years. One major source is wastewater treatment plants (WWTPs), where N 2 O emissions should either be minimized or pushed to levels where exploitation in biogas combustion engines becomes efficient. Both these strategies require online control of the N 2 O concentrations in the liquid as well as in the gas phase. For this purpose, we propose a system for membrane extraction of the gas from the liquid phase, which then allows for a subsequent gas-phase analysis, which we perform by photoacoustic spectroscopy. We compare different theoretical calculations of the extraction efficiency, based either on a straightforward mathematical model or on a finite element simulation. The comparison of results with measurements produced on a well-defined model system shows good accordance. Based on the outcome, a field probe was developed and tested on a WWTP, yielding results comparable to the one achieved by GC reference analysis. Graphical abstract Gas extraction from liquids, e.g. from a wastewater treatment plant, for online gas monitoring.

  1. Crafting biochars to reduce N2O and CO2 emissions while also improving soil quality

    Science.gov (United States)

    Novak, Jeff; Ippolito, Jim; Spokas, Kurt; Sigua, Gilbert; Kammann, Claudia; Wrage-Monnig, Nicole; Borchard, Nils; Schirrmann, Michael; Estavillo, Jose Maria; Fuertes-Mendizabal, Teresa; Menendez, Sergio; Cayuela, Maria Luz

    2017-04-01

    Biochar used as an amendment has been linked to nitrous oxide (N2O) emission reductions, a decrease in nitrogen (N) leaching, and soil quality improvements (e.g., soil carbon sequestration, pH, etc.). While numerous articles will support these three facts, conversely, there are reports of no to marginal influences. One reason for the mixed biochar performance could be related to applying biochar with incorrect chemical and physical characteristics. As a means to increase biochar efficiency, we introduced the concept of crafting biochars with properties attuned to specific soil deficiencies. Implementing this concept requires a literature review to identify salient biochar characteristics that reduces N2O emissions, impacts N availability, while also improving soil quality. Thus, scientists from the USDA-ARS and through a coalition of European scientists under the FACCE-JPI umbrella have conceived the DesignChar4food (d4f) project. In this project, scientists are working collaboratively to further this concept to match the appropriate biochar for selective soil quality improvement, retain N for crops, and promote greenhouse gas reductions. This presentation will highlight results from the d4f team compromising a meta-analysis of articles on biochar:N2O dynamics, N availability, and how designer biochars can target specific soil quality improvements.

  2. The effect of ultralow-dose antibiotics exposure on soil nitrate and N2O flux

    Science.gov (United States)

    Devries, Stephanie L.; Loving, Madeline; Li, Xiqing; Zhang, Pengfei

    2015-11-01

    Exposure to sub-inhibitory concentrations of antibiotics has been shown to alter the metabolic activity of micro-organisms, but the impact on soil denitrification and N2O production has rarely been reported. In this study, incubation and column transport experiments were conducted on soils exposed to as many as four antibiotics in the ng·kg-1 range (several orders of magnitude below typical exposure rates) to evaluate the impact of ultralow dose exposure on net nitrate losses and soil N2O flux over time. Under anaerobic incubation conditions, three antibiotics produced statistically significant dose response curves in which denitrification was stimulated at some doses and inhibited at others. Sulfamethoxazole in particular had a stimulatory effect at ultralow doses, an effect also evidenced by a near 17% increase in nitrate removal during column transport. Narasin also showed evidence of stimulating denitrification in anaerobic soils within 3 days of exposure, which is concurrent to a statistically significant increase in N2O flux measured over moist soils exposed to similar doses. The observation that even ultralow levels of residual antibiotics may significantly alter the biogeochemical cycle of nitrogen in soil raises a number of concerns pertaining to agriculture, management of nitrogen pollution, and climate change, and warrants additional investigations.

  3. Mitigation potential of soil carbon management overestimated by neglecting N2O emissions

    Science.gov (United States)

    Lugato, Emanuele; Leip, Adrian; Jones, Arwyn

    2018-02-01

    International initiatives such as the `4 per 1000' are promoting enhanced carbon (C) sequestration in agricultural soils as a way to mitigate greenhouse gas emissions1. However, changes in soil organic C turnover feed back into the nitrogen (N) cycle2, meaning that variation in soil nitrous oxide (N2O) emissions may offset or enhance C sequestration actions3. Here we use a biogeochemistry model on approximately 8,000 soil sampling locations in the European Union4 to quantify the net CO2 equivalent (CO2e) fluxes associated with representative C-mitigating agricultural practices. Practices based on integrated crop residue retention and lower soil disturbance are found to not increase N2O emissions as long as C accumulation continues (until around 2040), thereafter leading to a moderate C sequestration offset mostly below 47% by 2100. The introduction of N-fixing cover crops allowed higher C accumulation over the initial 20 years, but this gain was progressively offset by higher N2O emissions over time. By 2060, around half of the sites became a net source of greenhouse gases. We conclude that significant CO2 mitigation can be achieved in the initial 20-30 years of any C management scheme, but after that N inputs should be controlled through appropriate management.

  4. Wastes Management Can Minimize CH4 and N2O Emissions from Wetlands in Indonesia

    Directory of Open Access Journals (Sweden)

    Abdul Hadi

    2015-07-01

    Full Text Available Paddy (Oriza sativa L. and Oil palm (Elaeis guineensis Jack are two important crops and are potential to produce wastes which may lead to huge greenhouse gas emissions if they are not managed properly.  Open burning and conventional composting are commonly practiced by farmers and/or planters to managed agricultural wastes in Indonesia.  A series of research has been carried out  to elucidate (1 the reductions of CH4 and N2O due to incertion of a catalitic converter on burning kiln, (2 the best composting technique of oil palm field wastes, and (3 the effects of oil palm field wastes compost application in oil palm fields and of paddy field wastes biochar in integrated oil palm-paddy fields.  The results showed that CH4 and N2O emissions from paddy field wastes (i.e., rice straw or rice husk was lower than that from oil palm empty fruit bunch (EFB.  Furthermore, insertion of a catalytic converter into pyrolysis installation reduced the CO2, CH4 and N2O emissions from paddy field wastes as much as 14.5, 17.8 and 11.1%, respectively.  Incorporation of EFB compost did not increase greenhouse gas emission from oil palm fields. These results suggest that biochar and EFB compost can be practiced to manage agricultural wastes in Indonesia.

  5. Catalytic decomposition of N2O over CeO2 supported Co3O4 catalysts

    Indian Academy of Sciences (India)

    Abstract. This work was aimed to design efficient catalysts for N2O decomposition at low temperatures. Cobalt oxide (Co3O4) was prepared by hydrothermal, precipitation and combustion methods and tested for. N2O decomposition. It was found that the catalysts prepared by solution combustion synthesis were most active.

  6. Evaluation of the Agronomic Impacts on Yield-Scaled N2O Emission from Wheat and Maize Fields in China

    Directory of Open Access Journals (Sweden)

    Wenling Gao

    2017-07-01

    Full Text Available Contemporary crop production faces dual challenges of increasing crop yield while simultaneously reducing greenhouse gas emission. An integrated evaluation of the mitigation potential of yield-scaled nitrous oxide (N2O emission by adjusting cropping practices can benefit the innovation of climate smart cropping. This study conducted a meta-analysis to assess the impact of cropping systems and soil management practices on area- and yield-scaled N2O emissions during wheat and maize growing seasons in China. Results showed that the yield-scaled N2O emissions of winter wheat-upland crops rotation and single spring maize systems were respectively 64.6% and 40.2% lower than that of winter wheat-rice and summer maize-upland crops rotation systems. Compared to conventional N fertilizer, application of nitrification inhibitors and controlled-release fertilizers significantly decreased yield-scaled N2O emission by 41.7% and 22.0%, respectively. Crop straw returning showed no significant impacts on area- and yield-scaled N2O emissions. The effect of manure on yield-scaled N2O emission highly depended on its application mode. No tillage significantly increased the yield-scaled N2O emission as compared to conventional tillage. The above findings demonstrate that there is great potential to increase wheat and maize yields with lower N2O emissions through innovative cropping technique in China.

  7. Emissions of N2O from fertilized and grazed grassland on organic soil in relation to groundwater level

    NARCIS (Netherlands)

    Beek, C.L.; Pleijter, M.; Jacobs, C.M.J.; Velthof, G.L.; Groenigen, van J.W.; Kuikman, P.J.

    2010-01-01

    Intensively managed grasslands on organic soils are a major source of nitrous oxide (N2O) emissions. The Intergovernmental Panel on Climate Change (IPCC) therefore has set the default emission factor at 8 kg N–N2O ha-1 year-1 for cultivation and management of organic soils. Also, the Dutch national

  8. Do plant species influence soil CO2 and N2O fluxes in a diverse tropical forest?

    Science.gov (United States)

    van Haren, Joost L. M.; de Oliveira, R. Cosme; Restrepo-Coupe, Natalia; Hutyra, Lucy; de Camargo, Plinio B.; Keller, Michael; Saleska, Scott R.

    2010-09-01

    To test whether plant species influence greenhouse gas production in diverse ecosystems, we measured wet season soil CO2 and N2O fluxes close to ˜300 large (>35 cm in diameter at breast height (DBH)) trees of 15 species at three clay-rich forest sites in central Amazonia. We found that soil CO2 fluxes were 38% higher near large trees than at control sites >10 m away from any tree (P Caryocar villosum, Lecythis lurida, Schefflera morototoni, and Manilkara huberi were 84%-196% greater than Erisma uncinatum and Vochysia maxima, both Vochysiaceae. Tree species identity was the most important explanatory factor for N2O fluxes, accounting for more than twice the N2O flux variability as all other factors combined. Two observations suggest a mechanism for this finding: (1) sugar addition increased N2O fluxes near C. villosum twice as much (P < 0.05) as near Vochysiaceae and (2) species mean N2O fluxes were strongly negatively correlated with tree growth rate (P = 0.002). These observations imply that through enhanced belowground carbon allocation liana and tree species can stimulate soil CO2 and N2O fluxes (by enhancing denitrification when carbon limits microbial metabolism). Alternatively, low N2O fluxes potentially result from strong competition of tree species with microbes for nutrients. Species-specific patterns in CO2 and N2O fluxes demonstrate that plant species can influence soil biogeochemical processes in a diverse tropical forest.

  9. Solubility and Diffusivity Data for the Absorption of COS, CO2, and N2O in Amine Solutions

    NARCIS (Netherlands)

    Littel, Rob J.; Versteeg, Geert F.; Swaaij, Wlm P.M. van

    1992-01-01

    Absorption data for COS and N2O in aqueous solutions of N-methyldiethanolamine (MDEA), ethylene glycol, and sulfolane (tetrahydrothiophene 1,1-dioxide) at 298 K and solubility data for COS in water at temperatures ranging from 298 to 338 K are presented. Also density, viscosity, N2O solubility, and

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

    Science.gov (United States)

    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. The molar H: Corg ratio of biochar is a key factor in mitigating N2O emissions from soil

    NARCIS (Netherlands)

    Cayuela, M.L.; Jeffery, S.L.; Zwieten, van L.

    2015-01-01

    A previously published meta-analysis of biochar impacts on soil N2O emissions by Cayuela et al. (2014) found a “grand mean” reduction in N2O emissions of 54 ± 6% following biochar application to soil. Here we update this analysis to include 26 additional manuscripts bringing the total to 56

  12. Optimal estimation of regional N2O emissions using a three-dimensional global model

    Science.gov (United States)

    Huang, J.; Golombek, A.; Prinn, R.

    2004-12-01

    In this study, we use the MATCH (Model of Atmospheric Transport and Chemistry) model and Kalman filtering techniques to optimally estimate N2O emissions from seven source regions around the globe. The MATCH model was used with NCEP assimilated winds at T62 resolution (192 longitude by 94 latitude surface grid, and 28 vertical levels) from July 1st 1996 to December 31st 2000. The average concentrations of N2O in the lowest four layers of the model were then compared with the monthly mean observations from six national/global networks (AGAGE, CMDL (HATS), CMDL (CCGG), CSIRO, CSIR and NIES), at 48 surface sites. A 12-month-running-mean smoother was applied to both the model results and the observations, due to the fact that the model was not able to reproduce the very small observed seasonal variations. The Kalman filter was then used to solve for the time-averaged regional emissions of N2O for January 1st 1997 to June 30th 2000. The inversions assume that the model stratospheric destruction rates, which lead to a global N2O lifetime of 130 years, are correct. It also assumes normalized emission spatial distributions from each region based on previous studies. We conclude that the global N2O emission flux is about 16.2 TgN/yr, with {34.9±1.7%} from South America and Africa, {34.6±1.5%} from South Asia, {13.9±1.5%} from China/Japan/South East Asia, {8.0±1.9%} from all oceans, {6.4±1.1%} from North America and North and West Asia, {2.6±0.4%} from Europe, and {0.9±0.7%} from New Zealand and Australia. The errors here include the measurement standard deviation, calibration differences among the six groups, grid volume/measurement site mis-match errors estimated from the model, and a procedure to account approximately for the modeling errors.

  13. New estimates of direct N2O emissions from Chinese croplands from 1980 to 2007 using localized emission factors

    Directory of Open Access Journals (Sweden)

    F. S. Zhang

    2011-10-01

    Full Text Available Nitrous oxide (N2O is a long-lived greenhouse gas with a large radiation intensity and it is emitted mainly from agricultural land. Accurate estimates of total direct N2O emissions from croplands on a country scale are important for global budgets of anthropogenic sources of N2O emissions and for the development of effective mitigation strategies. The objectives of this study were to re-estimate direct N2O emissions using localized emission factors and a database of measurements from Chinese croplands. We obtained N2O emission factors for paddy fields (0.41 ± 0.04% and uplands (1.05 ± 0.02% from a normalization process through cube root transformation of the original data. After comparing the results of normalization from the original values, Logarithmic and cube root transformations were used because the frequency of the original data was not normally distributed. Direct N2O emissions from Chinese croplands from 1980 to 2007 were estimated using IPCC (2006 guidelines combined with separate localized emission factors for paddy fields and upland areas. Direct N2O emissions from paddy fields showed little change, increasing by 10.5% with an annual rate of increase of 0.4% from 32.3 Gg N2O-N in 1980 to 35.7 Gg N2O-N in 2007. In contrast, emissions from uplands changed dramatically, increasing by 308% with an annual rate of 11% from 68.0 Gg N2O-N in 1980 to 278 Gg N2O-N in 2007. Total direct N2O emissions from Chinese croplands increased by 213% with an annual rate of 7.6% from 100 Gg N2O-N in 1980 to 313 Gg N2O-N in 2007, and were determined mainly by upland emissions (accounting for 67.8–88.6% of total emissions from 1980 to 2007. Synthetic N fertilizers played a major role in N2O emissions from agricultural land, and the magnitude of the contributions to total direct N2O emissions made by different amendments was synthetic N fertilizer > manure > straw, representing about 78, 15, and 6% of total direct N2O emissions, respectively, between

  14. Effects of flooding cycles in the Pantanal on the turnover of soil nitrogen pools and emission of N2O

    Science.gov (United States)

    Liengaard, L.; Nielsen, L. P.; Revsbech, N. P.; Elberling, B.; Priemé, A.; Prast, A. E.; Kühl, M.

    2011-06-01

    The global nitrous oxide (N2O) budget remains unbalanced. Currently, ~25 % of the global N2O emission is ascribed to uncultivated tropical soils, but the exact locations and controlling mechanisms are not clear. In this study, we present the first detailed study of the dynamics of soil nitrogen pools and flux of N2O from the world's largest wetland Pantanal, South America. At three long-term measurement sites we measured porewater pH, NO3-, NH4+ , N2O and O2 as well as N2O dynamics in soil slurry, and in situ fluxes of N2O and CO2. The pool of inorganic nitrogen changed (7.1-92 μg NH4+-N g dw-1, and 0.1-201 μg NO3--N g dw-1) with the seasonal flooding and drying cycles, indicating dynamic shifts between ammonification, nitrification and denitrification. In the field, O2 penetrated to a depth of 60 cm in dry soil, but O2 was rapidly depleted in response to precipitation. Soil pH fluctuated from pH 7-7.5 in flooded soil to pH 3.5-4.5 in the same drained soil. Microsensor measurements showed rapid N2O accumulation reaching >500-1000 Pa in soil slurries due to incomplete denitrification. In situ fluxes of N2O were comparable to heavily fertilized forest or agricultural soils. The dominating parameter affecting N2O emission rate was precipitation inducing peak emissions of >3 mmol N2O m-2 d-1, while the mean daily flux was 0.43 mmol N2O m-2 d-1. Single measurement based screening of in situ activity at 10 Pantanal sites during dry conditions averaged 0.39 mmol N2O m-2 d-1. The in situ N2O fluxes were only weakly correlated (r2 = 0.177) with NO3- and pH value, showing a tendency (p = 0.063) for NO3- concentration to be positively correlated with the in situ N2O flux and a weaker tendency (p = 0.138) for the pH value to be negatively correlated with the in situ N2O flux. Over 170 days of the drained period we estimated non-wetted drained soil to contribute 70.0 mmol N2O m-2, while rain induced peak events contributed 9.2 mmol N2O m-2, resulting in a total N2O emission

  15. The Regulation of CH4 and N2O fluxes by Wetlands at Landscape Level

    Science.gov (United States)

    Soosaar, K.; Maddison, M.; Salm, J. O.; Järveoja, J.; Hansen, R.; Mander, Ü.

    2012-04-01

    The world's wetlands, despite being only about 5% of the terrestrial landscape, are currently significant net sinks of more than 1 Pg yr-1 of carbon (Mitsch et al 2012). At landscape level wetlands and riparian zones are important regulators of nutrient transport (Zedler 2003). However, they can be also significant hot spots of greenhouse gas (GHG) emissions (Teiter&Mander 2005). Swedish experience shows that the nationally planned wetland creation (12,000 ha) could make a significant contribution to the targeted reduction of N fluxes (up to 27% of the Swedish environmental objective), at an environmental risk equalling 0.04% of the national anthropogenic GHG emission (Thiere et al 2011). Only few studies consider the potential GHG emission throughout both natural and created wetlands. The main objective of this study was to clarify the potential of various wetland ecosystem and riparian zones of northern rural landscapes in regulation of GHG emissions. Monthly-based measurements of GHG emissions using closed chamber method were performed from October 2007 to October 2011 in 47 study sites in Estonia. The study sites cover various wetlands and riparian forests as well as reference areas on automorphic soils. In general, wetlands' drainage was the most significant disturbance factor influencing GHG fluxes, causing significant increase of N2O emission as well as decreasing CH4 emission. However, we also observed significantly high CH4 flux from drained peatlands. In most of the soils with ground/soil water levels deeper than 30 cm from the surface, a significant decrease of CH4 fluxes were detected. The highest CH4 emissions (up to 5060 kg CH4-C ha-1 yr-1) were detected from drained fen grasslands. In the case of N2O, no clear differences were found between colder and warmer periods. Relatively higher N2O fluxes were measured from the drained fen grassland, the fertilized arable land, the riparian forest on automorphic soil, and the drained transition fen forest

  16. Using stable isotopes to follow excreta N dynamics and N2O emissions in animal production systems.

    Science.gov (United States)

    Clough, T J; Müller, C; Laughlin, R J

    2013-06-01

    Nitrous oxide (N2O) is a potent greenhouse gas and the dominant anthropogenic stratospheric ozone-depleting emission. The tropospheric concentration of N2O continues to increase, with animal production systems constituting the largest anthropogenic source. Stable isotopes of nitrogen (N) provide tools for constraining emission sources and, following the temporal dynamics of N2O, providing additional insight and unequivocal proof of N2O source, production pathways and consumption. The potential for using stable isotopes of N is underutilised. The intent of this article is to provide an overview of what these tools are and demonstrate where and how these tools could be applied to advance the mitigation of N2O emissions from animal production systems. Nitrogen inputs and outputs are dominated by fertiliser and excreta, respectively, both of which are substrates for N2O production. These substrates can be labelled with 15N to enable the substrate-N to be traced and linked to N2O emissions. Thus, the effects of changes to animal production systems to reduce feed-N wastage by animals and fertiliser wastage, aimed at N2O mitigation and/or improved animal or economic performance, can be traced. Further 15N-tracer studies are required to fully understand the dynamics and N2O fluxes associated with excreta, and the biological contribution to these fluxes. These data are also essential for the new generation of 15N models. Recent technique developments in isotopomer science along with stable isotope probing using multiple isotopes also offer exciting capability for addressing the N2O mitigation quest.

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

    Science.gov (United States)

    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.

  18. N2O5 uptake coefficients and nocturnal NO2 removal rates determined from ambient wintertime measurements

    Science.gov (United States)

    Wagner, N. L.; Riedel, T. P.; Young, C. J.; Bahreini, R.; Brock, C. A.; Dubé, W. P.; Kim, S.; Middlebrook, A. M.; Öztürk, F.; Roberts, J. M.; Russo, R.; Sive, B.; Swarthout, R.; Thornton, J. A.; VandenBoer, T. C.; Zhou, Y.; Brown, S. S.

    2013-08-01

    Heterogeneous N2O5 uptake onto aerosol is the primary nocturnal path for removal of NOx (= NO + NO2) from the atmosphere and can also result in halogen activation through production of ClNO2. The N2O5 uptake coefficient has been the subject of numerous laboratory studies; however, only a few studies have determined the uptake coefficient from ambient measurements, and none has been focused on winter conditions, when the portion of NOx removed by N2O5 uptake is the largest. In this work, N2O5 uptake coefficients are determined from ambient wintertime measurements of N2O5 and related species at the Boulder Atmospheric Observatory in Weld County, CO, a location that is highly impacted by urban pollution from Denver, as well as emissions from agricultural activities and oil and gas extraction. A box model is used to analyze the nocturnal nitrate radical chemistry and predict the N2O5 concentration. The uptake coefficient in the model is iterated until the predicted N2O5 concentration matches the measured concentration. The results suggest that during winter, the most important influence that might suppress N2O5 uptake is aerosol nitrate but that this effect does not suppress uptake coefficients enough to limit the rate of NOx loss through N2O5 hydrolysis. N2O5 hydrolysis was found to dominate the nocturnal chemistry during this study consuming 80% of nocturnal gas phase nitrate radical production. Typically, less than 15% of the total nitrate radical production remained in the form of nocturnal species at sunrise when they are photolyzed and reform NO2.

  19. Reacto-Diffusive Length of N2O5 in Aqueous Sulfate- and Chloride-Containing Aerosol Particles.

    Science.gov (United States)

    Gaston, Cassandra J; Thornton, Joel A

    2016-02-25

    Heterogeneous reactions of dinitrogen pentoxide (N2O5) on aerosol particles impact air quality and climate, yet aspects of the relevant physical chemistry remain unresolved. One important consideration is the competing effects of diffusion and the rate of chemical reaction within the particle, which determines the length that N2O5 travels within a particle before reacting, referred to as the reacto-diffusive length (l). Large values of l imply a dependence of the reactive uptake efficiency of N2O5, i.e., γ(N2O5), on particle size. We present measurements of the size dependence of γ(N2O5) on aqueous sodium chloride, ammonium sulfate, and ammonium bisulfate particles. γ(N2O5) on ammonium sulfate and ammonium bisulfate particles ranged from 0.016 ± 0.005 to 0.036 ± 0.001 as the surface-area-weighted particle radius increased from 39 to 127 nm, resulting in an estimated l of 32 ± 6 nm. In contrast, γ(N2O5) on sodium chloride particles was independent of particle size, suggesting a near-surface reaction dominated the uptake of N2O5. Differences in the reactivity of the N2O5 intermediate, NO2(+), with water and chloride can explain the observed dependencies. These results allow for parameterizations in atmospheric models to determine a more robust population mean value of γ(N2O5) that accounts for the distribution of particle sizes.

  20. Modelling the effect of aggregates on N2O emission from denitrification in an agricultural peat soil

    Directory of Open Access Journals (Sweden)

    P. Kabat

    2011-09-01

    Full Text Available Nitrous oxide (N2O emissions are highly variable in time, with high peak emissions lasting a few days to several weeks and low background emissions. This temporal variability is poorly understood which hampers the simulation of daily N2O emissions. In structured soils, like clay and peat, aggregates hamper the diffusion of oxygen, which leads to anaerobic microsites in the soil, favourable for denitrification. Diffusion of N2O out of the aggregates is also hampered, which leads to delayed emissions and increased reduction of N2O to N2. In this model simulation study we investigate the effect of aggregates in soils on the N2O emissions. We present a parameterization to simulate the effects of aggregates on N2O production by denitrification and on N2O reduction. The parameterization is based on the mobile-immobile model concept. It was implemented in a field-scale hydrological-biogeochemical model combination. We compared the simulated fluxes with observed fluxes from a fertilized and drained peat soil under grass. The results of this study show that aggregates strongly affect the simulated N2O emissions: peak emissions are lower, whereas the background emissions are slightly higher. Including the effect of aggregates caused a 40% decrease in the simulated annual emissions relative to the simulations without accounting for the effects of aggregates. The new parameterization significantly improved the model performance regarding simulation of observed daily N2O fluxes; r2 and RMSE improved from 0.11 and 198 g N2O-N ha−1 d−1 to 0.41 and 40 g N2O-N ha−1 d−1, respectively. Our analyses of the model results show that aggregates have a larger impact on the reduction than on the production of N2O. Reduction of N2O is more sensitive to changes in the drivers than production of N2O and is in that sense the key to understanding N2O emissions from denitrification. The effects of changing environmental conditions on reduction of N2O relative to N2O

  1. Projections of oceanic N2O emissions in the 21st century using the IPSL Earth system model

    Science.gov (United States)

    Martinez-Rey, J.; Bopp, L.; Gehlen, M.; Tagliabue, A.; Gruber, N.

    2015-07-01

    The ocean is a substantial source of nitrous oxide (N2O) to the atmosphere, but little is known about how this flux might change in the future. Here, we investigate the potential evolution of marine N2O emissions in the 21st century in response to anthropogenic climate change using the global ocean biogeochemical model NEMO-PISCES. Assuming nitrification as the dominant N2O formation pathway, we implemented two different parameterizations of N2O production which differ primarily under low-oxygen (O2) conditions. When forced with output from a climate model simulation run under the business-as-usual high-CO2 concentration scenario (RCP8.5), our simulations suggest a decrease of 4 to 12 % in N2O emissions from 2005 to 2100, i.e., a reduction from 4.03/3.71 to 3.54/3.56 TgN yr-1 depending on the parameterization. The emissions decrease strongly in the western basins of the Pacific and Atlantic oceans, while they tend to increase above the oxygen minimum zones (OMZs), i.e., in the eastern tropical Pacific and in the northern Indian Ocean. The reduction in N2O emissions is caused on the one hand by weakened nitrification as a consequence of reduced primary and export production, and on the other hand by stronger vertical stratification, which reduces the transport of N2O from the ocean interior to the ocean surface. The higher emissions over the OMZ are linked to an expansion of these zones under global warming, which leads to increased N2O production, associated primarily with denitrification. While there are many uncertainties in the relative contribution and changes in the N2O production pathways, the increasing storage seems unequivocal and determines largely the decrease in N2O emissions in the future. From the perspective of a global climate system, the averaged feedback strength associated with the projected decrease in oceanic N2O emissions amounts to around -0.009 W m-2 K-1, which is comparable to the potential increase from terrestrial N2O sources. However

  2. Characterization and production and consumption processes of N2O emitted from temperate agricultural soils determined via isotopomer ratio analysis

    Science.gov (United States)

    Toyoda, Sakae; Yano, Midori; Nishimura, Sei-Ichi; Akiyama, Hiroko; Hayakawa, Atsushi; Koba, Keisuke; Sudo, Shigeto; Yagi, Kazuyuki; Makabe, Akiko; Tobari, Yoshifumi; Ogawa, Nanako O.; Ohkouchi, Naohiko; Yamada, Keita; Yoshida, Naohiro

    2011-06-01

    Isotopomer ratios of N2O (bulk nitrogen and oxygen isotope ratios, δ15Nbulk and δ18O, and intramolecular 15N site preference, SP) are useful parameters that characterize sources of this greenhouse gas and also provide insight into production and consumption mechanisms. We measured isotopomer ratios of N2O emitted from typical Japanese agricultural soils (Fluvisols and Andisols) planted with rice, wheat, soybean, and vegetables, and treated with synthetic (urea or ammonium) and organic (poultry manure) fertilizers. The results were analyzed using a previously reported isotopomeric N2O signature produced by nitrifying/denitrifying bacteria and a characteristic relationship between δ15Nbulk and SP during N2O reduction by denitrifying bacteria. Relative contributions from nitrification (hydroxylamine oxidation) and denitrification (nitrite reduction) to gross N2O production deduced from the analysis depended on soil type and fertilizer. The contribution from nitrification was relatively high (40%-70%) in Andisols amended with synthetic ammonium fertilizer, while denitrification was dominant (50%-90%) in the same soils amended with poultry manure during the period when N2O production occurred in the surface layer. This information on production processes is in accordance with that obtained from flux/concentration analysis of N2O and soil inorganic nitrogen. However, isotopomer analysis further revealed that partial reduction of N2O was pronounced in high-bulk density, alluvial soil (Fluvisol) compared to low-bulk density, volcanic ash soil (Andisol), and that the observed difference in N2O flux between normal and pelleted manure could have resulted from a similar mechanism with different rates of gross production and gross consumption. The isotopomeric analysis is based on data from pure culture bacteria and would be improved by further studies on in situ biological processes in soils including those by fungi. When flux/concentration-weighted average isotopomer

  3. Effects of land-use history, fertilization, and precipitation on short-term N2O emissions from agricultural soils using open-path eddy flux N2O and static chamber methods.

    Science.gov (United States)

    Gelfand, I.; Cui, M.; Tao, L.; Sun, K.; Tang, J.; Zondlo, M. A.; Robertson, G. P.

    2012-12-01

    Nitrous oxide (N2O) is an important greenhouse gas with an atmospheric lifetime of ~ 120 years and a global warming potential ~300 times that of CO2. Atmospheric N2O concentrations have increased from ~270 ppbv during pre-industrial times to ~330 ppbv today. Anthropic emissions are a major source of atmospheric N2O and about half of global anthropic emissions are from the agricultural sector. N2Oemissions from soils exhibit high spatial and temporal variability. Estimation of N2O emissions from agricultural soils is particularly challenging because N2O fluxes are affected by fertilizer type and application rates, land-use history and management, as well as soil biological activity. We studied ecosystem level N2O emissions from agricultural lands using a combination of static chamber methods and continuous N2O exchange measured by a quantum cascade laser-based, open-path analyzer coupled with an eddy-covariance system. We also compared N2O emissions between different static chamber methods, using both laboratory-based gas chromatography (GC) and an in situ quantum cascade (QC) laser for N2O analyses. Finally, we compared emissions estimated by the two static chamber methods to those estimated by eddy-covariance. We examined pre- and post- fertilization N2O fluxes from soils in two no-till continuous corn fields with distinct land-use histories: one field converted from permanent grassland (CRP-C) and the other from conventional corn-soybean rotation (AGR-C). Both fields were fertilized with ~160 kg urea-N ha-1. We compared N2O emissions from these fields to those from an unmanaged grassland (REF). In addition, we examined the potential effect of post-fertilization precipitation on N2O emissions by applying 50 mm of artificial rainfall to the static chambers at all three locations. Measurements of N2O emissions using both GC and QC laser methods with static chambers were in good agreement (R2 = 0.96). Even though average soil N2O fluxes before fertilization were low

  4. Minimizing N2O emissions and carbon footprint on a full-scale activated sludge sequencing batch reactor.

    Science.gov (United States)

    Rodriguez-Caballero, A; Aymerich, I; Marques, Ricardo; Poch, M; Pijuan, M

    2015-03-15

    A continuous, on-line quantification of the nitrous oxide (N2O) emissions from a full-scale sequencing batch reactor (SBR) placed in a municipal wastewater treatment plant (WWTP) was performed in this study. In general, N2O emissions from the biological wastewater treatment system were 97.1 ± 6.9 g N2O-N/Kg [Formula: see text] consumed or 6.8% of the influent [Formula: see text] load. In the WWTP of this study, N2O emissions accounted for over 60% of the total carbon footprint of the facility, on average. Different cycle configurations were implemented in the SBR aiming at reaching acceptable effluent values. Each cycle configuration consisted of sequences of aerated and non-aerated phases of different time length being controlled by the ammonium set-point fixed. Cycles with long aerated phases showed the largest N2O emissions, with the consequent increase in carbon footprint. Cycle configurations with intermittent aeration (aerated phases up to 20-30 min followed by short anoxic phases) were proven to effectively reduce N2O emissions, without compromising nitrification performance or increasing electricity consumption. This is the first study in which a successful operational strategy for N2O mitigation is identified at full-scale. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Mitigation of soil N2O emission by inoculation with a mixed culture of indigenous Bradyrhizobium diazoefficiens

    Science.gov (United States)

    Akiyama, Hiroko; Hoshino, Yuko Takada; Itakura, Manabu; Shimomura, Yumi; Wang, Yong; Yamamoto, Akinori; Tago, Kanako; Nakajima, Yasuhiro; Minamisawa, Kiwamu; Hayatsu, Masahito

    2016-09-01

    Agricultural soil is the largest source of nitrous oxide (N2O), a greenhouse gas. Soybean is an important leguminous crop worldwide. Soybean hosts symbiotic nitrogen-fixing soil bacteria (rhizobia) in root nodules. In soybean ecosystems, N2O emissions often increase during decomposition of the root nodules. Our previous study showed that N2O reductase can be used to mitigate N2O emission from soybean fields during nodule decomposition by inoculation with nosZ++ strains [mutants with increased N2O reductase (N2OR) activity] of Bradyrhizobium diazoefficiens. Here, we show that N2O emission can be reduced at the field scale by inoculation with a mixed culture of indigenous nosZ+ strains of B. diazoefficiens USDA110 group isolated from Japanese agricultural fields. Our results also suggested that nodule nitrogen is the main source of N2O production during nodule decomposition. Isolating nosZ+ strains from local soybean fields would be more applicable and feasible for many soybean-producing countries than generating mutants.

  6. An improved N2O-method for measuring Cu-dispersion

    DEFF Research Database (Denmark)

    Jensen, Joakim R.; Johannessen, Tue; Livbjerg, Hans

    2004-01-01

    The paper presents an improved approach for the measurement of Cu-dispersion in catalysts using the oxidation of the Cu surface atoms by N2O. During a single easy-to-perform experiment, the degree of surface and bulk oxidation of copper can be separated due to a continuous measurement of evolved N...... by the He carrier gas. By the new experimental procedure we can separate the two parts of the N-2-signal, i.e. a rapid surface oxidation and a slow solid state diffusion-limited bulk oxidation. As a result, we can - based on a mathematical correction for the influence of diffusion-make a more accurate...

  7. Cobalt Oxide Catalysts on Commercial Supports for N2O Decomposition.

    Czech Academy of Sciences Publication Activity Database

    Klegová, A.; Pacultová, K.; Fridrichová, D.; Volodarskaja, A.; Kovanda, J.; Jirátová, Květa

    2017-01-01

    Roč. 40, č. 5 (2017), s. 981-990 ISSN 0930-7516. [International Congress of Chemical and Process Engineering CHISA 2016 /22./and the 19th Conference PRES 2016. Prague, 27.08.2016-31.08.2016] R&D Projects: GA ČR GA14-13750S Institutional support: RVO:67985858 Keywords : N2O decomposition * cobalt oxide * shaped catalyst Subject RIV: CI - Industrial Chemistry, Chemical Engineering OBOR OECD: Chemical process engineering Impact factor: 2.051, year: 2016

  8. Marine hypoxia/anoxia as a source of CH4 and N2O

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Bange, H.W.; Farias, L.; Monteiro, P.M.S.; Scranton, M.I.; Zhang, J.

    the key control on biological cycling of these gases in the ocean is the redox state of the environment, which is determined by the ambient oxygen (O2) concentration. Con- taining carbon in its most reduced (−4) form, CH4 is pro- duced in significant... as the O2 con- centrations fall below about 0.5 ml l−1 (∼22 µM) (Goreau et al., 1980). Thus, changes in O2 distribution may alter source strengths of CH4 and N2O. Such changes in subsurface O2 field may be forced by altered circulation/stratification in re...

  9. Micrometeorological measurements over 3 years reveal differences in N2 O emissions between annual and perennial crops.

    Science.gov (United States)

    Abalos, Diego; Brown, Shannon E; Vanderzaag, Andrew C; Gordon, Robert J; Dunfield, Kari E; Wagner-Riddle, Claudia

    2016-03-01

    Perennial crops can deliver a wide range of ecosystem services compared to annual crops. Some of these benefits are achieved by lengthening the growing season, which increases the period of crop water and nutrient uptake, pointing to a potential role for perennial systems to mitigate soil nitrous oxide (N2 O) emissions. Employing a micrometeorological method, we tested this hypothesis in a 3-year field experiment with a perennial grass-legume mixture and an annual corn monoculture. Given that N2 O emissions are strongly dependent on the method of fertilizer application, two manure application options commonly used by farmers for each crop were studied: injection vs. broadcast application for the perennial; fall vs. spring application for the annual. Across the 3 years, lower N2 O emissions (P crop, even though annual N2 O emissions increased tenfold for the perennial after ploughing. The percentage of N2 O lost per unit of fertilizer applied was 3.7, 3.1 and 1.3 times higher for the annual for each consecutive year. Differences in soil organic matter due to the contrasting root systems of these crops are probably a major factor behind the N2 O reduction. We found that a specific manure management practice can lead to increases or reductions in annual N2 O emissions depending on environmental variables. The number of freeze-thaw cycles during winter and the amount of rainfall after fertilization in spring were key factors. Therefore, general manure management recommendations should be avoided because interannual weather variability has the potential to determine if a specific practice is beneficial or detrimental. The lower N2 O emissions of perennial crops deserve further research attention and must be considered in future land-use decisions. Increasing the proportion of perennial crops in agricultural landscapes may provide an overlooked opportunity to regulate N2 O emissions. © 2015 John Wiley & Sons Ltd.

  10. Climate, duration, and N placement determine N2 O emissions in reduced tillage systems: a meta-analysis.

    Science.gov (United States)

    van Kessel, Chris; Venterea, Rodney; Six, Johan; Adviento-Borbe, Maria Arlene; Linquist, Bruce; van Groenigen, Kees Jan

    2013-01-01

    No-tillage and reduced tillage (NT/RT) management practices are being promoted in agroecosystems to reduce erosion, sequester additional soil C and reduce production costs. The impact of NT/RT on N2 O emissions, however, has been variable with both increases and decreases in emissions reported. Herein, we quantitatively synthesize studies on the short- and long-term impact of NT/RT on N2 O emissions in humid and dry climatic zones with emissions expressed on both an area- and crop yield-scaled basis. A meta-analysis was conducted on 239 direct comparisons between conventional tillage (CT) and NT/RT. In contrast to earlier studies, averaged across all comparisons, NT/RT did not alter N2 O emissions compared with CT. However, NT/RT significantly reduced N2 O emissions in experiments >10 years, especially in dry climates. No significant correlation was found between soil texture and the effect of NT/RT on N2 O emissions. When fertilizer-N was placed at ≥5 cm depth, NT/RT significantly reduced area-scaled N2 O emissions, in particular under humid climatic conditions. Compared to CT under dry climatic conditions, yield-scaled N2 O increased significantly (57%) when NT/RT was implemented <10 years, but decreased significantly (27%) after ≥10 years of NT/RT. There was a significant decrease in yield-scaled N2 O emissions in humid climates when fertilizer-N was placed at ≥5 cm depth. Therefore, in humid climates, deep placement of fertilizer-N is recommended when implementing NT/RT. In addition, NT/RT practices need to be sustained for a prolonged time, particularly in dry climates, to become an effective mitigation strategy for reducing N2 O emissions. © 2012 Blackwell Publishing Ltd.

  11. Continuous Eddy Covariance Measurements of N2O Emissions and Controls from an Intensively Grazed Dairy Farm

    Science.gov (United States)

    Schipper, L. A.; Liang, L. L.; Wall, A.; Campbell, D.

    2017-12-01

    New Zealand's greenhouse gas (GHG) inventory is disproportionally dominated by methane and nitrous oxide which account for 54% of emissions. These GHGs are derived from pastoral agriculture that supports dairying and meat production. To date, most studies on quantifying or mitigating agricultural N2O emissions have used flux chamber measurements. Recent advances in detector technology now means that routine field-to-farm scale measurements of N2O emissions might be possible using the eddy covariance technique. In late 2016, we established an eddy covariance tower that measured N2O emissions from a dairy farm under year-round grazing. An Aerodyne quantum cascade laser (QCL) was used to measure N2O, CH4 and H2O concentration at 10 Hz and housed in a weatherproof and insulated enclosure (0.9 m ´ 1.2 m) and powered by mains power (240 VAC). The enclosure maintained a stable setpoint temperature (30±0.2°C) by using underground cooling pipes, fans and recirculating instrument heat. QCL (true 10 Hz digital) and CSAT3B sonic anemometer high frequency data are aligned using Network Time Protocol and EddyPro covariance maximisation during flux processing. Fluxes generally integrated over about 6-8 ha. Stable summertime baseline N2O fluxes (FN2O) were around 12-24 g N2O-N ha-1 d-1 (0.5-1.0 nmol N2O m-2 s-1). Grazing by cows during dry summer resulted in only modest increases in FN2O to 24-48 g N2O-N ha-1 d-1 (1.0-2.0 nmol N2O m-2 s-1). However, the first rain events after grazing resulted in large, short-lived (1-3 days) FN2O pulses reaching peaks of 144-192 g N2O-N ha-1 d-1 (6-8 nmol N2O m-2 s-1). During these elevated N2O emissions, FN2O displayed a significant diurnal signal, with peak fluxes mid-afternoon which was best explained by variation in shallow soil temperature in summer. In winter (both cooler and wetter) FN2O were not as easily explained on a daily basis but were generally greater than summer. Throughout the year, FN2O was strongly dependent on water filled

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

    Science.gov (United States)

    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

  13. Reducing N2O and NO emissions while sustaining crop productivity in a Chinese vegetable-cereal double cropping system.

    Science.gov (United States)

    Yao, Zhisheng; Yan, Guangxuan; Zheng, Xunhua; Wang, Rui; Liu, Chunyan; Butterbach-Bahl, Klaus

    2017-12-01

    High nitrogen (N) inputs in Chinese vegetable and cereal productions played key roles in increasing crop yields. However, emissions of the potent greenhouse gas nitrous oxide (N 2 O) and atmospheric pollutant nitric oxide (NO) increased too. For lowering the environmental costs of crop production, it is essential to optimize N strategies to maintain high crop productivity, while reducing the associated N losses. We performed a 2 year-round field study regarding the effect of different combinations of poultry manure and chemical N fertilizers on crop yields, N use efficiency (NUE) and N 2 O and NO fluxes from a Welsh onion-winter wheat system in the North China Plain. Annual N 2 O and NO emissions averaged 1.14-3.82 kg N ha -1 yr -1 (or 5.54-13.06 g N kg -1 N uptake) and 0.57-1.87 kg N ha -1 yr -1 (or 2.78-6.38 g N kg -1 N uptake) over all treatments, respectively. Both N 2 O and NO emissions increased linearly with increasing total N inputs, and the mean annual direct emission factors (EF d ) were 0.39% for N 2 O and 0.19% for NO. Interestingly, the EF d for chemical N fertilizers (N 2 O: 0.42-0.48%; NO: 0.07-0.11%) was significantly lower than for manure N (N 2 O: 1.35%; NO: 0.76%). Besides, a negative power relationship between yield-scaled N 2 O, NO or N 2 O + NO emissions and NUE was observed, suggesting that improving NUE in crop production is crucial for increasing crop yields while decreasing nitrogenous gas release. Compared to the current farmers' fertilization rate, alternative practices with reduced chemical N fertilizers increased NUE and decreased annual N 2 O + NO emissions substantially, while crop yields remained unaffected. As a result, annual yield-scaled N 2 O + NO emissions were reduced by > 20%. Our study shows that a reduction of current application rates of chemical N fertilizers by 30-50% does not affect crop productivity, while at the same time N 2 O and NO emissions would be reduced significantly. Copyright © 2017 Elsevier Ltd. All rights

  14. N2O emissions from the global agricultural nitrogen cycle – current state and future scenarios

    Directory of Open Access Journals (Sweden)

    H. Lotze-Campen

    2012-10-01

    Full Text Available Reactive nitrogen (Nr is not only an important nutrient for plant growth, thereby safeguarding human alimentation, but it also heavily disturbs natural systems. To mitigate air, land, aquatic, and atmospheric pollution caused by the excessive availability of Nr, it is crucial to understand the long-term development of the global agricultural Nr cycle. For our analysis, we combine a material flow model with a land-use optimization model. In a first step we estimate the state of the Nr cycle in 1995. In a second step we create four scenarios for the 21st century in line with the SRES storylines. Our results indicate that in 1995 only half of the Nr applied to croplands was incorporated into plant biomass. Moreover, less than 10 per cent of all Nr in cropland plant biomass and grazed pasture was consumed by humans. In our scenarios a strong surge of the Nr cycle occurs in the first half of the 21st century, even in the environmentally oriented scenarios. Nitrous oxide (N2O emissions rise from 3 Tg N2O-N in 1995 to 7–9 in 2045 and 5–12 Tg in 2095. Reinforced Nr pollution mitigation efforts are therefore required.

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

    Science.gov (United States)

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

    2013-07-01

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

  16. Challenges encountered when expanding activated sludge models: a case study based on N2O production.

    Science.gov (United States)

    Snip, L J P; Boiocchi, R; Flores-Alsina, X; Jeppsson, U; Gernaey, K V

    2014-01-01

    It is common practice in wastewater engineering to extend standard activated sludge models (ASMs) with extra process equations derived from batch experiments. However, such experiments have often been performed under conditions different from the ones normally found in wastewater treatment plants (WWTPs). As a consequence, these experiments might not be representative for full-scale performance, and unexpected behaviour may be observed when simulating WWTP models using the derived process equations. In this paper we want to highlight problems encountered using a simplified case study: a modified version of the Activated Sludge Model No. 1 (ASM1) is upgraded with nitrous oxide (N2O) formation by ammonia-oxidizing bacteria. Four different model structures have been implemented in the Benchmark Simulation Model No. 1 (BSM1). The results of the investigations revealed two typical difficulties: problems related to the overall mathematical model structure and problems related to the published set of parameter values. The paper describes the model implementation incompatibilities, the variability in parameter values and the difficulties of reaching similar conditions when simulating a full-scale activated sludge plant. Finally, the simulation results show large differences in oxygen uptake rates, nitritation rates and consequently the quantity of N2O emission (GN2O) using the different models.

  17. Photocatalytic decomposition of N2O over g-C3N4/WO3photocatalysts.

    Science.gov (United States)

    Reli, Martin; Svoboda, Ladislav; Šihor, Marcel; Troppová, Ivana; Pavlovský, Jiří; Praus, Petr; Kočí, Kamila

    2017-11-24

    Although the nitrous oxide belongs among three of the most contributing greenhouse gases to global warming, it is quite neglected by photocatalytic society. The g-C 3 N 4 and WO 3 composites were therefore tested for the photocatalytic decomposition of N 2 O for the first time. The pure photocatalysts were prepared by simple calcination of precursors, and the composites were prepared by mixing of suspension of pure components in water followed by calcination. The structural (X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy), textural (N 2 physisorption), and optical properties (diffuse reflectance spectroscopy, photoluminescence spectroscopy, photoelectrochemical measurements) of all composites were correlated with photocatalytic activity. The experimental results and results from characterization techniques confirmed creation of Z-scheme in the WO 3 /g-C 3 N 4 composites, which was confirmed by hydroxyl radicals' trapping measurements. The photocatalytic decomposition of N 2 O was carried out in the presence of UVA light (peak intensity at 365 nm) and the 1:2 WO 3 /g-C 3 N 4 composite was the most active one, but the photocatalytic activity was just negligibly higher than that of pure WO 3 . This is caused by relatively weak interaction between WO 3 and g-C 3 N 4 which was revealed from XPS.

  18. Inventories of N2O and NO emissions from European forest soils

    DEFF Research Database (Denmark)

    Kesik, M.; Ambus, Per; Baritz, R.

    2005-01-01

    .9 kt N yr(-1) for N2O, for year 2000 meteorology. The results show that process-oriented models coupled to a GIS are useful tools for the calculation of regional, national, or global inventories of biogenic N trace gas emissions from soils. This work represents the most comprehensive effort to date...... and emission of N trace gases. This model was validated against field observations of N trace gas fluxes from 19 sites obtained within the EU project NOFRETETE, and shown to perform well for N2O (r(2) = 0.68, slope = 0.76) and NO (r(2) = 0.78, slope = 0.73). For the calculation of a European-wide emission...... vary substantial from year to year and that distinct regional patterns can be observed. Our central estimate of NO emissions from forest soils in the EU amounts to 98.4, 84.9 and 99.2 kt N yr(-1) 1, using meteorology from 1990, 1995 and year 2000, respectively. This is emissions...

  19. Studies on nitrogen oxides (NOx and N2O) in pressurized fluidized bed combustion

    International Nuclear Information System (INIS)

    Lu Yong

    1998-01-01

    This thesis describes the experimental studies of nitrogen oxide (NO, NO 2 , N 2 O) emissions in pressurized fluidized bed combustion (PFBC). In the first part of the thesis the background and the objectives of this study are introduced. The second part summarizes the fundamental knowledge about the formation and destruction of nitrogen oxides in coal combustion, particularly in the conditions of PFBC. The instrumentation of test facilities, measurement and data analysis is described in the third part. Then the most important experimental results follow in the next parts. The forth part describes the results from a PFBC test rig and an empirical modelling for predicting the emissions of NO x and N 2 O. Finally, the fundamental work on coal combustion and fuel nitrogen conversion in a PFBC batch reactor is presented. These studies clearly confirm the potential of PFBC technology in the control nitrogen of oxide emissions. The research in the test rig was concentrated on determining the effects of process parameters on the emissions of nitrogen oxides with different fuels. Another objective was to examine the reduction of nitrogen oxides with the control methods in PFBC conditions, including ammonia injection and air staging combustion for reducing NO, and high temperature operations for reducing N 2 0. The results indicate that pressurized operation suppresses the conversion of fuel-N to nitrogen oxides and favors with employing the reduction methods for further nitrogen oxide reduction, for instance the temperature window of NO reduction with ammonia injection has been found to be widened to even lower temperature range. Maximum reductions of 80-85 % with ammonia injection and 75-80 % with air staging combustion were achieved in the conditions examined. Considerably low emissions of N 2 O ( 2 O control, and thermal decomposition proved to be the laming pathway of N 2 O destruction in PFBC. In the examined pressure range, increasing pressure causes a decrease of NO

  20. Top-down estimates of European CH4 and N2O emissions based on 5 different inverse models

    Energy Technology Data Exchange (ETDEWEB)

    Bergamaschi, P.; Corazza, M.; Segers, A. [EC Joint Research Centre JRC, Institute for Environment and Sustainability IES, Ispra (Italy); Vermeulen, A. [Energy research Centre of the Netherlands ECN, Petten (Netherlands); Manning, A.; Athanassiadou, M. [Met Office Exeter, Devon (United Kingdom); Thompson, R.; Pison, I.; Bousquet, P. [Laboratoire des Sciences du Climat et de l' Environment LSCE, Gif sur Yvette (France); Karstens, U. [Max-Planck-Institute for Biogeochemistry, Jena (Germany)

    2011-04-15

    Atmospheric measurements combined with inverse atmospheric models can provide independent top-down estimates of greenhouse gas (GHG) emissions. This is important in particular for N2O and CH4, for which considerable uncertainties of the bottom-up inventories exist (uncertainty estimates of bottom-up emissions reported to UNFCCC: CH4: {approx}30%; N2O >100% for annual country totals). According to UNFCCC inventories, CH4 and N2O contributed 'only' {approx}8% and {approx}7%, respectively, of total GHG emissions of EU-15 countries (2007). However, the reported reductions of total GHG emissions (1990-2007: -199 Tg CO2 eq) are mainly attributed to CH4 (-133 Tg CO2 eq) and N2O (-105 Tg CO2 eq)

  1. Effects of Different Vegetation Zones on CH4 and N2O Emissions in Coastal Wetlands: A Model Case Study

    Directory of Open Access Journals (Sweden)

    Yuhong Liu

    2014-01-01

    Full Text Available The coastal wetland ecosystems are important in the global carbon and nitrogen cycle and global climate change. For higher fragility of coastal wetlands induced by human activities, the roles of coastal wetland ecosystems in CH4 and N2O emissions are becoming more important. This study used a DNDC model to simulate current and future CH4 and N2O emissions of coastal wetlands in four sites along the latitude in China. The simulation results showed that different vegetation zones, including bare beach, Spartina beach, and Phragmites beach, produced different emissions of CH4 and N2O in the same latitude region. Correlation analysis indicated that vegetation types, water level, temperature, and soil organic carbon content are the main factors affecting emissions of CH4 and N2O in coastal wetlands.

  2. Production and mitigation of N2O in sequentially membrane-aerated redox-stratified nitritation/anammox biofilms

    DEFF Research Database (Denmark)

    Smets, Barth F.; Pellicer i Nàcher, Carles; Thamdrup, Bo

    batch incubations with biofilm samples revealed a significant N2O assimilatory activity. Anoxic incubations with N-15 enriched nitrite, nitrate, or ammonium, in presence or absence of acetate revealed the following: a very high conversion of original nitrite or nitrate N to N2O over N2, no stimulatory......Combining partial nitritation with anaerobic ammonium oxidation maybe a cost- and energy-efficient alternative to remove reduced nitrogen from nitrogen rich waste streams. However, increased N2O emissions (upto several % of the incoming N flux) have been observed for reactors performing partial...... nitritation, which is likely due to the stimulatory effect of combined elevated nitrite and ammonium concentrations and reduced oxygen concentrations on nitrous oxide formation by ammonium oxidizing bacteria. Because increased N2O emission may be inherent to partial nitrification systems, we have explored how...

  3. Parameterization of N2O5 Reaction Probabilities on the Surface of Particles Containing Ammonium, Sulfate, and Nitrate

    Science.gov (United States)

    A comprehensive parameterization was developed for the heterogeneous reaction probability (γ) of N2O5 as a function of temperature, relative humidity, particle composition, and phase state, for use in advanced air quality models. The reaction probabilities o...

  4. Modeling the Formation of N2O and NO2 in the Thermal De-NOx Process

    DEFF Research Database (Denmark)

    Miller, James A.; Glarborg, Peter

    1996-01-01

    A chemical kinetic model is formulated that satisfactorily predicts the NO removed and the N2O and NO2 produced by the Thermal De-NOx process over a wide range of temperatures and initial oxygen concentrations....

  5. N2O-producing microorganisms in the gut of the earthworm Aporrectodea caliginosa are indicative of ingested soil bacteria.

    Science.gov (United States)

    Ihssen, Julian; Horn, Marcus A; Matthies, Carola; Gössner, Anita; Schramm, Andreas; Drake, Harold L

    2003-03-01

    The main objectives of this study were (i) to determine if gut wall-associated microorganisms are responsible for the capacity of earthworms to emit nitrous oxide (N(2)O) and (ii) to characterize the N(2)O-producing bacteria of the earthworm gut. The production of N(2)O in the gut of garden soil earthworms (Aporrectodea caliginosa) was mostly associated with the gut contents rather than the gut wall. Under anoxic conditions, nitrite and N(2)O were transient products when supplemental nitrate was reduced to N(2) by gut content homogenates. In contrast, nitrite and N(2)O were essentially not produced by nitrate-supplemented soil homogenates. The most probable numbers of fermentative anaerobes and microbes that used nitrate as a terminal electron acceptor were approximately 2 orders of magnitude higher in the earthworm gut than in the soil from which the earthworms originated. The fermentative anaerobes in the gut and soil displayed similar physiological functionalities. A total of 136 N(2)O-producing isolates that reduced either nitrate or nitrite were obtained from high serial dilutions of gut homogenates. Of the 25 representative N(2)O-producing isolates that were chosen for characterization, 22 isolates exhibited >99% 16S rRNA gene sequence similarity with their closest cultured relatives, which in most cases was a soil bacterium, most isolates were affiliated with the gamma subclass of the class Proteobacteria or with the gram-positive bacteria with low DNA G+C contents, and 5 isolates were denitrifiers and reduced nitrate to N(2)O or N(2). The initial N(2)O production rates of denitrifiers were 1 to 2 orders of magnitude greater than those of the nondenitrifying isolates. However, most nondenitrifying nitrate dissimilators produced nitrite and might therefore indirectly stimulate the production of N(2)O via nitrite-utilizing denitrifiers in the gut. The results of this study suggest that most of the N(2)O emitted by earthworms is due to the activation of

  6. Relationship between N2O Fluxes from an Almond Soil and Denitrifying Bacterial Populations Estimated by Quantitative PCR

    Science.gov (United States)

    Matiasek, M.; Suddick, E. C.; Smart, D. R.; Scow, K. M.

    2008-12-01

    Cultivated soils emit substantial quantities of nitrous oxide (N2O), a greenhouse gas with almost 300 times the radiative forcing potential of CO2. Agriculture-related activities generate from 6 to 35 Tg N2O-N per year, or about 60 to 70% of global production. The microbial processes of nitrification, denitrification and nitrifier denitrification are major biogenic sources of N2O to the atmosphere from soils. Denitrification is considered the major source of N2O especially when soils are wet. The microbial N transformations that produce N2O depend primarily on nitrogen (N) fertilizer, with water content, available carbon and soil temperature being secondary controllers. Despite the fact that microbial processes are responsible for N2O emissions, very little is known about the numbers or types of populations involved. The objective of this study was to relate changes in denitrifying population densities, using quantitative PCR (qPCR) of functional genes, to N2O emissions in a fertilized almond orchard. Quantitative PCR targeted three specific genes involved in denitrification: nirS, nirK and nosZ. Copy numbers of the genes were related back to population densities and the portion of organisms likely to produce nitrous oxide. The study site, a 21.7 acre almond orchard fitted with micro-sprinklers, was fertigated (irrigated and fertilized simultaneously) with 50 lbs/acre sodium nitrate in late March 2008, then irrigated weekly. Immediately after the initial fertigation, fluxes of N2O and CO2, moisture content, inorganic N and denitrification gene copy numbers were measured 6 times over 24 days. Despite the fact that N2O emissions increased following fertigation, there was no consistent increase in any of the targeted genes. The genes nirK and nirS ranged from 0.4-1.4 × 107 and 0.4-1.4 × 108, whereas nosZ ranged from 2-8 × 106 copy numbers per g soil, respectively. Considerable variation, compounded by the small sample sizes used for DNA analysis, made it difficult

  7. Effect of litter layer on soil-atmosphere N2O flux of a subtropical pine plantation in China

    Science.gov (United States)

    Wang, Yidong; Wang, Huimin; Wang, Zhong-Liang; Ma, Zeqing; Dai, Xiaoqin; Wen, Xuefa; Liu, Yunfen

    2014-01-01

    Forest soils are important sources for nitrous oxide (N2O), but how the surface litter layer affects these sources is still unclear. Seasonal rainfall in the subtropical monsoon climate provides a unique opportunity to examine soil-atmosphere N2O flux under a wide range of soil water content. We studied this question over 3 years using a litter removal method in a 20-year-old pine plantation (Pinus elliottii) in subtropical China. Annual mean chamber-based soil-atmosphere N2O fluxes of the control (FCK) and litter-free (FLF) treatments were 6.07 and 5.17 μg N2O m-2 h-1, respectively. Removal of the litter layer reduced 15% of soil N2O emissions, suggesting the mineral soil as the dominant factor that determines soil N2O emissions. Seasonal FCK and FLF were both significantly influenced by water-filled pore space (WFPS) but not by soil temperature (TS). However, FCK and FLF were both correlated with TS during the wet season (January-June) but not during the dry season (July-December). During the wet season, FCK and FLF were 84% and 132% higher than during the dry season, respectively. In contrast, seasonal litter-based N2O fluxes (FCK-LF = FCK - FLF) were not correlated with WFPS and TS. During the dry season, however, a positive relationship was observed for FCK-LF and WFPS. In the context of climate change and human activities, future changes in soil environment and surface litter management will alter the strength of soil N2O emissions of the subtropical pine forests in China.

  8. Stress Corrosion Cracking Behavior of LD10 Aluminum Alloy in UDMH and N2O4 propellant

    Science.gov (United States)

    Zhang, Youhong; Chang, Xinlong; Liu, Wanlei

    2018-03-01

    The LD10 aluminum alloy double cantilever beam specimens were corroded under the conditions of Unsymmetric Uimethyl Hydrazine (UDMH), Dinitrogen Tetroxide (N2O4), and 3.5% NaCl environment. The crack propagation behavior of the aluminum alloy in different corrosion environment was analyzed. The stress corrosion cracking behavior of aluminum alloy in N2O4 is relatively slight and there are not evident stress corrosion phenomenons founded in UDMH.

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

    Science.gov (United States)

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

    2015-03-01

    Mitigation of nitrous oxide (N2 O) emission from swine wastewater treatment was demonstrated in an aerobic bioreactor packed with carbon fibers (CF reactor). The CF reactor had a demonstrated advantage in mitigating N2 O emission and avoiding NOx (NO3  + NO2 ) accumulation. The N2 O emission factor was 0.0003 g N2 O-N/gTN-load in the CF bioreactor compared to 0.03 gN2 O-N/gTN-load in an activated sludge reactor (AS reactor). N2 O and CH4 emissions from the CF reactor were 42 g-CO2 eq/m(3) /day, while those from the AS reactor were 725 g-CO2 eq/m(3) /day. The dissolved inorganic nitrogen (DIN) in the CF reactor removed an average of 156 mg/L of the NH4 -N, and accumulated an average of 14 mg/L of the NO3 -N. In contrast, the DIN in the AS reactor removed an average 144 mg/L of the NH4 -N and accumulated an average 183 mg/L of the NO3 -N. NO2 -N was almost undetectable in both reactors. © 2014 Japanese Society of Animal Science.

  10. N2O emissions from secondary clarifiers and their contribution to the total emissions of the WWTP.

    Science.gov (United States)

    Mikola, Anna; Heinonen, Mari; Kosonen, Heta; Leppänen, Maarit; Rantanen, Pirjo; Vahala, Riku

    2014-01-01

    Recent studies have indicated that the emissions of nitrous oxide, N2O, constitute a major part of the carbon footprint of wastewater treatment plants (WWTPs). Denitrification occurring in the secondary clarifier basins has been observed by many researchers, but until now N2O emissions from secondary clarifiers have not been widely reported. The objective of this study was to measure the N2O emissions from secondary clarifiers and weigh the portion they could represent of the overall emissions at WWTPs. Online measurements over several days were carried out at four different municipal WWTPs in Finland in cold weather conditions (March) and in warm weather conditions (June-July). An attempt was made to define the conditions in which N2O emissions from secondary clarifiers may occur. It was evidenced that large amounts of N2O can be emitted from the secondary clarifiers, and that the emissions have long-term variation. It was assumed that part of the N2O released in secondary clarification was originally formed in the activated sludge basin. The emissions from secondary clarification thus seem to be dependent on conditions of the nitrification and denitrification accomplished in the denitrification-nitrification process and on the amount of sludge stored in the secondary clarifiers.

  11. Probabilistic Estimates of Global Marine N2O Emissions within the Bern3D Earth System Model of Intermediate Complexity

    Science.gov (United States)

    Keller, K. M.; Battaglia, G.; Joos, F.

    2016-02-01

    Nitrous oxide (N2O) is a radiatively active atmospheric trace gas (currently 325 ppb, increasing by 0.25% yr-1) and is emitted to the atmosphere from poorly constrained microbial processes on land and in the oceans. The latest estimates given by the IPCC for marine N2O sources range from 1.8-9.4 TgN yr-1. Marine N2O production is commonly parameterized as a function of organic matter remineralization, oxygen concentrations, or temperature to account for (chemo-autotrophic) nitrification and (chemo-heterotrophic) denitrification processes. We implemented different production schemes in the cost-efficient Bern3D Earth-System Model of Intermediate Complexity which features a 3-D frictional-geostrophic ocean and an OCMIP2-type marine carbon cycle. We optimize the parameters governing N2O production in a probabilistic, Monte-Carlo-type, Bayesian framework by applying observed dissolved N2O data, compiled in the MEMENTO database, as constraints. N2O emissions of the observation-constrained model ensemble will then be determined for both future and past (e.g. Younger-Dryas) environmental conditions.

  12. Sterilization of E. coli bacterium in a flowing N2-O2 post-discharge reactor

    International Nuclear Information System (INIS)

    Villeger, S; Cousty, S; Ricard, A; Sixou, M

    2003-01-01

    Effective destruction of Escherichia coli (E. coli) bacteria has been obtained in a flowing N 2 -O 2 microwave post-discharge reactor. The sterilizing agents are the O atoms and the UV emissions of NOβ which are produced by N and O atoms recombination in the reactor. In the following plasma conditions: pressure 5 Torr, flow rate 1 L n min -1 , microwave power of 100 W in a quartz tube of 5 mm, an O atom density of 2.5x10 15 cm -3 is measured by NO titration in the post-discharge reactor with UV emission in a N 2 -(5%)O 2 gas mixture. Full destruction of 10 13 cfu ml -1 E. coli is observed after a treatment time of 25 min. (rapid communication)

  13. Increasing thermal drying temperature of biosolids reduced nitrogen mineralisation and soil N2O emissions

    DEFF Research Database (Denmark)

    Case, Sean; Gomez Muñoz, Beatriz; Magid, Jakob

    2016-01-01

    . This will be of importance for the value of the biosolids when used to fertilise crops. We sourced AD biosolids from a Danish waste water treatment plant (WWTP) and dried it in the laboratory at 70, 130, 190 or 250 °C to >95 % dry matter content. Also, we sourced biosolids from the WWTP dried using its in-house thermal......Previous studies found that thermally dried biosolids contained more mineralisable organic nitrogen (N) than the raw or anaerobically digested (AD) biosolids they were derived from. However, the effect of thermal drying temperature on biosolid N availability is not well understood......) and N2O production was also the lowest in treatments of the highest drying temperature, suggesting that this material was more recalcitrant. Overall, thermal drying temperature had a significant influence on N availability from the AD biosolids, but drying did not improve the N availability...

  14. Structural and magnetic transitions in spinel FeM n2O4 single crystals

    Science.gov (United States)

    Nepal, Roshan; Zhang, Qiang; Dai, Samuel; Tian, Wei; Nagler, S. E.; Jin, Rongying

    2018-01-01

    Materials that form the spinel structure are known to exhibit geometric frustration, which can lead to magnetic frustration as well. Through magnetization and neutron diffraction measurements, we find that FeM n2O4 undergoes one structural and two magnetic transitions. The structural transition occurs at Ts˜595 K from cubic at high temperatures to tetragonal at low temperatures. Two magnetic transitions are ferrimagnetic at TFI -1˜373 K and TFI -2˜50 K , respectively. Further investigation of the specific heat, thermal conductivity, and Seebeck coefficient confirms both magnetic transitions. Of particular interest is that there is a significant magnetic contribution to the low-temperature specific heat and thermal conductivity, providing a unique system to study heat transport by magnetic excitations.

  15. Photochemical oxidation of americium(3) in bicarbonate-carbonate solutions saturated with N2O

    International Nuclear Information System (INIS)

    Shilov, V.P.; Yusov, A.B.

    1993-01-01

    The influence of UV radiation on 1.1x10 -4 mol/l Am(3) in bicarbonate-carbonate solutions of sodium and potassium saturated with N 2 O was studied by spectrographic method. In all the cases Am(4) was formed as a primary product. Initial rate of Am(4) accumulation remains stable in solutions up to HCO 3 - or HCO 3 - +CO 3 2- concentration of approximately 1.5 mol/l, but it decreases in case of their higher concentration. In solutions with pH 8.4-10 Am(4) disproportionates at a slow rate and the method suggested permits attaining practically 100% yield of it

  16. Global trends and uncertainties in terrestrial denitrification and N2O emissions

    Science.gov (United States)

    Bouwman, A. F.; Beusen, A. H. W.; Griffioen, J.; Van Groenigen, J. W.; Hefting, M. M.; Oenema, O.; Van Puijenbroek, P. J. T. M.; Seitzinger, S.; Slomp, C. P.; Stehfest, E.

    2013-01-01

    Soil nitrogen (N) budgets are used in a global, distributed flow-path model with 0.5° × 0.5° resolution, representing denitrification and N2O emissions from soils, groundwater and riparian zones for the period 1900–2000 and scenarios for the period 2000–2050 based on the Millennium Ecosystem Assessment. Total agricultural and natural N inputs from N fertilizers, animal manure, biological N2 fixation and atmospheric N deposition increased from 155 to 345 Tg N yr−1 (Tg = teragram; 1 Tg = 1012 g) between 1900 and 2000. Depending on the scenario, inputs are estimated to further increase to 408–510 Tg N yr−1 by 2050. In the period 1900–2000, the soil N budget surplus (inputs minus withdrawal by plants) increased from 118 to 202 Tg yr−1, and this may remain stable or further increase to 275 Tg yr−1 by 2050, depending on the scenario. N2 production from denitrification increased from 52 to 96 Tg yr−1 between 1900 and 2000, and N2O–N emissions from 10 to 12 Tg N yr−1. The scenarios foresee a further increase to 142 Tg N2–N and 16 Tg N2O–N yr−1 by 2050. Our results indicate that riparian buffer zones are an important source of N2O contributing an estimated 0.9 Tg N2O–N yr−1 in 2000. Soils are key sites for denitrification and are much more important than groundwater and riparian zones in controlling the N flow to rivers and the oceans. PMID:23713114

  17. Permafrost collapse alters soil carbon stocks, respiration, CH4 , and N2O in upland tundra.

    Science.gov (United States)

    Abbott, Benjamin W; Jones, Jeremy B

    2015-12-01

    Release of greenhouse gases from thawing permafrost is potentially the largest terrestrial feedback to climate change and one of the most likely to occur; however, estimates of its strength vary by a factor of thirty. Some of this uncertainty stems from abrupt thaw processes known as thermokarst (permafrost collapse due to ground ice melt), which alter controls on carbon and nitrogen cycling and expose organic matter from meters below the surface. Thermokarst may affect 20-50% of tundra uplands by the end of the century; however, little is known about the effect of different thermokarst morphologies on carbon and nitrogen release. We measured soil organic matter displacement, ecosystem respiration, and soil gas concentrations at 26 upland thermokarst features on the North Slope of Alaska. Features included the three most common upland thermokarst morphologies: active-layer detachment slides, thermo-erosion gullies, and retrogressive thaw slumps. We found that thermokarst morphology interacted with landscape parameters to determine both the initial displacement of organic matter and subsequent carbon and nitrogen cycling. The large proportion of ecosystem carbon exported off-site by slumps and slides resulted in decreased ecosystem respiration postfailure, while gullies removed a smaller portion of ecosystem carbon but strongly increased respiration and N2 O concentration. Elevated N2 O in gully soils persisted through most of the growing season, indicating sustained nitrification and denitrification in disturbed soils, representing a potential noncarbon permafrost climate feedback. While upland thermokarst formation did not substantially alter redox conditions within features, it redistributed organic matter into both oxic and anoxic environments. Across morphologies, residual organic matter cover, and predisturbance respiration explained 83% of the variation in respiration response. Consistent differences between upland thermokarst types may contribute to the

  18. CH4 and N2O from mechanically turned windrow and vermicomposting systems following in-vessel pre-treatment.

    Science.gov (United States)

    Hobson, A M; Frederickson, J; Dise, N B

    2005-01-01

    Methane (CH4) and nitrous oxide (N2O) are included in the six greenhouse gases listed in the Kyoto protocol that require emission reduction. To meet reduced emission targets, governments need to first quantify their contribution to global warming. Composting has been identified as an important source of CH4 and N2O. With increasing divergence of biodegradable waste from landfill into the composting sector, it is important to quantify emissions of CH4 and N2O from all forms of composting and from all stages. This study focuses on the final phase of a two stage composting process and compares the generation and emission of CH4 and N2O associated with two differing composting methods: mechanically turned windrow and vermicomposting. The first stage was in-vessel pre-treatment. Source-segregated household waste was first pre-composted for seven days using an in-vessel system. The second stage of composting involved forming half of the pre-composted material into a windrow and applying half to vermicomposting beds. The duration of this stage was 85 days and CH4 and N2O emissions were monitored throughout for both systems. Waste samples were regularly subjected to respirometry analysis and both processes were found to be equally effective at stabilising the organic matter content. The mechanically turned windrow system was characterised by emissions of CH4 and to a much lesser extent N2O. However, the vermicomposting system emitted significant fluxes of N2O and only trace amounts of CH4. In-vessel pre-treatment removed considerable amounts of available C and N prior to the second stage of composting. This had the effect of reducing emissions of CH4 and N2O from the second stage compared to emissions from fresh waste found in other studies. The characteristics of each of the two composting processes are discussed in detail. Very different mechanisms for emission of CH4 and N2O are proposed for each system. For the windrow system, development of anaerobic zones were

  19. Short-term nitrogen additions can shift a coastal wetland from a sink to a source of N2O

    Science.gov (United States)

    Moseman-Valtierra, Serena; Gonzalez, Rosalinda; Kroeger, Kevin D.; Tang, Jianwu; Chao, Wei Chun; Crusius, John; Bratton, John F.; Green, Adrian; Shelton, James

    2011-01-01

    Coastal salt marshes sequester carbon at high rates relative to other ecosystems and emit relatively little methane particularly compared to freshwater wetlands. However, fluxes of all major greenhouse gases (N2O, CH4, and CO2) need to be quantified for accurate assessment of the climatic roles of these ecosystems. Anthropogenic nitrogen inputs (via run-off, atmospheric deposition, and wastewater) impact coastal marshes. To test the hypothesis that a pulse of nitrogen loading may increase greenhouse gas emissions from salt marsh sediments, we compared N2O, CH4 and respiratory CO2fluxes from nitrate-enriched plots in a Spartina patens marsh (receiving single additions of NaNO3 equivalent to 1.4 g N m−2) to those from control plots (receiving only artificial seawater solutions) in three short-term experiments (July 2009, April 2010, and June 2010). In July 2009, we also compared N2O and CH4 fluxes in both opaque and transparent chambers to test the influence of light on gas flux measurements. Background fluxes of N2O in July 2009 averaged −33 μmol N2O m−2 day−1. However, within 1 h of nutrient additions, N2O fluxes were significantly greater in plots receiving nitrate additions relative to controls in July 2009. Respiratory rates and CH4 fluxes were not significantly affected. N2O fluxes were significantly higher in dark than in transparent chambers, averaging 108 and 42 μmol N2O m−2 day−1 respectively. After 2 days, when nutrient concentrations returned to background levels, none of the greenhouse gas fluxes differed from controls. In April 2010, N2O and CH4 fluxes were not significantly affected by nitrate, possibly due to higher nitrogen demands by growing S. patens plants, but in June 2010 trends of higher N2O fluxes were again found among nitrate-enriched plots, indicating that responses to nutrient pulses may be strongest during the summer. In terms of carbon equivalents, the highest average N2O and CH4 fluxes observed, exceeded half

  20. Nitrous Oxide (N2O) Emissions in Wheat and Canola Crops under Fertigation Management in the Canadian Prairies

    Science.gov (United States)

    Chai, L.; Hernandez Ramirez, G.; Dyck, M. F.; Pauly, D.; Kryzanowski, L.; Middleton, A.; Powers, L. A.; Lohstraeter, G.; Werk, D.

    2016-12-01

    Nitrous oxide (N2O) emissions from agricultural soils contribute significantly to the amount of greenhouse gases released to the atmosphere every year. Farming practices, such as fertigation in which nitrogen fertilizer is added to crops through irrigation water, could increase the risk for N2O losses. To assess the effect of N fertigation rates on N2O production, field chambers were used to collect weekly gas samples throughout the 2015 growing season in wheat (Triticum aestivum) and canola (Brassica Napus) plots in southern Alberta, Canada. Synthetic fertilizer was either added at seeding or both added at seeding and through irrigation water at one early crop growth stage. The 6 fertilizer treatments were: 60, 90 and 120 kg N ha-1 added at seeding in early May, and 30, 60 and 90 kg N ha-1 at seeding plus another 30 kg N ha-1 added through fertigation in mid-June. Controls with no fertilizer were also evaluated, and each treatment was replicated 4 times. In the wheat plots at a fertilization rate of 120 kg N ha-1, irrespective of single or split application, a larger N2O flux was produced compared to the control (P = 0.024). Similarly, in canola, a total N addition of 90 kg N ha-1 also led to larger N2O fluxes than the control (P = 0.035). The use of fertigation to split the N application had no effect on the N2O emissions in canola; however, in wheat, there was a statistical difference between emissions from 90 kg N ha-1 added all at seeding versus 90 kg N ha-1 split between seeding (60) and fertigation (30); splitting the fertilizer resulted in a 62% decrease in the overall N2O emissions (324 g vs. 524 g N2O-N ha-1; P = 0.039). No other N rates resulted in statistically different N2O emissions when N application was split. These results suggest that fertigation can reduce N2O emissions, but only at moderate N rates (90 kg ha-1 yr-1); conversely, when lower (60) or higher (120) rates are split, emissions remain unaffected.

  1. Biochar reduces efficiency of nitrification inhibitor 3,4-dymethylpyrazole phospate (DMPP) mitigating N2O emissions.

    Science.gov (United States)

    Fuertes-Mendizábal, Teresa; Huérfano, Ximena; Menéndez, Sergio; González-Murua, Carmen; Begoña González-Moro, Mª; Ippolito, James; Kamann, Claudia; Wrage-Mönnig, Nicole; Borchard, Nils; Cayuela, Maria Luz; Spokas, Kurt; Sigua, Gilbert; Novak, Jeff; Estavillo, José Mª

    2017-04-01

    Nitrous oxide (N2O) is the strongest greenhouse gas associated with agricultural soils. Current agricultural practices, based on the use of N fertilizers, can lead to environmental N losses, with some losses occurring as N2O emissions. Among the strategies suggested by the Intergovernmental Panel on Climate Change to decrease N losses through agriculture is the utilization of nitrification inhibitors, such as DMPP (3,4-dimethylpyrazole phosphate). This compound inhibits nitrification, thus reducing N2O emissions. However, the efficiency of DMPP might be affected by soil amendments. One soil amendment is biochar, which typically increases soil C, can reduce N2O emissions, affect the retention of water, and alter the C and N cycle. Nevertheless, these effects are not uniformly observed across varying soil types, N fertilization schemes and biochar properties. Assuming that both DMPP and biochars with C/N > 30 ratios are presumably able to reduce soil N2O emissions, the aim of this study was to evaluate the synergic effect of a woody biochar applied in combination with DMPP on N2O emissions. For this purpose, a laboratory incubation study was conducted with a silt loam grassland soil and a biochar obtained from Pinus taeda at 500°C. The experimental design consisted of an arrangement including two biochar levels (0 and 2% (w/w)), three fertilization levels (unfertilized, fertilized and fertilized+DMPP) and two soil water content levels (40% and 80% of water filled pore space, WFPS), giving rise to 12 different individual treatments with four replications of each treatment. Soil N2O emissions were monitored over the incubation period (163 days). Results showed that DMPP reduced N2O emissions to levels comparable to the unfertilized controls. Biochar showed ability to mitigate N2O emissions only at the low soil water content (40% WFPS). However, when DMPP was applied to the biochar amended soil, a counteracting effect was observed, since the reduction in N2O emissions

  2. Observational Insights into N2O5 Heterogeneous Chemistry: Influencing Factors and Contribution to Wintertime Air Pollution

    Science.gov (United States)

    McDuffie, E. E.; Fibiger, D. L.; Womack, C.; Dube, W. P.; Lopez-Hilfiker, F.; Goldberger, L.; Thornton, J. A.; Shah, V.; Jaegle, L.; Guo, H.; Weber, R. J.; Schroder, J. C.; Campuzano Jost, P.; Jimenez, J. L.; Franchin, A.; Middlebrook, A. M.; Baasandorj, M.; Brown, S. S.

    2017-12-01

    Chemical mechanisms that underlie wintertime air pollution, including tropospheric ozone and aerosol nitrate, are poorly characterized. Due to colder temperatures and fewer hours of solar radiation, nocturnal heterogeneous uptake of N2O5 plays a relatively larger role during wintertime in controlling the oxidation of NOx (=NO+NO2) and its influence on ozone and soluble nitrate. After uptake to aerosol, N2O5 can act as both a nocturnal NOx reservoir and sink depending on the partitioning between its nitric acid and photo labile, ClNO2 reaction products. In addition, N2O5 itself can act as a NOx reservoir if the aerosol uptake coefficient is small. As a result, the nocturnal fate of N2O5 dictates the amount of NOx in an air parcel and the subsequent formation of aerosol nitrate and following-day ozone. Models of winter air pollution therefore require accurate parameterization of the N2O5 uptake coefficient, as well as factors that control its magnitude and N2O5 product partitioning. There are currently only a small number of ambient N2O5 and ClNO2 observations during the winter season concurrent with measurements of relevant variables such as aerosol size distributions and composition. The Wintertime INvestigation of Transport, Emissions, and Reactivity (WINTER) campaign conducted 10 nighttime research flights with the NCAR C-130 over the eastern U.S. during February and March, 2015. The more recent Utah Wintertime Fine Particulate Study (UWFPS) conducted over 20 research flights with the NOAA twin otter aircraft during January-February 2017 in three mountain basins near and including Salt Lake City, Utah. The two campaigns were similarly instrumented and have provided the first aircraft observations of N2O5, ClNO2, and aerosol composition in the wintertime boundary layer in these urban-influenced regions. Analysis of heterogeneous chemistry under a wide range of real environmental conditions provides insight into the factors controlling the N2O5 uptake coefficient

  3. Spatial and temporal variability of N2O in the surface groundwater: a detailed analysis from a sandy aquifer in northern Germany

    OpenAIRE

    Heide, C.; Böttcher, J.; Deurer, M.; Duijnisveld, W.; Weymann, D.; Well, R.

    2009-01-01

    The knowledge of the spatial and temporal variability of N2O concentrations in surface groundwater is the first step towards upscaling of potential indirect N2O emissions from the scale of localized samples to aquifers. This study aimed to investigate the spatial and the temporal variability of N2O concentrations at different scales in the surface groundwater of a denitrifying aquifer in northern Germany. The spatial variability of N2O concentrations in the surface groundwater was analysed at...

  4. Assessment of various practices of the mitigation of N2O emissions from the arable soils of Poland

    Directory of Open Access Journals (Sweden)

    Sosulski Tomasz

    2017-03-01

    Full Text Available This review assesses the adaptability and effectiveness of the basic practices to mitigate the N2O emissions from the arable land in the climate, soil and agricultural conditions of Poland. We have analyzed the decrease in the nitrogen-based fertilization, selection of the fertilizer nitrogen forms, use of biological inhibitors of nitrogen transformation in the soil, control of the acidic soil reaction, reduction in the natural fertilizers use and afforestation of the low productive soils. The challenge evaluating the effectiveness of mitigation practices lies in the inadequacy of the national data on N2O soil emissions in particular agrotechnical conditions. In Poland, circumstances that favor intensive N2O emissions from the arable soils occur uncommonly, as shows the analysis of the literature reporting on the country climate, soil and agricultural conditions alongside the N2O emissions from soils under various cultivation conditions. Consequently, the effectiveness of mitigation practices that relies on an extensification of plant production may be insufficient. It can be assumed that, at the doses of nitrogen fitting the nutritional needs of crops, the soil N2O emissions are low and do not meaningfully differ from the emissions from untreated soils (literature data point to limited N2O emission from arable soils treated with N doses of ≤150-200 kg N·ha-1. The effectiveness of the nitrogen fertilization reduction as an N2O emissions mitigation practice is restricted to intensive farming. A universal registry of the mineral and natural fertilization use could help identify the agricultural holdings with a potential for high N2O emission and foster a targeted application of mitigation practices. It is suggested that normalization and maintenance of the optimum (i.e. close to neutral soil pH should become a more common practice of N2O emissions mitigation in Poland in view of the extent of arable soils acidification and the literature data

  5. An automated GC-C-GC-IRMS setup to measure palaeoatmospheric δ13C-CH4, δ15N-N2O and δ18O-N2O in one ice core sample

    Directory of Open Access Journals (Sweden)

    P. Sperlich

    2013-08-01

    Full Text Available Air bubbles in ice core samples represent the only opportunity to study the mixing ratio and isotopic variability of palaeoatmospheric CH4 and N2O. The highest possible precision in isotope measurements is required to maximize the resolving power for CH4 and N2O sink and source reconstructions. We present a new setup to measure δ13C-CH4, δ15N-N2O and δ18O-N2O isotope ratios in one ice core sample and with one single IRMS instrument, with a precision of 0.09, 0.6 and 0.7‰, respectively, as determined on 0.6–1.6 nmol CH4 and 0.25–0.6 nmol N2O. The isotope ratios are referenced to the VPDB scale (δ13C-CH4, the N2-air scale (δ15N-N2O and the VSMOW scale (δ18O-N2O. Ice core samples of 200–500 g are melted while the air is constantly extracted to minimize gas dissolution. A helium carrier gas flow transports the sample through the analytical system. We introduce a new gold catalyst to oxidize CO to CO2 in the air sample. CH4 and N2O are then separated from N2, O2, Ar and CO2 before they get pre-concentrated and separated by gas chromatography. A combustion unit is required for δ13C-CH4 analysis, which is equipped with a constant oxygen supply as well as a post-combustion trap and a post-combustion GC column (GC-C-GC-IRMS. The post-combustion trap and the second GC column in the GC-C-GC-IRMS combination prevent Kr and N2O interferences during the isotopic analysis of CH4-derived CO2. These steps increase the time for δ13C-CH4 measurements, which is used to measure δ15N-N2O and δ18O-N2O first and then δ13C-CH4. The analytical time is adjusted to ensure stable conditions in the ion source before each sample gas enters the IRMS, thereby improving the precision achieved for measurements of CH4 and N2O on the same IRMS. The precision of our measurements is comparable to or better than that of recently published systems. Our setup is calibrated by analysing multiple reference gases that were injected over bubble-free ice samples. We show

  6. Potential impact on the global atmospheric N2O budget of the increased nitrogen input required to meet future global food demands

    NARCIS (Netherlands)

    Mosier, A.; Kroeze, C.

    2000-01-01

    In most soils, biogenic formation of N2O is enhanced by an increase in available mineral N through increased nitrification and denitrification. N-fertilization, therefore, directly results in additional N2O formation. In addition, these inputs may lead to indirect formation of N2O after N leaching

  7. Improving estimates of N2O emissions for western and central Europe using a Bayesian inversion approach

    Science.gov (United States)

    Thompson, R. L.; Gerbig, C.; Roedenbeck, C.; Heimann, M.

    2009-04-01

    The nitrous oxide (N2O) mixing ratio has been increasing in the atmosphere since the industrial revolution, from 270 ppb in 1750 to 320 ppb in 2007 with a steady growth rate of around 0.26% since the early 1980's. The increase in N2O is worrisome for two main reasons. First, it is a greenhouse gas; this means that its atmospheric increase translates to an enhancement in radiative forcing of 0.16 ± 0.02 Wm-2 making it currently the fourth most important long-lived greenhouse gas and is predicted to soon overtake CFC's to become the third most important. Second, it plays an important role in stratospheric ozone chemistry. Human activities are the primary cause of the atmospheric N2O increase. The largest anthropogenic source of N2O is from the use of N-fertilizers in agriculture but fossil fuel combustion and industrial processes, such as adipic and nitric acid production, are also important. We present a Bayesian inversion approach for estimating N2O fluxes over central and western Europe using high frequency in-situ concentration data from the Ochsenkopf tall tower (50 °01′N, 11 °48′, 1022 masl). For the inversion, we employ a Lagrangian-type transport model, STILT, which provides source-receptor relationships at 10 km using ECMWF meteorological data. The a priori flux estimates used were from IER, for anthropogenic, and GEIA, for natural fluxes. N2O fluxes were retrieved monthly at 2 x 2 degree spatial resolution for 2007. The retrieved N2O fluxes showed significantly more spatial heterogeneity than in the a priori field and considerable seasonal variability. The timing of peak emissions was different for different regions but in general the months with the strongest emissions were May and August. Overall, the retrieved flux (anthropogenic and natural) was lower than in the a priori field.

  8. Heterogeneous kinetics of N2O5 reactive uptake and chlorine activation in authentic biomass burning aerosol

    Science.gov (United States)

    Sullivan, R. C.; Jahl, L.; Goldberger, L.; Ahern, A.; Thornton, J. A.

    2017-12-01

    Nitryl chloride (ClNO2) is a nighttime reservoir of NOx that is formed from the uptake of dinitrogen pentoxide (N2O5) into particles containing chloride. The formation of ClNO2 from heterogeneous reactions of N2O5(g) with authentic biomass burning aerosol has not previously been studied. We observed the rapid production of N2O5 and then ClNO2 during dark chemical transformations of biomass burning aerosol produced from a variety of fuels using both a smog chamber and an aerosol flow tube reactor. Iodide adduct chemical ionization mass spectrometry was used to measure gas phase ClNO2 and N2O5, and acetate chemical ionization mass spectrometry to measure gaseous HCl and other compounds, while a soot particle aerosol mass spectrometer measured changes in aerosol composition as chloride was displaced by nitrate. Upon the addition of ozone to the biomass burning smoke, N2O5 was always rapidly formed and ClNO2 was subsequently detected in the gas phase. During experiments at high relative humidity, we observed decreases in particulate chloride and increases in particulate nitrate which we believe are due to acid displacement of HCl(g) by HNO3 since no additional ClNO2 was produced in the gas phase. The reactive uptake probability of N2O5 on authentic biomass burning aerosol and the yield of ClNO2 were determined for the first time using chamber and flow tube experiments on smoke from biomass fuels including sawgrass, giant cutgrass, palmetto leaves, and ponderosa pine. These experiments confirm the formation of N2O5 and ClNO2 in biomass burning emissions and suggest that biomass burning is a likely source of continental ClNO2 and HCl.

  9. Dissolution and Release of Gaseous Nitrogen (N2, N2O) in the Source Region of the Yellow River

    Science.gov (United States)

    Zhang, L.; Xia, X.; Wang, J.

    2017-12-01

    Nitrogen is an important biogenic element. The migration and transformation of nitrogen in rivers is an important process affecting global nitrogen cycling and greenhouse gas emissions. However, there is a lack of research on nitrogen removal and greenhouse gas emission characteristics of high altitude rivers. In this work, the spatial and temporal variations of dissolved nitrogen (N2 and N2O) concentrations, saturation, and release flux as well as their responses to environmental factors were studied in the Yellow River source area, a typical high altitude river. The results showed that the dissolved concentrations of N2 and N2O in the rivers were 8.24-137.75 μmol.L-1 and 2.57-31.94 nmol.L-1, respectively. N2 and N2O saturation were greater than 100% for all the sampling sites, indicating that the river is a release source for atmosphere N2 and N2O. Correspondingly, the fluxes of N2 and N2O from river water to atmosphere were 24.12-1606.57 mmol (m2.d) -1 and 12.96-276.81 μmol (m2.d) -1, respectively. Generally, the dissolution concentration and release flux of N2 and N2O in July were larger than that in May. The concentrations of N2 and N2O in river water were related to the environmental factors, and the dissolved concentration of N2 in the surface water was significantly positively correlated with water temperature, NH4+-N and total inorganic nitrogen (DIN) (p<0.01). The dissolved concentration of N2O was significantly positively correlated with the content of suspended particulates, DO, and DIN (p<0.01). Thus, DIN is a key factor in the process of N2 and N2O formation. This study can help to understand the nitrogen cycling in high-altitude rivers and provide basic data for a comprehensive assessment of global river nitrogen loss. Key Words: Source Region of the Yellow River; Gaseous Nitrogen; Nitrogen loss; High altitude river

  10. N2O adsorption and decomposition over ZnO(0001) doped graphene: Density functional theory calculations

    Science.gov (United States)

    Gholizadeh, Reza; Yu, Yang-Xin; Wang, Yujun

    2017-10-01

    The main objective of this study is density functional theory investigations on adsorption and decomposition of N2O on ZnO(0001)-G nanocomposite. The adsorption and decomposition of small molecules on the magnetic oxides containing transition metals are relatively rare due to the modeling difficulties using current density functional approximations. A molecular modeling of the reaction mechanism was studied in this work through ab initio modeling of the catalytic adsorption and decomposition of N2O on ZnO(0001)-G. DFT was used to study the molecular mechanism of conceivable elementary steps of the decomposition of N2O over the most stable (0001) surface. Three reactions including the N2sbnd O bond cleavage, the oxygen atom transfer, forming a surface peroxy group O22- were studied. The horse-like (Nsbnd Nsbnd O), parallel (Nsbnd Nsbnd O) and lying-atop-011 (Osbnd Nsbnd N) with all three atoms of the N2O molecule interacting with the surface have been found as more stable adsorption forms, which have adsorption energies of -0.27, -0.23 and -0.23 eV, respectively. The activation energies of the N2O decomposition through mentioned reactions were found to be 2.73, 0.48 and 0.63 eV, respectively. The obtained results reveal that ZnO(0001)-G is not only an efficient but also a green catalyst in comparison with others such as Mn-G.

  11. Intercomparison of in situ CRDS and CEAS for measurements of atmospheric N2O5in Beijing, China.

    Science.gov (United States)

    Li, Zhiyan; Hu, Renzhi; Xie, Pinhua; Wang, Haichao; Lu, Keding; Wang, Dan

    2018-02-01

    Dinitrogen pentoxide (N 2 O 5 ) is one of the basic trace gases which plays a key role in nighttime atmosphere. An intercomparison and validation of different N 2 O 5 measurement methods is important for determining the true accuracy of these methods. Cavity ring down spectroscopy (CRDS) and cavity enhanced absorption spectrometer (CEAS) were used to measure N 2 O 5 at the campus of the University of Chinese Academy of Sciences (UCAS) from February 21, 2016 to March 4, 2016. The detection limits were 1.6ppt (1σ) at 30s intervals for the CEAS instrument and 3.9ppt (1σ) at 10s time resolution for the CRDS instrument respectively. In this study, a comparison of the 1min observations from the two instruments was presented. The two data sets showed a good agreement within their uncertainties, with an absolute shift of 15.6ppt, slope of 0.94 and a correlation coefficient R 2 =0.97. In general, the difference between the CRDS and CEAS instruments for N 2 O 5 measurement can be explained by their combined measurement uncertainties. However, high relative humidity (>60%) and high PM2.5 concentration (>200μg/m 3 ) may contribute to the discrepancies. The excellent agreement between the measurement by the CRDS and CEAS instruments demonstrates the capability of the two instruments for accurately measuring N 2 O 5 with high sensitivity. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Effects of clover density on N2O emissions and plant-soil N transfers in a fertilised upland pasture

    DEFF Research Database (Denmark)

    Klumpp, Katja; Bloor, Juliette M. G.; Ambus, Per

    2011-01-01

    that clover density had indirect effects on the sensitivity of N2O emissions to abiotic and biotic factors possibly via changes in soil pH. Overall, our results suggest that spatial heterogeneity in clover abundance may have relatively little impact on field-scale N2O emissions in fertilized grasslands.......-labelled fertilizer application and automatic chamber measurements was used to investigate N2O fluxes and soil-plant N transfers for high- and low-density clover patches in an intensively-managed, upland pasture (Auvergne, France) over the course of one growing season. During the six-month study period, N2O fluxes...... 15N-labelled fertilizer peaked at 40% shortly after fertilizer application, but the dominant source of N2O fluxes was the soil N pool. Contrary to expectations, clover density had no significant effects on N content or patterns of 15N recovery in plant or soil mineral N pools. Nevertheless, we found...

  13. Insight into effects of mature compost recycling on N2O emission and denitrification genes in sludge composting.

    Science.gov (United States)

    Wang, Ke; Wu, Yiqi; Li, Weiguang; Wu, Chuandong; Chen, Zhiqiang

    2018-03-01

    Mature compost recycling is widely used to reduce the dosage of organic bulking agent in actual composting process. In this study, the effects of mature compost amendment on N 2 O emission and denitrification genes were investigated in 47 days composting of sewage sludge and rice husks. The results showed that mature compost amendment dramatically augmented N 2 O emission rate in mesophilic phase and CO 2 emission rate in thermophilic phase of composting, respectively. The cumulative amount of N 2 O emission increased by more than 23 times compared to the control. Mature compost amendment not only reduced moisture and pH, but also significantly increased NO 3 - -N and NO 2 - -N concentrations. The correlation matrices indicated that NO 3 - -N, narG and norB were the main factors influencing N 2 O emission rate in sludge composting with mature compost recycling, but the N 2 O emission rate was significantly correlated to NO 2 - -N, nirK and norB in the control. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. Effects of coastal marsh conversion to shrimp aquaculture ponds on CH4 and N2O emissions

    Science.gov (United States)

    Yang, P.; Bastviken, D.; Lai, D. Y. F.; Jin, B. S.; Mou, X. J.; Tong, C.; Yao, Y. C.

    2017-12-01

    In this study, we compared the CH4 and N2O fluxes from a tidal brackish Cyperus malaccensis marsh ecosystem and nearby shrimp ponds, converted from C. malaccensis marsh in the last 3-4 years, in the Min River estuary of southeast China over the aquaculture period of the year. Significant differences in CH4 and N2O fluxes were observed in space (between brackish marsh and shrimp ponds) and in time (between sampling occasions that were distributed over the aquaculture period). CH4 fluxes from the shrimp ponds were on an average 10-fold higher than from the brackish marsh. N2O emissions, on the other hand, were lower from the shrimp pond (25% of the emissions from the brackish marsh). Accessory data indicates that these patterns were primarily linked to water level variability and temperature (all fluxes), sediment porewater sulfate concentrations (CH4 flux) and total nitrogen concentrations (N2O flux). Our research demonstrates that the coastal marsh ecosystem converted to aquaculture ponds considerably alter emissions of CH4 and N2O and provides input to the global discussion on how to account for emissions from various types of flooded land in greenhouse gas inventories.

  15. Production of N2O5and ClNO2through Nocturnal Processing of Biomass-Burning Aerosol.

    Science.gov (United States)

    Ahern, Adam T; Goldberger, Lexie; Jahl, Lydia; Thornton, Joel; Sullivan, Ryan C

    2018-01-16

    Biomass burning is a source of both particulate chloride and nitrogen oxides, two important precursors for the formation of nitryl chloride (ClNO 2 ), a source of atmospheric oxidants that is poorly prescribed in atmospheric models. We investigated the ability of biomass burning to produce N 2 O 5 (g) and ClNO 2 (g) through nocturnal chemistry using authentic biomass-burning emissions in a smog chamber. There was a positive relationship between the amount of ClNO 2 formed and the total amount of particulate chloride emitted and with the chloride fraction of nonrefractory particle mass. In every fuel tested, dinitrogen pentoxide (N 2 O 5 ) formed quickly, following the addition of ozone to the smoke aerosol, and ClNO 2 (g) production promptly followed. At atmospherically relevant relative humidities, the particulate chloride in the biomass-burning aerosol was rapidly but incompletely displaced, likely by the nitric acid produced largely by the heterogeneous uptake of N 2 O 5 (g). Despite this chloride acid displacement, the biomass-burning aerosol still converted on the order of 10% of reacted N 2 O 5 (g) into ClNO 2 (g). These experiments directly confirm that biomass burning is a potentially significant source of atmospheric N 2 O 5 and ClNO 2 to the atmosphere.

  16. Populasi dan aktivitas denitrifikasi serta emisi gas N2 O pada lahan pertanian organik, pertanian intensif, dan hutan

    Directory of Open Access Journals (Sweden)

    Dwi Agustiyani

    2012-10-01

    Full Text Available This research investigate the population and potentials denitrification activity from three different soils, organically farmed soil, intensive farmed soil and forest soil. Our objectives were to explore spatial gradients in denitrifier populations, examine whether populations density and its potential activity was related to soil chemical properties (C and N content, and determine the potential emission of gas N2O. Results indicated biological functional differences between these three different soil ecosystems. Forest soil had the highest population density of denitrifying bacteria and also had significant potential denitrifying activities. The highest potentials denitrifying activity in the soil affected to the lowest emission of N2O gas. The lowest population and potential denitrifying activity was measured in the intensive farmed soil. Those conditions might be promoted the potentials emission of N2O.

  17. Ground and canopy soil N2O fluxes from smallholder oil palm plantations following deforestation in Sumatra, Indonesia

    Science.gov (United States)

    Hassler, Evelyn; Corre, Marife D.; Kurniawan, Syahrul; Allen, Kara; Veldkamp, Edzo

    2017-04-01

    Due to an increasing global demand in cheap oils and biofuels, forest conversion to oil palm plantations is rapidly increasing in Indonesia. Although forest conversion is known to influence soil N2O fluxes, measurements from oil palm are scarce. Our study aimed to (1) quantify changes in soil N2O fluxes with forest conversion to oil palm plantations, (2) quantify the contribution of oil-palm canopy soil (lodged between the stems and leaf axils) to N2O fluxes, and (3) determine their controlling factors. In Jambi, Sumatra, we selected two landscapes that mainly differed in soil texture but both on heavily weathered soils: loam and clay Acrisol soils. Within each landscape, we investigated lowland forest, jungle rubber (rubber trees interspersed in secondary forest), both as the reference (previous) land uses, and the converted oil palm plantations by smallholders. Each land use had four replicate plots within each landscape. Each replicate plot had four permanently placed chambers, and soil N2O fluxes were measured monthly from December 2012 to December 2013 by placing vented static covers on chamber bases for 30 minutes for gas flux measurement. For oil-palm canopy soil, each replicate plot was represented by five oil palms, and each oil palm stem was delineated into three 1-m sections (low, middle, and top) in order to represent possible gradients of canopy soil conditions that influence N2O fluxes. Measurements were conducted from February 2013 to May 2014 by collecting canopy soil from each stem section and incubating it in-situ in an air-tight glass jar. Land-use conversion to smallholder plantations had no effect on soil N-oxide fluxes (P = 0.58 to 0.76) due to the inherently low soil N availability and the low N fertilization rates (commonly 48 to 88 kg N ha-1 yr-1) of smallholder oil palm plantations. Soil N2O fluxes (kg N ha-1 yr-1) were: 0.6 ± 0.1 to 1.2 ± 0.6 from the reference land uses and 1.0 ± 0.2 to 1.1 ± 0.5 from the smallholder oil palm

  18. Tall tower landscape scale N2O flux measurements in a Danish agricultural and urban, coastal area

    Science.gov (United States)

    Ibrom, Andreas; Lequy, Émeline; Loubet, Benjamin; Pilegaard, Kim; Ambus, Per

    2015-04-01

    Both technical and natural processes emit the greenhouse gas nitrous oxide (N2O) into the atmosphere. The abundant use of nitrogen (N) as fertiliser increases the concentration of reactive nitrogen (Nr) in the atmosphere, the hydrosphere and in the biosphere, i.e. in terrestrial and aquatic ecosystems. Surplus Nr is distributed across linkages to other spheres until most of it is emitted to the atmosphere as NO, N2O or N2. A complete estimate of the effects from human activities on N2O emissions must therefore include all emissions, the direct emissions and the indirect emissions that happen in interlinked spheres. For this it is necessary to assess the fluxes at least at the landscape scale. The episodic nature and the large spatial variability make it difficult to estimate the direct and indirect emissions in a landscape. Modelling requires not only to include the highly variable microbial processes in the ecosystems that produce N2O but as well the accurate simulation of lateral Nr fluxes and their effects on N2O fluxes in places remote from the primary Nr sources. In this context tall tower N2O flux measurements are particularly useful as they integrate over larger areas and can be run, continuously without disturbing the fluxes. On the other hand these measurements can be difficult to interpret due to difficulties to measure the small concentration fluctuations in the atmosphere at small flux rates and to accurately attribute the measured flux at the tower to the area that generates the flux, i.e. the source area. The Technical University of Denmark (DTU) has established eddy covariance N2O flux measurements on a 125 m tall tower at its Risø Campus as part of the EU research infrastructure project the 'Integrated non-CO2 Greenhouse gas Observing System' (InGOS). The eddy covariance system consisted of a N2O/CO quantum cascade laser, Los Gatos, Mountain View, CA, USA and a 3D sonic anemometer (USA-1), Metek, Elmshorn, Germany. The Risø peninsula lies at the

  19. Effects of cattle slurry and nitrification inhibitor application on spatial soil O2 dynamics and N2O production pathways

    DEFF Research Database (Denmark)

    Nguyen, Quan Van; Wu, Di; Kong, Xianwang

    2017-01-01

    Application of cattle slurry to grassland soil has environmental impacts such as ammonia volatilization and greenhouse gas emissions. The extent, however, depends on application method and soil conditions through their effects on infiltration and oxygen (O2) availability during subsequent...... decomposition. Here, we applied O2 planar optode and N2O isotopomer techniques to investigate the linkage between soil O2 dynamics and N2O production pathways in soils treated with cattle slurry (treatment CS) and tested the effect of the nitrification inhibitor 3,4-dimethyl pyrazole phosphate, DMPP (treatment...... produced during incubation. Over 18 days, the application of DMPP substantially mitigated N2O emissions by 60% compared to untreated CS in the investigated system which in terms of aeration status corresponded to wet or compacted grassland soil. Using this novel combination of O2 planar optode imaging...

  20. Effects of green manure storage and incorporation methods on nitrogen release and N2O emissions after soil application

    DEFF Research Database (Denmark)

    Carter, Mette Sustmann; Sørensen, Peter; Petersen, Søren O.

    2014-01-01

    of plant-available N, nitrous oxide (N2O) fluxes, and soil respiration. Grass-clover silage provided the highest net N release with similar results for the two incorporation methods. Up to one third of the total N content in silage became plant-available during the three months. In contrast, no net N......More efficient use of green manure-derived nitrogen (N) may improve crop yields and reduce environmental impacts in stockless organic arable farming. In this 3-month incubation study, we tested a new strategy where green manure leys are harvested and preserved until the following spring either...... total N. Possibly N2O production via denitrification was stimulated by oxygen-limited conditions near the decomposing silage. In contrast, compost incorporated by harrowing caused net N2O uptake, presumably an effect of reduced mineral N availability in this treatment. Overall, our study revealed...

  1. [Evaluation of N2O inhalation and oral midazolam conscious sedation in pediatric dentistry of children with intellectual disability].

    Science.gov (United States)

    Tian, Xiao-hua; Yang, Yan-zhong; Li, Xiao-feng

    2015-06-01

    To evaluate the effect of N2O inhalation and oral midazolam sedation on uncooperative patients with intellectual disability in pediatric dentistry. N2O inhalation (35%-50%) and oral midazolam conscious sedation (dosages range: 0.50-0.75 mg/kg) were applied to 67 uncooperative pediatric patients with intellectual disability in outpatient department. The patients were divided into 2 groups: group A (N2O inhalation conscious sedation) and group B(oral midazolam conscious sedation).Treatment results and safety were statistically analyzed by Chi-square test with SPSSl3.0 software package. The mean success rate was 70%. The success rate in group B (75%) was higher than group A (67%). The overall incidence of adverse reactions was 13%(9/67). The adverse reaction rate in group B (25%) was significantly higher than group A (5%, Ppediatric dental uncooperative patients with intellectual disability.

  2. The role of N2O derived from crop-based biofuels, and from agriculture in general, in Earth's climate

    Science.gov (United States)

    Smith, Keith A.; Mosier, Arvin R.; Crutzen, Paul J.; Winiwarter, Wilfried

    2012-01-01

    In earlier work, we compared the amount of newly fixed nitrogen (N, as synthetic fertilizer and biologically fixed N) entering agricultural systems globally to the total emission of nitrous oxide (N2O). We obtained an N2O emission factor (EF) of 3–5%, and applied it to biofuel production. For ‘first-generation’ biofuels, e.g. biodiesel from rapeseed and bioethanol from corn (maize), that require N fertilizer, N2O from biofuel production could cause (depending on N uptake efficiency) as much or more global warming as that avoided by replacement of fossil fuel by the biofuel. Our subsequent calculations in a follow-up paper, using published life cycle analysis (LCA) models, led to broadly similar conclusions. The N2O EF applies to agricultural crops in general, not just to biofuel crops, and has made possible a top-down estimate of global emissions from agriculture. Independent modelling by another group using bottom-up IPCC inventory methodology has shown good agreement at the global scale with our top-down estimate. Work by Davidson showed that the rate of accumulation of N2O in the atmosphere in the late nineteenth and twentieth centuries was greater than that predicted from agricultural inputs limited to fertilizer N and biologically fixed N (Davidson, E. A. 2009 Nat. Geosci. 2, 659–662.). However, by also including soil organic N mineralized following land-use change and NOx deposited from the atmosphere in our estimates of the reactive N entering the agricultural cycle, we have now obtained a good fit between the observed atmospheric N2O concentrations from 1860 to 2000 and those calculated on the basis of a 4 per cent EF for the reactive N. PMID:22451102

  3. The role of N2O derived from crop-based biofuels, and from agriculture in general, in Earth's climate.

    Science.gov (United States)

    Smith, Keith A; Mosier, Arvin R; Crutzen, Paul J; Winiwarter, Wilfried

    2012-05-05

    In earlier work, we compared the amount of newly fixed nitrogen (N, as synthetic fertilizer and biologically fixed N) entering agricultural systems globally to the total emission of nitrous oxide (N(2)O). We obtained an N(2)O emission factor (EF) of 3-5%, and applied it to biofuel production. For 'first-generation' biofuels, e.g. biodiesel from rapeseed and bioethanol from corn (maize), that require N fertilizer, N(2)O from biofuel production could cause (depending on N uptake efficiency) as much or more global warming as that avoided by replacement of fossil fuel by the biofuel. Our subsequent calculations in a follow-up paper, using published life cycle analysis (LCA) models, led to broadly similar conclusions. The N(2)O EF applies to agricultural crops in general, not just to biofuel crops, and has made possible a top-down estimate of global emissions from agriculture. Independent modelling by another group using bottom-up IPCC inventory methodology has shown good agreement at the global scale with our top-down estimate. Work by Davidson showed that the rate of accumulation of N(2)O in the atmosphere in the late nineteenth and twentieth centuries was greater than that predicted from agricultural inputs limited to fertilizer N and biologically fixed N (Davidson, E. A. 2009 Nat. Geosci. 2, 659-662.). However, by also including soil organic N mineralized following land-use change and NO(x) deposited from the atmosphere in our estimates of the reactive N entering the agricultural cycle, we have now obtained a good fit between the observed atmospheric N(2)O concentrations from 1860 to 2000 and those calculated on the basis of a 4 per cent EF for the reactive N.

  4. Effects of pasture management on N2O and NO emissions from soils in the humid tropics of Costa Rica

    Science.gov (United States)

    Veldkamp, Edzo; Keller, Michael; NuñEz, Marvin

    1998-03-01

    Emissions of nitrous oxide (N2O) and nitric oxide (NO) from agricultural soils in the tropics are important in the global budgets of these trace gases. We made monthly measurements of N2O and NO emissions from pastures with three different management systems on volcanic soils in northwestern Costa Rica: traditional (no N input from fertilizer or legumes), pastures with a grass-legume combination, and pastures fertilized with 300 kg N ha-11 yr-1. Average annual N2O emissions were 2.7 ng N cm-2 h-1 from the traditional pastures, 4.9 ng N cm-2 h-1 from the grass-legume pastures, and 25.8 ng N cm-2 h-1 from the fertilized pastures. Average annual NO emissions were 0.9, 1.3, and 5.3 ng N cm-2 h-1 from traditional, grass-legume and fertilized pastures, respectively. In a separate experiment the effects of ammonium, nitrate, and urea-based fertilizer mixtures on nitrogen oxide fluxes were compared. We measured nitrogen oxide fluxes following four different fertilization events. Nitrogen oxide fluxes were among the highest ever measured. The difference in soil water content between the fertilization events had a far greater effect on N2O and NO emissions than the effect of fertilizer composition. We conclude that the concept of "emission factors" for calculating N2O and NO emissions from different types of N fertilizer is flawed because environmental factors are more important than the type of N fertilizer. To estimate fertilizer-induced N2O emission in tropical agriculture, stratification according to soil moisture regime is more useful than stratification according to fertilizer composition.

  5. Long-term spatiotemporal patterns of CH4 and N2O emissions from livestock and poultry production in Turkey.

    Science.gov (United States)

    Kulcu, Recep; Ekinci, Kamil; Evrendilek, Fatih; Ertekin, Can

    2010-08-01

    This study quantified spatiotemporal patterns of CH4 and N2O emissions from livestock and poultry production in Turkey between 1961 and 2007. CH4(enteric) (from enteric fermentation), CH4(manure) (from manure management), and N2O(AWM) (from animal waste management) emissions in Turkey were estimated at 1,164, 216, and 55 Gg in 1961 and decreased to 844, 187, and 39 Gg in 2007, contributing a share of roughly 2% to the global livestock-related CH4 emissions and %1.5 to the global N2O(AWM) emissions, respectively. Total CO2-eq emissions were estimated at 50.7 Tg in 1961 and declined from a maximum value of 60.7 Tg in 1982 to a minimum value of 34.5 Tg in 2003, with a mean emission rate of 48 Tg year(-1) due to a significant reduction in the number of ruminant livestock. The highest mean share of emissions belonged to West Black Sea (14% and 16%) for CH4(enteric) and CH4(manure) and to North East Anatolia (12% and %13) for N2O(AWM) and total CO2-eq emissions, respectively. The highest emission density was 1.7 Mg km(-2) year(-1) for CH4(enteric), 0.3 Mg km(-2) year(-1) for CH4(manure), and 0.07 Mg km(-2) year(-1) for the total CO2-eq emissions in the West and North East Anatolia regions and 0.09 Mg km(-2) year(-1) for N2O(AWM) in the East Marmara region. Temporal and spatial variations in CH4(enteric), CH4(manure), and N2O(AWM) emissions in Turkey were estimated using regression models and ordinary kriging at a 500-m resolution, respectively.

  6. Active species in a large volume N2-O2 post-discharge reactor

    International Nuclear Information System (INIS)

    Kutasi, K; Pintassilgo, C D; Loureiro, J; Coelho, P J

    2007-01-01

    A large volume post-discharge reactor placed downstream from a flowing N 2 -O 2 microwave discharge is modelled using a three-dimensional hydrodynamic model. The density distributions of the most populated active species present in the reactor-O( 3 P), O 2 (a 1 Δ g ), O 2 (b 1 Σ g + ), NO(X 2 Π), NO(A 2 Σ + ), NO(B 2 Π), NO 2 (X), O 3 , O 2 (X 3 Σ g - ) and N( 4 S)-are calculated and the main source and loss processes for each species are identified for two discharge conditions: (i) p = 2 Torr, f = 2450 MHz, and (ii) p = 8 Torr, f = 915 MHz; in the case of a N 2 -2%O 2 mixture composition and gas flow rate of 2 x 10 3 sccm. The modification of the species relative densities by changing the oxygen percentage in the initial gas mixture composition, in the 0.2%-5% range, are presented. The possible tuning of the species concentrations in the reactor by changing the size of the connecting afterglow tube between the active discharge and the large post-discharge reactor is investigated as well

  7. Rayleigh-Brillouin light scattering spectroscopy of nitrous oxide (N2O)

    Science.gov (United States)

    Wang, Y.; Liang, K.; van de Water, W.; Marques, W.; Ubachs, W.

    2018-02-01

    High signal-to-noise and high-resolution light scattering spectra are measured for nitrous oxide (N2O) gas at an incident wavelength of 403.00 nm, at 90° scattering, at room temperature and at gas pressures in the range 0.5 - 4 bar. The resulting Rayleigh-Brillouin light scattering spectra are compared to a number of models describing in an approximate manner the collisional dynamics and energy transfer in this gaseous medium of this polyatomic molecular species. The Tenti-S6 model, based on macroscopic gas transport coefficients, reproduces the scattering profiles in the entire pressure range at less than 2% deviation at a similar level as does the alternative kinetic Grad's 6-moment model, which is based on the internal collisional relaxation as a decisive parameter. A hydrodynamic model fails to reproduce experimental spectra for the low pressures of 0.5-1 bar, but yields very good agreement ( viscosity of ηb ∼(6 ± 2) ×10-5 Pa · s. A 'rough-sphere' model, previously shown to be effective to describe light scattering in SF6 gas, is not found to be suitable, likely in view of the non-sphericity and asymmetry of the N-N-O structured linear polyatomic molecule.

  8. Temperature dependent halogen activation by N2O5 reactions on halide-doped ice surfaces

    Directory of Open Access Journals (Sweden)

    J. A. Thornton

    2012-06-01

    Full Text Available We examined the reaction of N2O5 on frozen halide salt solutions as a function of temperature and composition using a coated wall flow tube technique coupled to a chemical ionization mass spectrometer (CIMS. The molar yield of photo-labile halogen compounds was near unity for almost all conditions studied, with the observed reaction products being nitryl chloride (ClNO2 and/or molecular bromine (Br2. The relative yield of ClNO2 and Br2 depended on the ratio of bromide to chloride ions in the solutions used to form the ice. At a bromide to chloride ion molar ratio greater than 1/30 in the starting solution, Br2 was the dominant product otherwise ClNO2 was primarily produced on these near pH-neutral brines. We demonstrate that the competition between chlorine and bromine activation is a function of the ice/brine temperature presumably due to the preferential precipitation of NaCl hydrates from the brine below 250 K. Our results provide new experimental confirmation that the chemical environment of the brine layer changes with temperature and that these changes can directly affect multiphase chemistry. These findings have implications for modeling air-snow-ice interactions in polar regions and likely in polluted mid-latitude regions during winter as well.

  9. Characterization of the N2O-producing soil bacterium Rhizobium azooxidifex sp. nov.

    Science.gov (United States)

    Behrendt, Undine; Kämpfer, Peter; Glaeser, Stefanie P; Augustin, Jürgen; Ulrich, Andreas

    2016-06-01

    In the context of studying the bacterial community involved in nitrogen transformation processes in arable soils exposed to different extents of erosion and sedimentation in a long-term experiment (CarboZALF), a strain was isolated that reduced nitrate to nitrous oxide without formation of molecular nitrogen. The presence of the functional gene nirK, encoding the respiratory copper-containing nitrite reductase, and the absence of the nitrous oxide reductase gene nosZ indicated a truncated denitrification pathway and that this bacterium may contribute significantly to the formation of the important greenhouse gas N2O. Phylogenetic analysis based on the 16S rRNA gene sequence and the housekeeping genes recA and atpD demonstrated that the investigated soil isolate belongs to the genus Rhizobium. The closest phylogenetic neighbours were the type strains of Rhizobium. subbaraonis and Rhizobium. halophytocola. The close relationship with R. subbaraonis was reflected by similarity analysis of the recA and atpD genes and their amino acid positions. DNA-DNA hybridization studies revealed genetic differences at the species level, which were substantiated by analysis of the whole-cell fatty acid profile and several distinct physiological characteristics. Based on these results, it was concluded that the soil isolate represents a novel species of the genus Rhizobium, for which the name Rhizobium azooxidifex sp. nov. (type strain Po 20/26T=DSM 100211T=LMG 28788T) is proposed.

  10. Temperature dependent halogen activation by N2O5 reactions on halide-doped ice surfaces

    Science.gov (United States)

    Lopez-Hilfiker, F. D.; Constantin, K.; Kercher, J. P.; Thornton, J. A.

    2012-06-01

    We examined the reaction of N2O5 on frozen halide salt solutions as a function of temperature and composition using a coated wall flow tube technique coupled to a chemical ionization mass spectrometer (CIMS). The molar yield of photo-labile halogen compounds was near unity for almost all conditions studied, with the observed reaction products being nitryl chloride (ClNO2) and/or molecular bromine (Br2). The relative yield of ClNO2 and Br2 depended on the ratio of bromide to chloride ions in the solutions used to form the ice. At a bromide to chloride ion molar ratio greater than 1/30 in the starting solution, Br2 was the dominant product otherwise ClNO2 was primarily produced on these near pH-neutral brines. We demonstrate that the competition between chlorine and bromine activation is a function of the ice/brine temperature presumably due to the preferential precipitation of NaCl hydrates from the brine below 250 K. Our results provide new experimental confirmation that the chemical environment of the brine layer changes with temperature and that these changes can directly affect multiphase chemistry. These findings have implications for modeling air-snow-ice interactions in polar regions and likely in polluted mid-latitude regions during winter as well.

  11. Wave Driven N2-O2 Discharges as Sources of Active Species

    Science.gov (United States)

    Henriques, J.; Tatarova, E.; Ferreira, Cm.; Ricard, A.

    2003-10-01

    Microwave N2-O2 discharges driven by traveling surface waves attract attention as sources of active species, in particular for cold plasma sterilization of surgical material and other medical devices. The objective of this study is to investigate the concentration of various active species, such as O(3P) and N(4S) atoms, N2+ ions, and N2(A) and NO(A) molecules, as a function of the spatial position and the mixture composition in an azimuthally symmetric surface wave driven discharge operating at 2.45 GHz. The plasma column is created in N2-xO2 mixtures (x < 10%) at the pressure p = 5 Torr, in a quartz glass tube with inner radius a = 0.25 cm and with flow rates in the range Q = 300 -1000 sccm. Emission spectroscopy is used to measure the N2(1+,2+, 1-) and NO(γ,β) band intensities along the discharge column length. NO titration is used to determine the densities of N and O atoms in the post-discharge, close to the end of the discharge. A theoretical model is developed which accounts in a self-consistent way for the electron and heavy particle kinetics, gas thermal balance and wave electrodynamics. This model provides a satisfactory interpretation of the experimental data.

  12. PEMBUATAN AYAKAN MOLEKULER BERBASIS KARBON UNTUK PEMISAHAN N2/O2 DARI PIROLISIS RESIN PHENOL FORMALDEHYDE

    Directory of Open Access Journals (Sweden)

    Imam Prasetyo

    2012-02-01

    Full Text Available Proses pemisahan campuran gas dengan menggunakan carbon molecular sieve (CMS atau ayakan molekuler berbasis karbon merupakan teknologi proses pemisahan yang mulai banyak diterapkan di dalam industri kimia. Dalam penelitian ini, CMS untuk pemisahan N2 dari udara dibuat dari pirolisis bahan polimer sintetis yaitu resin phenol formaldehyde (PF. Prekursor yang berupa resin tersebut dipanaskan dalam retort pada suhu 400-950oC selama 0,5-3 jam yang disertai dengan pengaliran gas N2 ke dalam retort dengan laju 100 mL/jam. Dengan proses pirolisis, atom-atom non-karbon penyusun bahan polimer akan terurai dan menguap sehingga hanya menyisakan arang karbon dengan struktur kerangka atom karbon yang sesuai dengan struktur kerangka dasar rantai polimer. Kemudian karbon hasil prolisis tersebut dipanaskan lebih lanjut pada suhu 750-950oC sambil dialiri gas CO2 selama 1 jam. Pada kondisi ini karbon akan mengalami proses gasifikasi parsial sehingga terbentuk karbon dengan porositas tinggi. Melalui rekayasa proses polimerisasi dan karbonisasi dihasilkan material karbon berpori yang mayoritas porinya adalah mikropori dengan ukuran pori efektif < 2 nm yang dapat dikategorikan sebagai CMS yang dapat dipergunakan untuk memisahkan campuran gas N2-O2.  Pada penelitian ini dihasilkan CMS dengan selektifitas kinetis DN2/DO2 sekitar 3.

  13. Fourier transform infrared studies of the N2-O2 binary system

    International Nuclear Information System (INIS)

    Minenko, M.; Jodi, H.-J.

    2006-01-01

    Solid solutions (N 2 ) x (O 2 ) 1-x have been investigated by infrared absorption measurements mainly in the O 2 and N 2 stretching regions, between 60-10 K, completing former similar studies by Raman scattering. We produced thermodynamically stable samples by a careful thermal treatment, followed by cooling/heating cycles over weeks, during which we took spectra. From fingerprints in the infrared spectra we deduce phase-transition and solubility lines and suggest a refined, improved T-x % phase diagram in respect to the inconsistencies between those in the literature. The spectra of N 2 -O 2 mixtures are pretty complex, but by referring to known spectra of the pure systems N 2 or O 2 we were able to assign and interpret broad (∼100 cm - 1 ) phonon side bands to fundamentals and an electronic transition (O 2 ), depending on actual temperature and concentration. Narrow features in the spectra ( -1 ) were attributed to the vibron DOS of N 2 or O 2 , whose bandwidth, band shape, and intensity are different and characteristic for each phase. Differences between pure and mixed systems are pointed out. The matrix isolation technique (2 ppm of CO) was used to probe our mixture

  14. N2O4 as a working substance for a spacecraft power plant

    International Nuclear Information System (INIS)

    Popyrin, L.S.; Starostenko, N.N.; Starostenko, V.I.

    1975-01-01

    A gas turbine cycle on dissociating nitrogen tetroxide (N 2 O 4 ) as working medium is considered. Nitrogen tetroxide has a number of properties advantageous in this respect. A direct cycle power plant is considered. A fast reactor with a gas coolant is an energy source. Some versions of a power plant have been analysed for the gas temperature at the turbine inlet ranging from 1170 to 1470 K. The cycle efficiency is found to increase considerably with the working medium temperature rise at the turbine inlet only to 1380-1400 K. To determine the efficiency of the plants of this type, they are compared to identical designs of gas and gas-liquid cycles on alkali metals, inert gases and dissociating phosphorus. Theoretical and experimental data show that the turbine with nitrogen tetroxide as working medium is more compact in comparison to that with inert gases. Small specific surfaces of the radiator, small size of the turbine and thermal process equipment, and high efficiency are evidence of the advisability of using the plant of the type considered as on-board power plant of a space ship

  15. Intergenomic comparisons highlight modularity of the denitrification pathway and underpin the importance of community structure for N2O emissions.

    Directory of Open Access Journals (Sweden)

    Daniel R H Graf

    Full Text Available Nitrous oxide (N2O is a potent greenhouse gas and the predominant ozone depleting substance. The only enzyme known to reduce N2O is the nitrous oxide reductase, encoded by the nosZ gene, which is present among bacteria and archaea capable of either complete denitrification or only N2O reduction to di-nitrogen gas. To determine whether the occurrence of nosZ, being a proxy for the trait N2O reduction, differed among taxonomic groups, preferred habitats or organisms having either NirK or NirS nitrite reductases encoded by the nirK and nirS genes, respectively, 652 microbial genomes across 18 phyla were compared. Furthermore, the association of different co-occurrence patterns with enzymes reducing nitric oxide to N2O encoded by nor genes was examined. We observed that co-occurrence patterns of denitrification genes were not randomly distributed across taxa, as specific patterns were found to be more dominant or absent than expected within different taxonomic groups. The nosZ gene had a significantly higher frequency of co-occurrence with nirS than with nirK and the presence or absence of a nor gene largely explained this pattern, as nirS almost always co-occurred with nor. This suggests that nirS type denitrifiers are more likely to be capable of complete denitrification and thus contribute less to N2O emissions than nirK type denitrifiers under favorable environmental conditions. Comparative phylogenetic analysis indicated a greater degree of shared evolutionary history between nosZ and nirS. However 30% of the organisms with nosZ did not possess either nir gene, with several of these also lacking nor, suggesting a potentially important role in N2O reduction. Co-occurrence patterns were also non-randomly distributed amongst preferred habitat categories, with several habitats showing significant differences in the frequencies of nirS and nirK type denitrifiers. These results demonstrate that the denitrification pathway is highly modular, thus

  16. Post-harvest N2O emissions were not affected by various types of oilseed straw incorporated into soil

    Science.gov (United States)

    Köbke, Sarah; Senbayram, Mehmet; Hegewald, Hannes; Christen, Olaf; Dittert, Klaus

    2015-04-01

    Oilseed rape post-harvest N2O emissions are seen highly critical as so far they are considered as one of the most crucial drawbacks in climate-saving bioenergy production systems. N2O emissions may substantially counterbalance the intended savings in CO2 emissions. Carbon-rich crop residues in conjunction with residual soil nitrate are seen as a key driver since they may serve as energy source for denitrification and, they may alter soil-borne N2O emissions. As oilseed rape straw is known to have high N/C ratio compared to other crop residues, its soil incorporation may specifically trigger post-harvest N2O emissions. Therefore, the aim of the present study was to determine post-harvest N2O emissions in soils amended with various types of oilseed rape straw (with different N/C ratio) and barley straw in field and incubation experiments. In the incubation experiment, oilseed rape or 15N labelled barley straw were mixed with soil at a rate of 1.3 t DM ha-1 and studied for 43 days. Treatments consisted of non-treated control soil (CK), 15N labelled barley straw (BST), oilseed rape straw (RST), 15N labelled barley straw + N (BST+N), or oilseed rape straw + N (RST+N). N fertilizer was applied to the soil surface as ammonium-nitrate at a rate of 100 kg N ha-1 and soil moisture was adjusted to 80% water-holding capacity. In the field experiment, during the vegetation period 15N labelled fertilizer (15NH415NO3) was used to generate 15N labelled oilseed rape straw (up to 5 at%). Here, the three fertilizer treatments consisted of 5 kg N ha-1 (RST-5), 150 kg N ha-1 (RST-150) and 180 kg N ha-1 (RST-180). Post-harvest N2O emissions were determined during the period of August 2013 to February 2014 by using static flux chambers. In the incubation trial, cumulative N2O emissions were 5, 29, 40 g N2O-N ha-1 148 days-1 in non-fertilized control, BST and RST treatments, respectively. Here, emissions were slightly higher in RST than BST (p

  17. Source identification of N2O produced during simulated wastewater treatment under different oxygen conditions using stable isotopic analysis

    Directory of Open Access Journals (Sweden)

    T Azzaya

    2014-12-01

    Full Text Available Nitrous oxide (N2O, a potent greenhouse gas which is important in climate change, is predicted to be the most dominant ozone depleting substance. It is mainly produced by oxidation of hydroxylamine (NH2OH or reduction of nitrite (NO2- during microbiological processes such as nitrification and denitrification. Wastewater treatment plant (WWTP is one of the anthropogenic N2O sources because inorganic and organic nitrogen compounds are converted to nitrate (NO3-, in the case of standard system or N2 (in the case of advanced system by bacterial nitrification and denitrification in WWTP. We investigated the N2O production mechanisms during batch experiments that simulate wastewater treatment with activated sludge under various dissolved oxygen (DO concentrations by stable isotope analysis. About 125mL of water was sampled from 30L incubation chamber for several times during the incubation, and concentration and isotopomer ratios of N2O and N-containing species were measured using gas chromatography/isotope ratio mass spectrometry (GC/IRMS. Ammonium (NH4+ consumption was accompanied by increment of nitrite (NO2-, and at the same time dissolved N2O concentration gradually increased to 4850 and 5650 nmol kg-1, respectively, during the four-hour incubation when DO concentrations were 0.2 and 0.5 mg L-1. Observed low SP values (0.2-8.9‰ at DO-0.2 mg L-1, -5.3-6.3‰ at DO-0.5 mg L-1, -1.0-8.3‰ at DO-0.8 mg L-1 in N2O and relationship of nitrogen isotope ratios between N2O and its potential substrates (NH4+, NO3- suggested that N2O produced under the aerobic condition derived mainly from NO2- reduction by ammonia-oxidizing bacteria (nitrifier–denitrification.DOI: http://doi.dx.org/10.5564/mjc.v15i0.313Mongolian Journal of Chemistry  15 (41, 2014, p4-10  

  18. Problems of creating fuel elements for fast gas-cooled reactors working on N2O4-dissociating coolant

    International Nuclear Information System (INIS)

    Nesterenko, V.B.; Zelensky, V.F.; Kolykhan, L.I.; Karpenko, G.V.; Krasnorutsky, V.S.; Isakov, V.P.; Ashikhmin, V.P.; Permyakov, L.N.

    1985-01-01

    A variant of fast gas-cooled reactors is one using dissociating N 2 O 4 nitrogen tetroxide as a coolant. This type of reactors is promising because of great thermal effects of dissociation reactions while heating and recombination while cooling; small latent heat of evaporation; high heat transfer coefficient owing to additional heat transfer in a chemical reaction; high N 2 O 4 density in a gas state at operation parameters. The mentioned advantages give possibility to create a small turbine, heat exchange apparatus and to get high heat production in the active zone. All this opens new ways to increase power plants effectiveness

  19. Quantum Cascade Laser Measurements of Line Intensities, N2-, O2- and Ar- Collisional Broadening Coefficients of N2O in the  3 Band Near 4.5  m

    KAUST Repository

    Es-sebbar, E.-t.

    2016-04-19

    This study deals with precise measurements of absolute line intensities, N2-, O2- and Ar- collisional broadening coefficients of N2O in the P-branch of the ν3 vibrational band near 4.5 μm. Collisional broadening coefficients of N2O-air are derived from the N2- and O2- broadening contributions by considering an ideal atmospheric composition. Studies are performed at room temperature for 10 rotational transitions over 2190-2202 cm-1 spectral range using a distributed-feedback quantum cascade laser. To retrieve spectroscopic parameters for each individual transition, measured absorption line shape is simulated within Voigt and Galatry profiles. The obtained results compare well with previous experimental data available in the literature: the discrepancies being less than 4% for most of the probed transitions. The spectroscopic data reported here are very useful for the design of sensors used to monitor the abundance of N2O in earth\\'s atmosphere. © The Author(s) 2016.

  20. Quantum Cascade Laser Measurements of Line Intensities, N2-, O2- and Ar- Collisional Broadening Coefficients of N2O in the ν3 Band Near 4.5 µm.

    Science.gov (United States)

    Es-Sebbar, Et-Touhami; Deli, Meriem; Farooq, Aamir

    2016-06-01

    This study deals with precise measurements of absolute line intensities, N2-, O2- and Ar- collisional broadening coefficients of N2O in the P-branch of the ν3 vibrational band near 4.5 µm. Collisional broadening coefficients of N2O-air are derived from the N2- and O2- broadening contributions by considering an ideal atmospheric composition. Studies are performed at room temperature for 10 rotational transitions over 2190-2202 cm(-1) spectral range using a distributed-feedback quantum cascade laser. To retrieve spectroscopic parameters for each individual transition, measured absorption line shape is simulated within Voigt and Galatry profiles. The obtained results compare well with previous experimental data available in the literature: the discrepancies being less than 4% for most of the probed transitions. The spectroscopic data reported here are very useful for the design of sensors used to monitor the abundance of N2O in earth's atmosphere. © The Author(s) 2016.

  1. Potential impact of atmospheric N deposition on soil N2O emission varies with different soil N regimes

    Science.gov (United States)

    Kim, Y.; Yi, M.; Koike, T.

    2011-12-01

    Future increases in nitrogen (N) deposition has the potential to change belowground nutrient dynamics, especially N cycle, and thereby can alter the soil-atmosphere exchange of nitrous oxide (N2O) which is one of the major greenhouse gases. Moreover, we considered that their effect on soil N2O emission varies with different soil N levels because N2O is a by-product of the biological nitrification process in aerobic soil environments and of the biological denitrification process in anaerobic soil environments. To understand the changes in soil N2O flux under different soil N, we carried out simulated N addition experiment in three-year-old hybrid larch F1 (F1: Larix gmelinii var. japonica × Larix kaempferi) plantation during two growing seasons 2008 - 2009. The hybrid larch F1 was developed to make up for several problems of larch species, e.g. a high susceptibility to disease or grazing damage by insects and fungi, and a large number of this seedlings are planted recently in northern Japan. Based on soil analysis, we selected two sites which have different soil N concentration, i.e. low-N and high-N concentrations. Nitrogen input was initiated at the onset of our experiment, and included four treatments with four replications: Low-N soil + Zero-N control, Low-N soil + 50 kg-N addition, High-N soil + Zero-N control and High-N soil + 50 kg-N addition. The N was added as ammonium nitrate (NH4NO3) solution distributed in four occasions during each growing season. Gas and soil samples were taken from each plot on ten occasions at a time during each growing season. Collected N2O concentrations were determined by a gas chromatograph (GC-14B; Shimadzu, Kyoto, Japan) equipped with an electron capture detector, while total-N and inorganic-N concentrations were obtained by a NC analyzer (Sumigraph NC-1000; Sumica Chemical Analysis Service Ltd., Osaka, Japan) and an auto analyzer (AACS-4; BL-TEC Inc., Osaka, Japan), respectively. Before the N addition, initial total-N in High

  2. Co-Regulations of Spartina alterniflora Invasion and Exogenous Nitrogen Loading on Soil N2O Efflux in Subtropical Mangrove Mesocosms.

    Science.gov (United States)

    Jia, Dai; Qi, Fei; Xu, Xia; Feng, Jianxiang; Wu, Hao; Guo, Jiemin; Lu, Weizhi; Peng, Ronghao; Zhu, Xiaoshan; Luo, Yiqi; Lin, Guanghui

    2016-01-01

    Both plant invasion and nitrogen (N) enrichment should have significant impact on mangrove ecosystems in coastal regions around the world. However, how N2O efflux in mangrove wetlands responds to these environmental changes has not been well studied. Here, we conducted a mesocosm experiment with native mangrove species Kandelia obovata, invasive salt marsh species Spartina alterniflora, and their mixture in a simulated tide rotation system with or without nitrogen addition. In the treatments without N addition, the N2O effluxes were relatively low and there were no significant variations among the three vegetation types. A pulse loading of exogenous ammonium nitrogen increased N2O effluxes from soils but the stimulatory effect gradually diminished over time, suggesting that frequent measurements are necessary to accurately understand the behavior of N-induced response of N2O emissions. With the N addition, the N2O effluxes from the invasive S. alterniflora were lower than that from native K. obovata mesocosms. This result may be attributed to higher growth of S. alterniflora consuming most of the available nitrogen in soils, and thus inhibiting N2O production. We concluded that N loading significantly increased N2O effluxes, while the invasion of S. alterniflora reduced N2O effluxes response to N loading in this simulated mangrove ecosystem. Thus, both plant invasion and excessive N loading can co-regulate soil N2O emissions from mangrove wetlands, which should be considered when projecting future N2O effluxes from this type of coastal wetland.

  3. CH4 and N2O emissions embodied in international trade of meat

    International Nuclear Information System (INIS)

    Caro, Dario; Caldeira, Ken; LoPresti, Anna; Davis, Steven J; Bastianoni, Simone

    2014-01-01

    Although previous studies have quantified carbon dioxide emissions embodied in products traded internationally, there has been limited attention to other greenhouse gases such as methane (CH 4 ) and nitrous oxide (N 2 O). Following IPCC guidelines, we estimate non-CO 2 emissions from beef, pork and chicken produced in 237 countries over the period 1990–2010, and assign these emissions to the country where the meat is ultimately consumed. We find that, between 1990 and 2010, an average of 32.8 Mt CO 2 -eq emissions (using 100 year global warming potentials) are embodied in beef, pork and chicken traded internationally. Further, over the 20 year period, the quantity of CO 2 -eq emissions embodied in traded meat increased by 19%. The largest trade flows of emissions embodied in meat were from Brazil and Argentina to Russia (2.8 and 1.4 Mt of CO 2 -eq, respectively). Trade flows within the European region are also substantial: beef and pork exported from France embodied 3.3 Mt and 0.4 Mt of CO 2 -eq, respectively. Emissions factor of meat production (i.e. CO 2 -eq emissions per kg of meat) produced depend on ambient temperature, development level, livestock category (e.g. cattle, pork, and chicken) and livestock management practices. Thus, trade may result in an overall increase of GHG emissions when meat-consuming countries import meat from countries with a greater emissions intensity of meat production rather than producing the meat domestically. Comparing the emissions intensity of meat production of trading partners, we assess trade flows according to whether they tend to reduce or increase global emissions from meat production. (letter)

  4. Top-down estimates of European CH4 and N2O emissions based on four different inverse models

    NARCIS (Netherlands)

    Bergamaschi, P.; Corazza, M.; Karstens, U.; Athanassiadou, M.; Thompson, R.L.; Pison, I.; Manning, A.J.; Bousquet, P.; Segers, A.; Vermeulen, A.T.; Janssens-Maenhout, G.; Schmidt, M.; Ramonet, M.; Meinhardt, F.; Aalto, T.; Haszpra, L.; Moncrieff, J.; Popa, M.E.; Lowry, D.; Steinbacher, M.; Jordan, A.; O'Doherty, S.; Piacentino, S.; Dlugokencky, E.

    2015-01-01

    European CH4 and N2O emissions are estimated for 2006 and 2007 using four inverse modelling systems, based on different global and regional Eulerian and Lagrangian transport models. This ensemble approach is designed to provide more realistic estimates of the overall uncertainties in the derived

  5. Continuous flow IRMS application to CH4, MNHCS, and N2O in the atmosphere and the oceans

    International Nuclear Information System (INIS)

    Yoshida, N.; Tsunogai, U.; Toyoda, S.

    2001-01-01

    The application of CF-IRMS to measurement of methane (CH4), non-methane hydrocarbons (NMHCS), and nitrous oxide (N 2 O) is outlined and preliminary information on isotopic variations in the atmosphere and oceans is presented. Labelling of these compounds is expected to provide a robust method for tracing sources, sinks and controlling processes in the environment. (author)

  6. Effects of rice straw mulching on N2O emissions and maize productivity in a rain-fed upland.

    Science.gov (United States)

    Wu, Xiao Hong; Wang, Wei; Xie, Xiao Li; Yin, Chun Mei; Hou, Hai Jun

    2018-03-01

    In the hilly areas of southern China, uplands and paddies are located adjacent to each other. Using rice straw as mulch for upland soil may improve crop production and partially replace chemical fertilizers, which may mitigate N 2 O emissions. A field experiment was conducted to investigate the potential of rice straw mulching for mitigating N 2 O emissions and increasing crop production. The treatments included no mulching (CK), 5000 kg ha -1 of straw mulching (SM5), and 10,000 kg ha -1 of straw mulching (SM10). Moreover, all the treatments received equivalent amounts of nitrogen, phosphorus, and potassium from chemical fertilizers plus rice straw. Relative to CK, cumulative N 2 O emissions decreased by 23.1 and 33.5% with SM5 and SM10, respectively. Significant positive correlations were observed between N 2 O fluxes and soil water-filled pore space (WPFS) (r 2  = 0.495, P mulching, while achieving improved crop yield. This management strategy has great potential, and this study provides an important reference for low-carbon agriculture.

  7. N loss to drain flow and N2O emissions from a corn-soybean rotation with winter rye

    Science.gov (United States)

    Anthropogenic perturbation of the global nitrogen cycle and its effects on the environment such as hypoxia in coastal regions and increased N2O emissions is of increasing, cross-disciplinary, worldwide concern, and agricultural production is a major contributor. Only limited studies, however, have s...

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

    Science.gov (United States)

    2014-07-01

    ammonium perchlorate (AP) which has been widely used in solid rocket motors for the past 50 years. Ammonium perchlorate is stable at room temperature...Q. Z. Qin, Photoisomerization of N2O3 in an Ar matrix, J. Photochem. Photobio. A 1999, 122, 1-5. [15] a) A. Stirling , I. Papai, J. Mink, D. R

  9. Suitability of quantum cascade laser spectroscopy for CH4 and N2O eddy covariance flux measurements

    Directory of Open Access Journals (Sweden)

    A. T. Vermeulen

    2007-08-01

    Full Text Available A quantum cascade laser spectrometer was evaluated for eddy covariance flux measurements of CH4 and N2O using three months of continuous measurements at a field site. The required criteria for eddy covariance flux measurements including continuity, sampling frequency, precision and stationarity were examined. The system operated continuously at a dairy farm on peat grassland in the Netherlands from 17 August to 6 November 2006. An automatic liquid nitrogen filling system for the infrared detector was employed to provide unattended operation of the system. The electronic sampling frequency was 10 Hz, however, the flow response time was 0.08 s, which corresponds to a bandwidth of 2 Hz. A precision of 2.9 and 0.5 ppb Hz−1/2 was obtained for CH4 and N2O, respectively. Accuracy was assured by frequent calibrations using low and high standard additions. Drifts in the system were compensated by using a 120 s running mean filter. The average CH4 and N2O exchange was 512 ngC m−2 s−1 (2.46 mg m−2 hr−1 and 52 ngN m−2 s−1 (0.29 mg m−2 hr−1. Given that 40% of the total N2O emission was due to a fertilizing event.

  10. Catalytic Activity of Cobalt Grafted on Ordered Mesoporous Silica Materials in N2O Decomposition and CO Oxidation.

    Czech Academy of Sciences Publication Activity Database

    Kuboňová, L.; Peikertová, P.; Mamulová Kutláková, K.; Jirátová, Květa; Słowik, G.; Obalová, L.; Cool, P.

    2017-01-01

    Roč. 437, AUG 2017 (2017), s. 57-72 ISSN 2468-8231 R&D Projects: GA ČR GA14-13750S Institutional support: RVO:67985858 Keywords : mesoporous ordered silica * cobalt * N2O decomposition Subject RIV: CI - Industrial Chemistry, Chemical Engineering OBOR OECD: Chemical process engineering

  11. Is biochar-manure co-compost a better solution for soil health improvement and N2O emissions mitigation?

    Science.gov (United States)

    Land application of compost has been a promising remediation strategy for soil health and environmental quality, but substantial emissions of greenhouse gases, especially N2O, need to be controlled during making and using compost. Biochar as a bulking agent for composting has bee...

  12. Effect of Preparation Method on Catalytic Properties of Co-Mn-Al Mixed Oxides for N2O Decomposition.

    Czech Academy of Sciences Publication Activity Database

    Klyushina, A.; Pacultová, K.; Karásková, K.; Jirátová, Květa; Ritz, M.; Fridrichová, D.; Volodorskaja, A.; Obalová, L.

    2016-01-01

    Roč. 425, DEC 15 (2016), s. 237-247 ISSN 1381-1169 R&D Projects: GA ČR GA14-13750S Institutional support: RVO:67985858 Keywords : Co-Mn-Al mixed oxide * N2O decomposition * preparation methods Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 4.211, year: 2016

  13. The Effects of Land-Use Change from Grassland to Miscanthus x giganteus on Soil N2O Emissions

    Directory of Open Access Journals (Sweden)

    Michael Williams

    2013-09-01

    Full Text Available A one year field trial was carried out on three adjacent unfertilised plots; an 18 year old grassland, a 14 year old established Miscanthus crop, and a 7 month old newly planted Miscanthus crop. Measurements of N2O, soil temperature, water filled pore space (WFPS, and inorganic nitrogen concentrations, were made every one to two weeks. Soil temperature, WFPS and NO3− and NH4+ concentrations were all found to be significantly affected by land use. Temporal crop effects were also observed in soil inorganic nitrogen dynamics, due in part to C4 litter incorporation into the soil under Miscanthus. Nonetheless, soil N2O fluxes were not significantly affected by land use. Cumulative yearly N2O fluxes were relatively low, 216 ± 163, 613 ± 294, and 377 ± 132 g·N·ha−1·yr−1 from the grassland, newly planted Miscanthus, and established Miscanthus plots respectively, and fell within the range commonly observed for unfertilised grasslands dominated by perennial ryegrass (Lolium perenne. Higher mean cumulative fluxes were measured in the newly planted Miscanthus, which may be linked to a possible unobserved increase immediately after establishment. However, these differences were not statistically significant. Based on the results of this experiment, land-use change from grassland to Miscanthus will have a neutral impact on medium to long-term N2O emissions.

  14. Simulating N2O emissions from global forests and grasslands using process-based TRIPLEX-GHG model

    Science.gov (United States)

    Peng, C.; Zhu, Q.; Zhang, K.

    2017-12-01

    This study has described the successful integration of nitrification and denitrification submodules by incorporating N2O production, consumption, and diffusion processes into a DGVM model. Results from our sensitivity analysis indicated that the nitrification rate coefficient (COENR) is the main N2O emission modeling parameter. TRIPLEX-GHG was calibrated according to data obtained from 29 sites across different forests and grasslands around the world, which represents a more extensive sampling size compared to previous models. The average COENR value gradually increased from tropical forest to grassland to temperate forest to boreal forest, with means of 0.009, 0.03, 0.04, and 0.09, respectively. Validation was further confirmed using mean COENR values from 52 global sites from different biomes around the world. Although our model proved less robust in modeling N2O uptake and peaks during periods of snowmelt, the seasonal variations and magnitudes of simulations were good overall, and annual observed and simulated data were highly correlated (R2=0.75), which indicated that TRIPLEX-GHG can be applied to N2O emission modeling across different ecosystems and latitudes. Lastly, TRIPLEX-GHG is intended to contribute to the scientific modeling community by accounting for greenhouse gas exchanges and budgets at both regional and global scales.

  15. Catalytic decomposition of N2O over CeO2 supported Co3O4 catalysts

    Indian Academy of Sciences (India)

    128, No. 11, November 2016, pp. 1795–1804. c Indian Academy of Sciences. DOI 10.1007/s12039-016-1180-3. Catalytic decomposition of N2O over CeO2 supported Co3O4 catalysts. S K MAHAMMADUNNISA, T AKANKSHA, K KRUSHNAMURTY and. CH SUBRAHMANYAM. ∗. Energy and Environmental Research Lab, ...

  16. Summer fluxes of atmospheric greenhouse gases N2O, CH4 and CO2 from mangrove soil in South China.

    Science.gov (United States)

    Chen, G C; Tam, N F Y; Ye, Y

    2010-06-01

    The atmospheric fluxes of N(2)O, CH(4) and CO(2) from the soil in four mangrove swamps in Shenzhen and Hong Kong, South China were investigated in the summer of 2008. The fluxes ranged from 0.14 to 23.83 micromol m(-2)h(-1), 11.9 to 5168.6 micromol m(-2)h(-1) and 0.69 to 20.56 mmol m(-2)h(-1) for N(2)O, CH(4) and CO(2), respectively. Futian mangrove swamp in Shenzhen had the highest greenhouse gas fluxes, followed by Mai Po mangrove in Hong Kong. Sha Kong Tsuen and Yung Shue O mangroves in Hong Kong had similar, low fluxes. The differences in both N(2)O and CH(4) fluxes among different tidal positions, the landward, seaward and bare mudflat, in each swamp were insignificant. The N(2)O and CO(2) fluxes were positively correlated with the soil organic carbon, total nitrogen, total phosphate, total iron and NH(4)(+)-N contents, as well as the soil porosity. However, only soil NH(4)(+)-N concentration had significant effects on CH(4) fluxes. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  17. Structure reactivity relationships during N2O hydrogenation over Au-Ag alloys: A study by field emission techniques

    Science.gov (United States)

    Jacobs, Luc; Barroo, Cédric; Gilis, Natalia; Lambeets, Sten V.; Genty, Eric; Visart de Bocarmé, Thierry

    2018-03-01

    To make available atomic oxygen at the surface of a catalyst is the key step for oxidation reactions on Au-based catalysts. In this context, Au-Ag alloys catalysts exhibit promising properties for selective oxidation reactions of alcohols: low temperature activity and high selectivity. The presence of O(ads) and its effects on the catalytic reactivity is studied via the N2O dissociative adsorption and subsequent hydrogenation. Field emission techniques are particularly suited to study this reaction: Field Ion Microscopy (FIM) and Field Emission Microscopy (FEM) enable to image the extremity of sharp metallic tips, the size and morphology of which are close to those of one single catalytic particle. The reaction dynamics is studied in the 300-320 K temperature range and at a pressure of 3.5 × 10-3 Pa. The main results are a strong structure/reactivity relationship during N2O + H2 reaction over Au-8.8 at.%Ag model catalysts. Comparison of high-resolution FIM images of the clean sample and FEM images during reaction shows a sensitivity of the reaction to the local structure of the facets, independently of the used partial pressures of both N2O and H2. This suggests a localised dissociative adsorption step for N2O and H2 with the formation of a reactive interface around the {210} facets.

  18. Effects of N2O plasma treatment on perhydropolysilazane spin-on-dielectrics for inter-layer-dielectric applications

    International Nuclear Information System (INIS)

    Park, Kyoung-Seok; Ko, Pil-Seok; Kim, Sam-Dong

    2014-01-01

    Effects of the N 2 O plasma treatment (PT) on perhydropolysilazane spin-on-dielectric (PHPS SOD) were examined as potential inter-layer-dielectrics (ILDs) for sub-30 nm Si circuits. The spin-coated PHPS (18.5 wt.%) ILD layers converted at 650 °C were integrated with the 0.18 μm Si front-end-of-the line process. A modified contact pre-cleaning scheme using N 2 O PT produced more uniform and stable contact chain resistances from the SOD ILDs than the case of pre-cleaning only by buffered oxide etcher. Our analysis shows that this enhancement is due to the minimized carbon contamination on the PHPS side-wall surface densified by PT. - Highlights: • Perhydropolysilazane (PHPS) layer is evaluated as a Si interlayer dielectric. • Examine effects of the N 2 O plasma treatment (PT) on PHPS spin-on-dielectrics (SODs) • Significantly improved metal contact resistances are achieved using the N 2 O PT. • Contact resistance enhancement by PT is due to the minimized carbon contamination

  19. Contribution of N2O to the greenhouse gas balance of first-generation biofuels : climate change and biofuels

    NARCIS (Netherlands)

    Smeets, E.M.W.; Bouwman, A.F.; Stehfest, E.; van Vuuren, D.P.; Posthuma, A.

    2009-01-01

    In this study, we analyze the impact of fertilizer- and manure-induced N2O emissions due to energy crop production on the reduction of greenhouse gas (GHG) emissions when conventional transportation fuels are replaced by first-generation biofuels (also taking account of other GHG emissions during

  20. Using Extractive FTIR to Measure N2O from Medium Heavy Duty Vehicles Powered with Diesel and Biodiesel Fuels

    Science.gov (United States)

    A Fourier Transform Infrared (FTIR) spectrometer was used to measure N2O and other pollutant gases during an evaluation of two medium heavy-duty diesel trucks equipped with a Diesel Particulate Filter (DPF). The emissions of these trucks were characterized under a variety of oper...

  1. Biogenic CH4 and N2O emissions overwhelm land CO2 sink in Asia: Toward a full GHG budget

    Science.gov (United States)

    Tian, H.

    2017-12-01

    The recent global assessment indicates the terrestrial biosphere as a net source of greenhouse gases to the atmosphere (Tian et al Nature 2016). The fluxes of greenhouse gases (GHG) vary by region. Both TD and BU approaches indicate that human-caused biogenic fluxes of CO2, CH4 and N2O in the biosphere of Southern Asia led to a large net climate warming effect, because the 100-year cumulative effects of CH4 and N2O emissions together exceed that of the terrestrial CO2 sink. Southern Asia has about 90% of the global rice fields and represents more than 60% of the world's nitrogen fertilizer consumption, with 64%-81% of CH4 emissions and 36%-52% of N2O emissions derived from the agriculture and waste sectors. Given the large footprint of agriculture in Southern Asia, improved fertilizer use efficiency, rice management and animal diets could substantially reduce global agricultural N2O and CH4 emissions. This study highlights the importance of including all three major GHGs in regional climate impact assessments, mitigation option and climate policy development.

  2. Earthworm-induced N mineralization in fertilized grassland increases both N2O emission and crop-N uptake

    NARCIS (Netherlands)

    Lubbers, I.M.; Brussaard, L.; Otten, W.; Groenigen, van J.W.

    2011-01-01

    Earthworms can increase plant nitrogen (N) availability by stimulating mineralization of organic matter. However, recent studies show that they can also cause elevated emission of the greenhouse gas nitrous oxide (N2O). It is unclear to what extent these two effects occur in fertilized grasslands,

  3. Shallow tillage generates higher N2O emissions: results of continuous chamber-based measurement in a winter wheat field.

    Science.gov (United States)

    Broux, François; Lognoul, Margaux; Theodorakopoulos, Nicolas; Hiel, Marie-Pierre; Bodson, Bernard; Heinesch, Bernard; Aubinet, Marc

    2017-04-01

    Agriculture is one of the most important contributors to GHG emission, notably through fertilized croplands. Though, few publications have studied simultaneously and through continuous measurement the N2O and CO2 emissions in cultivated lands. We conducted this study to assess the effect of farming practices and climate on both N2O and CO2 emissions from a winter wheat crop. The experiment was held in an experimental field in the loamy region in Belgium from March 2016 till crop harvest in August 2016. The fluxes were measured on two nearby parcels in a winter wheat field with restitution of the residues from previous crop. For the past 8 years, one parcel was subjected to a shallow tillage (ST, 10 cm depth) and the other one to a conventional tillage (CT, 25 cm depth). On each parcel, the emissions are assessed with homemade automated closed chambers. Measurement continuity and good temporal resolution (one mean flux every 4 hours) of the system allowed a fine detection and quantification of the emission peaks which usually represent the major part of N2O fluxes. In addition to gas fluxes, soil water content and temperature were measured continuously. Soil samples were taken regularly to determine soil pH, soil organic carbon and nitrogen pools (total, NO3- and NH4+) and study microbial diversity and nitrification/denitrification gene expression. Unexpectedly, results showed N2O emissions twice as large in the ST parcel as in the CT parcel. On the contrary, less important CO2 emissions were observed under ST. Several emission peaks of N2O were observed during the measurement period. The peaks occurred after fertilization events and seemed to be triggered by an elevation of soil water content. Interesting links could be made between soil NH4-N and NO3-N pools and N2O emissions. Nitrification being the main process originating the fluxes was suggested on the one hand by the temporal evolution of nitrogen pools and N2O emissions and on the other hand by the relation

  4. Temporal and spatial variations of soil CO2, CH4 and N2O fluxes at three differently managed grasslands

    Directory of Open Access Journals (Sweden)

    D. Imer

    2013-09-01

    Full Text Available A profound understanding of temporal and spatial variabilities of soil carbon dioxide (CO2, methane (CH4 and nitrous oxide (N2O fluxes between terrestrial ecosystems and the atmosphere is needed to reliably quantify these fluxes and to develop future mitigation strategies. For managed grassland ecosystems, temporal and spatial variabilities of these three soil greenhouse gas (GHG fluxes occur due to changes in environmental drivers as well as fertilizer applications, harvests and grazing. To assess how such changes affect soil GHG fluxes at Swiss grassland sites, we studied three sites along an altitudinal gradient that corresponds to a management gradient: from 400 m a.s.l. (intensively managed to 1000 m a.s.l. (moderately intensive managed to 2000 m a.s.l. (extensively managed. The alpine grassland was included to study both effects of extensive management on CH4 and N2O fluxes and the different climate regime occurring at this altitude. Temporal and spatial variabilities of soil GHG fluxes and environmental drivers on various timescales were determined along transects of 16 static soil chambers at each site. All three grasslands were N2O sources, with mean annual soil fluxes ranging from 0.15 to 1.28 nmol m−2 s−1. Contrastingly, all sites were weak CH4 sinks, with soil uptake rates ranging from −0.56 to −0.15 nmol m−2 s−1. Mean annual soil and plant respiration losses of CO2, measured with opaque chambers, ranged from 5.2 to 6.5 μmol m−2 s−1. While the environmental drivers and their respective explanatory power for soil N2O emissions differed considerably among the three grasslands (adjusted r2 ranging from 0.19 to 0.42, CH4 and CO2 soil fluxes were much better constrained (adjusted r2 ranging from 0.46 to 0.80 by soil water content and air temperature, respectively. Throughout the year, spatial heterogeneity was particularly high for soil N2O and CH4 fluxes. We found permanent hot spots for soil N2O emissions as well as

  5. N2O and N2 emissions from contrasting soil environments - interactive effects of soil nitrogen, hydrology and microbial communities

    Science.gov (United States)

    Christiansen, Jesper; Elberling, Bo; Ribbons, Relena; Hedo, Javier; José Fernández Alonso, Maria; Krych, Lukasz; Sandris Nielsen, Dennis; Kitzler, Barbara

    2016-04-01

    Reactive nitrogen (N) in the environment has doubled relative to the natural global N cycle with consequences for biogeochemical cycling of soil N. Also, climate change is expected to alter precipitation patterns and increase soil temperatures which in Arctic environments may accelerate permafrost thawing. The combination of changes in the soil N cycle and hydrological regimes may alter microbial transformations of soil N with unknown impacts on N2O and N2 emissions from temperate and Arctic soils. We present the first results of soil N2O and N2 emissions, chemistry and microbial communities over soil hydrological gradients (upslope, intermediate and wet) across a global N deposition gradient. The global gradient covered an N-limited high Arctic tundra (Zackenberg-ZA), a pacific temperate rain forest (Vancouver Island-VI) and an N saturated forest in Austria (Klausenleopoldsdorf-KL). The N2O and N2 emissions were measured from intact cores at field moisture in a He-atmosphere system. Extractable NH4+ and NO3-, organic and microbial C and N and potential enzyme-activities were determined on soil samples. Soil genomic DNA was subjected to MiSeq-based tag-encoded 16S rRNA and ITS gene amplicon sequencing for the bacterial and fungal community structure. Similar soil moisture levels were observed for the upslope, intermediate and wet locations at ZA, VI and KL, respectively. Extractable NO3- was highest at the N rich KL and lowest at ZA and showed no trend with soil moisture similar to NH4+. At ZA and VI soil NH4+ was higher than NO3- indicating a tighter N cycling. N2O emissions increased with soil moisture at all sites. The N2O emissions for the wet locations ranked similarly to NO3- with the largest response to soil moisture at KL. N2 emissions were remarkably similar across the sites and increased with soil wetness. Microbial C and N also increased with soil moisture and were overall lowest at the N rich KL site. The potential activity of protease enzyme was site

  6. A Tale of Two Gases: Isotope Effects Associated with the Enzymatic Production of H2 and N2O

    Science.gov (United States)

    Yang, H.; Gandhi, H.; Kreuzer, H. W.; Moran, J.; Hill, E. A.; McQuarters, A.; Lehnert, N.; Ostrom, N. E.; Hegg, E. L.

    2014-12-01

    Stable isotopes can provide considerable insight into enzymatic mechanisms and fluxes in various biological processes. In our studies, we used stable isotopes to characterize both enzyme-catalyzed H2 and N2O production. H2 is a potential alternative clean energy source and also a key metabolite in many microbial communities. Biological H2 production is generally catalyzed by hydrogenases, enzymes that combine protons and electrons to produce H2 under anaerobic conditions. In our study, H isotopes and fractionation factors (α) were used to characterize two types of hydrogenases: [FeFe]- and [NiFe]-hydrogenases. Due to differences in the active site, the α associated with H2 production for [FeFe]- and [NiFe]-hydrogenases separated into two distinct clusters (αFeFe > αNiFe). The calculated kinetic isotope effects indicate that hydrogenase-catalyzed H2 production has a preference for light isotopes, consistent with the relative bond strengths of O-H and H-H bonds. Interestingly, the isotope effects associated with H2 consumption and H2-H2O exchange reactions were also characterized, but in this case no specific difference was observed between the different enzymes. N2O is a potent greenhouse gas with a global warming potential 300 times that of CO2, and the concentration of N2O is currently increasing at a rate of ~0.25% per year. Thus far, bacterial and fungal denitrification processes have been identified as two of the major sources of biologically generated N2O. In this study, we measured the δ15N, δ18O, δ15Nα (central N atom in N2O), and δ15Nβ (terminal N atom in N2O) of N2O generated by purified fungal P450 nitric oxide reductase (P450nor) from Histoplasma capsulatum. We observed normal isotope effects for δ18O and δ15Nα, and inverse isotope effects for bulk δ15N (the average of Nα and Nβ) and δ15Nβ. The observed isotope effects have been used in conjunction with DFT calculations to provide important insight into the mechanism of P450nor. Similar

  7. Emissions of N2O from organic soils managed by agriculture in North Western Denmark (Possible production and reduction spots)

    Science.gov (United States)

    Taghizadeh-Toosi, Arezoo; Elsgaard, Lars; Ernstsen, Vibeke; Clough, Tim J.; Petersen, Søren O.

    2017-04-01

    In North Western Denmark, organic soils are extensively under agricultural management for cereal and high-value cash crop production or as grazing land. The area (overlying raised seabed) has been classified as potentially acid sulfate soil. Drainage and tillage of organic soil is known to promote emissions of nitrous oxide (N2O), but a previous monitoring program found annual N2O emissions from adjacent fields with rotational grass and potato that were, respectively, 3 and 5 times higher than default values proposed by The Intergovernmental Panel on Climate Change (IPCC, 2014). In order to study underlying mechanisms, the same two sites and two new reference sites along an East-West transect were investigated during 2015. The four sites (i.e. two with rotational grass and two sites with a potato crop) were equipped for weekly monitoring of soil surface N2O emissions and sub-soil N2O concentrations to 1 m depth during spring and autumn 2015. Also, various environmental variables (precipitation, air and soil temperature, soil moisture, groundwater level, and soil mineral N) were monitored. In April and August 2015, intact cores to 1 m depth were collected at the paired grassland and potato sites and analysed for pH, EC, nitrite, reactive Fe, acid volatile S (AVS) and chromium-reducible S (CRS). Nitrous oxide concentrations in the soil profile showed strong temporal dynamics reflecting water table changes, as well as precipitation and in some cases fertilization. At the paired site concentrations in the potato field (reaching 2000 μL N2O L-1) were much higher than in the adjacent grassland (up to 20 μL N2O L-1). Soil pH averaged 4.9 at the two paired sites. The difference was confirmed at reference sites. Accumulated emissions of N2O during monitoring periods (in total 151-174 d) corresponded to 18 and 48 kg N ha-1 at potato sites, but only 3 and 4 kg N ha-1 at the grassland sites. Nitrous oxide accumulated at depth in the soil during phases of declining water

  8. Effects of agricultural practices on greenhouse gas emissions (N2O, CH4 and CO2) from corn fields

    Science.gov (United States)

    Hui, D.; Wang, J.; Jima, T.; Dennis, S.; Stockert, C.; Smart, D.; Bhattarai, S.; Brown, K.; Sammis, T.; Reddy, C.

    2012-12-01

    The United States is, by far, the largest producer of corn (Zea mays L.) in the world. Recent increases in fertilizer cost and concerns over global climate change have farmers and others interested in more efficient fertilization management and greenhouse gas emissions reductions. To seek the best management practices, we conducted field experiments during the 2012 growing season at Tennessee State University Agricultural Research and Demonstration Center in Nashville, TN. Six treatments were applied including regular URAN application [2 times], multiple URAN applications [4 times], denitrification inhibitor with regular URAN application, and chicken litter plus regular URAN application in no-tilled plots, and URAN application plus bio-char in tilled plots, all compared to regular URAN application in conventional tilled plots. Each treatment was replicated six times (blocks). We measured N2O, CO2 and CH4 emissions using a closed chamber method after rainfall events, fertilizer applications or every two weeks whichever was shorter. Corresponding soil NH4+-N and NO3--N, soil temperature and moisture were also measured during the gas sampling. Plant physiology and growth were measured about every two weeks. While preliminary results indicate that N2O and CO2 fluxes were significantly influenced by the agricultural practices on some days, particularly after rainfall events, CH4 flux was not influenced by the treatments during most of the days. Plots with bio-char showed significantly lower N2O emissions. We also measured N2O flux in a commercial corn field using the Eddy Covariance (EC) technique to ground verify the chamber based N2O emissions at the field scale. Results obtained with the EC technique seem comparable with the chamber method.

  9. Emissions of N2O and CH4 from agricultural soils amended with two types of biogas residues

    International Nuclear Information System (INIS)

    Odlare, M.; Abubaker, J.; Lindmark, J.; Pell, M.; Thorin, E.; Nehrenheim, E.

    2012-01-01

    Biogas residues contain valuable plant nutrients, important to the crops and also to soil microorganisms. However, application of these materials to the soils may contribute to the emission of greenhouse gases (GHG) causing global warming and climate change. In the present study, incubation experiment was carried out, where the emission rates of N 2 O and CH 4 were measured after amending two soils with two types of biogas residues: (1) a regular residue from a large scale biogas plant (BR) and (2) a residue from an ultra-filtration membrane unit connected to a pilot-scale biogas plant (BRMF). The emissions of N 2 O and CH 4 were measured at two occasions: at 24 h and at 7 days after residue amendment, respectively. Amendment with filtered biogas residues (BRMF) led to an increase in N 2 O emissions with about 6–23 times in organic and clay soil, respectively, in comparison to unfiltered biogas residues (BR). Methane emission was detected in small amounts when filtered biogas residue was added to the soil. Amendment of unfiltered biogas to the organic soil resulted in net consumption. In conclusion, fertilization with BRMF can be combined with risk of an increase N 2 O emission, especially when applied to organic soils. However, in order to transfer these results to real life agriculture, large scale field studies need to be carried out. -- Highlights: ► Membrane filtration of biogas process water is a promising method. ► Fertilization of biogas residue may increase the N 2 O emission from soil. ► Organic soils produced higher emissions than clay soils.

  10. Effect of dolomite and biochar addition on N2O and CO2 emissions from acidic tea field soil.

    Science.gov (United States)

    Oo, Aung Zaw; Sudo, Shigeto; Akiyama, Hiroko; Win, Khin Thuzar; Shibata, Akira; Yamamoto, Akinori; Sano, Tomohito; Hirono, Yuhei

    2018-01-01

    A laboratory study was conducted to study the effects of liming and different biochar amendments on N2O and CO2 emissions from acidic tea field soil. The first experiment was done with three different rates of N treatment; N 300 (300 kg N ha-1), N 600 (600 kg N ha-1) and N 900 (900 kg N ha-1) and four different rates of bamboo biochar amendment; 0%, 0.5%, 1% and 2% biochar. The second experiment was done with three different biochars at a rate of 2% (rice husk, sawdust, and bamboo) and a control and lime treatment (dolomite) and control at two moisture levels (50% and 90% water filled pore space (WFPS)). The results showed that dolomite and biochar amendment significantly increased soil pH. However, only biochar amendment showed a significant increase in total carbon (C), C/N (the ratio of total carbon and total nitrogen), and C/IN ratio (the ratio of total carbon and inorganic nitrogen) at the end of incubation. Reduction in soil NO3--N concentration was observed under different biochar amendments. Bamboo biochar with the rates of 0.5, 1 and 2% reduced cumulative N2O emission by 38%, 48% and 61%, respectively, compare to the control soil in experiment 1. Dolomite and biochar, either alone or combined significantly reduced cumulative N2O emission by 4.6% to 32.7% in experiment 2. Reduction in N2O production under biochar amendment was due to increases in soil pH and decreases in the magnitude of mineral-N in soil. Although, both dolomite and biochar increased cumulative CO2 emission, only biochar amendment had a significant effect. The present study suggests that application of dolomite and biochar to acidic tea field soil can mitigate N2O emissions.

  11. Occurrence of greenhouse gases (CO2, N2O and CH4) in groundwater of the Walloon Region (Belgium).

    Science.gov (United States)

    Jurado, Anna; Borges, Alberto V.; Pujades, Estanislao; Hakoun, Vivien; Knöller, Kay; Brouyère, Serge

    2017-04-01

    Greenhouse gases (GHGs) are an environmental problem because their concentrations in the atmosphere have continuously risen since the industrial revolution. They can be indirectly transferred to the atmosphere through groundwater discharge into surface water bodies such as rivers. However, their occurrence is poorly evaluated in groundwater. The aim of this work is to identify the hydrogeological contexts (e.g., chalk and limestone aquifers) and the most conductive conditions for the generation of GHGs in groundwater at a regional scale. To this end, carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) concentrations, major and minor elements and environmental isotopes were monitored in several groundwater bodies of the Walloon Region (Belgium) from September 2014 to June 2016. The concentrations of GHGs in groundwater ranged from 1769 to 100519 ppm for the partial pressure of CO2 and from 0 to 1064 nmol/L and 1 to 37062 nmol/L for CH4 and N2O respectively. Overall, groundwater was supersaturated in GHGs with respect to atmospheric equilibrium, suggesting that groundwater contribute to the atmospheric GHGs budget. Prior inspection of the data suggested that N2O in groundwater can be produced by denitrification and nitrification. The most suitable conditions for the accumulation of N2O are promoted by intermediate dissolved oxygen concentrations (2.5-3 mg L-1) and the availability of nitrate (NO3-). These observations will be compared with the isotopes of NO3-. CH4 was less detected and at lower concentration than N2O, suggesting that groundwater redox conditions are not reducing enough to promoted the production of CH4. The results will be presented and discussed in detail in the presentation.

  12. Nitritation and N2O Emission in a Denitrification and Nitrification Two-Sludge System Treating High Ammonium Containing Wastewater

    Directory of Open Access Journals (Sweden)

    Guangxue Wu

    2014-10-01

    Full Text Available The effective management of high ammonium containing wastewater is important for the sustainable development of the wastewater industry. A pre-denitrification and post-nitrification two-sludge system was proposed to treat high ammonium containing wastewater with low carbon-to-nitrogen (C/N ratios. In the system, pre-denitrification was adopted to use organic carbon in raw wastewater efficiently for nitrogen removal, while post-nitrification was adopted to achieve nitritation. System performance and the characteristics of nitrous oxide (N2O emission were examined. As to the influent chemical oxygen demand (COD and ammonium nitrogen (NH4-N concentration, both 800 mg/L, nitrogen removal was mainly through pre-denitrification, and the nitrogen removal percentage was 43.4%. In post-nitrification, nitritation was achieved with a nitrite accumulation efficiency of 97.8% and a NH4-N removal loading rate of 0.45 g/(L·d. With nitrite as the electron acceptor during denitrification, its removal rate increased, while the N2O emission factor decreased with increasing C/N ratios. Nitrification was affected significantly by the aeration rate. When the aeration rate was below 0.6 L/min, the NH4-N removal rate increased, while the N2O emission rate decreased with increasing aeration rates. However, when the aeration rate was above 0.6 L/min, it had little influence on N2O emission. During nitrification, N2O emission factors decreased exponentially with increasing ammonium oxidation rates.

  13. Soil water content drives spatiotemporal patterns of CO2 and N2O emissions from a Mediterranean riparian forest soil

    Science.gov (United States)

    Poblador, Sílvia; Lupon, Anna; Sabaté, Santiago; Sabater, Francesc

    2017-09-01

    Riparian zones play a fundamental role in regulating the amount of carbon (C) and nitrogen (N) that is exported from catchments. However, C and N removal via soil gaseous pathways can influence local budgets of greenhouse gas (GHG) emissions and contribute to climate change. Over a year, we quantified soil effluxes of carbon dioxide (CO2) and nitrous oxide (N2O) from a Mediterranean riparian forest in order to understand the role of these ecosystems on catchment GHG emissions. In addition, we evaluated the main soil microbial processes that produce GHG (mineralization, nitrification, and denitrification) and how changes in soil properties can modify the GHG production over time and space. Riparian soils emitted larger amounts of CO2 (1.2-10 g C m-2 d-1) than N2O (0.001-0.2 mg N m-2 d-1) to the atmosphere attributed to high respiration and low denitrification rates. Both CO2 and N2O emissions showed a marked (but antagonistic) spatial gradient as a result of variations in soil water content across the riparian zone. Deep groundwater tables fueled large soil CO2 effluxes near the hillslope, while N2O emissions were higher in the wet zones adjacent to the stream channel. However, both CO2 and N2O emissions peaked after spring rewetting events, when optimal conditions of soil water content, temperature, and N availability favor microbial respiration, nitrification, and denitrification. Overall, our results highlight the role of water availability on riparian soil biogeochemistry and GHG emissions and suggest that climate change alterations in hydrologic regimes can affect the microbial processes that produce GHG as well as the contribution of these systems to regional and global biogeochemical cycles.

  14. The Effect of Biofertilizer on The Diversity of N2O Reducing Bacteria in Paddy Fields of Sukabumi, Indonesia

    Directory of Open Access Journals (Sweden)

    Alfan Cahyadi

    2017-12-01

    Full Text Available Some of the methanotrophic bacteria and N2O reducing bacteria have been proven to be able to support the plant growth and increase the productivity of paddy. However effect of the methanotrophic and N2O reducing bacteria application as a biofertilizer to indigenous N2O reducing bacteria is still not well known yet. The aim of this study was to analyze the diversity of N2O reducing bacteria in lowland paddy soil based on a nosZ gene. Soil samples were taken from lowland paddy soils in Pelabuhan Ratu Sukabumi, West Java, Indonesia. There were two treatments for the paddy field soil, ie. biofertilizer-treated field 20% fertilizer (50 kg/ha with the addition of biofertilizer and 100% fertilizer. PCR amplification of nosZ gene was successfully conducted using nosZF and nosZR primer pair. Denaturing Gradient Gel Electrophoresis (DGGE process was conducted at 150 V for 5.5h. There were three differences nosZ bands were sequenced. The phylogenetic analysis showed that they were close to uncultured bacteria. Microbial diversity in the biofertilizer-treated field was higher than that of in the 100% fertilizer-treated field. The biofertilizer treatment has higher in microbial diversity than that of applied non-biofertilizer paddy fields. This research might have impact in the application of biofertilizers due to the emission of N2O as a green house gas from paddy fields farming activity. The biofertilizer has great potential application in sustainable environmental friendly agriculture systems.

  15. The pH dependency of N-converting enzymatic processes, pathways and microbes: effect on net N2O production

    DEFF Research Database (Denmark)

    Blum, Jan-Michael; Su, Qingxian; Ma, Yunjie

    2018-01-01

    how pH affects enzymes, pathways and microorganisms that are involved in N-conversions in water engineering applications. At a molecular level, pH affects activity of cofactors and structural elements of relevant enzymes by protonation or deprotonation of amino acid residues or solvent ligands, thus...... causing steric changes in catalytic sites or proton/electron transfer routes that alter the enzymes' overall activity. Augmenting molecular information with, e.g., nitritation or denitrification rates yields explanations of changes in net N2 O production with pH. Ammonia oxidizing bacteria are of highest......Nitrous oxide (N2 O) is emitted during microbiological nitrogen (N) conversion processes, when N2 O production exceeds N2 O consumption. The magnitude of N2 O production vs. consumption varies with pH and controlling net N2 O production might be feasible by choice of system pH. This article reviews...

  16. Counter-diffusion biofilms have lower N2O emissions than co-diffusion biofilms during simultaneous nitrification and denitrification: Insights from depth-profile analysis

    DEFF Research Database (Denmark)

    Kinh, Co Thi; Suenaga, Toshikazu; Hori, Tomoyuki

    2017-01-01

    geometries, i.e., a MABR and a conventional biofilm reactor (CBR) employing co-current substrate diffusion geometry, were operated to determine depth profiles of dissolved oxygen (DO), nitrous oxide (N2O), functional gene abundance and microbial community structure. Surficial nitrogen removal rate...... (0.011 ± 0.001 mg N2O-N/L) than that in the CBR (1.38 ± 0.25 mg N2O-N/L), resulting in distinct N2O emission factors (0.0058 ± 0.0005% in the MABR vs. 0.72 ± 0.13% in the CBR). Analysis on local net N2O production and consumption rates unveiled that zones for N2O production and consumption were...

  17. Influence of 13 different biochars on N2O production and its sources during rewetting-drying cycles

    Science.gov (United States)

    Wrage-Mönnig, Nicole; Fiedler, Sebastian; Fuertes-Mendizábal, Teresa; Estavillo, José-Maria; Ippolito, Jim A.; Borchard, Nils; Cayuela, Maria Luz; Spokas, Kurt; Novak, Jeff; Kammann, Claudia

    2017-04-01

    Biochars have been found to have variable impacts on nitrous oxide (N2O) emissions. The variability has been attributed to differences in soil - biochar properties and microbial communities. While some information exists on biochar and soil properties, the effect of biochars on microbial sources of N2O is still a matter of speculation. In this study, we tested these effects for12 biochars prepared from cypress, loblolly pine and grape wood produced at four different controlled temperatures (350, 500, 700 and 900˚ C), respectively, plus a grapevine Kontiki biochar (600-700˚ C). The biochars were added (2%) to a loamy sand brought to pH 7.1 with CaO. The treatments plus one control were pre-incubated at 40% water holding capacity (WHC) for four days. Then, they were brought to 80% WHC and 15N-nitrate was added (50 mg NO3-N kg-1 soil, 10% enriched in 15N). All treatments were set up with four replicates. In total, three cycles of (re)wetting - drying (80 to 40% WHC, total duration 20 days) were monitored. Samples for analyses of N2O concentrations and stable isotope signatures were taken daily (except for weekends) after closing the incubation vessels for 90 minutes. N2O emissions increased with each addition of water and decreased during drying to background values. Each rewetting led to larger emissions than measured in the previous cycle for all treatments including controls. All biochars decreased total N2O emissions compared to the control treatments. The higher the production temperature of the biochar, the larger usually the emission reduction. Largest effects were found for the grape wood and the Kontiki biochars. Interestingly, the addition of biochars also changed the isotopic signatures of the emitted N2O. Whereas emissions in the controls were enriched to about 5 atom% 15N excess at peak emissions, the enrichment was usually less after addition of biochars (1-5 atom% excess). Again, this effect tended to be larger at higher production temperatures of the

  18. Closed-loop 15N measurement of N2O and its isotopomers for real-time greenhouse gas tracing

    Science.gov (United States)

    Slaets, Johanna; Mayr, Leopold; Heiling, Maria; Zaman, Mohammad; Resch, Christian; Weltin, Georg; Gruber, Roman; Dercon, Gerd

    2016-04-01

    Quantifying sources of nitrous oxide is essential to improve understanding of the global N cycle and to develop climate-smart agriculture, as N2O has a global warming potential 300 times higher than CO2. The isotopic signature and the intramolecular distribution (site preference) of 15N are powerful tools to trace N2O, but the application of these methods is limited as conventional methods cannot provide continuous and in situ data. Here we present a method for closed-loop, real time monitoring of the N2O flux, the isotopic signature and the intramolecular distribution of 15N by using off-axis integrated cavity output spectroscopy (ICOS, Los Gatos Research). The developed method was applied to a fertilizer inhibitor experiment, in which N2O emissions were measured on undisturbed soil cores for three weeks. The treatments consisted of enriched urea-N (100 kg urea-N/ha), the same fertilizer combined with the nitrification inhibitor nitrapyrin (375 g/100 kg urea), and control cores. Monitoring the isotopic signature makes it possible to distinguish emissions from soil and fertilizer. Characterization of site preference could additionally provide a tool to identify different microbial processes leading to N2O emissions. Furthermore, the closed-loop approach enables direct measurement on site and does not require removal of CO2 and H2O. Results showed that 75% of total N2O emissions (total=11 346 μg N2O-N/m2) in the fertilized cores originated from fertilizer, while only 55% of total emissions (total=2 450 μg N2ON/m2) stemmed from fertilizer for the cores treated with nitrapyrin. In the controls, N2O derived from soil was only 40% of the size of the corresponding pool from the fertilized cores, pointing towards a priming effect on the microbial community from the fertilizer and demonstrating the bias that could be introduced by relying on non-treated cores to estimate soil emission rates, rather than using the isotopic signature. The site preference increased linearly

  19. Solar UV irradiation-induced production of N2O from plant surfaces - low emissions rates but all over the world.

    Science.gov (United States)

    Mikkelsen, T. N.; Bruhn, D.; Ambus, P.

    2016-12-01

    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-2 h-1, mostly due to the UV component. 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.

  20. Solar UV irradiation-induced production of N2O from plant surfaces - low emissions rates but all over the world

    DEFF Research Database (Denmark)

    Mikkelsen, Teis Nørgaard; Bruhn, Dan; Ambus, Per

    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-2 h-1, mostly due to the UV component. The emission rate is temperature dependent with a rather high activation energy...

  1. Parameters determining the use of zeolite 5A as collector medium in passive flux samplers to estimate N2O emissions from livestock sources.

    Science.gov (United States)

    Larios, Araceli D; Brar, Satinder Kaur; Ramírez, Antonio Avalos; Godbout, Stéphane; Sandoval-Salas, Fabiola; Palacios, Joahnn H; Dubé, Patrick; Delgado, Beatriz; Giroir-Fendler, Anne

    2017-05-01

    The present study analyzes the effect of parameters that determine the use of the zeolite 5A as collector medium in passive flux samplers (PFS) developed to estimate N 2 O emissions from livestock buildings. The study analyzes the mass of N 2 O collected on the zeolite 5A as a function of gas flow rate (40 and 130 ml/min), inlet mass of N 2 O to the PFS (from 7 to 84 μg), adsorbent mass (4 and 13.6 g), length of the adsorbent bed (1.9 and 10.9 cm), and inlet N 2 O concentration (0.6 and 2 ppmv). The mass of N 2 O collected on the zeolite 5A ranged from 1.24 to 6.19 μg of N 2 O/g of adsorbent, which was mainly affected by inlet N 2 O concentration and mass of adsorbent contained in the PFS. The mass of N 2 O collected presented a significant relationship with the inlet N 2 O concentration and the adsorbent bed. Tests were performed using PFS in a laboratory farm under semi-real conditions. It was found that at sampling time of 1.5 h, the accuracy and precision of PFS was appropriate. Under evaluated conditions, a maximum variation between PFS and direct detection of around 12% was estimated.

  2. Top-down constraints on global N2O emissions at optimal resolution: application of a new dimension reduction technique

    Science.gov (United States)

    Wells, Kelley C.; Millet, Dylan B.; Bousserez, Nicolas; Henze, Daven K.; Griffis, Timothy J.; Chaliyakunnel, Sreelekha; Dlugokencky, Edward J.; Saikawa, Eri; Xiang, Gao; Prinn, Ronald G.; O'Doherty, Simon; Young, Dickon; Weiss, Ray F.; Dutton, Geoff S.; Elkins, James W.; Krummel, Paul B.; Langenfelds, Ray; Steele, L. Paul

    2018-01-01

    We present top-down constraints on global monthly N2O emissions for 2011 from a multi-inversion approach and an ensemble of surface observations. The inversions employ the GEOS-Chem adjoint and an array of aggregation strategies to test how well current observations can constrain the spatial distribution of global N2O emissions. The strategies include (1) a standard 4D-Var inversion at native model resolution (4° × 5°), (2) an inversion for six continental and three ocean regions, and (3) a fast 4D-Var inversion based on a novel dimension reduction technique employing randomized singular value decomposition (SVD). The optimized global flux ranges from 15.9 Tg N yr-1 (SVD-based inversion) to 17.5-17.7 Tg N yr-1 (continental-scale, standard 4D-Var inversions), with the former better capturing the extratropical N2O background measured during the HIAPER Pole-to-Pole Observations (HIPPO) airborne campaigns. We find that the tropics provide a greater contribution to the global N2O flux than is predicted by the prior bottom-up inventories, likely due to underestimated agricultural and oceanic emissions. We infer an overestimate of natural soil emissions in the extratropics and find that predicted emissions are seasonally biased in northern midlatitudes. Here, optimized fluxes exhibit a springtime peak consistent with the timing of spring fertilizer and manure application, soil thawing, and elevated soil moisture. Finally, the inversions reveal a major emission underestimate in the US Corn Belt in the bottom-up inventory used here. We extensively test the impact of initial conditions on the analysis and recommend formally optimizing the initial N2O distribution to avoid biasing the inferred fluxes. We find that the SVD-based approach provides a powerful framework for deriving emission information from N2O observations: by defining the optimal resolution of the solution based on the information content of the inversion, it provides spatial information that is lost when

  3. CO2, CH4 and N2O fluxes from soil of a burned grassland in Central Africa

    Directory of Open Access Journals (Sweden)

    R. Valentini

    2010-11-01

    Full Text Available The impact of fire on soil fluxes of CO2, CH4 and N2O was investigated in a tropical grassland in Congo Brazzaville during two field campaigns in 2007–2008. The first campaign was conducted in the middle of the dry season and the second at the end of the growing season, respectively one and eight months after burning. Gas fluxes and several soil parameters were measured in each campaign from burned plots and from a close-by control area preserved from fire. Rain events were simulated at each campaign to evaluate the magnitude and duration of the generated gas flux pulses. In laboratory experiments, soil samples from field plots were analysed for microbial biomass, net N mineralization, net nitrification, N2O, NO and CO2 emissions under different water and temperature soil regimes. One month after burning, field CO2 emissions were significantly lower in burned plots than in the control plots, the average daily CH4 flux shifted from net emission in the unburned area to net consumption in burned plots, no significant effect of fire was observed on soil N2O fluxes. Eight months after burning, the average daily fluxes of CO2, CH4 and N2O measured in control and burned plots were not significantly different. In laboratory, N2O fluxes from soil of burned plots were significantly higher than fluxes from soil of unburned plots only above 70% of maximum soil water holding capacity; this was never attained in the field even after rain simulation. Higher NO emissions were measured in the lab in soil from burned plots at both 10% and 50% of maximum soil water holding capacity. Increasing the incubation temperature from 25 °C to 37 °C negatively affected microbial growth, mineralization and nitrification activities but enhanced N2O and CO2 production. Results indicate that fire did not increase post-burning soil GHG emissions in this tropical grasslands characterized by acidic, well drained and nutrient-poor soil.

  4. Modelling site-specific N2O emission factors from Austrian agricultural soils for targeted mitigation measures (NitroAustria)

    Science.gov (United States)

    Amon, Barbara; Zechmeister-Boltenstern, Sophie; Kasper, Martina; Foldal, Cecilie; Schiefer, Jasmin; Kitzler, Barbara; Schwarzl, Bettina; Zethner, Gerhard; Anderl, Michael; Sedy, Katrin; Gaugitsch, Helmut; Dersch, Georg; Baumgarten, Andreas; Haas, Edwin; Kiese, Ralf

    2016-04-01

    Results from a previous project "FarmClim" highlight that the IPCC default emission factor is not able to reflect region specific N2O emissions from Austrian arable soils. The methodology is limited in identifying hot spots and hot moments of N2O emissions. When estimations are based on default emission factors no recommendations can be given on optimisation measures that would lead to a reduction of soil N2O emissions. The better the knowledge is about Nitrogen and Carbon budgets in Austrian agricultural managed soils the better the situation can be reflected in the Austrian GHG emission inventory calculations. Therefore national and regionally modelled emission factors should improve the evidence for national deviation from the IPCC default emission factors and reduce the uncertainties. The overall aim of NitroAustria is to identify the drivers for N2O emissions on a regional basis taking different soil types, climate, and agricultural management into account. We use the LandscapeDNDC model to update the N2O emission factors for N fertilizer and animal manure applied to soils. Key regions in Austria were selected and region specific N2O emissions calculated. The model runs at sub-daily time steps and uses data such as maximum and minimum air temperature, precipitation, radiation, and wind speed as meteorological drivers. Further input data are used to reflect agricultural management practices, e.g., planting/harvesting, tillage, fertilizer application, irrigation and information on soil and vegetation properties for site characterization and model initialization. While at site scale, arable management data (crop cultivation, rotations, timings etc.) is obtained by experimental data from field trials or observations, at regional scale such data need to be generated using region specific proxy data such as land use and management statistics, crop cultivations and yields, crop rotations, fertilizer sales, manure resulting from livestock units etc. The farming

  5. Advances in the catalysts development in base of mixed oxides for control reactions of N2O

    International Nuclear Information System (INIS)

    Garcia, M.A.; Perez, R.; Gomez, A.; Diaz, G.

    2000-01-01

    The catalytic supports Al 2 O 3 , La 2 O 3 and Al 2 O 3 -La 2 O 3 were prepared by the precipitation and coprecipitation techniques. The catalytic supports Al 2 O 3 , La 2 O 3 and Al 2 O 3 -La 2 O 3 were characterized by several techniques for to determine texture (BET), crystallinity (XRD), chemical composition (SEM), FTIR and it was evaluated their total acidity by the reaction with 2-propanol. It was continued with the cobalt addition by Impregnation and coprecipitation and it was evaluated its catalytic activity in the N 2 O decomposition reaction. Also it was realized the N 2 O reduction with Co using these catalysts. (Author)

  6. Field emissions of N2O during biomass production may affect the sustainability of agro-biofuels

    DEFF Research Database (Denmark)

    Carter, Mette Sustmann; Hauggaard-Nielsen, Henrik; Heiske, Stefan

    One way of reducing the emissions of fossil fuel‐derived CO2 is to replace fossil fuels with biofuels produced from agricultural biomasses or residuals. However, cultivation of soils results in emission of other greenhouse gasses, especially nitrous oxide (N2O). Previous studies have shown...... relate measured field emissions of N2O to the reduction in fossil fuel‐derived CO2, which is obtained when agricultural biomasses are used for biofuel production. The analysis includes five organically managed crops (viz. maize, rye, rye‐vetch, vetch and grass‐clover) and three scenarios for conversion...... and biogas or by biogas alone produced from either fresh grass‐clover or whole crop maize. Here the net reduction corresponded to about 8 tons CO2 ha‐1 yr‐1....

  7. Seasonal CH4 and N2O emissions and plant growth characteristics of several cultivars in direct seeded rice systems

    Science.gov (United States)

    Simmonds, M.; Anders, M. M.; Adviento-Borbe, M. A.; Van Kessel, C.; McClung, A.; Linquist, B.

    2014-12-01

    Understanding cultivar effects on field greenhouse gas (GHG) emissions in rice (Oryza sativa L.) systems is needed to improve the accuracy of predictive models used for estimating GHG emissions, and to determine to what extent choice of cultivar may have on GHG mitigation. We compared CH4 and N2O emissions, global warming potential (GWP = N2O + CH4), yield-scaled GWP (GWPY = GWP Mg-1 grain), and plant growth characteristics of 8 cultivars within 4 study sites in California and Arkansas. Seasonal CH4 emissions differed between cultivars by a factor of 2.1 and 1.3 at one California and one Arkansas site, respectively. Nitrous oxide emissions were negligible, comprised food security.

  8. Model simulation of changes in N2O and NO emissions with conversion of tropical rain forests to pastures in the Costa Rican Atlantic Zone

    Science.gov (United States)

    Liu, Shuguang; Reiners, William A.; Keller, Michael; Schimel, David S.

    1999-06-01

    Nitrous oxide (N2O) and nitric oxide (NO) are among the trace gases of concern because of their importance in global climate and atmospheric chemistry. Modeling techniques are needed for simulating the spatial and temporal dynamics of N2O and NO emissions from soils into the atmosphere. In this study, we modified the ecosystem model CENTURY to simulate changes in N2O and NO soil emissions through the process of converting tropical moist forests to pastures in the Atlantic Lowlands of Costa Rica. Measurements of water-filled pore space (WFPS) and fluxes of N2O and NO from a chronosequence of pastures were used for calibration and testing of the model. It was found that the N2O+NO — WFPS and N2O:NO — WFPS relationships as developed from primary forests could be generalized to the chronosequence of pastures and other land use systems in the region. Modeled net increases (compared to primary forests) in total N2O and NO production after conversion from forest to pasture were 514 kg N ha-1 during the first 15 years under normal field conditions. The nitrogen loss in the form of N2O and NO during the first 15 years could range from 401 to 548 kg N ha-1, depending on the amounts of forest residue remaining on pasture sites. N2O-N accounted for 90% of the gas fluxes, while NO-N accounted for 10%. Sensitivity analysis indicated that the impacts of forest-pasture conversion on N2O and NO emissions from soil into the atmosphere were complex, depending on the initial conditions of the forest-derived pastures, management practices, soil physical and chemical conditions and their changes over time, N availability, and climate. It is therefore important to incorporate the spatial and temporal heterogeneities of those controlling factors in estimating regional and global N2O and NO emissions from soils into the atmosphere.

  9. Simulating response of N2O emissions to fertiliser N application and climatic variability from a rain-fed and wheat-cropped soil in Western Australia.

    Science.gov (United States)

    Li, Yong; Barton, Louise; Chen, Deli

    2012-03-30

    Besides land management and soil properties, nitrous oxide (N(2)O) emissions from the soil may be responsive to climatic variation. In this study the Water and Nitrogen Management Model (WNMM) was calibrated and validated to simulate N(2)O emissions from a rain-fed and wheat-cropped system on a sandy duplex soil at Cunderdin, Western Australia, from May 2005 to May 2007, then it was deployed to simulate N(2)O emissions for seven scenarios of fertiliser N application under various climatic conditions (1970-2006). The WNMM satisfactorily simulated crop growth, soil water content and mineral N contents of the surface soil (0-10 cm), soil temperatures at depths and N(2)O emissions from the soil compared with field observations in two fertiliser treatments during calibration and validation. About 70% of total N(2)O emissions were estimated as nitrification-induced. The scenario analysis indicated that the WNMM-simulated annual N(2)O emissions for this rain-fed and wheat-cropped system were significantly correlated with annual average minimum air temperature (r = 0.21), annual pan evaporation (r = 0.20) and fertiliser N application rate (r = 0.80). Both annual rainfall and wheat yield had weak and negative correlations with annual N(2)O emissions. Multiple linear regression models for estimating annual N(2)O emissions were developed to account for the impacts of climatic variation (including temperature and rainfall), fertiliser N application and crop yield for this rain-fed and wheat-cropped system in Western Australia, which explained 64-74% of yearly variations of the WNMM-estimated annual N(2) O emissions. The WNMM was tested and capable of simulating N(2) O emissions from the rain-fed and wheat-cropped system. The inclusion of climatic variables as predictors in multiple linear regression models improved their accuracy in predicting inter-annual N(2)O emissions. Copyright © 2011 Society of Chemical Industry.

  10. Co-composting of municipal solid waste mixed with matured sewage sludge: The relationship between N2O emissions and denitrifying gene abundance.

    Science.gov (United States)

    Bian, Rongxing; Sun, Yingjie; Li, Weihua; Ma, Qiang; Chai, Xiaoli

    2017-12-01

    Aerobic composting is an alternative measure to the disposal of municipal solid waste (MSW). However, it produces nitrous oxide (N 2 O), a highly potent greenhouse via microbial nitrification and denitrification. In this study, the effects of matured sewage sludge (MSS) amendment on N 2 O emissions and the inter-relationships between N 2 O emissions and the abundance of denitrifying bacteria were investigated during aerobic composting of MSW. The results demonstrated that MSW composting with MSS amendments (C1, and C2, with a MSW to MSS ratio of 2:1 and 4:1, (v/v), respectively) significantly increased N 2 O emissions during the initial stage, yet contributed to the mitigation of N 2 O emissions during the cooling and maturation stage. MSS amended composting emitted a total of 18.4%-25.7% less N 2 O than the control treatment without MSS amendment (CK). Matured sewage sludge amendment also significantly altered the abundance of denitrifying bacteria. The quantification of denitrifying functional genes revealed that the N 2 O emission rate had a significant positive correlation with the abundance of the nirS, nirK genes in both treatments with MSS amendment. The nosZ/(nirS + nirK) ratio could be a good indicator for predicting N 2 O emissions. The higher N 2 O emission rate during the initial stage of composting mixed with MSS was characterized by lower nosZ/(nirS + nirK) ratios, compared to CK treatment. Higher ratios of nosZ/(nirS + nirK) were measured during the cooling and maturation stage in treatments with MSS which resulted in a reduction of the N 2 O emissions. These results demonstrated that MSS amendment could be a valid strategy for mitigating N 2 O emissions during MSW composting. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Impacts of Nitrogen Removal and Re-Application on N2O fluxes from Narragansett Bay: Contrasting Turfgrasses, Salt Marshes, and Wastewater Treatment Systems

    Science.gov (United States)

    Brannon, E.; Moseman-Valtierra, S.; Quinn, R. K.; Amador, J.; Brown, R.; Lancellotti, B.; Glennon, K.; Celeste, G.; Craver, V.

    2016-12-01

    Narragansett Bay in Rhode Island is characterized by a substantial, historic bay-wide nitrogen (N) gradient. Centralized wastewater treatment plants (WWTPs) are a major anthropogenic N source. Onsite wastewater treatments systems (OWTS), which serve 1/3 of all households in the state, are another anthropogenic N source. Recent state regulation has prompted upgrades to both WWTPs and OWTS to increase N removal capacities. Although this should lower N loads to Narragansett Bay, it has the potential to increase the flux of nitrous oxide (N2O), a potent greenhouse gas. We measured summer-time (2016) N2O fluxes of a major WWTP (biological N removal system at Field's Point in Providence) and three of the most common advanced OWTS in the Narragansett Bay watershed (Orenco Advantex AX20, BioMicrobics FAST, SeptiTech D Series). We also tested impacts of application of recovered N (biosolids from wastewater sludge) on N2O fluxes from a turfgrass (Schedonerus arundinaceus) and dominant native coastal cordgrass (Spartina alterniflora) in mesocosm experiments. Preliminary results indicate that the largest N2O fluxes (245 ± 72 µmol N2O m-2 h-1) were from the Field's Point WWTP. Significant, but smaller N2O fluxes (6 ± 3 µmol N2O m-2 h-1 were also measured from the OWTS. In contrast, N2O fluxes from the N-enriched native coastal cordgrass and turfgrass mesocosms were often non-detectable. However, fluxes from a few mesocosms (max. of 25 µmol N2O m-2 h-1) were on the same order of magnitude as fluxes from the OWTS. A state-wide budget of N2O emissions from turfgrasses, intertidal marshes, and OWTS will be estimated to determine their significance as sources relative to the Field's Point WWTP. This data will be used to identify areas where N2O fluxes can be minimized in the state of RI.

  12. Phosphorus addition mitigates N2O and CH4 emissions in N-saturated subtropical forest, SW China

    Directory of Open Access Journals (Sweden)

    L. Yu

    2017-06-01

    Full Text Available Chronically elevated nitrogen (N deposition has led to severe nutrient imbalance in forest soils. Particularly in tropical and subtropical forest ecosystems, increasing N loading has aggravated phosphorus (P limitation of biomass production, and has resulted in elevated emissions of nitrous oxide (N2O and reduced uptake of methane (CH4, both of which are important greenhouse gases. Yet, the interactions of N and P and their effects on greenhouse gas emissions remain elusive. Here, we report N2O and CH4 emissions together with soil N and P data for a period of 18 months following a single P addition (79 kg P ha−1, as NaH2PO4 powder to an N-saturated, Masson pine-dominated forest soil at TieShanPing (TSP, Chongqing, south-western (SW China. We observed a significant decline in both nitrate (NO3− concentrations in soil water (5 and 20 cm depths and in soil N2O emissions, following P application. We hypothesise that enhanced N uptake by plants in response to P addition, resulted in less available NO3− for denitrification. By contrast to most other forest ecosystems, TSP is a net source of CH4. P addition significantly decreased CH4 emissions and turned the soil from a net source into a net sink. Based on our observation and previous studies in South America and China, we believe that P addition relieves N inhibition of CH4 oxidation. Within the 1.5 years after P addition, no significant increase of forest growth was observed and P stimulation of forest N uptake by understorey vegetation remains to be confirmed. Our study indicates that P fertilisation of N-saturated, subtropical forest soils may mitigate N2O and CH4 emissions, in addition to alleviating nutrient imbalances and reducing losses of N through NO3− leaching.

  13. Investigating the microbial community responsible for unusually high soil N2O and NOx emissions in the Colorado Desert

    Science.gov (United States)

    Eberwein, J. R.; Carey, C.; Aronson, E. L.; Jenerette, D.

    2016-12-01

    Although the importance of soil nitrogenous emissions are well accepted in terms of local and global ecological relevance, there remain considerable knowledge gaps concerning the mechanisms regulating production, particularly in arid systems. This study aimed to connect desert soil trace gas emissions of nitrous oxide (N2O) and nitrogen oxides (NOx) with compositional changes in the microbial community. We quantified real-time soil trace gas emissions at two sites in the Colorado Desert experiencing contrasting anthropogenic nitrogen (N) deposition loads (characterize the soil microbial community. N2O fluxes reached as high as 1200 ng N2O-N m-2 s-1, well above most published emissions, but returned to pre-wetting conditions within 12 hours. NOx emissions reached as high as 350 ng NOx-N m-2 s-1 and remained elevated past 24 hours post-wetting. Results from the 16S analysis indicate distinct differences in the microbial community composition between the high and low N deposition sites, with less than 50% of operational taxonomic units (OTUs) in common between sites. N addition had a significant effect on the soil microbial community at the low deposition site, but not at the high deposition site. Furthermore, significant shifts in the bacterial community occurred after wetting, with only one third of the community remaining constant between time points. These results suggest that gaseous N export, particularly N2O emission, is a greater form of nitrogen loss in this system than is currently assumed. Experimental N additions and anthropogenic N deposition show potential for shifting soil microbial community composition, with implications for soil N emissions. Furthermore, shifts in the microbial community can occur as quickly as 15 minutes post-wetting, representing a remarkable ability for soil microorganisms to recover from extreme water stress. As aridlands cover approximately one third of the Earth's land surface, understanding the mechanisms that contribute to

  14. Temporal Variability of N2O and CH4 in Coastal Sediments: Assessing the Impact of Organic Matter Inputs

    Science.gov (United States)

    Burgos, M.; Ortega, T.; Forja, J. M.

    2016-02-01

    N2O and CH4 contribute respectively, about 5-6% and 15% to the anthropogenic greenhouse effect. Coastal areas are potential sources of those gases, which can be produced in sediments from organic matter (OM) degradation. Oxygen microprofiles, sediment organic nitrogen and carbon content, and pore-water concentrations of N2O, CH4 and nutrients were measured in sediment from three marine systems ending in Cadiz Bay (SW Spain) in order to identify the OM diagenetic pathways. Hydrodynamic characteristics of the studied environments (Guadalete River estuary, Sancti Petri Channel and San Pedro Creek) are different, even though they all are shallow and tidally affected. The area holds a high population density receiving large amount of OM from both, urban sources and primary sector activities. Significant differences (pGuadalete Estuary were 3 orders of magnitude higher at the OM contaminated station (reaching 8.3 mmol m-2 d-1) than at the station located farther away (fluxes varied between 1.2 and 3.4 μmol m-2 d-1). Sediments in the Estuary were also a source of N2O to the water column (range: 2.1 - 111.2 μmol m-2 d-1), however sediments of the two other marine systems were N2O sinks or weak sources (range: -2.5 - 0.2 μmol m-2 d-1). Results highlight the complexity of the OM diagenesis under different physical and biogeochemical conditions that consequently affects the sediment-water fluxes.

  15. Theoretical study of 14N quadrupole coupling constants in some NO-containing complexes: N2O3 and FNO

    Czech Academy of Sciences Publication Activity Database

    Polák, Rudolf; Fišer, J.

    2008-01-01

    Roč. 351, 1-3 (2008), s. 83-90 ISSN 0301-0104 R&D Projects: GA AV ČR 1ET400400410; GA AV ČR IAA400400504 Institutional research plan: CEZ:AV0Z40400503 Keywords : dinitrogen trioxide * N2O3 * nitrosyl fluoride * FNO Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.961, year: 2008

  16. Characterization of N2O emission and associated bacterial communities from the gut of wood-feeding termite Nasutitermes voeltzkowi.

    Science.gov (United States)

    Majeed, Muhammad Zeeshan; Miambi, Edouard; Riaz, Muhammad Asam; Brauman, Alain

    2015-09-01

    Xylophagous termites rely on nitrogen deficient foodstuff with a low C/N ratio. Most research work has focused on nitrogen fixation in termites highlighting important inflow and assimilation of atmospheric nitrogen into their bodies fundamentally geared up by their intestinal microbial symbionts. Most of termite body nitrogen is of atmospheric origin, and microbially aided nitrification is the principal source of this nitrogen acquisition, but contrarily, the information regarding potent denitrification process is very scarce and poorly known, although the termite gut is considered to carry all favorable criteria necessary for microbial denitrification. Therefore, in this study, it is hypothesized that whether nitrification and denitrification processes coexist in intestinal milieu of xylophagous termites or not, and if yes, then is there any link between the denitrification product, i.e., N2O and nitrogen content of the food substrate, and moreover where these bacterial communities are found along the length of termite gut. To answer these questions, we measured in vivo N2O emission by Nasutitermes voeltzkowi (Nasutitermitinae) maintained on different substrates with varying C/N ratio, and also, molecular techniques were applied to study the diversity (DGGE) and density (qPCR) of bacterial communities in anterior and posterior gut portions. Rersults revealed that xylophagous termites emit feeble amount of N2O and molecular studies confirmed this finding by illustrating the presence of an ample density of N2O-reductase (nosZ) gene in the intestinal tract of these termites. Furthermore, intestinal bacterial communities of these termites were found more dense and diverse in posterior than anterior portion of the gut.

  17. Effect of Precursor Synthesis on Catalytic Activity of Co3O4 in N2O Decomposition.

    Czech Academy of Sciences Publication Activity Database

    Chromčáková, Ž.; Obalová, L.; Kovanda, F.; Legut, D.; Titov, A.; Ritz, M.; Fridrichová, D.; Michalik, S.; Kustrowski, P.; Jirátová, Květa

    2015-01-01

    Roč. 257, Part 1 (2015), s. 18-25 ISSN 0920-5861. [AWPAC2014 - International Symposium on Air & Water Pollution Abatement Catalysis. Krakow, 01.09.2014-05.09.2014] R&D Projects: GA ČR GA14-13750S Institutional support: RVO:67985858 Keywords : cobalt spinel * Co3O4 * N2O decomposition * precursor synthesis Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 4.312, year: 2015

  18. Low-energy proton stopping power of N2, O2 and water vapor and deviations from Bragg's rule

    Science.gov (United States)

    Xu, Y. J.; Khandelwal, G. S.; Wilson, J. W.

    1984-01-01

    A modified local plasma model, based on the works of Lindhard and Winther; and Bethe, Brown, and Walske, is established. The Gordon-Kim model for molecular electron density is used to calculate stopping power of N2, O2, and water vapor for protons of energy ranging from 40 keV to 2.5 MeV, resulting in good agreement with experimental data. Deviations from Bragg's rule are evaluated and are discussed under the present theoretical model.

  19. Coastal upwelling fluxes of O2, N2O, and CO2 assessed from continuous atmospheric observations at Trinidad, California

    Directory of Open Access Journals (Sweden)

    T. J. Lueker

    2004-01-01

    Full Text Available Continuous atmospheric records of O2/N2, CO2 and N2O obtained at Trinidad, California document the effects of air-sea exchange during coastal upwelling and plankton bloom events. The atmospheric records provide continuous observations of air-sea fluxes related to synoptic scale upwelling events over several upwelling seasons. Combined with satellite, buoy and local meteorology data, calculated anomalies in O2/N2 and N2O were utilized in a simple atmospheric transport model to compute air-sea fluxes during coastal upwelling. CO2 fluxes were linked to the oceanic component of the O2 fluxes through local hydrographic data and estimated as a function of upwelling intensity (surface ocean temperature and wind speed. Regional air-sea fluxes of O2/N2, N2O, and CO2 during coastal upwelling were estimated with the aid of satellite wind and SST data. Upwelling CO2 fluxes were found to represent ~10% of export production along the northwest coast of North America. Synoptic scale upwelling events impact the net exchange of atmospheric CO2 along the coastal margin, and will vary in response to the frequency and duration of alongshore winds that are subject to climate change.

  20. Tracer-tracer relationships and lower stratospheric dynamics: CO2 and N2O correlations during SPADE

    Science.gov (United States)

    Boering, Kristie A.; Daube, Bruce C.; Wofsy, Steven C.; Loewenstein, Max; Podolske, James R.; Keim, Eric R.

    1994-01-01

    Simultaneous measurements of CO2 and N2O from the NASA ER-2 aircraft during SPADE deployments in November 1992, April/May 1993, and October 1993 provide new information on transport rates in the lower stratosphere. The tropospheric seasonal cycle in CO2, superimposed on the long-term trend, is observed to propagate into the statosphere. The compact correlations observed between CO2 and N2O indicate that meridional transport is sufficiently rapid to create a uniform set of relationships over the northern hemisphere up to at least 21 km even though CO2 changes significantly on a time scale of 8 to 12 weeks. the observed seasonal dependence of the correlations indicates that vertical transport above 20 km is slower in northern summer than in winter and slow throughout the year between 19 km and the tropopause. The inferred amplitude of the seasonal CO2 oscillation in the statopshere, viewed relative to N2O, places constraints on the mean latitude for air entering the statosphere.

  1. Emissions of CH4, N2O, NH3 and odorants from pig slurry during winter and summer storage

    DEFF Research Database (Denmark)

    Petersen, Søren O; Dorno, Nadia; Lindholst, Sabine

    2013-01-01

    eq m−3 day−1 during a 45-day winter storage, and 1.1–1.3 kg CO2 eq m−3 day−1 during a 58-day summer storage period independent of storage conditions; the GHG balance was dominated by CH4 emissions. Nitrous oxide emissions occurred only during summer storage where, apparently, emissions were related......Manure storage contributes significantly to greenhouse gas (GHG), NH3 and odour emissions from intensive livestock production. A pilot-scale facility with eight 6.5-m3 slurry storage units was used to quantify emissions of CH4, N2O, NH3, and odorants from pig slurry during winter and summer storage...... to the water balance of the surface crust. An N2O emission factor for slurry storage with a straw crust was estimated at 0.002–0.004. There was no evidence for a reduction of CH4 emissions with a crust. Current Intergovernmental Panel on Climate Change recommendations for N2O and CH4 emission factors...

  2. Bimetallic Rh-Fe catalysts for N2O decomposition: effects of surface structures on catalytic activity.

    Science.gov (United States)

    Chen, Hao; Lu, Qinghua; Yi, Chunhai; Yang, Bolun; Qi, Suitao

    2018-02-14

    Well-homogenized RhFe alloy nanoparticles and core-shell structured Fe@Rh nanoparticles were highly dispersed on SBA-15 and then applied to N 2 O catalytic conversion. Compared to RhFe/SBA-15, Fe@Rh/SBA-15 showed a higher catalytic activity for N 2 O decomposition. This is because the Rh layers covering the Fe core were able to protect against oxidization and so Fe@Rh/SBA-15 was prevented from deactivating. DFT calculations were performed to study the reaction mechanism of N 2 O decomposition. The rate-determining step, which was found to be the formation of O 2 from adsorbed oxygen atoms on the surfaces of RhFe and Fe@Rh, revealed that O atoms prefer to be adsorbed on exposed Fe atoms on the surface of RhFe rather than that of Fe@Rh. The calculation results indicate that the exposed Fe atoms tend to be oxidized on the surface of RhFe, resulting in the deactivation of RhFe/SBA-15 during the experiment.

  3. Annual balances of CH4 and N2O from a managed fen meadow using eddy covariance flux measurements

    International Nuclear Information System (INIS)

    Schrier-Uijl, A.P.; Veenendaal, E.M.; Kroon, P.S.; Hensen, A.; Jonker, H.J.J.

    2010-10-01

    Annual terrestrial balances of methane (CH4) and nitrous oxide (N2O) are presented for a managed fen meadow in the Netherlands for 2006, 2007 and 2008, using eddy covariance (EC) flux measurements. Annual emissions derived from different methods are compared. The most accurate annual CH4 flux is achieved by gap filling EC fluxes with an empirical multivariate regression model, with soil temperature and mean wind velocity as driving variables. This model explains about 60% of the variability in observed daily CH4 fluxes. Annual N2O emissions can be separated into background emissions and event emissions due to fertilization. The background emission is estimated using a multivariate regression model also based on EC flux data, with soil temperature and mean wind velocity as driving variables. The event emissions are estimated using emission factors. The minimum direct emission factor is derived for six fertilization events by subtracting the background emission, and the IPCC default emission factor of 1% is used for the other events. In addition, the maximum direct emission factors are determined for the six events without subtracting the background emission. The average direct emission factor ranges from 1.2 to 2.8%, which is larger than the IPCC default value. Finally, the total terrestrial greenhouse gas balance is estimated at 16 Mg ha -1 year -1 in CO2-equivalents with contributions of 30, 25 and 45% by CO2, CH4 and N2O, respectively.

  4. Highly active and stable ion-exchanged Fe–Ferrierite catalyst for N2O decomposition under nitric acid tail gas conditions

    NARCIS (Netherlands)

    Melián-Cabrera, I.; Mentruit, C.; Pieterse, J.A.Z.; Brink, R.W. van den; Mul, G.; Kapteijn, F.; Moulijn, J.A.

    2005-01-01

    This communication reports on the excellent performance and durability of a wet ion-exchanged Fe–Ferrierite catalysts for N2O decomposition under conditions of nitric acid plants, especially in the presence of water (0.5% vol) and at a high space time W/F0(N2O) = 900 kgcat s mol-1. In contrast to

  5. Liebig's law of the minimum applied to a greenhouse gas: Alleviation of P-limitation reduces soil N2O emmission

    NARCIS (Netherlands)

    Baral, B.R.; Kuyper, T.W.; Groenigen, van J.W.

    2014-01-01

    Emission of the greenhouse gas (GHG) nitrous oxide (N2O) are strongly affected by nitrogen (N) fertilizer application rates. However, the role of other nutrients through stoichiometric relations with N has hardly been studied. We tested whether phosphorus (P) availability affects N2O emission. We

  6. The use of ketamine or etomidate to supplement sufentanil/N2O anesthesia does not disrupt monitoring of myogenic transcranial motor evoked responses

    NARCIS (Netherlands)

    Ubags, L. H.; Kalkman, C. J.; Been, H. D.; Porsius, M.; Drummond, J. C.

    1997-01-01

    Intraoperative monitoring of myogenic transcranial motor evoked responses (tc-MERs) requires an anesthetic technique that minimally depresses response amplitudes. Acceptable results have been obtained during opioid/N2O anesthesia, provided that the concentration of N2O does not exceed 50%. However,

  7. N2O release from agro-biofuel production negates global warming reduction by replacing fossil fuels

    Directory of Open Access Journals (Sweden)

    A. R. Mosier

    2008-01-01

    Full Text Available The relationship, on a global basis, between the amount of N fixed by chemical, biological or atmospheric processes entering the terrestrial biosphere, and the total emission of nitrous oxide (N2O, has been re-examined, using known global atmospheric removal rates and concentration growth of N2O as a proxy for overall emissions. For both the pre-industrial period and in recent times, after taking into account the large-scale changes in synthetic N fertiliser production, we find an overall conversion factor of 3–5% from newly fixed N to N2O-N. We assume the same factor to be valid for biofuel production systems. It is covered only in part by the default conversion factor for "direct" emissions from agricultural crop lands (1% estimated by IPCC (2006, and the default factors for the "indirect" emissions (following volatilization/deposition and leaching/runoff of N: 0.35–0.45% cited therein. However, as we show in the paper, when additional emissions included in the IPCC methodology, e.g. those from livestock production, are included, the total may not be inconsistent with that given by our "top-down" method. When the extra N2O emission from biofuel production is calculated in "CO2-equivalent" global warming terms, and compared with the quasi-cooling effect of "saving" emissions of fossil fuel derived CO2, the outcome is that the production of commonly used biofuels, such as biodiesel from rapeseed and bioethanol from corn (maize, depending on N fertilizer uptake efficiency by the plants, can contribute as much or more to global warming by N2O emissions than cooling by fossil fuel savings. Crops with less N demand, such as grasses and woody coppice species, have more favourable climate impacts. This analysis only considers the conversion of biomass to biofuel. It does not take into account the use of fossil fuel on the farms and for fertilizer and pesticide production, but it also neglects the production of useful co-products. Both factors

  8. Greenhouse Gas (CH4, CO2 and N2O) Emission Levels by Wastewater Treatment Plant (WWTP) Ponds in Brazil

    Science.gov (United States)

    Rossete, A. L. M.; Sundefeld Junior, G.; Aparicio, C.; Baldi, G. G.; Montes, C. R.; Piveli, R. P.; Melfi, A. J.

    2015-12-01

    This study measured greenhouse gas emissions (GHG) by Facultative Ponds on Wastewater Treatment Plants. The most studied GHGs include CO2, CH4and N2O. The level of GHG (CO2, CH4 and N2O) emissions by WWTPs in Australian-type stabilization ponds was measured in the city of Lins (22º21'S, 49º50'W), state of São Paulo (SP), Brazil. GHG collection was carried outusing a collection chamber installed at the center of the facultative pond's final third. The effluent's pH and temperature (ET) were registered by probes, and meteorological information regarding air temperature (AT) and solar radiation (SR) were obtained from INMET, Brazil. GHG collection was carried out for 72 consecutive hours in June 2014, on an hourly basis, once every 5 minutes, for the first 30 minutes, and once every 10 minutes from 30 to 50 minutesand subsequently analyzed by gas chromatograph (GC).After three days of data collection, the average AT, SR, ET and pH values were, respectively, 18oC, 2583kJm-2, 23oC and 8.2. Average values for GHG emission levels (CH4, CO2 and N2O) were 79.01; 100.65 and 0.0 mg m-2 h-1, respectively. GHG emission levels were divided into light periods (morning, afternoon and evening)in order to verify the periods with the highest GHG emissions.The highest CH4 emission levels were measured between morning and early afternoon. The maximum CO2 emissions were observed from evening to early morning. N2O emissions were constant and values were close to the ones found in the atmosphere, which shows the emission of N2O by facultative ponds does not contribute to greenhouse gases emissions.The results enabled us to characterize and quantify GHG emission levels per Facultative Pond on Wastewater Treatment Plant. Acknowledgment to FAPESP and SABESP, Brazil.

  9. Substantial N2O emissions from peat decomposition and N fertilization in an oil palm plantation exacerbated by hotspots

    Science.gov (United States)

    Oktarita, Satria; Hergoualc'h, Kristell; Anwar, Syaiful; Verchot, Louis V.

    2017-10-01

    It is unclear to what extent emissions of nitrous oxide (N2O) from drained histosols in the tropics may contribute to the atmospheric burden of greenhouse gases. In particular, there is a critical need to elucidate their magnitude in oil palm plantations on these soils. We examined spatio-temporal variations of N2O emissions from peat decomposition and nitrogen (N) fertilization in a plantation trial in Sumatra, which included three application rates: 0 (N0), 153 (N1) and 306 (N2) kg N ha-1 y-1. The spatially stratified sampling design distinguished the area around the palms which received fertilizer (9% of the surface) from the rest of the plot which was unfertilized. Annual emissions were substantial with rates of 22.1 ± 5.7, 12.8 ± 2.7 and 26.6 ± 5.7 kg N2O-N ha-1 in the N0, N1 and N2 treatments, respectively. These equal 9.3 ± 2.4, 5.4 ± 1.1 and 11.2 ± 2.4 Mg CO2eq ha-1 y-1, or 5-10 times emission rates in natural peatland forest. The site exhibited two persistent hotspots located in the unfertilized zone, contributing 33 and 46% of annual emissions in N0 and N2 while representing only 10% of the area sampled. The response of emissions to fertilization was exponential but restricted to the small N application area. At the plot scale and over the year, the impact of fertilized-induced emissions was minimal due to the prevalence of emissions from peat decomposition. Annual rates among treatments were similar when discarding the contribution of hotspots to evaluate N addition effect. High N2O emissions from peat decomposition in the tropics tend to be common within the restricted existing literature; which is in contrast with most recent IPCC emission factors. Our results emphasize the importance to integrate N2O emissions in greenhouse gas budgets of plantations on peat, despite the predominance of CO2 in total emissions.

  10. Estimates of N2O, NO and NH3 Emissions From Croplands in East, Southeast and South Asia

    Science.gov (United States)

    Yan, X.; Ohara, T.; Akimoto, H.

    2002-12-01

    Agricultural activities have greatly altered the global nitrogen cycle and produced nitrogenous gases of environmentally significance. More than half of the global chemical nitrogen fertilizer is used for crop production in East, Southeast and South Asia where rice the center of nutrition. Emissions of nitrous oxide (N2O), nitric oxide (NO) and ammonia (NH3) from croplands in this region were estimated by considering both background emission and emissions resulted from nitrogen added to croplands, including chemical nitrogen, animal manure used as fertilizer, biological fixed nitrogen and nitrogen in crop residue returned to field. Background emission fluxes of N2O and NO from croplands were estimated at 1.16 and 0.52 kg N ha-1yr-1, respectively. A fertilizer-induced N2O emission factor of 1.25% for upland was adopted from IPCC guidelines, and a factor of 0.25% was derived for paddy field from measurements. Total N2O emission from croplands in the region was estimated at 1.16 Tg N yr-1, with 41% contributed by background emission which was not considered in previous global estimates. However, the average fertilizer-induced N2O emission is only 0.93%, lower than the default IPCC value of 1.25% due to the low emission factor from paddy field. A fertilizer-induced NO emission factor of 0.66% for upland was derived from field measurements, and a factor of 0.13% was assumed for paddy field. Total NO emission was 572 Gg N yr-1 in the region, with 38% due to background emission. Average fertilizer-induce NO emission factor was 0.48%. Extrapolating this estimate to global scale will result in a global NO emission from cropland of 1.6 Tg N yr-1, smaller than other global estimates. Total NH3 emission was estimated at 11.8 Tg N yr-1. The use of urea and ammonium bicarbonate and the cultivation of rice lead to a high average NH3 loss rate of chemical fertilizer in the region. Emissions were distributed at 0.5° grid by using a global landuse database.

  11. N2O release from agro-biofuel production negates global warming reduction by replacing fossil fuels

    Science.gov (United States)

    Crutzen, P. J.; Mosier, A. R.; Smith, K. A.; Winiwarter, W.

    2008-01-01

    The relationship, on a global basis, between the amount of N fixed by chemical, biological or atmospheric processes entering the terrestrial biosphere, and the total emission of nitrous oxide (N2O), has been re-examined, using known global atmospheric removal rates and concentration growth of N2O as a proxy for overall emissions. For both the pre-industrial period and in recent times, after taking into account the large-scale changes in synthetic N fertiliser production, we find an overall conversion factor of 3-5% from newly fixed N to N2O-N. We assume the same factor to be valid for biofuel production systems. It is covered only in part by the default conversion factor for "direct" emissions from agricultural crop lands (1%) estimated by IPCC (2006), and the default factors for the "indirect" emissions (following volatilization/deposition and leaching/runoff of N: 0.35-0.45%) cited therein. However, as we show in the paper, when additional emissions included in the IPCC methodology, e.g. those from livestock production, are included, the total may not be inconsistent with that given by our "top-down" method. When the extra N2O emission from biofuel production is calculated in "CO2-equivalent" global warming terms, and compared with the quasi-cooling effect of "saving" emissions of fossil fuel derived CO2, the outcome is that the production of commonly used biofuels, such as biodiesel from rapeseed and bioethanol from corn (maize), depending on N fertilizer uptake efficiency by the plants, can contribute as much or more to global warming by N2O emissions than cooling by fossil fuel savings. Crops with less N demand, such as grasses and woody coppice species, have more favourable climate impacts. This analysis only considers the conversion of biomass to biofuel. It does not take into account the use of fossil fuel on the farms and for fertilizer and pesticide production, but it also neglects the production of useful co-products. Both factors partially compensate

  12. Field and laboratory studies of the nitrogen and oxygen isotopic composition of N2O: Corona discharge production, biomass burning, and ocean and "Arctic hot spot" emissions

    Science.gov (United States)

    Boering, K. A.

    2016-12-01

    While inverse modeling studies of atmospheric nitrous oxide (N2O) concentrations have narrowed uncertainties in the magnitudes, geographic distribution, and timing of N2O fluxes to the atmosphere that are needed to understand and to mitigate the rising concentration of this greenhouse gas and ozone depleting substance in the atmosphere, significant uncertainties remain, including accounting for the return of N2O-depleted air from the stratosphere. Measurements of the average and site-specific nitrogen and the oxygen isotopic compositions of N2O can provide an additional means to attribute observed N2O variations to its various sources or stratospheric sink [e.g., Park et al., 2012]. In this presentation, we will highlight recent laboratory work determining the isotopic composition of N2O produced in a corona discharge (the process that produces N2O in thunderstorms), showing it has an isotopic fingerprint that is distinct from that for soil and ocean emissions, for biomass burning, and for the return of air from the stratosphere. Although N2O produced by lightning is only a small fraction of the global annual source of N2O to the atmosphere, the large and unique isotopic signature of corona discharge N2O now characterized completes the array needed to identify the origin, for example, of the unexplained N2O enhancements measured in the tropical and subtropical upper troposphere during the 2009 HIPPO mission [Wofsy 2011]. Such N2O enhancements may also be consistent with inverse modeling studies [e.g., Hirsch et al., 2006; Huang et al., 2008] suggesting tropical N2O source(s) must be larger than expected from bottom-up inventories, so identifying the source of these enhancements is critical. Isotope compositions of N2O in a biomass burning plume in the tropical upper troposphere, from a Southern Ocean ship cruise, and from an Arctic peat circle `hot spot' will also be briefly compared and contrasted with the corona discharge results. Hirsch, A.I., et al., Glob

  13. Application of biochar to soil and N2O emissions: potential effects of blending fast‐pyrolysis biochar with anaerobically digested slurry

    DEFF Research Database (Denmark)

    Bruun, Esben; Müller-Stöver, Dorette Sophie; Ambus, Per

    2011-01-01

    Soil applications of recalcitrant biochar offer the possibility of mitigating climate change effects through long‐term carbon sequestration and potentially also by reducing emissions of the potent greenhouse gas nitrous oxide (N2O). This laboratory study examined the effect of combining a fast......‐pyrolysis biochar at small (1% by mass) and large (3%) concentrations with anaerobically digested slurry on soil N2O and carbon dioxide (CO2) emissions over a period of 55 days. The results showed that fast‐pyrolysis biochar applied on its own increased N2O emissions from soil. However, when biochar was applied...... together with slurry, the larger biochar concentration decreased N2O emissions by 47%, relative to those from the slurry treatment with the smaller biochar concentration. Reduced N2O emissions coincided with enhanced soil microbial activity and immobilization of nitrogen. A combined application of biochar...

  14. Performance and N2O Formation of the Deammonification Process by Suspended Sludge and Biofilm Systems—A Pilot-Scale Study

    Directory of Open Access Journals (Sweden)

    Carmen Leix

    2016-12-01

    Full Text Available A two-stage deammonification pilot plant with two different second-stage reactors, namely a sequencing batch reactor (SBR with suspended sludge and a moving bed biofilm reactor (MBBR with biofilm carriers, was investigated over a 1.5-year period to compare reactor performances. Additionally, dissolved nitrous oxide (N2O was measured to determine the reactors’ N2O formation potential. Although the nitritation performance was moderate (NO2-N/NH4-N effluent ratio of 0.32 ± 0.15 in combination with SBR and 0.25 ± 0.14 with MBBR, nitrogen turnover and degradation rates exceeding 500 g N/(m3∙day and 80%, respectively, were achieved in both second stages, yet requiring additional aeration. The SBR’s average nitrogen removal was 19% higher than the MBBR’s; however, the SBR’s nitrite influent concentration was comparably elevated. Concerning N2O formation, the nitritation reactor exhibited the lowest N2O concentrations, while the buffer tank, interconnecting the first and second stages, exhibited the highest N2O concentrations of all reactors. Given these high concentrations, a transfer of N2O into the second stage was observed, where anoxic phases enabled N2O reduction. Frequent biomass removal and a decreased hydraulic retention time in the buffer tank would likely minimize N2O formation. For the second stage, enabling anoxic periods in the intermittent aeration cycles right after feeding to support N2O reduction and thus minimize the stripping effects or the implementation of a complete anoxic ammonium oxidation will mitigate N2O emissions.

  15. Co-Regulations of Spartina alterniflora Invasion and Exogenous Nitrogen Loading on Soil N2O Efflux in Subtropical Mangrove Mesocosms

    Science.gov (United States)

    Jia, Dai; Qi, Fei; Xu, Xia; Feng, Jianxiang; Wu, Hao; Guo, Jiemin; Lu, Weizhi; Peng, Ronghao; Zhu, Xiaoshan; Luo, Yiqi; Lin, Guanghui

    2016-01-01

    Both plant invasion and nitrogen (N) enrichment should have significant impact on mangrove ecosystems in coastal regions around the world. However, how N2O efflux in mangrove wetlands responds to these environmental changes has not been well studied. Here, we conducted a mesocosm experiment with native mangrove species Kandelia obovata, invasive salt marsh species Spartina alterniflora, and their mixture in a simulated tide rotation system with or without nitrogen addition. In the treatments without N addition, the N2O effluxes were relatively low and there were no significant variations among the three vegetation types. A pulse loading of exogenous ammonium nitrogen increased N2O effluxes from soils but the stimulatory effect gradually diminished over time, suggesting that frequent measurements are necessary to accurately understand the behavior of N-induced response of N2O emissions. With the N addition, the N2O effluxes from the invasive S. alterniflora were lower than that from native K. obovata mesocosms. This result may be attributed to higher growth of S. alterniflora consuming most of the available nitrogen in soils, and thus inhibiting N2O production. We concluded that N loading significantly increased N2O effluxes, while the invasion of S. alterniflora reduced N2O effluxes response to N loading in this simulated mangrove ecosystem. Thus, both plant invasion and excessive N loading can co-regulate soil N2O emissions from mangrove wetlands, which should be considered when projecting future N2O effluxes from this type of coastal wetland. PMID:26727205

  16. Co-Regulations of Spartina alterniflora Invasion and Exogenous Nitrogen Loading on Soil N2O Efflux in Subtropical Mangrove Mesocosms.

    Directory of Open Access Journals (Sweden)

    Dai Jia

    Full Text Available Both plant invasion and nitrogen (N enrichment should have significant impact on mangrove ecosystems in coastal regions around the world. However, how N2O efflux in mangrove wetlands responds to these environmental changes has not been well studied. Here, we conducted a mesocosm experiment with native mangrove species Kandelia obovata, invasive salt marsh species Spartina alterniflora, and their mixture in a simulated tide rotation system with or without nitrogen addition. In the treatments without N addition, the N2O effluxes were relatively low and there were no significant variations among the three vegetation types. A pulse loading of exogenous ammonium nitrogen increased N2O effluxes from soils but the stimulatory effect gradually diminished over time, suggesting that frequent measurements are necessary to accurately understand the behavior of N-induced response of N2O emissions. With the N addition, the N2O effluxes from the invasive S. alterniflora were lower than that from native K. obovata mesocosms. This result may be attributed to higher growth of S. alterniflora consuming most of the available nitrogen in soils, and thus inhibiting N2O production. We concluded that N loading significantly increased N2O effluxes, while the invasion of S. alterniflora reduced N2O effluxes response to N loading in this simulated mangrove ecosystem. Thus, both plant invasion and excessive N loading can co-regulate soil N2O emissions from mangrove wetlands, which should be considered when projecting future N2O effluxes from this type of coastal wetland.

  17. Subsurface watering resulted in reduced soil N2O and CO2 emissions and their global warming potentials than surface watering

    Science.gov (United States)

    Wei, Qi; Xu, Junzeng; Yang, Shihong; Liao, Linxian; Jin, Guangqiu; Li, Yawei; Hameed, Fazli

    2018-01-01

    Water management is an important practice with significant effect on greenhouse gases (GHG) emission from soils. Nitrous oxide (N2O) and carbon dioxide (CO2) emissions and their global warming potentials (GWPs) from subsurface watering soil (SUW) were investigated, with surface watering (SW) as a control. Results indicated that the N2O and CO2 emissions from SUW soils were somewhat different to those from SW soil, with the peak N2O and CO2 fluxes from SUW soil reduced by 28.9% and 19.4%, and appeared 72 h and 168 h later compared with SW. The fluxes of N2O and CO2 from SUW soils were lower than those from SW soil in both pulse and post-pulse periods, and the reduction was significantly (p0.1) lower that from SW soil. Moreover, N2O and CO2 fluxes from both watering treatments increased exponentially with increase of soil water-filled pore space (WFPS) and temperature. Our results suggest that watering soil from subsurface could significantly reduce the integrative greenhouse effect caused by N2O and CO2 and is a promising strategy for soil greenhouse gases (GHGs) mitigation. And the pulse period, contributed most to the reduction in emissions of N2O and CO2 from soils between SW and SUW, should be a key period for mitigating GHGs emissions. Response of N2O and CO2 emissions to soil WFPS and temperature illustrated that moisture was the dominant parameters that triggering GHG pulse emissions (especially for N2O), and temperature had a greater effect on the soil microorganism activity than moisture in drier soil. Avoiding moisture and temperature are appropriate for GHG emission at the same time is essential for GHGs mitigation, because peak N2O and CO2 emission were observed only when moisture and temperature are both appropriate.

  18. Yield-scaled N2O emissions were effectively reduced by biochar amendment of sandy loam soil under maize - wheat rotation in the North China Plain

    Science.gov (United States)

    Niu, Yuhui; Chen, Zengming; Müller, Christoph; Zaman, Monhammad M.; Kim, Donggill; Yu, Hongyan; Ding, Weixin

    2017-12-01

    It is increasingly recognized that the addition of biochar to soil has potential to mitigate climate change and increase soil fertility by enhancing carbon (C) storage. However, the effect of biochar on yield and nitrous oxide (N2O) emissions from upland fields remains unclear. In this study, a one-year field experiment was conducted in an area of calcareous fluvo-aquic soil to assess and quantify the effect of maize straw biochar in reducing N2O loss during 2014-2015 in the North China Plain. Eight treatments were designed as follows: no nitrogen (N) fertilizer (control, CK); biochar application at rates of 3 (B3), 6 (B6) and 12 (B12) t ha-1; chemical fertilizer (NPK) application at 200 kg N ha-1 (F); and fertilizer plus biochar application at rates of 3 (FB3), 6 (FB6) and 12 (FB12) t ha-1. Crop yield, N2O fluxes, soil mineral N concentrations, and soil auxiliary parameters were measured following the application of treatments during each season. During the maize growing season, N2O emission was 0.57 kg N2O-N ha-1 under CK treatment, and increased to 0.88, 0.93 and 1.10 kg N2O-N ha-1 under B3, B6 and B12, respectively. In contrast, N2O emissions were significantly reduced by 31.4-39.9% (P fertilizer and biochar on N2O emissions (P fertilizer regime. Biochar application did not affect maize yield; however, a significant increase in wheat yield of 16.6-25.9% (P fertilization. Nevertheless, a reduction in wheat yield was measured at a biochar rate of 12 t ha-1 with fertilization. Overall, under maize cropping, N2O emissions per unit yield of grain, biomass, grain N and biomass N (yield-scaled N2O emissions) were significantly reduced by 32.4-39.9% under FB compared with F treatment, regardless of the biochar application rate. Biochar did not affect yield-scaled N2O emissions in wheat. Decreased soil bulk density with biochar is suggested to reduce the denitrification potential and N2O emissions; while increased retention capacity of fertilizer N in biochar-added soil

  19. Long Path Quantum Cascade Laser Based Sensor for Environment Sensing/Ambient Detection of CH4 and N2O

    Science.gov (United States)

    Castillo, P. C.; Sydoryk, I.; Gross, B.; Moshary, F.

    2013-12-01

    Methane (CH4) and Nitrous Oxide (N2O) are long-lived greenhouse gases in the atmosphere with significant global warming effects. These gases also are known to be produced in a number of anthropogenic settings such as manure management systems, which releases substantial GHGs and is mandated by the EPA to provide continuous monitoring. In addition, natural gas leaks in urban areas is another source of strong spatially inhomogeneous methane emissions Most open path methods for quantitative detection of trace gases utilize either Fourier Transform Spectrometer (FTIR) or near-IR differential optical absorption spectroscopy (DOAS). Although, FTIR is suitable for ambient air monitoring measurement of more abundant gases such as CO2 and H20 etc., the lack of spectral resolution makes the retrieval of weaker absorbing features such as N20 more difficult. On the other hand, conventional DOAS systems can be large and impractical. As an alternative, we illustrate a robust portable quantum cascade laser (QCL) approach for simultaneous detection of CH4 and N2O. In particular, gas spectra were recorded by ultrafast pulse intensity (thermal) chirp tuning over the 1299 - 1300cm-1 spectral window. Etalon measurements insure stable tuning was obtained. To deal with multiple species, a LSQ spectral fitting approach was used which accounted for both the overlapping trace gases , background water vapor as well as detector drift and calibration. In summary, ambient concentrations of CH4 with and N2O with accuracy < 1% was obtained on the order of 5ms using optical paths of 500 m path length. In addition, unattended long term operation was demonstrated and validations using other sensors when possible were shown to be consistent. The system accuracy is limited by systemic errors, which are still being explored.

  20. Heterogeneous Nitration of Tyrosine by NO­3 and N2O5: Rates, Mechanisms and Product Yields

    Science.gov (United States)

    Talukdar, R. K.; Witkowski, B.; Burkholder, J. B.; Roberts, J. M.

    2015-12-01

    Nitration of protein-bound tyrosine has been identified as a casual connection between air pollution and human health. Tyrosine is a common amino acid, 4-hydroxyphenylalanine, HO-C6H4-CH2-CH(NH2)-C(O)OH), and is present in many atmospheric bio-aerosols. Nitration of the aromatic units of protein molecules in polluted air enhances their allergenicity. The mechanism of heterogeneous nitration process of bio-aerosols by common nitrating agents in the atmosphere, O3/NO2, NO3, N2O5 is not well understood. This chemistry is thought to proceed via reactions with O3 and NO2 on particle surfaces, through mechanisms that are still uncertain. The possible role of higher nitrogen oxides also remains uncertain, partly due to a lack of measurements of fundamental chemical and physical parameters. In this work, we undertook measurements of reactive uptake of NO3, N2O5, as a function of relative humidity and temperature in a tyrosine coated flow tube reactor with chemical ionization mass spectrometric (CIMS) detection. Uptake coefficients on tyrosine coated flow tube were small under low relative humidity but were enhanced by an order of magnitude in the presence of high relative humidity, particularly for N2O5. The measured uptake coefficients were mostly due to reaction with water adsorbed on the surface of the flow tube. Only ~10% of the reactive uptake could be attributed to reaction with tyrosine. Following uptake, the contents of the flow tube were extracted, and analyzed using electrospray ionization - mass spectrometer (ESI-MS) to identify and quantify the products of the nitration reaction. The only organic reaction product detected was 3-nitro-tyrosine (3-NT). The measured uptake coefficients, mechanism of the title reactions and the possible atmospheric implications of these findings will be discussed.

  1. A new six-dimensional potential energy surface for H2-N2O and its adiabatic-hindered-rotor treatment

    Science.gov (United States)

    Wang, Lecheng; Xie, Daiqian; Le Roy, Robert J.; Roy, Pierre-Nicholas

    2013-07-01

    A six-dimensional ab initio potential energy surface (PES) for H2-N2O which explicitly includes the symmetric and asymmetric vibrational coordinates Q1 and Q3 of N2O is calculated at the coupled-cluster singles and doubles with noniterative inclusion of connected triple level using an augmented correlation-consistent polarized-valence quadruple-zeta basis set together with midpoint bond functions. Four-dimensional intermolecular PESs are then obtained by fitting the vibrationally averaged interactions energies for υ3(N2O) = 0 and 1 to the Morse/long-range analytical form. In the fits, fixing the long-range parameters at theoretical values smoothes over the numerical noise in the ab initio points in the long-range region of the potential. Using the adiabatic hindered-rotor approximation, two-dimensional PESs for hydrogen-N2O complexes with different isotopomers of hydrogen are generated by averaging the 4D PES over the rotation of the hydrogen molecule within the complex. The band-origin shifts for the hydrogen-N2O dimers calculated using both the 4D PESs and the angle-averaged 2D PESs are all in good agreement with each other and with the available experimental observations. The predicted infrared transition frequencies for para-H2-N2O and ortho-D2-N2O are also consistent with the observed spectra.

  2. Coupled effects of straw and nitrogen management on N2O and CH4 emissions of rainfed agriculture in Northwest China

    Science.gov (United States)

    Htun, Yin Min; Tong, Yanan; Gao, Pengcheng; Xiaotang, Ju

    2017-05-01

    Straw incorporation is a common agricultural practice, but the additional carbon source may increase greenhouse gas emissions by stimulating microbial activity in soil, particularly when straw is applied at the same time as nitrogen (N) fertilizer. We investigated the coupled effects of straw and N fertilizer on greenhouse gas emissions in a rainfed winter wheat-summer fallow system in Northwest China. Simultaneous applications of straw and N fertilizer increased N2O emissions by up to 88%, net greenhouse gas (NGHG) emission and net greenhouse gas intensity (NGHGI) by over 90%, and the N2O emission factor by over 2-fold. When straw was applied before N fertilizer, the emission factor (0.22%) decreased by approximately one-half compared with that for simultaneous applications (0.45%). In addition, early straw incorporation decreased N2O emissions, NGHG, and NGHGI by 35% (0.62 kg N2O-N ha-1 yr-1), 40% (242 kg CO2-eq ha-1 yr-1), and 38% (42 kg CO2-eq t-1 grain), respectively. We identified the period 30-35 days after N fertilization as a crucial period for evaluating the effectiveness of management practices on N2O emissions. The time between straw and fertilizer applications was negatively related to N2O emission (R2 = 0.8031; p early straw incorporation can effectively mitigate greenhouse gas emissions by reducing N2O flux and increasing soil CH4 uptake without significantly decreasing grain yield.

  3. Effects of soil temperature, flooding, and organic matter addition on N2O emissions from a soil of Hongze Lake wetland, China.

    Science.gov (United States)

    Lu, Yan; Xu, Hongwen

    2014-01-01

    The objectives of this study were to test the effects of soil temperature, flooding, and raw organic matter input on N2O emissions in a soil sampled at Hongze Lake wetland, Jiangsu Province, China. The treatments studied were-peat soil (I), peat soil under flooding (II), peat soil plus raw organic matter (III), and peat soil under flooding plus organic matter. These four treatments were incubated at 20°C and 35°C. The result showed that temperature increase could enhance N2O emissions rate and cumulative emissions significantly; moreover, the flooded soil with external organic matter inputs showed the lowest cumulative rise in N2O emissions due to temperature increment. Flooding might inhibit soil N2O emissions, and the inhibition was more pronounced after organic matter addition to the original soil. Conversely, organic matter input explained lower cumulative N2O emissions under flooding. Our results suggest that complex interactions between flooding and other environmental factors might appear in soil N2O emissions. Further studies are needed to understand potential synergies or antagonisms between environmental factors that control N2O emissions in wetland soils.

  4. Characterization of catalytic supports based in mixed oxides for control reactions of NO and N2O

    International Nuclear Information System (INIS)

    Garcia C, M.A.; Perez H, R.; Gomez C, A.; Diaz, G.

    1999-01-01

    The catalytic supports Al 2 O 3 , La 2 O 3 and Al 2 O 3 -La 2 O 3 were prepared by the Precipitation and Coprecipitation techniques. The catalytic supports Al 2 O 3 , La 2 O 3 and Al 2 O 3 -La 2 O 3 were characterized by several techniques to determine: texture (Bet), crystallinity (XRD), chemical composition (Sem)(Ftir) and it was evaluated their total acidity by reaction with 2-propanol. The investigation will be continued with the cobalt addition and this will be evaluated for its catalytic activity in control reactions of N O and N 2 O. (Author)

  5. Optimización de procesos biológicos para la eliminación de N2O

    OpenAIRE

    Arvelo Yagua, Ilan Alexander

    2014-01-01

    El N2O es uno de los principales gases de efecto invernadero, ocupando el tercer lugar de las emisiones globales medidas en toneladas de CO2 equivalente, siendo la principal fuente antropogénica el uso de fertilizantes nitrogenados. Actualmente la tecnología para su tratamiento por mecanismos biológicos presenta escasos avances, y debido a ello surge la necesidad de la investigación experimental para el conocimiento de parámetros operacionales y de diseño que permitan el uso óptimo de reac...

  6. Flux des gaz à effet de serre (CH 4 et N 2 O) dans le fleuve Niger en ...

    African Journals Online (AJOL)

    Les écosystèmes aquatiques constituent une source importante d'émission des gaz à effet de serre très souvent négligés dans l'établissement des bilans globaux dont les principaux gaz sont le CO2 le CH4 et le N2O. L'objectif de cette étude est de déterminer l'origine des flux des deux derniers gaz et la capacité ...

  7. Linking N2O emissions from biochar-amended soil to the structure and function of the N-cycling microbial community

    Science.gov (United States)

    Harter, Johannes; Krause, Hans-Martin; Schuettler, Stefanie; Ruser, Reiner; Fromme, Markus; Scholten, Thomas; Kappler, Andreas; Behrens, Sebastian

    2014-01-01

    Nitrous oxide (N2O) contributes 8% to global greenhouse gas emissions. Agricultural sources represent about 60% of anthropogenic N2O emissions. Most agricultural N2O emissions are due to increased fertilizer application. A considerable fraction of nitrogen fertilizers are converted to N2O by microbiological processes (that is, nitrification and denitrification). Soil amended with biochar (charcoal created by pyrolysis of biomass) has been demonstrated to increase crop yield, improve soil quality and affect greenhouse gas emissions, for example, reduce N2O emissions. Despite several studies on variations in the general microbial community structure due to soil biochar amendment, hitherto the specific role of the nitrogen cycling microbial community in mitigating soil N2O emissions has not been subject of systematic investigation. We performed a microcosm study with a water-saturated soil amended with different amounts (0%, 2% and 10% (w/w)) of high-temperature biochar. By quantifying the abundance and activity of functional marker genes of microbial nitrogen fixation (nifH), nitrification (amoA) and denitrification (nirK, nirS and nosZ) using quantitative PCR we found that biochar addition enhanced microbial nitrous oxide reduction and increased the abundance of microorganisms capable of N2-fixation. Soil biochar amendment increased the relative gene and transcript copy numbers of the nosZ-encoded bacterial N2O reductase, suggesting a mechanistic link to the observed reduction in N2O emissions. Our findings contribute to a better understanding of the impact of biochar on the nitrogen cycling microbial community and the consequences of soil biochar amendment for microbial nitrogen transformation processes and N2O emissions from soil. PMID:24067258

  8. N2O production pathway change during drought and following wet-up in a controlled rainforest at Biosphere 2 Center

    Science.gov (United States)

    van Haren, J.; Yamagishi, H.; Yoshida, N.

    2003-12-01

    N2O is the fourth most important greenhouse gas and it leads to ozone destruction in the stratosphere. Rainforests account for ˜ 20% of global N2O emissions. In soils N2O can be produced though hydroxylamine oxidation by methanotrophs, nitrification, nitrifier denitrification, and denitrification. The former two processes occur under aerobic and the latter two under anaerobic conditions. During a drought, soils are expected to change from more anaerobic to more aerobic conditions, thus leading to a change in N2O production pathway. To test this we conducted a 37-day drought in a controlled rainforest mesocosm at Biosphere 2 Center. Three times during the drought and immediately after wet-up, we collected air and soil samples to determine the N2O isotope changes. Top 10 cm soil Water Filled Pore Space (WFPS) decreased from ˜ 60 to 20% and WFPS below 50 cm decreased from ˜ 50 to 40% during the drought. Meanwhile the whole system N2O flux decreased from 120+/-4 to 41.5+/-2.6 μ g-N/m2/hr. δ 15N, δ 18O, and site preference of N2O increased by 7, ˜2, and ˜2.5‰ , respectively. Immediately following wet-up a pulse of N2O was released with δ 15N, δ 18O, and Site preference 15, 3 and 15‰ lower than before. We will present evidence to support that the stable isotope increase with soil water loss can be explained by an increase in contribution of hydroxylamine oxidation by methanotrophs. Whereas the isotopic change following wet-up is due to increased contribution from nitrifier-denitrification to the overall N2O flux.

  9. Simulating N2O emissions from irrigated cotton wheat rotations in Australia using DAYCENT: Mitigation options by optimized fertilizer and irrigation management

    Science.gov (United States)

    Scheer, Clemens; DelGrosso, Stephen; Parton, William; Rowlings, David; Grace, Peter

    2014-05-01

    Irrigation and fertilization do not only stimulate plant growth, but also accelerate microbial C- and N-turnover in the soil and thus can lead to enhanced emissions of nitrous oxide (N2O) from soils. In Australia there are more than 2 million hectares of agricultural land under irrigation and research has now focused on a combination of nitrogen fertilizer and irrigation management to maintain crop yields, maximize nitrogen use efficiency and reduce N2O emissions. Process-based models are now being used to estimate N2O emissions and assess mitigation options of N2O fluxes by improving management at field, regional and national scales. To insure that model predictions are reliable it is important to rigorously test the model so that uncertainty bounds for N2O emissions can be reduced and the impacts of different management practices on emissions can be better quantified. We used high temporal frequency dataset of N2O emissions to validate the performance of the agroecosystem model DayCent to simulate daily N2O emissions from sub-tropical vertisols under different irrigation intensities. Furthermore, we evaluated potential N2O mitigation strategies in irrigated cotton-wheat rotations in Australia by simulating different fertilizer and irrigation management scenarios over a climatically variable 25 year time span. DayCent accurately predicted soil moisture dynamics and the timing and magnitude of high fluxes associated with fertilizer additions and irrigation events. At the daily scale we found a good correlation of predicted vs. measured N2O fluxes (r2 = 0.52), confirming that DayCent can be used to test agricultural practices for mitigating N2O emission from irrigated cropping systems. The simulations of different fertilization and irrigation practices in cotton-wheat rotations over a 25 year time frame clearly showed that there is scope for reducing N2O emissions by modified fertilizer and irrigation management. For wheat and for cotton the model predicted that a

  10. Characteristics and kinetics of ammonia and N2O emissions of aged refuse irrigated from landfill leachate.

    Science.gov (United States)

    Gao, Jixi; Zhang, Houhu; Cao, Xuezhang; Ding, Jian; Yu, Guanghui; Xu, Huacheng

    2013-05-01

    This is the first attempt to report the gaseous nitrogen emissions from landfill leachate filtration methods by irrigating the aged refuse. A first-order reaction model was a good fit for the increase in ammonia emissions from aged refuse, clay and sandy soil incubated for 120 h after adding the leachate-N solution. The emissions of ammonia and N2O by the three experimental materials fit well to first-order and zero-order models, respectively. The maximum ammonia emission from aged refuse was approximately 1.17 mg NH4(+)-Nkg(-1) d.w. and the calculated emission factor was 1.95‰, which was 3.76 and 2.67 times lower than that of sandy and clay soils, respectively. The tendencies of NH4(+)-N nitrification and NO3(-)-N generations fit well to the zero-order reaction model and the net nitrification rate by the aged refuse was 1.30 (pammonia. The emission factor for N