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Sample records for ch4 ja n2o

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

    Directory of Open Access Journals (Sweden)

    J. Laubach

    2015-09-01

    Full Text Available 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 spectrometer (FTIR, measuring 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 60 % of days at one site and 77 % at the other. Both methods indicated both sites as net sources of CH4 and N2O. Mean emission rates for one year at the unfertilised, winter-grazed site were 8.2 (± 0.91 nmol CH4 m−2 s−1 and 0.40 (± 0.018 nmol N2O m−2 s−1. During the same year, mean emission rates at the irrigated, fertilised and rotationally-grazed site were 7.0 (± 0.89 nmol CH4 m−2 s−1 and 0.57 (± 0.019 nmol N2O m−2 s−1. At this site, the N2O emissions amounted to 1

  2. 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

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

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    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

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

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    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 (N2O), nitric oxide (NO) and methane (CH4). 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 N2O, NO and CH4 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 N2O emissions. The fluxes of NO and CH4 differed between forest edge and interior, but not for N2O. 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 CH4 (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 CH4 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.

  5. Effect of Biogas Digested Liquid on CH4 and N2O Flux in Paddy Ecosystem

    Institute of Scientific and Technical Information of China (English)

    Ankit Singla; Kazuyuki Inubushi

    2014-01-01

    Biogas production generates digested slurry as a byproduct. It can be used as a fertilizer especially after its conversion into digested liquid. A pot based study was conducted in order to evaluate the effect of the application of digested liquid on CH4 and N2O lfux, and plant biomass in paddy. Analysis revealed that digested liquid treated soils released more CH4 compared to ammonium sulphate and the control. Ammonium sulphate treated soil emitted the highest N2O whereas digested liquid application decreased its emission signiifcantly. Further, the cumulative emission over 101 d of the experiment was found to be higher for CH4 (16.9 to 29.9 g m-2) compared to N2O (-49.3 to 18.9 mg m-2) for all treatments. Digested liquid application had positive impact on plant variables such as panicle number and weight of panicles. This study suggests that digested liquid application signiifcantly decrease N2O emission and increase CH4 emission possibly due to affecting the availability of organic C in the soil to microbial activity for methanogenesis. Another possibility for enhancing CH4 emission by following biogas digested liquid could be attributed to the increase in plant biomass.

  6. Seasonal variability of CH4 and N2O fluxes over a managed temperate mountain grassland

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    Hoertnagl, Lukas; Wohlfahrt, Georg

    2013-04-01

    The quantification of greenhouse gas (GHG) budgets on a global scale is an important step in assessing the effect of anthropogenic and biogenic controls on a future climate. In the past, measurements of CO2 fluxes were conducted over a wide array of ecosystems, leading to a better understanding of its exchange patterns on different time scales and more sophisticated models. However, only few studies quantified the fluxes of the other two major GHG, methane (CH4) and nitrous oxide (N2O), mainly due to expensive sensors and their time-consuming maintenance. In addition, early CH4 and N2O measurements mainly focused on ecosystems with presumably high emissions of CH4 (e.g. wetlands) or N2O (e.g. heavily fertilized crops). In recent years, devices for CH4 and N2O measurements became widely available and more studies are conducted over sites that exert small and often close-to-zero fluxes. Despite recent advances in sensor sensitivity and stability, the quantification of CH4 and N2O exchange rates remains challenging. Here we present measurements of CH4 and N2O exchange rates of a temperate mountain grassland managed as a hay meadow near the village Neustift in the Stubai Valley, Austria, that started in April 2010 by means of the eddy covariance method. The three wind components and the speed of sound were acquired at a time resolution of 20 Hz, while CH4 and N2O mixing ratios were recorded at 2 Hz by a quantum cascade laser absorption spectrometer (QCL-AS). Fluxes of both compounds were calculated using the virtual disjunct eddy covariance method (vDEC). For better comparability fluxes of N2O and CH4 were also converted to g CO2-equivalents and compared to the CO2 exchange at the same site. In addition to exchange rates, challenges regarding the calculation of GHG fluxes at the investigated grassland site will also be discussed. In 2011, deposition of CH4 was recorded on 9 days with average uptake rates of -0.6 nmol m-2 s-1. Peak emissions of up to 12.9 nmol m-2 s-1

  7. Harmonisation and diagnostics of MIPAS ESA CH4 and N2O profiles using data assimilation

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    Errera, Quentin; Ceccherini, Simone; Christophe, Yves; Chabrillat, Simon; Hegglin, Michaela I.; Lambert, Alyn; Ménard, Richard; Raspollini, Piera; Skachko, Sergey; van Weele, Michiel; Walker, Kaley A.

    2016-12-01

    This paper discusses assimilation experiments of methane (CH4) and nitrous oxide (N2O) profiles retrieved from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). Here we focus on data versions 6 and 7 provided by the ESA processor. These data sets have been assimilated by the Belgian Assimilation System for Chemical ObsErvations (BASCOE). The CH4 and N2O retrieved profiles can oscillate, especially in the tropical lower stratosphere. Using the averaging kernels of the observations and a background error covariance matrix, which has previously been calibrated, allows the system to partly remedy this issue and provide assimilated fields that are more regular vertically. In general, there is a good agreement between the BASCOE analyses and independent observations from ACE-FTS (CH4 and N2O) and MLS (N2O), demonstrating the general good quality of CH4 and N2O retrievals provided by MIPAS ESA. Nevertheless, this study also identifies two issues in these data sets. First, time series of the observations show unexpected discontinuities due to an abrupt change in the gain of MIPAS band B, generally occurring after the instrument decontamination. Since the calibration is performed weekly, the abrupt change in the gain affects the measurements until the subsequent calibration is performed. Second, the correlations between BASCOE analyses and independent observations are poor in the lower stratosphere, especially in the tropics, probably due to the presence of outliers in the assimilated data. In this region, we recommend using MIPAS CH4 and N2O retrievals with caution.

  8. Relationship between CH4 and N2O emissions from rice field and its impacting factors

    Institute of Scientific and Technical Information of China (English)

    HOUAixin; CHENGuanxiong; WUJie; WANGZhengping

    1998-01-01

    To find out the relationship between CH4 and N2O emissions from rice field and determine the key factors affecting the emissions, and give a scientifie basis for working out mitigation options of their emissions from flooded rice field, we measured the emissions and their impacting environmental factors systematically and simultaneously from Mar to Dee in 1995-1996 in northern China.

  9. Climate relevant trace gases (N2O and CH4) in the Eurasian Basin (Arctic Ocean)

    Science.gov (United States)

    Verdugo, Josefa; Damm, Ellen; Snoeijs, Pauline; Díez, Beatriz; Farías, Laura

    2016-11-01

    The concentration of greenhouse gases, including nitrous oxide (N2O), methane (CH4), and compounds such as total dimethylsulfoniopropionate (DMSPt), along with other oceanographic variables were measured in the ice-covered Arctic Ocean within the Eurasian Basin (EAB). The EAB is affected by the perennial ice-pack and has seasonal microalgal blooms, which in turn may stimulate microbes involved in trace gas cycling. Data collection was carried out on board the LOMROG III cruise during the boreal summer of 2012. Water samples were collected from the surface to the bottom layer (reaching 4300 m depth) along a South-North transect (SNT), from 82.19°N, 8.75°E to 89.26°N, 58.84°W, crossing the EAB through the Nansen and Amundsen Basins. The Polar Mixed Layer and halocline waters along the SNT showed a heterogeneous distribution of N2O, CH4 and DMSPt, fluctuating between 42-111 and 27-649% saturation for N2O and CH4, respectively; and from 3.5 to 58.9 nmol L-1 for DMSPt. Spatial patterns revealed that while CH4 and DMSPt peaked in the Nansen Basin, N2O was higher in the Amundsen Basin. In the Atlantic Intermediate Water and Arctic Deep Water N2O and CH4 distributions were also heterogeneous with saturations between 52% and 106% and 28% and 340%, respectively. Remarkably, the Amundsen Basin contained less CH4 than the Nansen Basin and while both basins were mostly under-saturated in N2O. We propose that part of the CH4 and N2O may be microbiologically consumed via methanotrophy, denitrification, or even diazotrophy, as intermediate and deep waters move throughout EAB associated with the overturning water mass circulation. This study contributes to baseline information on gas distribution in a region that is increasingly subject to rapid environmental changes, and that has an important role on global ocean circulation and climate regulation.

  10. Nitrate loading and CH4 and N2O Flux from headwater streams

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    Schade, J. D.; Bailio, J.; McDowell, W. H.

    2015-12-01

    Freshwater ecosystems transport and process significant amounts of terrestrial carbon and can be considerable sources of CO2, CH4, and N2O. A great deal of uncertainty, however, remains in both global estimates and our understanding of drivers of freshwater greenhouse gas emissions. Furthermore, small headwater streams have received insufficient attention to date and may contribute disproportionately to global GHG flux. Our objective was to quantify GHG flux and assess the impact of changes in DOC and NO3 concentrations in surface and subsurface water on flux rates in three streams in the Lamprey River watershed in New Hampshire, USA, that contrast in surface water DOC:NO3. We measured DOC, NO3 and dissolved gas concentrations in surface waters of each stream monthly from May 2011 to April 2012. Empirical measurements of reaeration coefficients were used to convert dissolved gas concentrations to fluxes. We found higher GHG concentrations and fluxes in the two streams with high DOC concentrations, particularly gases produced by anaerobic metabolism (CH4, N2O from methanogenesis and denitrification, respectively). The stream with high DOC and high NO3 showed high N2O and low CH4 flux, while the high DOC, low NO3 stream showed high CH4 and low N2O flux. Our results are consistent with a model in which C inputs drive total GHG production, while NO3 input regulates the relative importance of CH4 and N2O by suppressing methanogenesis and stimulating denitrification. The magnitude of GHG fluxes suggests that streams in this region are likely to be small sources of CO2, but potentially important sources of CH4 and N2O. Since CH4 and N2O are many times more powerful than CO2 at trapping heat in the atmosphere, freshwater emissions of these gases have the potential to offset a significant proportion of the climate benefits of the terrestrial carbon sink, a possibility that has not been sufficiently incorporated into climate models.

  11. 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

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

    Science.gov (United States)

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

    2010-07-01

    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 exception of

  13. Preliminary studies on microbiological mechanism of the dynamics of CH4 and N2O emission from rice field

    Institute of Scientific and Technical Information of China (English)

    HOUAixin; CHENGuanxiong; WUjie; WANGZhengping

    1998-01-01

    Greenhouse gases, CH4 and N2O emitted from rice field, are the products of microbial metabolism. So the characteristics of CH4 and N2O production and emission in rice field can be understood through microbiological study. In this paper, the relationships between the dynamics of CH4 and N2O emission from rice field in northern China and the related soil bacteria groups were discussed.

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

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    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.

  15. Winter greenhouse gas fluxes (CO2, CH4 and N2O from a subalpine grassland

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    L. Merbold

    2013-05-01

    Full Text Available Although greenhouse gas emissions during winter contribute significantly to annual balances, their quantification is still highly uncertain in snow-covered ecosystems. Here, carbon dioxide (CO2, methane (CH4 and nitrous oxide (N2O fluxes were measured at a subalpine managed grassland in Switzerland using concentration gradients within the snowpack (CO2, CH4, N2O and the eddy covariance method (CO2 during the winter 2010/2011. Our objectives were (1 to identify the temporal and spatial variation of greenhouse gases (GHGs and their drivers, and (2 to estimate the GHG budget of the site during this specific season (1 December–31 March, 121 days. Mean winter fluxes (December–March based on the gradient method were 0.77 ± 0.54 μmol m−2 s−1 for CO2 (1.19 ± 1.05 μmol m−2 s−1 measured by eddy covariance, −0.14 ± 0.09 nmol m−2 s−1 for CH4 and 0.23 ± 0.23 nmol m−2 s−1 for N2O, respectively. In comparison with the CO2 fluxes measured by eddy covariance, the gradient technique underestimated the effluxes by 50%. While CO2 and CH4 fluxes decreased with the progressing winter season, N2O fluxes did not follow a seasonal pattern. The major variables correlating with the fluxes of CO2 and CH4 were soil temperature and snow water equivalent, which is based on snow height and snow density. N2O fluxes were only explained poorly by any of the measured environmental variables. Spatial variability across the valley floor was smallest for CO2 and largest for N2O. During the winter season 2010/2011, greenhouse gas fluxes ranged between 550 ± 540 g CO2 m−2 estimated by the eddy covariance approach and 543 ± 247 g CO2 m−2, −0.4 ± 0.01 g CH4 m−2 and 0.11 ± 0.1 g N2O m−2 derived by the gradient technique. Total seasonal greenhouse gas emissions from the grassland were between 574 ± 276 and 581 ± 569 g CO2 eq. m−2, with N2O contributing 5% to the overall budget and CH4 reducing the budget by 0.1%. Cumulative budgets of CO2 were

  16. 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

  17. Coastal hypoxia/anoxia as a source of CH4 and N2O

    Directory of Open Access Journals (Sweden)

    M. I. Scranton

    2009-10-01

    Full Text Available We review here available information on distributions of methane (CH4 and nitrous oxide (N2O from major, mostly coastal, oxygen (O2-deficient zones produced due to both natural processes and human activities (mainly eutrophication. Concentrations of both gases in subsurface waters are affected by ambient O2 levels. In the case of CH4, bottom-water O2 content probably affects emission from sediments, believed to be the main source of water-column CH4, as well as its oxidative loss in water itself. Highest CH4 accumulation (several μM occurs in silled basins having anoxic deep waters such as the Black Sea and the Cariaco Basin. One to two orders of magnitude smaller, but still significant, accumulation also occurs in bottom waters of open margins experiencing anoxia and in silled basins containing suboxic/severely hypoxic waters. In highly eutrophic waters over open continental shelves (such as the upwelling zone off Namibia and the "dead zone" in the Gulf of Mexico high CH4 concentrations (several hundred nM may occur in non-sulphidic waters as well, but in these regions it is difficult to differentiate the hypoxia-induced enhancement from in situ production of CH4 in the water column and, sometimes, large inputs of CH4 associated with freshwater runoff or seepage from sediments. Despite the observed CH4 build-up in low-O2 bottom waters, methanotrophic activity severely restricts its emission from the ocean. As a result, an intensification or expansion of coastal hypoxic 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 severely hypoxic 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 exception of semi

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

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    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

  19. An improved gas chromatography for rapid measurement of CO2,CH4 and N2O

    Institute of Scientific and Technical Information of China (English)

    WANG Ying-hong; WANG Yue-si; SUN Yang; XU Zhong-jun; LIU Guang-ren

    2006-01-01

    Combining improved injector, gas line and valve-driving modules, a GC equipped with FID and ECD, could simultaneously measure CH4, CO2 and N2O in an air sample within 4 min. Test results showed that the system has high sensitivity, resolution and precision; the linear response range of the system meets the requirement of in situ flux measurements. Thus, the system is suitable for monitoring fluxes of main greenhouse gases in terrestrial ecosystem since it is easy to use, efficacious, stable and reliable to collect data.

  20. 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.

  1. Effects of soil moisture and temperature on CH4 oxidation and N2O emission of forest soil

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Soil samples were taken from depth of 0-12 cm in the virgin broad- leaved/Korean pine mixed forest in Changbai Mountain in April, 2000. 20 μL.L-1 and 200 μL.L-1 CH4 and N2O concentration were supplied for analysis. Laboratory study on CH4 oxidation and N2O emission in forest soil showed that fresh soil sample could oxidize atmospheric methane and product N2O. Air-dried soil sample could not oxidize atmospheric methane, but could product N2O. However, it could oxidize the supplied methane quickly when its concentration was higher than 20 μL.L-1. The oxidation rate of methane was increased with its initial concentration. An addition of water to dry soil caused large pulse of N2O emissions within 2 hours. There were curvilinear correlations between N2O emission and temperature (r2 =0.706, p <0.05), and between N2O emission and water content (r2 =0.2968, p <0.05). These suggested temperature and water content were important factors controlling N2O emission. The correlation between CH4 oxidization and temperature was also found while CH4 was supplied 200 μL. L-1 (r2 =0.3573, p <0.05). Temperature was an important factor controlling CH4 oxidation. However, when 20 μL. L-1 CH4 was supplied, there was no correlation among CH4 oxidization, N2O emission, temperature and water content.

  2. Annual balances of CH4 and N2O from a managed fen meadow using eddy covariance flux measurements

    NARCIS (Netherlands)

    Kroon, P.S.; Schrier-Uijl, A.P.; Hensen, A.; Veenendaal, E.M.; Jonker, H.J.J.

    2010-01-01

    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 ach

  3. [An investigation of the CH4 and N2O emission factors of light-duty gasoline vehicles].

    Science.gov (United States)

    He, Li-qiang; Song, Jing-hao; Hu, Jing-nan; Xie, Shu-xia; Zu, Lei

    2014-12-01

    In China, most of the studies of vehicular greenhouse gas (GHG) emissions have been focused on CO2 emissions. The investigation of non-CO2 GHGs, e.g. CH4 and N2O, are mainly carried out based on models developed in Europe and the US, and there are few vehicle emission tests for CH4 and N2O. In this study, 22 light-duty gasoline vehicles (LDGVs) were selected for tailpipe CH4 and N2O tests using chassis dynamometer, and their emission factors were obtained based on the NEDC driving cycle. The results showed that the CH4 emission factors of China I to China IV LDGVs were 0.048 g x km(-1), 0.048 g x km(-1), 0.038 g x km(-1) and 0.028 g x km(-1), respectively. For N2O, the emission factors of China I to China IV were 0.045 g x km(-1), 0.039 g x km(-1), 0.026 g x km(-1) and 0.021 g x km(-1), respectively. In the GHGs emissions (in terms of CO2 Eq.) per LDGV, the percentage of CH4 and N2O emissions decreased gradually with tightening of emission standards. The contribution of CH4 emissions was lower than 0.5% in the total emissions, and N2O share rate was between 3.03% and 6.35%. Therefore, tightening emission standards can effectively reduce the CH4 and N2O emissions, to mitigate the greenhouse effects caused by vehicle emissions.

  4. Fluxes of CH4 and N2O from soil under a tropical seasonal rain forest in Xishuangbanna, Southwest China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    CH4 and N2O fluxes from soil under a tropical seasonal rain forest in Xishuangbanna, Southwest China were measured for one year using closed static chamber technique and gas chromatography method. Three treatments were set in the studied field: (A) litter-free,(B) with litter, and (C) with litter and seedling. The results showed that the soil in our study was a sink of atmospheric CH4 and source of atmospheric N2O. The observed mean CH4 fluxes from treatments A, B, and C were -50.0±4.0, -35.9±2.8,-31.6±2.8 μgC/(m2·h),respectively,and calculated annual fluxes in2003 were -4.1,-3.1,and -2.9kgC/hm2,respectively.The observed mean N2O fluxes from treatments A,B,and C were 30.9±3.1,28.2±3.5,50.2±3.7μgN/(m2·h),respectively,and calculated annual fluxes in 2003 were 2.8, 2.6, and 3.7 kgN/hm2, respectively. Seasonal variations in CH4 and N2O fluxes were significant among all the three treatments. The presence of litter decreased CH4 uptake during wet season (P < 0.05), but not during dry season. There was a similar increase in seedlings-mediated N2O emissions during wet and dry seasons, indicating that seedlings increased N2O emission in both seasons. A strong positive relationship existed between CH4 fluxes and soil moisture for all the three treatments, and weak relationship between CH4 fluxes and soil temperature for treatment B and treatment C. The N2O fluxes correlated with soil temperature for all the three treatments.

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

    Directory of Open Access Journals (Sweden)

    P. Bergamaschi

    2014-06-01

    Full Text Available European CH4 and N2O emissions are estimated for 2006 and 2007 using four independent 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 emissions, which is particularly important for verifying bottom-up emission inventories. We use continuous observations from 10 European stations (including five tall towers for CH4 and 9 continuous stations for N2O, complemented by additional European and global flask sampling sites. The available observations mainly constrain CH4 and N2O emissions from north-western and eastern Europe. The inversions are strongly driven by the observations and the derived total emissions of larger countries show little dependence on the emission inventories used a priori. Three inverse models yield 26–56% higher total CH4 emissions from north-western and eastern Europe compared to bottom-up emissions reported to the UNFCCC, while one model is close to the UNFCCC values. In contrast, the inverse modelling estimates of European N2O emissions are in general close to the UNFCCC values, with the overall range from all models being much smaller than the UNFCCC uncertainty range for most countries. Our analysis suggests that the reported uncertainties for CH4 emissions might be underestimated, while those for N2O emissions are likely overestimated.

  6. N 2O emissions at municipal solid waste landfill sites: Effects of CH 4 emissions and cover soil

    Science.gov (United States)

    Zhang, Houhu; He, Pinjing; Shao, Liming

    Municipal solid waste landfills are the significant anthropogenic sources of N 2O due to the cooxidation of ammonia by methane-oxidizing bacteria in cover soils. Such bacteria could be developed through CH 4 fumigation, as evidenced by both laboratory incubation and field measurement. During a 10-day incubation with leachate addition, the average N 2O fluxes in the soil samples, collected from the three selected landfill covers, were multiplied by 1.75 ( p landfill sites, N 2O fluxes in two landfill sites were significantly correlated with the variations of the CH 4 emissions without landfill gas recovery ( p landfill gas recovery in another landfill site ( p > 0.05). The annual average N 2O flux was 176 ± 566 μg N 2O-N m -2 h -1 ( p landfill site, which was 72% ( p landfill sites, respectively. The magnitude order of N 2O emissions in three landfill sites was also coincident by the results of laboratory incubation, suggesting the sandy soil cover could mitigate landfill N 2O emissions.

  7. Winter greenhouse gas emissions (CO2, CH4 and N2O from a sub-alpine grassland

    Directory of Open Access Journals (Sweden)

    F. Hagedorn

    2013-01-01

    Full Text Available Carbon dioxide (CO2, methane (CH4 and nitrous oxide (N2O fluxes were measured during the winter 2010/2011 at a~sub-alpine managed grassland in Switzerland using concentration gradients within the snowpack (CO2, CH4, N2O and the eddy covariance method (CO2. Measured snow densities were used to calculate the respective greenhouse gas (GHG fluxes. Mean winter fluxes based on the gradient method were 0.74 ± 0.53 μmol m−2 s−1 for CO2, −0.14 ± 0.09 nmol m−2 s−1 for CH4 and 0.23 ± 0.23 nmol m−2 s−1 for N2O, respectively. While CO2 and CH4 fluxes decreased with progressing winter season N2O fluxes did not follow a~seasonal pattern. Key variables driving the fluxes of CO2 and CH4 were soil surface temperatures and snow-water equivalent. N2O fluxes were only poorly explained by any of the measured factors in the soil and snow. Spatial variability across the valley floor was smallest for CO2 and largest for N2O. During the winter season 2010/2011 (November–April greenhouse gas fluxes accumulated to 631–670 g CO2 m−2, −0.04 g CH4 m−2 and 0.13 g N2O m−2. Total greenhouse gas emissions from the grassland were between 669–709 g CO2 eq. m−2, with N2O contributing 5% to the overall budget and CH4 reducing the budget by less than 1%. In comparison with the CO2 fluxes measured by eddy covariance, the gradient technique underestimated the effluxes during the main winter period by 40% but yielded similar fluxes on a seasonal basis. Cumulative budgets of CO2 were smaller than emission reported for other sub-alpine meadows in the Swiss Alps and the Rocky Mountains. It remains unclear how GHG emissions are altered by changes in climate and according snow conditions.

  8. Anthropogenic effects on greenhouse gas (CH4 and N2O) emissions in the Guadalete River Estuary (SW Spain).

    Science.gov (United States)

    Burgos, M; Sierra, A; Ortega, T; Forja, J M

    2015-01-15

    Coastal areas are subject to a great anthropogenic pressure because more than half of the world's population lives in its vicinity causing organic matter inputs, which intensifies greenhouse gas emissions into the atmosphere. Dissolved concentrations of CH4 and N2O have been measured seasonally during 2013 in the Guadalete River Estuary, which flows into the Cadiz Bay (southwestern Spanish coast). It has been intensely contaminated since 1970. Currently it receives wastewater effluents from cities and direct discharges from nearby agriculture crop. Eight sampling stations have been established along 18 km of the estuary. CH4 and N2O were measured using a gas chromatograph connected to an equilibration system. Additional parameters such as organic matter, dissolved oxygen, nutrients and chlorophyll were determinate as well, in order to understand the relationship between physicochemical and biological processes. Gas concentrations increased from the River mouth toward the inner part, closer to the wastewater treatment plant discharge. Values varied widely within 21.8 and 3483.4 nM for CH4 and between 9.7 and 147.6 nM for N2O. Greenhouse gas seasonal variations were large influenced by the precipitation regime, masking the temperature influence. The Guadatete Estuary acted as a greenhouse gas source along the year, with mean fluxes of 495.7 μmol m(-2)d(-1) and 92.8 μmol m(-2)d(-1) for CH4 and N2O, respectively.

  9. NH3, N2O and CH4 emissions during passively aerated composting of straw-rich pig manure

    NARCIS (Netherlands)

    Szanto, G.L.; Hamelers, H.V.M.; Rulkens, W.H.; Veeken, A.H.M.

    2007-01-01

    Straw-rich manure from organic pig farming systems was composted in passively aerated static piles to estimate the effect of monthly turning on organic matter degradation and NH3, N2O and CH4 emissions. Turning enhanced the rate of drying and degradation. The four-month treatment degraded 57 ± 3% of

  10. CH4 and N2O emissions embodied in international trade of meat

    Science.gov (United States)

    Caro, Dario; LoPresti, Anna; Davis, Steven J.; Bastianoni, Simone; Caldeira, Ken

    2014-11-01

    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 (CH4) and nitrous oxide (N2O). Following IPCC guidelines, we estimate non-CO2 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 CO2-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 CO2-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 CO2-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 CO2-eq, respectively. Emissions factor of meat production (i.e. CO2-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.

  11. 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

  12. High-Frequency, Automated Measurements of CO2, N2O and CH4 from Forested Soils

    Science.gov (United States)

    Savage, K. E.; Davidson, E. A.; Phillips, R. L.

    2011-12-01

    Carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are the most important anthropogenic greenhouse gases. Soils are the dominant natural source of N2O, and fertilized agricultural soils are a major source of increasing anthropogenic N2O. Anthropogenic sources of CH4 include rice cultivation, while wetlands are a significant natural source, and upland soils are a natural CH4 sink. While most anthropogenic CO2 is derived from fossil fuel combustion, a significant fraction is from land use change, including a portion from loss of soil carbon. Soils play a central role as sources and sinks of the three most important anthropogenic greenhouse gases of the 21st century, CO2, CH4, and N2O. Variation in soil moisture can be very dynamic, and it is one of the dominant factors controlling soil aeration, and hence the balance between aerobic (CO2 producing) and anaerobic (CH4 producing) respiration. The production and consumption of N2O is also highly dependent on spatial and temporal variation in soil moisture. Although technologies for high frequency, precise measurements of CO2 have been available for years, methods for measuring soil fluxes of CH4 and N2O at high temporal frequency have been hampered by lack of appropriate technology for in situ real-time measurements. We utilized a previously developed automated chamber system for measuring CO2 efflux (Licor 6252 IRGA) from soils, and configured it to run in-line with a new model quantum cascade laser (QCL) system which measures N2O and CH4 (Aerodyne model QC-TILDAS-CS). The QCL is thermoelectrically cooled and uses a 76-meter path length, 0.5 liter volume, and multiple pass absorption cell for sampling. The QCL sampling frequency is 10Hz, and its range is 0.3 to 3000 ppb for N2O with a sensitivity of 0.3 ppb, and 0.5 to 5000 ppb for CH4 with a sensitivity of 0.5 ppb. Six sampling chambers, with corresponding soil water content and soil temperature sensors, were deployed at the Howland Forest ME, in an upland

  13. Phosphorus addition mitigates N2O and CH4 emissions in N-saturated subtropical forest, SW China

    Science.gov (United States)

    Yu, Longfei; Wang, Yihao; Zhang, Xiaoshan; Dörsch, Peter; Mulder, Jan

    2017-06-01

    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.

  14. Seasonal variation analysis of atmospheric CH4,N2O and CO2 in Tianjin offshore area

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The concentrations of CH4, N2O and CO2 at the sea level were observed from November 2007 to August 2008 in order to study the greenhouse gases in the Tianjin offshore area of Bohai Sea. CH4 concentrations varied from 1.87 to 2.61 ppm with the highest value appearing in summer and the lowest in winter. The concentration range of N2O was 319.3 to 347.7 ppb, with the maximal value appearing in winter. CO2 was higher in the heating season than in non-heating season in this area. Concentrations of the three greenhouse gases in the study area exceeded the 2005 global background values. Backward trajectory model was used to analyze the sources. All three gases were influenced evidently by continental sources in the inshore area during the sampling periods. Every gas was compared with each other by correlation analysis, showing that the correlation of CO2 and N2O was more significant than to CH4 and their relationship with meteorological factors was consistent. It can be concluded these three greenhouse gases may be influenced by some similar sources, especially for CO2 and N2O.

  15. 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.

  16. 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.

  17. Etch characteristics of magnetic tunnel junction materials using bias pulsing in the CH4/N2O inductively coupled plasma.

    Science.gov (United States)

    Jeon, Min Hwan; Youn, Ji Youn; Yang, Kyung Chae; Yun, Deok Hyun; Lee, Du Yeong; Shim, Tae Hun; Park, Jea Gun; Yeom, Geun Young

    2014-12-01

    The etch characteristics of magnetic tunneling junction (MTJ) related materials such as CoFeB, MgO, FePt, Ru, and W as hard mask have been investigated as functions of rf pulse biasing, substrate heating, and CH4/N2O gas combination in an inductively coupled plasma system. When CH4/N2O gas ratio was varied, at CH4/N2O gas ratio of 2:1, not only the highest etch rates but also the highest etch selectivity over W could be obtained. By increasing the substrate temperature, the linear increase of both the etch rates of MTJ materials and the etch selectivity over W could be obtained. The use of the rf pulse biasing improved the etch selectivity of the MTJ materials over hard mask such as W further. The surface roughness and residual thickness remaining on the etched surface of the CoFeB were also decreased by using rf pulse biasing and with the decrease of rf duty percentage. The improvement of etch characteristics by substrate heating and rf pulse biasing was possibly related to the formation of more stable and volatile etch compounds and the removal of chemically reacted compounds more easily on the etched CoFeB surface. Highly selective etching of MTJ materials over the hard mask could be obtained by using the rf pulse biasing of 30% of duty ratio and by increasing the substrate temperature to 200 degrees C in the CH4/N2O (2:1) plasmas.

  18. The Impact of Current CH4 and N2O Loss Process Uncertainties on Model Calculated Ozone and Global Lifetimes

    Science.gov (United States)

    Fleming, E. L.; Burkholder, J. B.; Kurylo, M. J., III; Jackman, C. H.

    2015-12-01

    The atmospheric loss processes of CH4 and N2O, their estimated uncertainties, lifetimes, and impacts on ozone abundance and long-term trends are examined using atmospheric model calculations and updated kinetic and photochemical parameters and uncertainty factors from SPARC (2013). Uncertainties in CH4 loss due to reaction with OH and O(1D) have relatively small impacts on present day calculated global total ozone (±0.2-0.3%), with the OH+CH4 uncertainty impacting tropospheric ozone by ±3-5%. Uncertainty in the Cl+CH4 reaction affects the amount of chlorine in radical vs. reservoir forms and has a modest impact on present day SH polar ozone (~±6%), and on the rate of past SH polar ozone decline and future recovery. The O(1D)+N2O reaction has uncertainty in both the total rate coefficient and branching ratio for the O2+N2 and 2*NO product channels. This uncertainty results in a substantial range in present day stratospheric odd nitrogen (±10-25%) and global total ozone (±1-2.5%). This uncertainty also impacts the rate of past global total ozone decline and future recovery, with a range in future ozone projections of ±1-1.5% by 2100, relative to present day. The uncertainty ranges in calculated CH4 and N2O global lifetimes are also examined: these ranges are significantly reduced when using the updated SPARC estimated uncertainties compared with those from JPL-2010.

  19. Soil trace gas emissions (CH4 and N2O) offset the CO2 uptake in poplar short rotation coppice

    Science.gov (United States)

    Zenone, Terenzio; Zona, Donatella; Gelfand, Iya; Gielen, Bert; camino serrano, Marta; Ceulemans, Reinhart

    2015-04-01

    The need for renewable energy sources will lead to a considerable expansion in the planting of dedicated fast-growing biomass crops across Europe. Among them poplar (Populus spp) is the most widely planted as short rotation coppice (SRC) and an increase in the surface area of large-scale SRC poplar plantations might thus be expected. In this study we report the greenhouse gas fluxes (GHG) of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) measured using the eddy covariance technique in a SRC plantation for bioenergy production during the period 2010-2013. The plantation was established in April 2010 on 18.4 ha of former agricultural land with a density of 8000 plants ha-1; the above-ground biomass was harvested on February 2012 and 2014.The whole GHG balance of the four years of the study was 1.90 (± 1.37) Mg CO2eq ha-1; this indicated that soil trace gas emissions offset the CO2 uptake by the plantation. CH4 and N2O almost equally contributed to offset the CO2 uptake of -5.28 (±0.67) Mg CO2eq ha-1 with an overall emission of 3.56 (± 0.35) Mg CO2eq ha-1 of N2O and of 3.53 (± 0.85) Mg CO2eq ha-1 of CH4. N2O emissions mostly occurred during a single peak a few months after the site was converted into SRC and represented 44% of the entire N2O loss during the entire study. Accurately capturing these emission events proved to be critical for correct estimates of the GHG balance. The self-organizing map (SOM) technique graphically showed the relationship between the CO2 fluxes and the principal environmental variables but failed to explain the variability of the soil trace gas emissions. The nitrogen content in the soil and the water table depth were the two drivers that best explained the variability in N2O and CH4 respectively. This study underlines the importance of the "non-CO2 GHG" on the overall balance as well as the impact of the harvest on the CO2 uptake rate. Further long-term investigations of soil trace gas emissions should also monitor the N

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

    Directory of Open Access Journals (Sweden)

    L. Farías

    2010-09-01

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

  1. 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.

  2. 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.

  3. [Effects of no-tillage and fertilization on paddy soil CH4 and N2O emissions and their greenhouse effect in central China].

    Science.gov (United States)

    Dai, Guang-zhao; Li, Cheng-fang; Cao, Cou-gui; Zhan, Ming; Tong, Le-ga; Mei, Shao-hua; Zhai, Zhong-bing; Fan, Duan-yang

    2009-09-01

    By using static chamber-gas chromatographic techniques, the CH4 and N2O emissions from the paddy soil in southeast Hubei were measured. Four treatments were installed, i.e., no-tillage plus no-fertilization (NT0), conventional tillage plus no-fertilization (CT0), no-tillage plus fertilization (NTC), and conventional tillage plus fertilization (CTC). In all treatments, the CH4 emission had a seasonal variation of increasing first and decreasing then, while the N2O emission had no significant seasonal variation. Fertilization increased the CH4 and N2O emissions significantly. NT0 increased the CH4 emission and decreased the N2O emission significantly, compared with CT0; NTC only decreased the CH4 emission and increased the N2O emission slightly, compared with CTC. The analysis on the integrated greenhouse effect of CH4 and N2O showed that NT0 increased the effect by 25.9%, compared with CT0, while NTC decreased the effect by 10.1%, compared with CTC. Therefore, a reasonable arrangement of fertilization and no-tillage could reduce the integrated greenhouse effect of CH4 and N2O from paddy field.

  4. Quick Measurement of CH4, CO2 and N2O Emissions from a Short-Plant Ecosystem

    Institute of Scientific and Technical Information of China (English)

    王跃思; 王迎红

    2003-01-01

    Combining improved injector, gas line and valve-driving models, a gas chromatograph (GC) equippedwith Hydrogen Flame Ionization Detector (FID) and Electron Capture Detector (ECD), can measureCH4, CO2, and N2O simultaneously in an air sample in four minutes. Test results show that the systemhas high sensitivity, resolution, and precision; the linear response range of the system meets the requirementof flux measurements in situ. The system is suitable for monitoring fluxes of the main greenhouse gases ina short-plant field since it is easy to use, efficacious, and constant and reliable in collecting data.

  5. Spatial and temporal patterns of CH4 and N2O fluxes in terrestrial ecosystems of North America during 1979–2008: application of a global biogeochemistry model

    Directory of Open Access Journals (Sweden)

    C. Lu

    2010-09-01

    Full Text Available Continental-scale estimations of terrestrial methane (CH4 and nitrous oxide (N2O fluxes over a long time period are crucial to accurately assess the global balance of greenhouse gases and enhance our understanding and prediction of global climate change and terrestrial ecosystem feedbacks. Using a process-based global biogeochemical model, the Dynamic Land Ecosystem Model (DLEM, we quantified simultaneously CH4 and N2O fluxes in North America's terrestrial ecosystems from 1979 to 2008. During the past 30 years, approximately 14.69 ± 1.64 T g C a−1 (1 T g = 1012 g of CH4, and 1.94 ± 0.1 T g N a−1 of N2O were released from terrestrial ecosystems in North America. At the country level, both the US and Canada acted as CH4 sources to the atmosphere, but Mexico mainly oxidized and consumed CH4 from the atmosphere. Wetlands in North America contributed predominantly to the regional CH4 source, while all other ecosystems acted as sinks for atmospheric CH4, of which forests accounted for 36.8%. Regarding N2O emission in North America, the US, Canada, and Mexico contributed 56.19%, 18.23%, and 25.58%, respectively, to the continental source over the past 30 years. Forests and croplands were the two ecosystems that contributed most to continental N2O emission. The inter-annual variations of CH4 and N2O fluxes in North America were mainly attributed to year-to-year climatic variability. While only annual precipitation was found to have a significant effect on annual CH4 flux, both mean annual temperature and annual precipitation were significantly correlated to annual N2O flux. The regional estimates and spatiotemporal patterns of terrestrial ecosystem CH4 and N2O fluxes in North America generated in this study provide useful information for global change research and policy making.

  6. Fluxes of CO2, CH4 and N2O from soil of burned grassland savannah of central Africa

    Directory of Open Access Journals (Sweden)

    R. Valentini

    2010-06-01

    Full Text Available Grassland savannah ecosystems subject to frequent fires are considered to have an almost neutral carbon balance, as the C released during burning mostly balance the C fixed by the photosynthetic process. However, burning might modify the net soil-atmosphere exchange of GHGs in the post burning phase so that the radiative balance of the site might shift from neutrality. In the present study the impact of fire on soil fluxes of CO2, CH4 and N2O was investigated in a grassland savannah (Congo Brazzaville where high frequency burning is the typical management form of the region. An area was preserved for one season from annual burning and was used as "unburned" treatment. Two field campaigns were carried on at different time length from the fire event, 1 month, in the middle of the dry season, and 8 months after, at the end of the growing season. CO2, CH4 and N2O fluxes, as well as several soil parameters, were measured in each campaign from burned and unburned plots. Rain events were simulated at each campaign to evaluate magnitude and length of the generated GHG flux pulses. In laboratory experiments, on soil samples from the two treatments, microbial biomass, net N mineralization, net nitrification, N2O, NO and CO2 emissions were analyzed in function of soil water and/or temperature variations. Results showed that fire had a significant effect on GHG fluxes but the effect was transient, as after 8 months differences between treatments were no longer significant. One month after burning CO2 soil emissions were significantly lower in the burned plots, CH4 fluxes were dominated by net emissions rather than net consumption in the unburned area and fire shifted the CH4 flux distribution towards more negative values. No significant effect of fire was observed in the field on N2O fluxes. It was assumed that the low water content was the main limiting factor as in fact laboratory data showed that only above 75% of water saturation, N2O emissions

  7. 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

  8. Effects of fertilization on microbial abundance and emissions of greenhouse gases (CH4 and N2O) in rice paddy fields.

    Science.gov (United States)

    Fan, Xianfang; Yu, Haiyang; Wu, Qinyan; Ma, Jing; Xu, Hua; Yang, Jinghui; Zhuang, Yiqing

    2016-02-01

    This study is to explore effects of nitrogen application and straw incorporation on abundance of relevant microbes and CH 4 and N2O fluxes in a midseason aerated rice paddy field. Fluxes of CH 4 and N2O were recorded, and abundance of relevant soil microbial functional genes was determined during rice-growing season in a 6-year-long fertilization experiment field in China. Results indicate that application of urea significantly changed the functional microbial composition, while the influence of straw incorporation was not significant. Application of urea significantly decreased the gene abundances of archaeal amoA and mcrA, but it significantly increased the gene abundances of bacterial amoA. CH 4 emission was significantly increased by fresh straw incorporation. Incorporation of burnt straw tended to increase CH 4 emission, while the urea application had no obvious effect on CH 4 emission. N2O emission was significantly increased by urea application, while fresh or burnt straw incorporation tended to decrease N2O emission. The functional microbial composition did not change significantly over time, although the abundances of pmoA, archaeal amoA, nirS, and nosZ genes changed significantly. The change of CH 4 emission showed an inverse trend with the one of the N2O emissions over time. To some extent, the abundance of some functional genes in this study can explain CH 4 and N2O emissions. However, the correlation between CH 4 and N2O emissions and the abundance of related functional genes was not significant. Environmental factors, such as soil Eh, may be more related to CH 4 and N2O emissions.

  9. Tree species influence soil-atmosphere fluxes of the greenhouse gases CO2, CH4 and N2O

    Science.gov (United States)

    Steffens, Christina; Vesterdal, Lars; Pfeiffer, Eva-Maria

    2016-04-01

    In the temperate zone, forests are the greatest terrestrial sink for atmospheric CO2, and tree species affect soil C stocks and soil CO2 emissions. When considering the total greenhouse gas (GHG) balance of the forest soil, the relevant GHGs CH4 and N2O should also be considered as they have a higher global warming potential than CO2. The presented data are first results from a field study in a common garden site in Denmark where tree species with ectomycorrhizal colonization (beech - Fagus sylvatica, oak - Quercus robur) and with arbuscular mycorrhizal colonization (maple - Acer pseudoplatanus, ash - Fraxinus excelsior) have been planted in monocultures in adjacent blocks of about 0.25 ha in the year 1973 on former arable land. The soil-atmosphere fluxes of all three gases were measured every second week since August 2015. The hypothesis is that the total GHG efflux from forest soil would differ between species, and that these differences could be related to the type of mycorrhizal association and leaf litter quality. Preliminary results (August to December 2015) indicate that tree species influence the fluxes (converted to CO2-eq) of the three GHGs. Total soil CO2 efflux was in the low end of the range reported for temperate broadleaved forests but similar to the measurements at the same site approximately ten years ago. It was highest under oak (9.6±2.4 g CO2 m-2 d-1) and lowest under maple (5.2±1.6 g CO2 m-2 d-1). In contrast, soil under oak was a small but significant sink for CH4(-0.005±0.003 g CO2-eq m-2 d-1), while there were almost no detectable CH4 fluxes in maple. Emissions of N2O were highest under beech (0.6±0.6 g CO2-eq m-2 d-1) and oak (0.2±0.09 g CO2-eq m-2 d-1) and lowest under ash (0.03±0.04 g CO2-eq m-2 d-1). In the total GHG balance, soil CH4 uptake was negligible (≤0.1% of total emissions). Emissions of N2O (converted to CO2-eq) contributed arbuscular mycorrhiza and produce leaf litter with a lower lignin:N ratio.

  10. Archaeal Ammonia Oxidizers and Total Production of N2O and CH4 in Arctic Polar Desert Soils

    Science.gov (United States)

    Brummell, Martin; Robert, Stan; Bodrossy, Levente; Abell, Guy; Siciliano, Steven

    2014-05-01

    Ammonia-oxidizing Archaea are abundant in Arctic desert soils and appear to be responsible for the majority of ammonia oxidation activity in these cold and dry ecosystems. We used DNA microarrays to characterize the microbial community consisting of ammonia-oxidizing Archaea and methane-oxidizing Bacteria in three polar deserts from Ellesmere Island, Canada. Patterns of net greenhouse gas production, including production and consumption of CO2, CH4, and N2O were compared with community relative richness and abundance in a structural equation model that tested causal hypotheses relating edaphic factors to the biological community and net gas production. We extracted and amplified DNA sequences from soils collected at three polar deserts on Ellesmere Island in the Canadian high Arctic, and characterized the community structure using DNA microarrays. The functional genes Archaeal AmoA and pMMO were used to compare patterns of biological community structure to the observed patterns of net greenhouse gas production from those soils, as measured in situ. Edaphic factors including water content, bulk density, pH, and nutrient levels such as nitrate, ammonia, and extractable organic carbon were also measured for each soil sample, resulting in a highly multivariate dataset. Both concentration and net production of the three greenhouse gases were correlated, suggesting underlying causal factors. Edaphic factors such as soil moisture and pH had important, direct effects on the community composition of both functional groups of microorganisms, and pH further had a direct effect on N2O production. The structural relationship between the examined microbial communities and net production of both N2O and CH4 was strong and consistent between varying model structures and matrices, providing high confidence that this model relationship accurately reflects processes occurring in Arctic desert soils.

  11. Simulated nitrogen deposition reduces CH4 uptake and increases N2O emission from a subtropical plantation forest soil in southern China.

    Science.gov (United States)

    Wang, Yongsheng; Cheng, Shulan; Fang, Huajun; Yu, Guirui; Xu, Minjie; Dang, Xusheng; Li, Linsen; Wang, Lei

    2014-01-01

    To date, few studies are conducted to quantify the effects of reduced ammonium (NH4+) and oxidized nitrate (NO3-) on soil CH4 uptake and N2O emission in the subtropical forests. In this study, NH4Cl and NaNO3 fertilizers were applied at three rates: 0, 40 and 120 kg N ha(-1) yr(-1). Soil CH4 and N2O fluxes were determined twice a week using the static chamber technique and gas chromatography. Soil temperature and moisture were simultaneously measured. Soil dissolved N concentration in 0-20 cm depth was measured weekly to examine the regulation to soil CH4 and N2O fluxes. Our results showed that one year of N addition did not affect soil temperature, soil moisture, soil total dissolved N (TDN) and NH4+-N concentrations, but high levels of applied NH4Cl and NaNO3 fertilizers significantly increased soil NO3(-)-N concentration by 124% and 157%, respectively. Nitrogen addition tended to inhibit soil CH4 uptake, but significantly promoted soil N2O emission by 403% to 762%. Furthermore, NH4+-N fertilizer application had a stronger inhibition to soil CH4 uptake and a stronger promotion to soil N2O emission than NO3(-)-N application. Also, both soil CH4 and N2O fluxes were driven by soil temperature and moisture, but soil inorganic N availability was a key integrator of soil CH4 uptake and N2O emission. These results suggest that the subtropical plantation soil sensitively responses to atmospheric N deposition, and inorganic N rather than organic N is the regulator to soil CH4 uptake and N2O emission.

  12. Simulated nitrogen deposition reduces CH4 uptake and increases N2O emission from a subtropical plantation forest soil in southern China.

    Directory of Open Access Journals (Sweden)

    Yongsheng Wang

    Full Text Available To date, few studies are conducted to quantify the effects of reduced ammonium (NH4+ and oxidized nitrate (NO3- on soil CH4 uptake and N2O emission in the subtropical forests. In this study, NH4Cl and NaNO3 fertilizers were applied at three rates: 0, 40 and 120 kg N ha(-1 yr(-1. Soil CH4 and N2O fluxes were determined twice a week using the static chamber technique and gas chromatography. Soil temperature and moisture were simultaneously measured. Soil dissolved N concentration in 0-20 cm depth was measured weekly to examine the regulation to soil CH4 and N2O fluxes. Our results showed that one year of N addition did not affect soil temperature, soil moisture, soil total dissolved N (TDN and NH4+-N concentrations, but high levels of applied NH4Cl and NaNO3 fertilizers significantly increased soil NO3(--N concentration by 124% and 157%, respectively. Nitrogen addition tended to inhibit soil CH4 uptake, but significantly promoted soil N2O emission by 403% to 762%. Furthermore, NH4+-N fertilizer application had a stronger inhibition to soil CH4 uptake and a stronger promotion to soil N2O emission than NO3(--N application. Also, both soil CH4 and N2O fluxes were driven by soil temperature and moisture, but soil inorganic N availability was a key integrator of soil CH4 uptake and N2O emission. These results suggest that the subtropical plantation soil sensitively responses to atmospheric N deposition, and inorganic N rather than organic N is the regulator to soil CH4 uptake and N2O emission.

  13. [NH3, N2O, CH4 and CO2 emissions from growing process of caged broilers].

    Science.gov (United States)

    Zhou, Zhong-Kai; Zhu, Zhi-Ping; Dong, Hong-Min; Chen, Yong-Xing; Shang, Bin

    2013-06-01

    To obtain Ammonia and greenhouse gas (GHG) emission factors of caged broilers, ammonia (NH3), methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) emissions of broilers aged 0 d to 42 days were monitored in caged broilers production systems located in Shandong province. Gas concentrations of incoming and exhaust air streams were measured by using INNOVA 1312 multi-gas monitor with multi-channel samplers. Building ventilation rates were determined by on site FANS (Fan Assessment Numeration System) measurement systems. The NH3 emission factors showed a trend of increase at the beginning and then decreased with the broiler ages. The NH3 emission rates were 8.5 to 342.1 mg x (d x bird)(-1) and the average daily emission rate was 137.9 mg x (d x bird)(-1) [48.6 g x (d x AU)(-1)] over the 42-d period. The GHGs emission rates were 19.5-351.9 mg x (d x bird)(-1) with an average of 154.5 mg x (d x bird)(-1) [54.4 g x (d x AU)(-1)] for CH4, and 2.2- 152.9 g x (d x bird)(-10 with an average of 65.9 g x (d x bird)(-1) [23.2 kg x (d x AU)(-1)] for CO2. No emission of N2O was observed. The CH4 and CO2 emission rates increased with the increase of broilers ages. The total NH3 emission over the 42 d growing period averaged (5.65 +/- 1.02) g x (bird x life cycle)(-1). The NH3 emission contribution in different growth phase to the total emission were 33.6% in growth phase 1 (0-17 day, GP1), 36.4% in GP2 (18-27 days), and 29.9% in GP3 (28-42 days), respectively. The NH3 emission in GP2 was significantly higher than emission in GP1 and GP3. CH4 and CO2 cumulative emission rates were (6.30 +/- 0.16) g x (bird(-1) x life cycle)(-1) and (2.68 +/- 0.18) kg x (bird x life cycle)(-1), respectively. The cumulative emission rates of CH4 and CO2 in GP3 were significantly higher than emission rates in GP2 and in GP1, accounting for 50% of total emissions. The results of this study could provide the data support for mitigation of gas emission from broilers production.

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

    Directory of Open Access Journals (Sweden)

    T. Röckmann

    2013-02-01

    Full Text Available 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 to measure δ13C-CH4, δ15N-N2O and δ18O-N2O isotope ratios in one ice core sample, 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. A gold catalyst is used to oxidize CO to CO2 in the air sample without affecting the CH4 and N2O sample. CH4 and N2O are then separated from N2, O2, Ar and CO2 before they get pre-concentrated and separated by gas chromatography. While the separated N2O sample is immediately analysed in the mass spectrometer, 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 increase the time for δ13C-CH4 analysis 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. After the extraction of the air from the ice core sample, the analysis of CH4 and N2O takes 42 min. The setup is calibrated by analyzing multiple isotope reference gases that were injected over bubble-free-ice samples. We show a comparison of ice core

  15. Diffosion of H2,CO,N2,O2 and CH4 Through Nanoporous Carbon Membranes%H2,CO,N2,O2和CH4在碳膜中的扩散

    Institute of Scientific and Technical Information of China (English)

    吴志强; 刘志平; 汪文川; 范益群; 徐南平

    2008-01-01

    Diffusion of pure H2,CO,N2,O2and CH4 gases through nanoporous carbon membrane is investigated by carrying out non-equilibrium molecular dynamics(NEMD)simulations.The flux,transport diflusivity and acti-vation energy for the pure gases diffusing through carbon membranes with various pore widths were investigated.The simulation results reveal that transport diffusivity increases with temperature and pore width.and its values port diflusivities are comparablc With that of Rao and Sircar(J.Membr.Sci.,1996).indicating the NEMD simula-tion method iS a good toO]for predicting the transport diflusivities for gases in porous materialS.which iS always difficult to be accurately measured by experiments.

  16. Plant species diversity reduces N2O but not CH4 emissions from constructed wetlands under high nitrogen levels.

    Science.gov (United States)

    Han, Wenjuan; Shi, Mengmeng; Chang, Jie; Ren, Yuan; Xu, Ronghua; Zhang, Chongbang; Ge, Ying

    2017-02-01

    Constructed wetlands (CWs) have been widely used for treating wastewater. CWs also are the sources of greenhouse gas (GHG) due to high pollutant load. It has been reported that plant species diversity can enhance nitrogen (N) removal efficiency in CWs for treating wastewater. However, the influence of plant species diversity on GHG emissions from CWs in habitats with high N levels still lack research. This study established four species richness levels (1, 2, 3, 4) and 15 species compositions by using 75 simulated vertical flow CWs microcosms to investigate the effects of plant species diversity on the GHG emissions and N removal efficiency of CWs with a high N level. Results showed plant species richness reduced nitrous oxide (N2O) emission and N (NO3(-)-N, NH4(+)-N, and TIN) concentrations in wastewater, but had no effect on methane (CH4) emission. Especially, among the 15 compositions of plant species, the four-species mixture emitted the lowest N2O and had under-depletion of N (DminTIN CWs for treating wastewater with a high N level.

  17. 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

  18. 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....... Pig slurry was stored with or without a straw crust, and with or without interception of precipitation, i.e., four treatments, in two randomized blocks. Emissions of total reduced S (mainly H2S) and p-cresol, but not skatole, were reduced by the straw crust. Total GHG emissions were 0.01–0.02 kg CO2......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...

  19. Aerial Photography Estimation of CH4 and N2O Emissions from Adelie Penguins During 1983-2012 in Victoria Land, Antarctic

    Science.gov (United States)

    He, H.; Li, X.; Cheng, X.

    2016-12-01

    Sea animals are the "bio-indicators" of the climate change in the Antarctic. The abundant nutrient components in their excreta such as carbon (C) and nitrogen (N) promote the emissions of greenhouse gases (GHGs) including methane (CH4) and nitrous oxide (N2O). Adélie Penguins are important sea animals, their colonies therefore become the potential "hotspots" of the GHGs emissions. Some field observations have been carried out to study the penguin excreta on CH4 and N2O emissions in the Antarctic peninsula. However, due to the lacking of the penguin population data, the total emissions of GHGs have not been estimated at regional scale. This study aimed to extract penguin information from two period aerial photographs respectively in 1983 and 2012 using object-oriented method in Victoria Land, Antarctic, and then estimate the Adélie penguin populations on Inexpressible Island combined with the shadow analysis. Meanwhile, a GHGs model was developed to estimate CH4 and N2O emissions from Adelie penguins based on the CH4 and N2O fluxes of penguin guanos, the number of penguins, and the fresh weight of penguin guanos and so on. The results indicated that object-oriented method was effective in penguin information extraction from high-resolution images, and there were 17120 and 21183 Adélie penguins respectively in 1983 and 2012, respectively. The main reasons for the increase in penguin populations from 1983 to 2012 might be explained from physical environment and biological environment, such as the rising temperatures and reduced Antarctic toothfishes. And the total CH4 and N2O emissions from penguins on Inexpressible Island during breeding season were 246 kg CH4 and 2.67 kg N2O in 1983, and 304 kg CH4 and 3.31 kg N2O in 2012. Our study aimed to provide important reference value for the estimation of GHG budget in Antarctic.

  20. Adsorption of CO(2), CH(4), N(2)O, and N(2) on MOF-5, MOF-177, and zeolite 5A.

    Science.gov (United States)

    Saha, Dipendu; Bao, Zongbi; Jia, Feng; Deng, Shuguang

    2010-03-01

    Adsorption equilibrium and kinetics of CO(2), CH(4), N(2)O, and N(2) on two newly discovered adsorbents, metal-organic frameworks MOF-5 and MOF-177 and one traditional adsorbent, zeolite 5A were determined to assess their efficacy for CO(2), CH(4), and N(2)O removal from air and separation of CO(2) from CH(4) in pressure swing adsorption processes. Adsorption equilibrium and kinetics data for CO(2), CH(4), N(2)O, and N(2) on all three adsorbents were measured volumetrically at 298K and gas pressures up to 800 Torr. Adsorption equilibrium capacities of CO(2) and CH(4) on all three adsorbents were determined gravimetrically at 298 K and elevated pressures (14 bar for CO(2) and 100 bar for CH(4)). The Henry's law and Langmuir adsorption equilibrium models were applied to correlate the adsorption isotherms, and a classical micropore diffusion model was used to analyze the adsorption kinetic data. The adsorption equilibrium selectivity was calculated from the ratio of Henry's constants, and the adsorbent selection parameter for pressure swing adsorption processes were determined by combining the equilibrium selectivity and working capacity ratio. Based on the selectivity and adsorbent selection parameter results, zeolite 5A is a better adsorbent for removing CO(2) and N(2)O from air and separation of CO(2) from CH(4), whereas MOF-177 is the adsorbent of choice for removing CH(4) from air. However, both MOF adsorbents have larger adsorption capacities for CO(2) and CH(4) than zeolite 5A at elevated pressures, suggesting MOF-5 and MOF-177 are better adsorbents for CO(2) and CH(4) storage. The CH(4) adsorption capacity of 22 wt.% on MOF-177 at 298K and 100 bar is probably the largest adsorption uptake of CH(4) on any dry adsorbents. The average diffusivity of CO(2), CH(4) and N(2)O in MOF-5 and MOF-177 is in the order of 10(-9) m(2)/s, as compared to 10(-11) m(2)/s for CO(2), CH(4) and N(2)O in zeolite 5A. The effects of gas pressure on diffusivity for different adsorabte

  1. Spatial and temporal patterns of CH4 and N2O fluxes in terrestrial ecosystems of North America during 1979–2008: application of a global biogeochemistry model

    Directory of Open Access Journals (Sweden)

    G. Chen

    2010-04-01

    Full Text Available Continental-scale estimations of terrestrial methane (CH4 and nitrous oxide (N2O fluxes over a long time period are crucial to accurately assess the global balance of greenhouse gases and enhance our understanding and prediction of global climate change and terrestrial ecosystem feedbacks. Using a process-based global biogeochemical model, the Dynamic Land Ecosystem Model (DLEM, we quantified simultaneously CH4 and N2O fluxes in North America's terrestrial ecosystems from 1979 to 2008. During the past 30 years, approximately 14.69±1.64 T g C a−1 (1 T g=1012 g of CH4, and 1.94±0.16 T g N a−1 of N2O were released from terrestrial ecosystems in North America. At the country level, both the United States and Canada acted as CH4 sources to the atmosphere, but Mexico mainly oxidized and consumed CH4 from the atmosphere. Wetlands in North America contributed predominantly to the regional CH4 source, while all other ecosystems acted as sinks for atmospheric CH4, of which forests accounted for 36.8%. Regarding N2O emission in North America, the United States, Canada, and Mexico contributed 56.19%, 18.23%, and 25.58%, respectively, to the continental source over the past 30 years. Forests and croplands were the two ecosystems that contributed most to continental N2O emission. The inter-annual variations of CH4 and N2O fluxes in North America were mainly attributed to year-to-year climatic variability. While only annual precipitation was found to have a significant effect on annual CH4 flux, both mean annual temperature and annual precipitation were significantly correlated to annual N2O flux. The regional estimates and spatiotemporal patterns of terrestrial ecosystem CH4 and N2O fluxes in North America generated in this study provide useful information for global change research and policy making.

  2. Contribution of winter fluxes to the annual CH4, CO2 and N2O emissions from freshwater marshes in the Sanjiang Plain

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Wetlands at the interface of the terrestrial and aquatic ecosystems are intensive sites for mineralization of organic matter,but the contribution of winter season fluxes of CH4, CO2 and N2O from wetland ecosystems to annual budgets is poorly known. By using the static opaque chamber and GC techniques, fluxes of CH4, CO2 and N2O at two freshwater marshes in the Sanjiang Plain were measured during the winter seasons of 2002/2003 and 2003/2004 with contrasting snow conditions and flooding regimes. The results showed that there were significant interannual and spatial differences in CH4, CO2 and N2O fluxes. The Carex lasiocarpa marsh emitted more CH4 and CO2 while absorbed less N2O than the Deyeuxia angustifolia marsh during the winter seasons. Over the winter season,emissions of CH4, CO2 and N2O ranged from 0.42 to 2.41 gC/m2, from 24.13 to 50.16 gC/m2, and from -25.20 to -148.96 mgN/m2,respectively. The contributions of winter season CH4 and CO2 emission to the annual budgets were 2.32%-4.62% and 22.17%-27.97%, respectively. Marshes uptake N2O during the freezing period, while release N2O during the thawing period. The winter uptake equaled to 13.70%-86.69% of the growing-season loss. We conclude that gas exchange between soil/snow and the atmosphere in the winter season contributed greatly to the annual budgets and cannot be ignored in a cool temperate freshwater marsh in Northeast China.

  3. Effects of elevated atmospheric CO2, prolonged summer drought and temperature increase on N2O and CH4 fluxes in a temperate heathland

    DEFF Research Database (Denmark)

    Carter, Mette Sustmann; Ambus, Per; Albert, Kristian Rost

    2011-01-01

    In temperate regions, climate change is predicted to increase annual mean temperature and intensify the duration and frequency of summer droughts, which together with elevated atmospheric carbon dioxide (CO2) concentrations, may affect the exchange of nitrous oxide (N2O) and methane (CH4) between...... change manipulations were initiated. The soil was generally a net sink for atmospheric CH4. Elevated temperature (T) increased the CH4 uptake by on average 10 μg C m−2 h−1, corresponding to a rise in the uptake rate of about 20%. However, during winter elevated CO2 (CO2) reduced the CH4 uptake, which...

  4. Soil-atmospheric exchange of CO2, CH4, and N2O in three subtropical forest ecosystems in southern China

    Science.gov (United States)

    Tang, X.; Liu, S.; Zhou, G.; Zhang, Dongxiao; Zhou, C.

    2006-01-01

    The magnitude, temporal, and spatial patterns of soil-atmospheric greenhouse gas (hereafter referred to as GHG) exchanges in forests near the Tropic of Cancer are still highly uncertain. To contribute towards an improvement of actual estimates, soil-atmospheric CO2, CH4, and N2O fluxes were measured in three successional subtropical forests at the Dinghushan Nature Reserve (hereafter referred to as DNR) in southern China. Soils in DNR forests behaved as N2O sources and CH4 sinks. Annual mean CO2, N2O, and CH4 fluxes (mean ?? SD) were 7.7 ?? 4.6MgCO2-Cha-1 yr-1, 3.2 ?? 1.2 kg N2ONha-1 yr-1, and 3.4 ?? 0.9 kgCH4-Cha-1 yr-1, respectively. The climate was warm and wet from April through September 2003 (the hot-humid season) and became cool and dry from October 2003 through March 2004 (the cool-dry season). The seasonality of soil CO2 emission coincided with the seasonal climate pattern, with high CO2 emission rates in the hot-humid season and low rates in the cool-dry season. In contrast, seasonal patterns of CH4 and N2O fluxes were not clear, although higher CH4 uptake rates were often observed in the cool-dry season and higher N2O emission rates were often observed in the hot-humid season. GHG fluxes measured at these three sites showed a clear increasing trend with the progressive succession. If this trend is representative at the regional scale, CO2 and N2O emissions and CH4 uptake in southern China may increase in the future in light of the projected change in forest age structure. Removal of surface litter reduced soil CO2 effluxes by 17-44% in the three forests but had no significant effect on CH4 absorption and N2O emission rates. This suggests that microbial CH4 uptake and N2O production was mainly related to the mineral soil rather than in the surface litter layer. ?? 2006 Blackwell Publishing Ltd.

  5. The European land and inland water CO2, CO, CH4 and N2O balance between 2001 and 2005

    Directory of Open Access Journals (Sweden)

    R. Thompson

    2012-08-01

    Full Text Available Globally, terrestrial ecosystems have absorbed about 30% of anthropogenic greenhouse gas emissions over the period 2000–2007 and inter-hemispheric gradients indicate that a significant fraction of terrestrial carbon sequestration must be north of the Equator. We present a compilation of the CO2, CO, CH4 and N2O balances of Europe following a dual constraint approach in which (1 a land-based balance derived mainly from ecosystem carbon inventories and (2 a land-based balance derived from flux measurements are compared to (3 the atmospheric data-based balance derived from inversions constrained by measurements of atmospheric GHG (greenhouse gas concentrations. Good agreement between the GHG balances based on fluxes (1294 ± 545 Tg C in CO2-eq yr−1, inventories (1299 ± 200 Tg C in CO2-eq yr−1 and inversions (1210 ± 405 Tg C in CO2-eq yr−1 increases our confidence that the processes underlying the European GHG budget are well understood and reasonably sampled. However, the uncertainty remains large and largely lacks formal estimates. Given that European net land to atmosphere exchanges are determined by a few dominant fluxes, the uncertainty of these key components needs to be formally estimated before efforts could be made to reduce the overall uncertainty. The net land-to-atmosphere flux is a net source for CO2, CO, CH4 and N2O, because the anthropogenic emissions by far exceed the biogenic sink strength. The dual-constraint approach confirmed that the European biogenic sink removes as much as 205 ± 72 Tg C yr−1 from fossil fuel burning from the atmosphere. However, This C is being sequestered in both terrestrial and inland aquatic ecosystems. If the C-cost for ecosystem management is taken into account, the net uptake of ecosystems is estimated to decrease by 45% but still indicates substantial C-sequestration. However, when the balance is extended from CO2 towards the main GHGs, C-uptake by terrestrial and aquatic ecosystems is

  6. Emissions of CO2, CO, NOx, HC, PM, HFC-134a, N2O and CH4 from the global light duty vehicle fleet

    Directory of Open Access Journals (Sweden)

    Timothy J. Wallington

    2008-04-01

    Full Text Available Vehicles emit carbon dioxide (CO2, carbon monoxide (CO, nitrogen oxides (NOx, hydrocarbons (HC, particulate matter (PM, hydrofluorocarbon 134a (HFC-134a, methane (CH4, and nitrous oxide (N2O. An understanding of these emissions is needed in discussions of climate change and local air pollution issues. To facilitate such discussions an overview of past, present, and likely future emissions from light duty vehicles is presented. Emission control technologies have reduced the emissions of CO, VOCs, PM, HFC-134a, CH4, and N2O from modern vehicles to very low levels.

  7. Cost-effectiveness analysis of farmers' rice straw management practices considering CH4 and N2O emissions.

    Science.gov (United States)

    Launio, Cheryll C; Asis, Constancio A; Manalili, Rowena G; Javier, Evelyn F

    2016-12-01

    This study assessed the environmental consequences of burning and other rice straw management practices in terms of non-CO2 greenhouse gas (GHG) emissions, and evaluated the cost-effectiveness of selected rice straw management alternatives. On a per-hectare basis and considering a time horizon of five years, incorporating stubble more than 30 days before crop establishment, and incorporating composted rice straw in the field yielded the lowest cumulative CH4 and N2O emissions. Considering the associated costs and secondary benefits, the most cost-effective option for farmers is to incorporate stubble and straw in the soil more than 30 days before crop establishment. Rapid straw composting and incorporation of rice straw compost entails much higher additional cost but it also significantly mitigates GHG emission, hence it is the next most cost-effective option. Incorporating rice stubble and straw less than a month before crop establishment and removing rice straw for use as animal feed, on the other hand, appear to result in a net increase in ton CO2-eq given the assumed time horizon. The results underscore the impacts on the environment of small changes in straw management practices entailing minimal costs. Cost-effectiveness analysis considering rice straw for power generation and bio ethanol production is recommended. Further study on water management and tillage practice as mitigation options is recommended for a broader perspective useful for farmers, policy-makers, and other rice stakeholders.

  8. Fluxes of CO2, CH4 and N2O at two European beech forests: linking soil gas production profiles with soil and stem fluxes

    Science.gov (United States)

    Maier, Martin; Machacova, Katerina; Halaburt, Ellen; Haddad, Sally; Urban, Otmar; Lang, Friederike

    2016-04-01

    Soil and plant surfaces are known to exchange greenhouse gases with the atmosphere. Some gases like nitrous oxide (N2O) and methane (CH4) can be produced and re-consumed in different soil depths and soil compartments, so that elevated concentrations of CH4 or N2O in the soil do not necessarily mean a net efflux from the soil into the atmosphere. Soil aeration, and thus the oxygen status can underlay a large spatial variability within the soil on the plot and profile scale, but also within soil aggregates. Thus, conditions suitable for production and consumption of CH4 and N2O can vary on different scales in the soil. Plant surfaces can also emit or take up CH4 and N2O, and these fluxes can significantly contribute to the net ecosystem exchange. Since roots usually have large intercellular spaces or aerenchyma they may represent preferential transport ways for soil gases, linking possibly elevated soil gas concentrations in the subsoil in a "shortcut" to the atmosphere. We tested the hypothesis that the spatial variability of the soil-atmosphere fluxes of CO2, CH4 and N2O is caused by the heterogeneity in soil properties. Therefore, we measured soil-atmosphere gas fluxes, soil gas concentrations and soil diffusivity profiles and did a small scale field assessment of soil profiles on the measurments plots. We further tried to link vertical profiles of soil gas concentrations and diffusivity to derive the production and consumption profiles, and to link these profiles to the stem-atmosphere flux rates of individual trees. Measurements were conducted in two mountain beech forests with different geographical and climatic conditions (White Carpathians, Czech Republic; Black Forest, Germany). Gas fluxes at stem and soil levels were measured simultaneously using static chamber systems and chromatographic and continuous laser analyses. Monitoring simultaneously vertical soil gas profiles allowed to assess the within-soil gas fluxes, and thus to localize the production and

  9. Response of CH4 and N2O emissions and wheat yields to tillage method changes in the North China plain.

    Directory of Open Access Journals (Sweden)

    Shenzhong Tian

    Full Text Available The objective of this study was to quantify soil methane (CH(4 and nitrous oxide (N(2O emissions when converting from minimum and no-tillage systems to subsoiling (tilled soil to a depth of 40 cm to 45 cm in the North China Plain. The relationships between CH(4 and N(2O flux and soil temperature, moisture, NH(4 (+-N, organic carbon (SOC and pH were investigated over 18 months using a split-plot design. The soil absorption of CH(4 appeared to increase after conversion from no-tillage (NT to subsoiling (NTS, from harrow tillage (HT to subsoiling (HTS and from rotary tillage (RT to subsoiling (RTS. N(2O emissions also increased after conversion. Furthermore, after conversion to subsoiling, the combined global warming potential (GWP of CH(4 and N(2O increased by approximately 0.05 kg CO(2 ha(-1 for HTS, 0.02 kg CO(2 ha(-1 for RTS and 0.23 kg CO(2 ha(-1 for NTS. Soil temperature, moisture, SOC, NH(4 (+-N and pH also changed after conversion to subsoiling. These changes were correlated with CH(4 uptake and N(2O emissions. However, there was no significant correlation between N(2O emissions and soil temperature in this study. The grain yields of wheat improved after conversion to subsoiling. Under HTS, RTS and NTS, the average grain yield was elevated by approximately 42.5%, 27.8% and 60.3% respectively. Our findings indicate that RTS and HTS would be ideal rotation tillage systems to balance GWP decreases and grain yield improvements in the North China Plain region.

  10. Responses of CO(2), N(2)O and CH(4) fluxes between atmosphere and forest soil to changes in multiple environmental conditions.

    Science.gov (United States)

    Yan, Junhua; Zhang, Wei; Wang, Keya; Qin, Fen; Wang, Wantong; Dai, Huitang; Li, Peixue

    2014-01-01

    To investigate the effects of multiple environmental conditions on greenhouse gas (CO2 , N2 O, CH4 ) fluxes, we transferred three soil monoliths from Masson pine forest (PF) or coniferous and broadleaved mixed forest (MF) at Jigongshan to corresponding forest type at Dinghushan. Greenhouse gas fluxes at the in situ (Jigongshan), transported and ambient (Dinghushan) soil monoliths were measured using static chambers. When the transported soil monoliths experienced the external environmental factors (temperature, precipitation and nitrogen deposition) at Dinghushan, its annual soil CO2 emissions were 54% in PF and 60% in MF higher than those from the respective in situ treatment. Annual soil N2 O emissions were 45% in PF and 44% in MF higher than those from the respective in situ treatment. There were no significant differences in annual soil CO2 or N2 O emissions between the transported and ambient treatments. However, annual CH4 uptake by the transported soil monoliths in PF or MF was not significantly different from that at the respective in situ treatment, and was significantly lower than that at the respective ambient treatment. Therefore, external environmental factors were the major drivers of soil CO2 and N2 O emissions, while soil was the dominant controller of soil CH4 uptake. We further tested the results by developing simple empirical models using the observed fluxes of CO2 and N2 O from the in situ treatment and found that the empirical models can explain about 90% for CO2 and 40% for N2 O of the observed variations at the transported treatment. Results from this study suggest that the different responses of soil CO2 , N2 O, CH4 fluxes to changes in multiple environmental conditions need to be considered in global change study.

  11. Emissions of CH4 and N2O under different tillage systems from double-cropped paddy fields in Southern China.

    Science.gov (United States)

    Zhang, Hai-Lin; Bai, Xiao-Lin; Xue, Jian-Fu; Chen, Zhong-Du; Tang, Hai-Ming; Chen, Fu

    2013-01-01

    Understanding greenhouse gases (GHG) emissions is becoming increasingly important with the climate change. Most previous studies have focused on the assessment of soil organic carbon (SOC) sequestration potential and GHG emissions from agriculture. However, specific experiments assessing tillage impacts on GHG emission from double-cropped paddy fields in Southern China are relatively scarce. Therefore, the objective of this study was to assess the effects of tillage systems on methane (CH4) and nitrous oxide (N2O) emission in a double rice (Oryza sativa L.) cropping system. The experiment was established in 2005 in Hunan Province, China. Three tillage treatments were laid out in a randomized complete block design: conventional tillage (CT), rotary tillage (RT) and no-till (NT). Fluxes of CH4 from different tillage treatments followed a similar trend during the two years, with a single peak emission for the early rice season and a double peak emission for the late rice season. Compared with other treatments, NT significantly reduced CH4 emission among the rice growing seasons (P<0.05). However, much higher variations in N2O emission were observed across the rice growing seasons due to the vulnerability of N2O to external influences. The amount of CH4 emission in paddy fields was much higher relative to N2O emission. Conversion of CT to NT significantly reduced the cumulative CH4 emission for both rice seasons compared with other treatments (P<0.05). The mean value of global warming potentials (GWPs) of CH4 and N2O emissions over 100 years was in the order of NT

  12. Mitigating effects of ex situ application of rice straw on CH4 and N2O emissions from paddy-upland coexisting system

    Science.gov (United States)

    Wang, Wei; Wu, Xiaohong; Chen, Anlei; Xie, Xiaoli; Wang, Yunqiu; Yin, Chunmei

    2016-11-01

    The in situ application of rice straw enhances CH4 emissions by a large margin. The ex situ application of rice straw in uplands, however, may mitigate total global warming potential (GWP) of CH4 and N2O emissions from paddy-upland coexisting systems. To evaluate the efficiency of this practice, two field trials were conducted in rice-rice-fallow and maize-rape cropping systems, respectively. Year-round measurements of CH4 and N2O emissions were conducted to evaluate the system-scaled GWP. The results showed that CH4 accounted for more than 98% of GWP in paddy. Straw removal from paddy decreased 44.7% (302.1 kg ha‑1 yr‑1) of CH4 emissions and 51.2% (0.31 kg ha‑1 yr‑1) of N2O emissions, thus decreased 44.8% (7693 kg CO2-eqv ha‑1 yr‑1) of annual GWP. N2O accounted for almost 100% of GWP in upland. Straw application in upland had insignificant effects on CH4 and N2O emissions, which increased GWP only by 91 kg CO2-eqv ha‑1 yr‑1. So, the transfer of straw from paddy to upland could decrease GWP by 7602 kg CO2-eqv ha‑1 yr‑1. Moreover, straw retention during late rice season contributed to 88.2% of annual GWP increment. It is recommended to transfer early rice straw to upland considering GWP mitigation, nutrient recycling and labor cost.

  13. A single gas chromatograph for accurate atmospheric mixing ratio measurements of CO2, CH4, N2O, SF6 and CO

    NARCIS (Netherlands)

    van der Laan, S.; Neubert, R. E. M.; Meijer, H. A. J.; Simpson, W.R.

    2009-01-01

    We present an adapted gas chromatograph capable of measuring simultaneously and semi-continuously the atmospheric mixing ratios of the greenhouse gases CO2, CH4, N2O and SF6 and the trace gas CO with high precision and long-term stability. The novelty of our design is that all species are measured

  14. A single gas chromatograph for accurate atmospheric mixing ratio measurements of CO2, CH4, N2O, SF6 and CO

    NARCIS (Netherlands)

    van der Laan, S.; Neubert, R. E. M.; Meijer, H. A. J.; Simpson, W.R.

    2009-01-01

    We present an adapted gas chromatograph capable of measuring simultaneously and semi-continuously the atmospheric mixing ratios of the greenhouse gases CO2, CH4, N2O and SF6 and the trace gas CO with high precision and long-term stability. The novelty of our design is that all species are measured w

  15. Effects of phosphorus addition on nitrogen cycle and fluxes of N2O and CH4 in tropical tree plantation soils in Thailand

    Directory of Open Access Journals (Sweden)

    Taiki Mori

    2017-04-01

    Full Text Available An incubation experiment was conducted to test the effects of phosphorus (P addition on nitrous oxide (N2O emissions and methane (CH4 uptakes, using tropical tree plantation soils in Thailand. Soil samples were taken from five forest stands—Acacia auriculiformis, Acacia mangium, Eucalyptus camaldulensis, Hopea odorata, and Xylia xylocarpa—and incubated at 80% water holding capacity. P addition stimulated N2O emissions only in Xylia xylocarpa soils. Since P addition tended to increase net ammonification rates in Xylia xylocarpa soils, the stimulated N2O emissions were suggested to be due to the stimulated nitrogen (N cycle by P addition and the higher N supply for nitrification and denitrification. In other soils, P addition had no effects on N2O emissions or soil N properties, except that P addition tended to increase the soil microbial biomass N in Acacia auriculiformis soils. No effects of P addition were observed on CH4 uptakes in any soil. It is suggested that P addition on N2O and CH4 fluxes at the study site were not significant, at least under laboratory conditions.

  16. Drainage and tillage practices in the winter fallow season mitigate CH4 and N2O emissions from a double-rice field in China

    Science.gov (United States)

    Zhang, Guangbin; Yu, Haiyang; Fan, Xianfang; Yang, Yuting; Ma, Jing; Xu, Hua

    2016-09-01

    Traditional land management (no tillage, no drainage, NTND) during the winter fallow season results in substantial CH4 and N2O emissions from double-rice fields in China. A field experiment was conducted to investigate the effects of drainage and tillage during the winter fallow season on CH4 and N2O emissions and to develop mitigation options. The experiment had four treatments: NTND, NTD (drainage but no tillage), TND (tillage but no drainage), and TD (both drainage and tillage). The study was conducted from 2010 to 2014 in a Chinese double-rice field. During winter, total precipitation and mean daily temperature significantly affected CH4 emission. Compared to NTND, drainage and tillage decreased annual CH4 emissions in early- and late-rice seasons by 54 and 33 kg CH4 ha-1 yr-1, respectively. Drainage and tillage increased N2O emissions in the winter fallow season but reduced it in early- and late-rice seasons, resulting in no annual change in N2O emission. Global warming potentials of CH4 and N2O emissions were decreased by 1.49 and 0.92 t CO2 eq. ha-1 yr-1, respectively, and were reduced more by combining drainage with tillage, providing a mitigation potential of 1.96 t CO2 eq. ha-1 yr-1. A low total C content and high C / N ratio in rice residues showed that tillage in the winter fallow season reduced CH4 and N2O emissions in both early- and late-rice seasons. Drainage and tillage significantly decreased the abundance of methanogens in paddy soil, and this may explain the decrease of CH4 emissions. Greenhouse gas intensity was significantly decreased by drainage and tillage separately, and the reduction was greater by combining drainage with tillage, resulting in a reduction of 0.17 t CO2 eq. t-1. The results indicate that drainage combined with tillage during the winter fallow season is an effective strategy for mitigating greenhouse gas releases from double-rice fields.

  17. Geographic Inventory Framework (GiF) for estimating N2O and CH4 emissions from agriculture in the province of Alberta, Canada

    Science.gov (United States)

    Dimitrov, D. D.; Wang, J.

    2016-12-01

    A Geographic Information Framework (GiF) has been created to estimate and map agricultural N2O and CH4 emissions of the province of Alberta, Canada. The GiF consists of a modelling component, a GIS component, and application software to communicate between the model, database and census data. For compatibility, GiF follows the IPCC Tier 1 method and contains census data for animal populations, crop areas, and farms for the main IPCC animal and plant types (dairy cows, cattle cows, pigs, sheep, poultry, other animals, grasses, legumes, other crops), and estimated N2O and CH4 emissions from manure management, enteric fermentation, direct soil emissions (with applied manure, synthetic fertilizer, crop residue degradation, biological fixation) and indirect soil emissions (with atmospheric deposition and leaching). Methane emissions from enteric fermentation (609.24 Gg) prevailed over those from manure (44.99 Gg), and nitrous oxide emission from manure (22.01 Gg) prevailed over those from soil (17.73 Gg), with cattle cows emitting most N2O and CH4, followed by plant N2O emissions, and pigs and dairy cows CH4 emissions. The GIS maps showed discernible pattern of N2O and CH4 emissions increasing from North and West to the central Alberta and then slightly declining to South and East, which could be useful to address various mitigation strategies. The framework allows easy replacement of Tier 1 emission factors by Tire 2 or 3 ones from process-based models. Future applying of the latter will allow accounting for CO2 source/sink strength of agricultural ecosystems, hence their complete GHG balance affected by soil, water, and climate.

  18. 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.

  19. N2O and CH4 emissions from a fallow-wheat rotation with low N input in conservation and conventional tillage under a Mediterranean agroecosystem.

    Science.gov (United States)

    Tellez-Rio, Angela; García-Marco, Sonia; Navas, Mariela; López-Solanilla, Emilia; Tenorio, Jose Luis; Vallejo, Antonio

    2015-03-01

    Conservation agriculture that includes no tillage (NT) or minimum tillage (MT) and crop rotation is an effective practice to increase soil organic matter in Mediterranean semiarid agrosystems. But the impact of these agricultural practices on greenhouse gases (GHGs), such as nitrous oxide (N2O) and methane (CH4), is variable depending mainly on soil structure and short/long-term tillage. The main objective of this study was to assess the long-term effect of three tillage systems (NT, MT and conventional tillage (CT)) and land-covers (fallow/wheat) on the emissions of N2O and CH4 in a low N input agricultural system during one year. This was achieved by measuring crop yields, soil mineral N and dissolved organic C contents, and fluxes of N2O and CH4. Total cumulative N2O emissions were not significantly different (P>0.05) among the tillage systems or between fallow and wheat. The only difference was produced in spring, when N2O emissions were significantly higher (Ptillage systems, in spite of the higher DOC content maintained in the topsoil of NT. This could be due to the similar denitrifier densities, targeted by nirK copy numbers at that time. Cumulative CH4 fluxes resulted in small net uptake for all treatments, and no significant differences were found among tillage systems or between fallow and wheat land-covers. These results suggest that under a coarse-textured soil in low N agricultural systems, the impact of tillage on GHG is very low and that the fallow cycle within a crop rotation is not a useful strategy to reduce GHG emissions.

  20. Application of herbicides is likely to reduce greenhouse gas (N2O and CH4) emissions from rice-wheat cropping systems

    Science.gov (United States)

    Jiang, Jingyan; Chen, Linmei; Sun, Qing; Sang, Mengmeng; Huang, Yao

    2015-04-01

    Herbicides have been widely used to control weeds in croplands; however, their effects on greenhouse gas emissions remain unclear. The effects of three wheat herbicides (acetochlor, AC; tribenuron-methyl, TBM; fenoxaprop-p-ethyl, FE) and two rice herbicides (butachlor, BC; bensulfuron-methyl, BSM) on N2O and CH4 emissions were investigated in this study. In the wheat growing season, applications of AC and FE + TBM significantly reduced N2O emissions by 31% compared with no herbicide use (p = 0.001). In the rice growing season, the application of BC significantly reduced CH4 emissions by 58% (p = 0.022), and BSM significantly reduced N2O emissions by 27% (p = 0.040); however, no significant difference among treatments with regard to the aggregate emissions of N2O and CH4 in the CO2 equivalent for the 100-year horizon was observed (p > 0.05). Relative to control plots, which were not treated with herbicides, the combined application of the herbicides FE and TBM in the wheat season led to a significant decrease in greenhouse gas intensity (GHGI) by ∼41% (p = 0.002), and the application of BC together with BSM reduced GHGI by 22% in the rice season, although this reduction was not statistically significant (p = 0.158). Further investigation suggested that the inhibitory effect of herbicides on N2O emissions in the wheat field could be ascribed to low soil ammonium nitrogen and less abundance of denitrifying bacteria. The inhibitory effects of separate applications of BC on CH4 emissions in rice fields, in contrast, were linked to high soil nitrate nitrogen and urease activity.

  1. Shipborne solar absorption measurements of CO2, CH4, N2O and CO and comparison with SCIAMACHY WFM-DOAS retrievals

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    V. Velazco

    2005-02-01

    Full Text Available CO, CH4, N2O and CO2 were retrieved from high resolution solar absorption spectra obtained during a ship cruise from Capetown to Bremerhaven in January/February 2003 by Fourier Transform Infrared (FTIR spectroscopy. Precisions of better than 0.5% for the column averaged volume mixing ratios (VMR of CH4 and CO2 are achieved using of O2 as a reference gas. Shipborne FTIR-measurements of CO and data from SCIAMACHY/ENVISAT retrieved by the Weighting Function Modified Differential Optical Absorption Spectroscopy (WFM-DOAS retrieval algorithm show qualitatively the same latitudinal variations. WFM-DOAS data of CH4, N2O and CO2 measured over sea exhibit a great spread. The spread is significantly reduced for satellite measurements over land and a reasonable agreement can be obtained if the shipborne data is compared with the closest SCIAMACHY measurements over land. The number of comparisons is too small to draw conclusions. However, by including only WFM-DOAS data with small errors the shipborne and WFM-DOAS data compare within 5% for CH4 and CO2 and within 30% for N2O.

  2. Shipborne solar absorption measurements of CO2, CH4, N2O and CO and comparison with SCIAMACHY WFM-DOAS retrievals

    Directory of Open Access Journals (Sweden)

    T. Warneke

    2005-01-01

    Full Text Available CO, CH4, N2O and CO2 were retrieved from high resolution solar absorption spectra obtained during a ship cruise from Capetown to Bremerhaven in January/February 2003 by Fourier Transform Infrared (FTIR spectroscopy. Precisions of better than 0.5% for the column averaged volume mixing ratios (VMR of CH4 and CO2 are achieved using of O2 as a reference gas. Shipborne FTIR-measurements of CO and data from SCIAMACHY/ENVISAT retrieved by the Weighting Function Modified Differential Optical Absorption Spectroscopy (WFM-DOAS retrieval algorithm show qualitatively the same latitudinal variations. WFM-DOAS data of CH4, N2O and CO2 measured over sea exhibit a great spread. The spread is significantly reduced for satellite measurements over land and a reasonable agreement can be obtained if the shipborne data are compared with the closest SCIAMACHY measurements over land. The number of comparisons is too small to draw conclusions. However, by including only WFM-DOAS data with small errors the shipborne and WFM-DOAS data compare within 5% for CH4 and CO2 and within 30% for N2O.

  3. Shipborne solar absorption measurements of CO2, CH4, N2O and CO and comparison with SCIAMACHY WFM-DOAS retrievals

    Science.gov (United States)

    Warneke, T.; de Beek, R.; Buchwitz, M.; Notholt, J.; Schulz, A.; Velazco, V.; Schrems, O.

    2005-08-01

    CO, CH4, N2O and CO2 were retrieved from high resolution solar absorption spectra obtained during a ship cruise from Capetown to Bremerhaven in January/February 2003 by Fourier Transform Infrared (FTIR) spectroscopy. Precisions of better than 0.5% for the column averaged volume mixing ratios (VMR) of CH4 and CO2 are achieved using of O2 as a reference gas. Shipborne FTIR-measurements of CO and data from SCIAMACHY/ENVISAT retrieved by the Weighting Function Modified Differential Optical Absorption Spectroscopy (WFM-DOAS) retrieval algorithm show qualitatively the same latitudinal variations. WFM-DOAS data of CH4, N2O and CO2 measured over sea exhibit a great spread. The spread is significantly reduced for satellite measurements over land and a reasonable agreement can be obtained if the shipborne data are compared with the closest SCIAMACHY measurements over land. The number of comparisons is too small to draw conclusions. However, by including only WFM-DOAS data with small errors the shipborne and WFM-DOAS data compare within 5% for CH4 and CO2 and within 30% for N2O.

  4. Effects of simulated nitrogen deposition on N2O and CH4 fluxes of soil in forest belt%氮沉降对林带土壤N2O和CH4通量的影响

    Institute of Scientific and Technical Information of China (English)

    胡正华; 张寒; 陈书涛; 李琪; 李涵茂; 申双和

    2011-01-01

    To investigate the effects of elevated nitrogen deposition on forest soil N2O and CH4 fluxes, a simulated nitrogen deposition field experiment was conducted in forest belt from April 2008 to October 2009. Nitrogen treatments included the control (no N addition, CK), low-N [50kgN/(hm2·a), TL], medium-N [100kgN/(hm2·a), TM], and high-N [150kg N/(hm2·a), TH]. N2O and CH4 fluxes were measured by a static chamber-gas chromatograph method. Nitrogen deposition did not change the seasonal and daily variation patterns of soil N2O and CH4 fluxes. Compared to the control,TL, TM and TH treatments had no significant effects on annual average and daily average fluxes of N2O and CH4 in soil.Short-term nitrogen deposition did not alter N2O emission fluxes and CHh absorb fluxes of soil in forest belt.%于2008年4月~2009年10月在龙王山对林带土壤进行模拟氮沉降试验,采用静态箱-气相色谱法测定土壤N2O和CH4通量,研究氮沉降增加对土壤N2O和CH4排放(吸收)的影响.结果表明,短期内,氮沉降没改变土壤N2O和CH4通量的季节性变化规律和日变化规律.与对照(CK)相比,短期的低氮[50kg N/(hm2·a),TL]、中氮[100kgN/(hm2·a),TM]和高氮[150kgN/(hm2·a),TH]处理对土壤的N2O和CH4年平均通量和日平均通量都没有显著影响.

  5. Responses of CH(4), CO(2) and N(2)O fluxes to increasing nitrogen deposition in alpine grassland of the Tianshan Mountains.

    Science.gov (United States)

    Li, Kaihui; Gong, Yanming; Song, Wei; He, Guixiang; Hu, Yukun; Tian, Changyan; Liu, Xuejun

    2012-06-01

    To assess the effects of nitrogen (N) deposition on greenhouse gas (GHG) fluxes in alpine grassland of the Tianshan Mountains in central Asia, CH(4), CO(2) and N(2)O fluxes were measured from June 2010 to May 2011. Nitrogen deposition tended to significantly increase CH(4) uptake, CO(2) and N(2)O emissions at sites receiving N addition compared with those at site without N addition during the growing season, but no significant differences were found for all sites outside the growing season. Air temperature, soil temperature and water content were the important factors that influence CO(2) and N(2)O emissions at year-round scale, indicating that increased temperature and precipitation in the future will exert greater impacts on CO(2) and N(2)O emissions in the alpine grassland. In addition, plant coverage in July was also positively correlated with CO(2) and N(2)O emissions under elevated N deposition rates. The present study will deepen our understanding of N deposition impacts on GHG balance in the alpine grassland ecosystem, and help us assess the global N effects, parameterize Earth System models and inform decision makers. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Retrieval of tropospheric column-averaged CH4 mole fraction by solar absorption FTIR-spectrometry using N2O as a proxy

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    Z. Wang

    2014-02-01

    Full Text Available Tropospheric column-averaged CH4 mole fractions were derived from ground-based absorption columns measurements. The method used stratospheric N2O columns to correct for the stratospheric contribution to the CH4 total column. The method was applied to four TCCON sites covering locations from the Northern Arctic to the tropics. It performs well for all sites. The derived tropospheric CH4 concentrations were compared with profiles measured by aircraft at three sites. The results indicate an inter-site consistency within 6 ppb (~ 0.3%. With aircraft profiles up to 3 km, the seasonal behavior of the derived tropospheric CH4 concentration was also checked. It reveals a difference of 20 ppb around. The mean relative uncertainty of the four sites is 0.23%. Comparing with the method using HF the proposed method shows a smaller relative uncertainty and less H2O dependence.

  7. Effects of the herbicides prosulfuron and metolachlor on fluxes of CO2, N2O, and CH4 in a fertilized Colorado grassland soil

    Science.gov (United States)

    Kinney, C.A.; Mosier, A.R.; Ferrer, I.; Furlong, E.T.; Mandernack, K.W.

    2004-01-01

    The effect that pesticides have on trace gas production and consumption in agricultural soils is often overlooked. Independent field and laboratory experiments were used to measure the effects that the commonly used herbicides prosulfuron and metolachlor have on trace gas fluxes (CO2, N2O, and CH4) from fertilized soil of the Colorado shortgrass steppe. Separate sample plots (1 m2) on tilled and no-till soil at the sites included the following treatments: 1) a control without fertilizer or herbicide, 2) a fertilized (NH4NO3 equivalent to 244 kg ha-1) control without herbicide, 3) and fertilized plots amended with an herbicide (prosulfuron equivalent to 0.46 kg ha-1 57% by weight active ingredient or metolachlor equivalent to 5.7 L ha-1, 82.4% by weight active ingredient). During an initial study of one year duration, measurement of gas exchange revealed that prosulfuron-amendment stimulated N2O emissions and CH4 consumption by as much as 1600% and 1300% during a single measurement, respectively. During a second set of flux measurements beginning in August 2001, more frequent weekly measurements were made during a twelve week period. From this second study an increased N2O efflux and CH4 uptake occurred after a 7-week lag period that persisted for about 5 weeks. These changes in gas flux amounted to an overall increase of 41% and 30% for N2O emission and CH4 consumption, respectively. The co-occurrence of stimulated N2O and CH4 fluxes suggests a similar cause that is related to prosulfuron degradation. Evidence suggested that prosulfuron degradation stimulated microbial activity responsible for trace gas flux. Ultimately, prosulfuron-amendment led to an ???50% reduction in the global warming potential from N2O and CH4 fluxes at this field site, which is equivalent to a reduction of the global warming potential of 0.18 mols CO2 m-2 d-1 from these gases. Metolachlor application did not significantly affect the trace gas fluxes measured. These results demonstrate the

  8. Annual emissions of CH4 and N2O, and ecosystem respiration, from eight organic soils in Western Denmark managed by agriculture

    Science.gov (United States)

    Petersen, S. O.; Hoffmann, C. C.; Schäfer, C.-M.; Blicher-Mathiesen, G.; Elsgaard, L.; Kristensen, K.; Larsen, S. E.; Torp, S. B.; Greve, M. H.

    2012-01-01

    The use of organic soils by agriculture involves drainage and tillage, and the resulting increase in C and N turnover can significantly affect their greenhouse gas balance. This study estimated annual fluxes of CH4 and N2O, and ecosystem respiration (Reco), from eight organic soils managed by agriculture. The sites were located in three regions representing different landscape types and climatic conditions, and three land use categories were covered (arable crops, AR, grass in rotation, RG, and permanent grass, PG). The normal management at each site was followed, except that no N inputs occurred during the monitoring period from August 2008 to October 2009. The stratified sampling strategy further included six sampling points in three blocks at each site. Environmental variables (precipitation, PAR, air and soil temperature, soil moisture, groundwater level) were monitored continuously and during sampling campaigns, where also groundwater samples were taken for analysis. Gaseous fluxes were monitored on a three-weekly basis, giving 51, 49 and 38 field campaigns for land use categories AR, PG and RG, respectively. Climatic conditions in each region during monitoring were representative as compared to 20-yr averages. Peat layers were shallow, typically 0.5 to 1 m, and with a pH of 4 to 5. At six sites annual emissions of N2O were in the range 3 to 24 kg N2O-N ha-1, but at two arable sites (spring barley, potato) net emissions of 38 and 61 kg N2O-N ha-1 were recorded. The two high-emitting sites were characterized by fluctuating groundwater, low soil pH and elevated groundwater SO42- concentrations. Annual fluxes of CH4 were generally small, as expected, ranging from 2 to 4 kg CH4 ha-1. However, two permanent grasslands had tussocks of Juncus effusus L. (soft rush) in sampling points that were consistent sources of CH4 throughout the year. Emission factors for organic soils in rotation and with permanent grass, respectively, were estimated to be 0.011 and 0.47 g m-2

  9. Assessing the performance of the photo-acoustic infrared gas monitor for measuring CO(2), N(2)O, and CH(4) fluxes in two major cereal rotations.

    Science.gov (United States)

    Tirol-Padre, Agnes; Rai, Munmun; Gathala, Mahesh; Sharma, Sheetal; Kumar, Virender; Sharma, Parbodh C; Sharma, Dinesh K; Wassmann, Reiner; Ladha, Jagdish

    2014-01-01

    Rapid, precise, and globally comparable methods for monitoring greenhouse gas (GHG) fluxes are required for accurate GHG inventories from different cropping systems and management practices. Manual gas sampling followed by gas chromatography (GC) is widely used for measuring GHG fluxes in agricultural fields, but is laborious and time-consuming. The photo-acoustic infrared gas monitoring system (PAS) with on-line gas sampling is an attractive option, although it has not been evaluated for measuring GHG fluxes in cereals in general and rice in particular. We compared N2 O, CO2 , and CH4 fluxes measured by GC and PAS from agricultural fields under the rice-wheat and maize-wheat systems during the wheat (winter), and maize/rice (monsoon) seasons in Haryana, India. All the PAS readings were corrected for baseline drifts over time and PAS-CH4 (PCH4 ) readings in flooded rice were corrected for water vapor interferences. The PCH4 readings in ambient air increased by 2.3 ppm for every 1000 mg cm(-3) increase in water vapor. The daily CO2 , N2 O, and CH4 fluxes measured by GC and PAS from the same chamber were not different in 93-98% of all the measurements made but the PAS exhibited greater precision for estimates of CO2 and N2 O fluxes in wheat and maize, and lower precision for CH4 flux in rice, than GC. The seasonal GC- and PAS-N2 O (PN2 O) fluxes in wheat and maize were not different but the PAS-CO2 (PCO2 ) flux in wheat was 14-39% higher than that of GC. In flooded rice, the seasonal PCH4 and PN2 O fluxes across N levels were higher than those of GC-CH4 and GC-N2 O fluxes by about 2- and 4fold, respectively. The PAS (i) proved to be a suitable alternative to GC for N2 O and CO2 flux measurements in wheat, and (ii) showed potential for obtaining accurate measurements of CH4 fluxes in flooded rice after making correction for changes in humidity.

  10. Annual emissions of CH4 and N2O, and ecosystem respiration, from eight organic soils in Western Denmark managed by agriculture

    Directory of Open Access Journals (Sweden)

    M. H. Greve

    2011-10-01

    Full Text Available The use of organic soils by agriculture involves drainage and tillage, and the resulting increase in C and N turnover can significantly affect their greenhouse gas balance. This study estimated annual fluxes of CH4 and N2O, and ecosystem respiration (Reco, from eight organic soils managed by agriculture. The sites were located in three regions representing different landscape types and climatic conditions, and three land use categories (arable crops, AR, grass in rotation, RG, and permanent grass, PG were covered. The normal management at each site was followed, except that no N inputs occurred during the monitoring period from August 2008 to October 2009. The stratified sampling strategy further included six sampling points in three blocks at each site. Environmental variables (precipitation, PAR, air and soil temperature, soil moisture, groundwater level were monitored continuously and during sampling campaigns, where also groundwater samples were taken for analysis. Gaseous fluxes were monitored on a three-weekly basis, giving 51, 49 and 38 field campaigns for land use categories AR, PG and RG, respectively. Climatic conditions in each region during monitoring were representative based on 20-yr averages. Peat layers were shallow, typically 0.5 to 1 m, and with a pH of 4–5. At six sites annual emissions of N2O were in the range 3 to 24 kg N2O-N ha−1, but at two arable sites (spring barley, potato net emissions of 38 and 61 kg N2O-N ha−1 were recorded. Both were characterized by fluctuating groundwater with elevated SO42− concentrations. Annual fluxes of CH4 were generally small, as expected, ranging from –2 to 4 kg CH4 ha−1. However, two permanent grasslands had tussocks of Juncus effusus (soft rush in sampling points that were consistent sources of CH4 throughout the year. Emission factors for organic soils in rotation and permanent grass, respectively, were estimated to be 0.011 and 0.47 g m−2 for CH4, and 2.5 and 0.5 g m−2

  11. [N2O and CH4 emission from Japan rice fields under different long-term fertilization patterns and its environmental impact].

    Science.gov (United States)

    Luo, Liang-guo; Kondo, Motohiko; Itoh, Sumio

    2010-12-01

    This study intended to investigate the greenhouse gases emission from Japan single cropping paddy fields after 75-year continuous application of ammonium sulfate, composted rice straw with soybean cake, and fresh clover, as well as the environmental impact of the emission. During this long period, field management remained constant in terms of rice cultivation density, irrigation, and equivalent net N fertilization. No significant differences were observed in N2O emission among the fertilization treatments, but the CH4 emission differed significantly between organic amendment and ammonium sulfate application, indicating that long-term organic fertilization didn' t increase N2O emission but promoted CH4 emission. The cumulative global warming potential (GWP) of the CH4 and NO2O from the paddy ecosystem was the greatest (310.7 g CO2e x m(-2)) under fresh clover application, followed by composted rice straw plus soybean cake addition (151 g CO2e x m(-2)), and the least (60.6 g CO2e x m(-2)) under ammonium sulfate application. This study showed that for paddy system, it was CH4 instead of N2O the major factor affecting global warming, and thereby, to control and reduce the CH4 emission from paddy system would be the core in mitigating greenhouse gases emission from paddy field. Long-term consecutive application of composted rice straw plus soybean cake could increase soil organic matter, improve soil fertility, promote rice high-yielding, and as well, mitigate CH4 emission, being the recommendable paddy rice production mode in practice.

  12. Ten years of CO2, CH4, CO and N2O fluxes over Western Europe inferred from atmospheric measurements at Mace Head, Ireland

    Directory of Open Access Journals (Sweden)

    S. G. Jennings

    2008-01-01

    Full Text Available We estimated CO2, CH4, CO and N2O emission fluxes over the British Isles and Western Europe using atmospheric radon observations and concentrations recorded at the Mace Head Atmospheric Research Station between 1996 and 2005. We classified hourly concentration data into either long-range European or regional sources from Ireland and UK, by using local wind speed data in conjunction with 222Rn and 212Pb threshold criteria. This leads to the selection of about 7% of the total data for both sectors. We then used continuous 222Rn measurements and assumptions on the surface emissions of 222Rn to deduce the unknown fluxes of CO2, CH4, CO and N2O. Our results have been compared to the UNFCCC, EMEP and EDGAR statistical inventories and to inversion results for CH4. For Western Europe, we found yearly mean fluxes of 4.1±1.5 106 kg CO2 km−2 yr−1 , 11.9±2.0 103 kg CH4 km−2 yr−1, 12.8±4.2 103 kg CO km−2 yr−1 and 520.2±129.2 kg N2O km−2 yr−1, respectively, for CO2, CH4, CO and N2O over the period 1996–2005. The method based upon 222Rn to infer emissions has many sources of systematic errors, in particular its poorly known and variable footprint, uncertainties in 222Rn soil fluxes and in atmospheric mixing of air masses with background air. However, these biases are likely to remain constant in the long-term, which makes the method quite efficient to detect trends in fluxes. Over the last ten years period, the decrease of the anthropogenic CH4, CO and N2O emissions in Europe estimated by inventories (respectively −30%, −35% and −23% is confirmed by the Mace Head data within 2%. Therefore, the 222Rn method provides an independent way of verification of changes in national emissions derived from inventories. Using European-wide estimates of the CO/CO2 emission ratio, we also found that it is possible to separate the fossil fuel CO2 emissions contribution from the one of total CO2 fluxes. The fossil fuel CO2 emissions and their trends

  13. Decadal variability of soil CO2, NO, N2O, and CH4 fluxes at the Höglwald Forest, Germany

    Directory of Open Access Journals (Sweden)

    K. Butterbach-Bahl

    2012-05-01

    Full Text Available Besides agricultural soils, temperate forest soils have been identified as significant sources of or sinks for important atmospheric trace gases (N2O, NO, CH4, and CO2. Although the number of studies for this ecosystem type increased more than tenfold during the last decade, studies covering an entire year and spanning more than 1–2 years remained scarce. This study reports the results of continuous measurements of soil-atmosphere C- and N-gas exchange with high temporal resolution carried out since 1994 at the Höglwald Forest spruce site, an experimental field station in Southern Germany. Annual soil N2O, NO and CO2 emissions and CH4 uptake (1994–2010 varied in a range of 0.2–3.0 kg N2O-N ha−1yr−1, 6.4–11.4 kg NO-N ha−1yr−1, 7.0–9.2 t CO2-C ha−1yr−1, and 0.9–3.5 kg CH4-C ha−1yr−1, respectively. The observed high fluxes of N-trace gases are most likely a consequence of high rates of atmospheric nitrogen deposition (>20 kg N ha−1yr−1 of NH3 and NOx to our site. For N2O, cumulative annual emissions were ≥ 0.8 kg N2O-N ha−1yr−1 in years with freeze-thaw events (5 out 14 of years. This shows that long-term, multi-year measurements are needed to obtain reliable estimates of N2O fluxes for a given ecosystem. Cumulative values of soil respiratory CO2 fluxes tended to be highest in years with prolonged freezing periods, i.e. years with below average annual mean soil temperatures and high N2O emissions (e.g. the years 1996 and 2006. Furthermore, based on our unique database on trace gas fluxes we analyzed if soil temperature, soil moisture measurements can be used to approximate trace gas fluxes at daily, weekly, monthly, or annual scale. Our analysis shows that simple-to-measure environmental drivers such as soil temperature or soil moisture are suitable to approximate fluxes of NO and CO2 at weekly and monthly resolution reasonably well (accounting for up to 59 % of the variance. However, for CH4 we so far failed

  14. CW EC-QCL-based sensor for simultaneous detection of H2O, HDO, N2O and CH4 using multi-pass absorption spectroscopy.

    Science.gov (United States)

    Yu, Yajun; Sanchez, Nancy P; Griffin, Robert J; Tittel, Frank K

    2016-05-16

    A sensor system based on a continuous wave, external-cavity quantum-cascade laser (CW EC-QCL) was demonstrated for simultaneous detection of atmospheric H2O, HDO, N2O and CH4 using a compact, dense pattern multi-pass gas cell with an effective path-length of 57.6 m. The EC-QCL with a mode-hop-free spectral range of 1225-1285 cm-1 operating at ~7.8 µm was scanned covering four neighboring absorption lines, for H2O at 1281.161 cm-1, HDO at 1281.455 cm-1, N2O at 1281.53 cm-1 and CH4 at 1281.61 cm-1. A first-harmonic-normalized wavelength modulation spectroscopy with second-harmonic detection (WMS-2f/1f) strategy was employed for data processing. An Allan-Werle deviation analysis indicated that minimum detection limits of 1.77 ppmv for H2O, 3.92 ppbv for HDO, 1.43 ppbv for N2O, and 2.2 ppbv for CH4 were achieved with integration times of 50-s, 50-s, 100-s and 129-s, respectively. Experimental measurements of ambient air are also reported.

  15. The development and evaluation of airborne in situ N2O and CH4 sampling using a Quantum Cascade Laser Absorption Spectrometer (QCLAS

    Directory of Open Access Journals (Sweden)

    J. R. Pitt

    2015-08-01

    Full Text Available Spectroscopic measurements of atmospheric N2O and CH4 mole fractions were made on board the FAAM (Facility for Airborne Atmospheric Measurements large Atmospheric Research Aircraft. We present details of the mid-IR Aerodyne Research Inc. Quantum Cascade Laser Absorption Spectrometer (QCLAS employed, including its configuration for airborne sampling, and evaluate its performance over 17 flights conducted during summer 2014. Two different methods of correcting for the influence of water vapour on the spectroscopic retrievals are compared and evaluated. A new in-flight calibration procedure to account for the observed sensitivity of the instrument to ambient pressure changes is described, and its impact on instrument performance is assessed. Test flight data linking this sensitivity to changes in cabin pressure is presented. Total 1σ uncertainties of 1.81 ppb for CH4 and 0.35 ppb for N2O are derived. We report a mean difference in 1 Hz CH4 mole fraction of 2.05 ppb (1σ = 5.85 ppb between in-flight measurements made using the QCLAS and simultaneous measurements using a previously characterised Los Gatos Research Fast Greenhouse Gas Analyser (FGGA. Finally, a potential case study for the estimation of a regional N2O flux using a mass balance technique is identified, and the method for calculating such an estimate is outlined.

  16. Exotic Spartina alterniflora invasion alters ecosystem-atmosphere exchange of CH4 and N2O and carbon sequestration in a coastal salt marsh in China.

    Science.gov (United States)

    Yuan, Junji; Ding, Weixin; Liu, Deyan; Kang, Hojeong; Freeman, Chris; Xiang, Jian; Lin, Yongxin

    2015-04-01

    Coastal salt marshes are sensitive to global climate change and may play an important role in mitigating global warming. To evaluate the impacts of Spartina alterniflora invasion on global warming potential (GWP) in Chinese coastal areas, we measured CH4 and N2O fluxes and soil organic carbon sequestration rates along a transect of coastal wetlands in Jiangsu province, China, including open water; bare tidal flat; and invasive S. alterniflora, native Suaeda salsa, and Phragmites australis marshes. Annual CH4 emissions were estimated as 2.81, 4.16, 4.88, 10.79, and 16.98 kg CH4 ha(-1) for open water, bare tidal flat, and P. australis, S. salsa, and S. alterniflora marshes, respectively, indicating that S. alterniflora invasion increased CH4 emissions by 57-505%. In contrast, negative N2O fluxes were found to be significantly and negatively correlated (P carbon sequestration rate of S. alterniflora marsh amounted to 3.16 Mg C ha(-1) yr(-1) in the top 100 cm soil profile, a value that was 2.63- to 8.78-fold higher than in native plant marshes. The estimated GWP was 1.78, -0.60, -4.09, and -1.14 Mg CO2 eq ha(-1) yr(-1) in open water, bare tidal flat, P. australis marsh and S. salsa marsh, respectively, but dropped to -11.30 Mg CO2 eq ha(-1) yr(-1) in S. alterniflora marsh. Our results indicate that although S. alterniflora invasion stimulates CH4 emissions, it can efficiently mitigate increases in atmospheric CO2 and N2O along the coast of China.

  17. Growing season CH4 and N2O fluxes from a subarctic landscape in northern Finland; from chamber to landscape scale

    Science.gov (United States)

    Dinsmore, Kerry J.; Drewer, Julia; Levy, Peter E.; George, Charles; Lohila, Annalea; Aurela, Mika; Skiba, Ute M.

    2017-02-01

    Subarctic and boreal emissions of CH4 are important contributors to the atmospheric greenhouse gas (GHG) balance and subsequently the global radiative forcing. Whilst N2O emissions may be lower, the much greater radiative forcing they produce justifies their inclusion in GHG studies. In addition to the quantification of flux magnitude, it is essential that we understand the drivers of emissions to be able to accurately predict climate-driven changes and potential feedback mechanisms. Hence this study aims to increase our understanding of what drives fluxes of CH4 and N2O in a subarctic forest/wetland landscape during peak summer conditions and into the shoulder season, exploring both spatial and temporal variability, and uses satellite-derived spectral data to extrapolate from chamber-scale fluxes to a 2 km × 2 km landscape area.From static chamber measurements made during summer and autumn campaigns in 2012 in the Sodankylä region of northern Finland, we concluded that wetlands represent a significant source of CH4 (3.35 ± 0.44 mg C m-2 h-1 during the summer campaign and 0.62 ± 0.09 mg C m-2 h-1 during the autumn campaign), whilst the surrounding forests represent a small sink (-0.06 ± < 0.01 mg C m-2 h-1 during the summer campaign and -0.03 ± < 0.01 mg C m-2 h-1 during the autumn campaign). N2O fluxes were near-zero across both ecosystems.We found a weak negative relationship between CH4 emissions and water table depth in the wetland, with emissions decreasing as the water table approached and flooded the soil surface and a positive relationship between CH4 emissions and the presence of Sphagnum mosses. Temperature was also an important driver of CH4 with emissions increasing to a peak at approximately 12 °C. Little could be determined about the drivers of N2O emissions given the small magnitude of the fluxes.A multiple regression modelling approach was used to describe CH4 emissions based on spectral data from PLEIADES PA1 satellite imagery across a 2 km

  18. Soil CO2, CH4, and N2O fluxes from an afforested lowland raised peatbog in Scotland: implications for drainage and restoration

    Directory of Open Access Journals (Sweden)

    J. I. L. Morison

    2012-06-01

    Full Text Available The effect of tree (lodgepole pine planting with and without intensive drainage on soil greenhouse gas fluxes was assessed after 45 yr at a raised peatbog in West Flanders Moss, central Scotland. Fluxes of CO2, CH4 and N2O from the soil were monitored over a 2-yr period every 2 to 4 weeks using the static opaque chamber method in a randomised experimental block trial with the following treatments: drained and planted (DP, undrained and planted (uDP, undrained and unplanted (uDuP, and for reference also from an adjoining near pristine area of bog at East Flanders Moss (n-pris. There was a strong seasonal pattern in both CO2 and CH4 effluxes which were significantly higher in late spring and summer months, reflecting seasonal temperature changes. Effluxes of N2O were low and no significant differences were observed between the treatments. Annual CH4 emissions increased with the proximity of the water table to the soil surface across treatments in the order: DP 4 ha−1 yr−1, respectively. For CO2, effluxes increased in the order uDP 2 ha−1 yr−1, respectively. CO2 effluxes dominated the calculated global warming potential (GWP of the net fluxes for each treatment (76–98%, and only in the n-pris site was CH4 a substantial contribution (23%. Based on soil effluxes only, the near pristine (n-pris peatbog had 43% higher net GWP compared with the DP treatment because of high CH4 effluxes and the DP treatment had 33% higher GWP compared with the uDP because drainage increased CO2 effluxes. Restoration is likely to increase CH4 emissions, but reduce CO2 effluxes. Including estimates of CO2 uptake by vegetation from similar peatbog sites suggests that the total GWP of restored peatbog would be about half that of the peatbog covered by woodland.

  19. Spatial variability and temporal dynamics of greenhouse gas (CO2, CH4, N2O concentrations and fluxes along the Zambezi River mainstem and major tributaries

    Directory of Open Access Journals (Sweden)

    C. R. Teodoru

    2014-11-01

    Full Text Available Spanning over 3000 km in length and with a catchment of approximately 1.4 million km2, the Zambezi River is the fourth largest river in Africa and the largest flowing into the Indian Ocean from the African continent. As part of a~broader study on the riverine biogeochemistry in the Zambezi River basin, we present data on greenhouse gas (GHG, carbon dioxide (CO2, methane (CH4, and nitrous oxide (N2O concentrations and fluxes collected along the Zambezi River, reservoirs and several of its tributaries during 2012 and 2013 and over two climatic seasons (dry and wet to constrain the interannual variability, seasonality and spatial heterogeneity along the aquatic continuum. All GHGs concentrations showed high spatial variability (coefficient of variation: 1.01 for CO2, 2.65 for CH4 and 0.21 for N2O. Overall, there was no unidirectional pattern along the river stretch (i.e. decrease or increase towards the ocean, as the spatial heterogeneity of GHGs appeared to be determined mainly by the connectivity with floodplains and wetlands, and the presence of man-made structures (reservoirs and natural barriers (waterfalls, rapids. Highest CO2 and CH4 concentrations in the mainstream river were found downstream of extensive floodplains/wetlands. Undersaturated CO2 conditions, in contrast, were characteristic for the surface waters of the two large reservoirs along the Zambezi mainstem. N2O concentrations showed the opposite pattern, being lowest downstream of floodplains and highest in reservoirs. Among tributaries, highest concentrations of both CO2 and CH4 were measured in the Shire River whereas low values were characteristic for more turbid systems such as the Luangwa and Mazoe rivers. The interannual variability in the Zambezi River was relatively large for both CO2 and CH4, and significantly higher concentrations (up to two fold were measured during wet seasons compared to the dry season. Interannual variability of N2O was less pronounced but generally

  20. Full accounting of the greenhouse gas (CO2, N2O, CH4) budget of nine European grassland sites

    DEFF Research Database (Denmark)

    Soussana, J.E.; Allard, V.; Pilegaard, Kim

    2007-01-01

    grasslands across Europe (sown, intensive permanent and semi-natural grassland) and contrasted nitrogen fertilizer supplies. At all sites, the net ecosystem exchange (NEE) of CO2 was assessed using the eddy covariance technique. N2O emissions were monitored using various techniques (GC-cuvette systems...

  1. [Observation for CH4 and N2O emissions under different rates of nitrogen and phosphate fertilization in double rice fields].

    Science.gov (United States)

    Shi, Sheng-Wei; Li, Yu-E; Wan, Yun-Fan; Qin, Xiao-Bo; Gao, Qing-Zhu

    2011-07-01

    Two non-CO2 greenhouse gas emissions (methane and nitrous oxide) and related environmental factors were measured within rice growing season under five treatments including non-fertilization (CK), balanced fertilization (BF), decreased nitrogen and phosphate 1 (DNP1), decreased nitrogen and phosphate 2 (DNP2) and increased nitrogen and phosphate 1 (INP) in double rice fields of red clay soil in 2009, using the method of static chamber-gas chromatograph techniques. The results showed that the average CH4 emission fluxes for treatments of BF, DNP1, DNP2 and INP were 4.57, 5.42, 4.70 and 4.65 mg x (m2 x h)(-1) during early rice growing period, which increased by 39%, 49%, 41% and 40% compared with non-fertilizer treatment, respectively. The average CH4 emission fluxes in late rice growing season was higher than preseason's. Compared to CK, CH4 emission increased by 11%, 1%, 26% and - 4% in treatments of BF, DNP1, DNP2 and INP within late rice growing season. Applying nitrogen and phosphate enhanced CH4 emission in turning green period for early and late rice. No significant difference was observed between the CH4 emissions of five treatments during early and late rice growing season (p > 0.05). N2O emission was very little during mid-seasonal drainage period. In contrast, N2O emission peaks were observed in period of alternation of wetting and drying after mid-seasonal drainage in this experiment. N2O emission was, on average, equivalent to 0.18% of the nitrogen applied in double rice growing season. Statistically, air temperature, soil Eh and soil moisture (water-filled pore space, WFPS) at 0-10cm depth significantly affected the fluctuations of the seasonal CH4 flux, but no significant correlationship has been found between N2O flux and related environmental factors. CH4 was the dominated greenhouse gas in double rice fields which contributed approximately 90% for the integrated global warming potential of CH4 and N2O released during the rice growing season

  2. Full greenhouse gas balance (CO2, N2O, CH4) of a bioenergy plantation (POPFULL) converted from agriculture and pasture: carbon debt and climate sensitivity

    Science.gov (United States)

    Zona, D.; Janssens, I.; Ceulemans, R.

    2012-04-01

    Bioenergy from biomass is currently receiving a lot of attention as an energy source alternative to fossil fuels. Bioenergy could have a lower impact on the environment and supposedly lower greenhouse gas emissions. There are, however, still many uncertainties on the claimed "climate neutrality" of bioenergy plantations. A major concern regards the carbon (C) debt from the land use change connected to the establishment of these bioenergy plantations. Land use conversion has been proved to lead to large C emissions, which may require years to decades to be paid off by the C sequestered in the plantations. In this study we report on the greenhouse gas fluxes (CO2, CH4, and N2O) deriving from the conversion of pasture and agricultural fields into a short-rotation poplar plantation for bio-energy. The establishment of the plantation led to a large overall CO2 and N2O loss during the first year. Nitrous oxides represented 50% of the overall greenhouse gas balance, which was mostly connected to a week-long peak emission following an extreme rainfall event during the first season. The week-long peak N2O emission event represented most of the total annual N2O emission during the first year. The second year was characterized by a much lower N2O emission and a much larger CO2 uptake, with the CO2 uptake being clearly water-limited for most of the summer season. Over the two years CH4 fluxes were constantly very low, consistent with the fact that sandy soils do not support a significant methanogenic community.

  3. Technical Note: Latitude-time variations of atmospheric column-average dry air mole fractions of CO2, CH4 and N2O

    Directory of Open Access Journals (Sweden)

    M. Rettinger

    2012-08-01

    Full Text Available We present a comparison of an atmospheric general circulation model (AGCM-based chemistry-transport model (ACTM simulation with total column measurements of CO2, CH4 and N2O from the Total Carbon Column Observing Network (TCCON. The model is able to capture observed trends, seasonal cycles and inter hemispheric gradients at most sampled locations for all three species. The model-observation agreements are best for CO2, because the simulation uses fossil fuel inventories and an inverse model estimate of non-fossil fuel fluxes. The ACTM captures much of the observed seasonal variability in CO2 and N2O total columns (~81 % variance, R>0.9 between ACTM and TCCON for 19 out of 22 cases. These results suggest that the transport processes in troposphere and stratosphere are well represented in ACTM. Thus the poor correlation between simulated and observed CH4 total columns, particularly at tropical and extra-tropical sites, have been attributed to the uncertainties in surface emissions and loss by hydroxyl radicals. While the upward-looking total column measurements of CO2 contains surface flux signals at various spatial and temporal scales, the N2O measurements are strongly affected by the concentration variations in the upper troposphere and stratosphere.

  4. Decadal variability of soil CO2 NO, N2O, and CH4 fluxes at the Höglwald Forest, Germany

    Directory of Open Access Journals (Sweden)

    K. Butterbach-Bahl

    2011-12-01

    Full Text Available Besides agricultural soils, temperate forest soils have been identified as significant sources of or sinks for important atmospheric trace gases (N2O, NO, CH4, and CO2. Although the number of studies for this ecosystem type increased more than tenfold during the last decade, studies covering an entire year and spanning more than 1–2 yr remained scarce. This study reports the results of continuous measurements of soil-atmosphere C- and N-gas exchange with high temporal resolution carried out since 1994 at the Höglwald Forest spruce site, an experimental field station in Southern Germany. Annual soil N2O emission, NO emission, CH4 uptake, and CO2 emission (1994–2010 varied in a range of 0.2–3.2 kg N2O-N ha−1 yr−1, 6.4–11.4 kg NO-N ha−1 yr−1, 0.9–3.5 kg CH4-C ha−1 yr−1, and 7.0–9.2 t CO2-C ha−1 yr−1, respectively. The observed high fluxes of N-trace gases are most likely a consequence of high rates of atmospheric nitrogen deposition (> 20 kg N ha−1 yr−1 of NH3 and NOx to our site. For N2O cumulative annual emissions were > 0.8 kg N2O-N ha−1 yr−1 high in years with freeze-thaw events (5 out 14 yr. This shows that long-term, multi-year measurements are needed to obtain reliable estimates of N2O fluxes for a given ecosystem. Cumulative values of soil respiratory CO2 fluxes were highest in years with prolonged freezing periods e.g. the years 1996 and 2006, i.e. years with below average annual mean soil temperatures and high N2O emissions. The results indicate that long freezing periods may even drive increased CO2 fluxes not only during soil thawing but also throughout the following growing season. Furthermore, based on our unique database on GHGs we analyzed if soil temperature, soil moisture, or precipitation measurements can be used to approximate GHGs at weekly, monthly, or annual scale. Our analysis shows that simple-to-measure environmental drivers such as soil temperature or soil moisture are suitable to

  5. The development and evaluation of airborne in situ N2O and CH4 sampling using a Quantum Cascade Laser Absorption Spectrometer (QCLAS)

    Science.gov (United States)

    Pitt, Joseph; Le Breton, Michael; Allen, Grant; Percival, Carl; Gallagher, Martin; Bauguitte, Stephane; O'Shea, Sebastian; Muller, Jennifer; Zahniser, Mark; Pyle, John; Palmer, Paul

    2016-04-01

    Spectroscopic measurements of atmospheric N2O and CH4 mole fractions were made on board the FAAM (Facility for Airborne Atmospheric Measurements) large Atmospheric Research Aircraft. We evaluate the performance of the mid-IR continuous wave Aerodyne Research Inc. Quantum Cascade Laser Absorption Spectrometer (QCLAS) employed over 17 flights conducted during summer 2014. Two different methods of correcting for the influence of water vapour on the spectroscopic retrievals are compared and evaluated. Test flight data demonstrating the sensitivity of the instrument to changes in cabin pressure is presented, and a new in-flight calibration procedure to account for this issue is described and assessed. Total 1σ uncertainties of 1.81 ppb for CH4 and 0.35 ppb for N2O are derived. We report a mean difference in 1 Hz CH4 mole fraction of 2.05 ppb (1σ = 5.85 ppb) between in-flight measurements made using the QCLAS and simultaneous measurements using a previously characterised Los Gatos Research Fast Greenhouse Gas Analyser (FGGA).

  6. Differences in carbon density and soil CH4/N2O flux among remnant and agro-ecosystems established since European settlement in the Mornington Peninsula, Australia.

    Science.gov (United States)

    Livesley, Stephen J; Idczak, Daniel; Fest, Benedikt J

    2013-11-01

    National and regional C emissions from historical land use change (LUC) and fossil fuel use are proposed as a basis to ascribe 'burden-sharing' for global emission reduction targets. Changes in non-CO2 greenhouse gas emissions as a result of LUC have not been considered, but may be considerable. We measured soil-atmosphere exchange of methane (CH4) and nitrous oxide (N2O) in remnant forest, pasture and viticulture systems in four seasons, as well as differences in soil C density and the C density of remnant forest vegetation. This approach enabled comparative assessment of likely changes in ecosystem C density and soil non-CO2 greenhouse gas exchange along a LUC continuum since European settlement. Soil CH4 uptake was moderate in forest soil (-27 μg C m(-2) h(-1)), and significantly different to occasionally large CH4 emissions from viticulture and pasture soils. Soil N2O emissions were small and did not significantly differ. Soil C density increased significantly with conversion from forest (5 kg m(-2)) to pasture (9 kg m(-2)), and remained high in viticulture. However, there was a net decrease in ecosystem C density with forest conversion to pasture. Concurrently, net soil non-CO2 emissions (CH4 and N2O combined) increased with conversion from forest to pasture. Since European settlement 170 years ago, it was estimated ~8114 Gg CO2-e has been released from changes in ecosystem C density in the Mornington Peninsula, whereas ~383 Gg CO2-e may have been released from changes in soil non-CO2 exchange processes. Principally, a switch from soil CH4 uptake to soil CH4 emission after forest clearing to agro-pastoral systems provided this further ~5% contribution to the historical landscape CO2-e source strength. Conserving and restoring remnant forests and establishing new tree-based systems will enhance landscape C density. Similarly, minimising anaerobic, wet conditions in pasture/viticulture soils will help reduce non-CO2 greenhouse gas emissions.

  7. Effects of N loading rate on CH4 and N2O emissions during cultivation and fallow periods from forage rice fields fertilized with liquid cattle waste.

    Science.gov (United States)

    Riya, S; Zhou, S; Kobara, Y; Sagehashi, M; Terada, A; Hosomi, M

    2015-09-15

    The use of liquid cattle waste (LCW) as a fertilizer for forage rice is important for material recycling because it can promote biomass production, and reduce the use of chemical fertilizer. Meanwhile, increase in emission of greenhouse gases (GHGs), especially CH4 and N2O would be concerned. We conducted a field study to determine the optimum loading rate of LCW as N to promote forage rice growth with lower GHG emissions. The LCW was applied to forage rice fields, N100, N250, N500, and N750, at four different N loading rates of 107, 258, 522, and 786 kg N ha(-1), respectively, including 50 kg N ha(-1) of basal chemical fertilizer. The above-ground biomass yields increased 14.6-18.5 t ha(-1) with increases in N loading rates. During the cultivation period, both the CH4 and N2O fluxes increased with increases in LCW loading rates. In the treatments of N100, N250, N500, and N750, the cumulative CH4 emissions during the entire period, including cultivation and fallow period were 29.6, 18.1, 54.4, and 67.5 kg C ha(-1), respectively, whereas those of N2O were -0.15, -0.02, 1.49, and 5.82 kg N ha(-1), respectively. Considering the greenhouse gas emissions and above-ground biomass, the yield-scaled CO2-equivalents (CO2-eqs) were 66.3, 35.9, 161, and 272 kg CO2 t(-1) for N100, N250, N500, and N750, respectively. These results suggest that N250 is the most appropriate LCW loading rate for promoting forage rice production with lower GHG emissions.

  8. Total Cross Sections for Electron Scattering on Polyatomic Molecules (CH4, CO2,NO2, and N2O) at 10 ~ 3000 eV

    Institute of Scientific and Technical Information of China (English)

    SUN Jin-Feng; XU Bin; LIU Yu-Fang; SHI De-Heng

    2005-01-01

    A new modified formulation of the Additivity Rule (AR) was proposed to calculate the total electron scattering cross sections for CH4, CO2, NO2, and N2O, considering the overlapping between atoms in molecules and the not fully transparency of the molecules. The present calculation covers the range of impact energy from 10 to 3000 eV. The results are compared with experimental data and other theories where available. The atoms are presented by spherical complex optical potential, which is composed of static, exchange, polarization, and absorption terms.

  9. Comparisons between SCIAMACHY and ground-based FTIR data for total columns of CO, CH4, CO2 and N2O

    Directory of Open Access Journals (Sweden)

    B. Dils

    2006-01-01

    Full Text Available Total column amounts of CO, CH4, CO2 and N2O retrieved from SCIAMACHY nadir observations in its near-infrared channels have been compared to data from a ground-based quasi-global network of Fourier-transform infrared (FTIR spectrometers. The SCIAMACHY data considered here have been produced by three different retrieval algorithms, WFM-DOAS (version 0.5 for CO and CH4 and version 0.4 for CO2 and N2O, IMAP-DOAS (version 1.1 and 0.9 (for CO and IMLM (version 6.3 and cover the January to December 2003 time period. Comparisons have been made for individual data, as well as for monthly averages. To maximize the number of reliable coincidences that satisfy the temporal and spatial collocation criteria, the SCIAMACHY data have been compared with a temporal 3rd order polynomial interpolation of the ground-based data. Particular attention has been given to the question whether SCIAMACHY observes correctly the seasonal and latitudinal variability of the target species. The present results indicate that the individual SCIAMACHY data obtained with the actual versions of the algorithms have been significantly improved, but that the quality requirements, for estimating emissions on regional scales, are not yet met. Nevertheless, possible directions for further algorithm upgrades have been identified which should result in more reliable data products in a near future.

  10. Active standoff detection of CH4 and N2O leaks using hard-target backscattered light using an open-path quantum cascade laser sensor

    Science.gov (United States)

    Diaz, Adrian; Thomas, Benjamin; Castillo, Paulo; Gross, Barry; Moshary, Fred

    2016-05-01

    Fugitive gas emissions from agricultural or industrial plants and gas pipelines are an important environmental concern as they contribute to the global increase of greenhouse gas concentrations. Moreover, they are also a security and safety concern because of possible risk of fire/explosion or toxicity. This study presents standoff detection of CH4 and N2O leaks using a quantum cascade laser open-path system that retrieves path-averaged concentrations by collecting the backscattered light from a remote hard target. It is a true standoff system and differs from other open-path systems that are deployed as point samplers or long-path transmission systems that use retroreflectors. The measured absorption spectra are obtained using a thermal intra-pulse frequency chirped DFB quantum cascade laser at ~7.7 µm wavelength range with ~200 ns pulse width. Making fast time resolved observations, the system simultaneously realizes high spectral resolution and range to the target, resulting in path-averaged concentration retrieval. The system performs measurements at high speed ~15 Hz and sufficient range (up to 45 m, ~148 feet) achieving an uncertainty of 3.1 % and normalized sensitivity of 3.3 ppm m Hz-1/2 for N2O and 9.3 % and normalized sensitivity of 30 ppm m Hz-1/2 for CH4 with a 0.31 mW average power QCL. Given these characteristics, this system is promising for mobile or multidirectional search and remote detection of gas leaks.

  11. CH4 and N2O Emissions from Rice Paddy Soils in Vietnam - Identifying Regional Hotspots and Quantifying the Total Emission Strength using a Biogeochemical Model

    Science.gov (United States)

    Werner, C.; Kraus, D.; Mai, T. V.; Butterbach-Bahl, K.

    2016-12-01

    Agriculture is the economic backbone for over two thirds of Vietnam's population, providing food security, employment and income. However, agriculture in Vietnam is challenged by climate change and climate extremes and at the same time, agriculture remains a key source of greenhouse gas (GHG) emissions. The first bi-annual update report (BUR1), published in 2014 indicated that while the proportion of GHG emissions from agriculture had fallen from 43.1% to 33.2% from 2000 to 2010, the emission total increased from 65.1 mio to 88.4 mio t CO2e. Reducing GHG emissions from agriculture has thus become a key issue within the national strategy of GHG emission management. Here we present first data using IPCC Tier 3 modeling for quantifying the source strength of rice based crop systems for CH4 and N2O. We used LandscapeDNDC and linked it to a newly developed spatial landuse and land management database (climate, soil properties, and detailed field management data). Site application showed good agreement of simulated biomass, yield and GHG emissions with field observations, providing confidence for model use at national scale. Our results also show good agreement with national yield data and total annual emissions of the simulated period (2006-2015) ranged from 1060 - 1502 kt CH4 and 6.2 - 7.7 kt N2O, respectively. The dominating emission hotspot for CH4 is the Mekong Delta region with its double and triple rice cropping systems (819 kt CH4/yr, Fig. 1). With regard to N2O, emission hotspots have been identified to be closely related to regions with high fertilizer use and single to double rice cropping systems (Fig. 1). Though, our emission estimates are likely representing the best of current knowledge on national GHG emissions from rice based systems in Vietnam, the uncertainty is significant as information on rice system management remains vague. Sensitivity studies show that changes in field management affecting the soil organic carbon dynamics (duration of flooding

  12. Comparison of analytical procedures to estimate CH4 and N2O fluxes from a two-year ecosystem study in a constructed wetland system

    Science.gov (United States)

    Ramos, J., Jr.; Chapman, E. J.; Weller, N.; Susanto, P.; Childers, D. L.

    2014-12-01

    Constructed wetland systems (CWS) have been developed to remove nutrients from secondarily treated water, but little is known about their long-term contributions on greenhouse gas emissions (GHG), especially in arid regions. To increase our knowledge of ecosystem dynamics of CWS in arid regions, we are investigating N2O, CH4, and CO2 fluxes from a system perspective, a vegetated-shoreline to open-water gradient, and from the wetland plant Typha spp. From 2012 to 2014, we utilized the floating chamber technique to collect fluxes from two transects (nearest to inflow and nearest to outflow) and along two gradient subsites (shoreline and open-water) within the transects. Recently, we began collecting direct fluxes from the vegetation by deploying gas chambers on Typha spp. Fluxes were analyzed using the HMR procedure (Package HMR in R) developed for trace-gas flux estimations when using static chambers. We found significantly higher CH4 and CO2 fluxes in the summer and spring compared to fall and winter months. From the whole system perspective, we found significantly greater CO2 fluxes at the inflow compared to the outflow transect. From the shoreline to open-water gradient, N2O fluxes were significantly greater in the open-water and, CH4 fluxes where significantly greater in the vegetated shoreline subsite. These differences may be explained by the presence of vegetation, differences of water column height, or higher nitrate levels in the open-water compared to the shoreline. Results from the vegetation chambers will be presented from two heights of the Typha spp. leaves from plants in each of the four subsites. The analysis of the 288 fluxes using two HMR procedures, default classification (linear, non-linear, and no flux) and the linear regression, resulted in similar seasonal and spatial patterns in the flux estimates. However, the default classification calculated on average 31% for N2O, 67% for CH4, and 34% for CO2 higher flux estimates relative to the fluxes

  13. Effects of nitrogen conversion and environmental factors on landfill CH4 oxidation and N2O emissions in aged refuse.

    Science.gov (United States)

    Zhang, Houhu; Zhao, Keqiang; Yan, Xiaofei; Sun, Qinfang; Li, Yi; Zhang, Yi; Zun, Zhao; Ke, Fan

    2013-09-15

    We determined the effects of nitrification capacity and environmental factors on landfill methane oxidation potential (MOP) using an aged refuse in laboratory batch assays and compared it with two different types of soils. The nitrogen conversion in the three experimental materials after 120 h incubation yielded first-order reaction kinetics at an initial concentration of 200 mg kg(-1) NH4(+)-N. The net nitrification rate for the aged refuse was 1.50 (p bacteria during CH4 co-oxidation, the average value of the MOP in the aged refuse at a temperature range of 4-45 °C was 2.34 (p landfill can be neglected after applying an aged refuse bio-cover because of the much higher MOP in the aged refuse. The calculated maximum MOP value in the aged refuse was 12.45 μmol g(-1) d.w. h(-1), which was much higher than the documented data.

  14. Online technique for isotope and mixing ratios of CH4, N2O, Xe and mixing ratios of organic trace gases on a single ice core sample

    Directory of Open Access Journals (Sweden)

    J. Schmitt

    2014-03-01

    Full Text Available Polar ice cores enclosing trace gas species offer a unique archive to study changes in the past atmosphere and in terrestrial/marine source regions. Here we present a new online technique for ice core and air samples to measure a suite of isotope ratios and mixing ratios of trace gas species on a single small sample. Isotope ratios are determined on methane, nitrous oxide and xenon with reproducibilities for ice core samples of 0.15‰ for δ13C-CH4, 0.22‰ for δ15N-N2O, 0.34 ‰ for δ18O-N2O, and 0.05‰ for δ136Xe. Mixing ratios are determined on methane, nitrous oxide, xenon, ethane, propane, methyl chloride and dichloro-difluoromethane with reproducibilities of 7 ppb for CH4, 3 ppb for N2O, 50 ppt for 136Xe, 70 ppt for C2H6, 70 ppt for C3H8, 20 ppt for CH3Cl, and 2 ppt for CCl2F2. The system consists of a vacuum extraction device, a preconcentration unit and a gas chromatograph coupled to an isotope ratio mass spectrometer. CH4 is combusted to CO2 prior to detection while we bypassed the oven for all other species. The highly automated system uses only ~160 g ice, equivalent to ~16 mL air, which is less than previous methods. This large suite of parameters on a single ice sample is new and helpful to study phase relationships of parameters which are usually not measured together. A multi-parameter dataset is also key to understand in situ production processes of organic species in the ice, a critical issue observable in many organic trace gases. Novel is the determination of xenon isotope ratios using doubly charged Xe ions. The attained precision for δ136Xe is suitable to correct the isotopic ratios and mixing ratios for gravitational firn effects, with the benefit that this information is derived from the same sample. Lastly, anomalies in the Xe mixing ratio, δXe/air, can be used to detect melt layers.

  15. Simultaneous and continuous measurements of dissolved CO2, CH4, N2O and CO in rivers using Fourier-Transform-InfraRed (FTIR) spectrometry

    Science.gov (United States)

    Warneke, Thorsten; Müller, Denise; Caldow, Christopher; Rixen, Tim; Notholt, Justus

    2015-04-01

    We have coupled a Fourier-Transform InfraRed (FTIR) trace gas analyser to an equilibrator, which allows the simultaneous and continuous measurement of dissolved CO2, CH4, N2O and CO in water. The FTIR-technique has a high precision over a wide range of concentrations, making it very suitable for the measurement of these gases in freshwater systems. We have employed this measurement system on a commercial river barge on the Elbe river (Czech Republic, Germany) and on a fisher boat in the coastal area of Sarawak (Malaysia). In addition we have performed stationary continuous measurements at a small river in Northern Germany over the duration of 3 months. The presentation will outline the advantages and disadvantages of the FTIR-technique for freshwater measurements and will present results from the measurement campaigns.

  16. A single gas chromatograph for accurate atmospheric mixing ratio measurements of CO2, CH4, N2O, SF6 and CO

    Directory of Open Access Journals (Sweden)

    H. A. J. Meijer

    2009-09-01

    Full Text Available We present an adapted gas chromatograph capable of measuring simultaneously and semi-continuously the atmospheric mixing ratios of the greenhouse gases CO2, CH4, N2O and SF6 and the trace gas CO with high precision and long-term stability. The novelty of our design is that all species are measured with only one device, making it a very cost-efficient system. No time lags are introduced between the measured mixing ratios. The system is designed to operate fully autonomously which makes it ideal for measurements at remote and unmanned stations. Only a small amount of sample air is needed, which makes this system also highly suitable for flask air measurements. In principle, only two reference cylinders are needed for daily operation and only one calibration per year against international WMO standards is sufficient to obtain high measurement precision and accuracy. The system described in this paper is in use since May 2006 at our atmospheric measurement site Lutjewad near Groningen, The Netherlands at 6°21´ E, 53°24´N, 1 m a.s.l. Results show the long-term stability of the system. Observed measurement precisions at our remote research station Lutjewad were: ±0.04 ppm for CO2, ±0.8 ppb for CH4, ±0.8 ppb for CO, ±0.3 ppb for N2O, and ±0.1 ppt for SF6. The ambient mixing ratios of all measured species as observed at station Lutjewad for the period of May 2007 to August 2008 are presented as well.

  17. Soil-atmosphere fluxes of the greenhouse gases N2O, CO2 and CH4 from a long term compost experiment in Austria.

    Science.gov (United States)

    Spann, Caroline; Spiegel, Heide; Kitzler, Barbara

    2016-04-01

    The application of composts as fertilizers is becoming increasingly important to achieve a closed-loop economy. However, greenhouse gas (GHG) emissions, especially N2O, from agricultural fields may increase as well. In this study different compost types and N amounts were investigated, especially in terms of their GHG fluxes. We used the closed chamber method to estimate GHG flux rates over one vegetation period from an agricultural soil fertilized with different compost types. The study was conducted on a long term compost experiment site near Linz (Austria) with a crop rotation. The soil is a loamy silt and in 2015 maize was planted. Six different compost treatments were investigated. Organic waste compost (OWC) and farmyard manure compost (FMC) was applied with nitrogen concentrations of 175 (OWC1, FYC1) and 525 kg N ha-1 (OWC3, FYC3). Two compost treatments were fertilized additionally with 80 kg N ha.1 mineral fertilizer (OWC2, FYC2). One treatment (TN) was fertilized only with mineral fertilizer (120 kg N ha-1) and one treatment was not fertilized at all (C). Additionally to the GHG flux rates, ammonium and nitrate content, microbial biomass C and N and different enzyme activities were analysed in the top soil. Nitrous oxide (N2O) was emitted over the entire vegetation period with highest fluxes from April until June, until the plants have been established sufficiently. Overall, at the FMC treatments (FYC2, FYC3) highest fluxes were measured. Compared to FMC, lower N2O emissions were measured from the OWC treatments. The combination of compost and mineral N fertilization resulted in the highest N2O emissions, especially after precipitation events. The treatments OWC1 and FYC1 were not different from the control. Methane (CH4) was mainly taken up at all treatments, but uptake rates were lower at the high N input sites (OWC3, FYC3) with no differences between the compost types. No significant differences were found in the soil respiration rates.

  18. Space-borne remote sensing with active optical instruments for the measurement of temperature, pressure, ozone and the greenhouse gases CO2, CH4, and N2O

    Science.gov (United States)

    Ehret, G.; Fix, A.; Kiemle, C.; Wirth, M.

    Lidar Light Detection and Ranging is regarded as an innovative component of the global observing system It offers the possibility to directly sample the four-dimensional variability of the atmosphere with unprecedented accuracy and spatial resolution In Europe space-borne lidar systems have been the subject of extensive investigations since mid 1970 s resulting in mission and instrument concepts such as ATLID a backscatter lidar for aerosol and clouds for the EarthCARE mission or ALADIN a Doppler wind lidar considered for the ADM Aeolus mission Major advances particularly in humidity profiling are expected from the space-borne Differential Absorption Lidar DIAL being the Core instrument of the WALES Water Vapour Lidar Experiment in Space mission which was studied up to a level of Phase A In this presentation we report on the background definition of a future lidar system capable of monitoring the greenhouse gases carbon dioxide CO 2 methane CH 4 and nitrous oxide N 2 O stratospheric and tropospheric ozone O 3 and the meteorological parameter pressure p and temperature T The idea of this study which was initiated by the European Space Agency ESA was to select one or two candidate instruments for follow-on activities on sensor and mission level For each parameter appropriate performance models of active optical instruments either for range-resolved or for total column measurements were defined and implemented as computer codes for parametric analysis The sampling strategy and error characteristics for the

  19. [Effects of combined applications of pig manure and chemical fertilizers on CH4 and N2O emissions and their global warming potentials in paddy fields with double-rice cropping].

    Science.gov (United States)

    Wang, Cong; Shen, Jian-Lin; Zheng, Liang; Liu, Jie-Yun; Qin, Hong-Ling; Li, Yong; Wu, Jin-Shui

    2014-08-01

    A field experiment was carried out to study the effects of combined applications of pig manure and chemical fertilizers on CH4 and N2O emissions, which were measured using the static chamber/gas chromatography method, and their global warming potentials in typical paddy fields with double-rice cropping in Hunan province. The results showed that the combined applications of pig manure and chemical fertilizers did not change the seasonal patterns of CH4 and N2O emissions from paddy soils, but significantly changed the magnitudes of CH4 and N2O fluxes in rice growing seasons as compared with sole application of chemical fertilizers. During the two rice growing seasons, the cumulative CH4 emissions for the pig manure and chemical nitrogen (N) fertilizer each contributing to 50% of the total applied N (1/2N + PM) treatment were higher than those for the treatments of no N fertilizer (ON), half amount of chemical N fertilizer (1/2N) and 100% chemical N fertilizer (N) by 54.83%, 33.85% and 43.30%, respectively (P fertilizers in paddy fields would increase the GWP of CH4 and N2O emissions during rice growing seasons and this effect should be considered in regional greenhouse gases emissions inventory.

  20. Influence of biomass harvesting on fluxes of CO2 CH4 and N2O for a sedge fen in south-west Belarus

    Science.gov (United States)

    Burlo, A.; Minke, M.; Chuvashova, H.; Yarmashuk, T.; Augustin, J.; Thiele, A.; Tichonov, V.; Liashchynskaya, N.; Narkevitch, I.

    2012-04-01

    Until now, it is usual to drain a peatland to be able to use it economically. The consequences are a progressive peat loss and a negative climate impact caused by a strong emission of the greenhouse gases CO2 and N2O (Droesler et al., 2008). To avoid these negative effects of the peatland use, the concept of the so-called Paludiculture was developed. This is the harvest of plant biomass on wet and rewetted peatlands (Wichtmann & Joosten 2007). However, there is only few and contradictory information about the actual effect of the Paludiculture on the greenhouse gas fluxes, the peat carbon budget, and the climate balance so far. Therefore, we investigated the influence of late mowing on a sedge fen in the Paliessie region in SW Belarus. The site is characterized by Carex nigra, Carex rostrata, Calamagrostis canescens, Potentilla palustris, Drepanocladus aduncus and Rhizomnium punctatum and a mean water level close to the surface. The investigation covers two variants: Without use (control), and the removal of the aboveground biomass in late autumn. For every variant, we installed three soil collars distributed randomly as a base for the gas flux measurements. Since August 2010 the CO2, CH4 and N2O exchange rates are measured by the closed chamber approach of Droesler (2005). The first harvest of plant biomass was on 17th of November 2010. It turned out, that the single gas fluxes are influenced very differently by the biomass removal. In case of the CH4 a noticeable impact of mowing became evident directly after melting of the ice layer in spring 2011, when the emissions at the harvested plots for nearly doubled those from the control on two measurement campaigns. The N2O fluxes were very week but these are according to tendency lower on the harvest variant all the time. However, the ecosystem respiration did not show any clear reaction on the mowing at all. Furthermore, we will report about the effects of the biomass removal on the current net CO2 exchange, the

  1. [Effects of farming managements on the global warming potentials of CH4 and N2O from a rice-wheat rotation system based on the analysis of DNDC modeling].

    Science.gov (United States)

    Zhang, Xiao-Lin; Pan, Xiao-Jian; Xiong, Zheng-Qin; Wang, Jin-Yang; Yang, Bo; Liu, Ying-Lie; Liu, Ping-Li

    2013-03-01

    Taking a rice-wheat rotation system in the suburb of Nanjing, Jiangsu Province of East China as test object, this paper studied the fluxes of CH4 and N2O and their annual dynamics under different farming managements in 2010-2011, and the field observation data were applied to validate the process-based model, denitrification-decomposition (DNDC) model, aimed to approach the applicability of the model to this rotation system, and to use this model to simulate the effects of different environmental factors and farming managements on the global warming potentials (GWPs) of CH4 and N2O. The results showed that except in the treatment control and during wheat growth season, the simulated cumulative emissions of CH4 and N2O from the rotation system in all treatments were basically in coincide with the observed data, the relative deviations being from 7. 1% to 26.3%, and thus, the DNDC model could be applied to simulate the GWPs of cumulative emissions of CH4 and N2O as affected by various environmental factors or management practices. The sensitivity test showed that the GWPs of CH4 and N2O varied significantly with the changes of environmental factors such as the mean annual air temperature, soil bulk density, soil organic carbon, soil texture, and soil pH. Farming managements such as N fertilization, straw returning, and duration of mid-season drainage also had significant effects on the GWPs of CH4 and NO20. Therefore, the above-mentioned environmental factors and farming managements should be taken into account to estimate the greenhouse gases emission from the rice-wheat cropping system on site-specific or regional scale.

  2. Effects of warming on CO2, N2O and CH4 fluxes and underlying processes from subarctic tundra, Northwest Russia

    Science.gov (United States)

    Voigt, Carolina; Lamprecht, Richard E.; Marushchak, Maija E.; Biasi, Christina; Martikainen, Pertti J.

    2014-05-01

    Peatlands, especially those located in the highly sensitive arctic and subarctic latitudes, are known to play a major role in the global carbon cycle. Predicted climatic changes - entailing an increase in near-surface temperature and a change in precipitation patterns - will most likely have a serious yet uncertain impact on the greenhouse gas (GHG) balance of these ecosystems. Microbial processes are enhanced by warmer temperatures which may lead to increased trace gas fluxes to the atmosphere. However, the response of ecosystem processes and related GHG fluxes may differ largely across the landscape depending on soil type, vegetation cover, and moisture conditions. In this study we investigate how temperature increase potentially reflects on GHG fluxes (CO2, CH4 and N2O) from various tundra surfaces in the Russian Arctic. These surfaces include raised peat plateau complexes, mineral tundra soils, bare surfaces affected by frost action such as peat circles and thermokarst lake walls, as well as wetlands. Predicted temperature increase and climate change effects are simulated by means of open top chambers (OTCs), which are placed on different soil types for the whole snow-free period. GHG fluxes, gas and nutrient concentrations in the soil profile, as well as supporting environmental parameters are monitored for the full growing season. Aim of the study is not only the quantification of aboveground GHG fluxes from the study area, but the linking of those to underlying biogeochemical processes in permafrost soils. Special emphasis is placed on the interface between active layer and old permafrost and its response to warming, since little is known about the lability of old carbon stocks made available through an increase in active layer depth. Overall goal of the study is to gain a better understanding of C and N cycling in subarctic tundra soils and to deepen knowledge in respect to carbon-permafrost feedbacks in respect to climate.

  3. CO2, CH4 and N2O fluxes in an Ultisol treated with sewage sludge and cultivated with castor bean Fluxos de CO2, CH4 e N2O de um Argissolo tratado com lodo de esgoto e cultivado com mamona

    Directory of Open Access Journals (Sweden)

    Jonas Jacob Chiaradia

    2009-12-01

    Full Text Available Organic residue application into soil alter the emission of gases to atmosphere and CO2, CH4, N2O may contribute to increase the greenhouse effect. This experiment was carried out in a restoration area on a dystrophic Ultisol (PVAd to quantify greenhouse gas (GHG emissions from soil under castor bean cultivation, treated with sewage sludge (SS or mineral fertilizer. The following treatments were tested: control without N; FertMin = mineral fertilizer; SS5 = 5 t ha-1 SS (37.5 kg ha-1 N; SS10 = 10 t ha-1 SS (75 kg ha-1 N; and SS20 = 20 t ha-1 SS (150 kg ha-1 N. The amount of sludge was based on the recommended rate of N for castor bean (75 kg ha-1, the N level of SS and the mineralization fraction of N from SS. Soil gas emission was measured for 21 days. Sewage sludge and mineral fertilizers altered the CO2, CH4 and N2O fluxes. Soil moisture had no effect on GHG emissions and the gas fluxes was statistically equivalent after the application of FertMin and of 5 t ha-1 SS. The application of the entire crop N requirement in the form of SS practically doubled the Global Warming Potential (GWP and the C equivalent emissions in comparison with FertMin treatments.A aplicação de resíduos orgânicos no solo pode alterar a emissão de gases para atmosfera e dentre estes, CO2, CH4 e N2O, podem contribuir para o aumento do efeito estufa. Este ensaio foi realizado com o objetivo de quantificar a emissão de gases do efeito estufa (GEE de um Argissolo Vermelho-Amarelo distrófico (PVAd tratado com lodo de esgoto (LE e cultivado com mamoneira em área de reforma de canavial. Os tratamentos testados foram: Controle sem N; FertMin = fertilizante mineral; LE5 = 5 t ha-1 de LE, equivalente a 37,5 kg ha-1 de N; LE10 = 10 t ha-1 de LE, equivalente a 75 kg ha-1 de N; e LE20 = 20 t ha-1 de LE, equivalente a 150 kg ha-1 de N. A quantidade de lodo foi baseada na rate recomendada de N para a mamoneira (75 kg ha-1, nas quantidades de N no LE e na fração de mineraliza

  4. Distribution of dissolved green-house gases (CO2, CH4, N2O) in Lakes Edward and George: Results from the first field cruise of the HIPE project

    Science.gov (United States)

    Borges, Alberto V.; Morana, Cédric D. T.; Lambert, Thibault; Okello, William; Bouillon, Steven

    2017-04-01

    Inland waters (streams, rivers, lakes, reservoirs) are quantitatively important components of the global budgets of atmospheric emissions of long-lived greenhouse gases (GHGs) (CO2, CH4, N2O). Available data indicate that a very large fraction of CO2 and CH4 emissions from rivers and reservoirs occurs at tropical latitudes. Data on GHGs at tropical latitudes from lakes however are much more scarse, and the relative importance of emissions, in particular in Africa, remains to be determined. Large tropical lakes are net autotrophic (hence potentially sinks for atmospheric CO2) due generally low dissolved organic carbon concentrations, seasonally near constant light and temperature conditions, and generally deep water columns favourable for export of organic matter to depth. This sharply contrasts with their much better documented temperate and boreal counterparts, usually considered as CO2 sources to the atmosphere sustained by net heterotrophy. Here, we report a data-set of dissolved CO2, CH4, N2O obtained in October 2016 in Lakes Edward and George and adjacent streams and crater lakes in the frame of Belgian Science Policy (BELSPO) HIPE (Human impacts on ecosystem health and resources of Lake Edward, http://www.co2.ulg.ac.be/hipe/) project. Lake George and part of Lake Edward were sinks for atmospheric CO2 and N2O due to high primary production and denitrification in sediments, respectively, and modest sources of CH4 to the atmosphere. Sampled rivers and streams were oversaturated in CO2 and CH4 and close to atmospheric equilibrium with regards to N2O. Spatial variations within rivers and streams were related to elevation and vegetation characteristics on the catchments (savannah versus forest). Levels of CO2, CH4, and N2O were within the range of those we reported in other African rivers. Crater lakes acted as sinks for atmospheric CO2 and N2O but were extremely over-saturated in CH4, due to intense primary production sustained by cyanobacteria. These CH4 levels

  5. HITRAN2016: Part I. Line lists for H_2O, CO_2, O_3, N_2O, CO, CH_4, and O_2

    Science.gov (United States)

    Gordon, Iouli E.; Rothman, Laurence S.; Tan, Yan; Kochanov, Roman V.; Hill, Christian

    2017-06-01

    The HITRAN2016 database is now officially released. Plethora of experimental and theoretical molecular spectroscopic data were collected, evaluated and vetted before compiling the new edition of the database. The database is now distributed through the dynamic user interface HITRANonline (available at www.hitran.org) which offers many flexible options for browsing and downloading the data. In addition HITRAN Application Programming Interface (HAPI) offers modern ways to download the HITRAN data and use it to carry out sophisticated calculations. The line-by-line lists for almost all of the 47 HITRAN molecules were updated in comparison with the previous compilation (HITRAN2012. Some of the most important updates for major atmospheric absorbers, such as H_2O, CO_2, O_3, N_2O, CO, CH_4, and O_2, will be presented in this talk, while the trace gases will be presented in the next talk by Y. Tan. The HITRAN2016 database now provides alternative line-shape representations for a number of molecules, as well as broadening by gases dominant in planetary atmospheres. In addition, substantial extension and improvement of cross-section data is featured, which will be described in a dedicated talk by R. V. Kochanov. The new edition of the database is a substantial step forward to improve retrievals of the planetary atmospheric constituents in comparison with previous editions, while offering new ways of working with the data. The HITRAN database is supported by the NASA AURA and PDART program grants NNX14AI55G and NNX16AG51G. I. E. Gordon, L. S. Rothman, C. Hill, R. V. Kochanov, Y. Tan, et al. The HITRAN2016 Molecular Spectroscopic Database. JQSRT 2017;submitted. Many spectroscopists and atmospheric scientists worldwide have contributed data to the database or provided invaluable validations. C. Hill, I. E. Gordon, R. V. Kochanov, L. Barrett, J.S. Wilzewski, L.S. Rothman, JQSRT. 177 (2016) 4-14 R.V. Kochanov, I. E. Gordon, L. S. Rothman, P. Wcislo, C. Hill, J. S. Wilzewski

  6. Impacts of Disturbances, Management and Climate Change on Carbon Dynamics and N2O and CH4 Emissions from 1992 to 2050 in the US Great Plains

    Science.gov (United States)

    Liu, S.; li, Z.; Liu, J.; Chen, M.; Gleason, R.; Grangaard, L.; Young, C. J.; Schmidt, G.; Oeding, J.; Davis, B.; Zhu, Z.; Dahal, D.; Abdul-Aziz, O. I.; Sohl, T. L.; Hawbaker, T. J.; Sleeter, B. M.

    2011-12-01

    Natural disturbance, land management, and climate change strongly affect greenhouse gas (GHG) (CO2, CH4 and N2O) emissions from terrestrial ecosystems. Our understanding of current and future GHG emissions at regional to global scales are limited by (1) the scarcity of geospatial data layers characterizing the spatial and temporal change patterns of disturbances and management practices, and (2) the lack of adequate modeling systems that can well represent multiple controlling processes especially those relevant to disturbance and management. As a part of the USGS effort (LandCarbon) to assess ecosystem potentials for carbon sequestration and GHG emission reduction across the United States, we created and synthesized many geospatial data layers on climate change, land cover change, disturbance and land management. Furthermore, we simulated the biogeochemical cycles of carbon and nitrogen of the Great Plains from 1992-2050 using the General Ensemble Biogeochemical Modeling System (GEMS). Land-cover change information was systematically generated using the FOREcasting SCEnarios of future land cover (FORE-SCE) model with reference to the Intergovernmental Panel on Climate Change (IPCC) scenarios (A1B, A2, and B1), the National Land Cover Database (NLCD), US Land Cover Trends product, and the Vegetation Change Tracker (VCT) products. Natural disturbances (e.g., fire, insects, and hurricanes), major management practices (i.e., crop rotation, tillage, etc.) and other relevant information (e.g., atmospheric nitrogen deposition) were constructed based on historical observations and models (e.g., The Integrated Model to Assess the Global Environment (IMAGE)). The GEMS outputs include the carbon pool changes in vegetation, soils, and wood products; the GHG emissions and their global warming potentials, and the lateral movements of carbon and nitrogen caused by soil erosion and deposition. Our results indicated that annual change of carbon stocks in terrestrial ecosystems

  7. Impact of raw pig slurry and pig farming practices on physicochemical parameters and on atmospheric N2O and CH 4 emissions of tropical soils, Uvéa Island (South Pacific).

    Science.gov (United States)

    Roth, E; Gunkel-Grillon, P; Joly, L; Thomas, X; Decarpenterie, T; Mappe-Fogaing, I; Laporte-Magoni, C; Dumelié, N; Durry, G

    2014-09-01

    Emissions of CH4 and N2O related to private pig farming under a tropical climate in Uvéa Island were studied in this paper. Physicochemical soil parameters such as nitrate, nitrite, ammonium, Kjeldahl nitrogen, total organic carbon, pH and moisture were measured. Gaseous soil emissions as well as physicochemical parameters were compared in two private pig farming strategies encountered on this island on two different soils (calcareous and ferralitic) in order to determine the best pig farming management: in small concrete pens or in large land pens. Ammonium levels were higher in control areas while nitrate and nitrite levels were higher in soils with pig slurry inputs, indicating that nitrification was the predominant process related to N2O emissions. Nitrate contents in soils near concrete pens were important (≥ 55 μg N/g) and can thus be a threat for the groundwater. For both pig farming strategies, N2O and CH4 fluxes can reach high levels up to 1 mg N/m(2)/h and 1 mg C/m(2)/h, respectively. CH4 emissions near concrete pens were very high (≥ 10.4 mg C/m(2)/h). Former land pens converted into agricultural land recover low N2O emission rates (≤ 0.03 mg N/m(2)/h), and methane uptake dominates. N2O emissions were related to nitrate content whereas CH4 emissions were found to be moisture dependent. As a result relating to the physicochemical parameters as well as to the gaseous emissions, we demonstrate that pig farming in large land pens is the best strategy for sustainable family pig breeding in Uvéa Islands and therefore in similar small tropical islands.

  8. Validation of the IASI operational CH4 and N2O products using ground-based Fourier Transform Spectrometer: preliminary results at the Izaña Observatory (28ºN, 17ºW

    Directory of Open Access Journals (Sweden)

    Omaira García

    2014-01-01

    Full Text Available Within the project VALIASI (VALidation of IASI level 2 products the validation of the IASI operational atmospheric trace gas products (total column amounts of H2O, O3, CH4, N2O, CO2 and CO as well H2O and O3 profiles will be carried out. Ground-based FTS (Fourier Transform Spectrometer trace gas measurements made in the framework of NDACC (Network for the Detection of Atmospheric Composition Change serve as the validation reference. In this work, we will present the validation methodology developed for this project and show the first intercomparison results obtained for the Izaña Atmospheric Observatory between 2008 and 2012. As example, we will focus on two of the most important greenhouse gases, CH4 and N2O.

  9. Continuous multi-plot measurements of CO2, CH4, N2O and H2O in a managed boreal forest - The importance of accounting for all greenhouse gases

    Science.gov (United States)

    Vestin, P.; Mölder, M.; Sundqvist, E.; Båth, A.; Lehner, I.; Weslien, P.; Klemedtsson, L.; Lindroth, A.

    2015-12-01

    In order to assess the effects of different management practices on the exchange of greenhouse gases (GHG), it is desirable to perform repeated and parallel measurements on both experimental and control plots. Here we demonstrate how a system system combining eddy covariance and gradient techniques can be used to perform this assessment in a managed forest ecosystem.The net effects of clear-cutting and stump harvesting on GHG fluxes were studied at the ICOS site Norunda, Sweden. Micrometeorological measurements (i.e., flux-gradient measurements in 3 m tall towers) allowed for quantification of CO2, CH4 and H2O fluxes (from May 2010) as well as N2O and H2O fluxes (from June 2011) at two stump harvested plots and two control plots. There was one wetter and one drier plot of each treatment. Air was continuously sampled at two heights in the towers and gas concentrations were analyzed for CH4, CO2, H2O (LGR DLT-100, Los Gatos Research) and N2O, H2O (QCL Mini Monitor, Aerodyne Research). Friction velocities and sensible heat fluxes were measured by sonic anemometers (Gill Windmaster, Gill Instruments Ltd). Automatic chamber measurements (CO2, CH4, H2O) were carried out in the adjacent forest stand and at the clear-cut during 2010.Average CO2 emissions for the first year ranged between 14.4-20.2 ton CO2 ha-1 yr-1. The clear-cut became waterlogged after harvest and a comparison of flux-gradient data and chamber data (from the adjacent forest stand) indicated a switch from a weak CH4 sink to a significant source at all plots. The CH4 emissions ranged between 0.8-4.5 ton CO2-eq. ha-1 yr-1. N2O emissions ranged between 0.4-2.6 ton CO2-eq. ha-1 yr-1. Enhanced N2O emission on the drier stump harvested plot was the only clear treatment effect on GHG fluxes that was observed. Mean CH4 and N2O emissions for the first year of measurements amounted up to 29% and 20% of the mean annual CO2 emissions, respectively. This highlights the importance of including all GHGs when assessing

  10. 农田土壤主要温室气体(CO2、CH4N2O)的源/汇强度及其温室效应研究进展%Research advances on source/sink intensities and greenhouse effects of CO2,CH4 and N2O in agricultural soils

    Institute of Scientific and Technical Information of China (English)

    张玉铭; 胡春胜; 张佳宝; 董文旭; 王玉英; 宋利娜

    2011-01-01

    气候变化是当今全球面临的重大挑战,人类社会生产生活引起的温室气体排放是全球气候变暖的主要原因.大气中CO2、CH4和N2O是最重要的温室气体,对温室效应的贡献率占了近80%.据估计,大气中每年有5%~20%的CO2、15%~30%的CH4、80%~90%的N2O来源于土壤,而农田土壤是温室气体的重要排放源.本文重点阐述了农田土壤温室气体产生、排放或吸收机理及其影响因素,指出土地利用方式和农业生产力水平等人为控制因素通过影响土壤和作物生长条件来影响农田土壤温室气体产生与排放或吸收.所以,我们可以从人类活动对农田生态系统的影响着手,通过改善农业生产方式和作物生长条件来探索温室气体减排措施,达到固碳/氨增汇的目的.对国内外关于农田温室气体排放的源/汇强度及其综合温室效应评估的最新研究进展进行了综述,指出正确估算与评价农田土壤温室气体的源/汇强度及其对大气中主要温室气体浓度变化的贡献,有助于为温室气体减排以及减少气候变化预测的不确定性提供理论依据.%Climate change is an increasing global challenge. Greenhouse gas emission via anthropogenic processes is the main cause of global warming. CO3, CH4, and N2O are the main greenhouse gases, accounting for =80% of greenhouse effect. It is estimated that each year, 5%~20% of CO2, 15%-30% of CR, and 80%~90% of N2O in air are emitted from soils. Agricultural soils are the main sources of greenhouse gas emission. This work expatiated the mechanisms and affecting factors of greenhouse gas formation, emission and absorption in agricultural soils. And the contribution of farmland ecosystem to greenhouse effects was discussed. It was indicated that anthropogenic factors such as land use and agricultural activity influenced greenhouse gas formation, emission and absorption in agricultural soils. Because anthropogenic processes

  11. Comparison of CMAM simulations of carbon monoxide (CO, nitrous oxide (N2O, and methane (CH4 with observations from Odin/SMR, ACE-FTS, and Aura/MLS

    Directory of Open Access Journals (Sweden)

    B. Barret

    2009-05-01

    Full Text Available Simulations of CO, N2O and CH4 from a coupled chemistry-climate model (CMAM are compared with satellite measurements from Odin Sub-Millimeter Radiometer (Odin/SMR, Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS, and Aura Microwave Limb Sounder (Aura/MLS. Pressure-latitude cross-sections and seasonal time series demonstrate that CMAM reproduces the observed global CO, N2O, and CH4 distributions quite well. Generally, excellent agreement with measurements is found between CO simulations and observations in the stratosphere and mesosphere. Differences between the simulations and the ACE-FTS observations are generally within 30%, and the differences between CMAM results and SMR and MLS observations are slightly larger. These differences are comparable with the difference between the instruments in the upper stratosphere and mesosphere. Comparisons of N2O show that CMAM results are usually within 15% of the measurements in the lower and middle stratosphere, and the observations are close to each other. However, the standard version of CMAM has a low N2O bias in the upper stratosphere. The CMAM CH4 distribution also reproduces the observations in the lower stratosphere, but has a similar but smaller negative bias in the upper stratosphere. The negative bias may be due to that the gravity drag is not fully resolved in the model. The simulated polar CO evolution in the Arctic and Antarctic agrees with the ACE and MLS observations. CO measurements from 2006 show evidence of enhanced descent of air from the mesosphere into the stratosphere in the Arctic after strong stratospheric sudden warmings (SSWs. CMAM also shows strong descent of air after SSWs. In the tropics, CMAM captures the annual oscillation in the lower stratosphere and the semiannual oscillations at the stratopause and mesopause seen in Aura/MLS CO and N2O observations and in Odin/SMR N2O observations. The Odin/SMR and Aura/MLS N2O observations also show a quasi

  12. Stratospheric lifetimes of CFC-12, CCl4, CH4, CH3Cl and N2O from measurements made by the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS

    Directory of Open Access Journals (Sweden)

    A. T. Brown

    2013-07-01

    Full Text Available Long lived halogen-containing compounds are important atmospheric constituents since they can act both as a source of chlorine radicals, which go on to catalyse ozone loss, and as powerful greenhouse gases. The long-term impact of these species on the ozone layer is dependent on their stratospheric lifetimes. Using observations from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS we present calculations of the stratospheric lifetimes of CFC-12, CCl4, CH4, CH3Cl and N2O. The lifetimes were calculated using the slope of the tracer–tracer correlation of these species with CFC-11 at the tropopause. The correlation slopes were corrected for the changing atmospheric concentrations of each species based on age of air and CFC-11 measurements from samples taken aboard the Geophysica aircraft – along with the effective linear trend of the volume mixing ratio (VMR from tropical ground based AGAGE (Advanced Global Atmospheric Gases Experiment sites. Stratospheric lifetimes were calculated using a CFC-11 lifetime of 45 yr. These calculations produced values of 113 + (− 26 (18 yr (CFC-12, 35 + (− 11 (7 yr (CCl4, 69 + (− 65 (23 yr (CH3Cl, 123 + (− 53 (28 yr (N2O and 195 + (− 75 (42 yr (CH4. The errors on these values are the weighted 1σ non-systematic errors. Systematic errors were estimated by recalculating lifetimes using VMRs which had been modified to reflect differences between ACE-FTS retrieved VMRs and those from other instruments. The results of these calculations, including systematic errors, were as follows: 113 + (− 32 (20 for CFC-12, 123 + (− 83 (35 for N2O, 195 + (− 139 (57 for CH4, 35 + (− 14 (8 for CCl4 and 69 + (− 2119 (34 yr for CH3Cl. For CH3Cl & CH4 this represents the first calculation of the stratospheric lifetime using data from a space based instrument.

  13. Effect of water addition and nitrogen fertilization on the fluxes of CH4, CO2, NOx, and N2O following five years of elevated CO2 in the Colorado Shortgrass Steppe

    Directory of Open Access Journals (Sweden)

    A. R. Mosier

    2003-01-01

    Full Text Available An open-top-chamber (OTC CO2 enrichment (~720 mmol mol-1 study was conducted in the Colorado shortgrass steppe from April 1997 through October 2001. Aboveground plant biomass increased under elevated CO2 and soil moisture content was typically higher than under ambient CO2 conditions. Fluxes of CH4, CO2, NOx and N2O, measured weekly year round were not significantly altered by CO2 enrichment over the 55 month period of observation. During early summer of 2002, following the removal of the open-top-chambers from the CO2 enrichment sites in October 2001, we conducted a short term study to determine if soil microbial processes were altered in soils that had been exposed to double ambient CO2 concentrations during the growing season for the past five years. Microplots were established within each experimental site and 10 mm of water or 10 mm of water containing the equivalent of 10 g m-2 of ammonium nitrate-N was applied to the soil surface. Fluxes of CO2, CH4, NOx and N2O fluxes within control (unchambered, ambient CO2 and elevated CO2 OTC soils were measured at one to three day intervals for the next month. With water addition alone, CO2 and NO emission did not differ between ambient and elevated CO2 soils, while CH4 uptake rates were higher and N2O fluxes lower in elevated CO2 soils. Adding water and mineral N resulted in increased CO2 emissions, increased CH4 uptake and decreased NO emissions in elevated CO2 soils. The N addition study confirmed previous observations that soil respiration is enhanced under elevated CO2 and N immobilization is increased, thereby decreasing NO emission.

  14. Air-Sea Interactions of Natural Long-Lived Greenhouse Gases (CO2, N2O, CH4) in a Changing Climate

    Digital Repository Service at National Institute of Oceanography (India)

    Bakker, D.C.E.; Bange, H.W.; Gruber, N.; Johannessen, T.; Upstill-Goddard, R.C.; Borges, A.V.; Delille, B.; Loscher, C.R.; Naqvi, S.W.A.; Omar, A.M.; Santana-Casiano, J.M.

    pre-industrially to 389 ppm in 2010 (Forster et al. 2007; WDCGG 2012). Changes in ocean circulation and biology and the feedbacks between them have been invoked to explain the glacial/ interglacial fluctuations of tropospheric CO2 but under- standing... positive carbon-climate feedbacks. Today the situation is fundamentally different in that the increasing greenhouse gas content drives changes in climate and environment. Variation in stratospheric N2O between 200 and 280 ppb during the past 650,000 years...

  15. A preliminary study of carbon dioxide,methane and nitrous oxide fluxes from the Gahai wetland%尕海湿地 CH4、CO2和 N2O 通量特征初步研究

    Institute of Scientific and Technical Information of China (English)

    马维伟; 王辉; 李广; 赵锦梅; 王跃思

    2015-01-01

    A study has been undertaken to estimate fluxes of the greenhouse gases carbon dioxide (CO2 ),meth-ane (CH4 )and nitrous oxide (N2 O)in wetlands,to understand the effects of temperature factors on these processes and to estimate global warming potential (GWP).Using static chamber techniques,we measured CH4 ,CO2 ,and N2 O fluxes from four wetland types in Gansu Gahai Wetlands,China,from July 2011 to July 2012.The results showed high variations in CH4 ,CO2 and N2 O fluxes between the four wetlands,with the smallest values in the subalpine meadow (-0.014 ±0.126 mg/m2 ·h),marsh wetland (137.17 ±284.51 mg/m2 ·h)and mountain wetland (-0.008 ±0.022 mg/m2 ·h)respectively.The highest values of CH4 , CO2 and N2 O fluxes were in marsh wetland (0.498±0.682 mg/m2 ·h),mountain wetland (497.81 ±473.09 mg/m2 ·h)and herbaceous peat (0.094±0.117 mg/m2 ·h)respectively.CH4 and CO2 fluxes varied seasonal- ly.Maximal fluxes occurred between July-October 2011 and May-July 2012,then decreased and remained relatively steady,with some slight fluctuations during the winter and thawing or freezing periods.Further a-nalysis showed that air temperature,soil temperature (at 5 cm),surface temperature and temperature inside the box were highly significantly positively correlated with CO2 flux from the four wetlands.These variables were significantly positively correlated with CH4 flux from mountain wetland but not from the other wetland types.They were significantly negatively correlated with N2 O flux from all four wetland types.The GWP esti-mates were 35.311,13.520,34.816 and 30.236 t CO2/(hm2 · a)from herbaceous peat,marsh wetland, mountain wetland and subalpine meadow respectively.These results show that marsh wetland could signifi-cantly decrease the emission of greenhouse gases from the Gahai Wetlands.%2011年7月-2012年7月,采用静态箱-气相色谱法同步研究了尕海4种典型湿地类型的 CH4、CO2和N2 O 通量及其与温度因子的关系,并估算了其

  16. Short-term Effects of Saltwater Intrusion and Organic Carbon Loading on CH4 and N2 O Flux from Estuarine Freshwater Marsh Ecosystem%盐水入侵及有机碳输入对河口淡水沼泽CH4、 N2O通量影响的短时效应

    Institute of Scientific and Technical Information of China (English)

    张璟钰; 章吟遥; 仝川; 李琼; 王纯

    2016-01-01

    为了探究盐水入侵及外源有机碳输入对河口潮汐淡水沼泽湿地生态系统甲烷( CH4)和氧化亚氮( N2 O)通量的影响,运用中型实验生态系模拟法,通过添加人造海水和醋酸盐,结合气相色谱测定,对闽江河口短叶茳芏( Cyperus malaccensis )潮汐淡水沼泽湿地生态系统CH4和N2 O通量进行测定与分析。结果表明:1)盐分输入在短时内(24 h )显著抑制湿地CH4排放通量(P<0.05),有机碳输入显著促进CH4排放通量(P<0.05),盐水入侵耦合有机碳输入对CH4排放无显著影响。2)盐分输入、有机碳输入及两者的耦合作用在短时内(24 h)对湿地N2 O通量无显著影响。3)4种处理形式综合作用下,湿地CH4排放通量与土壤电导率显著负相关(P<0.05), N2O通量与土壤pH表现为显著正相关(P<0.05),与土壤Eh显著负相关(P<0.05)。4)短时内各添加处理对CH4和N2O综合增温潜势无显著影响。%According to the mesocosm simulated experiments method, by adding artificial seawater and acetate, combined with gas chromatography determination, we explored short-term effects of salt water intrusion and exogenous organic carbon input on the methane ( CH4 ) and Nitrous Oxide ( N2 O) flux from the ecosystem of Cyperus malaccensis tidal freshwater marsh wetland in Min River estuary. Results show that : 1) the salt input significantly inhibited the CH4 emission flux in a short time (24 h) (P<0. 05), organic carbon input significantly promoted the CH4 emission flux (P<0. 05), the inputs of saltwater intrusion coupled organic carbon had no significant effect on the emission flux of CH4 . 2) The N2 O emission flux was not significantly changed by the inputs of the salt, organic carbon and saltwater intrusion coupled organic carbon in a short time (24 h). 3) The CH4 emission flux was significantly neg-ative correlation with soil conductivity (P<0. 05), the N2O emission flux as significantly positive corre

  17. Measurement of N2O and CH4 soil fluxes from garden, agricultural and natural soils using both closed and open chamber systems coupled with high-precision CRDS analyzer

    Science.gov (United States)

    He, Yonggang; Jacobson, Gloria; Alexander, Chris; Fleck, Derek; Hoffnagel, John; Del Campo, Bernardo; Rella, Chris

    2013-04-01

    Studying the emission and uptake of greenhouse gases from soil is essential for understanding, adapting to and ultimately mitigating the effects of climate change. To-date, majority of such studies have been focused on carbon dioxide (CO2 ) , however, in 2006 the EPA estimated that "Agricultural activities currently generate the largest share, 63 percent, of the world's anthropogenic non-carbon dioxide (non-CO2) emissions (84 percent of nitrous oxide [N2O] and 52 percent of methane[CH4]), and make up roughly 15 percent of all anthropogenic greenhouse gas emissions" (Prentice et al., 2001). Therefore, enabling accurate N2O and CH4 flux measurements in the field are clearly critical to our ability to better constrain carbon and nitrogen budgets, characterize soil sensitivities, agricultural practices, and microbial processes like denitrification and nitrification. To aide in these studies, Picarro has developed a new analyzer based on its proven, NIR technology platform, which is capable of measuring both N2O and CH4 down to ppb levels in a single, field-deployable analyzer. This analyzer measures N2O with a 1-sigma, precision of 3.5 ppb and CH4 with a 1-sigma precision of 3ppb on a 5 minute average. The instrument also has extremely low drift to enable accurate measurements with infrequent calibrations. The data rate of the analyzer is on the order of 5 seconds in order to capture fast, episodic emission events. One of the keys to making accurate CRDS measurements is to thoroughly characterize and correct for spectral interfering species. This is especially important for closed system soil chambers used on agricultural soils where a variety of soil amendments may be applied and gases not usually present in ambient air could concentrate to high levels. In this work, we present the results of analyzer interference testing and corrections completed for the interference of carbon dioxide, methane, ammonia, ethane, ethylene, acetylene, and water on N2O. In addition, we

  18. Impact of elevated CO2 and temperature on soil C and N dynamics in relation to CH4 and N2O emissions from tropical flooded rice (Oryza sativa L.).

    Science.gov (United States)

    Bhattacharyya, P; Roy, K S; Neogi, S; Dash, P K; Nayak, A K; Mohanty, S; Baig, M J; Sarkar, R K; Rao, K S

    2013-09-01

    A field experiment was carried out to investigate the impact of elevated carbon dioxide (CO2) (CEC, 550 μmol mol(-1)) and elevated CO2+elevated air temperature (CECT, 550 μmol mol(-1) and 2°C more than control chamber (CC)) on soil labile carbon (C) and nitrogen (N) pools, microbial populations and enzymatic activities in relation to emissions of methane (CH4) and nitrous oxide (N2O) in a flooded alluvial soil planted with rice cv. Naveen in open top chambers (OTCs). The labile soil C pools, namely microbial biomass C, readily mineralizable C, water soluble carbohydrate C and potassium permanganate oxidizable C were increased by 27, 23, 38 and 37% respectively under CEC than CC (ambient CO2, 394 μmol mol(-1)). The total organic carbon (TOC) in root exudates was 28.9% higher under CEC than CC. The labile N fractions were also increased significantly (29%) in CEC than CC. Methanogens and denitrifier populations in rhizosphere were higher under CEC and CECT. As a result, CH4 and N2O-N emissions were enhanced by 26 and 24.6% respectively, under CEC in comparison to open field (UC, ambient CO2, 394 μmol mol(-1)) on seasonal basis. The global warming potential (GWP) was increased by 25% under CEC than CC. However, emissions per unit of grain yield under elevated CO2 and temperature were similar to those observed at ambient CO2. The stimulatory effect on CH4 and N2O emissions under CEC was linked with the increased amount of soil labile C, C rich root exudates, lowered Eh, higher Fe(+2) concentration and increased activities of methanogens and extracellular enzymes.

  19. Comparison of CMAM simulations of carbon monoxide (CO, nitrous oxide (N2O, and methane (CH4 with observations from Odin/SMR, ACE-FTS, and Aura/MLS

    Directory of Open Access Journals (Sweden)

    B. Barret

    2008-07-01

    Full Text Available Simulations of CO, N2O and CH4 from a coupled chemistry-climate model (CMAM are compared with satellite measurements from Odin Sub-Millimeter Radiometer (Odin/SMR, Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS, and Aura Microwave Limb Sounder (Aura/MLS. Pressure-latitude cross-sections and seasonal time series demonstrate that CMAM reproduces the observed global distributions and the polar winter time evolutions of the CO, N2O, and CH4 measurements quite well. Generally, excellent agreement with measurements is found in CO monthly zonal mean profiles in the stratosphere and mesosphere for various latitudes and seasons. The difference between the simulations and the observations are generally within 30%, which is comparable with the difference between the instruments in the upper stratosphere and mesosphere. In general, the CO measurements also show an excellent agreement between themselves although MLS retrievals are noisier than other retrievals above 10 hPa (~32 km. The measurements also show large difference in the lower stratosphere and upper troposphere. Comparisons of N2O show that CMAM results usually have a less than 15% difference to the measurements in the lower and middle stratosphere, and the observations are consistent as well. However, the standard version of CMAM has a serious low bias in the upper stratosphere. The CMAM CH4 distribution is also close to the observations in the lower stratosphere, but has a similar but smaller negative bias in the upper stratosphere. These negative biases can be reduced by introducing a vertical diffusion coefficient related to gravity wave drag. CO measurements from 2004 and 2006 show evidence of enhanced descent of air from the mesosphere into the stratosphere in the Arctic after strong stratospheric sudden warmings (SSWs. CMAM also shows strong descent of air after SSWs, but further investigation is needed. In the tropics, CMAM captures the "tape recorder" (or annual

  20. NH and OH Concentration Profiles in a Stoichiometric CH4/N2O Flame by Laser Excited Fluorescence and Absorption Techniques.

    Science.gov (United States)

    1982-10-01

    Molecular Beam Mass Spectrometry and Ultraviolet Absorption Spectroscopy, Combustion and Flane VoZ . 33, p. 5, 1978. 2 CattoZica, R.J., Yoon, S. and Knuth, E.L...National Bureau of Standards Special Publication 561/2, U.S. Government Printing Office, ’-..Washington, D.C., VoZ . II, Section VI, 1979. ?Anderson, W.R...Chm. Phys. VoZ . 43, p. 3237, 1965. 19 1Anderson, W.R., Decker, L.J., and KotZar, A.J., "Concentration Profiles of NH and OH in a Stoichiometric CH4

  1. A new method to detect long term trends of methane (CH4 and nitrous oxide (N2O total columns measured within the NDACC ground-based high resolution solar FTIR network

    Directory of Open Access Journals (Sweden)

    M. Schneider

    2011-07-01

    Full Text Available Total columns measured with the ground-based solar FTIR technique are highly variable in time due to atmospheric chemistry and dynamics in the atmosphere above the measurement station. In this paper, a multiple regression model with anomalies of air pressure, total columns of hydrogen fluoride (HF and carbon monoxide (CO and tropopause height are used to reduce the variability in the methane (CH4 and nitrous oxide (N2O total columns to estimate reliable linear trends with as small uncertainties as possible. The method is developed at the Harestua station (60° N, 11° E, 600 m a.s.l. and used on three other European FTIR stations, i.e. Jungfraujoch (47° N, 8° E, 3600 m a.s.l., Zugspitze (47° N, 11° E, 3000 m a.s.l., and Kiruna (68° N, 20° E, 400 m a.s.l.. Linear CH4 trends between 0.13 ± 0.01-0.25 ± 0.02 % yr−1 were estimated for all stations in the 1996-2009 period. A piecewise model with three separate linear trends, connected at change points, was used to estimate the short term fluctuations in the CH4 total columns. This model shows a growth in 1996–1999 followed by a period of steady state until 2007. From 2007 until 2009 the atmospheric CH4 amount increases between 0.57 ± 0.22–1.15 ± 0.17 % yr−1. Linear N2O trends between 0.19 ± 0.01–0.40 ± 0.02 % yr−1 were estimated for all stations in the 1996-2007 period, here with the strongest trend at Harestua and Kiruna and the lowest at the Alp stations. From the N2O total columns crude tropospheric and stratospheric partial columns were derived, indicating that the observed difference in the N2O trends between the FTIR sites is of stratospheric origin. This agrees well with the N2O measurements by the SMR instrument onboard the Odin satellite showing the highest trends at Harestua, 0.98 ± 0.28 % yr−1, and considerably smaller trends at lower latitudes, 0.27 ± 0.25 % yr−1. The multiple regression model was compared with two other trend methods, the ordinary linear

  2. Stratospheric lifetimes of CFC-12, CCl4, CH4, CH3Cl and N2O from measurements made by the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS

    Directory of Open Access Journals (Sweden)

    P. F. Bernath

    2013-02-01

    Full Text Available Long lived halogen-containing compounds are important atmospheric constituents since they can act both as a source of chlorine radicals, which go on to catalyse ozone loss, and as powerful greenhouse gases. The long term impact of these species on the ozone layer is dependent on their stratospheric lifetimes. Using observations from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS we present calculations of the stratospheric lifetimes of CFC-12, CCl4, CH4, CH3Cl and N2O. The lifetimes were calculated using the slope of the tracer-tracer correlation of these species with CFC-11 at the tropopause. The correlation slopes were corrected for the changing atmospheric concentrations of each species based on age of air and CFC-11 measurements from samples taken aboard the Geophysica aircraft – along with the effective linear trend of the VMR from tropical ground-based AGAGE sites. Stratospheric lifetimes were calculated using a CFC-11 lifetime of 45 yr. These calculations produced values of 113 + (− 26 (18 yr (CFC-12, 35 + (− 11 (7 yr (CCl4, 195 + (− 75 (42 yr (CH4, 69 + (− 65 (23 yr (CH3Cl and 123 + (− 53 (28 yr (N2O. The errors on these values are the weighted 1-σ non-systematic errors. The stratospheric lifetime of CH3Cl represents the first calculations of the stratospheric lifetime of CH3Cl using data from a space based instrument.

  3. HIAPER Pole-to-Pole Observations (HIPPO): Global distributions and emission sources for CH4, N2O, Black Carbon, and other trace species inferred from five aircraft missions

    Science.gov (United States)

    Wofsy, S. C.; Hippo Science Team

    2011-12-01

    The HIAPER Pole-to-Pole Observations (HIPPO) program carried out five aircraft transects spanning the Pacific latitutdes from 85N to 67S, with vertical profiles every approximately 2.2 of latitude. Measurements included greenhouse gases, long-lived tracers, reactive species, O2/N2 ratio, black carbon (BC), aerosols, and CO2 isotopes. We found that the atmosphere maintains strong concentration gradients at air mass boundaries, especially at jet streams and major persistent frontal zones such as the South Pacific Convergence Zone and ITCZ. For some species (e.g. CH4) the strongest gradients were across the northern polar jet stream, while others (e.g. Black Carbon) showed more of an interhemispheric gradient. In the tropics, we observed excess concentrations of tracers such as N2O distributed broadly through the upper troposphere. These different patterns reflect the influences of sources and sinks, providing new constraints on global emissions and transport processes. Tropical land emissions appear to dominate for N2O, and emissions from both the polar ocean and Arctic lands strengthen gradients of CH4 in the Arctic. High altitudes in the Arctic were coupled to the surface at midlatitudes, as shown by propagation of seasonal signals and transport of pollutants, reflecting the influence of isentropic transport. This transport process has a major influence on the vertical distribution of atmospheric CO2, with potentially significant impact on inverse analyses of the global carbon cycle. Other notable features of the data will be surveyed in this paper.

  4. Relationships between the potential production of the greenhouse gases CO2, CH4 and N2O and soil concentrations of C, N and P across 26 paddy fields in southeastern China

    Science.gov (United States)

    Wang, Weiqi; Sardans, Jordi; Wang, Chun; Zeng, Congsheng; Tong, Chuan; Asensio, Dolores; Peñuelas, Josep

    2017-09-01

    Paddy fields are a major global anthropogenic source of greenhouse gases. China has the second largest area under rice cultivation, so determining the relationships between the emission of greenhouse gases and soil carbon content, nutrient availabilities and concentrations and physical properties is crucial for minimizing the climatic impacts of rice agriculture. We examined soil nutrients and other properties, greenhouse-gas production and their relationships in 26 paddy fields throughout the province of Fujian in China, one of the most important provinces for rice production. High P and K concentrations, contents and availabilities were correlated with low rates of CO2 production, whereas high C and N contents were correlated with high rates of CH4 production. Mean annual precipitation (MAP) and rates of gas production were not clearly correlated, at least partly due to the management of flooding that can mask the effect of precipitation. Higher mean annual temperatures and soil Fe contents favored the production of N2O. C, N, P and K concentrations and their ratios, especially the C:K and N:K ratios, and P availability were correlated with CO2 and CH4 production across the province, with higher C:K and N:K ratios correlated positively with increased CO2 production and available P correlated negatively with CH4 production. A management strategy to avoid excessive C accumulation in the soil and to increase P availability and decrease available Fe contents would likely decrease the production of greenhouse gases.

  5. How well can we assess impacts of agricultural land management changes on the total greenhouse gas balance (CO2, CH4 and N2O) of tropical rice-cropping systems with biogeochemical models?

    Science.gov (United States)

    Kraus, David; Weller, Sebastian; Janz, Baldur; Klatt, Steffen; Santabárbara, Ignacio; Haas, Edwin; Werner, Christian; Wassmann, Reiner; Kiese, Ralf; Butterbach-Bahl, Klaus

    2016-04-01

    Paddy rice cultivation is increasingly challenged by physical and economic irrigation water scarcity. This already results in the trend of converting paddy rice to upland crop cultivation (e.g., maize, aerobic rice) in large parts of South East Asia. Such land management change from flooded lowland systems to well-aerated upland systems drastically affects soil C and N cycling and related emissions of greenhouse gases. Emissions of methane (CH4) are expected to decrease, while emissions of nitrous oxide (N2O) will most likely increase. In addition to such fast evolving 'pollution swapping' it is expected that on longer time scales significant amounts of soil organic carbon (SOC) stocks will be lost in form of carbon dioxide (CO2). Within the DFG-funded research unit ICON (Introducing non-flooded crops in rice-dominated landscapes: Impact on carbon, nitrogen and water cycles), we investigated environmental impacts of land management change from historical paddy rice cultivation to the upland crops maize and aerobic rice at experimental sites at the International Rice Research Institute (IRRI), the Philippines. To present, more than three years of continuous measurement data of CH4 and N2O emissions under different fertilization regimes have been collected. In addition, measurements of SOC contents and bulk densities in different soil horizons allow for an overall very good characterization of the environmental impacts of mentioned land management change. In this contribution we will show how well mentioned land management change effects in tropical agricultural systems can be represented and thus better understood by the help of process-based biogeochemical models. Seasonal emissions of CH4 and N2O are simulated with r2 values of 0.85 and 0.78 and average underestimations of 15 and 14 %, respectively. These underestimations predominantly originate from treatments in which no fertilizer is applied (CH4) as well as uncertainties of soil hydrology (N2O). Long

  6. 北极新奥尔松地区夏季近地面CO2、CH4和N2O浓度的观测研究%SPATIAL AND TEMPORAL VARIATIONS IN CO2, CH4 AND N2O CONCENTRATION IN NY-(A)LESUND, SVALBARD

    Institute of Scientific and Technical Information of China (English)

    陈清清; 朱仁斌; 徐华

    2013-01-01

    During the summers of 2008 and 2009,total 239 gas samples were collected using vacuum flask from the sites in different tundra areas,including bird sanctuary,beach tundra,mining area,human activity area,etc.in Ny-(A)lesund,Svalbard,Norway.The concentrations of carbon dioxide (CO2),methane (CH4) and nitrous oxide (N2O) in these gas samples were determined by gas chromatography in the laboratory,the spatial and temporal variations of their concentrations were analyzed,and the factors affecting their concentrations were also analyzed in this study.The diurnal mean CO2 and N2O concentrations in summer 2008 were about 30 ppm and 25 ppb higher than those in summer 2009 at the sites in the bird sanctuary.The mean CO2 concentration at the sites in beach tundra were 30 ppm higher in summer 2008 than in summer 2009 while the mean N2O concentration was 11 ppb lower in summer 2008 than in summer 2009.The CH4 concentration in summer 2008 was 0.7 ppm lower than that in summer 2009 at the bird sanctuary,vice versus for the sites in the beach tundra.These interannual variation of greenhouse gases concentrations might be related to environmental conditions.High seabird activity sites (HB) showed lower CO2 concentrations than medium and low seabird activity sites (MB and LB) in bird sanctuary.Overall the mean concentration of CO2 in the bird sanctuary was lower than that in the beach tundra,but higher N2O concentration occurred there,indicating that CO2 uptake and N2O emission might be associated with seabird activities.The deposition of seabird guano supplied much organic carbon,nitrogen into local soils,and further stimulated tundra vegetation growth,which might increase tundra CO2 sink and N2O emission.Overall the mean concentrations of CO2 and CH4 in Ny-(A)lesund were higher than the averages monitored in ZEP (Zeppelin Station),whereas the mean N2O concentration was lower than the average in ZEP.In addition,the mining area and human activity areas around the base and airport did

  7. 反刍家畜及其排泄物对N2O和CH4排放的贡献%Contributions of ruminants and their excreta to N2O and CH4 emissions

    Institute of Scientific and Technical Information of China (English)

    林巧燕; 布仁巴音; 汪诗平

    2011-01-01

    了解反刍动物及其排泄物对温室气体的贡献以及主要影响因素对于认识全球气候变化及寻找减缓措施都具有重要的社会、经济和生态学意义.本文在综述了大量国内外相关文献的基础上,提出提高家畜营养水平和均衡营养,特别是在天然草原上增加豆科牧草的比例,并通过在饲料中适量添加中链脂肪酸等添加剂,是提高家畜的生产性能、降低CH4排放量的有效措施.同时指出,由于在家畜排泄物处理和利用过程中,降低一种温室气体的排放可能会增加另一种气体的排放,因此,应该根据它们对大气增温潜值的差异,将各种处理下温室气体换算成CO2-C,从而进行比较分析,通过调整综合措施以达到二者总释放量的最低水平;同时还应该考虑到所产生的NH3和亚硝酸盐/硝酸盐对大气和环境的污染.因此,如何提高反刍家畜的饲养与营养、调整放牧管理制度、改善草原群落结构,从而在提高个体生产性能的基础上达到降低家畜总饲养量,最终实现草原生态保护、家畜生产和温室气体排放综合考虑的折衷管理方案,是今后所要解决的科学问题.任何减缓温室气体排放的措施都应该以整个生产系统为基础,从而综合评价所采取措施的有效性.%To clarify the contributions of ruminants and their excreta to greenhouse gases emission and the main affecting factors is of social, economic, and ecological significances for understanding the global climate change and searching for related mitigation options. Based on the related researches, it was considered that to improve the dietary quality and nutritional balance of ruminants (e. G. , to add additives medium-chain fatty acid and others into diets and to increase the proportions of leguminous grasses in grassland) could be the effective measures in enhancing ruminant productivity while decreasing CH4 emission. The contributions of ammonia, nitrite

  8. Effects of rice straw, biochar and mineral fertiliser on methane (CH4) and nitrous oxide (N2O) emissions from rice (Oryza sativa L.) grown in a rain-fed lowland rice soil of Cambodia

    DEFF Research Database (Denmark)

    Ly, Proyuth; Duong, Quynh Vu; Jensen, Lars Stoumann;

    2015-01-01

    accounted for on average 1.7 % of the total applied mineral fertiliser N. Overall, the global warming potentials (GWPs) were lower in treatments under AWD than those under the CF water regime except for the control treatment with only mineral fertiliser application. Grain yields were slightly higher......We studied the effects of water regimes and nutrient amendments on CH4 and N2O emissions in a 2 × 3 factorial, completely randomised growth chamber experiment. Treatments included continuously flooded (CF) and alternate wetting and drying (AWD), and three organic amendments: no amendment......-control, rice straw (RS) and biochar (BC). Compound fertiliser was applied to all treatments. Rice was grown in columns packed with a paddy soil from Cambodia. Results revealed faster mineralisation of organic carbon (RS and BC) when applied in water-saturated conditions lasting for 2 weeks instead of flooding...

  9. Seasonal and spatial variability of aquatic N2O, CH4 and CO2 concentrations and their contribution to the overall greenhouse gas budget of the river Tay catchment, NW Europe

    Science.gov (United States)

    Skiba, Ute; Harley, James; Carvalho, Laurence; Heal, Kate; Rees, Bob

    2016-04-01

    River networks act as a link between components of the terrestrial landscape with the atmosphere and oceans, and are believed to contribute significantly to global budgets of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). However, knowledge of flux magnitudes and drivers of seasonal and spatial variability required to understand their contribution to the overall catchment greenhouse (GHG) flux is only available for relatively few river systems. For this reason we conducted a two year study of monthly GHG concentration measurements from the river Tay. The river Tay is the largest river in Scotland, in terms of discharge and can be considered typical for many North European river systems. The Tay and its tributaries drain peat dominated uplands and agricultural lowlands before entering the North Sea via the large intertidal estuary. We collected water samples from 9 locations along the river monthly and analysed these sampes for dissolved concentrations of N2O, CH4 and CO2, NH4+ , NO3-, O2, total organic carbon and nitrogen, pH and turbidity. Fluxes across the air water interface were calculated using published gas transfer equations. All GHGs showed considerable spatial and seasonal variation. Nitrous oxide emissions ranged from 176 to 1850 μg N m-2 d-1 over the almost two year period February 2009 to December 2010. Emissions were highest in the lowland tributaries related to higher nutrient concentrations associated with more intensive agricultural activity. Methane emissions ranged from 1720 to 15500 μg C m-2 d-1, and in general decreased from upland to lowland sites. Variation in sediment quality was the predominant driving factor. Carbon dioxide emissions ranged from 517 to 2550 mg C m-2 d-1 and generally increased from upland to lowland sites. Emissions were highest in late summer and autumn and lowest in winter at most sites, highlighting the role of seasonal environmental controls such as temperature, light, and substrate availability

  10. Effect of Slow/Controlled Release Fertilizers on CH4 and N2O Emissions From Helianthus tuberosus Field on Tidal Flat During Growing Season%缓释氮肥对菊芋生长季土壤CH4和N2O排放的影响

    Institute of Scientific and Technical Information of China (English)

    王浩成; 陈楠楠; 周超; 张令; 刘树伟; 邹建文

    2012-01-01

    设置尿素+硝化抑制剂(U+ DCD)、尿素+脲酶抑制剂(U+HQ)、脲甲醛(UF)、钙镁磷肥包膜尿素(CM-CU)、树脂包膜尿素(PCU)、硫包尿素(SCU)6种缓释氮肥处理以及普通尿素(U)处理,在江苏大丰进行小区试验,采用静态箱-气相色谱法同步观测沿海滩涂能源植物——菊芋(Helianthus tuberosus)生长季土壤的CH4和N2O排放通量及其减排潜力.结果表明,在2010年整个菊芋生长季,U、PCU、UF、SCU、CMCU、U+HQ和U+DCD处理土壤CH4排放总量依次为1.25、0.59、0.43、0.27、0.25、0.26和-0.21 kg·hm-2.与普通尿素处理相比,除U+ DCD处理外,其余施用缓释氮肥处理可使CH4排放量减少53% ~ 80%.生长季PCU、SCU、CMCU、U、UF、U+HQ和U+DCD处理的N2O排放总量分别为2.94、2.44、2.27、2.24、1.77、1.47和1.34 kg·hm-2.与普通尿素处理相比,施用化学型缓释氮肥(U +DCD、U+HQ和UF处理)使N2O排放量减少21% ~ 40%,而施用物理型缓释氮肥(CM-CU、PCU和SCU处理)则使N2O排放量增加1%~31%.从全球增温潜势看,各化学型缓释氮肥处理均表现出显著的减排效果.%A field experiment, designed to have seven treatments, i. e. U + DCD (urea plus dicyandiamide) , U + HQ (urea plus hydroquinone) , UF (urea formaldehyde) , CMCU ( Ca-Mg-P-coated urea) , PCU (polymer-coated urea) , SCU ( sulfur-coated urea) and CK or U (urea) , was conducted to explore effects of some typical slow-release fertilizers on methane (CH4) and nitrous oxide ( N2O) emissions from Helianthus tuberosus fields on tidal flat in Dafeng of Jiangsu Province during its growing season in 2010. Fluxes of CH4 and N2O emissions from the field were measured simultaneously with static chamber-GC method. Results show that in terms of seasonal CH4 emission, the 7 treatments followed the order of U > PCU > UF > SCU > CMCU > U + HQ > U + DCD, emitting 1. 25 , 0. 59, 0. 43 , 0. 27, 0. 25, 0. 26 and - 0. 21 kg ? hm-2, respectively. Compared with urea, the

  11. Consistency and quality assessment of the Metop-A/IASI and Metop-B/IASI operational trace gas products (O3, CO, N2O, CH4, and CO2) in the subtropical North Atlantic

    Science.gov (United States)

    García, Omaira Elena; Sepúlveda, Eliezer; Schneider, Matthias; Hase, Frank; August, Thomas; Blumenstock, Thomas; Kühl, Sven; Munro, Rosemary; Jesús Gómez-Peláez, Ángel; Hultberg, Tim; Redondas, Alberto; Barthlott, Sabine; Wiegele, Andreas; González, Yenny; Sanromá, Esther

    2016-05-01

    This paper presents the tools and methodology for performing a routine comprehensive monitoring of consistency and quality of IASI (Infrared Atmospheric Sounding Interferometer) trace gas Level 2 (L2) products (O3, CO, N2O, CH4, and CO2) generated at EUMETSAT (European Organisation for the Exploitation of Meteorological Satellites) using ground-based observations at the Izaña Atmospheric Observatory (IZO, Tenerife). As a demonstration the period 2010-2014 was analysed, covering the version 5 of the IASI L2 processor. Firstly, we assess the consistency between the total column (TC) observations from the IASI sensors on board the EUMETSAT Metop-A and Metop-B meteorological satellites (IASI-A and IASI-B respectively) in the subtropical North Atlantic region during the first 2 years of IASI-B operations (2012-2014). By analysing different timescales, we probe the daily and annual consistency of the variability observed by IASI-A and IASI-B and thereby assess the suitability of IASI-B for continuation of the IASI-A time series. The continuous intercomparison of both IASI sensors also offers important diagnostics for identifying inconsistencies between the data records and for documenting their temporal stability. Once the consistency of IASI sensors is documented we estimate the overall accuracy of all the IASI trace gas TC products by comparing to coincident ground-based Fourier transform infrared spectrometer (FTS) measurements performed at IZO from 2010 to 2014. The IASI L2 products reproduce the ground-based FTS observations well at the longest temporal scales, i.e. annual cycles and long-term trends for all the trace gases considered (Pearson correlation coefficient, R, larger than 0.95 and 0.75 for long-term trends and annual cycles respectively) with the exception of CO2. For CO2 acceptable agreement is only achieved for long-term trends (R ˜ 0.70). The differences observed between IASI and FTS observations can be in part attributed to the different vertical

  12. Vehicle emissions of greenhouse gases and related tracers from a tunnel study: : CO: CO2, N2O: CO2, CH4: CO2, O2: CO2 ratios, and the stable isotopes 13C and 18O in CO2 and CO

    National Research Council Canada - National Science Library

    Popa, Maria Elena; Vollmer, M. K; Jordan, A; Brand, W. A; Pathirana, S. L; Rothe, M; Röckmann, T

    2014-01-01

    Measurements of CO2, CO, N2O and CH4 mole fractions, O2/N2 ratios and the stable isotopes 13C and 18O in CO2 and CO have been performed in air samples from the Islisberg highway tunnel (Switzerland). The molar CO...

  13. The controlling factors and coupling of soil CO2, CH4 and N2O fluxes in a temperate needle-broadleaved mixed forest%温带针阔混交林土壤碳氮气体通量的主控因子与耦合关系

    Institute of Scientific and Technical Information of China (English)

    党旭升; 李林森; 王磊; 程淑兰; 方华军; 于贵瑞; 韩士杰; 张军辉; 王淼; 王永生; 徐敏杰

    2015-01-01

    Carbon dioxide ( CO2 ) , methane ( CH4 ) and nitrous oxide ( N2 O) are three major greenhouse gases, accounting for 80% of global warming. Forest ecosystems comprise the largest carbon stocks in terrestrial ecosystems, and function as important sinks and sources of atmospheric CO2 , CH4 and N2 O. Complicated interactions occur during the generation and absorption of soil CO2 , CH4 and N2 O, including synergies, tradeoffs, and randomness. High-latitude forests are experiencing the effects of significant global change ( e. g., warming, changed precipitation, and increased nitrogen deposition) , leading to great uncertainty in estimates of soil greenhouse gas fluxes. Furthermore, the factors controlling the coupling of soil CO2 , CH4 and N2 O fluxes remain unclear. This study was conducted in the temperate needle-broadleaved mixed forest of Changbai Mountain, Northeast China. The net exchange fluxes of soil CO2 , CH4 and N2 O, as well as soil temperature and soil moisture, were measured over four years (2005–2009) using static chamber and gas chromatograph techniques. The results showed that temperate needle-broadleaved mixed forest soils behaved as a source of atmospheric CO2 and N2 O but a sink of atmospheric CH4 over the course of the study. The average soil CH4 , CO2 and N2 O fluxes were estimated at -1.30 kg CH4 hm-2 a-1 , 15102.2 kg CO2 hm-2 a-1 , and 6.13 kg N2 O hm-2 a-1 , respectively. In addition, soil CO2 flux exhibited significant seasonality, and was mainly affected by soil temperature, followed by soil moisture. Seasonal variation in soil CH4 flux was less significant than that of soil CO2 and N2 O fluxes; moreover, it was positively correlated with soil moisture. When soil temperatures were within a threshold range, soil moisture determined CH4 production and oxidation in soil profiles by regulating CH4 and O2 diffusion as well as methanotrophic community activity. Similar to soil CO2 flux, soil N2 O flux was significantly correlated with soil

  14. Effect of Carbon Substrate Concentration on N2, N2 O, NO, CO2 and CH4 Emissions from a Paddy Soil in Anaerobic Condition%碳底物含量对厌氧条件下水稻土N2、N2O、NO、CO2和CH4排放的影响

    Institute of Scientific and Technical Information of China (English)

    陈诺; 廖婷婷; 王睿; 郑循华; 胡荣桂; Klaus Butterbach-Bahl

    2014-01-01

    理解底物碳氮对厌氧条件下水稻土排放氮素气体---氮气( N2)、氧化亚氮( N2 O)和一氧化氮( NO)以及二氧化碳( CO2)和甲烷( CH4)的影响,有助于制定合理的温室气体减排措施,定量了解反硝化产物组成对碳底物水平的依赖性,也有助于氮转化过程模型研发中制定正确的关键过程参数选取方法或参数化方案.本研究采用粉砂壤质水稻土为研究对象,设置对照( CK)和加碳( C+)两个处理,前者的初始硝态氮和可溶性有机碳( DOC)含量分别为~50 mg•kg-1和~28 mg•kg-1,后者的分别为~50 mg•kg-1和~300 mg•kg-1.采用氦环境培养-气体及碳氮底物直接同步测定系统,研究了完全厌氧条件下碳底物水平对上述气体排放的影响.结果表明,CK处理无CH4排放,而C+处理可观测到CH4排放;C+处理的综合增温潜势显著高于CK处理( P﹤0.01);NO、N2 O和N2排放量占这3种氮素气体排放总量的比重,在CK处理分别约为9℅、35℅和56℅,在C+处理分别约为31℅、50℅和19℅,处理间差异显著(P﹤0.01).由此表明,碳底物水平可显著改变所排放氮素气体的组成;对于旱地阶段硝态氮比较丰富的水稻土,避免在淹水前或淹水期间施用有机肥,有利于削减温室气体排放.%Understanding the effects of carbon and nitrogen substrates concentrations on the emissions of denitrification gases including nitrogen ( N2 ) , nitrous oxide ( N2 O) and nitric oxide ( NO) , carbon dioxide ( CO2 ) and methane ( CH4 ) from anaerobic paddy soils is believed to be helpful for development of greenhouse gas mitigation strategies. Moreover, understanding the quantitative dependence of denitrification products compositions on carbon substrate concentration could provide some key parameters or parameterization scheme for developing process-oriented model( s) of nitrogen transformation. Using a silt loam soil collected from a paddy field, we investigated the influence of carbon

  15. Vehicle emissions of greenhouse gases and related tracers from a tunnel study: : CO: CO2, N2O: CO2, CH4: CO2, O2: CO2 ratios, and the stable isotopes 13C and 18O in CO2 and CO

    NARCIS (Netherlands)

    Popa, Maria Elena; Vollmer, M. K.; Jordan, A.; Brand, W. A.; Pathirana, S. L.|info:eu-repo/dai/nl/330541242; Rothe, M.; Röckmann, T.|info:eu-repo/dai/nl/304838233

    2014-01-01

    Measurements of CO2, CO, N2O and CH4 mole fractions, O2/N2 ratios and the stable isotopes 13C and 18O in CO2 and CO have been performed in air samples from the Islisberg highway tunnel (Switzerland). The molar CO : CO2 ratios, with an average of (4.15 ± 0.34) ppb:ppm, are lower than reported in prev

  16. Vehicle emissions of greenhouse gases and related tracers from a tunnel study: : CO: CO2, N2O: CO2, CH4: CO2, O2: CO2 ratios, and the stable isotopes 13C and 18O in CO2 and CO

    NARCIS (Netherlands)

    Popa, Maria Elena; Vollmer, M. K.; Jordan, A.; Brand, W. A.; Pathirana, S. L.; Rothe, M.; Röckmann, T.

    2014-01-01

    Measurements of CO2, CO, N2O and CH4 mole fractions, O2/N2 ratios and the stable isotopes 13C and 18O in CO2 and CO have been performed in air samples from the Islisberg highway tunnel (Switzerland). The molar CO : CO2 ratios, with an average of (4.15 ± 0.34) ppb:ppm, are lower than reported in prev

  17. Effect of bulking agent on CH4, N2O and NH3 emissions in kitchen waste composting%膨松剂对厨余垃圾堆肥CH4、N2O和NH3排放的影响

    Institute of Scientific and Technical Information of China (English)

    杨帆; 欧阳喜辉; 李国学; 罗文海; 杨青原

    2013-01-01

    厨余垃圾有别于混合生活垃圾,具有高有机质含量和高含水率等特点,单独堆肥会产生大量CH4、N2O、NH3和渗滤液,为减少厨余垃圾堆肥过程污染物的排放,该文以居民小区产生的经大类粗分后的厨余垃圾为研究对象,以菌糠为膨松剂,设置15%、25%、35%3个添加质量比(湿基)的堆肥处理,以纯厨余垃圾单独堆肥为对照处理,研究菌糠作为膨松剂对厨余垃圾堆肥过程中CH4、N2O、NH3和渗滤液排放的影响及其最佳添加比例。结果表明,堆肥过程中,添加菌糠可以完全避免厨余垃圾堆肥过程中渗滤液的产生;堆肥结束时,添加15%和25%菌糠的处理堆肥达到腐熟标准,但添加35%的菌糠使堆肥高温期缩短,不利于有机质分解;与对照处理相比,添加15%、25%和35%比例的菌糠均可以减少堆肥过程中CH4和NH3的累计排放量,且减排量与添加比例正相关,但只有添加15%菌糠的堆肥处理明显降低了 N2O 的排放量;添加质量比为15%和25%菌糠的堆肥处理,CH4和N2O排放总量比厨余垃圾单独堆肥分别减少45.8%、19.6%,而添加质量比为35%的菌糠使CH4和N2O排放总量为厨余垃圾单独堆肥的1.14倍(每t物料,干基)。综上,菌糠作为食用菌种植废弃物,可用作厨余垃圾堆肥膨松剂,在适宜的添加比例条件下,能够在避免堆肥过程中渗滤液产生的同时,减少CH4、N2O和NH3的排放量。研究结果可为厨余垃圾堆肥过程温室气体减排、氮素损失控制和工艺改进提供理论依据和试验基础。%Composting is a biological process which can reduce the volume and mass of organic waste, as well as produce a safe, stabilized, and nutrient enriched soil amendment. In recent years, composting has been widely used in handling kitchen waste. However, kitchen waste is different from mixed municipal solid waste, which has the characteristics of high

  18. 氢醌、双氰胺组合影响稻田甲烷和氧化亚氮排放研究进展%EFFECT OF COMBINED USE OF HYDROQUINONE AND DICYANDIAMIDE ON CH4 AND N2O EMISSIONS FROM RICE PADDY FIELD: A REVIEW

    Institute of Scientific and Technical Information of China (English)

    李香兰; 徐华; 蔡祖聪

    2009-01-01

    稻田是大气中CH_4和N_2O的重要来源.大量氮肥的施入不仅影响稻田CH_4和N2_O排放,且易造成NH3挥发、NO~-_2和NO~-_3淋溶及N_2O、N_2等形式的氮损失.脲酶抑制剂和硝化抑制剂通过缓解尿素水解及抑制硝化反硝化反应减少稻田N_2O排放量,但对稻田CH_4产生排放的影响报道不一.脲酶抑制剂氢醌(HQ)和硝化抑制剂双氰胺(DCD)是近年来研究较多的组合.本文试图在前人研究的基础上,综述HQ和DCD的基本性质及作用机理,总结HQ/DCD组合在稻田生态系统的应用状况、使用效果及存在问题,并特别讨论了HQ/DCD施用对稻田CH4排放的影响机理,旨在为合理使用脲酶/硝化抑制剂、有效减缓稻田温室气体排放和提高氮肥利用率等方面提供理论依据.%Rice paddy field is an important source of CH_4 and N_2O emissions to the atmosphere. Not only does application of nitrogen fertilizer affect CH_4 and N_2O emissions, but also lead to NH_3 volatilization, NO~-_2 and NO~-_3 leaching and N loss in the form of N_2O and N_2. The addition of urease inhibitor and nitrification inhibitor decreased N_2O emission considerably by slowing down urea hydrolyzation and inhibiting nitrification and denitrification. However, controversial reports were available on their effects on CH_4 production and emission. HQ and DCD are a pair that has currently attracted more attention in the research of this field. In this paper review is presented on general properties and mechanism of nitrification inhibitor and denitrification inhibitor, application of HQ/DCD in the paddy ecosystem and its effect and problems, and in particular, mechanism of HQ/DCD affecting CH_4 emission, with a view to providing some theoretical bases for reasonable application of HQ/DCD, effective reduction of emission of greenhouse gases and high use efficiency of nitrogen fertilizers in paddy field.

  19. Effects of environmental factors on soil CH4 and N2O lfuxes in three forest types in central subtropical China%中亚热带森林地表CH4和N2O通量影响因素分析

    Institute of Scientific and Technical Information of China (English)

    黄志宏; 张宇鸿; 沈燕; 张强; 王瑶; 凌威

    2016-01-01

    中亚热带森林是我国重要而独特的植被类型。本研究以本区域中3种典型的林分类型—杉木人工纯林、马尾松+石栎针阔混交林、青冈+石栎常绿阔叶林为研究对象,采用静态箱法—气相色谱法分析地表温室气体CH4、N2O浓度,同时观测样地环境因子。运用典型相关分析方法分析地表温室气体通量与环境因子的相关关系,并且对环境因子进行主成分分析。结果表明:(1)从总体来看,中亚热带森林地表温室气体通量是受多因素综合作用的结果,林地温室气体通量与林地环境因子间存在显著相关性(P<0.05),二者间的相关性程度也因不同林型而异;(2)在诸多环境因素中,温度是其中的主导因子,对地表温室气体影响相对较大,尤其是地表和地下5 cm处土壤温度;(3)其它非生物因素(如土壤水分、土壤碳氮含量、坡位等)对温室气体通量所起作用的大小则因具体的林型而异;(4)生物因素中不同林型间地表温室气体通量存在显著差异(P<0.05);(5)不同林型地表温室气体存在明显的季节动态。%Forest stands surface greenhouse gasfluxes play a pivotal role in the global carbon balance and global climate change. Forests in central subtropical is an important and special vegetation type in China. The typical forest types including Chinesefir plantation, Pinus massoniana + Lthocarpus glaber mixed forest, andCyclobalanopsis glauca + Lithocarpus glaber mixed evergreen broad-leaved forest were selected for the sampling plots using static chamber technique and gas chromatography analysis of soilsurface greenhouse gases (CH4 and N2O). The local environmental factors were recorded including soil surface temperature, soil temperature at 5 cm depth, air temperature, air temperature in the static chamber, soil moisture content in thefield. And soil total organic carbon and soil total organic nitrogen were measured

  20. Effects of different winter covering crops cultivation on methane(CH4)and nitrous oxide(N2O)emission fluxes from double-cropping paddy field%双季稻田种植不同冬季作物对甲烷和氧化亚氮排放的影响

    Institute of Scientific and Technical Information of China (English)

    唐海明; 肖小平; 帅细强; 汤文光; 林叶春; 汤海涛; 杨光立

    2012-01-01

    研究双季稻收获后填闲种植不同冬季作物在其生长季节内CH4和N2O的排放特征,对合理利用冬闲稻田,发展冬季作物生产及合理评价不同种植模式具有重要意义.采用静态箱-气相色谱法对冬季免耕直播黑麦草、紫云英、油菜以及翻耕移栽油菜和冬闲的双季稻田中甲烷(CH4)和氧化亚氮(N2O)排放进行了分析.结果表明:在冬季作物生长期,CH4、N2O平均排放通量和总排放量均表现为翻耕移栽油菜>免耕直播黑麦草>免耕直播油菜>免耕直播紫云英>冬闲.不同冬季作物稻田CH4和N2O总排放量与对照(冬闲)的差异均达到极显著水平(P<0.01);翻耕移栽油菜的双季稻田中CH4和N2O排放量最高,分别达2.989 g/m2和0.719 g/m2.翻耕移栽油菜稻田的CH4和N2O温室效应总和也最大,为2893.92 kg CO2/hm2;免耕直播黑麦草和免耕直播油菜处理次之,而免耕直播紫云英处理最低.种植不同冬季作物促进了稻田生态系统CH4和N2O的排放.

  1. Modeling greenhouse gas emissions (CO2, N2O, CH4) from managed arable soils with a fully coupled hydrology-biogeochemical modeling system simulating water and nutrient transport and associated carbon and nitrogen cycling at catchment scale

    Science.gov (United States)

    Klatt, Steffen; Haas, Edwin; Kraus, David; Kiese, Ralf; Butterbach-Bahl, Klaus; Kraft, Philipp; Plesca, Ina; Breuer, Lutz; Zhu, Bo; Zhou, Minghua; Zhang, Wei; Zheng, Xunhua; Wlotzka, Martin; Heuveline, Vincent

    2014-05-01

    , organic matter mineralisation, nitrification, denitrification, chemodenitrification and methanogenesis producing and consuming soil based greenhouse gases. The model application will present first validation results of the coupled model to simulate soil based greenhouse gas emissions as well as nitrate discharge from the Yanting catchment. The model application will also present the effects of different management practices (fertilization rates and timings, tilling, residues management) on the redistribution of N surplus within the catchment causing biomass productivity gradients and different levels of indirect N2O emissions along topographical gradients.

  2. N2O and CH4-emissions from energy crops - Can the use of organic fertilizers in form of biogas digestate be considered as a real alternative? Results from a three and a half year multi-site field study of energy crops fertilized with biogas digestate in so

    Science.gov (United States)

    Heintze, Gawan

    2016-04-01

    Gawan Heintze1,2, Matthias Drösler1, Ulrike Hagemann3and Jürgen Augustin3 1University of Applied Sciences Weihenstephan-Triesdorf, Chair of Vegetation Ecology, Weihenstephaner Berg 4, 85354 Freising, Germany 2Technische Universität München, Chair of Plant Nutrition, Emil-Ramann-Str. 2, 85354 Freising, Germany 3Leibniz Centre for Agricultural Landscape Research (ZALF), Eberswalder Straße 84, 15374 Müncheberg, Germany Together with industrial process-related emissions (8.1%) the actual GHG emissions from agriculture (7.5% - 70 million tones (Mt) of carbon dioxide (CO2)-equivalents) representing after energy-related emissions from combustion processes of fossil fuels (83.7%) the second largest budget of the Germany-wide total emissions per year. To reduce the EU's CO2 emissions by 20% by 2020 the cultivation of energy crops for biogas production, ideally coupled to a subsequent return of the resulting residues in form of biogas digestate is intended as one key element in the pathway of renewable energy production. Despite an increasing cultivation of energy crops for the production of biogas aiming to reduce the overall climate impact of the agricultural sector, it is still largely unknown how the application of ammonia-rich organic digestate effects field N2O emissions. Therefore, the collaborative research project "potential for reducing the release of climate-relevant trace gases in the cultivation of energy crops for the production of biogas" was launched. The main objective of the study was to determine an improved process understanding and to quantify the influence of mineral nitrogen fertilization, biogas digestate application, crop type and crop rotation, to gain precise and generalizable statements on the exchange of trace gases like nitrous oxide (N2O) and methane (CH4) on the resulting climate impact. Gas fluxes of N2O and CH4 were measured for three and a half years on two differently managed sites in maize monoculture with different applied organic

  3. “干清粪”系统猪粪快速堆肥过程中添加剂对甲烷、氧化亚氮和氨气排放的影响%Influence of bulking agents on CH4, N2O, and NH3 emissions during rapid composting of pig manure from the Chinese Ganqinfen system

    Institute of Scientific and Technical Information of China (English)

    Xiang-ping SUN; Peng LU; Tao JIANG; Frank SCHUCHARDT; Guo-xue LI

    2014-01-01

    研究目的:在“干清粪”系统猪粪堆肥过程中,不同添加剂(玉米秸秆、锯末和蘑菇渣)处理对甲烷、氧化亚氮和氨气排放的影响。  创新要点:将不同的添加剂(玉米秸秆、锯末和蘑菇渣)应用到快速堆肥系统中进行堆肥,测定了猪粪堆肥过程中甲烷、氧化亚氮和氨气的排放规律,为国内猪粪堆肥的应用提供理论指导。  重要结论:玉米秸秆作为添加剂能增加猪粪堆肥过程中氧化亚氮的排放;蘑菇渣添加剂增加了堆肥过程中甲烷的排放,然而减少了氧化亚氮及氨气的排放;锯末处理能增加堆肥过程中氨气的排放。添加剂能显著影响堆肥过程中氮素的损失。%Mismanagement of the composting process can result in emissions of CH4, N2O, and NH3, which have caused severe environmental problems. This study was aimed at determining whether CH4, N2O, and NH3 emissions from composting are affected by bulking agents during rapid composting of pig manure from the Chinese Ganqinfen system. Three bulking agents, corn stalks, spent mushroom compost, and sawdust, were used in composting with pig manure in 60 L reactors with forced aeration for more than a month. Gas emissions were measured continuously, and detailed gas emission patterns were obtained. Concentrations of NH3 and N2O from the composting pig manure mixed with corn stalks or sawdust were higher than those from the spent mushroom compost treatment, especial y the sawdust treatment, which had the highest total nitrogen loss among the three runs. Most of the nitrogen was lost in the form of NH3, which accounts for 11.16% to 35.69% of the initial nitrogen. One-way analysis of variance for NH3 emission showed no significant differences between the corn stalk and sawdust treatments, but a significant difference was noted between the spent mushroom compost and sawdust treatments. The introduction of sawdust reduced CH4 emission more than

  4. 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.

  5. 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.

    ), Universidad de Concepci´on, Casilla 160-C, Concepci´on, Chile 5Department of Oceanography, University of Cape Town, Rondebosch, South Africa 6School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook NY 11794, USA 7State Key Laboratory... America – Chile and Peru) are more volu- minous than those in the Atlantic (off Southwest Africa – Namibia, and off Northwest Africa – Mauritania) because of the generally lower subsurface O2 concentrations throughout the Pacific. In all but one (off...

  6. Emission of CH4 and N2O from Wastewater Treatment Plants (6B)

    DEFF Research Database (Denmark)

    Thomsen, M.; Lyck, E.

    The report gives a detailed description of the national methodology, national statistics and data background used for the first time implementation of Waste Category 6B in the National Inventory Report. Emissions of methane and nitrous oxide from wastewater handling have been estimated from the r...

  7. CH_{4} production in the deep soil as a source of stem CH_{4} emission in Fagus sylvatica}

    Science.gov (United States)

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

    2017-04-01

    Predicting greenhouse gas (GHG) fluxes on a global scale requires understanding fluxes on the local scale. Understanding GHG processes in soil-plant-atmosphere systems is essential to understand and mitigate GHG fluxes on the local scale. Forests are known to act as carbon sink. Yet, trees at waterlogged sites are known to emit large amounts of CH4, what can offset the positive GHG balance due the CO2 that is sequestered as wood. Generally, upland trees like European beech (Fagus sylvatica L.) are assumed not to emit CH4, and the upland forest soils are regarded as CH4 sinks. Soil-atmosphere fluxes and stem-atmosphere fluxes of CH4 were studied together with soil gas profiles at two upland beech forest sites in Germany and Czech Republic. Soil was a net CH4 sink at both sites. While most trees showed no or low emissions, one beech tree had exorbitant CH4 emissions that were higher than the CH4 sink capacity of the soil. A soil survey showed strong redoximorphic color patterns in the soil adjacent to this tree. Although the soil around the tree was taking up CH4, the soil gas profiles around this tree showed CH4 production at a soil depth >0.3 m. We interpret the coincidence of the production of CH4 in the deep soil below the beech with the large stem emissions as strong hint that there is a transport link between the soil and stem. We think that the root system represents a preferential transport system for CH4 despite the fact that beech roots usually do not have a special gas transport tissue. The observed CH4 stem emissions represent an important CH4 flux in this ecosystem, and, thus, should be considered in future research. Acknowledgement This research was supported by the Czech Academy of Sciences and the German Academic Exchange Service within the project "Methane (CH4) and nitrous oxide (N2O) emissions from Fagus sylvatica trees" (DAAD-15-03), the Czech Science Foundation (17-18112Y), National Programme for Sustainability I (LO1415) and project DFG (MA 5826

  8. Short-term nitrogen additions can shift a coastal wetland from a sink to a source of N 2O

    Science.gov (United States)

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

    2011-08-01

    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 (N 2O, CH 4, and CO 2) 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 N 2O, CH 4 and respiratory CO 2 fluxes from nitrate-enriched plots in a Spartina patens marsh (receiving single additions of NaNO 3 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 N 2O and CH 4 fluxes in both opaque and transparent chambers to test the influence of light on gas flux measurements. Background fluxes of N 2O in July 2009 averaged -33 μmol N 2O m -2 day -1. However, within 1 h of nutrient additions, N 2O fluxes were significantly greater in plots receiving nitrate additions relative to controls in July 2009. Respiratory rates and CH 4 fluxes were not significantly affected. N 2O fluxes were significantly higher in dark than in transparent chambers, averaging 108 and 42 μmol N 2O 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, N 2O and CH 4 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 N 2O 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 N 2O and CH 4 fluxes observed, exceeded half

  9. N2O emission of HD vehicles

    NARCIS (Netherlands)

    Riemersma, I.J.; Jordaan, K.; Oonk, J.

    2003-01-01

    N2O is known to be a greenhouse gas with a high global warming potential, approximately 296 times higher than that of CO2 [11]. In road vehicles N2O is mostly formed by reactions in the exhaust catalyst. The IPCC (Intergovernmental Panel on Climate Changes) uses emission factors from research perfor

  10. N2O fluxes from the littoral zone of a Chinese reservoir

    Science.gov (United States)

    Yang, M.; Geng, X. M.; Grace, J.; Jia, Y. F.; Liu, Y. Z.; Jiao, S. W.; Shi, L. L.; Lu, C.; Zhou, Y.; Lei, G. C.

    2015-08-01

    There have been few studies of greenhouse gas emissions from reservoirs, despite the remarkable growth in the number of reservoirs in developing countries. We report a case study that focuses on the littoral zone of a major Chinese reservoir, where we established measurements of N2O fluxes using the static chamber technique at five different water levels (deep water, shallow water, seasonally flooded, control for seasonally flooded, and non-flooded). The "control for seasonal flooded" had similar vegetation to the "seasonally flooded" but was not actually flooded as it was on a higher piece of land. Seasonal, diurnal and spatial variations of N2O flux and environmental factors were monitored throughout the growing season which included a flood event during summer rains. The N2O flux ranged from -136.6 to 381.8 μg m-2 h-1 averaging 6.8 μg m-2 h-1. Seasonal and spatial variation was significant but diurnal variation was not. Non-flooded dry land emitted more N2O than flooded land, no matter whether it was permanently or seasonally flooded. Piecewise correlation was found between N2O flux, air temperature and soil nitrate concentration. Positive correlation was shown between N2O flux and dissolved oxygen in water. There were significantly higher emissions from farmland. We compared these results with our recently published study of CH4 emissions, carried out simultaneously at the same site as those in the present study. Completely different patterns between the two gases are demonstrated. We conclude that the littoral zone is a hotspot for N2O emissions in the summer, especially when the shores of the lake are used for the farming of maize. But in terms of the overall greenhouse gas budget, the fluxes of N2O are not as important as those of CH4.

  11. Subsoil methanogenesis as source of stem CH4 emission in upland forest trees: preferential CH4 transport via the root system?

    Science.gov (United States)

    Maier, M.; Machacova, K.; Urban, O.; Friederike, L.

    2016-12-01

    Quantifying and understanding green house gas fluxes in natural soil-plant-atmosphere systems are crucial to predicting global climate change. Wetland species or trees at waterlogged sites are known to emit large amounts of CH4. Yet upland forest soils are regarded as CH4 sinks and tree species like upland European beech (Fagus sylvatica, L.) are assumed not to emit CH4. We studied the soil-atmosphere and stem-atmosphere fluxes of CH4, and soil gas profiles at two upland beech forest sites in Central Europe. Soil was a net CH4 sink at both. Unusually there was one beech tree with substantial CH4 emissions that were higher than the CH4 sink of the soil. The soil gas profile at this tree indicated CH4 production at a soil depth >0.3 m, despite the net uptake of CH4 observed at the soil surface adjacent to the tree. Field soil assessment showed strong redoximorphic color patterns in the adjacent soil. We think that there is a transport link between the soil and stem via the root system representing a preferential transport mechanism for CH4 despite the fact that beech roots usually do not bear aerenchyma. The gas transport process , either via dissolved CH4 in the xylem water or in the root gas phase, is not yet clear. The observed CH4 stem emissions represent an important CH4flux in this ecosystem, und thus should be considered in future research. AcknowledgementThis research was financially supported by the Czech Academy of Sciences and the German Academic Exchange Service within the project "Methane (CH4) and nitrous oxide (N2O) emissions from Fagus sylvatica trees" (DAAD-15-03), National Programme for Sustainability I (LO1415) and project DFG (MA 5826/2-1). We would like to thank Marek Jakubik, Katerina Svobodova, Sinikka Paulus, Ellen Halaburt and Sally Haddad for technical support.

  12. Use of the nitrification inhibitor dicyandiamide (DCD) does not mitigate N2O emission from bovine urine patches under Oxisol in Northwest Brasil

    NARCIS (Netherlands)

    Mazzetto, A.M.; Barneze, A.S.; Feigl, B.J.; Groenigen, van J.W.; Oenema, O.; Klein, de C.A.M.; Cerri, C.C.

    2015-01-01

    Animal production systems are important sources of greenhouse gases (GHGs), especially methane (CH4) and nitrous oxide (N2O). GHG emissions from urine patches have been extensively studied in temperate climates, with few studies under tropical conditions. Here we examined the driving factors of N2O

  13. N2O molecular tagging velocimetry

    Science.gov (United States)

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

    2012-03-01

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

  14. 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.

  15. CH4 Separation from Coal Bed Methane by Hydrate in the SDS and THF Solution

    Directory of Open Access Journals (Sweden)

    Jianzhong Zhao

    2016-01-01

    Full Text Available Hydrate-based separation experiments on simulate coal bed methane gas have been conducted in THF solution and SDS solution. In this work, a novel hydrate-based gas separation process was used to enhance CH4 separation from a 65.7% CH4/20.2% N2/O2 gas mixture in the presence of 300 ppm SDS and 19% THF solution. The characteristics of the CH4 separation efficiency, fluctuation of temperature, and pressure were studied at different promoter solution. It was found that hydrate formation was induced by promoter in the solution and occurred immediately as the experiments were started. THF performed better than SDS for CH4 separation from the CH4/N2/O2 gas mixture. In particular, the separation coefficients of CH4 and N2 were compared in two solutions. The gas mixture S.Fr. or CH4 recovery is increased from 1.056 to 1.259 while SF of N2 is decreased from 1.183 to 0.634 in THF solution.

  16. 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

    al. (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, USA. Flessa, H., R. Ruser, R. Schilling, N. Loftfield, J.C. Munch, E.A. Kaiser and F. Beese, 2002. N2O and CH4 fluxes in potato fields: automated measurement, management effects and temporal variation. Geoderma 105(3-4): 307-325. Hénault, C., A. Grossel, B. Mary, M. Roussel and J. Léonard, 2012. Nitrous Oxide Emission by Agricultural Soils: A Review of Spatial and Temporal Variability for Mitigation. Pedosphere 22(4): 426-433. Senapati, N., A. Chabbi, A. Faé Giostri, J. B. Yeluripati and P. Smith, 2016. Modelling nitrous oxide emissions frommown-grass and grain-cropping systems: Testing and sensitivity analysis of DailyDayCent using high frequency measurements. Science of the Total Environment 572: 955-977.

  17. Historical Pattern and Future Trajectories of Terrestrial N2O Emission driven by Multi-factor Global Changes

    Science.gov (United States)

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

    2015-12-01

    Nitrous oxide (N2O) is among the most important greenhouse gases only next to carbon dioxide (CO2) and methane (CH4) due to its long life time and high radiative forcing (with a global warming potential 265 times as much as CO2 at 100-year time horizon). The Atmospheric concentration of N2O has increased by 20% since pre-industrial era, and this increase plays a significant role in shaping anthropogenic climate change. However, compared to CO2- and CH4-related research, fewer studies have been performed in assessing and predicting the spatiotemporal patterns of N2O emission from natural and agricultural soils. Here we used a coupled biogeochemical model, DLEM, to quantify the historical and future changes in global terrestrial N2O emissions resulting from natural and anthropogenic perturbations including climate variability, atmospheric CO2 concentration, nitrogen deposition, land use and land cover changes, and agricultural land management practices (i.e., synthetic nitrogen fertilizer use, manure application, and irrigation etc.) over the period 1900-2099. We focused on inter-annual variation and long-term trend of terrestrial N2O emission driven by individual and combined environmental changes during historical and future periods. The sensitivity of N2O emission to climate, atmospheric composition, and human activities has been examined at biome-, latitudinal, continental and global scales. Future projections were conducted to identify the hot spots and hot time periods of global N2O emission under two emission scenarios (RCP2.6 and RCP8.5). It provides a modeling perspective for understanding human-induced N2O emission growth and developing potential management strategies to mitigate further atmospheric N2O increase and climate warming.

  18. The European land and inland water CO2, CO, CH4 and N2O balance between 2001 and 2005

    Energy Technology Data Exchange (ETDEWEB)

    Luyassaert, S [CEA-CNRS-UVSQ, LSCE; Abril, G [Laboratoire EPOC, CNRS; Andres, Robert Joseph [ORNL; Bastviken, D [Linkoping University; Bellassen, V [CEA-CNRS-UVSQ, LSCE; Bergamaschi, P [European Commission Joint Research Centre; Bousquet, P [CEA-CNRS-UVSQ, LSCE; Chevallier, F [CEA-CNRS-UVSQ, LSCE; Ciais, P. [LSCE/CEA, Gif-sur-Yvette, France; Corazza, M [European Commission Joint Research Centre; Dechow, R [Johann Heinrich von Thünen Institute; Erb, K-H [Alpen-Adria Universitaet Klagenfurt-Vienna-Graz; Etiope, G [Istituto Nazionale di Geofisica e Vulcanologia; Fortems-Cheiney, A [CEA-CNRS-UVSQ, LSCE; Grassi, G [European Commission Joint Research Centre; Hartmann, J [University of Hamburg; Jung, M. [Max Planck Institute for Biogeochemistry; Lathiere, J [CEA-CNRS-UVSQ, LSCE; Lohila, A [Finnish Meteorological institute; Mayorga, E [University of Washington; Moosdorf, N [University of Hamburg; Njakou, D [University of Antwerp; Otto, J [CEA-CNRS-UVSQ, LSCE; Papale, D. [University of Tuscia; Peters, W [Wageningen University and Research Centre, The Netherlands; Peylin, P [CEA-CNRS-UVSQ, LSCE; Raymond, Peter A [Yale School of Forestry and Environmental Studies; Rodenbeck, C [Max Planck Institute for Biogeochemistry; Saarnio, S [University of Eastern Finland; Schulze, E.-D. [Max Planck Institute for Biogeochemistry; Szopa, S [CEA-CNRS-UVSQ, LSCE; Thompson, R [CEA-CNRS-UVSQ, LSCE; Verkerk, P [European Forest Institute; Vuichard, N [CEA-CNRS-UVSQ, LSCE; Wang, R [Peking University; Wattenbach, M [Helmholtz Centre Potsdam GFZ German Research Centre For Geosciences; Zaehle, S [Max Planck Institute for Biogeochemistry

    2012-01-01

    Globally, terrestrial ecosystems have absorbed about 30% of anthropogenic greenhouse gas emissions over the period 2000-2007 and inter-hemispheric gradients indicate that a significant fraction of terrestrial carbon sequestration must be north of the Equator. We present a compilation of the CO{sub 2}, CO, CH{sub 4} and N{sub 2}O balances of Europe following a dual constraint approach in which (1) a land-based balance derived mainly from ecosystem carbon inventories and (2) a land-based balance derived from flux measurements are compared to (3) the atmospheric data-based balance derived from inversions constrained by measurements of atmospheric GHG (greenhouse gas) concentrations. Good agreement between the GHG balances based on fluxes (1294 {+-} 545 Tg C in CO{sub 2}-eq yr{sup -1}), inventories (1299 {+-} 200 Tg C in CO{sub 2}-eq yr{sup -1}) and inversions (1210 {+-} 405 Tg C in CO{sub 2}-eq yr{sup -1}) increases our confidence that the processes underlying the European GHG budget are well understood and reasonably sampled. However, the uncertainty remains large and largely lacks formal estimates. Given that European net land to atmosphere exchanges are determined by a few dominant fluxes, the uncertainty of these key components needs to be formally estimated before efforts could be made to reduce the overall uncertainty. The net land-to-atmosphere flux is a net source for CO{sub 2}, CO, CH{sub 4} and N{sub 2}O, because the anthropogenic emissions by far exceed the biogenic sink strength. The dual-constraint approach confirmed that the European biogenic sink removes as much as 205 {+-} 72 Tg C yr{sup -1} from fossil fuel burning from the atmosphere. However, This C is being sequestered in both terrestrial and inland aquatic ecosystems. If the C-cost for ecosystem management is taken into account, the net uptake of ecosystems is estimated to decrease by 45% but still indicates substantial C-sequestration. However, when the balance is extended from CO{sub 2} towards the main GHGs, C-uptake by terrestrial and aquatic ecosystems is offset by emissions of non-CO{sub 2} GHGs. As such, the European ecosystems are unlikely to contribute to mitigating the effects of climate change.

  19. Limits of agricultural greenhouse gas calculators to predict soil N2O and CH4 fluxes in tropical agriculture

    DEFF Research Database (Denmark)

    Richards, Meryl; Metzel, Ruth; Chirinda, Ngonidzashe;

    2016-01-01

    input data. GHG calculators, however, rely on models calibrated from measurements conducted overwhelmingly under temperate, developed country conditions. Here we show that GHG calculators may poorly estimate emissions in tropical developing countries by comparing calculator predictions against...... measurements from Africa, Asia, and Latin America. Estimates based on GHG calculators were greater than measurements in 70% of the cases, exceeding twice the measured flux nearly half the time. For 41% of the comparisons, calculators incorrectly predicted whether emissions would increase or decrease...... with a change in management. These results raise concerns about applying GHG calculators to tropical farming systems and emphasize the need to broaden the scope of the underlying data....

  20. Subtask 1.22 - Microbial Cycling of CH4, CO2, and N2O in a Wetlands Environment

    Energy Technology Data Exchange (ETDEWEB)

    Dingyi Ye; Bethany Kurz; Marc Kurz

    2008-12-31

    Soil microbial metabolic activities play an important role in determining CO{sub 2}, CH{sub 4}, and N{sub 2}O fluxes from terrestrial ecosystems. To verify and evaluate CO{sub 2} sequestration potential by wetland restoration in the Prairie Pothole Region (PPR), as well as to address concern over restoration effects on CH{sub 4} and N{sub 2}O emissions, laboratory and in situ microcosm studies on microbial cycling of CO{sub 2}, CH{sub 4}, and N{sub 2}O were initiated. In addition, to evaluate the feasibility of the use of remote sensing to detect soil gas flux from wetlands, a remote-sensing investigation was also conducted. Results of the laboratory microcosm study unequivocally proved that restoration of PPR wetlands does sequester atmospheric CO{sub 2}. Under the experimental conditions, the simulated restored wetlands did not promote neither N{sub 2}O nor CH{sub 4} fluxes. Application of ammonia enhanced both N{sub 2}O and CH{sub 4} emission, indicating that restoration of PPR wetlands may reduce both N{sub 2}O and CH{sub 4} emission by cutting N-fertilizer input. Enhancement of CO{sub 2} emission by the N-fertilizer was observed, and this observation revealed an overlooked fact that application of N-fertilizer may potentially increase CO{sub 2} emission. In addition, the CO{sub 2} results also demonstrate that wetland restoration sequesters atmospheric carbon not only by turning soil conditions from aerobic to anoxic, but also by cutting N-fertilizer input that may enhance CO{sub 2} flux. The investigation on microbial community structure and population dynamics showed that under the experimental conditions restoration of the PPR wetlands would not dramatically increase population sizes of those microorganisms that produce N{sub 2}O and CH{sub 4}. Results of the in situ study proved that restoration of the PPR wetland significantly reduced CO{sub 2} flux. Ammonia enhanced the greenhouse gas emission and linearly correlated to the CO{sub 2} flux within the experimental rate range (46-200 kg N ha{sup -1}). The results also clarified that the overall reduction in global warming potential (GWP) by the PPR wetland restoration was mainly contributed from reduction in CO{sub 2} flux. These results demonstrate that restoration of currently farmed PPR wetlands will significantly reduce the overall GWP budget. Remote sensing investigations indicate that while the 15-meter resolution of the imagery was sufficient to delineate multiple zones in larger wetlands, it was not sufficient for correlation with the ground-based gas flux measurement data, which were collected primarily for smaller wetland sites (<250 meters) in the areas evaluated by this task. To better evaluate the feasibility of using satellite imagery to quantify wetland gas flux, either higher-resolution satellite imagery or gas flux data from larger wetland sites is needed.

  1. Limits of agricultural greenhouse gas calculators to predict soil N2O and CH4 fluxes in tropical agriculture.

    Science.gov (United States)

    Richards, Meryl; Metzel, Ruth; Chirinda, Ngonidzashe; Ly, Proyuth; Nyamadzawo, George; Duong Vu, Quynh; de Neergaard, Andreas; Oelofse, Myles; Wollenberg, Eva; Keller, Emma; Malin, Daniella; Olesen, Jørgen E; Hillier, Jonathan; Rosenstock, Todd S

    2016-05-20

    Demand for tools to rapidly assess greenhouse gas impacts from policy and technological change in the agricultural sector has catalyzed the development of 'GHG calculators'- simple accounting approaches that use a mix of emission factors and empirical models to calculate GHG emissions with minimal input data. GHG calculators, however, rely on models calibrated from measurements conducted overwhelmingly under temperate, developed country conditions. Here we show that GHG calculators may poorly estimate emissions in tropical developing countries by comparing calculator predictions against measurements from Africa, Asia, and Latin America. Estimates based on GHG calculators were greater than measurements in 70% of the cases, exceeding twice the measured flux nearly half the time. For 41% of the comparisons, calculators incorrectly predicted whether emissions would increase or decrease with a change in management. These results raise concerns about applying GHG calculators to tropical farming systems and emphasize the need to broaden the scope of the underlying data.

  2. The European land and inland water CO2, CO, CH4 and N2O balance between 2001 and 2005

    NARCIS (Netherlands)

    Luyssaert, S.; Abril, G.; Andres, R.; Bastviken, D.; Bellassen, V.; Bergamaschi, P.; Bousquet, P.; Chevallier, F.; Ciais, P.; Corazza, M.; Dechow, R.; Erb, K.-H.; Etiope, G.; Fortems-Cheiney, A.; Grassi, G.; Hartmann, J.; Jung, M.; Lathière, J.; Lohila, A.; Mayorga, E.; Moosdorf, N.; Njakou, D. S.; Otto, J.; Papale, D.; Peters, W.; Peylin, P.; Raymond, P.; Rödenbeck, C.; Saarnio, S.; Schulze, E.-D.; Szopa, S.; Thompson, R.; Verkerk, P. J.; Vuichard, N.; Wang, R.; Wattenbach, M.; Zaehle, S.

    2012-01-01

    Globally, terrestrial ecosystems have absorbed about 30% of anthropogenic greenhouse gas emissions over the period 2000-2007 and inter-hemispheric gradients indicate that a significant fraction of terrestrial carbon sequestration must be north of the Equator. We present a compilation of the CO2, CO,

  3. Limits of agricultural greenhouse gas calculators to predict soil N2O and CH4 fluxes in tropical agriculture

    Science.gov (United States)

    Richards, Meryl; Metzel, Ruth; Chirinda, Ngonidzashe; Ly, Proyuth; Nyamadzawo, George; Duong Vu, Quynh; de Neergaard, Andreas; Oelofse, Myles; Wollenberg, Eva; Keller, Emma; Malin, Daniella; Olesen, Jørgen E.; Hillier, Jonathan; Rosenstock, Todd S.

    2016-05-01

    Demand for tools to rapidly assess greenhouse gas impacts from policy and technological change in the agricultural sector has catalyzed the development of ‘GHG calculators’— simple accounting approaches that use a mix of emission factors and empirical models to calculate GHG emissions with minimal input data. GHG calculators, however, rely on models calibrated from measurements conducted overwhelmingly under temperate, developed country conditions. Here we show that GHG calculators may poorly estimate emissions in tropical developing countries by comparing calculator predictions against measurements from Africa, Asia, and Latin America. Estimates based on GHG calculators were greater than measurements in 70% of the cases, exceeding twice the measured flux nearly half the time. For 41% of the comparisons, calculators incorrectly predicted whether emissions would increase or decrease with a change in management. These results raise concerns about applying GHG calculators to tropical farming systems and emphasize the need to broaden the scope of the underlying data.

  4. Microcosm N2O emissions wth calibration

    Science.gov (United States)

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

  5. Natural and Anthropogenic Controls over Global Terrestrial N2O Emission Growth at a Century-Long Time Scale

    Science.gov (United States)

    Lu, C.; Tian, H.; Kamaljit, K.; Zhang, B.

    2014-12-01

    The Atmospheric concentration of nitrous oxide (N2O) has increased by 20% relative to pre-industrial level. It has attracted growing attention since N2O has long life time and radiative forcing 265 times higher than CO2 at 100-year time horizon. Global N2O emission from terrestrial ecosystem is among the most important contributors to the increase of atmospheric N2O. However, compared to CO2- and CH4-related research, less intensive studies have been performed in assessing the spatiotemporal patterns of terrestrial N2O emission and attributing its changes to both natural and anthropogenic disturbances across the globe. Here we integrated gridded time-series data of climate variability, atmospheric CO2 concentration, nitrogen deposition, land use and land cover changes, and agricultural land management practices (i.e., synthetic nitrogen fertilizer use, manure application, and irrigation etc.) to a process-based land ecosystem model, DLEM, for answering the above questions. During 1900-2010, the inter-annual variation and long-term trend of terrestrial N2O emission driven by individual and combined environmental changes have been examined. Through this, we distinguished and quantified the relative contributions of changes in climate, atmospheric composition, and human activities to N2O emission growth at biome-, latitudinal, continental and global scales. The impacts of climate variability, and increasing nitrogen input, particularly nitrogen fertilizer use along with enhanced food production, have been paid special attention. Hot spots and hot time periods of global N2O emission are identified in this study. It provides clue for scientific community and policy makers to develop potential management strategies for mitigating atmospheric N2O increase and climate warming.

  6. N2O concentrations in boreal lakes are linked to nitrate and temperature

    Science.gov (United States)

    Kortelainen, Pirkko; Rantakari, Miitta; Alm, Jukka; Larmola, Tuula; Juutinen, Sari; Bergström, Irina; Huttunen, Jari T.; Silvola, Jouko; Martikainen, Pertti J.

    2013-04-01

    While regional and global estimates for carbon dioxide (CO2) and methane (CH4) emission from lakes are presently available, nitrous oxide (N2O) evasion from lakes and streams and the primary drivers regulating the fluxes have remained poorly studied. Freshwater N2O data are scarce and mostly based on short term measurements from a few lakes/rivers. The largest N2O data was collected by Whitfield et al. (2011) focusing on 121 small, polymictic headwater lakes in Ireland in spring 2008. We gathered the so-far largest seasonal/annual N2O data from boreal lakes. A subpopulation of 112 lakes from the boreal zone in Finland (from 60oN to 69oN) was randomly selected from the Nordic Lake Survey (NLS) data base. Water chemistry, catchment land use, climatic drivers and variables linked to catchment topography (e.g. max depth of the lake) were determined for each lake. The lakes were sampled four times per year (before and after ice melt, at the end of a summer stratification and during a fall overturn) from four depths (1 m from the surface, middle of the lake, 1 m from the sediment and 20 cm from the sediment) at the deepest point of the lake for N2O concentrations and physical and chemical characteristics. Finnish lakes are predominantly dimictic and the average length of the ice cover period ranges from about 5 months in the south to over 7 months in the north. The variability in N2O concentrations in the lake population was large in each season and depth. Although highest N2O concentrations were often found in bottom water samples, N2O and oxygen were poorly linked to each other (weak correlation only in winter samples). This is in contrast to CO2 concentrations in the study lakes, which were strongly linked to oxygen concentrations (r2= 0.79, n = 2740, p Science of the Total Environment 410-411: 217-225. Please fill in your abstract text.

  7. Effects of Eriophorum vaginatum on N_{2}O emissions at a restored peatland

    Science.gov (United States)

    Brummell, Martin; Lazcano, Cristina; Strack, Maria

    2016-04-01

    Restoration of peatlands extracted for horticultural peat production includes both deliberate and accidental introduction of a wide range of plant species, including vascular plants and bryophytes. The roots of vascular plants provide a channel for the movement of greenhouse gases (GHG) including N2O in many soil ecosystems, and may stimulate production of N2O or have other effects via the release of root exudates that are then taken up by soil microorganisms such as heterotrophic denitrifiers. Here we carried out a field study in order to evaluate the effects of Eriophorum vaginatum, an abundant sedge at the harvested peatland at Seba Beach, Alberta, Canada, (53° 27'17.2"N 114° 52'52.0"W) where restoration efforts began in late 2012, and is the dominant ground cover in some areas. We hypothesized that E. vaginatum would increase net N2O production from peat compared to areas of bare peat or moss. We measured net GHG exchange for CO2, CH4, and N2O over one growing season (May-September 2015) using static chambers within this peatland to compare between plots containing E. vaginatum and plots lacking vascular plants. Plots were located along a transect of increasing water table, in order to discriminate between the effects of E. vaginatum and the prevailing hydrological conditions on N2O fluxes. Net fluxes of N2O from the peat to the atmosphere were observed throughout the experimental area, as well as fluxes in the opposite direction, in which the peat removed N2O from the atmosphere inside the chamber. Non-zero fluxes were highly variable in both occurrence and magnitude, though a small number of plots accounted for the majority of measured fluxes. Neither aboveground biomass of E. vaginatum nor its presence in a plot was correlated with either frequency or direction of N2O flux measurements. Other factors, such as water table fluctuations and temperature may be stronger drivers of these microbially-mediated processes than vegetation at this stage of the

  8. 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.

  9. Nonpolar nitrous oxide dimer: fundamentals of the mixed 14N2O-15N2O dimer and new combination bands of (14N2O)2 and (15N2O)2 involving the Bu, intermolecular bend.

    Science.gov (United States)

    Dehghany, M; Afshari, Mahin; Abusara, Z; Moazzen-Ahmadi, N

    2009-09-21

    Spectra of the nonpolar nitrous oxide dimer in the region of the N2O v1 fundamental band are observed in a pulsed supersonic slit jet expansion probed with a tunable diode laser. Four bands are analysed: two fundamentals of the mixed 14N2O-15N2O dimer and combination bands involving the intermolecular disrotation of the monomers (Bu intermolecular bend) for both (14N2O)2 and (15N2O)2. Because the determination of this intermolecular frequency relies on the experimentally unknown frequency of the (forbidden) symmetric fundamental, we used previously published ab initio results and their proximity to our experimental values to assign the upper state of the combination bands. The resulting intermolecular disrotation frequencies are 42.3(1.0) and 41.6(1.0) cm(-1) for the (14N2O)2 and (15N2O)2, respectively. This represents the first observation of the mixed 14N2O-15N2O dimer, and the direct determination of a second intermolecular frequency for the nonpolar (N2O)2.

  10. 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.

  11. 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.

  12. 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

  13. Characteristics of premixed, laminar CO/N2O flames

    NARCIS (Netherlands)

    Kalff, P.J.; Alkemade, C.T.J.

    1972-01-01

    Several properties are studied of fuel-rich (CO:N2O = 1.5:1) and stoichiometrie (CO:N2O = 1:1) carbon monoxide/nitrous oxide flames with varying water content up to 10%. Flame temperatures, ranging from 2680 to 2860°K. are measured with the line-reversal method, and compared with calculated adiabati

  14. Hydrologic and Biogeochemical Controls on Hyporheic N2O Emissions

    Science.gov (United States)

    Quick, A. M.; Reeder, W. J.; Farrell, T. B.; Tonina, D.; Feris, K. P.; Benner, S. G.

    2016-12-01

    The hyporheic zones (HZ) of streams and rivers may be a significant source of nitrous oxide (N2O) emissions, but the hydrological and biogeochemical controls on if and how much N2O is released from the HZ are not well constrained. We employed a multidisciplinary approach to examine HZ N2O emissions that included a column experiment and two large-scale flume experiments in which we controlled initial particulate organic matter, exogenous nitrate loading, flow rates, and streambed geomorphology at the scales of a natural stream. In both 1D (column) and 2D (flume) experiments, hyporheic flow paths and residence times were modeled and measured with tracers. We measured in-situ pore water concentrations of dissolved oxygen and inorganic nitrogen species, including dissolved N2O. We observed both N2O production and consumption along HZ flow paths. Our results indicate that N2O generation and consumption are dictated by hyporheic residence times and biological nitrogen reduction rates. For N2O to be released from the HZ, residence times must be sufficiently long (or reaction rates must be sufficiently fast) to promote reduction of nitrate to N2O. However, if residence times are too long (or reaction rates are too fast) N2O will be converted to N2. As a result, only a small fraction of HZ flow paths will produce N2O at a given time. For example, although we observed concentrations up to 122 μg L-1 N-N2O in the HZ, most of this N2O was reduced to N2 before leaving the HZ and entering the surface stream water. We also observed that higher N2O concentrations in the HZ correspond to high surface water nitrate and low carbon reactivity in the sediments. The conceptual model supported by these flume and column experiments suggests that both reduction of nitrate loading and increased hyporheic residence times may moderate the potential for N2O emissions from stream hyporheic zones.

  15. N2O emissions from full-scale nitrifying biofilters.

    Science.gov (United States)

    Bollon, Julien; Filali, Ahlem; Fayolle, Yannick; Guerin, Sabrina; Rocher, Vincent; Gillot, Sylvie

    2016-10-01

    A full-scale nitrifying biofilter was continuously monitored during two measurement periods (September 2014; February 2015) during which both gaseous and liquid N2O fluxes were monitored on-line. The results showed diurnal and seasonal variations of N2O emissions. A statistical model was run to determine the main operational parameters governing N2O emissions. Modification of the distribution between the gas phase and the liquid phase was observed related to the effects of temperature and aeration flow on the volumetric mass transfer coefficient (kLa). With similar nitrification performance values, the N2O emission factor was twice as high during the winter campaign. The increase in N2O emissions in winter was correlated to higher effluent nitrite concentrations and suspected increased biofilm thickness.

  16. A combustion setup to precisely reference δ13C and δ2H isotope ratios of pure CH4 to produce isotope reference gases of δ13C-CH4 in synthetic air

    Directory of Open Access Journals (Sweden)

    H. Schaefer

    2012-09-01

    Full Text Available Isotope records of atmospheric CH4 can be used to infer changes in the biogeochemistry of CH4. One factor currently limiting the quantitative interpretation of such changes are uncertainties in the isotope measurements stemming from the lack of a unique isotope reference gas, certified for δ13C-CH4 or δ2H-CH4. We present a method to produce isotope reference gases for CH4 in synthetic air that are precisely anchored to the VPDB and VSMOW scales and have δ13C-CH4 values typical for the modern and glacial atmosphere. We quantitatively combusted two pure CH4 gases from fossil and biogenic sources and determined the δ13C and δ2H values of the produced CO2 and H2O relative to the VPDB and VSMOW scales within a very small analytical uncertainty of 0.04‰ and 0.7‰, respectively. We found isotope ratios of −39.56‰ and −56.37‰ for δ13C and −170.1‰ and −317.4‰ for δ2H in the fossil and biogenic CH4, respectively. We used both CH4 types as parental gases from which we mixed two filial CH4 gases. Their δ13C was determined to be −42.21‰ and −47.25‰ representing glacial and present atmospheric δ13C-CH4. The δ2H isotope ratios of the filial CH4 gases were found to be −193.1‰ and −237.1‰, respectively. Next, we mixed aliquots of the filial CH4 gases with ultrapure N2/O2 (CH4 ≤ 2 ppb producing two isotope reference gases of synthetic air with CH4 mixing ratios near atmospheric values. We show that our method is reproducible and does not introduce isotopic fractionation for δ13C within the uncertainties of our detection limit (we cannot conclude this for δ2H because our system is currently not prepared for δ2H-CH4 measurements in air samples. The general principle of our method can be applied to produce synthetic isotope reference gases targeting δ2H-CH4 or other gas species.

  17. (CH4)-C-14 Measurements in Greenland Ice: Investigating Last Glacial Termination CH4 Sources

    DEFF Research Database (Denmark)

    Petrenko, V. V.; Smith, A. M.; Brook, E. J.;

    2009-01-01

    The cause of a large increase of atmospheric methane concentration during the Younger Dryas-Preboreal abrupt climatic transition (similar to 11,600 years ago) has been the subject of much debate. The carbon-14 (C-14) content of methane ((CH4)-C-14) should distinguish between wetland and clathrate...... contributions to this increase. We present measurements of (CH4)-C-14 in glacial ice, targeting this transition, performed by using ice samples obtained from an ablation site in west Greenland. Measured (CH4)-C-14 values were higher than predicted under any scenario. Sample (CH4)-C-14 appears to be elevated...... by direct cosmogenic C-14 production in ice. C-14 of CO was measured to better understand this process and correct the sample (CH4)-C-14. Corrected results suggest that wetland sources were likely responsible for the majority of the Younger Dryas-Preboreal CH4 rise....

  18. N2O - direct versus indirect effects on emissions

    Science.gov (United States)

    Zechmeister-Boltenstern, Sophie; Kitzler, Barbara

    2013-04-01

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

  19. Nitrogen fertiliser formulation: The impact on N2O emissions

    Science.gov (United States)

    Harty, Mary; Krol, Dominika; Carolan, Rachael; McNeill, Gavin; McGeough, Karen; Laughlin, Ronnie; Watson, Catherine; Richards, Karl; Lanigan, Gary; Forrestal, Patrick

    2015-04-01

    Agriculture was responsible for 31% of Ireland's Agricultural Greenhouse Gas (GHG) emissions in 2012, with 39% of these emissions arising from chemical/organic fertilizers in the form of nitrous oxide (N2O). Switching from calcium ammonium nitrate (CAN) to a urea based fertiliser limits the soil residence period of nitrate, the major substrate for denitrification loss in the N2O form. However, urea is susceptible to ammonia (NH3) volatilisation but this risk can be managed using urease inhibitors. The aim of this study was to evaluate the effect of switching from CAN to urea, urea with the urease inhibitor N- (n-butyl) thiophosphoric triamide (trade name Agrotain®) and/or the nitrification inhibitor dicyandiamide (DCD on direct and indirect N2O emissions. The experiment is a two year study (commenced March 2013) at six permanent pasture sites located on the island of Ireland, at Johnstown Castle Co. Wexford, Moorepark Co. Cork and Hillsborough Co. Down, covering a range of soil textures and drainage characteristics. The experiment simulated a grazing environment; annual fertiliser N was applied at different rates (0, 100, 200, 300, 400 or 500 kg N ha-1) in five equal splits, with grass harvested prior to fertilizer application. Direct N2O emissions were quantified regularly using static chambers over 1 year and indirect N2O from ammonia volatilisation was measured using wind tunnels and annual emission factors calculated. Switching from CAN to urea dramatically reduced direct N2O emissions, but had little effect on dry-matter yield. However, there was evidence of pollution swapping of direct for indirect N2O from NH3. In the first year, two urea based formulations successfully reduced both direct and indirect N2O emissions at all sites. Fertiliser formulation strategy has the potential to be a solution for reduction of direct and indirect N2O emissions.

  20. Subsurface N cycling under variable paddy flood management: what role does it play in N2O emissions?

    Science.gov (United States)

    Verhoeven, Elizabeth; Pierreux, Sofie; Decock, Charlotte; Romani, Marco; Sleutel, Steven; Six, Johan

    2016-04-01

    There is increasing pressure to grow rice with less water in order to save water and mitigate methane (CH4) emissions. However, there is frequently a trade-off with yield declines and increased nitrous oxide (N2O) emissions, potentially increasing the global warming potential of the system. A field trial in Northern Italy was established with two water regimes: continuously flooded (flooded) and alternate wetting and drying (AWD), to investigate the impact of such water management on N2O emissions and N cycling along a depth profile. Surface gas fluxes were complimented by depth profile measurements of soil gas, inorganic N, DOC, dissolved gas concentrations, redox potential and moisture. Sampling was concentrated around two periods during the 2015 growing season which were hypothesized to show significant variation in N dynamics; a fertilization event and final season drainage. For N cycling and N2O emissions, stable isotope measurements were taken to obtain process-level information in situ. During the first field campaign, maximum mean daily N2O emissions did not peak at fertilization but rather a week earlier, demonstrating a greater response to soil conditions (i.e. higher redox and lower moisture) than inorganic N concentrations. This was especially the case in the AWD treatment where emissions peaked at 82.3 ± 126.0 g N2O-N ha-1 d-1 relative to a peak of 2.83 ± 1.1 g N2O-N ha-1 d-1 in the flooded treatment. Considering the upper depths (0-15 cm), peak emissions corresponded well to higher redox potentials in the AWD treatment (72-406 mV versus -100 to -12 mV for AWD and flooded treatments, respectively). These emissions also correlated well to pore space N2O concentrations at 5 and 12.5 cm, suggesting important production of N2O at these depths and subsequent diffusion to the soil surface. Pore space and dissolved N2O concentrations were much lower in the flooded treatment and no such spikes were observed. No significant N2O emissions were observed in

  1. Nitrification and N2O production processes in soil incubations after ammonium fertilizer application at high concentrations

    Science.gov (United States)

    Deppe, Marianna; Well, Reinhard; Giesemann, Anette; Flessa, Heinz

    2016-04-01

    High concentrations of ammonium as they occur, e.g., after point-injection of ammonium fertilizer solution according to the CULTAN fertilization technique may retard nitrification. Potential advantages in comparison to conventional fertilization include a higher N efficiency of crops, reduced nitrate leaching, and lower N2O and N2 emissions. Dynamics of nitrification due to plant uptake and dilution processes, leading to decreasing ammonium concentrations in fertilizer depots, has only poorly been studied before. Furthermore, there is little information about the relative contribution of different N2O production processes under these conditions. To elucidate the process dynamics a laboratory incubation study was conducted. After fertilization with ammonium sulfate at 5 levels (from 0 to 5000 mg NH4+-N kg-1; 20mg NO3--N kg-1 each), sandy loam soil was incubated in dynamic soil microcosms for 21 days. N2O, CH4 and CO2 fluxes as well as isotope signatures of N2O and, at three dates, NO3- and NH4+ were measured. To identify N2O production processes, acetylene inhibition (0.01 vol.%), 15N tracer approaches, and isotopomer data (15N site preference and δ18O) were used. N2O emissions were highest at 450mg NH4+-N kg-1 and declined with further increasing concentrations. At 5000 mg NH4+-N kg-1 nitrification was completely inhibited. However, approximately 90% of N2O production was inhibited by acetylene application, and there was no change in the relative contribution of nitrification and denitrification to N2O production with N level. Applying the non-equilibrium technique to our 15N tracer data revealed heterogeneous distribution of denitrification in soil, with at least two distinct NO3- pools, and spatial separation of NO3- formation and consumption. In comparison with the acetylene inhibition and 15N tracer approaches the results of the isotopomer approach were reasonable and indicated substantial contribution of nitrifier-denitrification (10-40%) to total N2O

  2. 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.

  3. Oceanic N2O emissions in the 21st century

    Directory of Open Access Journals (Sweden)

    J. Martinez-Rey

    2014-12-01

    Full Text Available 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.

  4. Effect of assessment scale on spatial and temporal variations in CH4, C02, and N20 fluxes in a forested wetland

    Science.gov (United States)

    Zhaohua Dai; Carl Trettin; Changsheng Li; Harbin Li; Ge Sun; Devendra Amatya

    2011-01-01

    Emissions of methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) from a forested watershed (160 ha) in South Carolina, USA, were estimated with a spatially explicit watershed-scale modeling framework that utilizes the spatial variations in physical and biogeochemical characteristics across watersheds. The target watershed (WS80) consisting of wetland (23%) and...

  5. Isotopologue fractionation during N(2)O production by fungal denitrification.

    Science.gov (United States)

    Sutka, Robin L; Adams, Gerard C; Ostrom, Nathaniel E; Ostrom, Peggy H

    2008-12-01

    Identifying the importance of fungi to nitrous oxide (N2O) production requires a non-intrusive method for differentiating between fungal and bacterial N2O production such as natural abundance stable isotopes. We compare the isotopologue composition of N2O produced during nitrite reduction by the fungal denitrifiers Fusarium oxysporum and Cylindrocarpon tonkinense with published data for N2O production during bacterial nitrification and denitrification. The fractionation factors for bulk nitrogen isotope values for fungal denitrification were in the range -74.7 to -6.6 per thousand. There was an inverse relationship between the absolute value of the fractionation factors and the reaction rate constant. We interpret this in terms of variation in the relative importance of the rate constants for diffusion and enzymatic reduction in controlling the net isotope effect for N2O production during fungal denitrification. Over the course of nitrite reduction, the delta(18)O values for N2O remained constant and did not exhibit a relationship with the concentration characteristic of an isotope effect. This probably reflects isotopic exchange with water. Similar to the delta(18)O data, the site preference (SP; the difference in delta(15)N between the central and outer N atoms in N2O) was unrelated to concentration during nitrite reduction and, therefore, has the potential to act as a conservative tracer of production from fungal denitrification. The SP values of N2O produced by F. oxysporum and C. tonkinense were 37.1 +/- 2.5 per thousand and 36.9 +/- 2.8 per thousand, respectively. These SP values are similar to those obtained in pure culture studies of bacterial nitrification but quite distinct from SP values for bacterial denitrification. The large magnitude of the bulk nitrogen isotope fractionation and the delta(18)O values associated with fungal denitrification are distinct from bacterial production pathways; thus multiple isotopologue data holds much promise for

  6. 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...

  7. Validation of a station-prototype designed to integrate temporally soil N2O fluxes: IPNOA Station prototype.

    Science.gov (United States)

    Laville, Patricia; Volpi, Iride; Bosco, Simona; Virgili, Giorgio; Neri, Simone; Continanza, Davide; Bonari, Enrico

    2016-04-01

    Nitrous oxide (N2O) flux measurements from agricultural soil surface still accounts for the scientific community as major challenge. The evaluations of integrated soil N2O fluxes are difficult because these emissions are lower than for the other greenhouse gases sources (CO2, CH4). They are also sporadic, because highly dependent on few environmental conditions acting as limiting factors. Within a LIFE project (IPNOA: LIFE11 ENV/IT/00032) a station prototype was developed to integrate annually N2O and CO2 emissions using automatically chamber technique. Main challenge was to develop a device enough durable to be able of measuring in continuous way CO2 and N2O fluxes with sufficient sensitivity to allow make reliable assessments of soil GHG measurements with minimal technical field interventions. The IPNOA station prototype was developed by West System SRL and was set up during 2 years (2014 -2015) in an experimental maize field in Tuscan. The prototype involved six automatic chambers; the complete measurement cycle was of 2 hours. Each chamber was closing during 20 min and biogas accumulations were monitoring in line with IR spectrometers. Auxiliary's measurements including soil temperatures and water contents as weather data were also monitoring. All data were managed remotely with the same acquisition software installed in the prototype control unit. The operation of the prototype during the two cropping years allowed testing its major features: its ability to evaluate the temporal variation of N2O soil fluxes during a long period with weather conditions and agricultural managements and to prove the interest to have continuous measurements of fluxes. The temporal distribution of N2O fluxes indicated that emissions can be very large and discontinuous over short periods less ten days and that during about 70% of the time N2O fluxes were around detection limit of the instrumentation, evaluated to 2 ng N ha-1 day-1. N2O emission factor assessments were 1.9% in 2014

  8. 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 variations....... The moderate N2O fluxes and their moderate response to slurry application were attributed to dry soil moisture conditions due to the absence of rain fall during the previous four weeks. During the equivalent spring period of 2008, N2O fluxes were higher than in 2009, as was soil moisture content, indicating...

  9. Photoionization and fragmentaton of (N2O)n clusters

    Science.gov (United States)

    Kamke, W.; Kamke, B.; Kiefl, H. U.; Hertel, I. V.

    1986-02-01

    A supersonic molecular beam and monochromatized synchrotron radiation are presently used to measure photoionization efficiency curves for (N2O)n, at n = 1-6, in the 55-110 nm wavelength region. By measuring the energy loss of cluster ions which fragment in a field free drift region of the ion source, it becomes possible to detect delayed unimolecular and collision-induced fragmentations of the cluster ions. From a study of the dependence of the 'metastable' signals on background pressure, it appears that only the removal of a single N2O molecule at a time can occur by unimolecular decay.

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

    Science.gov (United States)

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

    2009-01-01

    In order to determine if the δ15N and δ18O values of N2O produced during co-oxidation of NH4+ by methanotrophic (methane oxidizing) bacteria can be isotopically distinguished from N2O produced either by autotrophic nitrifying or denitrifying bacteria, we conducted laboratory incubation experiments with pure cultures of methanotrophic bacteria that were provided NH4Cl as an oxidation substrate. The N2O produced during NH4+ oxidation by methanotrophic bacteria showed nitrogen isotope fractionation between NH4+ and N2O (εN2O–NH4+) of − 48 and − 55‰ for Methylomonas methanica and Methylosinus trichosporium, OB3b respectively. These large fractionations are similar to those previously measured for autotrophic nitrifying bacteria and consistent with N2O formation by multiple rate limiting steps that include NH4+oxidation by the methane monooxygenase enzyme and reduction of NO2− to N2O. Consequently, N2O formed by NH4+ oxidation via methanotrophic or autotrophic nitrifying bacteria might generally be characterized by lower δ15NN2O values than that formed by denitrificaiton, although this also depends on the variability of δ15N of available nitrogen sources (e.g., NH4+, NO3−, NO2−). Additional incubations with M. trichosporium OB3b at high and low CH4 conditions in waters of different δ18O values revealed that 19–27% of the oxygen in N2O was derived from O2 with the remainder from water. The biochemical mechanisms that could explain this amount of O2 incorporation are discussed. The δ18O of N2O formed under high CH4 conditions was ~ + 15‰ more positive than that formed under lower CH4 conditions. This enrichment resulted in part from the incorporation of O2 into N2O that was enriched in 18O due to an isotope fractionation effect of − 16.1 ± 2.0‰ and − 17.5 ± 5.4‰ associated with O2 consumption during the high and low methane concentration incubations, respectively. Therefore, N2O formed by NH4+

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

    Science.gov (United States)

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

    2011-05-01

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

  12. 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

  13. Global and regional emissions estimates for N2O

    Directory of Open Access Journals (Sweden)

    E. Saikawa

    2013-07-01

    Full Text Available 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 discrete air samples collected 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 for 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 % yr-1, 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 yr 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 the recent

  14. Tracing changes in soil N transformations to explain the doubling of N2O emissions under elevated CO2 in the Giessen FACE

    Science.gov (United States)

    Moser, Gerald; Brenzinger, Kristof; Gorenflo, Andre; Clough, Tim; Braker, Gesche; Müller, Christoph

    2017-04-01

    To reduce the emissions of greenhouse gases (CO2, CH4 & N2O) it is important to quantify main sources and identify the respective ecosystem processes. While the main sources of N2O emissions in agro-ecosystems under current conditions are well known, the influence of a projected higher level of CO2 on the main ecosystem processes responsible for N2O emissions has not been investigated in detail. A major result of the Giessen FACE in a managed temperate grassland was that a +20% CO2 level caused a positive feedback due to increased emissions of N2O to 221% related to control condition. To be able to trace the sources of additional N2O emissions a 15N tracing study was conducted. We measured the N2O emission and its 15N signature, together with the 15N signature of soil and plant samples. The results were analyzed using a 15N tracing model which quantified the main changes in N transformation rates under elevated CO2. Directly after 15N fertilizer application a much higher dynamic of N transformations was observed than in the long run. Absolute mineralisation and DNRA rates were lower under elevated CO2 in the short term but higher in the long term. During the one year study period beginning with the 15N labelling a 1.8-fold increase of N2O emissions occurred under elevated CO2. The source of increased N2O was associated with NO3- in the first weeks after 15N application. Elevated CO2 affected denitrification rates, which resulted in increased N2O emissions due to a change of gene transcription rates (nosZ/(nirK+nirS)) and resulting enzyme activity (see: Brenzinger et al.). Here we show that the reported enhanced N2O emissions for the first 8 FACE years do prevail even in the long-term (> 15 years). The effect of elevated CO2 on N2O production/emission can be explained by altered activity ratios within a stable microbial community.

  15. Wavelength dependence of isotope fractionation in N2O photolysis

    Directory of Open Access Journals (Sweden)

    P. J. Crutzen

    2002-10-01

    Full Text Available In previous reports on isotopic fractionation in the ultraviolet photolysis of nitrous oxide (N2O only enrichments of heavy isotopes in the remaining N2O fraction have been found. However, most direct photolysis experiments have been performed at wavelengths far from the absorption maximum at 182 nm. Here we present high-precision measurements of the 15N and 18O fractionation constants (e in photolysis at 185 nm. Small, but statistically robust depletions of heavy isotopes for the terminal atoms in the linear N2O molecule are found. This means that the absorption cross sections s(15N14N16O and s(14N218O are larger than s(14N216O at this specific wavelength. In contrast, the central N atom becomes enriched in 15N. The corresponding fractionation constants (±1 standard deviation are 15e1 = s(15N14N16O/s(14N216O - 1 = (3.7 ± 0.2%o 18e = s(14N218O/s(14N216O - 1 = (4.5 ± 0.2%o  and   15e2 = s(chem{14N15N16O/s(14N216O - 1 = (-18.6 ± 0.5 %o To our knowledge, this is the first documented case of such a heavy isotope depletion in the photolysis of N2O which supports theoretical models and pioneering vacuum ultraviolet spectroscopic measurements of 15N substituted N2O species that predict fluctuations of e around zero in this spectral region (Selwyn and Johnston, 1981. Such a variability in isotopic fractionation could have consequences for atmospheric models of N2O isotopes since actinic flux varies also strongly over narrow wavelength regions between 175 and 200 nm due to the Schumann-Runge bands of oxygen. However, the spacing between maxima and minima of the fractionation constants and of the actinic flux differ by two orders of magnitude in the wavelength  domain. The wavelength dependence of fractionation constants in N2O photolysis can thus be approximated by a linear fit with negligible consequences on the actual value of the spectrally averaged fractionation constant. In order to establish this linear fit, additional measurements at

  16. Development of a New N2O/CO Cavity Ring-Down Spectrometer for sub-ppb Ambient Gas Monitoring

    Science.gov (United States)

    Leggett, G. A.; Saad, N.; Zhou, J.; Hoffnagle, J.; Fleck, D.

    2015-12-01

    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 3/4ths 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 that was recently developed to measure sub-ppb ambient concentrations of two key greenhouse gas species, N2O and CO, simultaneously. It combines a quantum cascade laser with a proprietary 3-mirror optical cavity. The new optical analyzer was set up to monitor nitrous oxide and carbon monoxide, along with CO2 and CH4, in ambient air obtained from a 10m tower in Santa Clara, California. In the data collected, the contribution from traffic and a nearby sewage treatment facility was evident.

  17. 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.

  18. Effect of phosphogypsum and dicyandiamide as additives on NH3, N20 and CH4 emissions during composting.

    Science.gov (United States)

    Luo, Yiming; Li, Guoxue; Luo, Wenhai; Schuchardt, Frank; Jiang, Tao; Xu, Degang

    2013-07-01

    A laboratory scale experiment of composting in a forced aeration system using pig manure with cornstalks was carried out to investigate the effects of both phosphogypsum and dicyandiamide (DCD, C2H4N4) as additives on gaseous emissions and compost quality. Besides a control, there were three amended treatments with different amounts of additives. The results indicated that the phosphogypsum addition at the rate of 10% of mixture dry weight decreased NH3 and CH4 emissions significantly during composting. The addition of DCD at the rate of 0.2% of mixture dry weight together with 10% of phosphogypsum further reduced the N2O emission by affecting the nitrification process. Reducing the phosphogypsum addition to 5% in the presence of 0.2% DCD moderately increased the NH3 emissions but not N2O emission. The additives increased the ammonium content and electrical conductivity significantly in the final compost. No adverse effect on organic matter degradation or the germination index of the compost was found in the amended treatments. It was recommended that phosphogypsum and DCD could be used in composting for the purpose of reducing NH3, CH4 and N2O emissions. Optimal conditions and dose of DCD additive during composting should be determined with different materials and composting systems in further study.

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

    Science.gov (United States)

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

    2016-12-01

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

  20. Is CH4 consumption by soils controlled by physics or biology? Results from a study of plot-scale variability of greenhouse gas fluxes

    Science.gov (United States)

    Maier, Martin; Paulus, Sinikka; Nicolai, Clara; Nauer, Philipp

    2017-04-01

    Soil-atmosphere fluxes of trace gases vary on different spatial scales, between landscapes and ecosystems down to the plot scale within apparently homogenous sites. The production and consumption of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) underlie different spatial and temporal changes, und thus, their interrelation is difficult to unravel. Small-scale variability in soil properties is well-known from soil surveys, affecting theoretically water availability for plants, soil aeration, vegetation, the local photosynthesis rate, and, eventually, greenhouse gas fluxes. We investigated the small scale variability of greenhouse gas fluxes in a homogenous Scots Pine stand in a former riparian flood plain. Soil-atmosphere fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) were carried out at 60 points on a 250 m2 plot with strata of diverse soil substrates and understory vegetation. Gas flux measurements were combined with soil physical lab measurements, and a soil vegetation survey. The soil was a source of CO2 and a sink for CH4 and N2O. No correlations between the fluxes and only weak correlations between the fluxes and soil physical factors were observed. CH4 and CO2 fluxes were significantly different for the soil-vegetation strata. Separating the dataset into the different soil-vegetation strata showed that CH4 consumption increased significantly with soil gas diffusivity and soil respiration. Methane consumption in the silt stratum was higher at a given soil gas diffusivity than in the sand stratum, indicating a higher methanotrophic microbe population and thus better habitats in silt. CH4 consumption increased with soil respiration in all strata, so that we speculate that the rhizosphere and decomposing organic litter (as origin of most of the soil respiration) facilitate a preferred habitat of methanotrophic microbes. The patterns of N2O consumption were more complex, but consumption seemed to be limited at locations with

  1. On the optimisation of trace gas measurements : A new method for in situ measurements of CO2, CH4, CO, SF6 and N2O

    NARCIS (Netherlands)

    Laan van der, Sander

    2005-01-01

    The release of anthropogenic greenhouse gases into the earth’s atmosphere is by far the largest uncontrolled experiment in the history of the earth. Mankind is drastically modifying the composition of the atmosphere, both in greenhouse gases and aerosols

  2. Feeding the world's increasing population while limiting climate change impacts; decoupling agriculture' s N2O and CH4 emissions from population growth

    NARCIS (Netherlands)

    Beek, C.L.; Meerburg, B.G.; Schils, R.L.M.; Verhagen, J.; Kuikman, P.J.

    2010-01-01

    The global demand for agricultural products, including food, is rapidly increasing due to population growth and shifts in consumption patterns. The required increase in agricultural production is predominantly to be achieved in countries with relatively low agricultural production levels at present.

  3. Modeling N2O Reduction and Decomposition in a Circulating Fluidized bed Boiler

    DEFF Research Database (Denmark)

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

    1996-01-01

    The N2O concentration was measured in a circulating fluidized bed boiler of commercial size. Kinetics for N2O reduction by char and catalytic reduction and decomposition over bed material from the combustor were determined in a laboratory fixed bed reactor. The destruction rate of N2O in the comb......The N2O concentration was measured in a circulating fluidized bed boiler of commercial size. Kinetics for N2O reduction by char and catalytic reduction and decomposition over bed material from the combustor were determined in a laboratory fixed bed reactor. The destruction rate of N2O...

  4. Unusual reaction paths of SN2 nucleophile substitution reactions CH4 + H- → CH4 + H- and CH4 + F- → CH3F + H-: Quantum chemical calculations

    Science.gov (United States)

    Minyaev, Ruslan M.; Quapp, Wolfgang; Schmidt, Benjamin; Getmanskii, Ilya V.; Koval, Vitaliy V.

    2013-11-01

    Quantum chemical (CCSD(full)/6-311++G(3df,3pd), CCSD(T)(full)/6-311++G(3df,3pd)) and density function theory (B3LYP/6-311++G(3df,3pd)) calculations were performed for the SN2 nucleophile substitution reactions CH4 + H- → CH4 + H- and CH4 + F- → CH3F + H-. The calculated gradient reaction pathways for both reactions have an unusual behavior. An unusual stationary point of index 2 lies on the gradient reaction path. Using Newton trajectories for the reaction path, we can detect VRI point at which the reaction path branches.

  5. Isotopic signatures of anthropogenic CH4 sources in Alberta, Canada

    Science.gov (United States)

    Lopez, M.; Sherwood, O. A.; Dlugokencky, E. J.; Kessler, R.; Giroux, L.; Worthy, D. E. J.

    2017-09-01

    A mobile system was used for continuous ambient measurements of stable CH4 isotopes (12CH4 and 13CH4) and ethane (C2H6). This system was used during a winter mobile campaign to investigate the CH4 isotopic signatures and the C2H6/CH4 ratios of the main anthropogenic sources of CH4 in the Canadian province of Alberta. Individual signatures were derived from δ13CH4 and C2H6 measurements in plumes arriving from identifiable single sources. Methane emissions from beef cattle feedlots (n = 2) and landfill (n = 1) had δ13CH4 signatures of -66.7 ± 2.4‰ and -55.3 ± 0.2‰, respectively. The CH4 emissions associated with the oil or gas industry had distinct δ13CH4 signatures, depending on the formation process. Emissions from oil storage tanks (n = 5) had δ13CH4 signatures ranging from -54.9 ± 2.9‰ to -60.6 ± 0.6‰ and non-detectable C2H6, characteristic of secondary microbial methanogenesis in oil-bearing reservoirs. In contrast, CH4 emissions associated with natural gas facilities (n = 8) had δ13CH4 signatures ranging from -41.7 ± 0.7‰ to -49.7 ± 0.7‰ and C2H6/CH4 molar ratios of 0.10 for raw natural gas to 0.04 for processed/refined natural gas, consistent with thermogenic origins. These isotopic signatures and C2H6/CH4 ratios have been used for source discrimination in the weekly atmospheric measurements of stable CH4 isotopes over a two-month winter period at the Lac La Biche (LLB) measurement station, located in Alberta, approximately 200 km northeast of Edmonton. The average signature of -59.5 ± 1.4‰ observed at LLB is likely associated with transport of air after passing over oil industry sources located south of the station.

  6. 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...

  7. Identifying N2O formation and emissions from a full-scale partial nitritation reactor.

    Science.gov (United States)

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

    2016-01-01

    In this study, N2O formation and emissions from a full-scale partial nitritation (SHARON) reactor were identified through a three-weeks monitoring campaign during which the off-gas was analysed for N2O, O2, CO2 and NO. The overall N2O emission was 3.7% of the incoming ammonium load. By fitting the N2O emission to a theoretical gas stripping profile, the N2O emissions could be assigned to aerobically formed N2O and N2O formed under anoxic conditions. This was further substantiated by liquid N2O measurements. Under standard operation, 70% of the N2O emission was attributed to anoxic N2O formation. Dedicated experiments revealed that low dissolved oxygen concentrations (<1.0 gO2·m(-3)) and longer anoxic periods resulted in an increased N2O emission. Minimising or avoiding anoxic conditions has the highest effect in lowering the N2O emissions. As an additional result, the use of the off-gas N2O concentration measurements to monitor the gas-liquid mass transfer rate coefficient (kLa) during dynamic reactor operation was demonstrated.

  8. CH4 Flux Inversion Studies for Future Active Space CH4 Missions like MERLIN

    Science.gov (United States)

    Heimann, M.; Marshall, J.

    2011-12-01

    Space based active sensors such as the planned German-French CH4 DIAL MERLIN mission have a very small footprint and therefore see through moderately small cloud holes. This fact, in addition to being independent of reflected sunlight is expected to provide global coverage with a higher number of observations than heretofore possible with passive sensors. How will this impact our ability to infer the different types of CH4 surface sources? Using a global atmospheric inversion system we quantify the resulting error reduction of inferred CH4 source estimates as a function of spatial and temporal resolution given instrument accuracy and other parameters of potential satellite orbits. The methodology is based on the classical Green's function approach on a monthly global 8°x10° resolution (Houweling et al., 2004) extended by using a nested two-step procedure for the investigation of higher temporal and spatial source resolutions (Rödenbeck et al., 2009). We furthermore employ a nested Lagrangian system at very high resolution (down to 1/8° x 1/12°) to quantify the impact on the detection and quantification of point sources such as power plants, landfills, natural gas pipelines, forest fires, geological seeps, and volcanoes. We demonstrate that the current specification of the MERLIN DIAL mission with a nominal breakthrough instrument precision of 18 ppb and bias of 3 ppb over 50km would lead to a substantial improvement of CH4 source quantification in many regions of the world as compared to what is possible with the currently existing observations from the surface network or passive satellite sensors. Houweling, S, FM Breon, I Aben, C Roedenbeck, M Gloor, M Heimann, and P Ciais. 2004. "Inverse modeling of CO2 sources and sinks using satellite data: a synthetic inter-comparison of measurement techniques and their performance as a function of space and time." Atmospheric Chemistry And Physics 4: 523-538. Roedenbeck, C, C Gerbig, K Trusilova, and M Heimann. 2009. "A

  9. First real-time measurements of N2O isotopic signatures above intensively managed grassland: analytical performance, validation and illustrative examples

    Science.gov (United States)

    Wolf, Benjamin; Tuzson, Béla; Merbold, Lutz; Decock, Charlotte; Emmenegger, Lukas; Mohn, Joachim

    2014-05-01

    , and nitrate concentrations made the identification of controls on N2O isotopic composition possible. Furthermore, simultaneous eddy-covariance N2O flux measurements (Merbold et al. 2014) were used to derive a flux-averaged isotopic signature of soil-emitted N2O of intensively managed grassland. In this context, the potential of the derived N2O isotopic signatures for partitioning of microbial source processes will be discussed in relation to available literature data. Merbold, L, W Eugster, J Stieger, M Zahniser, D Nelson and N Buchmann. 2014. 'Greenhouse gas budget (CO2, CH4 and N2O) of intensively managed grassland following restoration' Global Change Biology doi:10.1111/gcb.12518 Mohn, J, B Tuzson, A Manninen, N Yoshida, S Toyoda, W A Brand, and L Emmenegger. 2012. 'Site selective real-time measurements of atmospheric N2O isotopomers by laser spectroscopy.' Atmospheric Measurement Techniques 5(7): 1601-1609 Park, S, P Croteau, K A Boering, D M Etheridge, D Ferretti, P J Fraser, K-R Kim, P B Krummel, R L Langenfelds, T D van Ommen, L P Steele, and C M Trudinger. 2012. 'Trends and seasonal cycles in the isotopic composition of nitrous oxide since 1940.' Nature Geoscience 5(4): 261-265. Waechter, H, J Mohn, B Tuzson, L Emmenegger, and M W Sigrist. 2008. 'Determination of N2O isotopomers with quantum cascade laser based absorption spectroscopy.' Optics Express 16(12): 9239-44. Wunderlin, P, M Lehmann, H Siegrist, B Tuzson, A Joss, L Emmenegger, and J Mohn. 2013. 'Isotope signatures of N2O in a mixed microbial population system: Constraints on N2O producing pathways in wastewater treatment.' Environmental Science and Technology 47: 1339-48.

  10. 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 ...

  11. 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 fluidized bed combustion (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...

  12. 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

  13. N2O consumption by low-nitrogen soil and its regulation by water and oxygen

    NARCIS (Netherlands)

    Wu, D.M.; Dong, W.X.; Oenema, O.; Wang, Y.Y.; Trebs, I.; Hu, C.S.

    2013-01-01

    Soils can be a source and sink for atmospheric nitrous oxide (N2O). Consumption of N2O has been reported for anoxic soils and sediments rich in organic matter and depleted in nitrates (NO3-), and also for some dry, oxic soils. However, the mechanisms and controls of N2O consumption in dry soil are n

  14. Determination of potential N2O-reductase activity in soil

    NARCIS (Netherlands)

    Qin, S.P.; Yuan, H.J.; Hu, C.S.; Oenema, O.; Zhang, Y.M.; Li, X.X.

    2014-01-01

    Determination of N2O-reductase activity in soil is important for understanding the microbial regulation of nitrous oxide (N2O) concentrations in soil. Unfortunately, there are no easily applicable and accurate methods for determining N2O-reductase activity, which frustrates the understanding of the

  15. Potential N2O Emissions from the Tanks of Bromeliads Suggest an Additional Source of N2O in the Neotropics.

    Science.gov (United States)

    Suleiman, Marcel; Brandt, Franziska B; Brenzinger, Kristof; Martinson, Guntars O; Braker, Gesche

    2016-12-06

    We studied the propensity of the tank bromeliad Werauhia gladioliflora to emit the greenhouse gas nitrous oxide (N2O) at current and at increased N deposition levels in the range of predicted future scenarios. Potential production rates and net accumulation of N2O from tank substrate corresponded to N availability. N2O was produced in excess at all N levels due to a low level of N2O reductase activity which agreed well with a low abundance of N2O reducers compared to nitrite reducers. Transcriptional activation, however, indicated that expression of denitrification genes may be enhanced with increasing N supply eventually leading to more efficient N2O turnover with potential for adaptation of denitrifier communities to higher N levels. Our findings indicate that tank bromeliads may constitute a novel source of N2O in Neotropical forest canopies but further studies are required to understand the size and significance of in situ N2O fluxes from tank bromeliads to the environment.

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

    DEFF Research Database (Denmark)

    Jensen, Lars Liengård; Nielsen, Lars Peter; Revsbech, Niels Peter;

    2013-01-01

    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...... 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....

  17. A consilience model to describe N2O production during biological N removal

    DEFF Research Database (Denmark)

    Domingo Felez, Carlos; Smets, Barth F.

    2016-01-01

    (NO) and N2O dynamics have been proposed. Here, a first comprehensive model that considers all relevant NO and N2O production and consumption mechanisms is proposed. The model describes autotrophic NO production by ammonia oxidizing bacteria associated with ammonia oxidation and with nitrite reduction......Nitrous oxide (N2O), a potent greenhouse gas, is produced during biological nitrogen conversion in wastewater treatment operations. Complex mechanisms underlie N2O production by autotrophic and heterotrophic organisms, which continue to be unravelled. Mathematical models that describe nitric oxide......, followed by NO reduction to N2O. It also considers NO and N2O as intermediates in heterotrophic denitrification in a 4-step model. Three biological NO and N2O production pathways are accounted for, improving the capabilities of existing models while not increasing their complexity. Abiotic contributions...

  18. 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.

  19. Regional N2O fluxes in Amazonia derived from aircraft vertical profiles

    Directory of Open Access Journals (Sweden)

    P. Tans

    2009-08-01

    Full Text Available Nitrous oxide (N2O is the third most important anthropogenic greenhouse gas. Globally, the main sources of N2O are nitrification and denitrification in soils. About two thirds of the soil emissions occur in the tropics and approximately 20% originate in wet rainforest ecosystems, like the Amazon forest. The work presented here involves aircraft vertical profiles of N2O from the surface to 4 km over two sites in the Eastern and Central Amazon: Tapajós National Forest (SAN and Cuieiras Biologic Reserve (MAN, and the estimation of N2O fluxes for regions upwind of these sites. To our knowledge, these regional scale N2O measurements in Amazonia are unique and represent a new approach to looking regional scale emissions. The fluxes upwind of MAN exhibited little seasonality, and the annual mean was 2.1±1.0 mg N2O m−2 day−1, higher than that for fluxes upwind of SAN, which averaged 1.5±1.6 mg N2O m−2 day−1. The higher rainfall around the MAN site could explain the higher N2O emissions. For fluxes from the coast to SAN seasonality is present for all years, with high fluxes in the months of March through May, and in November through December. The first peak of N2O flux is strongly associated with the wet season. The second peak of high N2O flux recorded at SAN occurs during the dry season and can not be easily explained. However, about half of the dry season profiles exhibit significant correlations with CO, indicating a larger than expected source of N2O from biomass burning. The average CO:N2O ratio for all profiles sampled during the dry season is 94±77 mol CO:mol N2O and suggests a larger biomass burning contribution to the global N2O budget than previously reported.

  20. Dissociative sticking of CH4 on Ru(0001)

    DEFF Research Database (Denmark)

    Nielsen, Jane Hvolbæk; Holmblad, Peter Mikal; Chorkendorff, Ib

    1999-01-01

    In this study the CH4 dissociation probability on Ru(0001) is found for various translational and vibrational energies. The absolute sticking values are determined from King and Wells experiments and carbon uptake curves. The carbon amount is determined from the recombination signal of carbon...... with oxygen obtained after the beam exposure when heating in an oxygen atmosphere. The measured sticking coefficient of CH4 is strongly enhanced both by increasing the translational and the vibrational energy of the CH4 molecule. A model is applied to the data and an estimate of the thermal activation energy...

  1. High Resolution CH4 Emissions and Dissolved CH4 Measurements Elucidate Surface Gas Exchange Processes in Toolik Lake, Arctic Alaska

    Science.gov (United States)

    Del Sontro, T.; Sollberger, S.; Kling, G. W.; Shaver, G. R.; Eugster, W.

    2013-12-01

    Approximately 14% of the Alaskan North Slope is covered in lakes of various sizes and depths. Diffusive carbon emissions (CH4 and CO2) from these lakes offset the tundra sink by ~20 %, but the offset would substantially increase if ebullitive CH4 emissions were also considered. Ultimately, arctic lake CH4 emissions are not insignificant in the global CH4 budget and their contribution is bound to increase due to impacts from climate change. Here we present high resolution CH4 emission data as measured via eddy covariance and a Los Gatos gas analyzer during the ice free period from Toolik Lake, a deep (20 m) Arctic lake located on the Alaskan North Slope, over the last few summers. Emissions are relatively low (Gatos gas analyzer. Thus, having both the flux and the CH4 gradient across the air-water interface measured directly, we can calculate k and investigate the processes influencing CH4 gas exchange in this lake. Preliminary results indicate that there are two regimes in wind speed that impact k - one at low wind speeds up to ~5 m s-1 and another at higher wind speeds (max ~10 m s-1). The differential wind speeds during night and day may compound the effect of convective mixing and cause the diurnal variation in observed fluxes.

  2. 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

    2016-06-01

    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.

  3. δ13C-CH4 in ice core samples

    DEFF Research Database (Denmark)

    Sperlich, Peter

    Ice core records of δ13C-CH4 reflect the variability of CH4 biogeochemistry in response to climate change and show this system is far more complex than expected. The first part of this work is concerned with the development of analytical techniques that allow 1) precise referencing and 2) measure......Ice core records of δ13C-CH4 reflect the variability of CH4 biogeochemistry in response to climate change and show this system is far more complex than expected. The first part of this work is concerned with the development of analytical techniques that allow 1) precise referencing and 2......) measurements of δ13C-CH4 in ice core samples as is required when δ13C-CH4 records that are measured in several laboratories are merged for analysis. Both the referencing and measurement techniques have been compared to further laboratories which proofed the accuracy of the analytical systems. The second part...

  4. δ13C-CH4 in ice core samples

    DEFF Research Database (Denmark)

    Sperlich, Peter

    Ice core records of δ13C-CH4 reflect the variability of CH4 biogeochemistry in response to climate change and show this system is far more complex than expected. The first part of this work is concerned with the development of analytical techniques that allow 1) precise referencing and 2) measure......Ice core records of δ13C-CH4 reflect the variability of CH4 biogeochemistry in response to climate change and show this system is far more complex than expected. The first part of this work is concerned with the development of analytical techniques that allow 1) precise referencing and 2......) measurements of δ13C-CH4 in ice core samples as is required when δ13C-CH4 records that are measured in several laboratories are merged for analysis. Both the referencing and measurement techniques have been compared to further laboratories which proofed the accuracy of the analytical systems. The second part...

  5. 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.

  6. Simple control strategy for mitigating N2O emissions in phase isolated full-scale WWTPs

    DEFF Research Database (Denmark)

    Ekström, Sara Elisabet Margareta; Vangsgaard, Anna Katrine; Lemaire, Romain

    2017-01-01

    removal processes relying on nitrification and denitrification are known to produce N2O. A one year long-term study of N2O production and emissions was performed at Lynetten, Denmark’s largest WWTP. Nitrification and denitrification takes place by alternating process conditions as well as influent...... and effluent flows in 20 pairs of interconnected and surface aerated reactors. The long-term data revealed that the N2O emissions contribute to as much as 30% of the total CO2 footprint from the WWTP. High ammonium concentrations and long aeration phases lead to high N2O production and emissions rates....... Nitrification phases were identified to produce and emit most of the N2O. High production and emissions were also associated with the afternoon loading peaks at the WWTP. During denitrification phases N2O was produced initially but consumed consequently. An effective control strategy was implemented, whereby N2...

  7. Spectroscopic Characterization of N_{2}O_{5} Halide Clusters and the Formation of HNO_{3}

    Science.gov (United States)

    Denton, Joanna K.; Kelleher, Patrick J.; Menges, Fabian; Johnson, Mark

    2017-06-01

    N_{2}O_{5} is an atmospheric species which serves as night-time sink for NO_{x} species. Its reconversion to NO_{x} products occurs through solvation in atmospheric aerosols. Detection of N_{2}O_{5} and NO_{3}^{-} fragmentation products in such aerosols has previously utilized chemical ionization featuring halides (of which chlorine is ubiquitous in sea-spray aerosols). We examine the solvation behavior of N_{2}O_{5} and the critical number of water molecules to form HNO_{3} from N_{2}O_{5} and water. We have been able to generate and spectroscopically characterize N_{2}O_{5}-halide ions formed from halide-water clusters. We observe X^{-}N_{2}O_{5} species whose spectra best correspond to a calculated (O_{2}NX)(ONO_{2}^{-}) species. Funding for this work was provided by the NSF's Center for Aerosol Impacts on Climate and the Environment.

  8. KlimaCH4. Climate effects of biomethane economy; KlimaCH4. Klimaeffekte von Biomethan

    Energy Technology Data Exchange (ETDEWEB)

    Westerkamp, Tanja; Reinelt, Torsten; Oehmichen, Katja; Ponitka, Jens; Naumann, Karin

    2014-07-01

    Within the project ''Climate effects of biomethane economy'' (KlimaCH4) of the German Biomass Research Centre two methods for measurement of direct greenhouse gas emissions were analyzed for their applicability and comparability. In the context of concrete measurements direct emissions, mainly of methane, three biogas plants with methane treatment for feeding into the natural gas grid were quantified. These tests were carried out on the one hand directly on-site by using leak detection, enclosures and ''open chamber'' measurements, but also indirectly by optical remote sensing with tunable diode laser absorption spectrometry (TDLAS) and reverse dispersion modelling by inverse dispersion modeling. The on-site method offers the possibility, to investigate the influences of plant operation on emissions of known diffuse sources, inter alia, through the balance of the operating status with the timeline of a specific emission source (e.g. as increased release of methane due to stirring intervals). This is particularly useful for deriving appropriate measures to reduce emissions. The quantification of individual, diffuse emission sources is metrologically possibly only very costly to implement. The effort is depending to a considerable extent by the design and the size of the examined biogas plant. In order to detect the influence seasonal changing of environmental conditions recurring emission measurements were realized. The use of optical telemetry showed as an advantageous alternative to on-site method, because it can significantly reduce time required for emission measurements particularly at large biogas plants or plants with numerous individual sources. With only one measurement sequence all emission sources are covered, without consuming individual measurements. In addition, in comparision to the on-site method, the emission situation of the entire system can be better reproduced, since all individual sources are included in

  9. KlimaCH4. Climate effects of biomethane economy; KlimaCH4. Klimaeffekte von Biomethan

    Energy Technology Data Exchange (ETDEWEB)

    Westerkamp, Tanja; Reinelt, Torsten; Oehmichen, Katja; Ponitka, Jens; Naumann, Karin

    2014-07-01

    Within the project ''Climate effects of biomethane economy'' (KlimaCH4) of the German Biomass Research Centre two methods for measurement of direct greenhouse gas emissions were analyzed for their applicability and comparability. In the context of concrete measurements direct emissions, mainly of methane, three biogas plants with methane treatment for feeding into the natural gas grid were quantified. These tests were carried out on the one hand directly on-site by using leak detection, enclosures and ''open chamber'' measurements, but also indirectly by optical remote sensing with tunable diode laser absorption spectrometry (TDLAS) and reverse dispersion modelling by inverse dispersion modeling. The on-site method offers the possibility, to investigate the influences of plant operation on emissions of known diffuse sources, inter alia, through the balance of the operating status with the timeline of a specific emission source (e.g. as increased release of methane due to stirring intervals). This is particularly useful for deriving appropriate measures to reduce emissions. The quantification of individual, diffuse emission sources is metrologically possibly only very costly to implement. The effort is depending to a considerable extent by the design and the size of the examined biogas plant. In order to detect the influence seasonal changing of environmental conditions recurring emission measurements were realized. The use of optical telemetry showed as an advantageous alternative to on-site method, because it can significantly reduce time required for emission measurements particularly at large biogas plants or plants with numerous individual sources. With only one measurement sequence all emission sources are covered, without consuming individual measurements. In addition, in comparision to the on-site method, the emission situation of the entire system can be better reproduced, since all individual sources are included in

  10. Contributions of agricultural plants and soils to N2O emission in a farmland

    Science.gov (United States)

    Li, J.; Lee, X.; Yu, Q.; Tong, X.; Qin, Z.; MacDonald, B.

    2011-06-01

    The goal of this study was to quantify the roles of plants and soil in the N2O budget of a cropland in North China. Plant and soil N2O fluxes were measured with transparent and dark plant chambers and soil chambers, respectively, in three adjacent fields of fertilized cotton, fertilized maize and unfertilized soybean. During the observation period, the soil flux was 448 ± 89, 230 ± 74 and 90 ± 14 μg N2O m-2 h-1 in cotton, maize and soybean fields, respectively. The plant flux was 54 ± 43 and 16 ± 41 μg N2O m-2 h-1, about 10 % and 26 % to the total ecosystem flux, for the cotton and the soybean field, respectively. Ignoring the contribution of plants would cause an obvious underestimation on the ecosystem N2O flux. The influence of sunlight on plant N2O flux was insignificant. However, in the cotton field, the responses of the plant N2O flux to air temperature and soil ammonium content were significant under sunlight but insignificant under darkness, suggesting that stomatal activity might influence the release process. In the cotton field, temperature sensitivity of plant N2O emission was 1.13, much lower than the value of soil flux (5.74). No relationship was found between plant N2O flux and soil nitrate content. It was implied that nitrate reduction in plants might not be the main source of plant N2O emission under field conditions. The seasonal patterns of the soil and plant N2O emissions were similarly affected by fertilization, indicating that plants might serve as a passive conduit transporting N2O produced in the soil.

  11. 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 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.

  12. Anoxic growth of Ensifer meliloti 1021 by N2O-reduction, a potential mitigation strategy

    Directory of Open Access Journals (Sweden)

    Emilio eBueno

    2015-05-01

    Full Text Available Denitrification in agricultural soils is a major source of N2O. Legume crops enhance N2O emission by providing N-rich residues, thereby stimulating denitrification, both by free-living denitrifying bacteria and by the symbiont (rhizobium within the nodules. However, there are limited data concerning N2O production and consumption by endosymbiotic bacteria associated with legume crops. It has been reported that the alfalfa endosymbiont Ensifer meliloti strain 1021, despite possessing and expressing the complete set of denitrification enzymes, is unable to grow via nitrate respiration under anoxic conditions. In the present study, we have demonstrated by using a robotized incubation system that this bacterium is able to grow through anaerobic respiration of N2O to N2. N2O reductase (N2OR activity was not dependent on the presence of nitrogen oxyanions or NO, thus the expression could be induced by oxygen depletion alone. When incubated at pH 6, E. meliloti was unable to reduce N2O, corroborating previous observations found in both, extracted soil bacteria and Paracoccus denitrificans pure cultures, where expression of functional N2O reductase is difficult at low pH. Furthermore, the presence in the medium of highly reduced C-substrates, such as butyrate, negatively affected N2OR activity. The emission of N2O from soils can be lowered if legumes plants are inoculated with rhizobial strains overexpressing N2O reductase. This study demonstrates that strains like E. meliloti 1021, which do not produce N2O but are able to reduce the N2O emitted by other organisms, could act as even better N2O sinks.

  13. A multi-scale approach to characterize pure CH4, CF4, and CH4/CF4 mixtures

    Science.gov (United States)

    Chattoraj, Joyjit; Risthaus, Tobias; Rubner, Oliver; Heuer, Andreas; Grimme, Stefan

    2015-04-01

    In this study, we develop three intermolecular potentials for methane (CH4), tetrafluoromethane (CF4), and CH4/CF4 dimers using a novel ab initio method. The ultimate goal is to understand microscopically the phase-separation in CH4/CF4 systems, which takes place in the liquid states near their freezing points. Monte-Carlo (MC) simulations of the pure CH4 system are performed using the ab initio energies to verify the potential. The simulations reproduce quite well the experimentally known liquid densities, the internal energies, the second virial coefficients, and the radial distribution function. The essentially six-dimensional (6D) ab initio potential is then reduced to a one-dimensional (1D) effective potential using the inverse Monte-Carlo technique. This potential, too, successfully reproduces the experimental results. Interestingly, the MC study cannot be extended to the pure CF4 system and the CH4/CF4 mixed system because the two respective ab initio potentials present very rough potential landscapes. This renders the interpolation of energies for the MC simulations and thus the multi-scale approach unreliable. It suggests, however, a possible driving force for the experimentally observed phase separation of the CH4/CF4 system at low temperatures. Furthermore, we carefully study the determination of 1D effective potentials via inverse MC techniques. We argue that to a good approximation the temperature dependence of the 1D potentials can be estimated via reweighting techniques for a fixed temperature.

  14. Nqrs Data for C6H16I2N2O8 [C6H14N2O2·2(HIO3)] (Subst. No. 0931)

    Science.gov (United States)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C6H16I2N2O8 [C6H14N2O2·2(HIO3)] (Subst. No. 0931)

  15. Nqrs Data for C6H17I3N2O11 [C6H14N2O2·3(HIO3)] (Subst. No. 0933)

    Science.gov (United States)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C6H17I3N2O11 [C6H14N2O2·3(HIO3)] (Subst. No. 0933)

  16. Nqrs Data for C6H20I6N2O20 [C6H14N2O2·6(HIO3)] (Subst. No. 0939)

    Science.gov (United States)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C6H20I6N2O20 [C6H14N2O2·6(HIO3)] (Subst. No. 0939)

  17. 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.

  18. The Earthworm Gut: an Ideal Habitat for Ingested N2O-Producing Microorganisms

    OpenAIRE

    Horn, Marcus A.; Schramm, Andreas; Drake, Harold L.

    2003-01-01

    The in vivo production of nitrous oxide (N2O) by earthworms is due to their gut microbiota, and it is hypothesized that the microenvironment of the gut activates ingested N2O-producing soil bacteria. In situ measurement of N2O and O2 with microsensors demonstrated that the earthworm gut is anoxic and the site of N2O production. The gut had a pH of 6.9 and an average water content of approximately 50%. The water content within the gut decreased from the anterior end to the posterior end. In co...

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

    Science.gov (United States)

    Kravchenko, A. N.; Toosi, E. R.; Guber, A. K.; Ostrom, N. E.; Yu, J.; Azeem, K.; Rivers, M. L.; Robertson, G. P.

    2017-07-01

    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 (∅ >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. 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

  1. Phylogenetic and functional potential links pH and N2O emissions in pasture soils

    Science.gov (United States)

    Samad, M. D. Sainur; Biswas, Ambarish; Bakken, Lars R.; Clough, Timothy J.; de Klein, Cecile A. M.; Richards, Karl G.; Lanigan, Gary J.; Morales, Sergio E.

    2016-10-01

    Denitrification is mediated by microbial, and physicochemical, processes leading to nitrogen loss via N2O and N2 emissions. Soil pH regulates the reduction of N2O to N2, however, it can also affect microbial community composition and functional potential. Here we simultaneously test the link between pH, community composition, and the N2O emission ratio (N2O/(NO + N2O + N2)) in 13 temperate pasture soils. Physicochemical analysis, gas kinetics, 16S rRNA amplicon sequencing, metagenomic and quantitative PCR (of denitrifier genes: nirS, nirK, nosZI and nosZII) analysis were carried out to characterize each soil. We found strong evidence linking pH to both N2O emission ratio and community changes. Soil pH was negatively associated with N2O emission ratio, while being positively associated with both community diversity and total denitrification gene (nir & nos) abundance. Abundance of nosZII was positively linked to pH, and negatively linked to N2O emissions. Our results confirm that pH imposes a general selective pressure on the entire community and that this results in changes in emission potential. Our data also support the general model that with increased microbial diversity efficiency increases, demonstrated in this study with lowered N2O emission ratio through more efficient conversion of N2O to N2.

  2. Decomposition and reduction of N2O on CaS (100) surface: A theoretical account

    Science.gov (United States)

    Wu, Lingnan; Qin, Wu; Hu, Xiaoying; Ju, Shaoda; Dong, Changqing; Yang, Yongping

    2015-02-01

    The catalytic effect of CaS on N2O decomposition and reduction was investigated using density functional theory calculations. N2O approached the CaS (100) surface and crossed an energy barrier of 1.228 eV, decomposing into a free N2 molecule and an adsorbed O atom. The generated adsorbed O atom could be removed through two reaction pathways: binding with a neighboring adsorbed O atom into O2 with the barrier energy of 1.877 eV or reacting with another N2O molecule generating an adsorbed O2 with the barrier of 1.863 eV. The removal of the surface adsorbed O atom is the rate-determining step of the catalytic decomposition of N2O. In comparison with the homogeneous reaction between N2O and CO, CO accelerated the removal of the adsorbed O atom, hence improving the reduction of N2O on CaS (100). Furthermore, while compared with the CaO-catalytic removal of N2O, CaS is not as active as CaO for the decomposition and reduction of N2O. Our study is the first attempt to theoretically reveal the mechanism of CaS-catalytic decomposition and reduction of N2O, which provides a better understanding of the nitrogen chemistry in the reducing atmosphere zone of circulating fluidized bed boilers.

  3. Investigation of nitrous oxide (N2O) abatement technologies. 2; Asanka chisso (N2O) no teigen taisaku ni kansuru chosa. 2

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    Emission amount of nitrous oxide (N2O) from anthropogenic sources is analyzed, and reduction effects by the abatement technologies are evaluated. The concentration of nitrous oxide in the atmosphere continues to increase and emissions from agricultural and ecosystem sources are drawing particular attention. For the emission of N2O in Japan, 8.28 Gg-N2O per year is emitted from fossil fuel combustion facilities, 6.95 from waste incineration facilities, 22.5 from transportation vehicles including automobiles, 26.7 from the chemical industry including establishments engaged in adipic acid production, 2.1 from sewage treatment facilities including septic tanks, 6.3 from farmland, and 7.1 from livestock excrement. For the N2O abatement technologies for different sources, fuel improvement, high temperature combustion, acceleration of reduction decomposition reaction, and development of catalysts are significant for the combustion technologies. In connection with N2O discharged in the process of adipic acid production, major businesses have internationally committed to up to 99% abatement of the N2O emissions by 1998. With regard to wastewater and sewage treatment facilities and septic tanks, improvement in COD/NO-N ratio, retention period, pH level, and reduction process is pointed out. 204 refs., 70 figs., 53 tabs.

  4. Fractal dimension of coal particles and their CH_4 adsorption

    Institute of Scientific and Technical Information of China (English)

    Wang; Chengyang; Hao; Shixiong; Sun; Wenjing; Chu; Wei

    2012-01-01

    We describe the fractal analysis of three differently sized coal samples(0.350-0.833 mm,0.245-0.350 mm,and 0.198-0.245 mm).The influence of fractal dimension on CH 4 adsorption capacity is investigated.The physical parameters of the samples were determined via the Brunauer-Emmett-Teller(BET) theory.A CH 4 adsorption study over the pressures range from 0 to 5 MPa was carried out with a new volumetric measurement system.The CH 4 adsorption was measured using the differently sized coal.Two fractal dimensions,D 1 and D 2 were determined over the pressure ranges from 0 to 0.5 MPa and from 0.5 to 1 MPa,using the Frenkel-Halsey-Hill(FHH) method.We conclude that the two fractal dimensions correlate with the CH 4 adsorption capacity of the coal:increasing CH 4 adsorption capacity occurs with a corresponding increase in fractal dimension.Furthermore,D 1 and D 2 are positively correlated with surface area,pore volume,and samples size.The size distribution of the samples has fractal characteristics.

  5. Isotopologue effects during N2O reduction in soils and in pure cultures of denitrifiers

    Science.gov (United States)

    Ostrom, Nathaniel E.; Pitt, Adam; Sutka, Robin; Ostrom, Peggy H.; Grandy, A. Stuart; Huizinga, Kristin M.; Robertson, G. Philip

    2007-06-01

    Site preference (SP), the difference in δ15N between the central and outer nitrogen atoms in N2O, is a powerful approach for apportioning fluxes of N2O from soils to nitrification and denitrification (Sutka et al., 2006). A critical aspect of the use of SP data to apportion sources of N2O to nitrification and denitrification is the need to evaluate data for isotope shifts that may have occurred during N2O reduction in soils prior to its escape to the atmosphere. We present data on the isotopologue effects during reduction of N2O during anaerobic incubation of soils and pure cultures of denitrifying bacteria. Isotopic enrichment factors for N2O reduction in soil mesocosms experiments varied between -9.2 and -1.8‰ for nitrogen and between -25.1 and -5.1‰ for oxygen. In pure cultures of Psuedomonas stutzeri and Psuedomonas denitrificans we observed isotopic enrichment factors for SP of -5.0 and -6.8‰, respectively. We further find that N2O consumption produces consistent relationships between δ18O and δ15N and δ18O and the δ15N of the central N atom in N2O of 2.5 and 1.6, respectively, which are clearly diagnostic of this process. Our results indicate that SP may be altered during reduction of N2O and thus bias evaluations of its origins. To understand the impacts of N2O reduction in soil flux studies on source isotope signals we modeled the isotope effects of N2O production occurring simultaneous with reduction and find increasingly curvilinear relationships between δ18O and δ15N and δ18O and δ15Nα with increased reduction. Consequently, a deviation from the linear mixing relationship between soil-derived and atmospheric N2O is an indication of extensive reduction. On the basis of our characterization of isotopic fractionation during N2O reduction, we show that the rate of reduction would have to be substantially greater than 10% of that of production to impact SP estimates of N2O from denitrification by more than a few percent. Nonetheless, reduction

  6. 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.

  7. High temporal resolution ecosystem CH4, CO2 and H2O flux data measured with a novel chamber technique

    Science.gov (United States)

    Steenberg Larsen, Klaus; Riis Christiansen, Jesper

    2016-04-01

    Soil-atmosphere exchange of greenhouse gases (GHGs) is commonly measured with closed static chambers (Pihlatie et al., 2013) with off-site gas chromatographic (GC) analysis for CH4 and N2O. Static chambers are widely used to observe in detail the effect of experimental manipulations, like climate change experiments, on GHG exchange (e.g. Carter et al., 2012). However, the low sensitivity of GC systems necessitates long measurement times and manual sampling, which increases the disturbance of the exchange of GHGs and leads to potential underestimation of fluxes (Christiansen et al., 2011; Creelman et al., 2013). The recent emergence of field proof infrared lasers using cavity ring-down spectroscopy (CRDS) have increased frequency and precision of concentration measurements and enabled better estimates of GHG fluxes (Christiansen et al., 2015) due to shorter chamber enclosure times. This minimizes the negative impact of the chamber enclosure on the soil-atmosphere gas exchange rate. Secondly, an integral aspect of understanding GHG exchange in terrestrial ecosystem is to achieve high temporal coverage. This is needed to capture the often dynamic behavior where fluxes can change rapidly over the course of days or even a few hours in response to e.g. rain events. Consequently, low temporal coverage in measurements of GHG exchange have in many past investigations led to highly uncertain annual budgets which severely limits our understanding of the ecosystem processes interacting with the climate system through GHG exchange. Real-time field measurements at high temporal resolution are needed to obtain a much more detailed understanding of the processes governing ecosystem CH4 exchange as well as for better predicting the effects of climate and environmental changes. We combined a state-of-the-art field applicable CH4 sensor (Los Gatos UGGA) with a newly developed ecosystem-level automatic chamber controlled by a LI-COR 8100/8150 system. The chamber is capable of

  8. Hot CH4 in the polar regions of Jupiter

    Science.gov (United States)

    Kim, Sang Joon; Sim, Chae Kyung; Ho, Jin; Geballe, Thomas R.; Yung, Yuk L.; Miller, Steve; Kim, Yong Ha

    2015-09-01

    We have obtained 3.3-3.4-μm spectro-images of Jupiter including CH4 and H3+ emission lines from both polar regions at the Gemini North telescope. We find that the peak of the 3-μm CH4 northern bright spot is located at ∼200° (SysIII) longitude, ∼20° west of the center of the 8-μm north-polar bright spot, and does not coincide with the 3-μm H3+ bright spot. We derive high temperatures (500-850 K) from CH4 rotational lines on the bright spots of both polar regions, above the 1-μbar pressure level, while we find cooler temperatures (Joule heating, in contrast with the 8-μm thermal emission.

  9. Vibrational transition moments of CH$_4$ from first principles

    CERN Document Server

    Yurchenko, Sergei N; Barber, Robert J; Thiel, Walter

    2013-01-01

    A new nine-dimensional (9D), \\textit{ab initio} electric dipole moment surface (DMS) of methane in its ground electronic state is presented. The DMS is computed using an explicitly correlated coupled cluster CCSD(T)-F12 method in conjunction with an F12-optimized correlation consistent basis set of the TZ-family. A symmetrized molecular bond representation is used to parameterise the 9D DMS in terms of sixth-order polynomials. Vibrational transition moments as well as band intensities for a large number of IR-active vibrational bands of $^{12}$CH$_4$ are computed by vibrationally averaging the \\textit{ab initio} dipole moment components. The vibrational wavefunctions required for these averages are computed variationally using the program TROVE and a new `spectroscopic' $^{12}$CH$_4$ potential energy surface. The new DMS will be used to produce a hot line list for $^{12}$CH$_4$.

  10. Real-time analysis of δ13C- and δD-CH4 in ambient air with laser spectroscopy: method development and first intercomparison results

    Directory of Open Access Journals (Sweden)

    S. Eyer

    2015-08-01

    Full Text Available In situ and simultaneous measurement of the three most abundant isotopologues of methane using mid-infrared laser absorption spectroscopy is demonstrated. A field-deployable, autonomous platform is realized by coupling a compact quantum cascade laser absorption spectrometer (QCLAS to a preconcentration unit, called TRace gas EXtractor (TREX. This unit enhances CH4 mole fractions by a factor of up to 500 above ambient levels and quantitatively separates interfering trace gases such as N2O and CO2. The analytical precision of the QCLAS isotope measurement on the preconcentrated (750 ppm, parts-per-million, μmole/mole methane is 0.1 and 0.5 ‰ for δ13C- and δD-CH4 at 10 min averaging time. Based on replicate measurements of compressed air during a two-week intercomparison campaign, the repeatability of the TREX-QCLAS was determined to be 0.19 and 1.9 ‰ for δ13C and δD-CH4, respectively. In this intercomparison campaign the new in situ technique is compared to isotope-ratio mass-spectrometry (IRMS based on glass flask and bag sampling and real time CH4 isotope analysis by two commercially available laser spectrometers. Both laser-based analyzers were limited to methane mole fraction and δ13C-CH4 analysis, and only one of them, a cavity ring down spectrometer, was capable to deliver meaningful data for the isotopic composition. After correcting for scale offsets, the average difference between TREX–QCLAS data and bag/flask sampling–IRMS values are within the extended WMO compatibility goals of 0.2 and 5 ‰ for δ13C- and δD-CH4, respectively. Thus, the intercomparison also reveals the need for reference air samples with accurately determined isotopic composition of CH4 to further improve the interlaboratory compatibility.

  11. Study of CH4 and CO oxidation from electrochemical method

    Institute of Scientific and Technical Information of China (English)

    ZHU Junjiang; YANG Xiangguang; XU Xuelian; WEI Kemei

    2006-01-01

    CH4 and CO oxidation reaction on perovskite-like oxides La2-xSrxMO4 (0.0≤x≤1.0; M = Cu, Ni) was investigated from cyclic voltammetry method, finding that for suprafacial CO oxidation reaction, the catalyst activity has a close correlation to the area of redox peaks measured in the cyclic voltammetry, the larger the peak area is, the higher the activity will be, while for interfacial CH4 oxidation reaction, the activity depends mainly on the difference in redox potentials (△E), and the smaller the difference in redox potentials is, the higher the activity will be.

  12. Macromolecule simulation and CH4 adsorption mechanism of coal vitrinite

    Science.gov (United States)

    Yu, Song; Yan-ming, Zhu; Wu, Li

    2017-02-01

    The microscopic mechanism of interactions between CH4 and coal macromolecules is of significant practical and theoretical importance in CBM development and methane storage. Under periodic boundary conditions, the optimal energy configuration of coal vitrinite, which has a higher torsion degree and tighter arrangement, can be determined by the calculation of molecular mechanics (MM) and molecular dynamics (MD), and annealing kinetics simulation based on ultimate analysis, 13C NMR, FT IR and HRTEM. Macromolecular stabilization is primarily due to the van der Waals energy and covalent bond energy, mainly consisting of bond torsion energy and bond angle energy. Using the optimal configuration as the adsorbent, GCMC simulation of vitrinite adsorption of CH4 is conducted. A saturated state is reached after absorbing 17 CH4s per coal vitrinite molecule. CH4 is preferentially adsorbed on the edge, and inclined to gathering around the branched chains of the inner vitrinite sites. Finally, the adsorption parameters are calculated through first principle DFT. The adsorbability order is as follows: aromatic structure> heteroatom rings > oxygen functional groups. The adsorption energy order is as follows: Top < Bond < Center, Up < Down. The order of average RDF better reflects the adsorption ability and that of [-COOH] is lower than those of [sbnd Cdbnd O] and [Csbnd Osbnd C]. CH4 distributed in the distance of 0.99-16 Å to functional groups in the type of monolayer adsorption and the average distance order manifest as [sbnd Cdbnd O] (1.64 Å) < [Csbnd Osbnd C] (1.89 Å) < [sbnd COOH] (3.78 Å) < [-CH3] (4.11 Å) according to the average RDF curves. CH4 enriches around [sbnd Cdbnd O] and [Csbnd O-C] whereas is rather dispersed about [-COOH] and [CH3]. Simulation and experiment data are both in strong agreement with the Langmuir and D-A isothermal adsorption model and the D-A model fit better than Langmuir model. Preferential adsorption sites and orientations in vitrinite are

  13. 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...

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

    DEFF Research Database (Denmark)

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

    2004-01-01

    trap with liquid nitrogen, which selectively removes any unreacted N2O from the gas. Nitrogen evolved by the oxidation reaction is not removed in the N2O trap and a binary mixture of nitrogen diluted in helium carrier gas is then measured accurately directly in a calibrated thermal conductivity...

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

    Science.gov (United States)

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

  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

    The addition of limestone for sulphur retention in Fluidized Bed Combustion (FBC) has been observed to influence the emission of N2O, and in many cases a lower emission was observed. The catalytic activity of a Danish limestone (Stevns Chalk) for decomposition of N2O in a laboratory fixed bed...

  17. Validation of the CO2/N2O analogy using molecular simulation

    NARCIS (Netherlands)

    Chen, Q.; Balaji, S.P.; Ramdin, M.; Gutiérrez-Sevillano, J.J.; Bardow, A.; Goetheer, E.L.V.; Vlugt, T.J.H.

    2014-01-01

    CO2 readily reacts in aqueous amine solutions. The properties of free CO2 in amine solutions are therefore difficult to obtain directly and are often predicted from the nonreacting molecule N2O due to the similarities in mass and structure. This often-used empirical "CO2/N2O analogy" is verified in

  18. 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".

  19. Enhanced Brewer Dobson circulation reduces N2O warming potential under climate change

    Science.gov (United States)

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

    2016-04-01

    One implication of climate change is an enhancement of the Brewer Dobson circulation (BDC) triggering the exchange between troposphere and stratosphere. This change in atmospheric dynamics will have effects on atmospheric constituents, especially those with stratospheric sinks such as ozone depleting substances (ODS) including nitrous oxide (N2O). N2O is the most important currently emitted ODS, and the third most important anthropogenic greenhouse gas. Under enhanced BDC, more N2O is transported from the troposphere into the stratosphere, reaching higher altitudes, resulting in an increased N2O sink and a decrease in N2O lifetime. Some aspects of the effect of an enhanced BDC on lifetimes of ODS have already been examined with focus on its implications for ozone. In this study, we examine the effect of a decreasing N2O lifetime in light of climate change. To this end we conduct idealized transient global warming simulations with ECHAM, the atmosphere component of the MPI Earth System Model. As we prescribe surface flux boundary conditions for N2O, we are able to examine further implications of an enhanced N2O sink on atmospheric abundance, which is an important factor for e.g. generating concentration scenarios. Due the idealized simulation setup, we derive findings that are scenario-independent and can easily be extended to other global warming scenarios.

  20. 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

  1. The Isotopomer Signal of N2O Produced From Biological Sources

    Science.gov (United States)

    Parkes, S. D.; Griffith, D. W.; Wilson, S. R.; Chen, D.; Mills, A. R.; Turner, D.

    2004-12-01

    Atmospheric concentrations of N2O have increased significantly since the industrial revolution; this is predominantly the result of the increasing nitrogen inputs to the biosphere. Although this is accepted as the major source of increasing atmospheric N2O, the uncertainty associated with the quantification of these emissions is quite large. This uncertainty is partly because of both the poor understanding of the biological mechanisms producing N2O, and their relative contributions to N2O emissions. Isotopic fractionation provides insight into the processes responsible for N2O emissions. Here we present measurements of the isotopic composition of N2O emitted from different sources. To provide an improved signal for the minor isotopomers (specifically 15N14N16O and 14N15N16O), some of the analysis sites were fertilised with substrate that was 10% 15N enriched, providing a 20 fold increase in the signal for the minor isotopes. Collection of samples involved the cryogenic trapping of N2O collected from the headspace of chambers over soil plots or estuarine sediments. The samples were analysed in the laboratory using high resolution FTIR spectrometry. The isotopomer measurements were augmented with soil parameters such as, nitrate and ammonium concentration, water filled pore space (WFPS) and pH. The combined measurements provide insight into the likely N2O production mechanisms.

  2. N 2, N 2O and O 2Profiles in a Tagus Estuary Salt Marsh

    Science.gov (United States)

    Cartaxana, P.; Lloyd, D.

    1999-06-01

    Vertical gas profiles of N 2, N 2O and O 2were obtained in intact sediment cores from a Tagus estuary salt marsh using membrane inlet mass spectrometry. This technique allows direct measurements of dissolved gas concentrations with minimal disturbance. O 2concentrations decreased sharply with depth, becoming undetectable below 14mm. Denitrification products (N 2and N 2O) occurred in the surface layer of the sediment where O 2was present. Diffusion of N 2and N 2O from the anaerobic zone, denitrification in anaerobic microsites and aerobic denitrification are possible explanations for this observation. N 2was the sole product of denitrification in control sediment cores probably because of the great demand for electron acceptors in this sediment. The addition of NO 3 - and CH 3CO 2 - increased the concentrations of N 2and N 2O in the sediment. Significantly higher concentrations in treated cores occurred between 1·5 and 2·0cm for N 2and between 0·5 and 1·5cm for N 2O. The peak in N 2concentration occurred in the anaerobic zone of the sediment, close to the aerobic-anaerobic interface while the peak in N 2O concentration occurred above this interface where concentrations of O 2were approximately 10μM. This is indicative that, in this sediment, production of N 2O is less sensitive to the presence of O 2than reduction of N 2O to N 2.

  3. 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 ani

  4. 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.

  5. Emissions of nitrous acid (HONO), nitric oxide (NO) and nitrous oxide (N2O) from boreal agricultural soil - Effect of N fertilization

    Science.gov (United States)

    Bhattarai, Hem Raj; Virkajärvi, Perttu; -Yli Pirilä, Pasi; Maljanen, Marja

    2017-04-01

    There is no doubt that nitrogen (N) fertilization has crucial role in increasing food production. However, in parallel it can cause severe impact in environment such as eutrophication, surface/groundwater pollution via nitrate (NO3-) leaching and emissions of N trace gases. Fertilization increases the emissions of nitrous oxide (N2O) which is 260 stronger greenhouse gas than carbon dioxide (CO2). It also enhances the emissions of nitric oxide (NO); an oxidized and very reactive form of nitrogen which can fluctuate the ozone (O3) concentration in atmosphere and cause acidification. The effects of N- fertilization on the emission of N2O and NO from agricultural soil are well known. However, the effects of N fertilization on nitrous acid (HONO) emissions are unknown. Few studies have shown that HONO is emitted from soil but they lack to interlink fertilization and HONO emission. HONO accounts for 17-34 % of hydroxyl (OH-) radical production? in the atmosphere, OH- radicals have vital role in atmospheric chemistry; they can cause photochemical smog, form O3, oxidize volatile organic compounds and also atmospheric methane (CH4). We formulated hypothesis that N fertilization will increase the HONO emissions as it does for N2O and NO. To study this, we took soil samples from agricultural soil receiving different amount of N-fertilizer (0, 250 and 450 kg ha-1) in eastern Finland. HONO emissions were measured by dynamic chamber technique connected with LOPAP (Quma Elektronik & Analytik GmbH), NO by NOx analyzer (Thermo scientific) and static chamber technique and gas chromatograph was used for N2O gas sampling and analysis. Several soil parameters were also measured to establish the relationship between the soil properties, fertilization rate and HONO emission. This study is important because eventually it will open up more questions regarding the forms of N loss from soils and impact of fertilization on atmospheric chemistry.

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

    Directory of Open Access Journals (Sweden)

    Y. H. Wang

    2012-10-01

    Full Text Available Subtropical forests in South 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 hill slope (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 in 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 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 (0.50 and 0.41 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 South China are an important, hitherto overlooked component of the anthropogenic N2O budget.

  7. Ocean N2O Emissions : Recent Global Estimates and Anthropogenically Influenced Changes

    Science.gov (United States)

    Suntharalingam, P.; Buithenuis, E.; Andrews, O.; Le Quere, C.

    2016-12-01

    Oceanic N2O is produced by microbial activity during organic matter cycling in the subsurface ocean; its production mechanisms display sensitivity to ambient oxygen level. In the oxic ocean, N2O is produced as a byproduct during the oxidation of ammonia to nitrate, mediated by ammonia oxidizing bacteria and archea. N2O is also produced and consumed in sub-oxic and anoxic waters through the action of marine denitrifiers during the multi-step reduction of nitrate to gaseous nitrogen. The oceanic N2O distribution therefore displays significant heterogeneity with background levels of 10-20 nmol/l in the well-oxygenated ocean basins, high concentrations (> 40 nmol/l) in hypoxic waters, and N2O depletion in the core of ocean oxygen minimum zones (OMZs). Oceanic N2O emissions are estimated to account for up to a third of the pre-industrial N2O fluxes to the atmosphere, however the natural cycle of ocean N2O has been perturbed in recent decades by inputs of anthropogenically derived nutrient, and by the impacts of climate change. Anthropogenic nitrogen inputs (e.g., NOx and NHy from fossil fuel combustion and agricultural fertilizer) enter the ocean via atmospheric deposition and riverine fluxes, influencing oceanic N2O production via their impact on the marine organic matter cycle. In addition, climate variations associated with surface ocean warming affect oceanic circulation and nutrient transport pathways, influencing marine productivity and the ventilation of oxygen minimum zones. Recent studies have suggested that possible expansion of oceanic OMZs in a warming climate could lead to significant changes in N2O production and fluxes from these regions. We will summarise the current state of knowledge on the ocean N2O budget and net flux to the atmosphere. Recently reported estimates have been based on (i) empirical relationships derived from ocean tracer data (e.g., involving excess N2O and Apparent Oxygen Utilization (AOU) correlations), (ii) ocean biogeochemical

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

    Science.gov (United States)

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

    2015-12-01

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

  9. 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.

  10. Effect of long-term compost and inorganic fertilizer application on background N2O and fertilizer-induced N2O emissions from an intensively cultivated soil.

    Science.gov (United States)

    Ding, Weixin; Luo, Jiafa; Li, Jie; Yu, Hongyan; Fan, Jianling; Liu, Deyan

    2013-11-01

    The influence of inorganic fertilizer and compost on background nitrous oxide (N2O) and fertilizer-induced N2O emissions were examined over a maize-wheat rotation year from June 2008 to May 2009 in a fluvo-aquic soil in Henan Province of China where a field experiment had been established in 1989 to evaluate the long-term effects of manure and fertilizer on soil organic status. The study involved five treatments: compost (OM), fertilizer NPK (nitrogen-phosphorus-potassium, NPK), half compost N plus half fertilizer N (HOM), fertilizer NK (NK), and control without any fertilizer (CK). The natural logarithms of the background N2O fluxes were significantly (P<0.05) correlated with soil temperature, but not with soil moisture, during the maize or wheat growing season. The 18-year application of compost alone and inorganic fertilizer not only significantly (P<0.05) increased soil organic carbon (SOC) by 152% and 10-43% (respectively), but also increased background N2O emissions by 106% and 48-76% (respectively) compared with the control. Total N in soils was a better indicator for predicting annual background N2O emission than SOC. The estimated emission factor (EF) of mineralized N, calculated by dividing annual N2O emission by mineralized N was 0.13-0.19%, significantly (P<0.05) lower than the EF of added N (0.30-0.39%). The annual N2O emission in the NPK, HOM and OM soils amended with 300 kg ha(-1) organic or inorganic N was 1427, 1325 and 1178 g N ha(-1), respectively. There was a significant (P<0.05) difference between the NPK and OM. The results of this study indicate that soil indigenous N was less efficiently converted into N2O compared with exogenous N. Increasing SOC by compost application, then partially increasing N supply to crops instead of adding inorganic N fertilizer, may be an effective measure to mitigate N2O emissions from arable soils in the North China plain. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Experimental Research on Heterogeneous N2O Decomposition with Ash and Biomass Gasification Gas

    Directory of Open Access Journals (Sweden)

    Wu Qin

    2011-11-01

    Full Text Available In this paper, the promoting effects of ash and biomass gas reburning on N2O decomposition were investigated based on a fluidized bed reactor, with the assessment of the influence of O2 on N2O decomposition with circulating ashes. Experimental results show that different metal oxides contained in ash play distinct roles in the process of N2O decomposition with biomass gas reburning. Compared with other components in ash, CaO is proven to be very active and has the greatest promoting impact on N2O decomposition. It is also found that O2, even in small amounts, can weaken the promoting effect of ash on N2O decomposition by using biomass gas reburning.

  12. 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.

    Process models describing nitrous oxide (N2O) production during biological nitrogen removal allow for the development of mitigation strategies of this potent greenhouse gas. N2O is an intermediate of nitrogen removal, hence its prediction is negatively affected by the uncertainty associated to its...... 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....... The results show the need for information-rich experiemental designs to assess the predicting capabilities of N2O models. This work represents a step further in understanding the N2O production and emissions associated to conventional wastewater treatment. Moreovere, it will facilitate the development...

  13. 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.

  14. Conversion of cropland to forest increases soil CH4 oxidation and abundance of CH4 oxidizing bacteria with stand age

    DEFF Research Database (Denmark)

    Bárcena, Teresa G; D'Imperio, Ludovica; Gundersen, Per

    2014-01-01

    -oxidizing bacteria (MOB) and ammonia-oxidizing bacteria (AOB) and archaea (AOA) based on quantitative PCR (qPCR) on pmoA and amoA genes. Our study showed that CH4 oxidation rates and the abundance of MOB increased simultaneously with time since afforestation, suggesting that the methanotrophic activity is reflected...... in the abundance of this functional group. The development of forest soils resulted in increased soil organic carbon and reduced bulk density, and these were the two variables that most strongly related to CH4 oxidation rates in the forest soils. For the top mineral soil layer (0–5 cm) CH4 oxidation rates did...... not differ between even aged stands from oak and larch, and were significantly smaller under Norway spruce. Compared to the other tree species Norway spruce caused a decrease in the abundance of MOB over time that could explain the decreased oxidation rates. However, the cause for the lower abundance remains...

  15. 土壤CH4产生机理及其排放的影响因素%Generation Mechanism and Impact Factors on CH4 Emission

    Institute of Scientific and Technical Information of China (English)

    孙树臣; 翟胜; 王巨媛; 贾富; 刘力; 李成帅

    2011-01-01

    CH4是引起全球变暖的温室气体之一,土壤是CH4的重要排放源和汇,土壤CH4的研究对控制CH4排放、延缓气候变暖具有重要意义.在介绍土壤CH4产生与排放机理的基础上,概述了土壤理化特性、土地利用方式、农业管理措施等对土壤CH4排放的影响,并在此基础上对土壤CH4及其他温室气体的研究进行了展望.%Methane (CH4) is one of the important greenhouse gases that lead to global climate warming. Soil is an important source and sink of CH4. Researching on CH4 is of great importance to control of CH4 emission and global warming. Effects of soil physical and chemical properties, land usepatterns and agricultural management measures on CH4 emission are reviewed and researches on the emissions of CH4 and other greenhouse gases are put forward based on the introduction in mechanism of soil CH4 generating and emitting.

  16. 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.

  17. 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

  18. Effects of nitrogen application and maize growth on N2O emission from soil

    Institute of Scientific and Technical Information of China (English)

    YANG Lanfang; CAI Zucong

    2007-01-01

    Using the pot experiment and closed static chamber-gas chromatography(GC)technique,this paper studied the effects of nitrogen application(150 and 300 mg/kg soil)and maize growth on N2O emission from soil.In maizeplanted soil,the N2O emission rate increased with increasing N application rate,its peak appeared at the seedling stage,and there was no significant correlation between N20 emission rate and air temperature.Contrarily,in exposed soil,the peak of N20 emission rate occurred at the later stages of the experiment,and there was a significant exponential correlation between soil N2O emission rate and air temperature,in which Q10(the value of soil N2O emission rate responding to temperature)was 4.4 and 3.2 in high and low N applications.The total amount of N2O emission increased remarkably with increased N application rate in both planted and un-planted soils.N2O emission inventory from exposed and maizeplanted soils in high N application was 2.5 and 1.6 times as high as that in low N application,respectively.In the same N application rate,N2O emission inventory in high and low N application from exposed soil was 12 and 7.5 times as high as that from maize-planted soil,respectively.As compared with exposed soil,maize growth reduced N2O emission by 92% and 87%,respectively,at high and low N application rates.In summary,maize growth and nitrogen application not only affected the seasonal variation and magnitude of N2O emission from soil,but also altered the relationship between air temperature and soil N2O emission.

  19. Microhabitat Effects on N2O Emissions from Floodplain Soils under Controlled Conditions

    Science.gov (United States)

    Ley, Martin; Lehmann, Moritz; Niklaus, Pascal; Frey, Beat; Kuhn, Thomas; Luster, Jörg

    2015-04-01

    Semi-terrestrial soils such as floodplain soils are considered to be potential hotspots of nitrous oxide (N2O) emissions. The quantitative assessment of N2O release from these hot spots under field conditions, and of the microbial pathways that underlie net N2O production (ammonium oxidation, nitrifier-denitrification, and denitrification) is challenging in the environment because of the high spatial and temporal variability. The production and consumption of N2O appears to be linked to the presence or absence of micro-niches, providing specific conditions that may be favorable to either of the microbial pathways that produce or consume N2O. The availability of oxygen, reactive organic carbon, and dissolved nitrogen substrates likely play key roles with regards to the net production of N2O. Previous field studies demonstrated, for example, that flooding can trigger "hot moments" of enhanced N2O emission through a close coupling of niches with high and low oxygen availabilities. Such microhabitat effects likely depend on soil aggregate formation, plant soil interactions in the rhizosphere and the degradation of organic matter accumulations. In order to assess how these factors can modulate N2O production and consumption under simulated flooding/drying conditions, we have set up a mesocosm experiment with model soils comprising various mixtures of N-rich floodplain soil aggregates (4000 - 250 µm representing large aggregates, or preference. Changes in soil microbial communities, potentially controlling the balance between N2O production and consumption under different microhabitat conditions will be assessed using high-throughput DNA sequencing and q-PCR of key functional genes. Our study helps to increase our limited understanding of how microhabitats affect the occurrence of high N2O emissions from floodplain soils.

  20. Isotopomeric characterization of N2O produced, consumed, and emitted by automobiles.

    Science.gov (United States)

    Toyoda, Sakae; Yamamoto, Sei-ichiro; Arai, Shinji; Nara, Hideki; Yoshida, Naohiro; Kashiwakura, Kiriko; Akiyama, Ken-ichi

    2008-01-01

    Fossil fuel combustion is the second largest anthropogenic source of nitrous oxide (N2O) after agriculture. The estimated global N2O flux from combustion sources, as well as from other sources, still has a large uncertainty. Herein, we characterize automobile sources using N2O isotopomer ratios (nitrogen and oxygen isotope ratios and intramolecular site preference of 15N, SP) to assess their contributions to total global sources and to deconvolute complex production/consumption processes during combustion and subsequent catalytic treatments of exhaust. Car exhaust gases were sampled under running and idling state, and N2O isotopomer ratios were measured by mass spectrometry. The N2O directly emitted from an engine of a vehicle running at constant velocity had almost constant isotopomer ratios (delta15Nbulk = -28.7 +/- 1.2 per thousand, delta18O = 28.6 +/- 3.3 per thousand, and SP = 4.2 +/- 0.8 per thousand) irrespective of the velocity. After passing through catalytic converters, the isotopomer ratios showed an increase which varied with the temperature and the aging of the catalysts. The increase suggests that both production and consumption of N2O occur on the catalyst and that their rates can be comparable. It was noticed that in the idling state, the N2O emitted from a brand new car has higher isotopomer ratios than that from used cars, which indicate that technical improvements in catalytic converters can reduce the N2O from mobile combustion sources. On average, the isotopomeric signatures of N2O finally emitted from automobiles are not sensitive to running/idling states or to aging of the catalysts. Characteristic average isotopomer ratios of N2O from automobile sources are estimated at -4.9 +/- 8.2 per thousand, 43.5 +/- 13.9 per thousand, and 12.2 +/- 9.1 per thousand for delta15Nbulk, delta18O, and SP, respectively.

  1. Real-time analysis of δ13C- and δD-CH4 by high precision laser spectroscopy

    Science.gov (United States)

    Eyer, Simon; Emmenegger, Lukas; Tuzson, Béla; Fischer, Hubertus; Mohn, Joachim

    2014-05-01

    Methane (CH4) is the most important non-CO2 greenhouse gas (GHG) contributing 18% to total radiative forcing. Anthropogenic sources (e.g. ruminants, landfills) contribute 60% to total emissions and led to an increase in its atmospheric mixing ratio from 700 ppb in pre-industrial times to 1819 ± 1 ppb in 2012 [1]. Analysis of the most abundant methane isotopologues 12CH4, 13CH4 and 12CH3D can be used to disentangle the various source/sink processes [2] and to develop target oriented reduction strategies. High precision isotopic analysis of CH4 can be accomplished by isotope-ratio mass-spectrometry (IRMS) [2] and more recently by mid-infrared laser-based spectroscopic techniques. For high precision measurements in ambient air, however, both techniques rely on preconcentration of the target gas [3]. In an on-going project, we developed a fully-automated, field-deployable CH4 preconcentration unit coupled to a dual quantum cascade laser absorption spectrometer (QCLAS) for real-time analysis of CH4 isotopologues. The core part of the rack-mounted (19 inch) device is a highly-efficient adsorbent trap attached to a motorized linear drive system and enclosed in a vacuum chamber. Thereby, the adsorbent trap can be decoupled from the Stirling cooler during desorption for fast desorption and optimal heat management. A wide variety of adsorbents, including: HayeSep D, molecular sieves as well as the novel metal-organic frameworks and carbon nanotubes were characterized regarding their surface area, isosteric enthalpy of adsorption and selectivity for methane over nitrogen. The most promising candidates were tested on the preconcentration device and a preconcentration by a factor > 500 was obtained. Furthermore analytical interferants (e.g. N2O, CO2) are separated by step-wise desorption of trace gases. A QCL absorption spectrometer previously described by Tuzson et al. (2010) for CH4 flux measurements was modified to obtain a platform for high precision and simultaneous

  2. Renewable energy based catalytic CH4 conversion to fuels

    NARCIS (Netherlands)

    Baltrusaitis, Jonas; Jansen, I.; Schuttlefield, J.D.S.

    2014-01-01

    Natural gas is envisioned as a primary source of hydrocarbons in the foreseeable future. With the abundance of shale gas, the main concerns have shifted from the limited hydrocarbon availability to the sustainable methods of CH4 conversion to fuels. This is necessitated by high costs of natural gas

  3. Inverse modeling of European CH4 emissions 2001–2006

    NARCIS (Netherlands)

    Bergamaschi, P.; Krol, M.C.; Meirink, J.F.; Dentener, F.; Segers, A.; Aardenne, van J.A.; Monni, S.; Vermeulen, A.T.

    2010-01-01

    European CH4 emissions are estimated for the period 2001–2006 using a fourdimensional variational (4DVAR) inverse modeling system, based on the atmospheric zoom model TM5. Continuous observations are used from various European monitoring stations, complemented by European and global flask samples fr

  4. Infrared absorption spectroscopy of gas-phase N2O-HX (X=F, Cl, Br) weakly bonded complexes utilizing the N2O nu(3) chromophore

    Science.gov (United States)

    Zeng, Y. P.; Sharpe, S. W.; Reifschneider, D.; Wittig, C.; Beaudet, R. A.

    1990-07-01

    Pulsed, slotted nozzle expansions and tunable diode lasers were employed in the present recording of the rovibrational absorption spectra of weakly-bonded complexes of N2O with HF, DF, HCl, and HBr in the nu(3) region of N2O; the fast-scan technique used yielded 4000 resolution elements with a single opening of the nozzle. Of the two known NH- and OH-bonded isomers of N2O-HF, only linear ONN-HF was detected. High resolution spectra of NNO-HCl and NNO-HBr are presented. The qualitative changes observed in NNO-HX geometries and force fields are attributed to the competing effects of hydrogen-bonding and dispersion forces.

  5. Photoinitiated H- and D-atom reactions with N2O in the gas phase and in N2O-HI and N2O-DI complexes

    Science.gov (United States)

    Böhmer, E.; Shin, S. K.; Chen, Y.; Wittig, C.

    1992-08-01

    Reactions of H atoms with N2O have two product channels yielding NH+NO and OH+N2. Both channels were observed via NH A 3Π←X 3∑ and OH A 2∑←X 2Π laser-induced fluorescence spectra. Photoinitiated reactions with N2O-HI complexes yield a much lower [NH]/[OH] ratio than under the corresponding bulk conditions at the same photolysis wavelength. For hot D-atom reactions with N2O, this effect is somewhat more pronounced. These results can be interpreted in terms of entrance channel geometric specificity, namely, biasing hydrogen attack toward the oxygen. Another striking observation is that the OH and OD rotational level distributions (RLD) obtained under bulk conditions differ markedly from those obtained under complexed conditions, while the NH as well as the ND RLD are similar for the two environments. In addition, OH Doppler profiles change considerably in going from bulk to complexed conditions, while such an effect is not observed for NH. The changes observed with the OH RLD are most likely due to OH-halogen interactions and/or entrance channel specificity. Under bulk conditions, the Doppler shift measurements indicate a large amount of N2 internal excitation (i.e., ˜25 000 cm-1) for the OH (v=0) levels monitored. This is consistent with a reaction mechanism involving an HNNO° intermediate. The hot hydrogen atom first attaches to the terminal nitrogen of N2O and forms an excited HNNO° intermediate having a relatively elongated N-N bond compared with N2O. Then the H atom migrates from nitrogen to oxygen and exits to the N2+OH product channel, leaving N2 vibrationally excited. A simple Franck-Condon model can reconcile quantitatively the large amount of N2 vibrational excitation.

  6. Response of N2O Emissions of Farmland Ecosystem on Temperature Rising

    Institute of Scientific and Technical Information of China (English)

    Liusong LIU; Jiancheng SHI

    2012-01-01

    [Objective] The aim was to study on response of N2O emissions of farm- land ecosystem on temperature rising. [Methed] In farmland ecosystem in Huaibei City in Anhui Province, N2O emission by twelve varieties of crop on temperature was researched with DeNitrification-DeComposition (NDC). [Result] Response of dry- land crop on temperature rising can be divided into three categories, as follows: The first category, N2O emission of crop changed little during the temperature increasing, for example, from 0 to 3 %;, the emissions by potatoes, cotton, maize and rapeseed increased little and decreased little when temperature changed from 1.5 to 3 ℃. Crops of the second category declined with temperature increasing in N2O emission, for example, N2O emission decreased by 8.1% with temperature increasing from 0 to 3 ℃, including sugar cane, tobacco, wheat, soybean and pea. In third category, N2O emission of crop grew with temperature increasing, for example, the emission of rice, vegetables and fruit trees increased by 22.8% when the temperature grew from 0 to 3 ℃. [Conclusion] The research indicated that N2O emission in ecosystem of drv farmland increased little with temoerature risina.

  7. Spatial variability and hotspots of soil N2O fluxes from intensively grazed grassland

    Science.gov (United States)

    Cowan, N. J.; Norman, P.; Famulari, D.; Levy, P. E.; Reay, D. S.; Skiba, U. M.

    2015-03-01

    One hundred N2O flux measurements were made from an area of intensively managed grazed grassland in central Scotland using a high-resolution dynamic chamber method. The field contained a variety of features from which N2O fluxes were measured including a manure heap, patches of decaying grass silage, and areas of increased sheep activity. Individual fluxes varied significantly across the field varying from 2 to 79 000 μg N2O-N m-2 h-1. Soil samples were collected at 55 locations to investigate relationships between soil properties and N2O flux. Fluxes of N2O correlated strongly with soil NO3- concentrations. Distribution of NO3- and the high spatial variability of N2O flux across the field are shown to be linked to the distribution of waste from grazing animals and the resultant reactive nitrogen compounds in the soil which are made available for microbiological processes. Features within the field such as shaded areas and manure heaps contained significantly higher available nitrogen than the rest of the field. Although these features only represented 1.1% of the area of the field, they contributed to over 55% of the total estimated daily N2O flux.

  8. Effects of NH3 on N2O Formation and Destruction in Fluidized Bed Coal Combustion

    Institute of Scientific and Technical Information of China (English)

    JianWeiYuan; BoFeng; 等

    1994-01-01

    The NH3 oxidation and reduction process are experimentally and kinetically studied in this paper,It is found that NH3 has contributions not only to N2O formation,but also to N2O destruction in certain conditions.The main product of homogeneous NH3 oxidation is found to be NO rather than N2O,but some bed materials and suplhur sorbents have catalytic contributions to N2O formation from NH3 oxidation.In reduction atmosphere,NH3 can promote the KC destruction.It is deduced that the ammonia injection into fluidized bed coal combustion flue gas can decrease both NOx and N2O emissions.The ammonia injection process is kinetically simulated in this study,and the reduction.rates of NOx and N2O are found to depend on temperature,O2 concentration,initial NOx and N2O concentrations,and amount of injected ammonia.

  9. Direct N2O5 reactivity measurements at a polluted coastal site

    Directory of Open Access Journals (Sweden)

    K. A. Prather

    2011-12-01

    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 2O5 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".

  10. 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.

  11. N2O Emission from Paddy Field under Different Rice Planting Modes

    Institute of Scientific and Technical Information of China (English)

    WANG Yuying; ZHU Bo; WANG Yanqiang; GAO Meirong; MA Xiumei

    2006-01-01

    Measurements of N2O emissions from conventional rice cultivation (CRC), CRC with straw mulching, system of rice intensification (SRI) and SRI with plastic film mulching were conducted through static chamber/gas-chromatography techniques. The results show that daily fluctuation of N2O emissions in jointing stage are much higher than in others. A type peak of N2O seasonal emission presented between jointing and bearing stages companying with high daily average temperature and low precipitation. Biomass and leaf stomatal conductance were observed. Total quantities of N2O emission were budgeted. The results showed that after jointing stage the average N2O emission flux of SRI with plastic film mulching increased significantly than CRC with straw mulching and SRI, the leaf stomatal conductance of those showed the same trend (p<0.05). Yield and total quantity of N2O emission in CRC with straw mulching enhanced 13.7% and 10.7% compared with those of CRC, respectively. The total quantity of N2O emissions reduced 3.6% in SRI with plastic film mulching compared with CRC, however, the yield increase of that was not significant.

  12. [Effects of controlled release fertilizers on N2O emission from paddy field].

    Science.gov (United States)

    Li, Fangmin; Fan, Xiaolin; Liu, Fang; Wang, Qiang

    2004-11-01

    With close chamber method, this paper studied the effects of controlled release fertilizer (CRF), non-coated compound fertilizer (Com) and conventional urea (CK) on N2O emission from paddy field. The results showed that within 10 days after transplanting, the ammonium and nitrate concentrations in the surface water of the plot treated with CRF were significantly different from those treated with Com. The partial coefficient between N2O emission rates and corresponding nitrate concentrations in the water was significantly high (r = 0.6834). Compared with Com, CRF was able to reduce N2O emission from the paddy field. Within 100 days after basal application, the N2O emission rate of treatment CRF was only 13.45%-21.26% of Corn and 71.17%-112.47% of CK. The N2O emission of Com was mainly concentrated in 1-25 d after basal fertilization and mid-aeration period, but that of CRF was remarkably lower during same period, while the peak of N2O emission of CK was postponed and reduced. It was concluded that both one-time fertilization of CRF and several-time fertilizations of conventional urea were able to reduce N2O emission from the paddy field.

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

    Directory of Open Access Journals (Sweden)

    P. Dörsch

    2012-02-01

    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 replacement as biogas residue to a subsequent barley crop. Grass-clover ley had small but significantly higher N2O emissions as compared with a non-fertilized 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 (110 kg N ha−1 before sowing did not increase emissions neither when applied to previous ley plots nor when applied to previously unfertilized 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. 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 fertilization in 2010 (47 g N2O-N kg−1 N yield in barley grain.

  14. Evaluating N2O5 heterogeneous hydrolysis parameterizations for CalNex 2010

    Science.gov (United States)

    Chang, Wayne L.; Brown, Steven S.; Stutz, Jochen; Middlebrook, Ann M.; Bahreini, Roya; Wagner, Nicholas L.; Dubé, William P.; Pollack, Ilana B.; Ryerson, Thomas B.; Riemer, Nicole

    2016-05-01

    Nighttime chemistry in the troposphere is closely tied to the dinitrogen pentoxide (N2O5) budget, but high uncertainties remain regarding the model representation of the heterogeneous hydrolysis of N2O5 on aerosol particles. In this study we used the community model WRF-Chem to simulate a 3-day period during the California Nexus (CalNex) Campaign in 2010. We extended WRF-Chem to include the heterogeneous hydrolysis of N2O5 and contrasted the impact of different published parameterizations of N2O5 heterogeneous hydrolysis on the spatial distribution of uptake coefficients and the resulting N2O5 concentrations. For all the cases, modeled N2O5 uptake coefficients showed strong spatial variability, with higher values in the nocturnal boundary layer compared to the residual layer, especially in environments with high relative humidities, such as over the ocean and along the coast. The best agreement of modeled and observed uptake coefficients was obtained using the parameterization by Davis et al. (2008) combined with the treatment of organic coating by Riemer et al. (2009). For this case the temporal evolution of lower boundary layer N2O5 mixing ratios was reproduced well, and the predictions of surface mixing ratios of ozone and NOx were improved. However, the model still overpredicted the uptake coefficients in the residual layer and consequently underpredicted N2O5 concentrations in the residual layer. This study also highlights that environments with low relative humidities pose a challenge for aerosol thermodynamic models in calculating aerosol water uptake, and this impacts N2O5 heterogeneous hydrolysis parameterizations.

  15. Biochar increases soil N2O emissions produced by nitrification-mediated pathways

    Directory of Open Access Journals (Sweden)

    María eSánchez-García

    2014-07-01

    Full Text Available In spite of the numerous studies reporting a decrease in soil nitrous oxide (N2O emissions after biochar amendment, there is still a lack of understanding of the processes involved. Hence the subject remains controversial, with a number of studies showing no changes or even an increase in N2O emissions after biochar soil application. Unraveling the exact causes of these changes, and in which circumstances biochar decreases or increases emissions, is vital to developing and applying successful mitigation strategies. With this objective, we studied two soils (Haplic Phaeozem (HP and Haplic Calcisol (HC, which showed opposed responses to biochar amendment. Under the same experimental conditions, the addition of biochar to soil HP decreased N2O emissions by 76%; whereas it increased emissions by 54% in soil HC. We combined microcosm experiments adding different nitrogen fertilizers, stable isotope techniques and the use of a nitrification inhibitor (dicyciandiamide with the aim of improving our understanding of the mechanisms involved in the formation of N2O in these two soils. Evidence suggests that denitrification is the main pathway leading to N2O emissions in soil HP, and ammonia oxidation and nitrifier-denitrification being the major processes generating N2O in soil HC. Biochar systematically stimulated nitrification in soil HC, which was probably the cause of the increased N2O emissions. Here we demonstrate that the effectiveness of using biochar for reducing N2O emissions from a particular soil is linked to its dominant N2O formation pathway.

  16. 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.

  17. 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, Psoil 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.

  18. Modeling N2O Reduction and Decomposition in a Circulating Fluidized bed Boiler

    DEFF Research Database (Denmark)

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

    1996-01-01

    in the combustion chamber and the cyclone was calculated taking three mechanisms into account: Reduction by char, catalytic decomposition over bed material and thermal decomposition. The calculated destruction rate was in good agreement with the measured destruction of N2O injected at different levels in the boiler...... decomposition over bed material, and homogeneous thermal decomposition was negligible. However, at higher levels in the combustor the solids concentration is lower: at the top 60% of the N2O destruction was due to thermal decomposition and in the cyclone heterogeneous destruction of N2O was insignificant...

  19. Dolomite application to acidic soils: a promising option for mitigating N2O emissions.

    Science.gov (United States)

    Shaaban, Muhammad; Peng, Qi-An; Hu, Ronggui; Wu, Yupeng; Lin, Shan; Zhao, Jinsong

    2015-12-01

    Soil acidification is one of the main problems to crop productivity as well as a potent source of atmospheric nitrous oxide (N2O). Liming practice is usually performed for the amelioration of acidic soils, but the effects of dolomite application on N2O emissions from acidic soils are still not well understood. Therefore, a laboratory study was conducted to examine N2O emissions from an acidic soil following application of dolomite. Dolomite was applied to acidic soil in a factorial design under different levels of moisture and nitrogen (N) fertilizer. Treatments were as follows: dolomite was applied as 0, 1, and 2 g kg(-1) soil (named as CK, L, and H, respectively) under two levels of moisture [i.e., 55 and 90 % water-filled pore space (WFPS)]. All treatments of dolomite and moisture were further amended with 0 and 200 mg N kg(-1) soil as (NH4)2SO4. Soil properties such as soil pH, mineral N (NH4 (+)-N and NO3 (-)-N), microbial biomass carbon (MBC), dissolved organic carbon (DOC), and soil N2O emissions were analyzed throughout the study period. Application of N fertilizer rapidly increased soil N2O emissions and peaked at 0.59 μg N2O-N kg(-1) h(-1) under 90 % WFPS without dolomite application. The highest cumulative N2O flux was 246.32 μg N2O-N kg(-1) under 90 % WFPS without dolomite addition in fertilized soil. Addition of dolomite significantly (p ≤ 0.01) mitigated N2O emissions as soil pH increased, and H treatment was more effective for mitigating N2O emissions as compared to L treatment. The H treatment decreased the cumulative N2O emissions by up to 73 and 67 % under 55 and 90 % WFPS, respectively, in fertilized soil, and 60 and 68 % under 55 and 90 % WFPS, respectively, in unfertilized soil when compared to those without dolomite addition. Results demonstrated that application of dolomite to acidic soils is a promising option for mitigating N2O emissions.

  20. Direct N2O Fluxes from Agroecosystems in Cold Climates: Importance of Soil Freeze-Thaw

    Science.gov (United States)

    Congreves, K. A.; Wagner-Riddle, C.; Abalos, D.; Ambadan, J. T.; Brown, S. E.; Tenuta, M.; Gao, X.; Amiro, B. D.; Berg, A. A.

    2016-12-01

    To develop effective climate change mitigation strategies and reduce N2O emissions, the global contribution of freeze-thaw cycles from croplands must be characterized; we present the first study to do so. Long-term N2O flux datasets from micrometeorological approaches were compiled from two Canadian sites (Elora ON & Glenlea MB). Measurements encompassed a total of 21-yr on 16-ha of land producing annual field crops, yielding an unprecedented record of N2O fluxes (42118 half-hourly values) at sites subjected to freeze-thaw cycles from Nov-Apr. At Elora (the warmer site) N2O flux events were associated with thaw cycles throughout Nov-Apr and the main thaw event took place between mid/end of April when air temperatures rose above 0°C and snow melted. The continental site (Glenlea) did not have significant N2O flux events during the prolonged freeze period, but had considerably higher emissions over the thaw period when soil temperature and liquid water content increased more slowly than Elora. Based on cumulative N2O emissions from both sites (Nov-Apr), emissions were closely related to freezing degree days (FDD). An exponential-to-plateau model significantly fit (p<0.0001, r= 0.72) the relationship between N2O emissions and FDD, characterizing larger N2O emissions as FDD increased (y=1.95 (1-exp-0.00852x), y=cumulative N2O-N kg ha-1 and x=FDD). To estimate the global contribution of N2O emissions from seasonally frozen croplands in the northern hemisphere, we applied the algorithm to a global map of FDD derived from three reanalysis products (ERA-Interim, MERRA-Land, GLDAS-NOAH) combined with MODIS land fraction data for croplands. Average global freeze-thaw induced N2O emissions for croplands was estimated at 1.07 Tg N, though it may range from 0.79 - 1.35 Tg N due to model error and variation. This global contribution of N2O from seasonally frozen cropland soils may be responsible for previously observed discrepancies between top-down and bottom-up approaches.

  1. A toy model for estimating N2O emissions from natural soils

    Science.gov (United States)

    Fung, Inez

    1992-01-01

    A model of N2O emissions from natural soils, whose ultimate objective is to evaluate what contribution natural ecosystems make to the global N2O budget and how the contribution would change with global change, is presented. Topics covered include carbon and nitrogen available in the soil, delivery of nitrifiable N, soil water and oxygen status, soil water budget model, effects of drainage, nitrification and denitrification potentials, soil fertility, N2O production, and a model evaluation. A major implication of the toy model is that the tropics account for more than 80 percent of global emission.

  2. A New High-Resolution N2O Emission Inventory for China in 2008

    Science.gov (United States)

    Shang, Z.; Zhou, F.; Ciais, P.; Tao, S.; Piao, S.; Raymond, P. A.; He, C.; Li, B.; Wang, R.; Wang, X.; Peng, S.; Zeng, Z.; Chen, H.; Ying, N.; Hou, X.; Xu, P.

    2014-12-01

    The amount and geographic distribution of N2O emissions over China remain largely uncertain. Most of existing emission inventories use uniform emission factors (EFs) and the associated parameters and apply spatial proxies to downscale national or provincial data, resulting in the introduction of spatial bias. In this study, county-level and 0.1° × 0.1° gridded anthropogenic N2O emission inventories for China (PKU-N2O) in 2008 are developed based on high-resolution activity data and regional EFs and parameters. These new estimates are compared with estimates from EDGAR v4.2, GAINS-China, National Development and Reform Commission of China (NDRC), and with two sensitivity tests: one that uses high-resolution activity data but the default IPCC methodology (S1) and the other that uses regional EFs and parameters but starts from coarser-resolution activity data. The total N2O emissions are 2150 GgN2O/yr (interquartile range from 1174 to 2787 GgN2O/yr). Agriculture contributes 64% of the total, followed by energy (17%), indirect emissions (12%), wastes (5%), industry (2.8%), and wildfires (0.2%). Our national emission total is 17% greater than that of the EDGAR v4.2 global product sampled over China and is also greater than the GAINS-China, NDRC, and S1 estimates by 10%, 50%, and 17%, respectively. We also found that using uniform EFs and parameters or starting from national/provincial data causes systematic spatial biases compared to PKU-N2O. In addition, the considerable differences between the relative contributions of the six sectors across the six Agro-Climate Zones primarily reflect the different distributions of industrial activities and land use. Eastern China (8.7% area of China) is the largest contributor of N2O emissions and accounts for nearly 25% of the total. Spatial analysis also shows nonlinear relationships between N2O emission intensities and urbanization. Per-capita and per-GDP N2O emissions increase gradually with an increase in the urban

  3. Chlorine activation by N2O5: simultaneous, in situ detection of ClNO2 and N2O5 by chemical ionization mass spectrometry

    Directory of Open Access Journals (Sweden)

    J. A. Thornton

    2009-05-01

    Full Text Available We report a new method for the simultaneous in situ detection of nitryl chloride (ClNO2 and dinitrogen pentoxide (N2O5 using chemical ionization mass spectrometry (CIMS. The technique relies on the formation and detection of iodide ion-molecule clusters, I(ClNO2− and I(N2O5−. The novel N2O5 detection scheme is direct. It does not suffer from high and variable chemical interferences, which are associated with the typical method of nitrate anion detection. We address the role of water vapor, CDC electric field strength, and instrument zero determinations, which influence the overall sensitivity and detection limit of this method. For both species, the method demonstrates high sensitivity (>1 Hz/pptv, precision (~10% for 100 pptv in 1 s, and accuracy (~20%, the latter ultimately determined by the nitrogen dioxide (NO2 cylinder calibration standard and characterization of inlet effects. For the typically low background signals (S/N ratios of 2 for 1 pptv in 60 s averages, but uncertainty associated with the instrumental zero currently leads to an ultimate detection limit of ~5 pptv for both species. We validate our approach for the simultaneous in situ measurement of ClNO2 and N2O5 while on board the R/V Knorr as part of the ICEALOT 2008 Field Campaign.

  4. On the use of satellite-derived CH4 : CO2 columns in a joint inversion of CH4 and CO2 fluxes

    NARCIS (Netherlands)

    Pandey, S.

    2015-01-01

    We present a method for assimilating total column CH4 : CO2 ratio measurements from satellites for inverse modeling of CH4 and CO2 fluxes using the variational approach. Unlike conventional approaches, in which retrieved CH4 : CO2 are multiplied by model-derived total column CO2 and only the resulti

  5. On the use of satellite-derived CH4 : CO2 columns in a joint inversion of CH4 and CO2 fluxes

    NARCIS (Netherlands)

    Pandey, S.

    2015-01-01

    We present a method for assimilating total column CH4 : CO2 ratio measurements from satellites for inverse modeling of CH4 and CO2 fluxes using the variational approach. Unlike conventional approaches, in which retrieved CH4 : CO2 are multiplied by model-derived total column CO2 and only the resulti

  6. 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...

  7. Crop residues as driver for N2O emissions from a sandy loam soil

    DEFF Research Database (Denmark)

    Pugesgaard, Siri; Petersen, Søren O.; Chirinda, Ngonidzashe

    2017-01-01

    Nitrogen (N) cycling within agriculture constitutes a source of direct and indirect emissions of the potent greenhouse gas nitrous oxide (N2O). We analysed relationships between N2O emissions and C and N balances of four arable cropping systems under conventional or organic management within a long......-term experiment on a loamy sand soil at Foulum in Denmark. All cropping systems included winter wheat, a leguminous crop (faba bean or grass-clover), potato and spring barley grown in different 4-crop rotations varying in strategies for N supply (fertilizer/manure type and rate, use of catch crops and green...... manure). Crops in both organic and conventional systems received N at rates below the optimum for crop production. Soil N2O emissions were monitored in 2008–2009 in six selected crops which could be combined with data from other monitoring programs to calculate N2O emission factors for each of the 16...

  8. 40 CFR 1065.375 - Interference verification for N2O analyzers.

    Science.gov (United States)

    2010-07-01

    ... certain analyzers by causing a response similar to N2O. If the analyzer uses compensation algorithms that... other measurements to test the compensation algorithms during the analyzer interference verification....

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

    Science.gov (United States)

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

    2017-01-01

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

  11. N2O fluxes from the littoral zone of a Chinese reservoir

    National Research Council Canada - National Science Library

    M Yang; X M Geng; J Grace; Y F Jia; Y Z Liu; S W Jiao; L L Shi; C Lu; Y Zhou; G C Lei

    2015-01-01

    .... We report a case study that focuses on the littoral zone of a major Chinese reservoir, where we established measurements of N2O fluxes using the static chamber technique at five different water levels...

  12. 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...

  13. 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

  14. Dissociation of CH4 on Ni(111) and Ru(0001)

    DEFF Research Database (Denmark)

    Egeberg, Rasmus; Ullmann, S.; Alstrup, I.;

    2002-01-01

    the steps were passivated with Au. On Ni(111) sputtering the surface at 500 K with no subsequent annealing increased the initial sticking but at higher coverages this effect vanished. We interpret these results as due to the steps on both surfaces being blocked by carbon species leaving them inaccessible...... to impinging CH4 molecules. We conclude that in these types of experiments steps play a minor role for CH4 dissociation on Ru(0 0 0 1) and Ni(l 1 1). In a temperature programmed oxidation reaction we observe that carbon from the steps of Ru(0 0 0 1) leaves the surface at lower temperatures than carbon from...... the terraces, Finally we have observed a large promotion of the sticking probability of CH4 on Ru(0 0 0 1) by increasing the surface temperature at a fixed gas temperature thus lending support to a mechanism where the dissociation of methane takes place over Ru atoms displaced normal to the surface....

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

    Science.gov (United States)

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

    2012-12-01

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

  16. Denitrification Losses and N2O Emissions from Nitrogen Fertilizer Applied to a Vegetable Field

    Institute of Scientific and Technical Information of China (English)

    CAO Bing; He Fa-Yun; Xu Qiu-Ming; Yin Bin; CAI Gui-Xin

    2006-01-01

    A field experiment was conducted on Chinese cabbage (Brassica campestris L. ssp. pekinensis (Lour.) Olsson) in a Nanjing suburb in 2003. The experiment included 4 treatments in a randomized complete block design with 3 replicates: zero chemical fertilizer N (CK); urea at rates of 300 kg N ha-1 (U300) and 600 kg N ha-1 (U600), both as basal and two topdressings; and polymer-coated urea at a rate of 180 kg N ha-1 (PCU180) as a basal application. The acetylene inhibition technique was used to measure denitrification (N2 + N2O) from intact soil cores and N2O emissions in the absence of acetylene. Results showed that compared to CK total denitrification losses were significantly greater (P ≤ 0.05) in the PCU180, U300, and U600 treatments, while N2O emissions in the U300 and U600 treatments were significantly higher (P ≤ 0.05) than CK. In the U300 and U600 treatments peaks of denitrification and N2O emission were usually observed after N application. In the polymer-coated urea treatment (PCU180) during the period 20 to 40 days after transplanting, higher denitrification rates and N2O fluxes occurred. Compared with urea, polymer-coated urea did not show any effect on reducing denitrification losses and N2O emissions in terms of percentage of applied N. As temperature gradually decreased from transplanting to harvest, denitrification rates and N2O emissions tended to decrease. A significant (P ≤ 0.01) positive correlation occurred between denitrification (r = 0.872) or N2O emission (r = 0.781) flux densities and soil temperature in the CK treatment with a stable nitrate content during the whole growing season.

  17. Role of Organic Coatings in Regulating N2O5 Reactive Uptake to Sea Spray Aerosol.

    Science.gov (United States)

    Ryder, Olivia S; Campbell, Nicole R; Morris, Holly; Forestieri, Sara; Ruppel, Matthew J; Cappa, Christopher; Tivanski, Alexei; Prather, Kimberly; Bertram, Timothy H

    2015-12-03

    Previous laboratory measurements and field observations have suggested that the reactive uptake of N2O5 to sea spray aerosol particles is a complex function of particle chemical composition and phase, where surface active organics can suppress the reactive uptake by up to a factor of 60. To date, there are no direct studies of the reactive uptake of N2O5 to nascent sea spray aerosol that permit assessment of the role that organic molecules present in sea spray aerosol (SSA) may play in suppressing or enhancing N2O5 uptake kinetics. In this study, SSA was generated from ambient seawater and artificial seawater matrices using a Marine Aerosol Reference Tank (MART), capable of producing nascent SSA representative of ambient conditions. The reactive uptake coefficient of N2O5 (γ(N2O5)) on nascent SSA was determined using an entrained aerosol flow reactor coupled to a chemical ionization mass spectrometer for measurement of surface area dependent heterogeneous loss rates. Population averaged measurements of γ(N2O5) for SSA generated from salt water sequentially doped with representative organic molecular mimics, or from ambient seawater, do not deviate statistically from that observed for sodium chloride (γ(N2O5)NaCl = 0.01-0.03) for relative humidity (RH) ranging between 50 and 65%. The results are consistent with measurements made under clean marine conditions at the Scripps Institution of Oceanography Pier and those conducted on nascent SSA generated in the marine aerosol reference tank. The results presented here suggest that organic films present on nascent SSA (at RH greater than 50%) likely do not significantly limit N2O5 reactive uptake.

  18. Wetlands and Agriculture in Africa: Major Sources of N2O?

    Science.gov (United States)

    Gettel, G. M.

    2015-12-01

    Papyrus wetlands in East Africa are rapidly being converted to agricultural production in an effort to increase food security. This conversion is often seasonal, with wetlands being used for grazing and crop production of maize, sugarcane, and rice during dry seasons, and flooding occurring during wet seasons. An important question with respect to greenhouse gas production is whether wetland conversion to agriculture increases N2O fluxes. This trend has been shown in temperate regions where increased N2O fluxes are positively related to low soil C:N ratios, especially when soil moisture content remains high. In order to examine whether denitrification contributes to N2O flux, we measured potential denitrification rates (PDR by acetylene block method) in intact papyrus wetlands and agricultural converted wetlands in Kenya, Tanzania, Uganda, and Rwanda, and also performed multivariate analysis to relate soil characteristics to PDR. Agricultural land-cover types included maize, sugarcane, rice, and grazing. Results showed that intact wetlands are potentially important sources of N2O, as PDR in papyrus vegetation were consistently the highest (price fields (2.3 - 303 μg N2O g DW-1 hour-1), and intermediate in maize and sugarcane (6.5 - 75 μmg N2O g DW-1 hour-1 and 5 - 30 μg N2O g DW-1 hour-1 respectively). PDR across all sites was inversely related to soil C:N ratio, with nitrate consistently limiting PDR in the wetland sites while soil carbon limited PDR in agricultural sites. This is seemingly in contrast with other findings that show that lower C:N ratios result in high N2O fluxes from drained wetland sites. However, flux measurements along with more realistic process-based measurements of denitrification are urgently needed to more fully understand the effect of agricultural conversion of wetlands in East Africa.

  19. [Effects of salinity on N2O production during nitrification using aerobic granular sludge].

    Science.gov (United States)

    Wang, Shan-Shan; iang, Hong; Gao, Da-Wen

    2014-11-01

    An aerobic SBR biological wastewater treatment system was adopted to measure the N2O production and nitrogen removal using aerobic granular sludge nitrification process under 0, 5, 10 g x L(-1) salinity conditions. The results showed that the N2O production increased with the increase of salinity concentration. At three salinity levels (0, 5, 10 g x L(-1)), the dissolved N2O production was 1.21, 8.99, 24.81 mg x m(-3), respectively, and the released N2O was 0.95, 3.46, 16.45 mg x m(-3), respectively. The N2O release rates at the 5 g x L(-1) and 10 g x L(-1) salinity levels were 3.6 and 17.4 times as high as that at the 0 g x L(-1) salinity level. Under various salinity conditions both the dissolved and releasing state N2O production first increased and then decreased, and the dissolved N2O production was greater than that in the releasing state. In addition, when the salinity was low (less than 5 g x L(-1)), the NH4(+)-N removal rate was less affected and almost the same with the condition of 0 g x L(-1), both over 98%. When the salinity was increased to 10 g x L(-1), the NH4(+)-N removal rate dropped to 70%. Thus, increasing the salinity of wastewater not only affected the system nitrogen removal rate but also increased the amount of N2O production.

  20. Simulation of temporal and spatial change of N2O emissions in the Yangtze River Delta

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-dong; ZHOU Xiu-ji; CHEN De-liang; OUYANG Zhi-yun; WANG Xiao-ke; Achberger Christine

    2005-01-01

    A biogeochemical model(DNDC) is combined with a plant ecological model to estimate N2O emission from rice paddy fields in the Yangtze River Delta region. The model is driven by local meteorological, soil, and physiological data and is validated for 1999 and 2000 at a site in the region, which showed that the simulated N2O emissions agree fairly well with the observed data. This adds some confidence in the estimated N2O emissions during 1950 and 2000 in the Hangzhou Region. A significant correlation between the N2O emissions and the population for the Hangzhou Region is found, which is due to a combination of increased application of fertilizers and cultivated area.Such a correlation can not be established for the whole Yangtze River Delta region when the data of both urban and rural areas are included. However, when the data from the heavily urbanized areas are excluded, a significant correlation between population and N2O emissions emerges. The results show clearly that both the temporal and the spatial N2O emissions have significant positive relationship with population under traditional farming practice. These results have implications for suitable mitigation options towards a sustainable agriculture and environment in this region.

  1. Climate change and N2O emissions from South West England grasslands: A modelling approach

    Science.gov (United States)

    Abalos, Diego; Cardenas, Laura M.; Wu, Lianhai

    2016-05-01

    Unravelling the impacts of climate change on agriculture becomes increasingly important, as the rates and magnitude of its effects are accelerating. Current estimates of the consequences of climate change on nitrous oxide (N2O) emissions remain largely uncertain; there is a need for more consistent and comprehensive assessments of this impact. In this study we explored the implications of two IPCC climate change projections (high and medium emissions scenarios) on N2O emissions from South West England grasslands for the time slices of a baseline, the 2020s, the 2050s and the 2080s, employing a process-based model (SPACSYS). The model was initially calibrated and validated using datasets collected from three grassland sites of the region. Statistical analysis showed that simulated results had no significant total error or bias compared to measured values. We found a consistent increase in N2O emissions of up to 94% under future climate change scenarios compared to those under the baseline, and warming rather than precipitation variability was the overriding factor controlling the N2O rise. Modelling fertilizer forms showed that replacing ammonium-nitrate fertilizers with urea or slurry significantly reduced N2O emissions (c. 30%). Our study highlights the urgent necessity to adopt viable N2O mitigation measures now in order to avoid higher emissions in the future.

  2. Comparison of Urea-Derived N2O Emission from Soil and Soil-Plant System

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A pot experiment with a sandy loam soil and spring wheat as test crop was conducted to compare the N2O emission from soil system with plant cut off and from soil-plant system with plant kept. The results showed that after urea fertilizer applied, the N2O emission from soil and soil-wheat system decreased exponentially with time, and its total amount was 0.34%~0.63% and 0.33%~0.58% of applied urea-N respectively, no significant difference being found between these two systems. The N2O emission had a very significant negative relationship (P = 0.01) with the biomass of wheat plant. A combined application of urease inhibitor hydroquinone and nitrification inhibitor dicyandiamide could reduce the N2O emission by 50%~83% and 46%~74%, respectively, from soil and soil-wheat system. The N2O was mainly produced and emitted from soil, and the soil biochemical regulation, i.e., applying related inhibitors into soil could effectively diminish the urea derived N2O emission.

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

    DEFF Research Database (Denmark)

    Carter, Mette Sustmann

    2007-01-01

    and N(2)O loss ratio of nitrification (i.e. moles of N(2)O-N produced per moles of nitrate produced) and denitrification (i.e. moles of NO produced per moles of N(2)O + N(2) Produced). The effect of artificial urine (52.9 g N m(-2)) and ammonium solution (52.9g N m(-2)) was examined in separate...... experiments at 45% and 35% water-filled pore space (WFPS), respectively, and in each experiment a water control was included. The N(2)O loss derived from nitrification or denitrification was determined in the field immediately after application of (15)N-labelled solutions. During the next 24 h, gross...... 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...

  4. Optimizing rice plant photosynthate allocation reduces N2O emissions from paddy fields

    Science.gov (United States)

    Jiang, Yu; Huang, Xiaomin; Zhang, Xin; Zhang, Xingyue; Zhang, Yi; Zheng, Chengyan; Deng, Aixing; Zhang, Jun; Wu, Lianhai; Hu, Shuijin; Zhang, Weijian

    2016-07-01

    Rice paddies are a major source of anthropogenic nitrous oxide (N2O) emissions, especially under alternate wetting-drying irrigation and high N input. Increasing photosynthate allocation to the grain in rice (Oryza sativa L.) has been identified as an effective strategy of genetic and agronomic innovation for yield enhancement; however, its impacts on N2O emissions are still unknown. We conducted three independent but complementary experiments (variety, mutant study, and spikelet clipping) to examine the impacts of rice plant photosynthate allocation on paddy N2O emissions. The three experiments showed that N2O fluxes were significantly and negatively correlated with the ratio of grain yield to total aboveground biomass, known as the harvest index (HI) in agronomy (P < 0.01). Biomass accumulation and N uptake after anthesis were significantly and positively correlated with HI (P < 0.05). Reducing photosynthate allocation to the grain by spikelet clipping significantly increased white root biomass and soil dissolved organic C and reduced plant N uptake, resulting in high soil denitrification potential (P < 0.05). Our findings demonstrate that optimizing photosynthate allocation to the grain can reduce paddy N2O emissions through decreasing belowground C input and increasing plant N uptake, suggesting the potential for genetic and agronomic efforts to produce more rice with less N2O emissions.

  5. Full-scale post denitrifying biofilters: sinks of dissolved N2O?

    Science.gov (United States)

    Bollon, Julien; Filali, Ahlem; Fayolle, Yannick; Guerin, Sabrina; Rocher, Vincent; Gillot, Sylvie

    2016-09-01

    In this study, nitrous oxide (N2O) emissions from a full-scale denitrifying biofilter plant were continuously monitored over two periods (summer campaign in September 2014 and winter campaign in February 2015). Results of the summer campaign showed that the major part (>99%) of N2O flux was found in the liquid phase and was discharged with the effluent. N2O emissions were highly variable and represented in average 1.28±1.99% and 0.22±0.31% of the nitrate uptake rate during summer and winter campaigns, respectively. Denitrification was able to consume a large amount of dissolved N2O coming from the upstream nitrification stage. In the absence of methanol injection failure and with an influent BOD/NO3-N ratio higher than 3, average reduction of N2O was estimated to be of 93%. The control of exogenous carbon dosage is essential to minimize N2O production from denitrifying biofilters, in correlation to NO2-N concentrations in the filter.

  6. [Effects of applying controlled release fertilizers on N2O emission from a lateritic red soil].

    Science.gov (United States)

    Du, Ya-qin; Zheng, Li-xing; Fan, Xiao-lin

    2011-09-01

    Static closed chamber technique and contrast method were adopted to study the effects of three coated compound fertilizers (N:P2O5:K2O = 19:8.6:10.5, high N; 14.4:14.4:14.4, balanced NPK; and 12.5:9.6:20.2, high K) on the NO2O emission from a lateritic red soil under the condition of no crop planting, taking uncoated compound fertilizers (N:P2O5:K2O = 20:9:11, high N; 15:15:15, balanced NPK; and 13:10:21, high K) as the contrasts. Different formula of fertilizer NPK induced significant difference in the N2O emission. Under the application of uncoated compound fertilizers, the cumulative N2O emission was in the order of balanced NPK > or = high N > high K. Applying coated compound fertilizers decreased the N2O emission significantly, and the emission amount under the application of high N, balanced NPK, and high K was 34.4%, 30.5%, and 89.3% of the corresponding uncoated compound fertilizers, respectively. Comparing with the application of uncoated compound fertilizers, applying coated compound fertilizers also decreased the daily N2O flux significantly, and delayed and shortened the N2O peak, suggesting that coated fertilizers could reduce soil nitrogen loss and the global warming potential induced by N2O emission.

  7. Attenuation of N2O emission rates from agricultural soil at different dicyandiamide concentrations.

    Science.gov (United States)

    Verma, Amitosh; Tyagi, Larisha; Singh, S N

    2008-02-01

    An experiment was conducted to assess the role of different concentrations of dicyandiamide (DCD), a potent nitrification inhibitor, on temporal changes in nitrous oxide emission from sandy loam agricultural soil. It was found that with increasing concentration of DCD i.e. from 6 to 12% of nitrogen applied in the form of urea, there was a decrease in the both average and peak N(2)O emissions. However, from 14% DCD treated soil, there was a non-significant alteration in the N(2)O emission. Maximum average N(2)O efflux of 217.55 microg m(-2) h(-1) was noted from control plots. As compared to control, there was an attenuation of 50, 58, 65, and 91% average N(2)O efflux from 6, 8, 10 and 12% DCD applied pots, respectively, whereas, there was a negative average of N(2)O efflux from the soil with 14% DCD treatment. The soil N content also showed a significant correlation with N(2)O emission. Therefore, 12% DCD treatment has been found to be the best with regard to attenuation of nitrous oxide from sandy loam agricultural soils.

  8. 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.

  9. 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

  10. Understanding N2O sources and sinks with laser based isotopic analysis

    Science.gov (United States)

    Mohn, J.

    2015-12-01

    Nitrous oxide (N2O) is a potent greenhouse gas and the strongest stratospheric ozone-destroying substance released in the 21st century. Main N2O emissions are linked to different microbial pathways, therefore sources are disperse and highly variable, complicating their interpretation. Isotopic measurements have great potential to distinguish between individual source and sink processes. Developments in laser spectroscopy allow both the intramolecular distribution of 15N substitutions (15N14N16O versus 14N15N16O) and the oxygen isotopic composition of N2O to be measured in real-time, at high precision and in excellent compatibility to IRMS [1]. In a number of laboratory and pilot plant studies we investigated the isotopic signature of distinct microbial and abiotic N2O production and consumption pathways in soil and aqueous solution [e.g. 2-4]. Specific pathways were favoured by selection of the nitrogen substrates and process conditions and their isotopic signatures identified by real-time laser spectroscopic analysis. Results from our laboratory studies are in accordance with pure culture experiments and can therefore be applied to other ecosystems. High precision isotopic analysis at ambient N2O concentration is feasible by combining laser spectroscopy with automated preconcentration. Field deployment was demonstrated by real-time monitoring of the isotopic composition of N2O emissions above an intensively managed grassland in central Switzerland. The responses of the N2O isotopic signatures were analysed with respect to management events and climatic conditions [5]. In a follow-up project we combine real-time N2O isotopic analysis at a tall tower in central Switzerland with atmospheric transport simulations and a biogeochemical model of surface fluxes of N2O isotopomers. The working hypothesis is that this approach will allow us to quantify regional N2O sources, identify emission hot spots, and constrain source processes, which will significantly advance our

  11. 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

  12. Organically fertilized tea plantation stimulates N2O emissions and lowers NO fluxes in subtropical China

    Directory of Open Access Journals (Sweden)

    Z. Yao

    2015-07-01

    Full Text Available Tea plantations are rapidly expanding in China and other countries in the tropical and subtropical zones, but so far there are very few studies including direct measurements on nitrogenous gases fluxes from tea plantations. On the basis of 2 year field measurements from 2012 to 2014, we provided an insight into the assessment of annual nitrous oxide (N2O and nitric oxide (NO fluxes from Chinese subtropical tea plantations under three practices of conventional urea application, alternative oilcake incorporation and no nitrogen fertilization. Clearly, the N2O and NO fluxes exhibited large intra- and inter-annual variations, and furthermore their temporal variability could be well described by a combination of soil environmental factors including soil mineral N, water-filled pore space and temperature, based on a revised "hole-in-the-pipe" model. Averaged over 2 years, annual background N2O and NO emissions were approximately 4.0 and 1.6 kg N ha−1 yr−1, respectively. Compared to no nitrogen fertilization, both urea and oilcake application significantly stimulated annual N2O and NO emissions, amounting to 14.4–32.7 kg N2O-N ha−1 yr−1 and at least 12.3–19.4 kg NO-N ha−1 yr−1. In comparison with conventional urea treatment, on average, the application of organic fertilizer significantly increased N2O emission by 71 % but decreased NO emission by 22 %. Although the magnitude of N2O and NO fluxes was substantially influenced by N source, the annual direct emission factors of fertilizer N were estimated to be 2.8–5.9, 2.7–4.0 and 6.8–9.1 % for N2O, NO and N2O + NO, respectively, which are significantly higher than those defaults for global upland croplands. This indicated that the rarely determined N2O and NO formation appeared to be a significant pathway in the nitrogen cycle of tea plantations, which are a potential source of national nitrogenous gases inventory.

  13. 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...

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

    Science.gov (United States)

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

  15. Effects of dicyandiamide and dolomite application on N2O emission from an acidic soil.

    Science.gov (United States)

    Shaaban, Muhammad; Wu, Yupeng; Peng, Qi-an; Lin, Shan; Mo, Yongliang; Wu, Lei; Hu, Ronggui; Zhou, Wei

    2016-04-01

    Soil acidification is a major problem for sustainable agriculture since it limits productivity of several crops. Liming is usually adopted to ameliorate soil acidity that can trigger soil processes such as nitrification, denitrification, and loss of nitrogen (N) as nitrous oxide (N2O) emissions. The loss of N following liming of acidic soils can be controlled by nitrification inhibitors (such as dicyandiamide). However, effects of nitrification inhibitors following liming of acidic soils are not well understood so far. Here, we conducted a laboratory study using an acidic soil to examine the effects of dolomite and dicyandiamide (DCD) application on N2O emissions. Three levels of DCD (0, 10, and 20 mg kg(-1); DCD0, DCD10, and DCD20, respectively) were applied to the acidic soil under two levels of dolomite (0 and 1 g kg(-1)) which were further treated with two levels of N fertilizer (0 and 200 mg N kg(-1)). Results showed that N2O emissions were highest at low soil pH levels in fertilizer-treated soil without application of DCD and dolomite. Application of DCD and dolomite significantly (P ≤ 0.001) reduced N2O emissions through decreasing rates of NH4 (+)-N oxidation and increasing soil pH, respectively. Total N2O emissions were reduced by 44 and 13% in DCD20 and dolomite alone treatments, respectively, while DCD20 + dolomite reduced N2O emissions by 54% when compared with DCD0 treatment. The present study suggests that application of DCD and dolomite to acidic soils can mitigate N2O emissions.

  16. 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

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

    Directory of Open Access Journals (Sweden)

    C. A. M. Brenninkmeijer

    2002-11-01

    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, -0.044%o yr -1 for 2d15N and  -0.025%o yr -1 for  d18O. The total decrease since pre-industrial times is estimated to be about -2%o  for  d15N at both positions and -1.2%o  for  d18O. 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 anthropogenic 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.

  18. Understanding N2O sources and sinks with laser based isotopic analysis

    Science.gov (United States)

    Mohn, Joachim; Harris, Eliza; Tuzson, Béla; Emmenegger, Lukas

    2015-04-01

    Nitrous oxide (N2O) is a potent greenhouse gas and the strongest ozone-destroying substance. The main emissions of N2O are linked to different microbial processes, therefore the sources are disperse and highly variable, complicating the development of effective mitigation strategies. Isotopic measurements have great potential to unravel spatial and temporal variations in sources, sinks and chemistry of N2O. Recent developments in quantum cascade laser spectroscopy (QCLAS) [1] allow both the intermolecular distribution of 15N substitutions ('site preference'; 15N14N16O versus 14N15N16O) and the oxygen isotopic composition (d18O) of N2O to be measured in real-time and at high precision of weather influences [2]. In a follow-up project we intend to combine real-time N2O isotopic analysis at a tall tower in central Switzerland with atmospheric transport simulations and a biogeochemical model of surface fluxes of N2O isotopomers. The working hypothesis is that this approach will allow us to quantify regional N2O sources, identify emission hot spots, and constrain source processes, which will be of upmost importance for developing targeted mitigation options. References: [1] H. Wächter, J. Mohn, B. Tuzson, L. Emmenegger, M. W. Sigrist, Opt. Express (2008), 16, 9239-9244. [2] B. Wolf, L. Merbold, C. Decock, B. Tuzson, E. Harris, J. Six, L. Emmenegger, J. Mohn, Biogeosci. Discuss. (2015), accepted. [3] J. Mohn et al., Rapid Commun. Mass Spectrom. (2014) 28, 1995-2007. [4] P. Wunderlin, M. F. Lehmann, H. Siegrist, B. Tuzson, A. Joss, L. Emmenegger, J. Mohn, Environ. Sci. Technol. (2013), 47, 1339-1348. [5] J. Mohn, B. Tuzson, A. Manninen, N. Yoshida, S. Toyoda, W. A. Brand, L. Emmenegger, Atmos. Meas. Tech. (2012), 5, 1601-1609.

  19. Temporal trends in N2O flux dynamics in a Danish wetland – effects of plant-mediated gas transport of N2O and O2 following changes in water level and soil mineral-N availability

    DEFF Research Database (Denmark)

    Jørgensen, Christian Juncher; Struwe, Sten; Elberling, Bo

    2012-01-01

    in subsurface N2O and O2 concentrations, water level (WL), light intensity as well as mineral-N availability. Weekly concentration profiles showed that seasonal variations in N2O concentrations were directly linked to the position of the WL and O2 availability at the capillary fringe above the WL. N2O flux....... Complex interactions between seasonal changes in O2 and mineral-N availability following near-surface WL fluctuations in combination with plant-mediated gas transport by P. arundinacea controlled the subsurface N2O concentrations and gas transport mechanisms responsible for N2O fluxes across the soil...

  20. Methanogenic Conversion of CO2 Into CH4

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, S.H., Ferry, J.G., Schoell, M.

    2012-05-06

    This SBIR project evaluated the potential to remediate geologic CO2 sequestration sites into useful methane gas fields by application of methanogenic bacteria. Such methanogens are present in a wide variety of natural environments, converting CO2 into CH4 under natural conditions. We conclude that the process is generally feasible to apply within many of the proposed CO2 storage reservoir settings. However, extensive further basic R&D still is needed to define the precise species, environments, nutrient growth accelerants, and economics of the methanogenic process. Consequently, the study team does not recommend Phase III commercial application of the technology at this early phase.

  1. Comparison of N2O5 mixing ratios during NO3Comp 2007 in SAPHIR

    Directory of Open Access Journals (Sweden)

    A. W. Rollins

    2012-07-01

    Full Text Available N2O5 detection in the atmosphere has been accomplished using techniques which have been developed during the last decade. Most techniques use a heated inlet to thermally decompose N2O5 to NO3, which can be detected by either cavity based absorption at 662 nm or by laser-induced fluorescence. In summer 2007, a large set of instruments, which were capable of measuring NO3 mixing ratios, were simultaneously deployed in the atmosphere simulation chamber SAPHIR in Jülich, Germany. Some of these instruments measured N2O5 mixing ratios either simultaneously or alternatively. Experiments focussed on the investigation of potential interferences from e.g. water vapor or aerosol and on the investigation of the oxidation of biogenic volatile organic compounds by NO3. The comparison of N2O5 mixing ratios shows an excellent agreement between measurements of instruments applying different techniques (3 cavity ring-down (CRDS instruments, 2 laser-induced fluorescence (LIF instruments. Data sets are highly correlated as indicated by the square of the linear correlation coefficients, R2, which values are larger than 0.96 for the entire data sets. N2O5 mixing ratios well agree within the combined accuracy of measurements. Slopes of the linear regression range between 0.87 and 1.26 and intercepts are negligible. The most critical aspect of N2O5 measurements by cavity ring-down instruments is the determination of the inlet and filter transmission efficiency. Measurements here show that the N2O5 inlet transmission efficiency can decrease in the presence of high aerosol loads, and that frequent filter/inlet changing is necessary to quantitatively sample N2O5 in some environments. The analysis of data also demonstrates that a general correction for degrading filter transmission is not applicable for all conditions encountered during this campaign. Besides the effect of a gradual degradation of the inlet transmission efficiency aerosol exposure, no other interference

  2. Comparison of N2O5 mixing ratios during NO3Comp 2007 in SAPHIR

    Science.gov (United States)

    Fuchs, H.; Simpson, W. R.; Apodaca, R. L.; Brauers, T.; Cohen, R. C.; Crowley, J. N.; Dorn, H.-P.; Dubé, W. P.; Fry, J. L.; Häseler, R.; Kajii, Y.; Kiendler-Scharr, A.; Labazan, I.; Matsumoto, J.; Mentel, T. F.; Nakashima, Y.; Rohrer, F.; Rollins, A. W.; Schuster, G.; Tillmann, R.; Wahner, A.; Wooldridge, P. J.; Brown, S. S.

    2012-11-01

    N2O5 detection in the atmosphere has been accomplished using techniques which have been developed during the last decade. Most techniques use a heated inlet to thermally decompose N2O5 to NO3, which can be detected by either cavity based absorption at 662 nm or by laser-induced fluorescence. In summer 2007, a large set of instruments, which were capable of measuring NO3 mixing ratios, were simultaneously deployed in the atmosphere simulation chamber SAPHIR in Jülich, Germany. Some of these instruments measured N2O5 mixing ratios either simultaneously or alternatively. Experiments focused on the investigation of potential interferences from, e.g., water vapour or aerosol and on the investigation of the oxidation of biogenic volatile organic compounds by NO3. The comparison of N2O5 mixing ratios shows an excellent agreement between measurements of instruments applying different techniques (3 cavity ring-down (CRDS) instruments, 2 laser-induced fluorescence (LIF) instruments). Datasets are highly correlated as indicated by the square of the linear correlation coefficients, R2, which values were larger than 0.96 for the entire datasets. N2O5 mixing ratios well agree within the combined accuracy of measurements. Slopes of the linear regression range between 0.87 and 1.26 and intercepts are negligible. The most critical aspect of N2O5 measurements by cavity ring-down instruments is the determination of the inlet and filter transmission efficiency. Measurements here show that the N2O5 inlet transmission efficiency can decrease in the presence of high aerosol loads, and that frequent filter/inlet changing is necessary to quantitatively sample N2O5 in some environments. The analysis of data also demonstrates that a general correction for degrading filter transmission is not applicable for all conditions encountered during this campaign. Besides the effect of a gradual degradation of the inlet transmission efficiency aerosol exposure, no other interference for N2O5

  3. Viscosity controls humidity dependence of N2O5 uptake to citric acid aerosol

    Directory of Open Access Journals (Sweden)

    G. Gržinić

    2015-08-01

    Full Text Available The heterogeneous loss of dinitrogen pentoxide (N2O5 to aerosol particles has a significant impact on the night time nitrogen oxide cycle and therefore the oxidative capacity in the troposphere. Using a 13N short lived radioactive tracer method we studied the uptake kinetics of N2O5 on citric acid aerosol particles as a function of relative humidity (RH. The results show that citric acid exhibits lower reactivity than similar di- and polycarboxylic acids, with uptake coefficients between ~ 3 × 10−4–~ 3 × 10−3 depending on humidity (17–70 % RH. This humidity dependence can be explained by a changing viscosity and, hence, diffusivity in the organic matrix. Since the viscosity of highly concentrated citric acid solutions is not well established, we present four different parameterizations of N2O5 diffusivity based on the available literature data or estimates for viscosity and diffusivity. Above 50 % RH, uptake is consistent with the reacto-diffusive kinetic regime whereas below 50 % RH, the uptake coefficient is higher than expected from hydrolysis of N2O5 within the bulk of the particles, and the uptake kinetics may be limited by loss on the surface only. This study demonstrates the impact of viscosity in highly oxidized and highly functionalized secondary organic aerosol material on the heterogeneous chemistry of N2O5 and may explain some of the unexpectedly low loss rates to aerosol derived from field studies.

  4. Site selective real-time measurements of atmospheric N2O isotopomers by laser spectroscopy

    Directory of Open Access Journals (Sweden)

    W. A. Brand

    2012-07-01

    Full Text Available We describe the first high precision real-time analysis of the N2O site-specific isotopic composition at ambient mixing ratios. Our technique is based on mid-infrared quantum cascade laser absorption spectroscopy (QCLAS combined with an automated preconcentration unit. The QCLAS allows for simultaneous and specific analysis of the three main stable N2O isotopic species, 14N15N16O, 15N14N16O, 14N14N16O, and the respective site-specific relative isotope ratio differences δ15Nα and δ 15Nβ. Continuous, stand-alone operation is achieved by using liquid nitrogen free N2O preconcentration, a quasi-room-temperature quantum cascade laser (QCL, quantitative sample transfer to the QCLAS and an optimized calibration algorithm. The N2O site-specific isotopic composition (δ15Nα and δ15Nβ can be analysed with a long-term precision of 0.2‰. The potential of this analytical tool is illustrated by continuous N2O isotopomer measurements above a grassland plot over a three week period, which allowed identification of microbial source and sink processes.

  5. Monitoring the concentration of N2O in the Fildes Peninsula, maritime Antarctica

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Gases in the marine boundary layer in Fildes Peninsula, maritime Antarctica were sampled and analyzed for the first time. Sampling sites included areas covered by moss and lichen growth, penguin colonies and an area where scientific research stations are located. A total of 211 samples were analyzed for N2O concentrations, with an average of (321.33±3.07) nL/L. This is above the global average value of 314 nL/L. It is found that the N2O concentrations evidently increase during the summer months. Concentrations around the research stations are higher than at remote areas, indicating a potential source from human activities on the island. N2O concentrations at a large penguin colony on Barton Peninsula are the highest among the sampled areas. This may explain why N2O concentrations in Fildes Peninsula are higher than the global average. Our preliminary conclusions are that human activities and emissions from penguin dropping-amended soil and vegetation soil constitute the major sources of N2O in the maritime Antarctic atmosphere.

  6. Assessment of N2O emissions from rapeseed cultivation in Poland by various approaches

    Science.gov (United States)

    Syp, Alina; Faber, Antoni; Kozak, Małgorzata

    2016-10-01

    The aim of this study was to compare four tools for calculation of nitrous oxide (N2O) emissions under the renewable energy directive. All the tools follow the methodology of the international panel on climate change. The first calculations of N2O fluxes were based on the Tier 1 method using the BioGrace tool. The second and the third ones followed the Tier 2 methodology, applying the global nitrous oxide calculator and the Lesschen emission factors, respectively. The last assessment was performed in accordance with the Tier 3 approach by using the denitrification- decomposition model. The N2O fluxes were calculated for rapeseed cultivation in a 4-year crop rotation in Poland. The same input data were applied in all methods. The average of N2O emissions varied in the range of 1.99-3.78 kg N2O ha-1 y-1, depending on the approach used (Lesschen emission factors > denitrificationdecomposition > global nitrous oxide calculator > BioGrace). This paper illustrates that, at country level, the Lesschen emission factors method worked as well as the denitrification-decomposition model for Poland. The advantage of this approach is the simplicity of collecting the necessary data, in contrast to process-based modelling. Moreover, the Tier 2 method provides mitigation measures similar to the denitrification-decomposition model, related to crop type, climatic conditions, and management practices.

  7. [Vertical distribution characteristics of N2O emission in tea garden and its adjacent woodland].

    Science.gov (United States)

    Fan, Li-chao; Han, Wen-yan; Li, Xin; Li, Zhi-xin

    2015-09-01

    In this study, we determined the vertical distribution of N2O emission rates in tea soils and its adjacent woodland soils. The results showed that total nitrogen contents, N2O fluxes and cumulative emissions in the tea garden and woodland decreased with the increasing depth of the soil layer, and their average values were greater in tea garden than in woodland. Generally, pH, soil water soluble organic nitrogen (WSON), soil microbial biomass nitrogen (MBN), NO(3-)-N and NH(4+)-N contents had a downward trend with the increasing depth of soil layer. The WSON, MBN, NO(3-)-N and NH(4+)-N contents from each soil layer were greater in tea garden than in woodland, but the pH value in tea garden was lower than that in woodland. The N2O emission rate was significantly positively related with TN, MBN and NH(4+)-N contents, but not with pH value. The N2O emission rate was significantly correlated with WSON content in woodland, but not in tea garden. The N20 emission rate was significantly correlated with NO(3-)-N concentration in tea garden, but not in woodland. WSON/TN and N2O-N/SMBN were averagely greater than in tea garden in woodland, and SMBN/TN was opposite. These results indicated that tea soil was not conducive to accumulate nitrogen pool, maintain soil quality and its sustainable use compared to woodland.

  8. Theoretical Study on Structures and Properties of N2O--HOCI Complexes

    Institute of Scientific and Technical Information of China (English)

    YUAN,Kun; LIU,Yanzhi; MA,Weichao; TANG,Huian; ZHU,Yuancheng; ZHANG,Ji

    2009-01-01

    B3LYP/6-311++G** and MP2/6-311++G** calculations were used to analyze the interaction between hy-pochlorous acid (HOCI) and nitrous oxide (N2O). The results showed that there are six and four equilibrium geome-tries at the B3LYP/6-311++ G** and MP2/6-311 ++G** computational levels, respectively. The equilibrium geometries of S1 and S3 were confirmed to be transition states by analytical frequency computations, and the other equilibrium geometries as minima. Complexes of S3, S5 and S6 use the H(6) atom of HOCI as a proton donor and the terminal O(3) atom of N2O as an acceptor. However, S2 uses the terminal N(1) atom of N2O as an acceptor. As for S1 and S4, S1 uses the CI(4) atom of HOCI as a proton donor and the terminal N(1) atom of N2O as an acceptor; S4 uses the terminal O(3) atom of N2O as an acceptor. Interaction energy of the complexes corrected with basis set superposition error (BSSE) lies in the range of - 1.56-8.73 kJ.mol-1 at the B3LYP/6-311 ++ G** levels. The natural bond orbit (NBO) and atoms in molecules (AIM) theory were also applied to explain the structures and the properties of the complexes.

  9. Gliding arc plasma assisted N2O dissociation for monopropellant propulsion

    Science.gov (United States)

    Bosi, Franco J.; Dobrynin, Danil

    2017-01-01

    In this paper we address the capability of gliding arc (GA) discharges to promote plasma assisted combustion of nitrous oxide gas (N2O) for spacecraft monopropellant thruster applications. N2O is a ‘green’ propellant with interesting properties, but highly inert when used as monopropellant. Higher vibrational temperatures {{T}\\text{v}}>T , and hot spot localized dissociation, achieved within the GA reactor, are able to promote combustion of the gas. The vibrational temperature of the N2 second positive system is estimated by means of optical emission spectroscopy and reaches 5000 K, while the gas temperature reaches 1500 K the degree of N2O decomposition, estimated by FTIR measurements, ranged from 25 to 85%. A kinetic model for N2O dissociation is developed; the model shows that simply heating the gas in the same conditions is not enough to produce appreciable dissociation, providing further evidence of the catalytic action of the plasma. Results allow us to predict the propulsive efficiencies to be about 43%, with a thrust level of 37 mN; this result compares positively with the existing N2O resistojet technology.

  10. Quantifying Gas Flaring CH4 Consumption Using VIIRS

    Directory of Open Access Journals (Sweden)

    Xiaodong Zhang

    2015-07-01

    Full Text Available A method was developed to estimate the consumption of CH4 and the release of CO2 by gas flaring using VIIRS nighttime data. The results agreed with the field data collected at six stations in Bakken field, North Dakota, USA, within ±50%, as measured by mean relative errors and with a correlation coefficient of 0.75. This improved over the NOAA NightFire estimates, likely due to: (1 more stringent data selection using only the middle portion of cloud-free VIIRS nighttime imagery; (2 the use of a lower heating rate, which is more suitable for the field condition; and (3 more accurate efficiency factors in calculating completeness in combustion and conversion of total reaction energy into radiant energy that can be sensed by a satellite sensor. While using atmospherically-corrected data can further improve the estimate of CH4 consumption by ~10%, the major uncertainty remains as being the form factor of the flares, particularly the ratio of total surface area of a flare to the cross-section area that was seen by a satellite sensor.

  11. N2O emission characteristics and its affecting factors in rain-fed potato fields in Wuchuan County, China

    Science.gov (United States)

    Wang, Liwei; Wang, Cheng; Pan, Zhihua; Xu, Hui; Gao, Lin; Zhao, Peiyi; Dong, Zhiqiang; Zhang, Jingting; Cui, Guohui; Wang, Sen; Han, Guolin; Zhao, hui

    2016-12-01

    Representing an important greenhouse gas, nitrous oxide (N2O) emission from cultivated land is a hot topic in current climate change research. This study examined the influences of nitrogen fertilisation, temperature and soil moisture on the ammonia monooxygenase subunit A (amoA) gene copy numbers and N2O emission characteristics. The experimental observation of N2O fluxes was based on the static chamber-gas chromatographic method. The ammonia-oxidising bacteria (AOB) and ammonia-oxidising archaea (AOA) gene copy numbers in different periods were measured by real-time polymerase chain reaction (PCR). The results indicated that rain-fed potato field was a N2O source, and the average annual N2O emission was approximately 0.46 ± 0.06 kgN2O-N/ha/year. N2O emissions increased significantly with increase in fertilisation, temperatures below 19.6 °C and soil volumetric water content under 15%. Crop rotation appreciably decreases N2O emissions by 34.4 to 52.4% compared to continuous cropping in rain-fed potato fields. The significant correlation between N2O fluxes and AOB copy numbers implied that N2O emissions were primarily controlled by AOB in rain-fed potato fields. The research has important theoretical and practical value for understanding N2O emissions from rain-fed dry farmland fields.

  12. Rainfall reduction amplifies the stimulatory effect of nitrogen addition on N2O emissions from a temperate forest soil

    Science.gov (United States)

    Geng, Shicong; Chen, Zhijie; Han, Shijie; Wang, Fang; Zhang, Junhui

    2017-01-01

    Soil is a significant source of atmospheric N2O, and soil N2O emissions at a global scale are greatly affected by environment changes that include continuous deposition of atmospheric nitrogen and changing precipitation distribution. However, to date, field simulations of multiple factors that control the interaction between nitrogen deposition and precipitation on forest soil N2O emissions are scarce. In this study, we conducted a 2-year continuous assessment of N2O emissions from November 2012 to October 2014 at a nitrogen addition and rainfall reduction manipulation platform in an old broad-leaved Korean pine mixed forest at Changbai Mountain in northeastern China. We found that N2O emissions from control plots were 1.25 ± 0.22 kg N2O-N ha−1 a−1. Nitrogen addition significantly increased N2O emissions, with the emission factor of 1.59%. A 30% reduction in rainfall decreased N2O emissions by 17–45%. However, in combination, nitrogen addition and rainfall reduction increased N2O emissions by 58–140%, with the emission factor of 3.19%, and had a larger promotional effect than the addition of nitrogen alone. Our results indicated that drought slightly decreases forest soil N2O emission; however, with increasing deposition of atmospheric N in temperate forest soils, the effect of drought might become altered to increase N2O emission. PMID:28233839

  13. N2O emission characteristics and its affecting factors in rain-fed potato fields in Wuchuan County, China

    Science.gov (United States)

    Wang, Liwei; Wang, Cheng; Pan, Zhihua; Xu, Hui; Gao, Lin; Zhao, Peiyi; Dong, Zhiqiang; Zhang, Jingting; Cui, Guohui; Wang, Sen; Han, Guolin; Zhao, hui

    2017-05-01

    Representing an important greenhouse gas, nitrous oxide (N2O) emission from cultivated land is a hot topic in current climate change research. This study examined the influences of nitrogen fertilisation, temperature and soil moisture on the ammonia monooxygenase subunit A ( amoA) gene copy numbers and N2O emission characteristics. The experimental observation of N2O fluxes was based on the static chamber-gas chromatographic method. The ammonia-oxidising bacteria (AOB) and ammonia-oxidising archaea (AOA) gene copy numbers in different periods were measured by real-time polymerase chain reaction (PCR). The results indicated that rain-fed potato field was a N2O source, and the average annual N2O emission was approximately 0.46 ± 0.06 kgN2O-N/ha/year. N2O emissions increased significantly with increase in fertilisation, temperatures below 19.6 °C and soil volumetric water content under 15%. Crop rotation appreciably decreases N2O emissions by 34.4 to 52.4% compared to continuous cropping in rain-fed potato fields. The significant correlation between N2O fluxes and AOB copy numbers implied that N2O emissions were primarily controlled by AOB in rain-fed potato fields. The research has important theoretical and practical value for understanding N2O emissions from rain-fed dry farmland fields.

  14. Microbial community diversity of organically rich cassava sago factory waste waters and their ability to use nitrate and N2O added as external N-sources for enhancing biomethanation and the purification efficiency.

    Science.gov (United States)

    Rajendran, Ranjiitkumar; Soora, Maya; Dananjeyan, Balachandar; Ratering, Stefan; Krishnamurthy, Kumar; Benckiser, Gero

    2012-12-15

    Water shortage necessitated South Indian sago factory owners, extracting starch out of cassava tubers, to install biogas plants where a starch utilizing microbial community multiplies and reduces the biological oxygen demand (BOD) of the waste waters by presently about 30%. The purification efficiency of sago factory waste waters, rich in solid particles and having wide C/N ratios, around 250, through unstirred biogas plants needs to be improved. Our approach was to apply instead of animal slurry nitrate (NO3(-)) and nitrous oxide (N2O) as external N-sources anticipating a better N-distribution in the unstirred biogas plants. Estimated cell numbers, bacterial community changes, on the basis of 16S rRNA gene clone libraries and changing CO2-, CH4-, N2O releases due to the presence of nitrate or N2O suggest that acid tolerant Lactobacillus spp. dominate the biogas plant inflows (pH 3.5). They were very less or not found in the outflows (pH 7.3). Assumingly, the phyla Bacteroidetes (Prevotella spp.), Proteobacteria (Rhizobium spp., Defluvibacter sp.), Firmicutes (Megasphaera spp., Dialister spp., Clostridium spp.) and Synergistetes (Thermanaerovibrio spp.), not-detectable in the biogas plant inflows, replaced them. Anaerobes, about 400cellsml(-1) in the inflows, increased to about 10(6)cellsml(-1) in the outflows. The methane formation, as confirmed by the incubation experiments, suggests that methanogens must have been present among the anaerobes. In the biogas plant in- and outflows also about 300cellsml(-1) denitrifying bacteria and up to 10(4)cfu fungi were found. Despite the low number of denitrifying bacteria nitrate added to the biogas plant in- and outflows was widely consumed and added N2O decreased considerably. Thus, wide C/N ratios substrates like sago factory waste waters keep the N2O emissions low by using N2O either as electron acceptor or by incorporating it into the growing biomass what needs to be confirmed. The biogas plant inflow samples have

  15. Infrared Spectra and Band Strengths of Amorphous and Crystalline N2O

    Science.gov (United States)

    Hudson, R. L.; Loeffler, M. J.; Gerakines, P. A.

    2017-01-01

    Infrared transmission spectra from 4000 to 400 cm (exp -1), and associated band strengths and absorption coefficients, are presented for the first time for both amorphous and crystalline N2O. Changes in the spectra as a function of ice thickness and ice temperature are shown. New measurements of density, refractive index, and specific refraction are reported for amorphous and crystalline N2O. Comparisons are made to published results, and the most-likely reason for some recent disagreements in the literature is discussed. As with CO2, its isoelectronic congener, the formation of amorphous N2O is found to require greater care than the formation of amorphous solids from more-polar molecules.