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Sample records for n2o emission hotspots

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

    PubMed

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

    2013-10-01

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

  2. [Simulation of N2O emissions in agroecosystems].

    PubMed

    Liu, Jiandong; Zhou, Xiuji; Ding, Guoan; Ouyang, Zhiyun; Wang, Xiaoke

    2002-11-01

    A numerical model for simulating N2O emissions in agroecosystem was established. Validation of the model with the observed data showed that the model simulated the process of N2O emissions in fields fairly well. The numerical analysis showed that the N2O emissions were interrelated well with average temperature during rice growth periods. Analysis of N2O emissions and meteorological factors by using power spectrum found that the change of N2O emissions had 7-9 year cycles. Sensitivity test showed that the N2O emission increased with temperature enhancement. PMID:12619275

  3. Seasonal variations in N2O emissions from central California

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

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

  4. Diurnality of soil nitrous oxide (N2O) emissions

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    PubMed

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

    2012-06-19

    Nitrous oxide (N(2)O) is an important greenhouse gas (GHG) which has a global warming potential 310 times that of carbon dioxide (CO(2)) over a hundred year lifespan. N(2)O is generated during microbial nitrification and denitrification, which are common in aquaculture systems. To date, few studies have been conducted to quantify N(2)O emission from aquaculture. Additionally, very little is known with respect to the microbial pathways through which N(2)O is formed in aquaculture systems. This review suggests that aquaculture can be an important anthropogenic source of N(2)O emission. The global N(2)O-N emission from aquaculture in 2009 is estimated to be 9.30 × 10(10) g, and will increase to 3.83 × 10(11)g which could account for 5.72% of anthropogenic N(2)O-N emission by 2030 if the aquaculture industry continues to increase at the present annual growth rate (about 7.10%). The possible mechanisms and various factors affecting N(2)O production are summarized, and two possible methods to minimize N(2)O emission, namely aquaponic and biofloc technology aquaculture, are also discussed. The paper concludes with future research directions. PMID:22594516

  6. N2O EMISSIONS FROM FOSSIL FUEL COMBUSTION

    EPA Science Inventory

    The paper discusses on- line measurements from six full-scale, coal-fired utility boilers that indicate direct N2O emissions of <5 ppm. Laboratory and pilot-scale experiments conducted to further characterize direct N2O emissions are consistent with the field data indicating on-l...

  7. N2O emissions from full-scale nitrifying biofilters.

    PubMed

    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. PMID:27318446

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

    NASA Astrophysics Data System (ADS)

    Ley, Martin; Lehmann, Moritz F.; Niklaus, Pascal A.; Kuhn, Thomas; Luster, Jörg

    2016-04-01

    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 hotspots under field conditions, and of the microbial pathways that underlie net N2O production (ammonium oxidation, nitrifier-denitrification, and denitrification) is challenging because of their 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 relevant microbial pathways. Flood events have been shown to trigger moments of enhanced N2O emission through a close coupling of niches with high and low oxygen availabilities. This coupling might be modulated by microhabitat effects related to soil aggregate formation, root soil interactions 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 N-rich floodplain soils comprising different combinations of soil aggregate size classes and inert matrix material. These model soils were either planted with basket willow (Salix viminalis L.), mixed with leaf litter, or left untreated. Throughout a simulated flood event, we repeatedly measured the net N2O production rate. In addition, soil water content, redox potential, as well as C and N substrate availability were monitored. In order to gain insight into the sources of, and biogeochemical controls on N2O production, we also measured the bulk δ15N signature of the produced N2O, as well as its intramolecular 15N site preference (SP). In this presentation we focus on a period of enhanced N2O emission during the drying phase after 48 hrs of flooding. We will discuss the observed emission patterns in the context of possible treatment effects. Soils with large aggregates showed a

  9. UV-induced N2O emission from plants

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  10. Nitrogen fertiliser formulation: The impact on N2O emissions

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  11. N2O - direct versus indirect effects on emissions

    NASA Astrophysics Data System (ADS)

    Zechmeister-Boltenstern, Sophie; Kitzler, Barbara

    2013-04-01

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

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

    PubMed

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

    2012-08-01

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

  13. Oceanic N2O emissions in the 21st century

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  15. Oceanic N2O emissions in the 21st century

    NASA Astrophysics Data System (ADS)

    Martinez-Rey, Jorge; Bopp, Laurent; Gehlen, Marion; Tagliabue, Alessandro

    2013-04-01

    Climate change will cause multiple perturbations in ocean biogeochemistry during the next century. Changes in temperature, carbonate chemistry, salinity and dissolved oxygen concentration will drive changes which remain highly uncertain, especially in the oceanic nitrogen cycle. Of particular interest regarding feedbacks to the Earth System are the oceanic emissions of nitrous oxide. N2O is a powerful greenhouse gas with a residence time of more than 100 years in the atmosphere. Moreover, N2O has been identified as the leading ozone depletion emission since 2010. Oceanic N2O, with an annual contribution of 3.6 Tg N and hence 30% of the total natural sources, is produced by bacterial processes called nitrification and denitrification. These processes are enhanced in regions of high productivity, with denitrification occurring where oxygen concentrations are low, typically below 60 μmol/L. Different parameterizations for N2O production have been proposed over the past decade and considered by current ocean biogeochemical models. However, significant uncertainties remain in particular with respect to the future evolution of N2O production under climate change. We implemented several published parameterizations of N2O production into the biogeochemical model PISCES and estimated the change in N2O production, inventory and N2O sea-to-air flux between 2005 and 2100, under the high emission scenario RCP8.5. This approach is complemented by an offline analysis of 8 model output datasets which contributed to the Coupled Model Intercomparison Project (CMIP5). Projections of N2O flux from the ocean to the atmosphere yield a 5% decrease on average in 2100. North- and southwest basins in the Pacific and Atlantic oceans show the largest reduction in N2O emissions, while the flux tends to increase in regions where the Oxygen Minimum Zones (OMZs) are located, i.e., Eastern Tropical Pacific and Bay of Bengal. The projected expansion of the OMZs, from 6.5 to 8.5 106 km3in our

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

    NASA Astrophysics Data System (ADS)

    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 <250 µm representing small aggregates) and inert matrix material (glass beads of 150 - 250 µm size, or quartz sand of 2000 - 3200 µm size, respectively). Soils containing the different aggregate size groups were either planted with willow (Salix viminalis L.), mixed with leaf litter or left untreated. At several time points before, during and after a simulated flood event, we measure the net efflux rate of N2O. In addition, soil water content, redox potential as well as carbon and nitrogen substrate availability are monitored. In order to

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    Microbial production is the major source of N2O, the strongest greenhouse gas produced within the nitrogen cycle, and the most important stratospheric ozone destructant released in the 21st century. Wastewater treatment is an important and growing source of N2O, with best estimates predicting N2O emissions from this sector will have increased by >25% by 2020. Novel treatment employing partial nitritation-anammox, rather than traditional nitrification-denitrification, has the potential to achieve a neutral carbon footprint due to increased biogas production - if N2O production accounts for <0.5-1% of total nitrogen turnover. As a further motivation for this research, microbial pathways identified from wastewater treatment can be applied to our understanding of N cycling in the natural environment. This study presents the first online isotopic measurements of offgas N2O from a partial-nitritation anammox reactor 1. The measured N2O isotopic composition - in particular the N2O isotopic site preference (SP = δ15Nα - δ15Nβ) - was used to understand N2O production pathways in the reactor. When N2O emissions peaked due to high dissolved oxygen concentrations, low SP showed that N2O was produced primarily via nitrifier denitrification by ammonia oxidizing bacteria (AOBs). N2O production by AOBs via NH2OH oxidation, in contrast, did not appear to be important under any conditions. Over the majority of the one-month measurement period, the measured SP was much higher than expected following our current understanding of N2O production pathways 2. SP reached 41‰ during normal operating conditions and achieved a maximum of 45‰ when nitrite was added under anoxic conditions. These results could be explained by unexpectedly strong heterotrophic N2O reduction despite low dissolved organic matter concentrations, or by an incomplete understanding of isotopic fractionation during N2O production from NH2OH oxidation by AOBs - however the explanation most consistent with all

  19. Uncertainties in United States agricultural N2O emissions: comparing forward model simulations to atmospheric N2O data.

    NASA Astrophysics Data System (ADS)

    Nevison, C. D.; Saikawa, E.; Dlugokencky, E. J.; Andrews, A. E.; Sweeney, C.

    2014-12-01

    Atmospheric N2O concentrations have increased from 275 ppb in the preindustrial to about 325 ppb in recent years, a ~20% increase with important implications for both anthropogenic greenhouse forcing and stratospheric ozone recovery. This increase has been driven largely by synthetic fertilizer production and other perturbations to the global nitrogen cycle associated with human agriculture. Several recent regional atmospheric inversion studies have quantified North American agricultural N2O emissions using top-down constraints based on atmospheric N2O data from the National Oceanic and Atmospheric Administration (NOAA) Global Greenhouse Gas Reference Network, including surface, aircraft and tall tower platforms. These studies have concluded that global N2O inventories such as EDGAR may be underestimating the true U.S. anthropogenic N2O source by a factor of 3 or more. However, simple back-of-the-envelope calculations show that emissions of this magnitude are difficult to reconcile with the basic constraints of the global N2O budget. Here, we explore some possible reasons why regional atmospheric inversions might overestimate the U.S. agricultural N2O source. First, the seasonality of N2O agricultural sources is not well known, but can have an important influence on inversion results, particularly when the inversions are based on data that are concentrated in the spring/summer growing season. Second, boundary conditions can strongly influence regional inversions but the boundary conditions used may not adequately account for remote influences on surface data such as the seasonal stratospheric influx of N2O-depleted air. We will present a set of forward model simulations, using the Community Land Model (CLM) and two atmospheric chemistry tracer transport models, MOZART and the Whole Atmosphere Community Climate Model (WACCM), that examine the influence of terrestrial emissions and atmospheric chemistry and dynamics on atmospheric variability in N2O at U.S. and

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  1. Global and regional emissions estimates for N2O

    NASA Astrophysics Data System (ADS)

    Saikawa, E.; Prinn, R. G.; Dlugokencky, E. J.; Ishijima, K.; Dutton, G. S.; Hall, B. D.; Langenfelds, R.; Tohjima, Y.; Machida, T.; Manizza, M.; Rigby, M. L.; Odoherty, S. J.; Patra, P. K.; Harth, C.; Weiss, R. F.; Krummel, P. B.; van der Schoot, M.; Fraser, P.; Steele, P.; Aoki, S.; Nakazawa, T.; Elkins, J. W.

    2013-12-01

    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 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 years, most likely due

  2. Global and regional emissions estimates for N2O

    NASA Astrophysics Data System (ADS)

    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. B.; Steele, L. P.; Aoki, S.; Nakazawa, T.; Elkins, J. W.

    2013-07-01

    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 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 years, most likely

  3. Global and regional emissions estimates for N2O

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed

    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. PMID:26558709

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

    PubMed

    Jin, Yue; Wang, Dunqiu; Zhang, Wenjie

    2016-01-01

    N2O emission in the anaerobic ammonium oxidation (anammox) process is of growing concern. In this study, effects of substrate concentrations on N2O emissions were investigated in an anammox reactor. Extremely high N2O emissions of 1.67 % were led by high NH4-N concentrations. Results showed that N2O emissions have a positive correlation with NH4-N concentrations in the anammox reactor. Reducing NH4-N concentrations by recycling pump resulted in decreasing N2O emissions. In addition, further studies were performed to identify a key biological process that is contributed to N2O emissions from the anammox reactor. Based on the results obtained, Nitrosomonas, which can oxidize ammonia to nitrite, was deemed as the main sources of N2O emissions. PMID:27376009

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    This study examines N2O emission estimates from five different atmospheric inversion frameworks based on chemistry transport models (CTMs). The five frameworks differ in the choice of CTM, meteorological data, prior uncertainties and inversion method but use the same prior emissions and observation data set. The posterior modelled atmospheric N2O mole fractions are compared to observations to assess the performance of the inversions and to help diagnose problems in the modelled transport. Additionally, the mean emissions for 2006 to 2008 are compared in terms of the spatial distribution and seasonality. Overall, there is a good agreement among the inversions for the mean global total emission, which ranges from 16.1 to 18.7 TgN yr-1 and is consistent with previous estimates. Ocean emissions represent between 31 and 38% of the global total compared to widely varying previous estimates of 24 to 38%. Emissions from the northern mid- to high latitudes are likely to be more important, with a consistent shift in emissions from the tropics and subtropics to the mid- to high latitudes in the Northern Hemisphere; the emission ratio for 0-30° N to 30-90° N ranges from 1.5 to 1.9 compared with 2.9 to 3.0 in previous estimates. The largest discrepancies across inversions are seen for the regions of South and East Asia and for tropical and South America owing to the poor observational constraint for these areas and to considerable differences in the modelled transport, especially inter-hemispheric exchange rates and tropical convective mixing. Estimates of the seasonal cycle in N2O emissions are also sensitive to errors in modelled stratosphere-to-troposphere transport in the tropics and southern extratropics. Overall, the results show a convergence in the global and regional emissions compared to previous independent studies.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    PubMed Central

    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

    2016-01-01

    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. PMID:27324813

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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

    2016-01-01

    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. PMID:27324813

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

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

    PubMed

    Marques, Ricardo; Oehmen, Adrian; Pijuan, Maite

    2014-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    This study examines N2O emission estimates from 5 different atmospheric inversion frameworks. The 5 frameworks differ in the choice of atmospheric transport model, meteorological data, prior uncertainties and inversion method but use the same prior emissions and observation dataset. The mean emissions for 2006 to 2008 are compared in terms of the spatial distribution and seasonality. Overall, there is a good agreement among the inversions for the mean global total emission, which ranges from 16.1 to 18.7 Tg N yr-1 and is consistent with previous estimates. Ocean emissions represent between 31% and 38% of the global total compared to widely varying previous estimates of 24% to 38%. Emissions from the northern mid to high latitudes are likely to be more important, with a consistent shift in emissions from the tropics and subtropics to the mid to high latitudes in the Northern Hemisphere; the emission ratio for 0-30° N to 30-90° N ranges from 1.5 to 1.9 compared with 2.9 to 3.0 in previous estimates. The largest discrepancies across inversions are seen for the regions of South and East Asia and for tropical and South America owing to the poor observational constraint for these areas and to considerable differences in the modelled transport, especially inter-hemispheric exchange rates and tropical convection. Estimates of the seasonal cycle in N2O emissions are also sensitive to errors in modelled stratosphere-to-troposphere transport in the tropics and southern extra-tropics. Overall, the results show a convergence in the global and regional emissions compared to previous independent studies.

  15. N2O emission from a partial nitrification-anammox process and identification of a key biological process of N2O emission from anammox granules.

    PubMed

    Okabe, Satoshi; Oshiki, Mamoru; Takahashi, Yoshitaka; Satoh, Hisashi

    2011-12-01

    Emission of nitrous oxide (N(2)O) during biological wastewater treatment is of growing concern. The emission of N(2)O from a lab-scale two-reactor partial nitrification (PN)-anammox reactor was therefore determined in this study. The average emission of N(2)O from the PN and anammox process was 4.0±1.5% (9.6±3.2% of the removed nitrogen) and 0.1±0.07% (0.14±0.09% of the removed nitrogen) of the incoming nitrogen load, respectively. Thus, a larger part (97.5%) of N(2)O was emitted from the PN reactor. The total amount of N(2)O emission from the PN reactor was correlated to nitrite (NO(2)(-)) concentration in the PN effluent rather than DO concentration. In addition, further studies were performed to indentify a key biological process that is responsible for N(2)O emission from the anammox process (i.e., granules). In order to characterize N(2)O emission from the anammox granules, the in situ N(2)O production rate was determined by using microelectrodes for the first time, which was related to the spatial organization of microbial community of the granule as determined by fluorescence in situ hybridization (FISH). Microelectrode measurement revealed that the active N(2)O production zone was located in the inner part of the anammox granule, whereas the active ammonium consumption zone was located above the N(2)O production zone. Anammox bacteria were present throughout the granule, whereas ammonium-oxidizing bacteria (AOB) were restricted to only the granule surface. In addition, addition of penicillin G that inhibits most of the heterotrophic denitrifiers and AOB completely inhibited N(2)O production in batch experiments. Based on these results obtained, denitrification by putative heterotrophic denitrifiers present in the inner part of the granule was considered the most probable cause of N(2)O emission from the anammox reactor (i.e., granules). PMID:21996609

  16. Biologically produced volatile compounds: N2O emissions from soils

    NASA Technical Reports Server (NTRS)

    Banin, A.

    1985-01-01

    Tropospheric nitrous concentration has increased by 0.2 0.4% per year over the period 1975 to 1982, amounting to net addition to the atmosphere of 2.8 - 5.6 Tg N2O-N per year. This perturbation, if continued into the future, will affect stratospheric chemical cycles, and the thermal balance of the Earth. In turn it will have direct and indirect global effects on the biosphere. Though the budget and cycles of N2O on Earth are not yet fully resolved, accumulating information and recent modelling efforts permit a more complete evaluation and better definition of gaps in our knowledge.

  17. Surface Nitrification: A Major Uncertainty in Marine N2O Emissions

    NASA Technical Reports Server (NTRS)

    Zamora, Lauren M.; Oschlies, Andreas

    2014-01-01

    The ocean is responsible for up to a third of total global nitrous oxide (N2O) emissions, but uncertainties in emission rates of this potent greenhouse gas are high (approaching 100%). Here we use a marine biogeochemical model to assess six major uncertainties in estimates of N2O production, thereby providing guidance in how future studies may most effectively reduce uncertainties in current and future marine N2O emissions. Potential surface N2O production from nitrification causes the largest uncertainty in N2O emissions (estimated up to approximately 1.6 Tg N/yr (sup -1) or 48% of modeled values), followed by the unknown oxygen concentration at which N2O production switches to N2O consumption (0.8 Tg N/yr (sup -1)or 24% of modeled values). Other uncertainties are minor, cumulatively changing regional emissions by less than 15%. If production of N2O by surface nitrification could be ruled out in future studies, uncertainties in marine N2O emissions would be halved.

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  19. Elevated CO2 and O3 modify N turnover rates, but not N2O emissions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order to predict and mitigate future climate change, it is essential to understand effects of elevated CO2 (eCO2) and O3 (eO3) on N-cycling, including N2O emissions, due to plant mediated changes. This is of particular interest for agroecosystems, since N-cycling and N2O emissions are responsive ...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  2. Reducing N2O emissions from orchard using subsurfce drip irrigation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural soil is the major source for N2O emissions. Minimizing N2O emissions along with increasing N use efficiency, reducing leaching loss, and maintaining crop economic yield and quality can lead to increased sustainability of crop production. The main objective of this research is to evaluat...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-06-01

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

  5. Woody Debris: Denitrification Hotspots and N2O Production in Fluvial Systems

    EPA Science Inventory

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

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

    EPA Science Inventory

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

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

    NASA Astrophysics Data System (ADS)

    Quin, P.; Joseph, S.; Husson, O.; Donne, S.; Mitchell, D.; Munroe, P.; Phelan, D.; Cowie, A.; van Zwieten, L.

    2015-11-01

    Agricultural soils are the primary anthropogenic source of atmospheric nitrous oxide (N2O), contributing to global warming and depletion of stratospheric ozone. Biochar addition has shown potential to lower soil N2O emission, with the mechanisms remaining unclear. We incubated eucalypt biochar (550 °C) - 0, 1 and 5% (w/w) in Ferralsol at 3 water regimes (12, 39 and 54% WFPS) - in a soil column, following gamma irradiation. After N2O was injected at the base of the soil column, in the 0% biochar control 100% of expected injected N2O was released into headspace, declining to 67% in the 5% amendment. In a 100% biochar column at 6% WFPS, only 16% of the expected N2O was observed. X-ray photoelectron spectroscopy identified changes in surface functional groups suggesting interactions between N2O and the biochar surfaces. We have shown increases in -O-C = N /pyridine pyrrole/NH3, suggesting reactions between N2O and the carbon (C) matrix upon exposure to N2O. With increasing rates of biochar application, higher pH adjusted redox potentials were observed at the lower water contents. Evidence suggests that biochar has taken part in redox reactions reducing N2O to dinitrogen (N2), in addition to adsorption of N2O.

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

    PubMed Central

    Quin, P; Joseph, S; Husson, O; Donne, S; Mitchell, D; Munroe, P; Phelan, D; Cowie, A; Van Zwieten, L

    2015-01-01

    Agricultural soils are the primary anthropogenic source of atmospheric nitrous oxide (N2O), contributing to global warming and depletion of stratospheric ozone. Biochar addition has shown potential to lower soil N2O emission, with the mechanisms remaining unclear. We incubated eucalypt biochar (550 °C) – 0, 1 and 5% (w/w) in Ferralsol at 3 water regimes (12, 39 and 54% WFPS) – in a soil column, following gamma irradiation. After N2O was injected at the base of the soil column, in the 0% biochar control 100% of expected injected N2O was released into headspace, declining to 67% in the 5% amendment. In a 100% biochar column at 6% WFPS, only 16% of the expected N2O was observed. X-ray photoelectron spectroscopy identified changes in surface functional groups suggesting interactions between N2O and the biochar surfaces. We have shown increases in -O-C = N /pyridine pyrrole/NH3, suggesting reactions between N2O and the carbon (C) matrix upon exposure to N2O. With increasing rates of biochar application, higher pH adjusted redox potentials were observed at the lower water contents. Evidence suggests that biochar has taken part in redox reactions reducing N2O to dinitrogen (N2), in addition to adsorption of N2O. PMID:26615820

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

    PubMed

    Quin, P; Joseph, S; Husson, O; Donne, S; Mitchell, D; Munroe, P; Phelan, D; Cowie, A; Van Zwieten, L

    2015-01-01

    Agricultural soils are the primary anthropogenic source of atmospheric nitrous oxide (N2O), contributing to global warming and depletion of stratospheric ozone. Biochar addition has shown potential to lower soil N2O emission, with the mechanisms remaining unclear. We incubated eucalypt biochar (550 °C)--0, 1 and 5% (w/w) in Ferralsol at 3 water regimes (12, 39 and 54% WFPS)--in a soil column, following gamma irradiation. After N2O was injected at the base of the soil column, in the 0% biochar control 100% of expected injected N2O was released into headspace, declining to 67% in the 5% amendment. In a 100% biochar column at 6% WFPS, only 16% of the expected N2O was observed. X-ray photoelectron spectroscopy identified changes in surface functional groups suggesting interactions between N2O and the biochar surfaces. We have shown increases in -O-C = N /pyridine pyrrole/NH3, suggesting reactions between N2O and the carbon (C) matrix upon exposure to N2O. With increasing rates of biochar application, higher pH adjusted redox potentials were observed at the lower water contents. Evidence suggests that biochar has taken part in redox reactions reducing N2O to dinitrogen (N2), in addition to adsorption of N2O. PMID:26615820

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

    PubMed Central

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

    2013-01-01

    Nitrous oxide (N2O) is an important greenhouse gas and ozone depleter, but the global budget of N2O remains unbalanced. Currently, ∼25% of the global N2O emission is ascribed to uncultivated tropical soils, but the exact locations and controlling mechanisms are not clear. Here we present the first study of soil N2O emission from the Pantanal indicating that this South American wetland may be a significant natural source of N2O. At three sites, we repeatedly measured in situ fluxes of N2O and sampled porewater nitrate (NO3-) during the low water season in 2008 and 2009. In 2010, 10 sites were screened for in situ fluxes of N2O and soil NO3- content. The in situ fluxes of N2O were comparable to fluxes from heavily fertilized forests or agricultural soils. An important parameter affecting N2O emission rate was precipitation, inducing peak emissions of >3 mmol N2O m−2 day−1, while the mean daily flux was 0.43 ± 0.03 mmol N2O m−2 day−1. Over 170 days of the drained period, we estimated non-wetted drained soil to contribute 70.0 mmol N2O m−2, while rain-induced peak events contributed 9.2 mmol N2O m−2, resulting in a total N2O emission of 79.2 mmol N2O m−2. At the sites of repeated sampling, the pool of porewater nitrate varied (0.002-7.1μmolNO3-gdW-1) with higher concentrations of NO3- (p < 0.05) found in drained soil than in water-logged soil, indicating dynamic shifts between nitrification and denitrification. In the field, O2 penetrated the upper 60 cm of drained soil, but was depleted in response to precipitation. Upon experimental wetting the soil showed rapid O2 depletion followed by N2O accumulation and a peak emission of N2O (2.5 - 3.0mmolN2Om-2day-1). Assuming that the observed emission of N2O from these wetland soils is generally representative to the Pantanal, we suggest that this undisturbed tropical wetland potentially contributes ∼1.7% to the global N2O emission budget, a significant

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

    PubMed

    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. PMID:24351937

  12. Isotopic constraints on marine and terrestrial N2O emissions during the last deglaciation.

    PubMed

    Schilt, Adrian; Brook, Edward J; Bauska, Thomas K; Baggenstos, Daniel; Fischer, Hubertus; Joos, Fortunat; Petrenko, Vasilii V; Schaefer, Hinrich; Schmitt, Jochen; Severinghaus, Jeffrey P; Spahni, Renato; Stocker, Thomas F

    2014-12-11

    Nitrous oxide (N2O) is an important greenhouse gas and ozone-depleting substance that has anthropogenic as well as natural marine and terrestrial sources. The tropospheric N2O concentrations have varied substantially in the past in concert with changing climate on glacial-interglacial and millennial timescales. It is not well understood, however, how N2O emissions from marine and terrestrial sources change in response to varying environmental conditions. The distinct isotopic compositions of marine and terrestrial N2O sources can help disentangle the relative changes in marine and terrestrial N2O emissions during past climate variations. Here we present N2O concentration and isotopic data for the last deglaciation, from 16,000 to 10,000 years before present, retrieved from air bubbles trapped in polar ice at Taylor Glacier, Antarctica. With the help of our data and a box model of the N2O cycle, we find a 30 per cent increase in total N2O emissions from the late glacial to the interglacial, with terrestrial and marine emissions contributing equally to the overall increase and generally evolving in parallel over the last deglaciation, even though there is no a priori connection between the drivers of the two sources. However, we find that terrestrial emissions dominated on centennial timescales, consistent with a state-of-the-art dynamic global vegetation and land surface process model that suggests that during the last deglaciation emission changes were strongly influenced by temperature and precipitation patterns over land surfaces. The results improve our understanding of the drivers of natural N2O emissions and are consistent with the idea that natural N2O emissions will probably increase in response to anthropogenic warming. PMID:25503236

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

    PubMed Central

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

    2014-01-01

    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. PMID:24351937

  14. Marine animals significantly increase tundra N2O and CH4 emissions in maritime Antarctica

    NASA Astrophysics Data System (ADS)

    Zhu, Renbin; Liu, Yashu; Xu, Hua; Ma, Dawei; Jiang, Shan

    2013-12-01

    studies on greenhouse gas emissions from animals concentrated on domestic animals, with limited data available from wild animals. The number of marine animals is potentially large in coastal Antarctica. In this paper, N2O and CH4 emissions were investigated from a penguin colony, a seal colony, a skua colony, the adjacent animal-lacking tundra, and background tundra sites to test the effects of marine animals on their fluxes in maritime Antarctica. Extremely high N2O emissions occurred in the penguin puddles (mean 392 µg N2O m-2 h-1) and seal wallows (mean 579 µg N2O m-2 h-1). The N2O emissions from animal colony tundra (13-57 µg N2O m-2 h-1) are much higher than those from the animal-lacking tundra, whereas the background tundra showed negligible N2O fluxes. Penguin puddles and seal wallows were stronger CH4 emitters than animal colony tundra soils, while animal-lacking tundra soils were strong CH4 sinks. Overall high N2O and CH4 emissions were modulated by soil physical and chemical processes associated with marine animal activities: sufficient supply of the nutrients NH4+-N and NO3--N, total nitrogen, and total organic carbon from marine animal excreta, animal tramp, and high soil water-filled pore space. Laboratory incubation experiments further confirmed that penguin and seal colony soils produced much higher N2O and CH4 emissions than animal-lacking tundra soils. Our results indicate that marine animal colonies are the hot spots for N2O and CH4 emissions in maritime Antarctica, and even at the global scale, and current climate warming will further increase their emissions.

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

    NASA Astrophysics Data System (ADS)

    Nadeem, S.; Hansen, S.; Bleken, M.; Dörsch, P.

    2012-04-01

    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 significantly higher N2O emissions as compared with a non fertilized cereal reference during the GM year (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) resulting in generally higher N2O emissions during barley production. Addition of biogas residue (80 kg N ha-1) in 2010 to previously non mulched GM and unfertilized cereal plots (2009) had no significant effect on cumulative N2O emissions relative to a treatment receiving the same amount of N in form of mulched aboveground GM. Ley management (mulching vs. removing biomass in 2009) had no effect on N2O emissions during barley production in 2010. In general, organic amendments (previously mulched or harvested GM, biorest) increased N2O emissions relative to a reference treatment 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 reference treatment with 80 kg mineral N fertilization in 2010 (47 g N2O-N kg-1 N yield in barley grain).

  16. Upscaling N2O emissions at the watershed scale: role of land cover and topography

    NASA Astrophysics Data System (ADS)

    Vilain, G.; Garnier, J.; Passy, P.; Silvestre, M.; Billen, G.

    2012-04-01

    Agricultural basins are the major source of N2O emissions, with arable land accounting for half of the biogenic emissions worldwide. Moreover, N2O emissions strongly depend on the position of agricultural land in relation with topographical gradients, as footslope soils are often more prone to denitrification. The estimation of land surface area occupied by agricultural soils depends on the available spatial input information and resolution. Surface areas of grassland, forest and arable lands were estimated for the Orgeval sub-basin using two cover representations: the "Pan-European CORINE Land Cover 2006 database (CLC 2006) and a combination of two databases produced by the Institut d'Aménagement et d'Urbanisme de la Région d'Île-de-France (IAU IDF), the MOS (Mode d'Occupation des Sols) combined with the Ecomos 2000, a land-use classification. The two main objectives of this study were i) to establish a watershed-scale N2O budget taking into account direct emissions as well as indirect ones (by groundwater and rivers) and ii) to analyze the sensitivity of the input data used for the upscaling. We therefore analyzed how different land-cover representations influence and introduce errors into the results of regional N2O emissions inventories. A further introduction of the topography concept was used to better identify the critical zones for N2O emissions, a crucial issue to better adapt the strategies of N2O emissions mitigation. Overall, we observed that a refinement of the land-cover database led to a 5% decrease in the estimation of N2O emissions, while the integration of the topography decreased the estimation of N2O emissions up to 25%. An other significant result of this study is the small contribution to the total N2O emissions from indirect sources from the hydrological network (streams + groundwater) compared with direct emissions by soils.

  17. Contrasting denitrifier communities relate to contrasting N2O emission patterns from acidic peat soils in arctic tundra

    PubMed Central

    Palmer, Katharina; Biasi, Christina; Horn, Marcus A

    2012-01-01

    Cryoturbated peat circles (that is, bare surface soil mixed by frost action; pH 3–4) in the Russian discontinuous permafrost tundra are nitrate-rich ‘hotspots' of nitrous oxide (N2O) emissions in arctic ecosystems, whereas adjacent unturbated peat areas are not. N2O was produced and subsequently consumed at pH 4 in unsupplemented anoxic microcosms with cryoturbated but not in those with unturbated peat soil. Nitrate, nitrite and acetylene stimulated net N2O production of both soils in anoxic microcosms, indicating denitrification as the source of N2O. Up to 500 and 10 μ nitrate stimulated denitrification in cryoturbated and unturbated peat soils, respectively. Apparent maximal reaction velocities of nitrite-dependent denitrification were 28 and 18 nmol N2O gDW−1 h−1, for cryoturbated and unturbated peat soils, respectively. Barcoded amplicon pyrosequencing of narG, nirK/nirS and nosZ (encoding nitrate, nitrite and N2O reductases, respectively) yielded ≈49 000 quality-filtered sequences with an average sequence length of 444 bp. Up to 19 species-level operational taxonomic units were detected per soil and gene, many of which were distantly related to cultured denitrifiers or environmental sequences. Denitrification-associated gene diversity in cryoturbated and in unturbated peat soils differed. Quantitative PCR (inhibition-corrected per DNA extract) revealed higher copy numbers of narG in cryoturbated than in unturbated peat soil. Copy numbers of nirS were up to 1000 × higher than those of nirK in both soils, and nirS nirK−1 copy number ratios in cryoturbated and unturbated peat soils differed. The collective data indicate that the contrasting N2O emission patterns of cryoturbated and unturbated peat soils are associated with contrasting denitrifier communities. PMID:22134649

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

    PubMed

    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. PMID:15707336

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

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Mulder, J.; Wu, L. P.; Meng, X. X.; Wang, Y. H.; Dörsch, P.

    2013-03-01

    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.

  20. N(2)O emissions and source processes in snow-covered soils in the Swiss Alps.

    PubMed

    Mohn, Joachim; Steinlin, Christine; Merbold, Lutz; Emmenegger, Lukas; Hagedorn, Frank

    2013-01-01

    Nitrous oxide (N2O) emissions from snow-covered soils represent a significant fraction of the annual flux from alpine, subalpine or cold-temperate regions. In winter 2010-2011, we investigated the temporal variability of N2O emissions and source processes from a subalpine valley in the Swiss Alps. The study included regular measurements of N2O snow profiles at a fixed location and an intensive sampling campaign along a transversal cut through the valley with grassland at the bottom and coniferous forest at the slopes. During the intensive campaign, recently developed laser spectroscopy was employed for high-precision N2O isotopomer analysis. Maximum N2O fluxes (0.77±0.64 nmol m(-2) h(-1)) were found for periods with elevated air temperature and, in contrast to our expectations, were higher from forest than from grassland in mid-February. At maximum snow height (63 cm) the main N2O source processes were heterotrophic denitrification and nitrifier denitrification. The reduction of N2O by heterotrophic denitrifiers was much more pronounced for the grassland compared with the forest soil, as indicated by the (15)N site preferences of 16.4±11.5 ‰ (grassland) and-1.6±2.1 ‰ (forest). This illustrates the potential of laser spectroscopic N2O isotopomer analysis for the identification of source processes even at low emission rates in nutrient poor ecosystems. PMID:24313373

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

    Norberg, Lisbet; Berglund, Örjan; Berglund, Kerstin

    2016-04-01

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

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

    Nadeem, S.; Hansen, S.; Azzaroli Bleken, M.; Dörsch, P.

    2012-02-01

    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).

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

    NASA Astrophysics Data System (ADS)

    Nadeem, S.; Hansen, S.; Azzaroli Bleken, M.; Dörsch, P.

    2012-07-01

    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).

  6. Global N2O emissions - with a focus on natural soil

    NASA Astrophysics Data System (ADS)

    Saikawa, E.; Schlosser, C. A.; Rigby, M. L.; Prinn, R. G.; Weiss, R. F.; Fraser, P.; Krummel, P. B.; Steele, P.; Odoherty, S. J.; Simmonds, P.; Dlugokencky, E. J.; Elkins, J. W.; Dutton, G. S.; Hall, B. D.; Tohjima, Y.; Machida, T.; Nakazawa, T.; Aoki, S.; Ishijima, K.

    2011-12-01

    Nitrous oxide (N2O) emissions weighted by ozone depletion potential currently dominate emissions of ozone depleting substances, and N2O is now the third most significant long-lived anthropogenic greenhouse gas after CO2 and CH4. Despite its impact on stratospheric ozone destruction, it is not regulated under the Montreal Protocol, and global observations show a continuous N2O mole fraction increase of 0.2 to 0.3% per year. Sinks and sources of N2O still have large uncertainties but previous studies have estimated that soil emissions share more than a half of the global total. Because the variability in soil emissions could potentially have important implications for regional and global climate, and vice versa, it is essential to better understand the processes and feedbacks associated with soil N2O emissions. To achieve this goal and quantify global soil N2O emissions, we have included nitrification-denitrification processes (DNDC) into the Community Land Model (CLM) version 3.5. Using three different bias-corrected, reanalysis-based meteorological datasets (NCC, CAS and GOLD), we constructed a suite of global gridded soil N2O emissions estimates from 1975 through the mid-2000s. We evaluate our global soil N2O flux estimates against: 1) an existing emissions inventory (GEIA), 2) another process model (NASA-CASA), and 3) observations from an existing forest N2O flux dataset in the Amazon and in the United States. Both the global and regional totals agree well and the model reproduces the observed seasonal cycles of N2O emissions. Next, we input these emission estimates to a 3-dimensional atmospheric chemical transport model - the Model for OZone And Related Tracers (MOZART) version 4 - to analyze the impact of monthly and inter-annual variability in soil emissions on atmospheric observations. Using these emissions as an initial estimate, we also determine new regional and global N2O emissions by inverse modeling from 1995 through 2009. Data from the Advanced Global

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

    NASA Technical Reports Server (NTRS)

    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.

  8. N2O emissions: modeling the effect of process configuration and diurnal loading patterns.

    PubMed

    Houweling, Dwight; Wunderlin, Pascal; Dold, Peter; Bye, Chris; Joss, Adriano; Siegrist, Hansruedi

    2011-12-01

    The objective of this research was to develop a mechanistic model for quantifying N2O emissions from activated sludge plants and demonstrate how this may be used to evaluate the effects of process configuration and diurnal loading patterns. The model describes the mechanistic link between the factors recognized to correlate positively with N2O emissions. The primary factors are the presence of ammonia and nitrite accumulation. Low dissolved oxygen concentrations also may be implicated through differential impacts on ammonia-oxidizing bacteria (AOB) versus nitrite-oxidizing bacteria (NOB) activity. Factors promoting N2O emissions at treatment plants are discussed below. The model was applied to data from laboratory and pilot-scale systems. From a practical standpoint, plant configuration (e.g., plug-flow versus complete-mix), influent loading patterns (and peak load), and certain operating strategies (e.g., handling of return streams) are all important in determining N2O emissions. PMID:22368954

  9. Minimisation of N2O emissions from a plant-soil system under landfill leachate irrigation.

    PubMed

    Zhang, Hou-Hu; He, Pin-Jing; Shao, Li-Ming; Yuan, Li

    2009-03-01

    The irrigation of a plant-soil system with landfill leachate should promote the formation of N2O due to the introduction of organic carbon and mineralized-N and the elevation of the moisture content. Laboratory incubation was performed to minimize N2O emissions from a leachate irrigated plant-soil system by manipulating leachate NH(4)(+)-N loading, moisture content, and soil type. A field investigation, consisting of three plots planted with Cynodon dactylon, Nerium indicum Mill, and Festuca arundinacea Schreb, was then conducted to select plant species. There was almost no difference in N2O emissions between soil moisture contents of 46% and 55% water-filled pore space (WFPS), while a sharp increase occurred at 70% WFPS. N2O fluxes were significantly correlated with leachate NH4(+)-N loading. Amongst the physiochemical characteristics of the selected nine soils, only soil pH was significantly correlated with N2O fluxes. Compared with fertilizers application in other ecosystems, N2O turnover rate from the plant-soil system under leachate irrigation was relatively lower. Therefore, avoiding high NH4(+)-N loadings and excessively wet conditions (<60% WFPS) and cultivating conifer plants of stronger sunlight penetration with less litter deposit on acidic sandy soil could minimize potential N2O emissions under leachate irrigation. PMID:18835706

  10. Emission of N2O and CH4 from a constructed wetland in southeastern Norway.

    PubMed

    Søvik, A K; Kløve, B

    2007-07-15

    The Skjønhaug constructed wetland (CW) is a free surface water (FSW) wetland polishing chemically treated municipal wastewater in southeastern Norway and consists of three ponds as well as trickling, unsaturated filters with light weight aggregates (LWA). Fluxes of nitrous oxide (N(2)O) and methane (CH(4)) have been measured during the autumn, winter and summer from all three ponds as well as from the unsaturated filters. Physicochemical parameters of the water have been measured at the same localities. The large temporal and spatial variation of N(2)O fluxes was found to cover a range of -0.49 to 110 mg N(2)O-N m(-2) day(-1), while the fluxes of CH(4) was found to cover a range of -1.2 to 1900 mg m(-2) day(-1). Thus, both emission and consumption occurred. Regarding fluxes of N(2)O there was a significant difference between the summer, winter and autumn, with the highest emissions occurring during the autumn. The fluxes of CH(4) were, on the other hand, not significantly different with regard to seasons. Both the emissions of N(2)O and CH(4) were positively influenced by the amount of total organic carbon (TOC). The measured fluxes of N(2)O and CH(4) are in the same range as those reported from other CWs treating wastewater. There was an approximately equal contribution to the global warming potential from N(2)O and CH(4). PMID:17204306

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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. PMID:22126050

  13. Modeling of N2O emissions from soils in terrestrial ecosystems

    NASA Astrophysics Data System (ADS)

    Jain, A. K.; Jin, Y.; El-Masri, B.; Yang, X.

    2013-12-01

    Nitrous oxide (N2O) is not only one of the most important greenhouse gases, it also impacts stratospheric ozone. Soils under natural vegetation and agriculture are one of the main sources of N2O through nitrification and denitrification processes. Current estimates of N2O emissions on regional to global scales are based on the upscaling of limited measurements from specific measurement sites. These estimates have large uncertainties because of the heterogeneity of soils and the seasonal and interannual variability in the processes that control the nitrification/denitrification of soils. Here we employ a land surface model, the Integrated Science Assessment Model (ISAM), to model the N2O emissions from terrestrial ecosystems during the historical time period. In addition, we investigate the impacts of increasing CO2, climate change, N deposition, and land use change on the N2O emissions from soil over the historical time period. ISAM incorporates a fully prognostic carbon and nitrogen cycle component, coupled with biogeophysical processes. The N cycle module in the ISAM was calibrated with field experiment data, which includes representation of nitrogen immobilization, mineralization, nitrification and denitrification processes. In comparison to field measurements, the model is able to capture the temporal trends and magnitude of the N2O emissions. The climate and soil moisture control on N2O emissions are reflected in the model simulations and compared well with the observations. The calibrated and validated model was applied on the global scale to study the sources of N2O from terrestrial ecosystems. Our results show that tropical forest and tropical savanna are the major sources of N2O emissions, while there are very low emissions at the high latitude regions, which are consistent with both measurements and previous modeling studies. Our preliminary results also show that N2O emissions are sensitive to climate change, but not to CO2. In addition, N deposition and

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

    NASA Astrophysics Data System (ADS)

    Pusede, S.; Diskin, G. S.

    2015-12-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2015-01-01

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

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

    PubMed

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

    2016-01-01

    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. PMID:27378420

  18. Denitrification and N2O emission from forested and cultivated alluvial clay soil

    USGS Publications Warehouse

    Ullah, S.; Breitenbeck, G.A.; Faulkner, S.P.

    2005-01-01

    Restored forested wetlands reduce N loads in surface discharge through plant uptake and denitrification. While removal of reactive N reduces impact on receiving waters, it is unclear whether enhanced denitrification also enhances emissions of the greenhouse gas N2O, thus compromising the water-quality benefits of restoration. This study compares denitrification rates and N2O:N2 emission ratios from Sharkey clay soil in a mature bottomland forest to those from an adjacent cultivated site in the Lower Mississippi Alluvial Valley. Potential denitrification of forested soil was 2.4 times of cultivated soil. Using intact soil cores, denitrification rates of forested soil were 5.2, 6.6 and 2.0 times those of cultivated soil at 70, 85 and 100% water-filled pore space (WFPS), respectively. When NO3 was added, N2O emissions from forested soil were 2.2 times those of cultivated soil at 70% WFPS. At 85 and 100% WFPS, N2O emissions were not significantly different despite much greater denitrification rates in the forested soil because N2O:N2 emission ratios declined more rapidly in forested soil as WFPS increased. These findings suggest that restoration of forested wetlands to reduce NO3 in surface discharge will not contribute significantly to the atmospheric burden of N2O. ?? Springer 2005.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27378420

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

    NASA Astrophysics Data System (ADS)

    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.

  1. Detailed regional predictions of N2O and NO emissions from a tropical highland rainforest

    NASA Astrophysics Data System (ADS)

    Gharahi Ghehi, N.; Werner, C.; Hufkens, K.; Kiese, R.; Van Ranst, E.; Nsabimana, D.; Wallin, G.; Klemedtsson, L.; Butterbach-Bahl, K.; Boeckx, P.

    2013-01-01

    Tropical forest soils are a significant source for the greenhouse gas N2O as well as for NO, a precursor of tropospheric ozone. However, current estimates are uncertain due to the limited number of field measurements. Furthermore, there is considerable spatial and temporal variability of N2O and NO emissions due to the variation of environmental conditions such as soil properties, vegetation characteristics and meteorology. In this study we used a process-based model (ForestDNDC-tropica) to estimate N2O and NO emissions from tropical highland forest (Nyungwe) soils in southwestern Rwanda. To extend the model inputs to regional scale, ForestDNDC-tropica was linked to an exceptionally large legacy soil dataset. There was agreement between N2O and NO measurements and the model predictions though the ForestDNDC-tropica resulted in considerable lower emissions for few sites. Low similarity was specifically found for acidic soil with high clay content and reduced metals, indicating that chemo-denitrification processes on acidic soils might be under-represented in the current ForestDNDC-tropica model. The results showed that soil bulk density and pH are the most influential factors driving spatial variations in soil N2O and NO emissions for tropical forest soils. The area investigated (1113 km2) was estimated to emit ca. 439 ± 50 t N2O-N yr-1 (2.8-5.5 kg N2O-N ha-1 yr-1) and 244 ± 16 t NO-N yr-1 (0.8-5.1 kg N ha-1 yr-1). Consistent with less detailed studies, we confirm that tropical highland rainforest soils are a major source of atmospheric N2O and NO.

  2. Fertilizer-induced emission factors and background emissions of N 2 O from vegetable fields in China

    NASA Astrophysics Data System (ADS)

    Wang, Jinyang; Xiong, Zhengqin; Yan, Xiaoyuan

    2011-12-01

    The estimation of nitrous oxide (N 2O) emissions based on specific cropping systems is important for accurate national N 2O budgets. Intensively managed vegetable cultivation is responsible for large N 2O emissions in mainland China. However, little information can be obtained on the nationwide estimation of direct N 2O emissions from vegetable fields. Estimates of fertilizer-induced direct N 2O emissions from vegetable fields in mainland China were thus obtained by compiling and analyzing reported data in peer-reviewed journals and research reports. The results indicated that the seasonal N 2O emissions from vegetable fields significantly increased with nitrogen (N) fertilizer application ( p < 0.0001). According to the ordinary least squares (OLS) model, the fertilizer-induced emission factor (EF) and background emissions of N 2O were estimated to be 0.55 ± 0.05% and 1.067 ± 0.277 kg N ha -1 yr -1, respectively. The EF was reduced and the background emission of N 2O increased when the measurement duration was prolonged from ≤100 d to >100 and ≤200 d. Comparable results were obtained by the maximum likelihood (ML) model, with an EF of 0.49 ± 0.06% and background N 2O emissions of 1.228 ± 0.189 kg N ha -1 yr -1. Based on the OLS-derived parameters, the fertilizer-induced direct emissions and background emissions of N 2O were estimated to be 66.95 Gg N and 19.63 Gg N, respectively, in 2009, and the annual N 2O emissions were much higher in the provinces of Shandong, Henan, Hebei and Sichuan. The estimated N 2O emissions from vegetable fields accounted for 21.4% of the total direct N 2O emissions from Chinese croplands, with large uncertainties. Therefore, the EF and background emissions of N 2O for each cropping system, particularly for intensively managed vegetable fields, should be specifically determined for accurate national N 2O inventories.

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

    PubMed

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

    2014-11-15

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

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

    PubMed

    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. PMID:26620858

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

    PubMed

    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. PMID:23229048

  6. Long-term effect of temperature on N2O emission from the denitrifying activated sludge.

    PubMed

    Wang, Xiaojun; Yang, Xiaoru; Zhang, Zhaoji; Ye, Xin; Kao, Chih Ming; Chen, Shaohua

    2014-03-01

    The long-term effect of various temperature (4°C, 12°C, 20°C, 25°C and 34°C) on nitrous oxide (N2O) emission from lab-scale denitrifying activated sludge was studied in terms of activation energy, abundance of functional gene nosZ and its transcription. Results showed that temperature had a positive effect on N2O emissions as well as the maximum biomass-specific reduction rates of N2O and NO3(-), ranging from 0.006% to 0.681% of (N2O + N2), 17.3-116.2 and 5.2-66.2 mg N g(-1) VSS h(-1), respectively. The activation energies (Ea) for N2O and NO3(-) reduction of 44.1 kJ mol(-1) and 54.9 kJ mol(-1), shed light on differences in denitrifying rate variation. The maximum NO3(-) reduction rates were more sensitive to temperature variation than the corresponding N2O reduction rates under long-term acclimation. As a result, the ratio between N2O and NO3(-) reduction rates declined to 1.87 at 34°C from 3.31 at 4°C, suggesting great potential capacity for N2O losses at high temperature. The copy numbers of denitrifiers as nosZ gene (×10(8) copies mL(-1)) and total bacteria as 16S rRNA gene (×10(10) copies mL(-1)) did not show obvious relationship with temperature, having relative abundance of 0.42% on average. The transcriptional regulation of nosZ gene, in the range of 10(8)-10(5) copies mL(-1), was affected by reductase activity, substrate concentration as well as its duration. The active nosZ gene expression was accompanied with low reductase capacity, high dissolved N2O and the duration of N2O accumulation. These results provide insights into activation energy and gene expression responsible for N2O emission. PMID:24480748

  7. [County-scale N2O emission inventory of China's manure management system].

    PubMed

    Wang, Chuan; Gao, Wei; Zhou, Feng; Chen, Qing; Ying, Na; Xu, Peng; Hou, Xi-Kang

    2013-10-01

    Manure is one of the two largest contributors to China's N2O emission. By using the county-scale activity data and the regional emission factors and related parameters with spatial differentiation in China in 2008, this paper assessed the N2O emission loading, sources profile, spatial pattern, and uncertainty, aimed to establish a high-resolution N2O emission inventory of China's manure management system in 2008. As compared with the research results based on the IPCC, EDGAR, and other works, the proposed emission inventory was more reliable and comprehensive. The total China' s N2O emission from manure in 2008 was estimated as 572 Gg, among which, the emission from the manure except pasture/range/paddock was 322 Gg (56.3%), from the manure in pasture/range/paddock was 180 Gg (31.5%), and the indirect emission from atmospheric volatilized N deposition and leaching/runoff was 45.8 Gg (8.0%) and 1.23 Gg (0.2%), respectively. The spatial pattern of China's N2O emission from manure was more centralized, and mainly concentrated in Jilin, Shandong, Sichuan, Hunan, Henan, Heilongjiang, and Liaoning provinces, contributing 52.4% of the total emission, and more than 25% being from 84 counties (only < 3% of the whole counties). The proposed emission inventory had a higher spatial resolution and accuracy. Different with this inventory, the IPCC underestimated the direct emission while overestimated the indirect emission, with the regions of higher emission rate being underestimated by -1.5%-6.0% and those of lower emission rate being overestimated by 1.6%-13%. As for the EDGAR, the regions of higher emission rate were underestimated by -18. 8--50.0%, and those of lower emission rate were mostly overestimated by 25%-54.1%. PMID:24483097

  8. Biochar suppression of N2O emissions from an agricultural soil: effects and potential mechanisms

    NASA Astrophysics Data System (ADS)

    Case, S. D. C.; Whitaker, J.; McNamara, N. P.; Reay, D. S.

    2012-04-01

    Biochar is biomass that has been heated in a low-oxygen environment to between 350 and 800°C that is subsequently used as a soil amendment. As well as benefits to soil fertility, biochar has potential as a tool to mitigate climate change on a large scale due to its recalcitrance, high carbon content and observed effect of reducing soil greenhouse gas emissions. Previous studies have shown that biochar-amended soil may emit less nitrous oxide (N2O) than soil alone. Our aim was to investigate the effect of fresh, hardwood biochar on N2O emissions from a clay agricultural soil from Lincolnshire, United Kingdom with a combination of field and laboratory studies. We then investigated the mechanism to try to explain the observed suppression of N2O emissions with biochar. In biochar-amended field plots, quarterly greenhouse gas measurements over two years have recorded one occurrence of significant suppression of N2O emissions (80%), with other measurements showing generally low emissions of N2O across all treatments. In laboratory experiments, biochar suppressed N2O emissions following simulated rainfall events in a low-N agricultural soil (72 % suppression), in the same field-moist soil incubated with biochar in the field for 10 months (40 % suppression) and in a relatively high-N soil from a neighbouring field (83 % suppression). We hypothesised that biochar amendment may suppress soil N2O emissions by increasing the water holding capacity (WHC) of the soil, thus rendering the biochar-amended soil less anaerobic compared to control soil at the same gravimetric water content. Water was added to raise soil to the same WHC (87 %) with and without biochar at a range of addition rates. Biochar significantly suppressed N2O emissions with 5 % biochar addition by 67 % and 10 % biochar addition by 98 %. We concluded that the increased WHC of biochar-amended soil could not explain the suppression of N2O emissions. Subsequently, we formulated two hypotheses: (1) that biochar may

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

    NASA Astrophysics Data System (ADS)

    Yao, Z.; Wei, Y.; Liu, C.; Zheng, X.; Xie, B.

    2015-10-01

    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 of nitrogenous gas 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 a 2-year study, 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, respectively. 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 the source of N, the annual direct emission factors of N fertilizer 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.

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

    NASA Astrophysics Data System (ADS)

    Yao, Z.; Wei, Y.; Liu, C.; Zheng, X.; Xie, B.

    2015-07-01

    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.

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

    PubMed

    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. PMID:26785543

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

    PubMed Central

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

    2014-01-01

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

  13. Biochar application reduces N2O emission in intensively managed temperate grassland

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    Biochar, a pyrolysis product of organic residues, is seen as an amendment for agricultural soils to improve soil fertility, sequester CO2 and reduce N2O emissions. Mainly used in highly weathered tropical soils, the interest of using biochar in intensively managed temperate soils is increasing. Our previous laboratory incubations have shown N2O reduction potentials of between 20 and 100% for temperate soils after biochar application (Felber et al., Biogeosciences Discuss, 2012). To assess the effect of biochar application under field conditions, a plot experiment (3 control vs. 3 biochar amended plots of 3x3 m size at a rate of 15 t ha-1) was set up in a temperate intensively managed grassland soil. N2O and CO2 emissions were quasi-continuously measured by static chambers under standard management practice over 8 months. In parallel soil samples were taken monthly from all plots and their N2O and CO2 productions were measured under controlled conditions in the lab. At the beginning of the field measurements (April 2011) cumulative N2O fluxes from biochar amended plots were above those of control plots, but the pattern reversed towards reduced fluxes from biochar plots after 3 months and the reduction reached about 15% by the end of 2011. The biochar effect on reducing N2O emissions in the laboratory was two times that of the field measurements, indicating that results from laboratory experiments are not directly transferable to field conditions. The experiments indicate a substantial N2O emission reduction potential of biochar in temperate grassland fields.

  14. N2O emissions and carbon sequestration in a nitrogen-fertilized Douglas fir stand

    NASA Astrophysics Data System (ADS)

    Jassal, Rachhpal S.; Black, T. Andrew; Chen, Baozhang; Roy, Real; Nesic, Zoran; Spittlehouse, D. L.; Trofymow, J. A.

    2008-12-01

    This study investigated how nitrogen (N) fertilization with 200 kg N ha-1 of a 58-year-old West Coast Douglas fir stand influenced its net greenhouse gas (GHG) global warming potential (GWP) in the first year after fertilization. Effects of fertilization on GHG GWP were calculated considering changes in soil N2O emissions, measured using the static chamber technique and the soil N2O gradient technique; eddy covariance (EC) measured net ecosystem productivity (NEP); and energy requirements of fertilizer production, transport, and its aerial spreading. We found significant N2O losses in fertilized plots compared to a small uptake in nonfertilized plots. Chamber-measured N loss in the fertilized plots was about 16 kg N2O ha-1 in the first year, which is equivalent to 10 kg N ha-1 or 5% of the applied fertilizer N. Soil N2O emissions measured using the gradient technique, however, exceeded the chamber measurements by about 50%. We also compared a polymer-coated slow-release urea with regular urea and found that the former delayed N2O emissions but the year-end total loss was about the same as that from regular urea. Change in NEP due to fertilization was determined by relating annual NEP for the nonfertilized stand to environmental controls using an empirical and a process-based model. Annual NEP increased by 64%, from 326 g C m-2, calculated assuming that the stand was not fertilized, to the measured value of 535 g C m-2 with fertilization. At the end of the year, net change in GHG GWP was -2.28 t CO2 ha-1 compared to what it would have been without fertilization, thereby indicating favorable effect of fertilization even in the first year after fertilization with significant emissions of N2O.

  15. Spatially explicit estimates of N2 O emissions from croplands suggest climate mitigation opportunities from improved fertilizer management.

    PubMed

    Gerber, James S; Carlson, Kimberly M; Makowski, David; Mueller, Nathaniel D; Garcia de Cortazar-Atauri, Iñaki; Havlík, Petr; Herrero, Mario; Launay, Marie; O'Connell, Christine S; Smith, Pete; West, Paul C

    2016-10-01

    With increasing nitrogen (N) application to croplands required to support growing food demand, mitigating N2 O emissions from agricultural soils is a global challenge. National greenhouse gas emissions accounting typically estimates N2 O emissions at the country scale by aggregating all crops, under the assumption that N2 O emissions are linearly related to N application. However, field studies and meta-analyses indicate a nonlinear relationship, in which N2 O emissions are relatively greater at higher N application rates. Here, we apply a super-linear emissions response model to crop-specific, spatially explicit synthetic N fertilizer and manure N inputs to provide subnational accounting of global N2 O emissions from croplands. We estimate 0.66 Tg of N2 O-N direct global emissions circa 2000, with 50% of emissions concentrated in 13% of harvested area. Compared to estimates from the IPCC Tier 1 linear model, our updated N2 O emissions range from 20% to 40% lower throughout sub-Saharan Africa and Eastern Europe, to >120% greater in some Western European countries. At low N application rates, the weak nonlinear response of N2 O emissions suggests that relatively large increases in N fertilizer application would generate relatively small increases in N2 O emissions. As aggregated fertilizer data generate underestimation bias in nonlinear models, high-resolution N application data are critical to support accurate N2 O emissions estimates. PMID:27185532

  16. Modeling of N2O and NO emissions from soils in terrestrial ecosystems

    NASA Astrophysics Data System (ADS)

    Yang, X.; Jain, A.; Kotamarthi, V. R.

    2009-12-01

    Nitrous oxide (N2O) is not only one of the most important greenhouse gases,it is also involved in the depletion of stratospheric ozone. In the troposphere, Nitric Oxide (NO) is a short-lived chemically active gas that plays a critical role in ozone photochemistry. Soils under natural vegetation and agriculture are one of the main sources of N2O and NO through nitrification and denitrification processes. Current estimates of N2O and NO emissions on regional to global scales are based on the upscaling of limited measurements from specific measurement sites. These estimates have large uncertainties because of the heterogeneity of the soils and the seasonal and interannual variability in processes that control the nitrification/denitrification of soils. Here a geographically explicit process-based terrestrial carbon-nitrogen cycle component of the Integrated Science Assessment Model (ISAM) with a fully dynamic nitrogen cycle is used to estimate N2O and NO emissions from terrestrial ecosystems. In addition, the impacts of increasing CO2, climate change, N deposition, and land use change on the emission of N2O and NO from soil from 1765 to 2000 are investigated. The N cycle submodel of ISAM is calibrated and validated here with extensive field data from the Trace Gas Network (TRAGNET). TRAGNET includes N gas fluxes data from 29 sites in United States, which include grassland, forest, and cropland areas encompassing a gradient of climate conditions and soil properties. In comparison to field measurements, the model is able to capture the temporal trends and magnitude of the N2O emissions. The climate and soil moisture control on N2O and NO emissions are reflected in the simulations and correspond to observations. The observed elevated emissions of N2O during spring time at some of the sites however are not reproduced by the model. This could be due to the model’s inability to capture the dramatic changes of soil water content due to melting snow at these times. The

  17. Emissions of NO and N2O in wetland microcosms for swine wastewater treatment.

    PubMed

    Zhang, Shunan; Liu, Feng; Xiao, Runlin; Li, Yong; Zhou, Juan; Wu, Jinshui

    2015-12-01

    Nitric oxide (NO) and nitrous oxide (N2O) emitted from wetland systems contribute an important proportion to the global warming effect. In this study, four wetland microcosms vegetated with Myriophyllum elatinoides (WM), Alternanthera philoxeroides (WA), Eichhornia crassipes (WE), or without vegetation (NW) were compared to investigate the emissions of NO and N2O during nitrogen (N) removal process when treating swine wastewater. After 30-day incubation, TN removal rates of 96.4, 74.2, 97.2, and 47.3 % were observed for the WM, WA, WE, and NW microcosms, respectively. Yet, no significant difference was observed in WM and WE (p > 0.05). The average NO and N2O emissions in WE was significantly higher than those in WM, WA, and NW (p < 0.05). In addition, the emission of N2O in WE accounted for 2.10 % of initial TN load and 2.17 % of the total amount of TN removal, compared with less than 1 % in the other microcosms. These findings indicate that wetland vegetated with M. elatinoides may be an optimal system for swine wastewater treatment, based on its higher removal of N and lower emissions of NO and N2O. PMID:26289333

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

    PubMed Central

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

    2014-01-01

    Using static chambers and gas chromatography, nitrous oxide (N2O) fluxes from an apple orchard soil in the Bohai Bay region of China were measured from February 2010 to February 2011. In this study, two nitrogen (N) fertilizer treatments were designed—without (CK) or with (SN) synthetic N fertilizers (800 kg N ha−1). The annual cumulative N2O emissions from CK and SN were 34.6 ± 3.0 (mean ± standard error) and 44.3 ± 6.0 kg N2O–N ha−1, respectively. Such high emissions resulted from the intensive N fertilization in the experimental and previous years. The direct emission factor (EFd) of N2O induced by the applied synthetic N fertilizers was 1.2%. The EFd is within the range of previous studies carried out in other croplands, which suggests that it is reasonable to estimate regional N2O emissions from apple orchards using the EFd obtained in other croplands. In addition, significant positive correlations existed between N2O fluxes and soil temperatures or soil dissolved organic carbon contents. PMID:25050385

  19. Multivariate regulation of soil CO2 and N2 O pulse emissions from agricultural soils.

    PubMed

    Liang, Liyin L; Grantz, David A; Jenerette, G Darrel

    2016-03-01

    Climate and land-use models project increasing occurrence of high temperature and water deficit in both agricultural production systems and terrestrial ecosystems. Episodic soil wetting and subsequent drying may increase the occurrence and magnitude of pulsed biogeochemical activity, affecting carbon (C) and nitrogen (N) cycles and influencing greenhouse gas (GHG) emissions. In this study, we provide the first data to explore the responses of carbon dioxide (CO2 ) and nitrous oxide (N2 O) fluxes to (i) temperature, (ii) soil water content as percent water holding capacity (%WHC), (iii) substrate availability throughout, and (iv) multiple soil drying and rewetting (DW) events. Each of these factors and their interactions exerted effects on GHG emissions over a range of four (CO2 ) and six (N2 O) orders of magnitude. Maximal CO2 and N2 O fluxes were observed in environments combining intermediate %WHC, elevated temperature, and sufficient substrate availability. Amendments of C and N and their interactions significantly affected CO2 and N2 O fluxes and altered their temperature sensitivities (Q10 ) over successive DW cycles. C amendments significantly enhanced CO2 flux, reduced N2 O flux, and decreased the Q10 of both. N amendments had no effect on CO2 flux and increased N2 O flux, while significantly depressing the Q10 for CO2 , and having no effect on the Q10 for N2 O. The dynamics across DW cycles could be attributed to changes in soil microbial communities as the different responses to wetting events in specific group of microorganisms, to the altered substrate availabilities, or to both. The complex interactions among parameters influencing trace gas fluxes should be incorporated into next generation earth system models to improve estimation of GHG emissions. PMID:26470015

  20. Quantifying Uncertainties in N2O Emission Due to N Fertilizer Application in Cultivated Areas

    PubMed Central

    Philibert, Aurore; Loyce, Chantal; Makowski, David

    2012-01-01

    Nitrous oxide (N2O) is a greenhouse gas with a global warming potential approximately 298 times greater than that of CO2. In 2006, the Intergovernmental Panel on Climate Change (IPCC) estimated N2O emission due to synthetic and organic nitrogen (N) fertilization at 1% of applied N. We investigated the uncertainty on this estimated value, by fitting 13 different models to a published dataset including 985 N2O measurements. These models were characterized by (i) the presence or absence of the explanatory variable “applied N”, (ii) the function relating N2O emission to applied N (exponential or linear function), (iii) fixed or random background (i.e. in the absence of N application) N2O emission and (iv) fixed or random applied N effect. We calculated ranges of uncertainty on N2O emissions from a subset of these models, and compared them with the uncertainty ranges currently used in the IPCC-Tier 1 method. The exponential models outperformed the linear models, and models including one or two random effects outperformed those including fixed effects only. The use of an exponential function rather than a linear function has an important practical consequence: the emission factor is not constant and increases as a function of applied N. Emission factors estimated using the exponential function were lower than 1% when the amount of N applied was below 160 kg N ha−1. Our uncertainty analysis shows that the uncertainty range currently used by the IPCC-Tier 1 method could be reduced. PMID:23226430

  1. Evaluating Soil Oxygen as a Control on N2O Emissions from Ruminant Urine Patches under Different Irrigation Frequencies

    NASA Astrophysics Data System (ADS)

    Owens, J.; Clough, T. J.; Laubach, J.; Hunt, J.; Venterea, R. T.; Phillips, R. L.

    2015-12-01

    Urine patches from grazing ruminant animals are a significant source of nitrous oxide (N2O) emissions, and irrigation is increasingly used to improve forage quality and yield for grazing cattle. The objective of this study was to test whether irrigation frequency influenced N2O emissions from urine patches on a free-draining grazed pasture soil. It was hypothesized that greater irrigation frequency would increase soil moisture thereby lowering soil oxygen (O2), and that these O2-limited conditions would increase the potential for N2O to be reduced to nitrogen gas (N2), resulting in lower N2O emissions. A field trial tested the effects of two irrigation frequencies and urine deposition on N2O fluxes measured daily for 35 days. Denitrification potential measurements using the acetylene inhibition technique were completed to infer N2O/(N2O+N2) ratios, and soil O2 concentrations were measured continuously at three depths within the soil profile. While a more frequent irrigation treatment resulted in a lower N2O/(N2O+N2) ratio, this did not give rise to lower N2O emissions. Nitrous oxide fluxes were not influenced by irrigation frequency, and approximately 0.09% of the nitrogen applied as urine was emitted as N2O from both irrigation treatments. Neither N2O nor soil O2 varied with individual irrigation events. Soil O2 ranged from 17 to 20% expect following urine deposition, where it temporarily decreased to 13%. Soil O2 measurements failed to explain N2O emissions, but a relationship was derived between N2O fluxes and estimates of soil gas diffusivity (Dp/Do). This work is the first to show how soil O2 concentrations vary under a urine patch and under different irrigation treatments, and supports Dp/Do as robust predictor of N2O emissions in situ.

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

    PubMed

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

    2016-03-01

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

  3. Direct N2O emissions from rice paddy fields: Summary of available data

    NASA Astrophysics Data System (ADS)

    Akiyama, Hiroko; Yagi, Kazuyuki; Yan, Xiaoyuan

    2005-03-01

    Rice cultivation is an important anthropogenic source of atmospheric nitrous oxide (N2O) and methane. We compiled and analyzed data on N2O emissions from rice fields (113 measurements from 17 sites) reported in peer-reviewed journals. Mean N2O emission ± standard deviation and mean fertilizer-induced emission factor during the rice-cropping season were, respectively, 341 ± 474 g N ha-1 season-1 and 0.22 ± 0.24% for fertilized fields continuously flooded, 993 ± 1075 g N ha-1 season-1 and 0.37 ± 0.35% for fertilized fields with midseason drainage, and 667 ± 885 g N ha-1 season-1 and 0.31 ± 0.31% for all water regimes. The estimated whole-year background emission was 1820 g N ha-1 yr-1. A large uncertainty remains, especially for background emission because of limited data availability. Although midseason drainage generally reduces CH4 and increases N2O emissions, it may be an effective option for mitigating the net global warming potential of rice fields.

  4. Improving and disaggregating N2O emission factors for ruminant excreta on temperate pasture soils.

    PubMed

    Krol, D J; Carolan, R; Minet, E; McGeough, K L; Watson, C J; Forrestal, P J; Lanigan, G J; Richards, K G

    2016-10-15

    Cattle excreta deposited on grazed grasslands are a major source of the greenhouse gas (GHG) nitrous oxide (N2O). Currently, many countries use the IPCC default emission factor (EF) of 2% to estimate excreta-derived N2O emissions. However, emissions can vary greatly depending on the type of excreta (dung or urine), soil type and timing of application. Therefore three experiments were conducted to quantify excreta-derived N2O emissions and their associated EFs, and to assess the effect of soil type, season of application and type of excreta on the magnitude of losses. Cattle dung, urine and artificial urine treatments were applied in spring, summer and autumn to three temperate grassland sites with varying soil and weather conditions. Nitrous oxide emissions were measured from the three experiments over 12months to generate annual N2O emission factors. The EFs from urine treated soil was greater (0.30-4.81% for real urine and 0.13-3.82% for synthetic urine) when compared with dung (-0.02-1.48%) treatments. Nitrous oxide emissions were driven by environmental conditions and could be predicted by rainfall and temperature before, and soil moisture deficit after application; highlighting the potential for a decision support tool to reduce N2O emissions by modifying grazing management based on these parameters. Emission factors varied seasonally with the highest EFs in autumn and were also dependent on soil type, with the lowest EFs observed from well-drained and the highest from imperfectly drained soil. The EFs averaged 0.31 and 1.18% for cattle dung and urine, respectively, both of which were considerably lower than the IPCC default value of 2%. These results support both lowering and disaggregating EFs by excreta type. PMID:27300566

  5. General model for N2O and N2 gas emissions from soils due to dentrification

    NASA Astrophysics Data System (ADS)

    Del Grosso, S. J.; Parton, W. J.; Mosier, A. R.; Ojima, D. S.; Kulmala, A. E.; Phongpan, S.

    2000-12-01

    Observations of N gas loss from incubations of intact and disturbed soil cores were used to model N2O and N2 emissions from soil as a result of denitrification. The model assumes that denitrification rates are controlled by the availability in soil of NO3 (e- acceptor), labile C compounds (e- donor), and O2 (competing e- acceptor). Heterotrophic soil respiration is used as a proxy for labile C availability while O2 availability is a function of soil physical properties that influence gas diffusivity, soil WFPS, and O2 demand. The potential for O2 demand, as indicated by respiration rates, to contribute to soil anoxia varies inversely with a soil gas diffusivity coefficient which is regulated by soil porosity and pore size distribution. Model inputs include soil heterotrophic respiration rate, texture, NO3 concentration, and WFPS. The model selects the minimum of the NO3 and CO2 functions to establish a maximum potential denitrification rate for particular levels of e- acceptor and C substrate and accounts for limitation of O2 availability to estimate daily N2+N2O flux rates. The ratio of soil NO3 concentration to CO2 emission was found to reliably (r2=0.5) model the ratio of N2 to N2O gases emitted from the intact cores after accounting for differences in gas diffusivity among the soils. The output of the ratio function is combined with the estimate of total N gas flux rate to infer N2O emission. The model performed well when comparing observed and simulated values of N2O flux rates with the data used for model building (r2=0.50) and when comparing observed and simulated N2O+N2 gas emission rates from irrigated field soils used for model testing (r2=0.47).

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

    PubMed

    Liang, Hong; Yang, Jiaoling; Gao, Dawen

    2014-03-01

    Bionitrification is considered to be a potential source of nitrous oxide (N2O) emissions, which are produced as a by-product during the nitrogen removal process. To investigate the production of N2O during the process of nitrogen removal via nitrite, a granular sludge was studied using a lab-scale sequence batch reactor operated with real-time control. The total production of N2O generated during the nitrification and denitrification processes were 1.724 mg/L and 0.125 mg/L, respectively, demonstrating that N2O is produced during both processes, with the nitrification phase generating larger amount. In addition, due to the N2O-N mass/oxidized ammonia mass ratio, it can be concluded that nitrite accumulation has a positive influence on N2O emissions. Results obtained from PCR-DGGE analysis demonstrate that a specific Nitrosomonas microorganism is related to N2O emission. PMID:25079265

  7. Denitrification and N2O emission in an N-saturated subtropical forest catchment, southwest China

    NASA Astrophysics Data System (ADS)

    Zhu, Jing; Mulder, Jan; Dörsch, Peter

    2010-05-01

    Increasing anthropogenic emissions of nitrogen have resulted in locally high deposition rates of reactive nitrogen in China (30-73 kg N ha-1 a-1; Zhang. et al., 2008), primarily as NOx (from fossil fuel combustion) and NH3 (from fertilizer production and animal husbandry). Due to the subtropical, monsoonal climate with high soil temperature and moisture in summer, forests in south China may be expected to show high nitrification and denitrification rates, both of which can cause high N2O emissions. To estimate the N2O source strength and to investigate N-turnover processes relevant for N removal in subtropical forest, we investigated spatiotemporal patterns of N2O emission along a hydrological flowpath from July to November of 2009 in the TSP catchment (Tieshanping), situated close to Chongqing, one of the biggest cities in southwest China. Results from the first study year revealed high N cycling rates and N2O emissions during the wet season, (June to September). Surprisingly, soils on the hill slopes showed higher denitrification potentials and N2O emission rates than the wetter groundwater discharge zone at the bottom of the hill slopes. This was probably due to higher soil bulk density and less organic carbon content in the groundwater discharge zone. Highest denitrification potential were found in the O and A layer (< 5cm) of the hillslopes, suggesting that the organic carbon is the limiting factor for N-removal by denitrification in this ecosystem. High N-removal on the hill slopes was confirmed by decreasing NO3- concentrations along the flowpath during hydrologically stable conditions. However, high NO3- concentrations found in stream water during rain events suggest that the retention time of N in the catchment is too short to allow complete removal by denitrification. N2O emission fluxes dropped by two orders of magnitude in the beginning of the dry season, reflecting lower N input and removal rates during winter. Our results show that denitrification and

  8. Biofuel cropping system impacts on soil C, microbial communities and N2O emissions

    NASA Astrophysics Data System (ADS)

    McGowan, Andrew R.

    Substitution of cellulosic biofuel in place of gasoline or diesel could reduce greenhouse gas (GHG) emissions from transportation. However, emissions of nitrous oxide (N2O) and changes in soil organic carbon (SOC) could have a large impact on the GHG balance of cellulosic biofuel, thus there is a need to quantify these responses in cellulosic biofuel crops. The objectives of this study were to: (i) measure changes in yield, SOC and microbial communities in potential cellulosic biofuel cropping systems (ii) measure and characterize the temporal variation in N2O emissions from these systems (iii) characterize the yield and N2O response of switchgrass to N fertilizer and to estimate the costs of production. Sweet sorghum, photoperiod-sensitive sorghum, and miscanthus yielded the highest aboveground biomass (20-32 Mg ha-1). The perennial grasses sequestered SOC over 4 yrs, while SOC stocks did not change in the annual crops. Root stocks were 4-8 times higher in the perennial crops, suggesting greater belowground C inputs. Arbuscular mycorrhizal fungi (AMF) abundance and aggregate mean weight diameter were higher in the perennials. No consistent significant differences were found in N2O emissions between crops, though miscanthus tended to have the lowest emissions. Most N2O was emitted during large events of short duration (1-3 days) that occurred after high rainfall events with high soil NO3-. There was a weak relationship between IPCC Tier 1 N2O estimates and measured emissions, and the IPCC method tended to underestimate emissions. The response of N2O to N rate was nonlinear in 2 of 3 years. Fertilizer induced emission factor (EF) increased from 0.7% at 50 kg N ha-1 to 2.6% at 150 kg N ha-1. Switchgrass yields increased with N inputs up to 100-150 kg N ha-1, but the critical N level for maximum yields decreased each year, suggesting N was being applied in excess at higher N rates. Yield-scaled costs of production were minimized at 100 kg N ha-1 ($70.91 Mg-1

  9. New model for capturing the variations of fertilizer-induced emission factors of N2O

    NASA Astrophysics Data System (ADS)

    Zhou, Feng; Shang, Ziyin; Zeng, Zhenzhong; Piao, Shilong; Ciais, Philippe; Raymond, Peter A.; Wang, Xuhui; Wang, Rong; Chen, Minpeng; Yang, Changliang; Tao, Shu; Zhao, Yue; Meng, Qian; Gao, Shuoshuo; Mao, Qi

    2015-06-01

    Accumulating evidence indicates that N2O emission factors (EFs) vary with nitrogen additions and environmental variations. Yet the impact of the latter was often ignored by previous EF determinations. We developed piecewise statistical models (PMs) to explain how the N2O EFs in agricultural soils depend upon various predictors such as climate, soil attributes, and agricultural management. The PMs are derived from a new Bayesian Recursive Regression Tree algorithm. The PMs were applied to the case of EFs from agricultural soils in China, a country where large EF spatial gradients prevail. The results indicate substantial improvements of the PMs compared with other EF determinations. First, PMs are able to reproduce a larger fraction of the variability of observed EFs for upland grain crops (84%, n = 381) and paddy rice (91%, n = 161) as well as the ratio of EFs to nitrogen application rates (73%, n = 96). The superior predictive accuracy of PMs is further confirmed by evaluating their predictions against independent EF measurements (n = 285) from outside China. Results show that the PMs calibrated using Chinese data can explain 75% of the variance. Hence, the PMs could be reliable for upscaling of N2O EFs and fluxes for regions that have a phase space of predictors similar to China. Results from the validated models also suggest that climatic factors regulate the heterogeneity of EFs in China, explaining 69% and 85% of their variations for upland grain crops and paddy rice, respectively. The corresponding N2O EFs in 2008 are 0.84 ± 0.18% (as N2O-N emissions divided by the total N input) for upland grain crops and 0.65 ± 0.14% for paddy rice, the latter being twice as large as the Intergovernmental Panel on Climate Change Tier 1 defaults. Based upon these new estimates of EFs, we infer that only 22% of current arable land could achieve a potential reduction of N2O emission of 50%.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

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

    PubMed

    Melse, Roland W; Mosquera, Julio

    2014-01-01

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

  12. Nitrite intensity explains N management effects on N2O emissions in maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It is typically assumed that the dependence of nitrous oxide (N2O) emissions on soil nitrogen (N) availability is best quantified in terms of ammonium (NH4+) and/or nitrate (NO3-) concentrations. In contrast, nitrite (NO2-) is seldom measured separately from NO3- despite its role as a central substr...

  13. Management Practices to Mitigate N2O Emissions from Agricultural Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Results from 5 years of greenhouse gas measurements at an irrigated cropping systems site near Fort Collins, Colorado will be presented. In additions, data from the literature will be used to support our observations on nitrous oxide (N2O) emissions from these irrigated cropping systems. Observati...

  14. Comparison of simulated and observed N2O gas emission rates from bioenergy cropping systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide is the largest greenhouse gas source from crop systems. DAYCENT was used to compare N2O emissions from the following 3 bioenergy cropping systems: switchgrass, reed canarygrass, and a rotation of 3 yr corn, 1 yr soybeans, and 4 yr alfalfa. Although DAYCENT did not always capture the ob...

  15. Estimating Uncertainty in N2O Emissions from US Cropland Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A Monte Carlo analysis was combined with an empirically-based approach to quantify uncertainties in soil N2O emissions from US croplands estimated with the DAYCENT simulation model. Only a subset of croplands was simulated in the Monte Carlo analysis which was used to infer uncertainties across the ...

  16. Impact of oxygen injection on CH4 and N2O emissions from rising main sewers.

    PubMed

    Ganigué, Ramon; Yuan, Zhiguo

    2014-11-01

    Oxygen injection is a commonly used mitigation strategy for sulfide control in sewers. Methane, a potent greenhouse gas, is also produced in sewers. Oxygen injection may reduce methane generation/emission, but could potentially lead to N2O production due to the development of a nitrifying microbial community. The impact of oxygen dosing for sulfide control in sewers on CH4 and N2O production was assessed in this study in laboratory sewer reactors. Results showed that oxygen injection is able to reduce CH4 formation in sewers, although full control of CH4 was not achieved, likely due to partial oxygen penetration into sewer biofilm. The experimental results also revealed a nitrogen loss of around 5 mN/L. However, no significant N2O accumulation was detected. PMID:24975803

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

    PubMed

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

    2016-08-01

    Clark-Type nitrous oxide (N2O) sensors are routinely used to measure dissolved N2O concentrations in wastewater treatment plants (WWTPs), but have never before been applied to assess gas-phase N2O emissions in full-scale WWTPs. In this study, a full-scale N2O gas sensor was tested and validated for online gas measurements, and assessed with respect to its linearity, temperature dependence, signal saturation and drift prior to full-scale application. The sensor was linear at the concentrations tested (0-422.3, 0-50 and 0-10 ppmv N2O) and had a linear response up to 2750 ppmv N2O. An exponential correlation between temperature and sensor signal was described and predicted using a double exponential equation while the drift did not have a significant influence on the signal. The N2O gas sensor was used for online N2O monitoring in a full-scale sequencing batch reactor (SBR) treating domestic wastewater and results were compared with those obtained by a commercial online gas analyser. Emissions were successfully described by the sensor, being even more accurate than the values given by the commercial analyser at N2O concentrations above 500 ppmv. Data from this gas N2O sensor was also used to validate two models to predict N2O emissions from dissolved N2O measurements, one based on oxygen transfer rate and the other based on superficial velocity of the gas bubble. Using the first model, predictions for N2O emissions agreed by 98.7% with the measured by the gas sensor, while 87.0% similarity was obtained with the second model. This is the first study showing a reliable estimation of gas emissions based on dissolved N2O online data in a full-scale wastewater treatment facility. PMID:27155989

  18. [Estimation of N2O Emission from Anhui Croplands by Using a Regional Nitrogen Cycling Model IAP-N].

    PubMed

    Han, Yun-fang; Han, Sheng-hui; Yan, Ping

    2015-07-01

    N2O emissions from seven categories of Anhui croplands in 2011 were estimated by using a regional nitrogen cycling model IAP-N. The required statistical data were from each city's statistical yearbook in Anhui Province. The emission factors were from the published field data. The results showed that total N2O emissions from Anhui croplands in 2011 were 35. 1 thousand ton, in which direct and indirect N2O emissions were, respectively, 27. 6 thousand ton and 6. 6 thousand ton, and N2O emission from residues/straws burning in the field was 800 ton. Huaibei Plain (Region I) and Jianghuai Hilly (Region II) were the main contribution regions in Anhui, accounting for 41% and 35% of its regional total N2O emissions, respectively. The most important source for direct N2O emission is the year round upland fields with 74% contribution of the province total direct N2O emission. The second important source in Region II and Region III is upland cropping season of the rotation fields with rice and upland-crops, accounting for 19% and 14% , respectively. While in Region IV, the second direct N2O emission sources are tea gardens and orchards, accounting for 22%. About two-thirds of the indirect N2O were from atmospheric nitrogen deposition. The results can provide a scientific basis for policy makers to make agricultural soils GHG mitigation measures in Anhui Province, such as reasonable use of fertilizers. PMID:26489304

  19. [Nitrogen removal and N2O emission characteristics during the shortcut simultaneous nitrification and denitrification process].

    PubMed

    Liang, Xiao-ling; Li, Ping; Wu, Jin-hua; Wang, Xiang-de

    2013-05-01

    Complete simultaneous nitrification and denitrification (SND) was achieved in an air lift circulation bioreactor. Based on this condition, the system could be switched to shortcut SND as the free ammonia (FA) concentration was increased with higher influent pH. The nitrogen removal and N2O emission characteristics of the shortcut SND process were investigated and those of the complete SND process were also observed as control. In the shortcut SND process, the average total nitrogen removal and average SND efficiency reached 71.9% and 80.9%, which was 18.0 and 16.8 percents higher than those in the complete SND process, respectively. In addition, the total nitrogen removal rate in the shortcut SND process was 0.11 mg x (L x min)(-1), 1.4 times as high as that in the complete SND process. Although higher nitrogen removal efficiency was obtained in the shortcut SND process, the mean N2O conversion rate reached 57.1% and the average N2O accumulated emission amount was approximately 4 times higher than that in the complete SND process. The results also indicated that the increase of NO2- -N concentration in the reactor should be responsible for the remarkable enhancement of N2O emission. PMID:23914537

  20. Measurements of N2O emissions from different vegetable fields on the North China Plain

    NASA Astrophysics Data System (ADS)

    Diao, Tiantian; Xie, Liyong; Guo, Liping; Yan, Hongliang; Lin, Miao; Zhang, He; Lin, Jia; Lin, Erda

    2013-06-01

    Few studies have measured the N2O emission fluxes from vegetable fields. In order to identify the characteristics and the influencing factors of N2O emissions from different vegetable fields, we measured N2O emissions for a full year from four typical fields, including an open-ground vegetable field that has produced vegetables for over 20 years (OV20), a recently developed open-ground vegetable field that was converted from a maize field three years earlier (OV3), a recently developed greenhouse vegetable field that was converted from a maize field 3 years earlier (GV3) and a typical local maize field (Maize). Four different fertilization treatments were set additionally in the recently developed open-ground vegetable field. These were: no fertilizer or manure (OV3_CK), manure only (OV3_M) and the combination of manure with different rates of chemical fertilizer application (OV3_MF1 and OV3_MF3). The results showed that N2O emission fluxes fluctuated between 0.3 ± 0.1 and 912.4 ± 80.0 mg N2O-N m-2 h-1 with the highest emission peak occurring after fertilization followed by irrigation. Nitrogen application explained 64.6-84.5% of the N2O emission in the vegetable fields. The magnitude of the emission peaks depended on the nitrogen application rate and the duration of the emission peaks was mainly associated with soil temperature when appropriate irrigation was given after fertilization. The N2O emission peaks occurred later and lasted for a longer period when the soil temperature was <24 °C in May. However, emission peaks occurred earlier and lasted for a shorter period when the soil temperature was around 25-33 °C from June to August. The annual N2O emissions from the fertilized vegetable fields were 1.68-2.38 times higher than that from the maize field, which had an emission value of 2.88 ± 0.10 kg N ha-1 a-1. The N2O emission factor (EF) of manure nitrogen was 0.07% over the whole year, but was 0.11% and 0.02% in the spring cucumber season and the autumn

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    PubMed

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

    2014-01-01

    Recent studies have indicated that the emissions of nitrous oxide, N2O, constitute a major part of the carbon footprint of wastewater treatment plants (WWTPs). Denitrification occurring in the secondary clarifier basins has been observed by many researchers, but until now N2O emissions from secondary clarifiers have not been widely reported. The objective of this study was to measure the N2O emissions from secondary clarifiers and weigh the portion they could represent of the overall emissions at WWTPs. Online measurements over several days were carried out at four different municipal WWTPs in Finland in cold weather conditions (March) and in warm weather conditions (June-July). An attempt was made to define the conditions in which N2O emissions from secondary clarifiers may occur. It was evidenced that large amounts of N2O can be emitted from the secondary clarifiers, and that the emissions have long-term variation. It was assumed that part of the N2O released in secondary clarification was originally formed in the activated sludge basin. The emissions from secondary clarification thus seem to be dependent on conditions of the nitrification and denitrification accomplished in the denitrification-nitrification process and on the amount of sludge stored in the secondary clarifiers. PMID:25116504

  3. N2O Emissions in Southeastern Amazonia: The Effect of Agricultural Intensification

    NASA Astrophysics Data System (ADS)

    O'Connell, C.; Brando, P. M.; Cerri, C. E.; Coe, M. T.; Davidson, E. A.; Galford, G. L.; Macedo, M.; Neill, C.; Venterea, R. T.

    2014-12-01

    The Amazon is not only an exceptionally biodiverse and carbon-rich tract of tropical forest, it is also a case study in land use change. Over the last 30 years, Amazonia has been home to extraordinary growth in agricultural production, in part from agricultural expansion, but also due to more intense management on Amazonia's existing croplands. We use a year-long campaign and approximately 500 field chamber measurements to estimate how cropland intensification in Mato Grosso, Brazil affects the emission of nitrous oxide (N2O) and soil N dynamics. In this system, soybean cropland intensification occurs when double cropping is introduced, in which maize is planted directly after soybean harvest and fertilized twice with inorganic N. We find that dry season N2O emissions in single-cropped (soybean only) fields, double-cropped (soybean/maize) fields and reference tropical forest are uniformly near zero, or ~0-0.5 ngN/cm^2/hr. Surprisingly, wet season emissions rates remain low as well, between 1-4 ngN/cm^2/hr, for both cropland types and reference forest. By contrast, isolated post-fertilization spikes in N2O emissions are large, with a maximum increase of ~800% and a mean increase of ~400%, though these flux increases resolve rapidly and rates return to their low baseline within days. Finally, we explore the role that soil moisture, soil N availability, and soil C availability play in regulating N2O fluxes in reference forest, soybean fields and intensified soybean-maize fields. Open questions surround how the Amazon's land resources can be leveraged to increase agricultural production at the least harm to the environment. Here, we quantify the consequences of land use change on N2O, a powerful greenhouse gas, in a critical ecosystem undergoing novel agricultural intensification. These results may inform both greenhouse gas accounting and our understanding of the effects of Amazonia's changing agricultural landscape on the nitrogen cycle.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  5. Effect of anoxic/aerobic phase fraction on N2O emission in a sequencing batch reactor under low temperature.

    PubMed

    Hu, Zhen; Zhang, Jian; Xie, Huijun; Li, Shanping; Wang, Jinhe; Zhang, Tingting

    2011-05-01

    Laboratory scale anoxic/aerobic sequencing batch reactor (A/O SBR) was operated around 15°C to evaluate the effect of anoxic/aerobic phase fraction (PF) on N(2)O emission. The ammonia removal exhibited a decrease trend with the increase of PF, while the highest total nitrogen removal was achieved at PF=0.5. Almost all the N(2)O was emitted during the aerobic phase, despite of the PF value. However, the net emission of N(2)O was affected by PF. Under the premise of completely aerobic nitrification, the lowest N(2)O emission was achieved at PF=0.5, with a N(2)O-N conversion rate of 9.8%. At lower PF (PF=0.2), N(2)O emission was stimulated by residual nitrite caused by uncompleted denitrification during the anoxic phase. On the other hand, the exhaustion of the easily degradable carbon was the major cause for the high N(2)O emission at higher PF (PF=0.5). The N(2)O emission increased with the decreasing temperature. The time-weighted N(2)O emission quantity at 15°C was 2.9 times higher than that at 25°C. PMID:21035326

  6. Response of N2O emissions to elevated water depth regulation: comparison of rhizosphere versus non-rhizosphere of Phragmites australis in a field-scale study.

    PubMed

    Gu, Xiao-Zhi; Chen, Kai-Ning; Wang, Zhao-de

    2016-03-01

    Emissions of nitrous oxide (N2O) from wetland ecosystems are globally significant and have recently received increased attention. However, relatively few direct studies of these emissions in response to water depth-related changes in sediment ecosystems have been conducted, despite the likely role they play as hotspots of N2O production. We investigated depth-related differential responses of the dissolved inorganic nitrogen distribution in Phragmites australis (Cav.) Trin. ex Steud. rhizosphere versus non-rhizosphere sediments to determine if they accelerated N2O emissions and the release of inorganic nitrogen. Changes in static water depth and P. australis growth both had the potential to disrupt the distribution of porewater dissolved NH4 (+), NO3 (-), and NO2 (-) in profiles, and NO3 (-) had strong surface aggregation tendency and decreased significantly with depth. Conversely, the highest NO2 (-) contents were observed in deep water and the lowest in shallow water in the P. australis rhizosphere. When compared with NO3 (-), NH4 (+), and NO2 (-), fluxes from the rhizosphere were more sensitive to the effects of water depth, and both fluxes increased significantly at a depth of more than 1 m. Similarly, N2O emissions were obviously accelerated with increasing depth, although those from the rhizosphere were more readily controlled by P. australis. Pearson's correlation analysis showed that water depth was significantly related to N2O emission and NO2 (-) fluxes, and N2O emissions were also strongly dependent on NO2 (-) fluxes (r = 0.491, p < 0.05). The results presented herein provide new insights into inorganic nitrogen biogeochemical cycles in freshwater sediment ecosystems. PMID:26561329

  7. Comparison of N2O Emissions from Soils at Three Temperate Agricultural Sites

    NASA Technical Reports Server (NTRS)

    Frolking, S. E.; Moiser, A. R.; Ojima, D. S.; Li, C.; Parton, W. J.; Potter, C. S.; Priesack, E.; Stenger, R.; Haberbosch, C.; Dorsch, P.; Peterson, David L. (Technical Monitor)

    1997-01-01

    Nitrous oxide (N2O) flux simulations by four models were compared with year-round field measurements from five temperate agricultural sites in three countries. The field sites included an unfertilized, semi-arid rangeland with low N2O fluxes in eastern Colorado, USA; two fertilizer treatments (urea and nitrate) on a fertilized grass ley cut for silage in Scotland; and two fertilized, cultivated crop fields in Germany where N2O loss during the winter was quite high. The models used were daily trace gas versions of the CENTURY model, DNDC, ExpertN, and the NASA-Ames version of the CASA model. These models included similar components (soil physics, decomposition, plant growth, and nitrogen transformations), but in some cases used very different algorithms for these processes. All models generated similar results for the general cycling of nitrogen through the agro-ecosystems, but simulated nitrogen trace gas fluxes were quite different. In most cases the simulated N20 fluxes were within a factor of about 2 of the observed annual fluxes, but even when models produced similar N2O fluxes they often produced very different estimates of gaseous N loss as nitric oxide (NO), dinitrogen (N2), and ammonia (NH3). Accurate simulation of soil moisture appears to be a key requirement for reliable simulation of N2O emissions. All models simulated the general pattern of low background fluxes with high fluxes following fertilization at the Scottish sites, but they could not (or were not designed to) accurately capture the observed effects of different fertilizer types on N2O flux. None of the models were able to reliably generate large pulses of N2O during brief winter thaws that were observed at the two German sites. All models except DNDC simulated very low N2O fluxes for the dry site in Colorado. The US Trace Gas Network (TRAGNET) has provided a mechanism for this model and site intercomparison. Additional intercomparisons are needed with these and other models and additional data

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  9. NO versus N2O emissions from an NH4(+)-amended Bermuda grass pasture

    NASA Technical Reports Server (NTRS)

    Hutchinson, G. L.; Brams, E. A.

    1992-01-01

    An enclosure technique is used to monitor soil NO and N2O emissions during early summer regrowth of Bermuda grass (Cynodon dactylon) on sandy loam in a humid, subtropical region of southern Texas. The evolution of both gases was substantially higher from plots harvested at the beginning of the experiment and fertilized five days later with 52 kg N/ha as (NH4)2SO4 than from plots not harvested or fertilized. Emission of NO, but not N2O, was stimulated by clipping and removing the grass, probably because eliminating the shading provided by the dense grass canopy changed these plots from cooler to warmer than unharvested plots, thereby stimulating the activity of soil microorganisms responsible for NO production. Neither gas flux was significantly affected by application of N until the next rainfall dissolved and moved the surface-applied fertilizer into the soil. Immediately thereafter, emissions of NO and N2O increased dramatically to peaks of 160 and 12 g N/ha/d, respectively, and then declined at rates that closely parallel the nitrification rate of added NH4(+), indicating that the gases resulted from the activity of nitrifying microorganisms, rather than denitrifiers. Nitric oxide emissions during the nine-week measurement period averaged 7.2 times greater than N2O emissions and accounted for 3.2 percent of the added N. The data indicate that humid, subtropical grasslands, which not only have large geographical extent but also have been subject to intense anthropogenic disturbance, contribute significantly to the global atmospheric NO(x) budget.

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

    NASA Astrophysics Data System (ADS)

    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 < 0.01), 3.56 ( p < 0.01), and 2.12 ( p < 0.01) from the soil samples preincubated with 5% CH 4 for three months when compared with the control, respectively. Among the three selected 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 < 0.001). N 2O fluxes were also elevated by the increase of the CH 4 emissions with 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 < 0.01) from sandy soil-covered landfill site, which was 72% ( p < 0.05) and 173% ( p < 0.01) lower than the other two clay soil covered 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.

  11. Aerobic N2O emission for activated sludge acclimated under different aeration rates in the multiple anoxic and aerobic process.

    PubMed

    Wang, Huoqing; Guan, Yuntao; Pan, Min; Wu, Guangxue

    2016-05-01

    Nitrous oxide (N2O) is a potent greenhouse gas that can be emitted during biological nitrogen removal. N2O emission was examined in a multiple anoxic and aerobic process at the aeration rates of 600mL/min sequencing batch reactor (SBRL) and 1200mL/min (SBRH). The nitrogen removal percentage was 89% in SBRL and 71% in SBRH, respectively. N2O emission mainly occurred during the aerobic phase, and the N2O emission factor was 10.1% in SBRL and 2.3% in SBRH, respectively. In all batch experiments, the N2O emission potential was high in SBRL compared with SBRH. In SBRL, with increasing aeration rates, the N2O emission factor decreased during nitrification, while it increased during denitrification and simultaneous nitrification and denitrification (SND). By contrast, in SBRH the N2O emission factor during nitrification, denitrification and SND was relatively low and changed little with increasing aeration rates. The microbial competition affected the N2O emission during biological nitrogen removal. PMID:27155411

  12. Comparison of APSIM and DNDC simulations of nitrogen transformations and N2O emissions.

    PubMed

    Vogeler, I; Giltrap, D; Cichota, R

    2013-11-01

    Various models have been developed to better understand nitrogen (N) cycling in soils, which is governed by a complex interaction of physical, chemical and biological factors. Two process-based models, the Agricultural Production Systems sIMulator (APSIM) and DeNitrification DeComposition (DNDC), were used to simulate nitrification, denitrification and nitrous oxide (N2O) emissions from soils following N input from either fertiliser or excreta deposition. The effect of environmental conditions on N transformations as simulated by the two different models was compared. Temperature had a larger effect in APSIM on nitrification, whereas in DNDC, water content produced a larger response. In contrast, simulated denitrification showed a larger response to temperature and also organic carbon content in DNDC. And while denitrification in DNDC is triggered by rainfall ≥5mm/h, in APSIM, the driving factor is soil water content, with a trigger point at water content at field capacity. The two models also showed different responses to N load, with nearly linearly increasing N2O emission rates with N load simulated by DNDC, and a lower rate by APSIM. Increasing rainfall intensity decreased APSIM-simulated N2O emissions but increased those simulated by DNDC. PMID:23036495

  13. Assessment of N2O emission from a photobioreactor treating ammonia-rich swine wastewater digestate.

    PubMed

    Mezzari, Melissa P; da Silva, Márcio L B; Nicoloso, Rodrigo S; Ibelli, Adriana M G; Bortoli, Marcelo; Viancelli, Aline; Soares, Hugo M

    2013-12-01

    This study investigated the interactions between naturally occurring bacteria and the microalgae Chlorella vulgaris within a lab scale photobioreactor treating ammonia-rich swine wastewater digestate effluent. Nitrification and denitrification were assessed by targeting ammonia monoxygenases (amoA), nitrate (narG), nitrite (nirS), nitric oxide (norB) and nitrous oxide (nosZ) reductases genes. Oxygen produced from microalgae photosynthesis stimulated nitrification. Under limiting carbon availability (i.e., <1.44 for mg TOC/mg NO2-N and 1.72 for mg TOC/mg NO3-N), incomplete denitrification led to accumulation of NO2 and NO3. Significant N2O emission (up to 118 μg N2O-N) was linked to NO2 metabolism in Chlorella. The addition of acetate as external carbon source recovered heterotrophic denitrification activity suppressing N2O emission. Effluent methane concentrations trapped within photobioreactor was removed concomitantly with ammonia. Overall, closed photobioreactors can be built to effectively remove nitrogen and mitigate simultaneously greenhouse gases emissions that would occur otherwise in open microalgae-based wastewater treatment systems. PMID:24128394

  14. NO and N2O emissions from agricultural fields in the North China Plain: Origination and mitigation.

    PubMed

    Zhang, Yuanyuan; Mu, Yujing; Zhou, Yizhen; Tian, Di; Liu, Junfeng; Zhang, Chenglong

    2016-05-01

    Agricultural soil has been recognized as a major source of atmospheric NO and N2O emissions which have important impacts on regional and global environments. Here we comparably investigated the effects of ammonium, nitrate fertilizers and nitrification inhibitor dicyandiamide (DCD) addition on NO and N2O emissions from the agricultural soil in the North China Plain (NCP). Compared with the ammonium fertilizer application, the reductions of NO emissions caused by nitrate fertilizer and DCD addition were 100% and 93%, and of N2O emissions were 54% and 74%, respectively. Remarkable reductions of NO and N2O emissions were also observed from five different agricultural soils in the NCP by replacing ammonium with nitrate fertilizer, indicating that nitrification is the predominant process for the emissions of NO and N2O from the soils in the vast area of NCP. NO emission peaks were found to be several days later than N2O peaks after the application of ammonium fertilizer and flooding irrigation, implying that most of NO initially produced via nitrification process might be fast reduced to N2O under the high soil moisture condition. Interestingly, the relative contribution of denitrification to N2O emission showed obviously time-dependent, e.g., evident N2O emission caused by the application of nitrate was only observed after the basal fertilization for the maize and the topdressing for the wheat. Replacing ammonium with nitrate fertilizer and mixing with the nitrification inhibitor are verified to be effective measures for mitigating NO and N2O emissions from arable soils in the NCP. PMID:26874775

  15. Winter N2O emission rate and its production rate in soil underlying the snowpack in a subboreal region, Japan

    NASA Astrophysics Data System (ADS)

    Kim, Yongwon; Tanaka, Noriyuki

    2002-10-01

    Concentrations of N2O and 222Rn were observed in the snowpack and the soil from the subboreal region of Japan during the winter of 1996 to 1997. These observations were made to validate 222Rn as a proxy for temporal variation of N2O diffusivity within a snowpack having many ice lenses in order to estimate N2O emission through the snowpack to the atmosphere, to make a better evaluation of soil N2O production rate underlying the snowpack using 222Rn mixing rate in soil, and to clarify the factors influencing N2O flux and the production rate in subboreal ecosystems. Using a one-dimensional vertical diffusion model under a nonsteady state condition, N2O flux markedly increased from 0.0034 to 18 μg N/m2/d with snow depth of an average of 4.1 ± 4.4 μg N/m2/d (1σ). The wide range of low N2O flux results from the surface soil freezing in early winter and the existence of multilayered ice lenses within the snowpack throughout the winter. When the 222Rn mixing rate varied from 4.0 cm/d to 16 cm/d, the soil N2O production rate underlying the snowpack significantly increased -3.4 to 48 mg N/m3/h with an average of 22 ± 15 mg N/m3/h (1σ). The soil temperature had a remarkably positive correlation with snow depth (R = 0.85). Therefore it can be concluded that the deeper snow cover does not prevent but does promote the production of N2O in soil and its emission to the atmosphere in the subboreal region of Japan. Although we estimated some N2O flux through the snowpack during the winter, based on the results presented here and published elsewhere, the winter regional N2O emission rate through the snowpack is estimated to be 0.07 Tg N/season, which corresponds to 30% of the annual N2O emission in the boreal ecosystem in the Northern Hemisphere. This unambiguously suggests that further data on the winter N2O fluxes are needed to assess the contribution of natural soils to the regional N2O budget and to evaluate impacts of the seasonality of the N2O emission rate on

  16. High-Resolution Upscaling of Closed Chamber Fluxes for N2o Emissions from China's Agricultural Soils

    NASA Astrophysics Data System (ADS)

    Zhou, F.; Shang, Z.; Ciais, P.; Piao, S.; Raymond, P. A.; Tao, S.; Zeng, Z.

    2014-12-01

    Moving from local toward global N2O emissions brings up numerous issues related to data processing, aggregation, tradeoffs between model quality and data quality, and prioritization of data collection and/or compilation efforts. We studied these issues in the context of modelling China's N2O emissions from agricultural soils. We developed a spatially-explicit model (PKU-N2O-Agr model) for high-resolution mapping of N2O emissions based on the idea of Hole-in-the-Pipe Model. We collected 709 site-year records (504 for upland and 205 for paddy) at 106 experimental sites across China from 1994 to 2013 and calibrated the observed N2O flux by using the Bayesian Recursive Regression Tree algorithm. The calibrated PKU-N2O-Agr model is applied to simulate China's N2O emissions from upland and paddy cropland at 1-km spatial resolution and to examine the variable importance and sensitivity for N2O emissions as well as scaling dependence of the effect-response relationships. The N2O emissions in 2008 are 615 GgN2O/yr and ~25% lower than PKU-N2O and EDGAR v4.2 global product sampled over China. The average coefficients of determination between observed and simulated results were 0.91 for upland and 0.92 for paddy cropland, which indicate the using a simplified data-driven approach with data of high resolution could produce accurate and reliable results. Emission factors (considering background emissions) for paddy and upland soils are 0.6% and 0.8% of N inputs, which are 2 times of IPCC default but half of the mean of observations, respectively. SOC is the most important for capturing the variability of N2O emissions from upland, whereas N inflow is the critical factor for paddy cropland. Different with previous works, the marginal sensitivities of environmental factors on agricultural N2O emissions are calculated, which is of great use for verifying process-based simulation model when being applied in China (e.g., DNDC). Both critical factors and the effect

  17. Verifying the UK N_{2}O emission inventory with tall tower measurements

    NASA Astrophysics Data System (ADS)

    Carnell, Ed; Meneguz, Elena; Skiba, Ute; Misselbrook, Tom; Cardenas, Laura; Arnold, Tim; Manning, Alistair; Dragosits, Ulli

    2016-04-01

    Nitrous oxide (N2O) is a key greenhouse gas (GHG), with a global warming potential ˜300 times greater than that of CO2. N2O is emitted from a variety of sources, predominantly from agriculture. Annual UK emission estimates are reported, to comply with government commitments under the United Nations Framework Convention on Climate Change (UNFCCC). The UK N2O inventory follows internationally agreed protocols and emission estimates are derived by applying emission factors to estimates of (anthropogenic) emission sources. This approach is useful for comparing anthropogenic emissions from different countries, but does not capture regional differences and inter-annual variability associated with environmental factors (such as climate and soils) and agricultural management. In recent years, the UK inventory approach has been refined to include regional information into its emissions estimates (e.g. agricultural management data), in an attempt to reduce uncertainty. This study attempts to assess the difference between current published inventory methodology (default IPCC methodology) and a revised approach, which incorporates the latest thinking, using data from recent work. For 2013, emission estimates made using the revised approach were 30 % lower than those made using default IPCC methodology, due to the use of lower emission factors suggested by recent projects (www.ghgplatform.org.uk, Defra projects: AC0116, AC0213 and MinNO). The 2013 emissions estimates were disaggregated on a monthly basis using agricultural management (e.g. sowing dates), climate data and soil properties. The temporally disaggregated emission maps were used as input to the Met Office atmospheric dispersion model NAME, for comparison with measured N2O concentrations, at three observation stations (Tacolneston, E England; Ridge Hill, W England; Mace Head, W Ireland) in the UK DECC network (Deriving Emissions linked to Climate Change). The Mace Head site, situated on the west coast of Ireland, was

  18. N2O emissions due to nitrogen fertilizer applications in two regions of sugarcane cultivation in Brazil

    NASA Astrophysics Data System (ADS)

    Signor, D.; Cerri, C. E. P.; Conant, R.

    2013-03-01

    Among the main greenhouse gases (CO2, CH4 and N2O), N2O has the highest global warming potential. N2O emission is mainly connected to agricultural activities, increasing as nitrogen concentrations increase in the soil with nitrogen fertilizer application. We evaluated N2O emissions due to application of increasing doses of ammonium nitrate and urea in two sugarcane fields in the mid-southern region of Brazil: Piracicaba (São Paulo state) and Goianésia (Goiás state). In Piracicaba, N2O emissions exponentially increased with increasing N doses and were similar for urea and ammonium nitrate up to a dose of 107.9 kg ha-1 of N. From there on, emissions exponentially increased for ammonium nitrate, whereas for urea they stabilized. In Goianésia, N2O emissions were lower, although the behavior was similar to that at the Piracicaba site. Ammonium nitrate emissions increased linearly with N dose and urea emissions were adjusted to a quadratic equation with a maximum amount of 113.9 kg N ha-1. This first effort to measure fertilizer induced emissions in Brazilian sugarcane production not only helps to elucidate the behavior of N2O emissions promoted by different N sources frequently used in Brazilian sugarcane fields but also can be useful for future Brazilian ethanol carbon footprint studies.

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

    PubMed

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

    2014-06-24

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

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

    NASA Astrophysics Data System (ADS)

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

    2004-12-01

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

  1. Budget of N2O emissions at the watershed scale: role of land cover and topography (the Orgeval basin, France)

    NASA Astrophysics Data System (ADS)

    Vilain, G.; Garnier, J.; Passy, P.; Silvestre, M.; Billen, G.

    2011-11-01

    Agricultural basins are the major source of N2O emissions, with arable land accounting for half of the biogenic emissions worldwide. Moreover, N2O emission strongly depends on the position of agricultural land in relation with topographical gradients, as footslope soils are often more prone to denitrification. The estimation of land surface area occupied by agricultural soils depends on the available spatial input information and resolution. Surface areas of grassland, forest and arable lands were estimated for the Orgeval sub-basin using two cover representations: the pan European CORINE Land Cover 2006 database (CLC 2006) and a combination of two databases produced by the Institut d'Aménagement et d'Urbanisme de la Région d'Île-de-France (IAU IDF), the MOS (Mode d'Occupation des Sols) combined with the Ecomos 2000, a land-use classification. In this study we have analyzed how different land-cover representations influence and introduce errors into the results of regional N2O emissions inventories. A further introduction of the topography concept was used to better identify the critical zones for N2O emissions, a crucial issue to better adapt the strategies of N2O emissions mitigation. Overall, we observed that a refinement of the land-cover database led to a 5% decrease in the estimation of N2O emissions, while the integration of the topography decreased the estimation of N2O emissions up to 25%.

  2. Budget of N2O emissions at the watershed scale: role of land cover and topography (the Orgeval basin, France)

    NASA Astrophysics Data System (ADS)

    Vilain, G.; Garnier, J.; Passy, P.; Silvestre, M.; Billen, G.

    2012-03-01

    Agricultural basins are the major source of N2O emissions, with arable land accounting for half of the biogenic emissions worldwide. Moreover, N2O emission strongly depends on the position of agricultural land in relation with topographical gradients, as footslope soils are often more prone to denitrification. The estimation of land surface area occupied by agricultural soils depends on the available spatial input information and resolution. Surface areas of grassland, forest and arable lands were estimated for the Orgeval sub-basin using two cover representations: the pan European CORINE Land Cover 2006 database (CLC 2006) and a combination of two databases produced by the IAU IDF (Institut d'Aménagement et d'Urbanisme de la Région d'Île-de-France), the MOS (Mode d'Occupation des Sols) combined with the ECOMOS 2000 (a land-use classification). In this study, we have analyzed how different land-cover representations influence and introduce errors into the results of regional N2O emissions inventories. A further introduction of the topography concept was used to better identify the critical zones for N2O emissions, a crucial issue to better adapt the strategies of N2O emissions mitigation. Overall, we observed that a refinement of the land-cover database led to a 5 % decrease in the estimation of N2O emissions, while the integration of the topography decreased the estimation of N2O emissions up to 25 %.

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

    PubMed

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

    2013-01-01

    No-tillage and reduced tillage (NT/RT) management practices are being promoted in agroecosystems to reduce erosion, sequester additional soil C and reduce production costs. The impact of NT/RT on N2 O emissions, however, has been variable with both increases and decreases in emissions reported. Herein, we quantitatively synthesize studies on the short- and long-term impact of NT/RT on N2 O emissions in humid and dry climatic zones with emissions expressed on both an area- and crop yield-scaled basis. A meta-analysis was conducted on 239 direct comparisons between conventional tillage (CT) and NT/RT. In contrast to earlier studies, averaged across all comparisons, NT/RT did not alter N2 O emissions compared with CT. However, NT/RT significantly reduced N2 O emissions in experiments >10 years, especially in dry climates. No significant correlation was found between soil texture and the effect of NT/RT on N2 O emissions. When fertilizer-N was placed at ≥5 cm depth, NT/RT significantly reduced area-scaled N2 O emissions, in particular under humid climatic conditions. Compared to CT under dry climatic conditions, yield-scaled N2 O increased significantly (57%) when NT/RT was implemented <10 years, but decreased significantly (27%) after ≥10 years of NT/RT. There was a significant decrease in yield-scaled N2 O emissions in humid climates when fertilizer-N was placed at ≥5 cm depth. Therefore, in humid climates, deep placement of fertilizer-N is recommended when implementing NT/RT. In addition, NT/RT practices need to be sustained for a prolonged time, particularly in dry climates, to become an effective mitigation strategy for reducing N2 O emissions. PMID:23504719

  4. N2O and NO emissions during autotrophic nitrogen removal in a granular sludge reactor--a simulation study.

    PubMed

    Van Hulle, S W H; Callens, J; Mampaey, K E; van Loosdrecht, M C M; Volcke, E I P

    2012-01-01

    This contribution deals with NO and N2O emissions during autotrophic nitrogen removal in a granular sludge reactor. Two possible model scenarios describing this emission by ammonium- oxidizing biomass have been compared in a simulation study of a granular sludge reactor for one-stage partial nitritation--Anammox. No significant difference between these two scenarios was noticed. The influence of the bulk oxygen concentration, granule size, reactor temperature and ammonium load on the NO and N2O emissions has been assessed. The simulation results indicate that emission maxima of NO and N2O coincide with the region for optimal Anammox conversion. Also, most of the NO and N2O are present in the off-gas, owing to the limited solubility of both gases. The size of granules needs to be large enough not to limit optimal Anammox activity, but not too large as this implies an elevated production of N2O. Temperature has a significant influence on N2O emission, as a higher temperature results in a better N-removal efficiency and a lowered N2O production. Statistical analysis of the results showed that there is a strong correlation between nitrite accumulation and N2O production. Further, three regions of operation can be distinguished: a region with high N2O, NO and nitrite concentration; a region with high N2 concentrations and, as such, high removal percentages; and a region with high oxygen and nitrate concentrations. There is some overlap between the first two regions, which is in line with the fact that maximum emission of NO and N2O coincides with the region for optimal Anammox conversion. PMID:23393969

  5. Simulations of N2O concentrations for France using ecosystem models, emission databases and an atmospheric transport model

    NASA Astrophysics Data System (ADS)

    Massad, R. S.; Prieur, V.; Thompson, R.; Schultz, M.; Pison, I.; Bousquet, P.; Schmidt, M.; Lopez, M.; Boukari, E.; Lehuger, S.; Chaumartin, F.; Gabrielle, B.

    2012-04-01

    Soils are responsible for a major, although highly uncertain, share of the global emissions of nitrous oxide (N2O). N2O fluxes are strongly correlated to soil properties, soil management and local climatic conditions. These controlling factors interact at different temporal and spatial scales making it challenging to asses emissions at a regional level both with measurement and modeling. We used two biogeochemical simulation models CERES-EGC and O-CN to estimate N2O fluxes from agricultural soils over France, and compared them into the regional atmospheric chemistry-transport model CHIMERE (0.25°x0.25° for France). Comparisons between modelled and observed mixing ratios give insights on the quality of the emission scenarios used as input to the model, assuming small transport errors. The maps were tested by comparing CHIMERE simulations with time series of N2O atmospheric mixing ratios measured continuously in two locations over France during the year 2007. In an inverse mode, N2O emissions scenarios are used combination with N2O observed mixing ratios and an atmospheric transport model, to produce optimized emission scenarios. The model used is a global model (LMDZ-INCA, 3.75°x2.5° resolution with a 1°x1° zoom over Europe). For France the O-CN model which only accounts for crops and managed grassland emissions simulates total emissions of 95 Gg N-N2O/yr which are larger than total fluxes inferred from inversions (75 Gg N-N2O/yr). Inverted fluxes are 30% larger when compared to the prior emissions. Concerning CERES-EGC which only accounts for crops, the total emissions for 2007 sum-up to 20.4 Gg N-N2O/yr and are smaller than the total inverted flux.

  6. Estimating CH4 and N2O Emissions Using Tower Measurements in California

    NASA Astrophysics Data System (ADS)

    Jeong, S.; Zhao, C.; Hsu, Y.; Andrews, A. E.; Bianco, L.; Vaca, P.; Dlugokencky, E. J.; Wilczak, J. M.; Fischer, M. L.

    2011-12-01

    Based on an inverse modeling approach, we report spatio-temporally-resolved emissions for major non-CO2 greenhouse gases (CH4 and N2O) in California's Central Valley using measurements from a collaborative tower network. This large dataset, for the first time, allows quantification of the seasonal and inter-annual variations in California emissions, facilitating validation of uncertain state-wide annual emission totals that will be subject to future regulation by AB-32. Seasonally varying regional methane emissions (~100km) are estimated by scaling high-resolution (10-km scale) CH4 emission maps (initially tied to estimated state totals) for major known sources using a Bayesian inversion model to provide optimal agreement with aggregate mixing ratio data measured at the CARB-CEC-LBNL-NOAA 5-tower network. Two years of continuous CH4 measurements from the Walnut Grove (WGC) tall-tower indicate that annual CH4 emissions north of WGC (the southern end of the Sacramento Valley) are 2 - 3 times greater than the un-scaled inventory, with stronger summertime emissions that are likely driven by agriculture. South of WGC (in the Northern San Joaquin Valley) emissions are 0.9 - 1.5 times greater than the un-scaled inventory with small seasonal variation, where dairy emissions are expected to be dominant. Preliminary measurements from the 5-tower network suggest that long term data collected from those sites will greatly increase the ability to quantify and apportion CH4 emissions at 50 - 100 km scales over the entire Valley. Two years of daily N2O flask measurements from WGC indicate that N2O emissions are 2 - 3 times higher than the EDGAR3.2 emission inventory in Central California. Applying these scaling factors to the remainder of the California landscape suggests that total non-CO2 GHG's constitute 15 - 25% of California's total GHG emissions, and hence that mitigation of non-CO2 GHG emissions could meaningfully reduce California's overall GHG burden.

  7. Effects of Biochar Addition on CO2 and N2O Emissions following Fertilizer Application to a Cultivated Grassland Soil

    PubMed Central

    Chen, Jingjing; Kim, Hyunjin; Yoo, Gayoung

    2015-01-01

    Carbon (C) sequestration potential of biochar should be considered together with emission of greenhouse gases when applied to soils. In this study, we investigated CO2 and N2O emissions following the application of rice husk biochars to cultivated grassland soils and related gas emissions tos oil C and nitrogen (N) dynamics. Treatments included biochar addition (CHAR, NO CHAR) and amendment (COMPOST, UREA, NO FERT). The biochar application rate was 0.3% by weight. The temporal pattern of CO2 emissions differed according to biochar addition and amendments. CO2 emissions from the COMPOST soils were significantly higher than those from the UREA and NO FERT soils and less CO2 emission was observed when biochar and compost were applied together during the summer. Overall N2O emission was significantly influenced by the interaction between biochar and amendments. In UREA soil, biochar addition increased N2O emission by 49% compared to the control, while in the COMPOST and NO FERT soils, biochar did not have an effect on N2O emission. Two possible mechanisms were proposed to explain the higher N2O emissions upon biochar addition to UREA soil than other soils. Labile C in the biochar may have stimulated microbial N mineralization in the C-limited soil used in our study, resulting in an increase in N2O emission. Biochar may also have provided the soil with the ability to retain mineral N, leading to increased N2O emission. The overall results imply that biochar addition can increase C sequestration when applied together with compost, and might stimulate N2O emission when applied to soil amended with urea. PMID:26020941

  8. Source portioning of N_{2}O emissions after long term elevation of soil temperature in a permanent grassland soil

    NASA Astrophysics Data System (ADS)

    Jansen-Willems, Anne; Lanigan, Gary; Clough, Timothy; Andresen, Louise; Müller, Christoph

    2016-04-01

    Several methods, such as source portioning, have been used to quantify the contributions of individual N pools to N2O emissions. These methods however, assume the absence of hybrid reactions such as co-denitrification, which were previously identified as important. A straight forward method portioning N2O fluxes into four different production processes, including a hybrid reaction, was therefore developed. This method portioned the N2O fluxes in nitrification, denitrification, oxidation of organic matter and co-denitrification, using data on 45R and 46R of the N2O flux and the 15N content of the NO3‑ and NH4+ in the soil. This newly developed method was used to analyse the N2O emissions from incubated soil, which was previously subjected to 6 years of elevated soil temperature of +0, +1, +2 or +3 ° C. N2O emissions were measured and analysed at four time points in the six days following, NO315NH4 Gly or 15NO3NH4 Gly, label addition. The oxidation of organic N was found to be the main source of N2O fluxes at all sampling dates, comprising between 63 and 85% of the total N2O flux. The percentage contribution made by organic N to N2O fluxes increased over the sampling period, rising from a minimum of 40% in the control treatment, to virtually 100% across all treatments by Day 6. Compared to the control treatment, denitrification contributed less to N2O from soil subjected to +2 and +3 ° C warming (p <0.0001 and p=0.002, respectively). Co-denitrification only contributed to the N2O flux during the first day after substrate addition. The highest amount of N2O produced via co-denitrification was found under the control treatment. From soil subjected to +2 and +3 ° C treatments, the contribution of co-denitrification was minor. However, these differences in co-denitrification were not significant. This research showed the importance of the oxidation of organic N in N2O emissions. It should therefore not be omitted as a potential source in source portioning. Emissions

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

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

    PubMed

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

    2015-03-15

    A continuous, on-line quantification of the nitrous oxide (N2O) emissions from a full-scale sequencing batch reactor (SBR) placed in a municipal wastewater treatment plant (WWTP) was performed in this study. In general, N2O emissions from the biological wastewater treatment system were 97.1 ± 6.9 g N2O-N/Kg [Formula: see text] consumed or 6.8% of the influent [Formula: see text] load. In the WWTP of this study, N2O emissions accounted for over 60% of the total carbon footprint of the facility, on average. Different cycle configurations were implemented in the SBR aiming at reaching acceptable effluent values. Each cycle configuration consisted of sequences of aerated and non-aerated phases of different time length being controlled by the ammonium set-point fixed. Cycles with long aerated phases showed the largest N2O emissions, with the consequent increase in carbon footprint. Cycle configurations with intermittent aeration (aerated phases up to 20-30 min followed by short anoxic phases) were proven to effectively reduce N2O emissions, without compromising nitrification performance or increasing electricity consumption. This is the first study in which a successful operational strategy for N2O mitigation is identified at full-scale. PMID:25577689

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

    PubMed

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

    2016-03-01

    Perennial crops can deliver a wide range of ecosystem services compared to annual crops. Some of these benefits are achieved by lengthening the growing season, which increases the period of crop water and nutrient uptake, pointing to a potential role for perennial systems to mitigate soil nitrous oxide (N2 O) emissions. Employing a micrometeorological method, we tested this hypothesis in a 3-year field experiment with a perennial grass-legume mixture and an annual corn monoculture. Given that N2 O emissions are strongly dependent on the method of fertilizer application, two manure application options commonly used by farmers for each crop were studied: injection vs. broadcast application for the perennial; fall vs. spring application for the annual. Across the 3 years, lower N2 O emissions (P < 0.001) were measured for the perennial compared to the annual crop, even though annual N2 O emissions increased tenfold for the perennial after ploughing. The percentage of N2 O lost per unit of fertilizer applied was 3.7, 3.1 and 1.3 times higher for the annual for each consecutive year. Differences in soil organic matter due to the contrasting root systems of these crops are probably a major factor behind the N2 O reduction. We found that a specific manure management practice can lead to increases or reductions in annual N2 O emissions depending on environmental variables. The number of freeze-thaw cycles during winter and the amount of rainfall after fertilization in spring were key factors. Therefore, general manure management recommendations should be avoided because interannual weather variability has the potential to determine if a specific practice is beneficial or detrimental. The lower N2 O emissions of perennial crops deserve further research attention and must be considered in future land-use decisions. Increasing the proportion of perennial crops in agricultural landscapes may provide an overlooked opportunity to regulate N2 O emissions. PMID:26491961

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Partitioning Residue-derived and Residue-induced Emissions of N2O Using 15N-labelled Crop Residues

    NASA Astrophysics Data System (ADS)

    Farrell, R. E.; Carverhill, J.; Lemke, R.; Knight, J. D.

    2014-12-01

    Estimates of N2O emissions in Canada indicate that 17% of all agriculture-based emissions are associated with the decomposition of crop residues. However, research specific to the western Canadian prairies (including Saskatchewan) has shown that the N2O emission factor for N sources in this region typically ranges between 0.2 and 0.6%, which is well below the current IPCC default emission factor of 1.0%. Thus, it stands to reason that emissions from crop residues should also be lower than those calculated using the current IPCC emission factor. Current data indicates that residue decomposition, N mineralization and N2O production are affected by a number of factors such as C:N ratio and chemical composition of the residue, soil type, and soil water content; thus, a bench-scale incubation study was conducted to examine the effects of soil type and water content on N2O emissions associated with the decomposition of different crop residues. The study was carried out using soils from the Black, Dark Brown, Brown, and Gray soil zones and was conducted at both 50% and 70% water-filled pore space (WFPS); the soils were amended with 15N-labeled residues of wheat, pea, canola, and flax, or with an equivalent amount of 15N-labeled urea; 15N2O production was monitored using a Picarro G5101-i isotopic N2O analyzer. Crop residue additions to the soils resulted in both direct and indirect emissions of N2O, with residue derived emissions (RDE; measured as 15N2O) generally exceeding residue-induced emissions (RIE) at 50% WFPS—with RDEs ranging from 42% to 88% (mean = 58%) of the total N2O. Conversely, at 70% WFPS, RDEs were generally lower than RIEs—ranging from 21% to 83% (mean = 48%). Whereas both water content and soil type had an impact on N2O production, there was a clear and consistent trend in the emission factors for the residues; i.e., emissions were always greatest for the canola residue and lowest for the wheat residue and urea fertilizer; and intermediate for pea

  14. Evaluating Observational Constraints on N2O Emissions via Information Content Analysis Using GEOS-Chem and its Adjoint

    NASA Astrophysics Data System (ADS)

    Wells, K. C.; Millet, D. B.; Bousserez, N.; Henze, D. K.; Chaliyakunnel, S.; Griffis, T. J.; Dlugokencky, E. J.; Prinn, R. G.; O'Doherty, S.; Weiss, R. F.; Dutton, G. S.; Elkins, J. W.; Krummel, P. B.; Langenfelds, R. L.; Steele, P.

    2015-12-01

    Nitrous oxide (N2O) is a long-lived greenhouse gas with a global warming potential approximately 300 times that of CO2, and plays a key role in stratospheric ozone depletion. Human perturbation of the nitrogen cycle has led to a rise in atmospheric N2O, but large uncertainties exist in the spatial and temporal distribution of its emissions. Here we employ a 4D-Var inversion framework for N2O based on the GEOS-Chem chemical transport model and its adjoint to derive new constraints on the space-time distribution of global land and ocean N2O fluxes. Based on an ensemble of global surface measurements, we find that emissions are overestimated over Northern Hemisphere land areas and underestimated in the Southern Hemisphere. Assigning these biases to particular land or ocean regions is more difficult given the long lifetime of N2O. To quantitatively evaluate where the current N2O observing network provides local and regional emission constraints, we apply a new, efficient information content analysis technique involving radial basis functions. The technique yields optimal state vector dimensions for N2O source inversions, with model grid cells grouped in space and time according to the resolution that can actually be provided by the network of global observations. We then use these optimal state vectors in an analytical inversion to refine current top-down emission estimates.

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

    Liu, Yuhong; Wang, Lixin; Bao, Shumei; Liu, Huamin; Yu, Junbao; Wang, Yu; Shao, Hongbo; Ouyang, Yan; An, Shuqing

    2014-01-01

    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. PMID:24892044

  18. [N2O emission and control in shortcut nitrification and denitrification and simultaneous nitrification and denitrification biological nitrogen removal systems].

    PubMed

    Zhang, Jing-rong; Wang, Shu-ying; Shang, Hui-lai; Peng, Yong-zhen

    2009-12-01

    SBR reactors were used to investigate the N2O emission in shortcut nitrification and simultaneous nitrification and denitrification (SND). Shortcut nitrification with nitrosation rate above 90% was realized by real-time control strategy. The N2O emission and variation of nitrosation rate were investigated under 4 DO levels (0.5, 1.0, 1.5, 2.0 mg/L). The results turned out that the optimal DO to maintain high nitrosation rate and minimum N2O emission was 1.5 mg/L and the N4O emission was 0.06 g per ammonium removed. The SBR filled with carbon fiber performed under low DO and pulse feeding. The SND rate was over 79% during the experiment. The N2O emission was studied under DO 0.2, 0.4, 1.0 and 1.5 mg/L. It turned out that the optimal DO was 1.0 mg/L and the N2O emission was 0.021 g per ammonium removed. Compared to the shortcut nitrification, the N2O emission of SND was 1/3 of the short-cut nitrification under optimal DO. PMID:20187398

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

    PubMed

    Eldyasti, Ahmed; Nakhla, George; Zhu, Jesse

    2014-12-20

    Nitrous oxide (N2O) is a significant anthropogenic greenhouse gas emitted from biological nutrient removal (BNR) processes. This study tries to get a deeper insight into N2O emissions from denitrifying fluidized bed bioreactors (DFBBRs) and its relationship to the biofilm thickness, diffusivity, and reaction rates. The DFBBR was operated at two different organic and nitrogen loading rates of 5.9–7 kg COD/(m3 d) and 1.2–2 kg N/(m3 d), respectively. Results showed that the N2O conversion rate from the DFBBR at a biofilm thickness of 680 μm was 0.53% of the total influent nitrogen loading while at the limited COD and a biofilm thickness of 230 μm, the N2O conversion rate increased by 196–1.57% of the influent nitrogen loading concomitant with a sevenfold increase in liquid nitrite concentration. Comparing the N2O emissions at different biofilm thickness showed that the N2O emission decreased exponentially with biofilm thickness due to the retention of slow growth denitrifiers and the limited diffusivity of N2O. PMID:25450644

  20. Denitrifier communities in tank bromeliads and prospected N2O emissions from tank substrate upon increasing N-deposition

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    It is well known that tropical rainforest soils with total emissions of 1.34 Tg N/yr from the tropics, play a significant role in the global N2O emissions scenarios. Significant contributions were reported particularly for tropical rainforest soils in South and Central America due to the large areas covered by rainforest in this region. In tropical rainforests of the Americas tank bromeliads constitute a prominent group of plants and were shown to significantly contribute to the production of the greenhouse gas methane from tropical forests. It is, however, essentially unknown whether and how bromeliads may contribute to the production of N2O, another important greenhouse gas. It is also unknown whether N2O emissions relate to atmospheric N-deposition and whether an increase in emissions is to be expected upon the prospected increase in N-deposition. We studied the propensity of tank substrate of the bromeliad Werauhia gladioliflora to emit N2O and how this potential is related to the underlying denitrifier communities. In tropical forests of Costa Rica Werauhia gladioliflora is very abundant with 9.85 specimen m-2. Incubation of the tank substrate with increasing amounts of fertilizer to reflect predicted N-deposition scenarios resulted in proportionally increasing net N2O production. Based on the abundance of Werauhia gladioliflora we estimated annual emissions of 395 µg N2O-N m-2 day-1 for N-deposition levels to date which is in the range of tropical soils. At a surplus of N 70% of N2O produced were not reduced leading to accumulation of N2O which agreed well with the finding that 95% of the denitrifiers detected lacked a gene encoding a N2O-reductase and are therefore unable to reduce N2O to dinitrogen. Generally, denitrifiers were highly abundant and ready to denitrify immediately after provision of a nitrogen source because carbon is non-limiting in tank substrate. Our results suggest that tank bromeliad substrate may be a significant source of N2O in

  1. Emissions of N2O, CH4 and CO2 from tropical forest soils

    NASA Technical Reports Server (NTRS)

    Keller, Michael; Kaplan, Warren A.; Wofsy, Steven C.

    1986-01-01

    Emissions of nitrous oxide, methane, and carbon dioxide were measured at diverse locations in tropical forests of Brazil, Ecuador, and Puerto Rico using a static open chamber technique. Mean fluxes to the atmosphere were 1.7 x 10 to the 10th, -0.7 x 10 to the 10th, and 1.5 x 10 to the 14th molecules/sq cm per s for N2O, CH4, and CO2, respectively. The data indicate that tropical forests contribute a significant fraction of the global source for atmospheric N2O, about 40 percent of the current source, and possibly 75 percent of the preindustrial source. Methane is consumed by soils on average, but the sink is an insignificant part (less than 5 percent) of the atmospheric cycle for the gas. Emissions of CO2 from forest soils are higher at equatorial sites than at middle or high latitudes, as expected from ecological considerations. Soils emit CO2 at rates more than twice as large as the rate of carbon infall in litter; hence much of the emitted CO2 must arise from root metabolism.

  2. Contrasting effects of exogenous phosphorus application on N2O emissions from two tropical forest soils with contrasting phosphorus availability.

    PubMed

    Mori, Taiki; Yokoyama, Daiki; Kitayama, Kanehiro

    2016-01-01

    An incubation study was conducted to test the effects of phosphorus (P) addition on nitrous oxide (N2O) emissions from the soils taken from two tropical rain forests established on different parent materials [meta-sedimentary (MS) and ultrabasic (UB) rock] on Mt. Kinabalu, Borneo. Earlier studies suggest that the forest on UB soils is more strongly limited by P than that on MS soils is. In MS soils, P addition significantly reduced N2O emissions. Since neither ammonium (NH4 (+)) nor nitrate (NO3 (-)) contents were reduced by P addition, we assumed that the decrease in N2O emissions were not due to the previously-reported mechanism: P addition stimulated microbial nitrogen (N) immobilization and collateral inorganic N consumption, reducing resources for producing N2O. Since P addition enhanced the ratios of microbial biomass to CO2 and N2O emissions (indicators of nitrifying and/or denitrifying respiratory efficiency), it was suggested that the N required for the respiration of nitrifying and/or denitrifying bacteria was reduced, leading to reduced N2O emissions. On the other hand, P addition had no effects on N2O emissions in UB soils. The respiratory efficiency did not change significantly by P addition, possibly because the microbial community in the highly-P-depleted UB soils shifted by P addition, with which the enhancement of respiration efficiency did not co-vary. We concluded that (1) P addition may control N2O emissions through increasing respiratory efficiency, and (2) the effects may be different depending on the differences in P availability. PMID:27536520

  3. N2O and NO2 Emissions from Heavy-Duty Diesel Trucks with Advanced Emission Controls

    NASA Astrophysics Data System (ADS)

    Preble, C.; Harley, R.; Kirchstetter, T.

    2014-12-01

    Diesel engines are the largest source of nitrogen oxides (NOx) emissions nationally, and also a major contributor to the black carbon (BC) fraction of fine particulate matter (PM). Recently, diesel particle filter (DPF) and selective catalytic reduction (SCR) emission control systems that target exhaust PM and NOx have become standard equipment on new heavy-duty diesel trucks. However, the deliberate catalytic oxidation of engine-out nitric oxide (NO) to nitrogen dioxide (NO2) in continuously regenerating DPFs leads to increased tailpipe emission of NO2. This is of potential concern due to the toxicity of NO2 and the resulting increases in atmospheric formation of other air pollutants such as ozone, nitric acid, and fine PM. While use of SCR reduces emissions of both NO and NO2, it may lead to increased emissions of nitrous oxide (N2O), a potent greenhouse gas. Here we report results from on-road measurements of heavy-duty diesel truck emissions conducted at the Port of Oakland and the Caldecott Tunnel in the San Francisco Bay Area. Emission factors (g pollutant per kg of diesel) were linked via recorded license plates to individual truck attributes, including engine model year and installed emission control equipment. Between 2009 and 2013, the fraction of DPF-equipped trucks at the Port of Oakland increased from 2 to 99%, and median engine age decreased from 11 to 6 years. Over the same period, fleet-average emission factors for black carbon and NOx decreased by 76 ± 22% and 53 ± 8%, respectively. However, direct emissions of NO2 increased, and consequently the NO2/NOx emission ratio increased from 0.03 ± 0.02 to 0.18 ± 0.03. Older trucks retrofitted with DPFs emitted approximately 3.5 times more NO2 than newer trucks equipped with both DPF and SCR. Preliminary data from summer 2014 measurements at the Caldecott Tunnel suggest that some older trucks have negative emission factors for N2O, and that for newer trucks, N2O emission factors have changed sign and

  4. N2O emission from full-scale urban wastewater treatment plants: a comparison between A(2)O and SBR.

    PubMed

    Sun, Shichang; Cheng, Xiang; Li, Sha; Qi, Fei; Liu, Yan; Sun, Dezhi

    2013-01-01

    The emission of nitrous oxide (N2O) from full-scale anoxic/anaerobic/oxic (A(2)O) and sequencing batch reactor (SBR) processes was measured to evaluate N2O emission from urban wastewater treatment plants (WWTPs). The results showed that N2O flux in the A(2)O WWTP followed an order of A(2)O-oxic zone > aerated grit tank > A(2)O-anaerobic zone > A(2)O-anoxic zone > final clarifier > primary clarifier, while in the SBR WWTP the order was SBR tank > swirl grit tank > wastewater distribution tank and within the SBR tank in an order of SBR-feeding period > SBR-aeration period > SBR-settling period > SBR-decanting period. N2O emission from the A(2)O WWTP was approximately 486.61 kg d(-1), 96.9% of which was from the A(2)O-oxic zone. In the SBR WWTP, the emission of N2O was 339.24 kg d(-1) with 99.9% of the total emission coming from the periods of feeding and aeration. There was 6.52% of nitrogen-load in the influent being transformed to the emitted N2O in the SBR WWTP; the percentage was 3.35 times higher than that in the A(2)O WWTP. PMID:23656929

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

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed

    Kim, Dong-Jin; Kim, Yuri

    2013-01-01

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

  7. Effects of soil moisture and temperature on NO, NO2, and N2O emissions from European forest soils

    NASA Astrophysics Data System (ADS)

    Schindlbacher, Andreas; Zechmeister-Boltenstern, Sophie; Butterbach-Bahl, Klaus

    2004-09-01

    Emissions of NO, NO2, and N2O to the atmosphere were measured with a fully automated laboratory system from undisturbed soil columns obtained from five different temperate and one boreal forest sites. The soils were chosen to cover a transect through Europe, sandy and loamy textures, and different atmospheric nitrogen deposition rates. In a two-factorial experimental design, soil cores were kept under varying conditions with respect to temperature (range 5-20°C) and soil moisture (range 0-300 kPa). The combination of soil temperature and soil moisture could explain a better part of variations in NO (up to 74%) and N2O (up to 86%) emissions for individual soils, but average emissions differed significantly between various forest soils. Generally, NO and N2O were emitted from all soils except from the boreal pine forest soil, where NO was consumed. NO emissions from the German spruce forest receiving highest yearly nitrogen inputs of >35 kg ha-1 yr-1 ranged from 1.3 to 608.9 μg NO-N m-2 h-1 and largely exceeded emissions from other soils. Average N2O emissions from this soil tended also to be highest (171.7 ± 42.2 μg N2O-N m-2 h-1), but did not differ significantly from other soils. NO2 deposition occurred in all soils and strongly correlated to NO emissions. NO and N2O emissions showed a positive exponential relationship to soil temperature. With activation energies between 57 and 133 kJ mol-1, N2O emissions from the various soils responded more uniformely to temperature than NO emissions with 41 and 199 kJ mol-1. The two Austrian beech forest soils showed exceptionally high activation energies for NO emissions, which might be attributed to chemodenitrification. N2O emissions increased with increasing water filled pore space (WFPS) or decreasing water tension, respectively. Maximal N2O emissions were measured between 80 and 95% WFPS or 0 kPa water tension. Optimal moisture for NO emission differed significantly between the soils, and ranged between 15% WFPS in

  8. Effect of fertilizer and water content on N2O emission from three plantation soils in south China.

    PubMed

    Li, Zhi-an; Zou, Bi; Xia, Han-ping; Ding, Yong-zhen; Tan, Wan-neng; Ma, Zhen-rong

    2005-01-01

    The effects of fertilizers and water content on N2O emission were studied using the three most typical plantation soils. Soil incubations were performed and fertilization and water content treatments were designed. At 25% of saturated water content(SWC), N2O emissions from the soil treated with urea, KNO3, (NH4)2 SO4 and KH2 PO4 were compared at application rates of 0, 100, 200, 300 and 500 kg/hm2. At 80% of SWC, similar experiments were carried out but at only one application rate(500 kg/hm2). N2O emissions at various water contents(20%, 35%, 50%, 65%, 80% and 100% of SWC) were studied. At low water content(25% of SWC), neither nitrogen nor phosphorus(or potassium) fertilizers led to a high level of N2O emission, which generally ranged from 2.03 to 29.02 microg/(m2 x h). However, at high water content(80% SWC), the fertilizers resulted in much greater N2O emission irregardless of soil tested. The highest N2O emission rates after 24 h of water addition were 1233 microg/(m2 x h) for S. superba soil, 1507 microg/(m2 x h) for P. elliottii soil and 1869 microg/ (m2 x h) for A. mangium soil respectively. N2O emission from soils treated with urea, (NH4)2 SO4 and KH2 PO4 immediately dropped to a low level but steadily increased to a very high level for the soil treated with KNO3. High NO3- content was a basis of high level of N2O emission. N2O emission rates from soils peaked shortly after flooding, rapidly dropping to a very low level in soil from non-legume plantations, but lasting for a relatively long period in soil from legume plantations. When soil water content increased equaling to or higher than 65%, the accumulated N2O emission over a period of 13 d ranged from 20.21-29.78 mg/m2 for S. superba, 30.57-70.12 mg/m2 for P. elliottii and 300.89-430.51 mg/m2 for A. mangium. The critical water content was 50% of SWC, above which a high level of N2O emission could be expected, and below which very little N2O emissions were detected. The results suggest that, at low

  9. [Effects of conservation tillage on soil CO2 and N2O emission during the following winter-wheat season].

    PubMed

    Pan, Ying; Hu, Zheng-Hu; Wu, Yang-Zhou; Sun, Yin-Yin; Sheng, Lu; Chen, Shu-Tao; Xiao, Qi-Tao

    2014-07-01

    In order to study the effect of conservation tillage on soil CO2 and N2O emissions in the following crop-growing season, field experiments were conducted in the winter wheat-growing season. Four treatments were conventional tillage (T), no-tillage with no straw cover (NT), no-tillage with straw cover (NTS), and conventional tillage with straw incorporation (TS), respectively. The CO2 and N2O fluxes were measured using a static chamber-gas chromatograph technique. The results showed that in the following winter wheat-growing season, conservation tillage did not change the seasonal pattern of CO2 and N2O emission fluxes from soil, and had no significant effect on crop biomass. Conservation tillage significantly reduced the accumulative amount of CO2 and N2O. Compared with the T treatment, the accumulative amount of CO2 under TS, NT, and NTS treatments were reduced by 5.95% (P = 0.132), 12.94% (P = 0.007), and 13.91% (P = 0.004), respectively, and the accumulative amount of N2O were significantly reduced by 31.23% (P = 0.000), 61.29% (P = 0.000), and 33.08% (P = 0.000), respectively. Our findings suggest that conservation tillage significantly reduced CO2 and N2O emission from soil in the following winter wheat-growing season. PMID:25244867

  10. Biochar and denitrification in soils: when, how much and why does biochar reduce N2O emissions?

    PubMed Central

    Cayuela, Maria Luz; Sánchez-Monedero, Miguel Angel; Roig, Asunción; Hanley, Kelly; Enders, Akio; Lehmann, Johannes

    2013-01-01

    Agricultural soils represent the main source of anthropogenic N2O emissions. Recently, interactions of black carbon with the nitrogen cycle have been recognized and the use of biochar is being investigated as a means to reduce N2O emissions. However, the mechanisms of reduction remain unclear. Here we demonstrate the significant impact of biochar on denitrification, with a consistent decrease in N2O emissions by 10–90% in 14 different agricultural soils. Using the 15N gas-flux method we observed a consistent reduction of the N2O/(N2 + N2O) ratio, which demonstrates that biochar facilitates the last step of denitrification. Biochar acid buffer capacity was identified as an important aspect for mitigation that was not primarily caused by a pH shift in soil. We propose the function of biochar as an “electron shuttle” that facilitates the transfer of electrons to soil denitrifying microorganisms, which together with its liming effect would promote the reduction of N2O to N2. PMID:23615819

  11. Affect of dairy cow manure, urine, and slurry on N<2>O, CO<2>, and CH<4> emissions from Pasture

    NASA Astrophysics Data System (ADS)

    Dorich, C.; Varner, R. K.; Contosta, A.; Li, C.

    2012-12-01

    Agriculture is responsible for roughly 25% of total anthropogenic emission of greenhouse gases (GHG) globally. These agricultural emissions are primarily in the form of methane (CH<4>) and nitrous oxide (N<2>O) where they account for roughly 40 and 80 percent of anthropogenic emissions of their gas, respectively. Measuring and modeling of these gases has remained difficult however as management varies between farms and N<2>O fluxes have been difficult to link to climate and site conditions. Most of these N<2>O fluxes occur during soil freeze-thaw and wetting-drying cycles as well as fertilizer addition moments, all of which are difficult to measure and harder yet to model. Thus the N<2>O flux remains poorly understood and may be underestimated in literature. This provides a problem in agriculture emissions as N use efficiency has been suggested as a proxy for farm scale emissions. On a farm scale these large fluxes of N<2>O from soil "hot moments" can account for up to 60% of the total GHG emissions and thus it is essential to capture the full flux. At the University of New Hampshire Agriculture Experiment Station's (NHAES) organic dairy farm a manure fertilizer experiment was conducted. Manure, urine, and slurry from the UNH dairy farms were collected, analyzed, and applied to pasture plots in May 2012 in order to examine N<2>O flux hot moments. Sites were measured at least bi-weekly with manual static flux chambers taken with soil temperature and moisture along with measurements for soil inorganic N, soil C:N, plant biomass and C:N, and soil pH. Gas samples were analyzed for CO<2>, CH<4>, and N<2>O. Emissions were compared with other fluxes from the farm ecosystem including; corn silage, free stall bedding, composting and solid manure, and a manure slurry tank.

  12. Wetting-induced pulses produced unexpectedly high emissions of N2O and NOx in a desert ecosystem

    NASA Astrophysics Data System (ADS)

    Eberwein, J. R.; Carey, C.; Aronson, E. L.; Jenerette, D.

    2015-12-01

    Approximately one third of Earth's land surface is subjected to arid conditions, and aridland soils have the potential for significant feedbacks to global climate change drivers, such as anthropogenic nitrogen deposition. This study examined wetting-induced pulses of N2O and NOx along a nitrogen deposition gradient in the Colorado Desert of southern California. Measurements were made before and following water (to simulate a 2 cm rain event) and nitrogen plus water additions (30 kg NH4NO3 ha-1) at 15 minutes, 12 hours and 24 hours post-wetting. We found nitrogenous fluxes that were substantially higher than expected. N2O fluxes, in particular were remarkably high reaching up to 200 ng N2O-N m-2 s-1, similar to agriculture levels and in the range of peat bog emissions. There was a clear transition between N2O emissions, which peaked 15 minutes after wetting, and NOx emissions, which peaked at the 12 hour timepoint. NOx emissions were also considerable, reaching as high as 350 ng NOx-N m-2 s-1. Both N2O and NOx fluxes responded strongly to water additions, demonstrating a clear wetting-induced pulse response. While N2O was not affected by nitrogen additions, NOx fluxes demonstrated a significant increase with nitrogen plus water over water alone (p=0.016). These results suggest that gaseous nitrogen export, particularly N2O emissions, is a greater form of nitrogen loss in arid systems than is currently assumed. This potential for high nitrogen emissions and the capacity for anthropogenic nitrogen deposition to increase these emissions present serious implications for local air quality and significant soil feedbacks to climate change.

  13. On-road measurement of NH3 and N2O emissions from a Euro V heavy-duty vehicle

    NASA Astrophysics Data System (ADS)

    Suarez-Bertoa, Ricardo; Mendoza-Villafuerte, Pablo; Bonnel, Pierre; Lilova, Velizara; Hill, Leslie; Perujo, Adolfo; Astorga, Covadonga

    2016-08-01

    The use of selective catalytic reduction systems (SCR) to abate NOx vehicular emissions brings new concerns on the emissions of the byproducts NH3 and N2O. Therefore, NH3 and N2O on-road emissions from a Euro V truck equipped with a SCR were measured in real time using a QCL-IR. Results bring to light possibility to perform this kind of real time measurements for other pollutants besides, hydrocarbons, NOx, CO and CO2. The capability to measure NH3 and N2O in a second-by-second basis will allow applying the currently agreed regulatory emissions evaluation for gaseous compounds. Average N2O emission factors calculated applying the current PEMS-based data analysis to all available windows from the tests ranged from 0.063 g/kWh to 0.139 g/kWh. Average NH3 concentrations ranged from 0.9 ppm to 5.7 ppm. Although calculated average N2O and NH3 emissions were within current limits, NOx emissions were substantially higher than Euro V limits under the studied conditions.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

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

    2010-08-01

    This study quantified spatiotemporal patterns of CH4 and N2O emissions from livestock and poultry production in Turkey between 1961 and 2007. CH4(enteric) (from enteric fermentation), CH4(manure) (from manure management), and N2O(AWM) (from animal waste management) emissions in Turkey were estimated at 1,164, 216, and 55 Gg in 1961 and decreased to 844, 187, and 39 Gg in 2007, contributing a share of roughly 2% to the global livestock-related CH4 emissions and %1.5 to the global N2O(AWM) emissions, respectively. Total CO2-eq emissions were estimated at 50.7 Tg in 1961 and declined from a maximum value of 60.7 Tg in 1982 to a minimum value of 34.5 Tg in 2003, with a mean emission rate of 48 Tg year(-1) due to a significant reduction in the number of ruminant livestock. The highest mean share of emissions belonged to West Black Sea (14% and 16%) for CH4(enteric) and CH4(manure) and to North East Anatolia (12% and %13) for N2O(AWM) and total CO2-eq emissions, respectively. The highest emission density was 1.7 Mg km(-2) year(-1) for CH4(enteric), 0.3 Mg km(-2) year(-1) for CH4(manure), and 0.07 Mg km(-2) year(-1) for the total CO2-eq emissions in the West and North East Anatolia regions and 0.09 Mg km(-2) year(-1) for N2O(AWM) in the East Marmara region. Temporal and spatial variations in CH4(enteric), CH4(manure), and N2O(AWM) emissions in Turkey were estimated using regression models and ordinary kriging at a 500-m resolution, respectively. PMID:19609697

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed Central

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

    1999-01-01

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

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

    PubMed

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

    1999-08-01

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

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

    PubMed

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

    2016-07-19

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

  1. Tracing changes of N2O emission pathways in a permanent grassland under elevated atmospheric CO2 concentrations

    NASA Astrophysics Data System (ADS)

    Gorenflo, Andre; Moser, Gerald; Brenzinger, Kristof; Elias, Dafydd; McNamara, Neill; Clough, Tim; Maček, Irena; Vodnik, Dominik; Braker, Gesche; Schimmelpfennig, Sonja; Gerstner, Judith; Müller, Christoph

    2015-04-01

    The increase of greenhouse gases (GHG) in the atmosphere is of concern due to its effect on global temperatures. Nitrous oxide (N2O) with a Global Warming Potential of 298 over a 100 year period is of particular concern because strong feedback effects of elevated atmospheric CO2 on N2O emissions have been observed. However, so far the changes in processes which are responsible for such a feedback effect are only poorly understood. Our study was carried out in situ in a long-term Free Air Carbon dioxide Enrichment (FACE) study on permanent grassland at atmospheric CO2 concentrations 20% above ambient which expected at the middle of this century. We performed an in situ 15N tracing with differentially labelled NH4NO3 to trace the main N2O emission pathways. Over a period of more than one year we monitored at least weakly the N2O emissions with the closed chamber technique and analyzed the 15N signature of the N2O. The observed gaseous emissions under ambient and elevated atmospheric CO2 were associated with the observed gross N transformations and the microbial activities to identify the main emission pathways under ambient and elevated CO2.

  2. Atmospheric emissions of N2O deduced from long-term observations at the Mediterranean Island of Lampedusa

    NASA Astrophysics Data System (ADS)

    Artuso, Florinda; Piacentino, Salvatore; Sferlazzo, Damiano; Disarra, Alcide; Meloni, Daniela; Monteleone, Francesco; Chamard, Paolo; Frezzotti, Massimo

    2010-05-01

    Nitrous oxide (N2O) is the third principal long-lived greenhouse gas (GHG) emitted by human activities, as it has been assessed by the last Intergovernmental Panel on Climate Change (IPCC) report. It is produced both naturally and anthropogenically. Natural sources include microbial processes of nitrification and denitrification in soils and water. Use of nitrate and ammonium fertilizers increased noteworthy the emission of N2O from soils. Other anthropogenic sources of N2O are fuel combustion and waste management activities. Its mixing ratio in the atmosphere has considerably risen during the past two centuries as demonstrated by analyses of polar ice cores. Long-term observations of GHG atmospheric concentration are crucial in the investigation of global climate changes and are essential for the prediction of their future trends. For this reason a number of global monitoring studies aimed at determining trends and distribution in the tropospheric abundance of N2O and other GHGs have been carried out during the last years. Scarce information on the magnitude and distribution of N2O emissions is available in the Mediterranean area. In this work we present and analyse long-term N2O records measured at the remote site of Lampedusa Island, located in the middle of the Mediterranean basin. Lampedusa is part of the majors GHG global monitoring programs such as the Global Atmosphere Watch (GAW), established by the World Meteorological Organization, and the National Oceanic and Atmospheric Administration (NOAA) networks. Monitoring of the atmospheric mixing ratio of N2O has been started in Lampedusa in 1996 on a weekly basis but also continuous measurements have been carried out since October 2005. Weekly records are analyzed and the linear trend line has been used to evaluate the annual growth rate. In agreement with data reported by the IPCC 4th Assessment Report, the mean N2O value recorded at Lampedusa in this period is 319.6±0.6 ppb. This finding remarks the

  3. Bioenergy residues applied as soil amendments: N2O emissions and C sequestration potential

    NASA Astrophysics Data System (ADS)

    Cayuela, M.; Kuikman, P.; Oenema, O.; Bakker, R.; van Groenigen, J.

    2009-12-01

    most stable residues with the lowest CO2 loss between 0.5 and 5.8 % of total added C. Regarding N2O emissions, first generation biofuel residues led to the highest total N2O emissions (between 2.5 - 6.0% of added N). Second generation biofuel residues emitted between 1.0-2.0% of added N, whereas anaerobic digestates led to emissions lower than 1% of added N. The two biochars used in this study led to negative N2O emissions, i.e. lower than the blank soil. We conclude that, at least in the short term, the effects of biofuel residues on the combined greenhouse gas balance of the soil ranges from beneficial (biochar) via mixed (digestates, second generation biofuels) to manifestly detrimental (first generation biofuels). These effects should be taken into account in life cycle analyses of biofuel production.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  5. Mechanism study on the influence of in situ SOx removal on N2O emission in CFB boiler

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    The influence of in situ deSOx process on N2O emission in CFB boiler was studied using density functional theory calculations. The competitive adsorption of SO2 and N2O on pure CaO (1 0 0) surface was first studied and the reaction priority was determined. Results showed that SO2 was more likely to adsorb on CaO (1 0 0) surface O anion site, which hindered the catalytic decomposition of N2O on CaO (1 0 0) surface and sulfurized the CaO (1 0 0) surface under reducing atmosphere. Then a partially sulfurized CaO (1 0 0) surface was established to study the catalytic activity of deSOx reaction intermediate on N2O decomposition. The O atom transfer process and the surface recovery process were two key steps for N2O decomposition and the rate-determining step was the latter one. The sulfurization of the surface could deactivate its catalytic activity on N2O decomposition compared with pure CaO (1 0 0) surface but it was still better than that of pure CaS (1 0 0) surface. The free Gibbs energy was calculated to incorporate the temperature dependence of respective reactions. When temperature was higher than 373 K, the surface recovery was more likely to proceed via the LH route.

  6. Footprint methods to separate N2O emission rates from adjacent paddock areas.

    PubMed

    Mukherjee, Sandipan; McMillan, Andrew M S; Sturman, Andrew P; Harvey, Mike J; Laubach, Johannes

    2015-03-01

    Using micrometeorological techniques to measure greenhouse gas emissions from differently treated adjacent plots is a promising avenue to verify the effect of mitigation strategies at the field scale. In pursuing such an approach, it is crucial to accurately characterize the source area of the fluxes measured at each sampling point. Hence, a comprehensive footprint analysis method is required so that emission rates can be obtained for a specific field within a biochemically heterogeneous area. In this study, a footprint analysis method is developed to estimate the emission for an experiment where the flux of N2O is measured from several control and treated plots. The emission rate of an individual plot is estimated using an inverse footprint fraction approach where the footprint fractions are obtained from an analytical footprint model. A numerical solution for obtaining the background flux for such a multiplot measurement system is also provided. Results of the footprint analysis method are assessed, first, by comparing footprint fractions obtained from both an analytical footprint model and a "forward" simulation of a backward Lagrangian stochastic (bLs) model; and second, by comparing the emission rates of a control plot obtained from the footprint analysis method and from the "backward" simulation of the bLs model. It is found that the analytical footprint fractions compare well with the values obtained from the bLs model (correlation coefficient of 0.58 and 0.66 within p value <0.001). An average of 4.3 % of the measured fluxes is found to be contributed by sources outside the measured area and, excluding this outside area contribution to the measured flux, footprint corrected emission rates within the defined domain are found to increase by 2.1 to 5.8 % of the measured flux. Also, the proposed method of emission rate estimation is found to work well under a wide range of atmospheric stability. PMID:24899395

  7. CO2 and N2O emissions from Lou soils of greenhouse tomato fields under aerated irrigation

    NASA Astrophysics Data System (ADS)

    Hou, Huijing; Chen, Hui; Cai, Huanjie; Yang, Fan; Li, Dan; Wang, Fangtong

    2016-05-01

    The change of O2 content in soil caused by aerated irrigation (AI) must inevitably affect the production and emissions of CO2 and N2O from soils. This paper described in-situ observation of CO2 and N2O emissions from AI soils with static chamber-GC technique, in order to reveal the effects of AI on CO2 and N2O emissions from soils of greenhouse tomato fields in autumn-winter season. CO2 and N2O emissions from AI soils mainly concentrated in the blooming and fruit setting period compared to other periods. AI increased cumulative emissions of CO2 and N2O by 11.8% (p = 0.394) and 10.0% (p = 0.480), respectively, compared to the control. The integrative global warming potential of CO2 and N2O on a 100-year horizon for the AI treatment was 6430.60 kg ha-1, increased by 11.7% compared with that for the control (p = 0.356). Both the emissions of CO2 and N2O from AI soils had the exponential positive correlation with soil water-filled pore space (WFPS). The highest peak of CO2 and N2O fluxes from AI soils was observed at 46.7% and 47.5% WFPS, with WFPS ranging from 43.3% to 51.5% and from 45.6% to 52.3% during the whole growth stage, respectively. In addition, the average yield for the AI treatment (34.52 t ha-1) was significantly greater (17.4%) compared with that of the control (p = 0.018). These results suggest that AI do not significantly increase the integrative greenhouse effect caused by CO2 and N2O from soils of greenhouse tomato fields, but significantly increase the tomato yield. The research results provide certain theoretical foundation and scientific basis for accurately evaluating the farmland ecological effect of AI technique.

  8. CO2 and N2O emissions from Lou soils of greenhouse tomato fields under aerated irrigation

    NASA Astrophysics Data System (ADS)

    Hou, Huijing; Chen, Hui; Cai, Huanjie; Yang, Fan; Li, Dan; Wang, Fangtong

    2016-05-01

    The change of O2 content in soil caused by aerated irrigation (AI) must inevitably affect the production and emissions of CO2 and N2O from soils. This paper described in-situ observation of CO2 and N2O emissions from AI soils with static chamber-GC technique, in order to reveal the effects of AI on CO2 and N2O emissions from soils of greenhouse tomato fields in autumn-winter season. CO2 and N2O emissions from AI soils mainly concentrated in the blooming and fruit setting period compared to other periods. AI increased cumulative emissions of CO2 and N2O by 11.8% (p = 0.394) and 10.0% (p = 0.480), respectively, compared to the control. The integrative global warming potential of CO2 and N2O on a 100-year horizon for the AI treatment was 6430.60 kg ha-1, increased by 11.7% compared with that for the control (p = 0.356). Both the emissions of CO2 and N2O from AI soils had the exponential positive correlation with soil water-filled pore space (WFPS). The highest peak of CO2 and N2O fluxes from AI soils was observed at 46.7% and 47.5% WFPS, with WFPS ranging from 43.3% to 51.5% and from 45.6% to 52.3% during the whole growth stage, respectively. In addition, the average yield for the AI treatment (34.52 t ha-1) was significantly greater (17.4%) compared with that of the control (p = 0.018). These results suggest that AI do not significantly increase the integrative greenhouse effect caused by CO2 and N2O from soils of greenhouse tomato fields, but significantly increase the tomato yield. The research results provide certain theoretical foundation and scientific basis for accurately evaluating the farmland ecological effect of AI technique.

  9. Mechanistic approach to understand increased N2O emission followed by biochar application to the organic poor field soil

    NASA Astrophysics Data System (ADS)

    Yoo, G.; Lee, Y.; Seo, J.; Kim, J.; Kim, Y.

    2015-12-01

    Biochar, which is a by-product of pyrolysis, is widely accepted as a climate change mitigation strategy if it is applied to soils. A lot of researches have reported that application of biochar reduced the emission of N2O due to better aeration and increased pH. However, in the dry, organic poor, and heavily fertilized Korean field soil, we observed rather an increase in N2O emission in our previous researches. To explain this inconsistent trend, we conducted a research investigating the mechanisms of N2O emission. The main mechanisms of N2O emission from soils are nitrification and denitrification, among which we exclude the possibility of denitrification process because the soil water condition at our sampling dates was dry. To confirm our assumption that the increased N2O emission from the soil is mainly from the enhanced nitrification due to biochar addition, we used the nitrification inhibitor (DCD: Dicyandiamide). The experiment was performed in the pepper field located in Gyeonggi-do, Korea where we already observed an increase in N2O emission followed by biochar amendment in the previous year. Treatments include the control, biochar treatment (BC, 2 ton ha-1), DCD treatment (DCD, 10% of N fertilizer w/w), and biochar and DCD co-treatment (BC+DCD). All the treatments were received with N:P2O5:K2O (225 : 112 : 149 kg ha-1). Daily average of N2O emission rate was increased in the BC treatment by 154% and the emission was reduced to the control level in the BC+DCD treatment. From this result, we could confirm that the increased N2O emission from the biochar application is from the nitrification process. The field experiment will be prolonged to Aug 2015 and for the further analysis, the basic soil physicochemical parameters (TC, TN, pH, hot water extractable C, available N) and microbial parameters (fluorescein diacetate hydrolysis assay, microbial biomass C, and assay of nitrifiers) will be measured.

  10. Post-harvest N2O emissions were not affected by various types of oilseed straw incorporated into soil

    NASA Astrophysics Data System (ADS)

    Köbke, Sarah; Senbayram, Mehmet; Hegewald, Hannes; Christen, Olaf; Dittert, Klaus

    2015-04-01

    Oilseed rape post-harvest N2O emissions are seen highly critical as so far they are considered as one of the most crucial drawbacks in climate-saving bioenergy production systems. N2O emissions may substantially counterbalance the intended savings in CO2 emissions. Carbon-rich crop residues in conjunction with residual soil nitrate are seen as a key driver since they may serve as energy source for denitrification and, they may alter soil-borne N2O emissions. As oilseed rape straw is known to have high N/C ratio compared to other crop residues, its soil incorporation may specifically trigger post-harvest N2O emissions. Therefore, the aim of the present study was to determine post-harvest N2O emissions in soils amended with various types of oilseed rape straw (with different N/C ratio) and barley straw in field and incubation experiments. In the incubation experiment, oilseed rape or 15N labelled barley straw were mixed with soil at a rate of 1.3 t DM ha-1 and studied for 43 days. Treatments consisted of non-treated control soil (CK), 15N labelled barley straw (BST), oilseed rape straw (RST), 15N labelled barley straw + N (BST+N), or oilseed rape straw + N (RST+N). N fertilizer was applied to the soil surface as ammonium-nitrate at a rate of 100 kg N ha-1 and soil moisture was adjusted to 80% water-holding capacity. In the field experiment, during the vegetation period 15N labelled fertilizer (15NH415NO3) was used to generate 15N labelled oilseed rape straw (up to 5 at%). Here, the three fertilizer treatments consisted of 5 kg N ha-1 (RST-5), 150 kg N ha-1 (RST-150) and 180 kg N ha-1 (RST-180). Post-harvest N2O emissions were determined during the period of August 2013 to February 2014 by using static flux chambers. In the incubation trial, cumulative N2O emissions were 5, 29, 40 g N2O-N ha-1 148 days-1 in non-fertilized control, BST and RST treatments, respectively. Here, emissions were slightly higher in RST than BST (p

  11. Influence of short-term transfers on nitrogen fluxes, budgets and indirect N2O emissions in rural landscapes

    NASA Astrophysics Data System (ADS)

    Duretz, S.; Drouet, J.-L.; Durand, P.; Cellier, P.

    2011-08-01

    Spatial interactions at short-term may lead to large inputs of reactive nitrogen (Nr) to oligotrophic ecosystems and induce environmental threats such as additional N2O emissions and global warming. The paper presents a new methodology to estimate Nr fluxes, especially additional N2O emissions, at the landscape scale by taking into account spatial interactions between landscape elements. We used the NitroScape model which integrates processes of Nr transformation and short-term transfer in a dynamic and spatially distributed way to simulate Nr fluxes and budgets at the landscape scale. Four configurations of NitroScape were implemented by taking into account or not the atmospheric, hydrological or both pathways of Nr transfer. We simulated Nr fluxes, especially direct and indirect N2O emissions, within a test landscape including pig farms, croplands and unmanaged ecosystems. Simulation results showed the ability of NitroScape to simulate patterns of Nr losses and recapture for each landscape element and the whole landscape. They made it possible to quantify the contribution of both atmospheric and hydrological transfers in Nr fluxes and budgets. Indirect N2O emissions were estimated at almost 25 % of the total N2O emissions. They varied within the landscape according to land use, meteorological and soil conditions as well as topography. This first attempt has proved that the NitroScape model is a useful tool to estimate the effect of spatial interactions on Nr fluxes and budgets as well as indirect N2O emissions within landscapes. Our approach needs to be further tested by applying NitroScape to several spatial distributions of ecosystems within the landscape and to real and larger landscapes.

  12. [N2O emission from an intensively managed greenhouse vegetable field in Nanjing suburb, Jiangsu Province of East China].

    PubMed

    Jia, Jun-Xiang; Zhang, Man; Xiong, Zheng-Qin; Li, Ye

    2012-03-01

    By using static opaque chamber and gas chromatography, this paper studied the dynamic changes of N2O fluxes and their relationships with soil temperature, soil moisture content, and soil nitrate and ammonium contents in an intensively managed greenhouse celery-Tung choy-Bok choy-amaranth rotation field and in a bare fallow land in Nanjing suburb. The cumulative N2O emission from the rotation vegetable field was as high as 137.2 kg N x hm(-2), being significantly higher than that from the bare fallow land (29.2 kg N x hm(-2)), and the N2O-N emission factor of the rotation vegetable field ecosystem was up to 4.6%. In the rotation field, the planting of Tung choy had the greatest contribution to the annual cumulative N2O emission, occupying 53.5% of the total, followed by the planting of Bok choy (31.9%), celery field (4.5%), and amaranth (4.8%). The N2O flux of the rotation field had significant positive correlation with soil temperature, the Q10 being 2.80, but no significant correlations with soil moisture content and soil nitrate and ammonium contents. PMID:22720619

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

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

  14. Comparison of three models for simulating N2O emissions from paddy fields under water-saving irrigation

    NASA Astrophysics Data System (ADS)

    Wu, Xiarui; Zhang, Ao

    2014-12-01

    N2O emissions simulated by WNMM, DAYCENT and Crop-DNDC models were compared to the observed data sets from rice-wheat rotation systems under water-saving irrigation at Kunshan City, Jiangsu Province, China. On the basis of the correlation and paired t-test for evaluation, the simulation of N2O emission by Crop-DNDC and WNMM models provided better agreement with the observed data than by DAYCENT model. The daily time step, Crop-DNDC model was consistently the best for predicting daily N2O emissions (R2 = 0.892, n = 28, p > 0.05), and WNMM model performed better (R2 = 0.87, n = 28, p > 0.05). The Crop-DNDC model simulated the seasonal cumulative N2O emissions were the closest to the measured value of 1.07 kg N ha-1, and WNMM and DAYCENT models predicted 8.4% and 15.0% more N2O emissions than that in field experiments. The three models predicted well the seasonal cycle of soil temperature, soil moisture and could provide reliable estimations. The simulation of daily average soil temperature at 10 cm were consistently with the field observed data, which by Crop-DNDC (R2 = 0.92, n = 67, p > 0.05) and WNMM (R2 = 0.91, n = 67, p > 0.05). The comparison of observed to simulated results indicated that soil WFPS was simulated by Crop-DNDC (R2 = 0.52, n = 50, p > 0.05), WNMM (R2 = 0.56, n = 50, p > 0.05) and DAYCENT (R2 = 0.37, n = 50, p > 0.05). Accurate simulation of soil moisture, soil temperature and accurate partitioning of gaseous nitrogen loss into NO, N2O and N2 are challenges for all models.

  15. N2O emissions from activated sludge processes, 2008-2009: results of a national monitoring survey in the United States.

    PubMed

    Ahn, Joon Ho; Kim, Sungpyo; Park, Hongkeun; Rahm, Brian; Pagilla, Krishna; Chandran, Kartik

    2010-06-15

    Despite recognition of the possible role of biological nitrogen removal (BNR) processes in nitrous oxide (N(2)O) emission, a measured database of N(2)O emissions from these processes at the national scale does not currently exist. This study focused on the quantification of N(2)O emissions at 12 wastewater treatment plants (WWTPs) across the United States using a newly developed U.S. Environmental Protection Agency (USEPA) reviewed protocol. A high degree of variability in field-scale measurements of N(2)O was observed, both across the WWTPs sampled and within each WWTP. Additionally, aerobic zones, which have hitherto not been considered in the USEPA approach of estimating N(2)O emissions, generally contributed more to N(2)O fluxes than anoxic zones from BNR reactors. These results severely qualify the conventional use of a single emission factor to "estimate" N(2)O emissions from BNR processes, solely by virtue of denitrification. Upon subjecting the nationwide data set to multivariate regression data mining, high nitrite, ammonium, and dissolved oxygen concentrations were positively correlated with N(2)O emissions from aerobic zones of activated sludge reactors. On the other hand, high nitrite and dissolved oxygen concentrations were positively correlated with N(2)O emissions from anoxic zones. Based on these results, it can be argued that activated sludge processes that minimize transient or permanent build up of ammonium or nitrite, especially in the presence of dissolved oxygen, are expected to have low N(2)O emissions. PMID:20465250

  16. Optimum sampling time and frequency for measuring N2O emissions from a rain-fed cereal cropping system.

    PubMed

    Reeves, Steven; Wang, Weijin

    2015-10-15

    Annual cumulative nitrous oxide (N2O) emissions from soil have historically been calculated from intermittent data measured manually via the static chamber method. The temporal variability in emissions, both diurnally and between days, introduces uncertainty into the up-scaling of static chamber data. This study assessed the most appropriate time of the day to sample and the best sampling frequency to ensure reliable estimates of annual cumulative emissions. Sub-daily N2O emissions were measured using automatic gas sampling chambers over three years in a sub-tropical cereal crop system. The sub-daily dataset was divided into eight time periods per day to assess the best sampling time of the day. Daily mean N2O emissions were subsampled from the dataset to simulate different sampling frequencies, including pre-set and rainfall-based scenarios. Annual cumulative N2O emissions were calculated for these scenarios and compared to the 'actual' annual cumulative emissions. The results demonstrated that manual sampling between mid-morning (09:00) and midday (12:00), and late evening (21:00) and midnight (24:00) best approximated the daily mean N2O emission. Factoring in the need to sample during daylight hours, gas sampling from mid-morning to midday was the most appropriate sampling time. Overall, triweekly sampling provided the most accurate estimate (± 4% error) of annual cumulative N2O emissions, but was undesirable due to its labour intensive high sampling frequency. Weekly sampling with triweekly sampling in the two weeks following rainfall events was the most efficient sampling schedule, as it had similar accuracy (± 5% error) to the triweekly sampling, the smallest variability in outcomes and approximately half the sampling times of triweekly sampling. Inter-annual rainfall variability affected the accuracy and variability of estimations of annual cumulative emissions, but did not affect the overall trends in sampling frequency accuracy. This study demonstrated

  17. [Effects of L-methionine on nitrification and N2O emission in subtropical forest soil].

    PubMed

    Lin, Wei; Pei, Guang-ting; Ma, Hong-liang; Gao, Ren; Yin, Yun-feng; Peng, Yuan-zhen

    2015-09-01

    The objective of this study was to investigate the influence of L-methionine on nitrification and nitrous oxide emission in a red soil under laboratory incubation experiments. A subtropical broad-leaved forest soil sample was collected from Wanmulin natural reserve in Fujian Province, Southeast China. Five treatments were carried out with three replications, i. e., control (CK), L- methionine addition (M), L-methionine and NH(4+)-N addition (MA), L-methionine and NO(2-)-N addition (MN), L-methionine and glucose addition (MC). The soil moisture was maintained at 60% WHC or 90% WHC. The results indicated that the soil NH(4+)-N content in the M treatment significantly increased by 0.8%-61.3%, while the soil NO(3-)-N content reduced by 13.2%-40.7% compared with CK. Under 60% WHC condition, soil NO(2-)-N content in the MC treatment was higher than in the M treatment, soil NO(3-)-N content in the MA and MN treatments were greater than that in the M treatment, and greater in the MN treatment than in the MA treatment. The soil NO(3-)-N content was lowest in the M treatment after incubation. These results suggested that L-methionine could inhibit nitrosation process of autotrophic nitrification. To some extent, carbon addition as glucose with L-methionine decreased the NH(4+)-N content, inhibited the autotrophic nitrification and their effects were dependent on water level. Under 90% WHC condition, carbon addition improved denitrification more obviously, but the decrease of NO(3-)-N content was not sufficient to prove the inhibition of hetero-nitrification due to carbon addition in the presence of L-methionine. The nitrous oxide emission from soil was increased by L-methionine addition. Compared with 60% WHC condition, the nitrous oxide emission was higher under 90% WHC condition, and the promotion of L-methionine addition on N2O was greater when glucose added. PMID:26785545

  18. Legumes or nitrification inhibitors to reduce N2O emissions in subtropical cereal cropping systems? A simulation study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The DAYCENT biogeochemical model was used to investigate how the use of fertilisers coated with nitrification inhibitors and the introduction of legumes in the crop rotation can affect subtropical cereal production and N2O emissions. The model was validated using comprehensive multi-seasonal, high-f...

  19. Modelling site-specific N2O emission factors from Austrian agricultural soils for targeted mitigation measures (NitroAustria)

    NASA Astrophysics Data System (ADS)

    Amon, Barbara; Zechmeister-Boltenstern, Sophie; Kasper, Martina; Foldal, Cecilie; Schiefer, Jasmin; Kitzler, Barbara; Schwarzl, Bettina; Zethner, Gerhard; Anderl, Michael; Sedy, Katrin; Gaugitsch, Helmut; Dersch, Georg; Baumgarten, Andreas; Haas, Edwin; Kiese, Ralf

    2016-04-01

    Results from a previous project "FarmClim" highlight that the IPCC default emission factor is not able to reflect region specific N2O emissions from Austrian arable soils. The methodology is limited in identifying hot spots and hot moments of N2O emissions. When estimations are based on default emission factors no recommendations can be given on optimisation measures that would lead to a reduction of soil N2O emissions. The better the knowledge is about Nitrogen and Carbon budgets in Austrian agricultural managed soils the better the situation can be reflected in the Austrian GHG emission inventory calculations. Therefore national and regionally modelled emission factors should improve the evidence for national deviation from the IPCC default emission factors and reduce the uncertainties. The overall aim of NitroAustria is to identify the drivers for N2O emissions on a regional basis taking different soil types, climate, and agricultural management into account. We use the LandscapeDNDC model to update the N2O emission factors for N fertilizer and animal manure applied to soils. Key regions in Austria were selected and region specific N2O emissions calculated. The model runs at sub-daily time steps and uses data such as maximum and minimum air temperature, precipitation, radiation, and wind speed as meteorological drivers. Further input data are used to reflect agricultural management practices, e.g., planting/harvesting, tillage, fertilizer application, irrigation and information on soil and vegetation properties for site characterization and model initialization. While at site scale, arable management data (crop cultivation, rotations, timings etc.) is obtained by experimental data from field trials or observations, at regional scale such data need to be generated using region specific proxy data such as land use and management statistics, crop cultivations and yields, crop rotations, fertilizer sales, manure resulting from livestock units etc. The farming

  20. Potential impact of atmospheric N deposition on soil N2O emission varies with different soil N regimes

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Yi, M.; Koike, T.

    2011-12-01

    Future increases in nitrogen (N) deposition has the potential to change belowground nutrient dynamics, especially N cycle, and thereby can alter the soil-atmosphere exchange of nitrous oxide (N2O) which is one of the major greenhouse gases. Moreover, we considered that their effect on soil N2O emission varies with different soil N levels because N2O is a by-product of the biological nitrification process in aerobic soil environments and of the biological denitrification process in anaerobic soil environments. To understand the changes in soil N2O flux under different soil N, we carried out simulated N addition experiment in three-year-old hybrid larch F1 (F1: Larix gmelinii var. japonica × Larix kaempferi) plantation during two growing seasons 2008 - 2009. The hybrid larch F1 was developed to make up for several problems of larch species, e.g. a high susceptibility to disease or grazing damage by insects and fungi, and a large number of this seedlings are planted recently in northern Japan. Based on soil analysis, we selected two sites which have different soil N concentration, i.e. low-N and high-N concentrations. Nitrogen input was initiated at the onset of our experiment, and included four treatments with four replications: Low-N soil + Zero-N control, Low-N soil + 50 kg-N addition, High-N soil + Zero-N control and High-N soil + 50 kg-N addition. The N was added as ammonium nitrate (NH4NO3) solution distributed in four occasions during each growing season. Gas and soil samples were taken from each plot on ten occasions at a time during each growing season. Collected N2O concentrations were determined by a gas chromatograph (GC-14B; Shimadzu, Kyoto, Japan) equipped with an electron capture detector, while total-N and inorganic-N concentrations were obtained by a NC analyzer (Sumigraph NC-1000; Sumica Chemical Analysis Service Ltd., Osaka, Japan) and an auto analyzer (AACS-4; BL-TEC Inc., Osaka, Japan), respectively. Before the N addition, initial total-N in High

  1. N2O and N2 emissions from contrasting soil environments - interactive effects of soil nitrogen, hydrology and microbial communities

    NASA Astrophysics Data System (ADS)

    Christiansen, Jesper; Elberling, Bo; Ribbons, Relena; Hedo, Javier; José Fernández Alonso, Maria; Krych, Lukasz; Sandris Nielsen, Dennis; Kitzler, Barbara

    2016-04-01

    Reactive nitrogen (N) in the environment has doubled relative to the natural global N cycle with consequences for biogeochemical cycling of soil N. Also, climate change is expected to alter precipitation patterns and increase soil temperatures which in Arctic environments may accelerate permafrost thawing. The combination of changes in the soil N cycle and hydrological regimes may alter microbial transformations of soil N with unknown impacts on N2O and N2 emissions from temperate and Arctic soils. We present the first results of soil N2O and N2 emissions, chemistry and microbial communities over soil hydrological gradients (upslope, intermediate and wet) across a global N deposition gradient. The global gradient covered an N-limited high Arctic tundra (Zackenberg-ZA), a pacific temperate rain forest (Vancouver Island-VI) and an N saturated forest in Austria (Klausenleopoldsdorf-KL). The N2O and N2 emissions were measured from intact cores at field moisture in a He-atmosphere system. Extractable NH4+ and NO3-, organic and microbial C and N and potential enzyme-activities were determined on soil samples. Soil genomic DNA was subjected to MiSeq-based tag-encoded 16S rRNA and ITS gene amplicon sequencing for the bacterial and fungal community structure. Similar soil moisture levels were observed for the upslope, intermediate and wet locations at ZA, VI and KL, respectively. Extractable NO3- was highest at the N rich KL and lowest at ZA and showed no trend with soil moisture similar to NH4+. At ZA and VI soil NH4+ was higher than NO3- indicating a tighter N cycling. N2O emissions increased with soil moisture at all sites. The N2O emissions for the wet locations ranked similarly to NO3- with the largest response to soil moisture at KL. N2 emissions were remarkably similar across the sites and increased with soil wetness. Microbial C and N also increased with soil moisture and were overall lowest at the N rich KL site. The potential activity of protease enzyme was site

  2. Genetic potential for N2O emissions from the sediment of a free water surface constructed wetland.

    PubMed

    García-Lledó, Arantzazu; Vilar-Sanz, Ariadna; Trias, Rosalia; Hallin, Sara; Bañeras, Lluís

    2011-11-01

    Removal of nitrogen is a key aspect in the functioning of constructed wetlands. However, incomplete denitrification may result in the net emission of the greenhouse gas nitrous oxide (N(2)O) resulting in an undesired effect of a system supposed to provide an ecosystem service. In this work we evaluated the genetic potential for N(2)O emissions in relation to the presence or absence of Phragmites and Typha in a free water surface constructed wetland (FWS-CW), since vegetation, through the increase in organic matter due to litter degradation, may significantly affect the denitrification capacity in planted areas. Quantitative real-time PCR analyses of genes in the denitrification pathway indicating capacity to produce or reduce N(2)O were conducted at periods of different water discharge. Genetic potential for N(2)O emissions was estimated from the relative abundances of all denitrification genes and nitrous oxide reductase encoding genes (nosZ). nosZ abundance was invariably lower than the other denitrifying genes (down to 100 fold), and differences increased significantly during periods of high nitrate loads in the CW suggesting a higher genetic potential for N(2)O emissions. This situation coincided with lower nitrogen removal efficiencies in the treatment cell. The presence and the type of vegetation, mainly due to changes in the sediment carbon and nitrogen content, correlated negatively to the ratio between nitrate and nitrite reducers and positively to the ratio between nitrite and nitrous oxide reducers. These results suggest that the potential for nitrous oxide emissions is higher in vegetated sediments. PMID:21920580

  3. Development of an Open-Path N2O Flux Measurement System for Understanding Agricultural and Soil Emissions

    NASA Astrophysics Data System (ADS)

    Gomez, A.; Silver, J.; Massick, S.; Ochoa, E.; Stanton, A. C.

    2015-12-01

    Nitrous oxide is the third most important greenhouse gas, with an atmospheric lifetime of ~114 years and a global warming impact ~300 times greater than that of CO2. The main cause of nitrous oxide's atmospheric increase is anthropogenic emissions, and over 80% of the current global anthropogenic flux is related to agriculture, including associated land-use change. An accurate assessment of N2O emissions from agriculture is vital not only for understanding the global N2O balance and its impact on climate and also for designing crop systems with lower GHG emissions. This work focuses on the early development of an open path N2O instrument for field deployment, based on quantum cascade laser absorption. With a targeted precision of 0.1 ppb at 10 Hz, this instrument will enable eddy covariance measurements to determine vertical fluxes of N2O. Details of the instrument design, which emphasizes ruggedness and high thermal stability, will be presented along with initial results from outdoor testing of the instrument.

  4. Intergenomic Comparisons Highlight Modularity of the Denitrification Pathway and Underpin the Importance of Community Structure for N2O Emissions

    PubMed Central

    Graf, Daniel R. H.; Jones, Christopher M.; Hallin, Sara

    2014-01-01

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

  5. Effects of agricultural practices on greenhouse gas emissions (N2O, CH4 and CO2) from corn fields

    NASA Astrophysics Data System (ADS)

    Hui, D.; Wang, J.; Jima, T.; Dennis, S.; Stockert, C.; Smart, D.; Bhattarai, S.; Brown, K.; Sammis, T.; Reddy, C.

    2012-12-01

    The United States is, by far, the largest producer of corn (Zea mays L.) in the world. Recent increases in fertilizer cost and concerns over global climate change have farmers and others interested in more efficient fertilization management and greenhouse gas emissions reductions. To seek the best management practices, we conducted field experiments during the 2012 growing season at Tennessee State University Agricultural Research and Demonstration Center in Nashville, TN. Six treatments were applied including regular URAN application [2 times], multiple URAN applications [4 times], denitrification inhibitor with regular URAN application, and chicken litter plus regular URAN application in no-tilled plots, and URAN application plus bio-char in tilled plots, all compared to regular URAN application in conventional tilled plots. Each treatment was replicated six times (blocks). We measured N2O, CO2 and CH4 emissions using a closed chamber method after rainfall events, fertilizer applications or every two weeks whichever was shorter. Corresponding soil NH4+-N and NO3--N, soil temperature and moisture were also measured during the gas sampling. Plant physiology and growth were measured about every two weeks. While preliminary results indicate that N2O and CO2 fluxes were significantly influenced by the agricultural practices on some days, particularly after rainfall events, CH4 flux was not influenced by the treatments during most of the days. Plots with bio-char showed significantly lower N2O emissions. We also measured N2O flux in a commercial corn field using the Eddy Covariance (EC) technique to ground verify the chamber based N2O emissions at the field scale. Results obtained with the EC technique seem comparable with the chamber method.

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

    PubMed

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

    2016-05-01

    The optimization of operation parameters is a key consideration to minimize nitrous oxide (N2O) emissions in biological nitrogen removal processes. So far, different parameters have only been investigated individually, making it difficult to compare their specific effects and combined influences. In this study, we applied the Plackett-Burman (PB) multifactorial experimental design and response surface methodology (RSM) analysis to find the optimized condition for the mitigation of N2O release in a nitrifying granular sludge system. Seven parameters (temperature, pH, feeding strategy, C/N ratio, aeration rate, Cu(2+) concentration, and aeration mode) were tested in parallel. Five of them (other than chemical oxygen demand/nitrogen (C/N) ratio and Cu(2+) concentration) were selected as influential factors. Since the type of feeding strategies and aeration modes cannot be quantified, continuous feed strategy and anoxic/oxic aeration mode were applied for the following study. Influences of temperature, pH, and aeration rate on N2O emissions were tested with RSM analysis to further investigate the mutual interactions among the parameters and to identify the optimal values that would minimize N2O release. Results showed the minimum emission value could be obtained under the temperature of 22.3 °C, pH of 7.1 and aeration rate of 0.20 m(3)/h. Predicted results were then verified by subsequent validation experiments. The estimated N2O emission value of each design by RSM was also observed in good relationships with experimental result. PMID:26841778

  7. Global N2O cycles--terrestrial emissions, atmospheric accumulation and biospheric effects.

    PubMed

    Banin, A; Lawless, J G; Whitten, R C

    1984-01-01

    Tropospheric nitrous oxide concentration has increased by 0.2-0.4% per year over the period 1975 to 1982, amounting to net addition to the atmosphere of 2.8-5.6 Tg N2O-N per year. This perturbation, if continued into the future, will affect stratospheric chemical cycles, and the thermal balance of the Earth. In turn it will have direct and indirect global effects on the biosphere. Though the budget and cycles of N2O on Earth are not yet fully resolved, accumulating information and recent modelling efforts enable a more complete evaluation and better definition of gaps in our knowledge. PMID:11537777

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

    NASA Astrophysics Data System (ADS)

    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

  9. Wet-season spatial variability in N2O emissions from a tea field in subtropical central China

    NASA Astrophysics Data System (ADS)

    Fu, X.; Liu, X.; Li, Y.; Shen, J.; Wang, Y.; Zou, G.; Li, H.; Song, L.; Wu, J.

    2015-06-01

    Tea fields emit large amounts of nitrous oxide (N2O) to the atmosphere. Obtaining accurate estimations of N2O emissions from tea-planted soils is challenging due to strong spatial variability. We examined the spatial variability in N2O emissions from a red-soil tea field in Hunan Province, China, on 22 April 2012 (in a wet season) using 147 static mini chambers approximately regular gridded in a 4.0 ha tea field. The N2O fluxes for a 30 min snapshot (10:00-10:30 a.m.) ranged from -1.73 to 1659.11 g N ha-1 d-1 and were positively skewed with an average flux of 102.24 g N ha-1 d-1. The N2O flux data were transformed to a normal distribution by using a logit function. The geostatistical analyses of our data indicated that the logit-transformed N2O fluxes (FLUX30t) exhibited strong spatial autocorrelation, which was characterized by an exponential semivariogram model with an effective range of 25.2 m. As observed in the wet season, the logit-transformed soil ammonium-N (NH4Nt), soil nitrate-N (NO3Nt), soil organic carbon (SOCt) and total soil nitrogen (TSNt) were all found to be significantly correlated with FLUX30t (r = 0.57-0.71, p < 0.001). Three spatial interpolation methods (ordinary kriging, regression kriging and cokriging) were applied to estimate the spatial distribution of N2O emissions over the study area. Cokriging with NH4Nt and NO3Nt as covariables (r = 0.74 and RMSE = 1.18) outperformed ordinary kriging (r = 0.18 and RMSE = 1.74), regression kriging with the sample position as a predictor (r = 0.49 and RMSE = 1.55) and cokriging with SOCt as a covariable (r = 0.58 and RMSE = 1.44). The predictions of the three kriging interpolation methods for the total N2O emissions of 4.0 ha tea field ranged from 148.2 to 208.1 g N d-1, based on the 30 min snapshots obtained during the wet season. Our findings suggested that to accurately estimate the total N2O emissions over a region, the environmental variables (e.g., soil properties) and the current land use pattern

  10. Wet-season spatial variability of N2O emissions from a tea field in subtropical central China

    NASA Astrophysics Data System (ADS)

    Fu, X.; Liu, X.; Li, Y.; Shen, J.; Wang, Y.; Zou, G.; Li, H.; Song, L.; Wu, J.

    2015-01-01

    Tea fields emit large amounts of nitrous oxide (N2O) to the atmosphere. Obtaining accurate estimations of N2O emissions from tea-planted soils is challenging due to strong spatial variability. We examined the spatial variability of N2O emissions from a red-soil tea field in Hunan province, China, on 22 April 2012 (in a wet season) using 147 static mini chambers approximately regular gridded in a 4.0 ha tea field. The N2O fluxes for a 30 min snapshot (10-10.30 a.m.) ranged from -1.73 to 1659.11 g N ha-1 d-1 and were positively skewed with an average flux of 102.24 g N ha-1 d-1. The N2O flux data were transformed to a normal distribution by using a logit function. The geostatistical analyses of our data indicated that the logit-transformed N2O fluxes (FLUX30t) exhibited strong spatial autocorrelation, which was characterized by an exponential semivariogram model with an effective range of 25.2 m. As observed in the wet season, the logit-transformed soil ammonium-N (NH4Nt), soil nitrate-N (NO3Nt), soil organic carbon (SOCt), total soil nitrogen (TSNt) were all found to be significantly correlated with FLUX30t (r=0.57-0.71, p<0.001). Three spatial interpolation methods (ordinary kriging, regression kriging and cokriging) were applied to estimate the spatial distribution of N2O emissions over the study area. Cokriging with NH4Nt and NO3Nt as covariables (r= 0.74 and RMSE =1.18) outperformed ordinary kriging (r= 0.18 and RMSE =1.74), regression kriging with the sample position as a predictor (r= 0.49 and RMSE =1.55) and cokriging with SOCt as a covariable (r= 0.58 and RMSE =1.44). The predictions of the three kriging interpolation methods for the total N2O emissions of the 4.0 ha tea field ranged from 148.2 to 208.1 g N d-1, based on the 30 min snapshots obtained during the wet season. Our findings suggested that to accurately estimate the total N2O emissions over a region, the environmental variables (e.g., soil properties) and the current land use pattern (e.g., tea

  11. 40 CFR Table Aa-1 to Subpart Aa of... - Kraft Pulping Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... for Biomass-Based CO2, CH4, and N2O AA Table AA-1 to Subpart AA of Part 98 Protection of Environment... Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O Wood furnish Biomass-based emissions factors(kg/mmBtu HHV) CO2 a CH4 N2O North American Softwood 94.4 0.030 0.005 North American Hardwood...

  12. Effect of fertilization on N2O emissions from a marginal soil used for perennial grass bioenergy production

    NASA Astrophysics Data System (ADS)

    Stoof, Cathelijne; Karim, Imtiaz; Mason, Cedric; Tadipatri, Dhanya; Cary, Ian; Crawford, Ryan; Hansen, Julie; Crawford, Jamie; Mayton, Hilary; Steenhuis, Tammo; Richards, Brian

    2014-05-01

    Marginal lands constitute the primary land base available for development of bioenergy feedstocks in New York and the northeastern USA. Many of these soils are marginal because seasonal wetness prevents profitable row crop cultivation, but they are potentially suitable for perennial bioenergy feedstocks like switchgrass. Using these frequently wet soils for bioenergy production has multiple environmental and socio-economic benefits, yet little is known about how sustainable this practice is regarding greenhouse gas emissions - particularly in relation to the application of fertilizers. In a 2.2-ha field study near Ithaca, NY, USA, we are therefore monitoring greenhouse gas production from marginal silty clay loam soils cultivated with switchgrass. Here, we present results of our 2013 monitoring campaign, in which we assessed the effect of surface-applied granular ammonium sulfate-fertilizer (0, 56 and 112 kg N/ha) on N2O emissions along a natural catena from organic matter-rich wet lowland soil to drier midslope and upslope soils with higher rock fragment content. Sampling was done at 1 /2-week intervals around fertilization in June extending to 3-week intervals around harvest in September, giving a total of 15 sampling events. Emissions were sampled in a factorial design using four replicate static chambers per plot, and soil moisture, soil temperature and perched water table depth was assessed likewise. As expected, N2O emissions increased with N-fertilizer application. This effect of fertilization was much stronger than the effect of soil type or slope position. The greatest N2O fluxes were observed a few days after fertilization; we will explore and present the effects of rainfall, air temperature, soil moisture and soil temperature as potential drivers of smaller peaks occurring post-fertilization. Since the non-fertilized plots had negligible N2O emissions while still producing switchgrass at 6 Mg/ha, unfertilized switchgrass production is naturally most

  13. Effect of different agronomic practises on greenhouse gas emissions, especially N2O and nutrient cycling

    NASA Astrophysics Data System (ADS)

    Koal, Philipp; Schilling, Rolf; Gerl, Georg; Pritsch, Karin; Munch, Jean Charles

    2014-05-01

    In order to achieve a reduction of greenhouse gas emissions, management practises need to be adapted by implementing sustainable land use. At first, reliable field data are required to assess the effect of different farming practises on greenhouse gas budgets. The conducted field experiment covers and compares two main aspects of agricultural management, namely an organic farming system and an integrated farming system, implementing additionally the effects of diverse tillage systems and fertilisation practises. Furthermore, the analysis of the alterable biological, physical and chemical soil properties enables a link between the impact of different management systems on greenhouse gas emissions and the monitored cycle of matter, especially the nitrogen cycle. Measurements were carried out on long-term field trials at the Research Farm Scheyern located in a Tertiary hilly landscape approximately 40 km north of Munich (South Germany). The long-term field trials of the organic and integrated farming system were started in 1992. Since then, parcels in a field (each around 0,2-0,4 ha) with a particular interior plot set-up have been conducted. So the 20 years impacts of different tillage and fertilisation practises on soil properties including trace gases were examined. Fluxes of CH4, N2O and CO2 are monitored since 2007 for the integrated farming system trial and since 2012 for the organic farming system trial using an automated system which consists of chambers (per point: 4 chambers, each covering 0,4 m2 area) with a motor-driven lid, an automated gas sampling unit, an on-line gas chromatographic analysis system, and a control and data logging unit (Flessa et al. 2002). Each chamber is sampled 3-4 times in 24 hours. The main outcomes are the analysis of temporal and spatial dynamics of greenhouse gas fluxes as influenced by management practice events (fertilisation and tillage) and weather effects (drying-rewetting, freezing-thawing, intense rainfall and dry periods

  14. High resolution, balloon-borne emission spectroscopy of trace species in the lower stratosphere - N2O5, HNO3

    NASA Technical Reports Server (NTRS)

    Brasunas, J.; Herman, J.; Kunde, V.; Maguire, W.; Herath, L.; Shaffer, W.; Abbas, M.; Massie, S.

    1988-01-01

    A liquid-nitrogen cooled Fourier transform spectrometer (SIRIS) measures thermal limb-emission of the stratosphere from a balloon platform at a nominal altitude of 40 km, under night and day conditions, with a 3 km vertical resolution. N2O5 and HNO3 mixing ratios inferred from emission spectra are compared with previous measurements and with the predictions from a one-dimensional photochemical model.

  15. DMPP-added nitrogen fertilizer affects soil N2O emission and microbial activity in Southern Italy

    NASA Astrophysics Data System (ADS)

    Vitale, Luca; De Marco, Anna; Maglione, Giuseppe; Polimeno, Franca; Di Tommasi, Paul; Magliulo, Vincenzo

    2014-05-01

    Arable sites contributes to global N2O emission due to massive utilization of nitrogen fertilizers. N2O derives from the biological processes such as nitrification and denitrification influenced by soil nitrogen availability. The use of nitrogen fertilizers added with nitrification inhibitors represents one among the proposed strategy to reduce soil N2O emission form arable sites. The aim of this work was to evaluate the effects of 3,4-dimethylphyrazole phosphate (DMPP), a nitrification inhibitor, on N2O emission and microbial activity of a soil cropped to potato in Southern Italy. The experiment was a randomized block design with two treatments applied and three replicates: control (C) and DMPP (Entec®, K+S Nitrogen) plots, both supplied with the same amount of ammonium nitrate. The nitrogen fertilizer was supplied in three events: at 0 Day After Sowing (DAS; 100 kg N ha-1), at 57 DAS (30 kg N ha-1), and at 71 DAS (30 kg N ha-1). Soil N2O emission was monitored by both dynamic and static chambers. Static chambers were located both on hills and furrows whereas dynamic chambers were located on furrows. Air samples were collected from chambers at different times and analysed by a gas chromatograph (SRI 8610C, Gas Chromatograph). Fluxes were estimated as a linear interpolation of N2O changes over a 30 min time. Microbial biomass and basal respiration were determined as CO2 evolution, analysed by means of an IRGA (Li6200, Licor), on 2 g of fresh soil over a 4h incubation time. Microbial biomass was determined by Substrate Induced Respiration method. Data show no statistical differences in N2O fluxes measured with either dynamic chambers between C and DMPP plots in studied period. However, after the first fertilization event, when the fertilizer was applied as 100 kg N ha-1, the average N2O fluxes measured with static chambers were higher in DMPP plots compared to C plots. In the same period, the microbial biomass significantly decreased in DMPP plots as compared to C

  16. N 2O emission from the semi-arid ecosystem under mineral fertilizer (urea and superphosphate) and increased precipitation in northern China

    NASA Astrophysics Data System (ADS)

    Zhang, Jinfeng; Han, Xingguo

    Soil management and climate change affect N 2O emission significantly. The semi-arid grassland in northern China is under strong anthropogenic disturbance (fertilization and land use) and toward a 30% increase in precipitation in future. To investigate their impacts on N 2O emission, N 2O fluxes were measured monthly in the grassland and abandoned cropland under mineral fertilizer (urea and superphosphate) and increased precipitation during the growing season. During the measured period, WFPS (water filled pore space) from all the treatments never exceeded 70%, suggesting that nitrification was the predominant source of N 2O for all the treatments. Increased precipitation induced an additional growing season emission of 0.28-0.30 kg N 2O-N ha -1 y -1. N 2O emission increased linearly with nitrogen application rate and emission factors (EFs) for grassland and abandoned cropland averaged 0.35% and 0.52%, respectively. Superphosphate addition induced N 2O emission from abandoned cropland ( P<0.05), but had no significant effect in the grassland ( P>0.05). Despite of substantial differences in soil properties, N 2O emissions were not significantly different between the grassland and abandoned cropland ( P>0.05). Increased precipitation and nitrogen application at 15 g N m -2 y -1 across the grassland and abandoned cropland of northern China will increase the growing season emissions of 71.4-76.5 and 139.23 Gg N 2O-N into atmosphere annually. These increased emissions are about 40% and 75% of the annual emission of 186.15 Gg N 2O-N from untreated soils, respectively. Therefore, in the temperate semi-arid ecosystem, abandoned cropland does not constitute a potent source for increasing N 2O while the effect of nitrogen fertilization and increased precipitation cannot be neglected from the regional or national emission.

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

    NASA Astrophysics Data System (ADS)

    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

  18. Linking N2O emission from biochar-amended composting process to the abundance of denitrify (nirK and nosZ) bacteria community.

    PubMed

    Li, Shuqing; Song, Lina; Jin, Yaguo; Liu, Shuwei; Shen, Qirong; Zou, Jianwen

    2016-12-01

    Manure composting has been recognized as an important anthropogenic source of nitrous oxide (N2O) contributing to global warming. However, biochar effect on N2O emissions from manure composting is rarely evaluated, especially by linking it to abundance of denitrifying bacteria community. Results of this study indicated that biochar amendment significantly reduced N2O emissions from manure composting, primarily due to suppression of the nirK gene abundance of denitrifying bacteria. Pearson's correlation analysis showed a significant positive correlation between nirK abundance and N2O fluxes, while a negative correlation between nosZ density and N2O fluxes. Simultaneously, a linear correlation between nirK gene abundance minus nosZ gene abundance with N2O fluxes was also observed. In addition, a statistical model for estimating N2O emissions based on the bacterial denitrifying functional genes was developed and verified to adequately fit the observed emissions. Our results highlighted that biochar amendment would be an alternative strategy for mitigating N2O emissions during manure composting, and the information of related functional bacterial communities could be helpful for understanding the mechanism of N2O emissions. PMID:27207069

  19. Effect of aeration rate on the emission of N2O in anoxic-aerobic sequencing batch reactors (A/O SBRs).

    PubMed

    Hu, Zhen; Zhang, Jian; Li, Shanping; Xie, Huijun; Wang, Jinhe; Zhang, Tingting; Li, Yiran; Zhang, Huayong

    2010-05-01

    Nitrous oxide (N(2)O) is a significant greenhouse gas, and biological nitrogen removal systems have been shown to be a significant N(2)O source. To evaluate the control parameters for N(2)O emission in the wastewater treatment process, N(2)O emissions were compared in the activated sludge from anoxic-aerobic sequencing batch reactors (A/O SBRs) acclimated under different aeration rates, and fed with synthetic wastewater. Results showed that a higher aeration rate led to a smaller N(2)O emission, while reactors acclimated under mild aeration performed the best in terms of nitrogen removal efficiency. Most of the N(2)O was produced during the aerobic phase, regardless of the aeration rate. Trace studies showed that incomplete denitrification appeared to be the major process responsible for high N(2)O emission at a low aeration rate (Run 1), while incomplete nitrification was the reason for N(2)O emission at a higher aeration rate (Run 2 and Run 3). For enhancing the efficiency of nitrogen removal while lowering energy consumption and reducing N(2)O emission, the optimal aeration rate would be 2.7 L(air)/(L(reactor) . h), in terms of the synthetic wastewater used. PMID:20347772

  20. Greenhouse Gas (CH4, CO2 and N2O) Emission Levels by Wastewater Treatment Plant (WWTP) Ponds in Brazil

    NASA Astrophysics Data System (ADS)

    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.

  1. Nitrogen loss from high N-input vegetable fields - a) direct N2O emissions b) Spatiotemporal variability of N species (N2O, NH4+, NO3-) in soils

    NASA Astrophysics Data System (ADS)

    Pfab, H.; Ruser, R.; Palmer, I.; Fiedler, S.

    2009-04-01

    Nitrous oxide is a climate relevant trace gas. It contributes 7.9 % to the total anthropogenic greenhouse gas emission and it is also involved in stratospheric ozone depletion. Approximately 85 % of the anthropogenic N2O emissions result from agricultural activities, more than 50 % are produced during microbial N-turnover processes in soils. Especially soils with high N-input (N-fertilizer and high amount of N in plant residues) like vegetable cropped soils are assumed to cause high N2O losses. The aims of the study presented were (i) to quantify the N2O loss from a vegetable field (lettuce-cauliflower crop rotation), (ii) to calculate an emission factor for the study site in Southwest Germany and to compare this factor with the default value provided by the IPCC (2006) and (iii) to test the emission reduction potential (Ammonium Sulfate Nitrate fertilizer, ASN either by reduced N-fertilization) in comparison with common N doses used for good agricultural practice or by the use of a nitrification inhibitor (DMPP), a banded N-application (lettuce) or a depot fertilization measure (pseudo-CULTAN in order to suppress nitrification). N2O fluxes determined with the closed chamber method were highly variable in time with strongly increased flux rates after N-fertilization in combination with rainfall or irrigation measures and after the incorporation of cauliflower crop residues. Using the mean soil nitrate contents of the top soil of our investigated treatments (0-25 cm depth), we could explain approximately 60 % of the variability of the cumulative N2O losses during the vegetation period of lettuce and cauliflower. The cumulative N2O emissions ranged between 0,99 kg N2O-N ha-1 from the unfertilized control plots (vegetation period) and 6,81 kg N2O-N ha-1 from the plots with the highest N-dose. Based on the guidelines of the IPCC (2006), we calculated an emission factor around 0,9 % for the cropping season. This value is in good agreement with the default value of the

  2. Soil Emissions of N2O and NO in Agricultural Production Systems in the Upper Midwest U.S.: Management Controls and Measurement Issues

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cropped fields in the upper Midwest have the potential to emit relatively large quantities of N2O and NO resulting from soil transformation of N fertilizers applied to crops such as corn and potatoes. The mitigation of N2O emissions may be an effective strategy for offsetting greenhouse gas emission...

  3. Estimating agricultural N2O emissions in France: comparison of a spatialized agro-ecosytem model (CERES-EGC) and a terrestrial biosphere model (O-CN)

    NASA Astrophysics Data System (ADS)

    Massad, R. S.; Prieur, V.; Boukari, E.; Lehuger, S.; Chaumartin, F.; Schultz, M.; Gabrielle, B.

    2012-04-01

    Nitrous oxide (N2O) is a major greenhouse gas and air pollutant. Considered over a 100 year period, it has 298 times more impact 'per unit weight' (Global warming potential) than carbon dioxide. The parties to the United Nations Framework Convention on Climate Change (UNFCCC), including France, are committed to estimate their national nitrous oxide (N2O) budgets and to establish regional programmes of N2O emissions reductions. Agricultural activities are gradually coming into focus as a major GHG emission sector; precise regional estimates of current N2O emissions from arable land are being needed, along with possible means for mitigating emissions. The use of biogeochemical simulation models to estimate N2O fluxes from agricultural soils has obvious benefits. These models provide a unique potential to mechanistically predict N2O emissions from arable soils on both the plot-scale and the regional/national scale on daily time resolutions. In this study we apply two biogeochemical simulation models: CERES-EGC and O-CN all over France for the year 2007 in the perspective of producing an inventory of N2O emissions from croplands. Simulated total N2O emissions from agricultural soils sum up to 20.4 Gg N-N2O/yr with the CERES-EGC model and to 95.1 Gg N-N2O/yr with the O-CN model. Even though the total emissions are largely different between the two models, the temporal and spatial distributions are comparable. When compared to the EDGAR 4.2 emission database we note that O-CN overestimates the annual emissions by approximately a factor of two, whereas CERES-EGC underestimates those emissions. These differences can be explained to a certain extent by the difference in land-use types considered in each of the models and the inventories.

  4. Effects of nitrogen fertilization on soil N2O emissions and soil respiration in temperate grassland in Inner Mongolia, China

    NASA Astrophysics Data System (ADS)

    Dong, Y.; Qi, Y.; Peng, Q.

    2012-04-01

    Nitrogen addition to soil can play a vital role in influencing nitrogen balance and the losses of soil carbon by respiration in N-deficient terrestrial ecosystems. The aim of this study was to clarify the effects of different levels of nitrogen fertilization (HN:200 kg N ha-1y-1, MN:100 kg N ha-1y-1 and LN:50 kg N ha-1y-1) on soil N2O emissions and soil respiration compared with non-fertilization(CK, 0 kg N ha-1y-1), from July 2007 to September 2008, in temperate grassland in Inner Mongolia, China. Several N fertilizer forms were included(CAN:calcium ammonium nitrate, AS:ammonium sulphate and NS:sodium nitrate) and a static closed chamber method was used as gas fluxes measurement. Our data showed that peak N2O fluxes induced by N treatments were concentrated in short periods (2 to 3 weeks) after fertilization in summer and in soil thawing periods in early spring; there were similarly low N2O fluxes from all treatments in the remaining seasons of the year. The three N levels increased annual N2O emissions significantly(P<0.05) in the order of MN>HN>LN compared with the CK(control) treatment in year 1; in year 2, the elevation of annual N2O emissions was significant (P<0.05) by HN and MN treatments but was insignificant by LN treatments (P>0.05). The three N forms also had strong effects on N2O emissions. Significantly (P<0.05) higher annual N2O emissions were observed in the soils of CAN and AS fertilizer treatments than in the soils of NS fertilizer treatments in both measured years, but the difference between CAN and AS was not significant (P>0.05). Annual N2O emission factors (EF) ranged from 0.060 to 0.298% for different N fertilizer treatments in the two observed years, with an overall EF value of 0.125%. The EF values were by far less than the mean default EF proposed by the Intergovernmental Panel on Climate Change(IPCC). Our results also showed that N fertilization did not change the seasonal patterns of soil respiration, which were mainly controlled by soil

  5. [Nutrients conservation of N & P and greenhouse gas reduction of N2O emission during swine manure composting].

    PubMed

    Zheng, Jia-Xi; Wei, Yuan-Song; Wu, Xiao-Feng; Zeng, Xiao-Lan; Han, Sheng-Hui; Fang, Yun

    2011-07-01

    Nitrogen loss and greenhouse gas (N2O) emission occur during animal manure composting, as well as phosphorus loss caused by runoff during land application of animal manure compost. Therefore, the purposes of this study were to simultaneously conserve nutrients of nitrogen & phosphorus and reduce N2O emission during animal manure composting using modified salts which are made from industrial solid waste. Experiments of in-vessel swine manure composting at lab-scale were carried out to investigate and compare effects of modified red-mud (MR) and modified forsterite (MF) as additives on nutrients conservation and greenhouse gas (N2O) reduction. As far as the nitrogen loss calculated on the basis of ammonia and nitrous oxide is concerned, the least nitrogen loss at only 6.38% of TKN occurred in the swine manure composting with MF addition at pH 7.0 +/- 0.2, compared with those of MR addition at pH 5.0 +/- 0.2 at 11.07% of TKN and the control at 14.68% of TKN, respectively. The best results of ammonia and nitrous oxide mitigation during swine manure composting were the treatments with MR addition and MF addition, which nitrogen losses were at 2.13% of TKN as NH3 and 0.65% of TKN, respectively. These results clearly showed that the modified salt additives from red-mud and forsterite were useful for saving nitrogen and reducing N2O emission. Moreover, the contents of soluble orthophosphate in swine manure compost with the addition of both modified salts were less than that of the control, which is helpful to reduce P loss during land application of swine manure compost. PMID:21922829

  6. Emissions of N2O from tropical forest soils - Response to fertilization with NH4(+), NO3(-), and PO4(3-)

    NASA Technical Reports Server (NTRS)

    Keller, M.; Kaplan, W. A.; Wofsy, S. C.; Da Costa, Jose Maria

    1988-01-01

    Undisturbed oxisols in a central Amazon tropical forest were fertilized with ammonium, nitrate, or phosphate. Enhanced emissions of N2O were observed for all treatments within one day of fertilization, with the response NO3(-) much greater than NH4(+) much greater than PO4(3-). Approximately, 0.5 percent of applied NO3(-) was converted to N2O within two weeks after application, with less than 0.1 percent of the NH4(+) converted to N2O. These experiments reveal a potentially large source of N2O from microbial reduction of NO3(-) in the clay soils of Amazonia.

  7. The influence of N-fertilization regimes on N2O emissions and denitrification in rain-fed cropland during the rainy season.

    PubMed

    Dong, Zhixin; Zhu, Bo; Zeng, Zebin

    2014-11-01

    The effects of nitrogen fertilization regimes on N2O emissions and denitrification rates were evaluated by in situ field incubation experiments with intact soil cores and the acetylene block technique. Intact soil cores were collected from long-term field experiments involving several N fertilization regimes, including single synthetic N fertilizer (N), organic manure (OM), synthetic N, P, K fertilizer (NPK), organic manure with synthetic fertilizer (OMNPK), crop straw residue with synthetic fertilizer (SRNPK) and no nitrogen fertilizer (NF). N2O was sampled from the head space of the cylinders to determine the daily N2O emission and denitrification rate. The results showed that the N2O emissions were greatly influenced by the specific fertilization regime even when the same nitrogen rate was applied. The mean N2O emissions and denitrification rates from the N, OM, NPK, OMNPK and SRNPK treatment were 2.22, 2.66, 1.94, 2.53, 1.67 and 4.63, 5.96, 4.15, 5.41, 3.65 mg per m(2) per day, respectively. The application of OM significantly increased the N2O emission and denitrification compared to the application of NPK because of the high soil organic carbon (SOC) content of OM. However, SRNPK increased the SOC content and decreased the N2O emissions significantly compared to the OM and OMNPK treatments because the addition of crop straw with a high C/N ratio to soil with a low inorganic N content induced N immobilization. The contents of soil nitrate and ammonium were the main limiting factors for N2O emissions in a positive regression as follows: Ln (N2O) = 2.511 + 1.258 × Ln ([NH4(+)] + [NO3(-)]). Crop straw residue combined with synthetic fertilizer is recommended as an optimal strategy for mitigating N2O emissions and denitrification-induced N loss in rain-fed croplands. PMID:25220444

  8. Linking N2O emissions from biochar-amended soil to the structure and function of the N-cycling microbial community

    NASA Astrophysics Data System (ADS)

    Harter, Johannes; Krause, Hans-Martin; Schuettler, Stefanie; Ruser, Reiner; Fromme, Markus; Scholten, Thomas; Kappler, Andreas; Behrens, Sebastian

    2014-05-01

    Nitrous oxide (N2O) contributes 8% to global greenhouse gas emissions. Agricultural sources represent about 60% of anthropogenic N2O emissions. Most agricultural N2O emissions are due to increased fertilizer application. A considerable fraction of nitrogen fertilizers are converted to N2O by microbially-mediated processes. Soil amended with biochar has been demonstrated to reduce N2O emissions in the field and in laboratory experiments. Although N2O emission mitigation following soil biochar amendment has been reported frequently the underlying processes and specific role of the nitrogen cycling microbial community in decreasing soil N2O emissions has not been subject of systematic investigation. To investigate the impact of biochar on the microbial community of nitrogen-transforming microorganisms we performed a microcosm study with arable soil amended with different amounts (0%, 2% and 10% (w/w)) of high-temperature wood derived biochar. By quantifying the abundance and activity of functional marker genes of microbial nitrogen fixation (nifH), nitrification (amoA) and denitrification (nirK, nirS and nosZ) using quantitative real-time PCR we found that biochar addition enhanced microbial nitrous oxide reduction and increased the abundance of microorganisms capable of N2-fixation. Soil biochar amendment increased the relative gene and transcript copy numbers of the nosZ-encoded bacterial N2O reductase, suggesting a mechanistic link to the observed reduction in N2O emissions. Our findings contribute to a better understanding of the impact of biochar on the nitrogen cycling microbial community and the consequences of soil biochar amendment for microbial nitrogen transformation processes and N2O emissions from soil.

  9. Floc-based sequential partial nitritation and anammox at full scale with contrasting N2O emissions.

    PubMed

    Desloover, Joachim; De Clippeleir, Haydée; Boeckx, Pascal; Du Laing, Gijs; Colsen, Joop; Verstraete, Willy; Vlaeminck, Siegfried E

    2011-04-01

    New Activated Sludge (NAS(®)) is a hybrid, floc-based nitrogen removal process without carbon addition, based on the control of sludge retention times (SRT) and dissolved oxygen (DO) levels. The aim of this study was to examine the performance of a retrofitted four-stage NAS(®) plant, including on-line measurements of greenhouse gas emissions (N(2)O and CH(4)). The plant treated anaerobically digested industrial wastewater, containing 264 mg N L(-1), 1154 mg chemical oxygen demand (COD) L(-1) and an inorganic carbon alkalinity of 34 meq L(-1). The batch-fed partial nitritation step received an overall nitrogen loading rate of 0.18-0.22 kg N m(-3) d(-1), thereby oxidized nitrogen to nitrite (45-47%) and some nitrate (13-15%), but also to N(2)O (5.1-6.6%). This was achieved at a SRT of 1.7 d and DO around 1.0 mg O(2) L(-1). Subsequently, anammox, denitrification and nitrification compartments were followed by a final settler, at an overall SRT of 46 d. None of the latter three reactors emitted N(2)O. In the anammox step, 0.26 kg N m(-3) d(-1) was removed, with an estimated contribution of 71% by the genus Kuenenia, which constituted 3.1% of the biomass. Overall, a nitrogen removal efficiency of 95% was obtained, yielding a dischargeable effluent. Retrofitting floc-based nitrification/denitrification with carbon addition to NAS(®) allowed to save 40% of the operational wastewater treatment costs. Yet, a decrease of the N(2)O emissions by about 50% is necessary in order to obtain a CO(2) neutral footprint. The impact of emitted CH(4) was 20 times lower. PMID:21440280

  10. Effects of Soil Temperature, Flooding, and Organic Matter Addition on N2O Emissions from a Soil of Hongze Lake Wetland, China

    PubMed Central

    Lu, Yan; Xu, Hongwen

    2014-01-01

    The objectives of this study were to test the effects of soil temperature, flooding, and raw organic matter input on N2O emissions in a soil sampled at Hongze Lake wetland, Jiangsu Province, China. The treatments studied were—peat soil (I), peat soil under flooding (II), peat soil plus raw organic matter (III), and peat soil under flooding plus organic matter. These four treatments were incubated at 20°C and 35°C. The result showed that temperature increase could enhance N2O emissions rate and cumulative emissions significantly; moreover, the flooded soil with external organic matter inputs showed the lowest cumulative rise in N2O emissions due to temperature increment. Flooding might inhibit soil N2O emissions, and the inhibition was more pronounced after organic matter addition to the original soil. Conversely, organic matter input explained lower cumulative N2O emissions under flooding. Our results suggest that complex interactions between flooding and other environmental factors might appear in soil N2O emissions. Further studies are needed to understand potential synergies or antagonisms between environmental factors that control N2O emissions in wetland soils. PMID:25133216

  11. N2:O emissions from a cultivated Andisol after application of nitrogen fertilizers with or without nitrification inhibitor under soil moisture regime.

    PubMed

    Fan, Xiao-Hui; Haruo, Tsuruta

    2004-01-01

    The aim of this work was to examine the emission of N2O from soils following addition of nitrogen fertilizer with a nitrification inhibitor (+inh) or without the nitrification inhibitor(-inh) at different soil water regime. Higher soil moisture contents increased the total N2O emissions in all treatments with total emissions being 7 times larger for the CK and > 20 times larger for the fertilizer treatments at 85% WFPS (soil water filled pore space) than at 40% WFPS. The rates of N2O emissions at 40% WFPS under all treatments were small. The maximum emission rate at 55% WFPS without the nitrification inhibitor (-inh) occurred later (day 11) than those of 70% WFPS (-inh) samples (day 8). The inhibition period was 4-22 d for 55% WFPS and 1-15 d for 70% WFPS comparing the rates of N2O emissions treated (+inh) with (-inh). The maximum emission rates at 85% WFPS were higher than those at the other levels of soil water content for all treatments. The samples (+inh) released less N2O than (-inh) samples at the early stage. Nevertheless, N2O emissions from (+inh) samples lasted longer than in the (-inh) treatment. Changes in mineral N at 55%, 70% and 85% WFPS followed the same pattern. NH4(+) -N concentrations decreased while NO3(-) -N concentrations increased from the beginning of incubation. NH4(+) -N concentrations from 40% WFPS treatment declined more slowly than those of the other three levels of soil water content. Nitrification was faster in the (-inh) samples with 100% NH4(+) -N nitrified after 22 d (50% WFPS) and 15 d (70% and 85% WFPS). N2O emissions increased with soil water content. Adding N-fertilizer increased emissions of N2O. The application of the nitrification inhibitor significantly reduced total N2O emissions from 30.5% (at 85% WFPS) to 43.6% (at 55% WFPS). PMID:15559801

  12. Nitrogen availability and soil N2O emissions following conversion of forests to coffee in southern Sumatra

    NASA Astrophysics Data System (ADS)

    Verchot, Louis V.; Hutabarat, Lusida; Hairiah, Kurniatun; van Noordwijk, Meine

    2006-12-01

    Changes in land use impact on the N cycle with both local and global consequences. We examined how conversion of forest to agriculture in one catchment in southern Sumatra altered N availability and soil N2O emission. Measurements were made along a chronosequence of forest land converted to coffee gardens. A number of different management practices were also examined. Inorganic N stocks and N cycling rates were highest in the forest and lower in the coffee gardens. The forest and young conversion sites appeared to be N limited, whereas the older agricultural sites and the more intensively managed sites were not as strongly N limited. N2O emissions were low in the forest (<2 kgN ha-1yr-1) and increased sharply following deforestation. Emissions on recently cleared land were 4.6 kgN ha-1yr-1 and 8.4 kgN ha-1yr-1 in a 1-year-old coffee garden. Emissions in the older coffee gardens were lower with the lowest flux observed in a 10 year old site (1.8 kgN ha-1yr-1). We explored the effects of different types of management approaches that farmers are using in this landscape. Emissions in an 18-year-old multistrata coffee garden with a significant overstory of N fixing trees were 5 times greater (15.5 kg ha-1yr-1) than emissions from forests. We also found that intensive organic matter management produced high emissions. To understand the spatial and temporal variability of the N2O emissions we used the hole-in-the-pipe conceptual model. N2O fluxes were lowest on N limited sites. Soil water content also played an important role and emissions were highest when water filled pore space (WFPS) was between 85 and 95%. A number of formulations of this model have been applied in different ways over the years to explain spatial and temporal variation in the soil N-oxide flux, and in this study we found the mechanistic explanation useful. Our study suggests that land use change and intensification of agriculture in N limited highland landscapes may significantly increase the

  13. Biogenic emissions of CO2 and N2O at multiple depths increase exponentially during a simulated soil thaw for a northern prairie Mollisol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil respiration occurs at depths below the surface, but belowground data are lacking to support multilayer models of soil CO2 and N2O emissions. In particular, Q10s for CO2 and N2O within soil profiles are needed to determine if temperature sensitivities calculated at the surface are similar to th...

  14. CO(2) and N(2)O emissions in a soil chronosequence at a glacier retreat zone in Maritime Antarctica.

    PubMed

    Thomazini, A; Mendonça, E S; Teixeira, D B; Almeida, I C C; La Scala, N; Canellas, L P; Spokas, K A; Milori, D M B P; Turbay, C V G; Fernandes, R B A; Schaefer, C E G R

    2015-07-15

    Studies of C cycle alterations are extremely important to identify changes due to climate change, especially in the polar ecosystem. The objectives of this study were to (i) examine patterns of soil CO2-C and N2O-N emissions, and (ii) evaluate the quantity and quality of soil organic matter across a glacier retreat chronosequence in the Maritime Antarctica. Field measurements were carried out during January and February 2010 (summer season) along a retreating zone of the White Eagle Glacier, at King George Island, Maritime Antarctica. Soil samples (0-10cm) were collected along a 500-m transect at regular intervals to determine changes in soil organic matter. Field CO2-C emission measurements and soil temperature were carried out at regular intervals. In addition, greenhouse gas production potentials were assessed through 100days laboratory incubations. Soils exposed for a longer time tended to have greater concentrations of soluble salts and possess sandier textures. Total organic C (3.59gkg(-1)), total N (2.31gkg(-1)) and labile C (1.83gkg(-1)) tended to be lower near the glacier front compared with sites away from it, which is correlated with decreasing degree of humification of the soil organic matter with exposure time. Soil CO2-C emissions tended to increase with distance from the glacier front. On average, the presence of vegetation increased CO2-C emissions by 440%, or the equivalent of 0.633g of CO2-C m(-2)h(-1). Results suggest that newly exposed landsurfaces undergo soil formation with increasing labile C input from vegetation, accompanied by increasing soil CO2-C emissions. Despite the importance of exposure time on CO2-C production and emissions, there was no similar trend in soil N2O-N production potentials as a function of glacial retreat. For N2O, instead, the maximum production occurred in sites with the first stages of vegetation growth. PMID:25855094

  15. Quantitative importance of denitrification and N2O emission in an N-saturated subtropical forest catchment, southwest China

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Dörsch, P.; Mulder, J.

    2009-04-01

    Anthropogenic emission of nitrogen in the environment has increased rapidly, due to fast economic growth. This has resulted in increased deposition rates of reactive nitrogen, primarily as NOx (from fossil fuel combustion) and NH3 (from fertilizer production and animal husbandry). In response, temperate and boreal forests may develop nitrogen saturation, characterized by increased leaching of nitrate. In addition, elevated emission of N2 and N2O, due to nitrification and denitrification, may occur. To date, few studies exist quantifying the nitrogen balance, including N2 and N2O production, in nitrogen-saturated, monsoonal, sub-tropical forest ecosystems in south-west China. Since nitrate contributes to the eutrophication of stream water, and N2O is a potent greenhouse gas, it is important to quantitatively understand the role of nitrification and denitrification in the nitrogen cycle. Several subtropical forests in southwest China, receiving elevated nitrogen deposition (30-73 kg N ha-1 a-1; Zhang. et al., 2008), are characterized by high temperature and soil moisture content in much of the growing season. This may cause a much stronger intensity of denitrification compared with that in temperate and boreal forests. In turn this may lead to decreased nitrate leaching and a higher potential of N2O emission. In my PhD project, I will investigate the nitrogen cycle in a forest catchment (TieShanPing; TSP), which is near one of the biggest cities, Chongqing, in southwest China. Previous research suggests high nitrogen deposition (3.52 gN m-2 a-1), but low nitrogen flux (0.57 gN m-2 a-1) in runoff (Chen & Mulder, 2007). Tree growth, and thus plant N uptake, is limited and nitrate fluxes below the root zone are relatively large, suggesting ‘N-saturation'. Based on this, we hypothesize that significant amounts of nitrogen are emitted as gases, with denitrification playing an important role, and N2 and N2O (especially N2) being major components of the emitted gases

  16. Characterization of N2O emission and associated bacterial communities from the gut of wood-feeding termite Nasutitermes voeltzkowi.

    PubMed

    Majeed, Muhammad Zeeshan; Miambi, Edouard; Riaz, Muhammad Asam; Brauman, Alain

    2015-09-01

    Xylophagous termites rely on nitrogen deficient foodstuff with a low C/N ratio. Most research work has focused on nitrogen fixation in termites highlighting important inflow and assimilation of atmospheric nitrogen into their bodies fundamentally geared up by their intestinal microbial symbionts. Most of termite body nitrogen is of atmospheric origin, and microbially aided nitrification is the principal source of this nitrogen acquisition, but contrarily, the information regarding potent denitrification process is very scarce and poorly known, although the termite gut is considered to carry all favorable criteria necessary for microbial denitrification. Therefore, in this study, it is hypothesized that whether nitrification and denitrification processes coexist in intestinal milieu of xylophagous termites or not, and if yes, then is there any link between the denitrification product, i.e., N2O and nitrogen content of the food substrate, and moreover where these bacterial communities are found along the length of termite gut. To answer these questions, we measured in vivo N2O emission by Nasutitermes voeltzkowi (Nasutitermitinae) maintained on different substrates with varying C/N ratio, and also, molecular techniques were applied to study the diversity (DGGE) and density (qPCR) of bacterial communities in anterior and posterior gut portions. Rersults revealed that xylophagous termites emit feeble amount of N2O and molecular studies confirmed this finding by illustrating the presence of an ample density of N2O-reductase (nosZ) gene in the intestinal tract of these termites. Furthermore, intestinal bacterial communities of these termites were found more dense and diverse in posterior than anterior portion of the gut. PMID:25687762

  17. Linking N2O emissions from biochar-amended soil to the structure and function of the N-cycling microbial community

    PubMed Central

    Harter, Johannes; Krause, Hans-Martin; Schuettler, Stefanie; Ruser, Reiner; Fromme, Markus; Scholten, Thomas; Kappler, Andreas; Behrens, Sebastian

    2014-01-01

    Nitrous oxide (N2O) contributes 8% to global greenhouse gas emissions. Agricultural sources represent about 60% of anthropogenic N2O emissions. Most agricultural N2O emissions are due to increased fertilizer application. A considerable fraction of nitrogen fertilizers are converted to N2O by microbiological processes (that is, nitrification and denitrification). Soil amended with biochar (charcoal created by pyrolysis of biomass) has been demonstrated to increase crop yield, improve soil quality and affect greenhouse gas emissions, for example, reduce N2O emissions. Despite several studies on variations in the general microbial community structure due to soil biochar amendment, hitherto the specific role of the nitrogen cycling microbial community in mitigating soil N2O emissions has not been subject of systematic investigation. We performed a microcosm study with a water-saturated soil amended with different amounts (0%, 2% and 10% (w/w)) of high-temperature biochar. By quantifying the abundance and activity of functional marker genes of microbial nitrogen fixation (nifH), nitrification (amoA) and denitrification (nirK, nirS and nosZ) using quantitative PCR we found that biochar addition enhanced microbial nitrous oxide reduction and increased the abundance of microorganisms capable of N2-fixation. Soil biochar amendment increased the relative gene and transcript copy numbers of the nosZ-encoded bacterial N2O reductase, suggesting a mechanistic link to the observed reduction in N2O emissions. Our findings contribute to a better understanding of the impact of biochar on the nitrogen cycling microbial community and the consequences of soil biochar amendment for microbial nitrogen transformation processes and N2O emissions from soil. PMID:24067258

  18. Linking N2O emissions from biochar-amended soil to the structure and function of the N-cycling microbial community.

    PubMed

    Harter, Johannes; Krause, Hans-Martin; Schuettler, Stefanie; Ruser, Reiner; Fromme, Markus; Scholten, Thomas; Kappler, Andreas; Behrens, Sebastian

    2014-03-01

    Nitrous oxide (N2O) contributes 8% to global greenhouse gas emissions. Agricultural sources represent about 60% of anthropogenic N2O emissions. Most agricultural N2O emissions are due to increased fertilizer application. A considerable fraction of nitrogen fertilizers are converted to N2O by microbiological processes (that is, nitrification and denitrification). Soil amended with biochar (charcoal created by pyrolysis of biomass) has been demonstrated to increase crop yield, improve soil quality and affect greenhouse gas emissions, for example, reduce N2O emissions. Despite several studies on variations in the general microbial community structure due to soil biochar amendment, hitherto the specific role of the nitrogen cycling microbial community in mitigating soil N2O emissions has not been subject of systematic investigation. We performed a microcosm study with a water-saturated soil amended with different amounts (0%, 2% and 10% (w/w)) of high-temperature biochar. By quantifying the abundance and activity of functional marker genes of microbial nitrogen fixation (nifH), nitrification (amoA) and denitrification (nirK, nirS and nosZ) using quantitative PCR we found that biochar addition enhanced microbial nitrous oxide reduction and increased the abundance of microorganisms capable of N2-fixation. Soil biochar amendment increased the relative gene and transcript copy numbers of the nosZ-encoded bacterial N2O reductase, suggesting a mechanistic link to the observed reduction in N2O emissions. Our findings contribute to a better understanding of the impact of biochar on the nitrogen cycling microbial community and the consequences of soil biochar amendment for microbial nitrogen transformation processes and N2O emissions from soil. PMID:24067258

  19. 40 CFR Table Aa-1 to Subpart Aa of... - Kraft Pulping Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Kraft Pulping Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O AA Table AA-1 to Subpart AA of Part 98 Protection of Environment... Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O Wood furnish Biomass-based emissions...

  20. 40 CFR Table Aa-1 to Subpart Aa of... - Kraft Pulping Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Kraft Pulping Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O AA Table AA-1 to Subpart AA of Part 98 Protection of Environment... Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O Wood furnish Biomass-based emissions...

  1. 40 CFR Table Aa-1 to Subpart Aa of... - Kraft Pulping Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Kraft Pulping Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O AA Table AA-1 to Subpart AA of Part 98 Protection of Environment... Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O Wood furnish Biomass-based emissions...

  2. Nitrogen loss from high N-input vegetable fields: a) Direct N2O emissions b) Spatiotemporal variability of N species (N2O, NH4+, NO3-) in soils

    NASA Astrophysics Data System (ADS)

    Palmer, I.; Pfab, H.; Ruser, R.; Fiedler, S.

    2009-04-01

    Nitrous oxide (N2O) is a greenhouse gas contributing to stratospheric ozone depletion. Soils are considered to be the major (70%) source for atmospheric N2O. Agriculture in general accounts for about 85% of the anthropogenic N2O emissions. Whereas 80% of these, are emitted from ag-riculturally used soils. Such estimations of N2O fluxes are associated with a high degree of uncertainties. Uncertainty of source strength estimates mainly results from local scale variability of known and unknown sources. It is not known how much uncertainty is due to unmeasured sources. For example, considerations of N2O fluxes from soils used for intensive vegetable production within inventories are still missing. We speculate that these types of arable soils act as ‚hot spots' for N2O. Given conditions (1) high N-input due to fertilization in concert with (2) easily mineralizable harvest residues should pro-mote disproportional high reaction rates in N-cycling and enhance N2O production as a by-product of nitrification and denitrification. Our investigation focused on the influence of: (1) N-input level (Ammonium Sulfate Nitrate (ASN)) below and above common N doses used for "good agricultural practice". (2) Application of modified fertilizers including nitrification inhibitor DMPP (Dimethylpyrazolphosphate, ENTEC®) and depot fertilization (pseudo-CULTAN) in comparison to non-fertilized control and common ASN application. (3) Effects of plant residues on N-cycling and (4) the deduction of mitigation strategies to reduce the potential N-loss from theses sites. The study was carried out during summer and autumn 2008 on a field cropped with cauliflower, located at the "Heidfeldhof" (South-West Germany; MAT 10.5°C, MAP 660 mm). Three different N-species (N2O; within gaseous soil phase, ammonium (NH4+) and nitrate (NO3-) extracted from bulk soil) were measured weekly in three different soil depths (0-25 cm; 25-50 cm and 50-75 cm) in a fully randomized field design. At same depths water

  3. N2O, NO, N2, and CO2 emissions from tropical savanna and grassland of Northern Australia: an incubation experiment with intact soil cores

    NASA Astrophysics Data System (ADS)

    Werner, C.; Reiser, K.; Dannenmann, M.; Hutley, L. B.; Jacobeit, J.; Butterbach-Bahl, K.

    2014-06-01

    Strong seasonal variability of hygric and thermal soil conditions are a defining environmental feature in Northern Australia. However, how such changes affect the soil-atmosphere exchange of nitrous oxide (N2O), nitric oxide (NO) and dinitrogen (N2) is still not well explored. By incubating intact soil cores from four sites (3 savanna, 1 pasture) under controlled soil temperatures (ST) and soil moisture (SM) we investigated the release of the trace gas fluxes of N2O, NO and carbon dioxide (CO2). Furthermore, the release of N2 due to denitrification was measured using the helium gas flow soil core technique. Under dry pre-incubation conditions NO and N2O emission were very low (<7.0 ± 5.0 μg NO-N m-2 h-1; <0.0 ± 1.4 μg N2O-N m-2 h-1) or in case of N2O, even a net soil uptake was observed. Substantial NO (max: 306.5 μg N m-2 h-1) and relatively small N2O pulse emissions (max: 5.8 ± 5.0 μg N m-2 h-1) were recorded following soil wetting, but these pulses were short-lived, lasting only up to 3 days. The total atmospheric loss of nitrogen was dominated by N2 emissions (82.4-99.3% of total N lost), although NO emissions contributed almost 43.2% at 50% SM and 30 °C ST. N2O emissions were systematically higher for 3 of 12 sample locations, which indicates substantial spatial variability at site level, but on average soils acted as weak N2O sources or even sinks. Emissions were controlled by SM and ST for N2O and CO2, ST and pH for NO, and SM and pH for N2.

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

    PubMed

    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. PMID:26811747

  5. Ecological Controls on N2O Emission in Surface Litter and Near-surface Soil of a Managed Grassland: Modelling and Measurements

    NASA Astrophysics Data System (ADS)

    Grant, Robert; Neftel, Albrecht; Calanca, Pierluigi

    2016-04-01

    Large variability in N2O emissions from managed grasslands may occur because most emissions originate in surface litter or near-surface soil where variability in soil water content (q) and temperature (Ts) is greatest. To determine whether temporal variability in q and Ts of surface litter and near-surface soil could explain that in N2O emissions, a simulation experiment was conducted with ecosys, a comprehensive mathematical model of terrestrial ecosystems in which processes governing N2O emissions were represented at high temporal and spatial resolution. Model performance was verified by comparing N2O emissions, CO2 and energy exchange, and q and Ts modelled by ecosys with those measured by automated chambers, eddy covariance (EC) and soil sensors at an hourly time-scale during several emission events from 2004 to 2009 in an intensively managed pasture at Oensingen, Switzerland. Both modelled and measured events were induced by precipitation following harvesting and subsequent fertilizing or manuring. These events were brief (2 - 5 days) with maximum N2O effluxes that varied from < 1 mg N m-2 h-1 in early spring and autumn to > 3 mg N m-2 h-1 in summer. Only very small emissions were modelled or measured outside these events. In the model, emissions were generated almost entirely in surface litter or near-surface (0 - 2 cm) soil, at rates driven by N availability with fertilization vs. N uptake with grassland regrowth, and by O2 limitation from wetting relative to O2 demand from respiration. In the model, NOx availability relative to O2 limitation governed both the reduction of more oxidized electron acceptors to N2O and the reduction of N2O to N2, so that the magnitude of N2O emissions was not simply related to surface and near-surface q and Ts. Modelled N2O emissions were found to be sensitive to defoliation intensity and timing (relative to that of fertilization) which controlled plant N uptake and soil q and Ts prior to and during emission events. In a model

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

    PubMed

    Case, Sean D C; Gómez-Muñoz, Beatriz; Magid, Jakob; Jensen, Lars Stoumann

    2016-07-01

    Previous studies found that thermally dried biosolids contained more mineralisable organic nitrogen (N) than the raw or anaerobically digested (AD) biosolids they were derived from. However, the effect of thermal drying temperature on biosolid N availability is not well understood. This will be of importance for the value of the biosolids when used to fertilise crops. We sourced AD biosolids from a Danish waste water treatment plant (WWTP) and dried it in the laboratory at 70, 130, 190 or 250 °C to >95 % dry matter content. Also, we sourced biosolids from the WWTP dried using its in-house thermal drying process (input temperature 95 °C, thermal fluid circuit temperature 200 °C, 95 % dry matter content). The drying process reduced the ammonium content of the biosolids and reduced it further at higher drying temperatures. These findings were attributed to ammonia volatilisation. The percentage of mineralisable organic N fraction (min-N) in the biosolids, and nitrous oxide (N2O) and carbon dioxide (CO2) production were analysed 120 days after addition to soil. When incubated at soil field capacity (pF 2), none of the dried biosolids had a greater min-N than the AD biosolids (46.4 %). Min-N was lowest in biosolids dried at higher temperatures (e.g. 19.3 % at 250 °C vs 35.4 % at 70 °C). Considering only the dried biosolids, min-N was greater in WWTP-dried biosolids (50.5 %) than all of the laboratory-dried biosolids with the exception of the 70 °C-dried biosolids. Biosolid carbon mineralisation (CO2 release) and N2O production was also the lowest in treatments of the highest drying temperature, suggesting that this material was more recalcitrant. Overall, thermal drying temperature had a significant influence on N availability from the AD biosolids, but drying did not improve the N availability of these biosolids in any case. PMID:27068895

  7. Organically treated biochar increases plant production and reduces N2O emissions: mechanistic insights by 15N tracing

    NASA Astrophysics Data System (ADS)

    Kammann, Claudia; Messerschmidt, Nicole; Clough, Tim; Schmidt, Hans-Peter; Marhan, Sven; Koyro, Hans-Werner; Steffens, Diedrich; Müller, Christoph

    2014-05-01

    Pyrogenic carbon (biochar) offers considerable potential for carbon capture and soil storage (CCSS) compared to other, less recalcitrant soil-C additives. Recent meta-analysis demonstrated that it can significantly reduce agricultural N2O emissions. Freshly produced biochars, however, do not always have yield-improving effects, i.e. there is no immediate economic incentive for using it. Hence, combining biochar with organic nutrient-rich amendments may be a promising agricultural strategy to accelerate CCSS, but it is unclear if biochar still reduces N2O emissions, in particular when it may act as nutrient carrier. We explored the potential of biochar to improve the GHG-cost/yield ratio and thereby its socio-economic value as soil amendment in two subsequent studies under controlled conditions: (1) A proof-of-concept study where the effects of untreated biochar were compared to those of co-composted biochar combined with stepwise improved nutritional regimes (+/- compost; +/- mineral-N application), and (2) a 15N-labeling-tracing study to unravel N exchange on biochar particles and N2O production and reduction mechanisms. Both studies were carried out in nutrient-poor sandy soils, the most likely initial target soils for biochar-CCSS strategies. While the untreated biochar reduced plant growth under N-limiting conditions, or at best did not reduce it, the co-composted biochar always significantly stimulated plant growth. The relative stimulation was largest with the lowest nutrient additions (305% versus 61% of control with untreated biochar). Electro-ultra-filtration analyses revealed that the co-composted but not the untreated biochar carried considerable amounts of easily extractable as well as more strongly sorbed plant nutrients, in particular nitrate and phosphorus. The subsequent 15N labelling-tracing study revealed that the co-composted biochar still (i) acted as a mineral-N exchange site for nitrate and ammonium despite its N-preloading, (ii) reduced N2O

  8. The N2O and NO emissions of three types of agricultural system in North China Plain

    NASA Astrophysics Data System (ADS)

    Yan, G.

    2012-04-01

    The two anthropogenic induced N-trace gases, a powerful greenhouse gas N2O and an important atmosphere pollution gas NO, which are getting more and more concerned. It is reported that agricultural soil is the main sources of the two gases, which globally contribute to 1.7-4.8 Tg N yr-1 and 1.6 Tg N yr-1, respectively. North China Plain is a seriously intensive agriculture area of china, with 300,000 km2 which produces approximate one-fourth of China's total grain yield. The winter wheat - summer maize rotation (W-M), winter wheat - scallion rotation (W-S), greenhouse vegetable (GV) are three typical cultivation systems in this region. In the Recent 40 years, the conflicts between the demand of high yield and excess fertilizer application have been getting increasingly outstanding. Under such circumstances, we have conduced one and a half years to two years field measurement to investigate the N2O and NO emissions. The mean accumulated N2O emissions were 4.4, 4.4, 23.5 kg N ha-1 yr-1, emission factors were 0.65%, 0.52%, 0.90% for the W-M, W-S, and GV systems, respectively. The mean accumulated NO emissions were 2.0, 0.7, 3.6 kg N ha-1 yr-1, emission factors were 0.3%, 0.07%, 0.14% for the relative systems, respectively. The emission patterns was typically event driven pattern, except the GV system which mainly caused by basal fertilizer application. Obviously, fertilizer application was the main driven factor. What's more, environment factors (e.g. WFPS, soil texture) also affected the two gases emissions. The denitrification was the domain process during the entire growing period for W-S and GV systems, however, referring to W-M system, both nitrification and denitrification played an important role during the entire period. The nitrification inhibitors application may be an available strategy to mitigate the two N- trace gases emissions.

  9. Taking advantage of data on N leaching to improve estimates of N2O emission reductions from agriculture in response to management changes

    NASA Astrophysics Data System (ADS)

    Gurwick, N. P.; Tonitto, C.

    2012-12-01

    Estimates of reductions in N2O emissions from agricultural soils associated with different crop management practices often focus on in-field emissions. This is particularly true in the context of policy development for carbon offsets which are highly relevant in California, given the state's global warming protection law (AB 32). However, data sets often do not cover an entire year, missing key times such as spring thaw, and only rarely do they span multiple years even though inter-annual variation can be large. In the most productive grain systems on tile-drained Mollisols in the U.S. there are no long-term data sets of N2O flux, although these agroecosystems have the highest application rates of N fertilizer in grain systems and are prime candidates for large reductions in N2O emissions. In contrast, estimates of the influence of management practices like cover crops are much stronger because more data are available, and downstream N2O emissions should shift proportionally. Nevertheless, these changes in downstream emissions are frequently not included in estimates of N2O flux change. As an example, cereal cover crops reduce N leakage by 70%, and leguminous cover crops reduce N leakage by 40%. These data should inform estimates of downstream N2O emissions from agricultural fields, particularly in the context of protocol development, where project developers or aggregators will have information about basic management of individual crop fields. Even the IPCC default guidelines for simple (Tier 1) emission factors could take this information into account. Despite the complexity of estimating downstream N2O emissions in the absence of site-specific hydrology data, the IPCC estimates that 30% of applied N is lost and that between 0.75% and 1.0 % of lost N is converted to N2O. That single estimate should be refined based on data showing that leaching varies with management practices.

  10. 40 CFR Table Aa-2 to Subpart Aa of... - Kraft Lime Kiln and Calciner Emissions Factors for Fossil Fuel-Based CH4 and N2O

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Kraft Lime Kiln and Calciner Emissions Factors for Fossil Fuel-Based CH4 and N2O AA Table AA-2 to Subpart AA of Part 98 Protection of Environment... and Calciner Emissions Factors for Fossil Fuel-Based CH4 and N2O Fuel Fossil fuel-based...

  11. 40 CFR Table Aa-2 to Subpart Aa of... - Kraft Lime Kiln and Calciner Emissions Factors for Fossil Fuel-Based CH4 and N2O

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Kraft Lime Kiln and Calciner Emissions Factors for Fossil Fuel-Based CH4 and N2O AA Table AA-2 to Subpart AA of Part 98 Protection of Environment... and Calciner Emissions Factors for Fossil Fuel-Based CH4 and N2O Fuel Fossil fuel-based...

  12. 40 CFR Table Aa-2 to Subpart Aa of... - Kraft Lime Kiln and Calciner Emissions Factors for Fossil Fuel-Based CH4 and N2O

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Kraft Lime Kiln and Calciner Emissions Factors for Fossil Fuel-Based CH4 and N2O AA Table AA-2 to Subpart AA of Part 98 Protection of Environment... and Calciner Emissions Factors for Fossil Fuel-Based CH4 and N2O Fuel Fossil fuel-based...

  13. Seasonal CH4 and N2O emissions and plant growth characteristics of several cultivars in direct seeded rice systems

    NASA Astrophysics Data System (ADS)

    Simmonds, M.; Anders, M. M.; Adviento-Borbe, M. A.; Van Kessel, C.; McClung, A.; Linquist, B.

    2014-12-01

    Understanding cultivar effects on field greenhouse gas (GHG) emissions in rice (Oryza sativa L.) systems is needed to improve the accuracy of predictive models used for estimating GHG emissions, and to determine to what extent choice of cultivar may have on GHG mitigation. We compared CH4 and N2O emissions, global warming potential (GWP = N2O + CH4), yield-scaled GWP (GWPY = GWP Mg-1 grain), and plant growth characteristics of 8 cultivars within 4 study sites in California and Arkansas. Seasonal CH4 emissions differed between cultivars by a factor of 2.1 and 1.3 at one California and one Arkansas site, respectively. Nitrous oxide emissions were negligible, comprised <10% of GWP, and were not different among cultivars. When sites and cultivars were pooled, and data were normalized to site averages, there was a positive correlation (r = 0.33) between root biomass at heading and seasonal CH4 emissions, but no correlation with shoot biomass at heading, or grain or straw biomass at maturity. Although differences in GWP and GWPY were observed, the consistency of some of the trends was variable across sites, indicating the importance of the genotype x environment interaction. While no high-yielding and low CH4-emitting cultivars were identified at the California sites, among the Southern varieties tested at the Arkansas site, the lowest emitting cultivar had the highest yield. This highlights the potential for breeding high-yielding varieties with low GWP, the ideal scenario to achieve low GWPY due to simultaneously mitigating GHG emissions and improving global food security.

  14. Simulating N2O emissions from irrigated cotton wheat rotations in Australia using DAYCENT: Mitigation options by optimized fertilizer and irrigation management

    NASA Astrophysics Data System (ADS)

    Scheer, Clemens; DelGrosso, Stephen; Parton, William; Rowlings, David; Grace, Peter

    2014-05-01

    Irrigation and fertilization do not only stimulate plant growth, but also accelerate microbial C- and N-turnover in the soil and thus can lead to enhanced emissions of nitrous oxide (N2O) from soils. In Australia there are more than 2 million hectares of agricultural land under irrigation and research has now focused on a combination of nitrogen fertilizer and irrigation management to maintain crop yields, maximize nitrogen use efficiency and reduce N2O emissions. Process-based models are now being used to estimate N2O emissions and assess mitigation options of N2O fluxes by improving management at field, regional and national scales. To insure that model predictions are reliable it is important to rigorously test the model so that uncertainty bounds for N2O emissions can be reduced and the impacts of different management practices on emissions can be better quantified. We used high temporal frequency dataset of N2O emissions to validate the performance of the agroecosystem model DayCent to simulate daily N2O emissions from sub-tropical vertisols under different irrigation intensities. Furthermore, we evaluated potential N2O mitigation strategies in irrigated cotton-wheat rotations in Australia by simulating different fertilizer and irrigation management scenarios over a climatically variable 25 year time span. DayCent accurately predicted soil moisture dynamics and the timing and magnitude of high fluxes associated with fertilizer additions and irrigation events. At the daily scale we found a good correlation of predicted vs. measured N2O fluxes (r2 = 0.52), confirming that DayCent can be used to test agricultural practices for mitigating N2O emission from irrigated cropping systems. The simulations of different fertilization and irrigation practices in cotton-wheat rotations over a 25 year time frame clearly showed that there is scope for reducing N2O emissions by modified fertilizer and irrigation management. For wheat and for cotton the model predicted that a

  15. Marinobacter strain NNA5, a newly isolated and highly efficient aerobic denitrifier with zero N2O emission.

    PubMed

    Liu, Ying; Ai, Guo-Min; Miao, Li-Li; Liu, Zhi-Pei

    2016-04-01

    An efficient aerobic denitrification bacterium, strain NNA5, was isolated and identified as Marinobacter sp. NNA5. NNA5 did not perform heterotrophic nitrification. GC/IRMS analysis revealed that (15)N2 was produced from Na(15)NO2 and K(15)NO3. GC/MS and quantitative analyses showed that no N2O emission occurred when nitrite or nitrate was used as substrate. Single factor experiments indicated that optimal conditions for aerobic denitrification were: sodium succinate or sodium pyruvate as carbon source, temperature 35 °C, NaCl concentration 2-4%, C/N ratio 6-8, pH 7.5, rotation speed 150 rpm (giving dissolved oxygen concentration 6.08 mg/L), NO3(-)-N concentration ranging from 140 to 700 mg/L. NNA5 displayed highly efficient aerobic denitrifying ability, with maximal NO3(-)-N removal rate 112.8 mg/L/d. In view of its ability to perform aerobic denitrification with zero N2O emission, NNA5 has great potential for future application in aerobic denitrification processes in industrial and aquaculture wastewater treatment systems. PMID:26836845

  16. [Effects of biochar on CO2 and N2O emissions and microbial properties of tea garden soils].

    PubMed

    Hu, Yun-fei; Li, Rong-lin; Yang, Yi-yang

    2015-07-01

    To clarify the effects of biochar addition (0.5%, 1.5%, 2.5%, 3.5%) on the emission of carbon dioxide (CO2) and nitrous oxide (N2O), pH and microbial communities of the tea garden soil, an indoor incubation experiment was conducted using the acidulated tea-planted soil. Results showed that the emissions of CO2 and N2O and the rate of C, N mineralization were increased in a short term after the addition of biochar compared with the control, while the promoting effect was weakened along with increasing the addition of biochar. The pH, dehydrogenase activity and microbial biomass carbon were increased in the biochar treatments. Phospholi-pid fatty acid (PLFA) with different markers was measured and the most PLFA was detected in the group in the 1.5% biochar treatment with significant differences (P<0.05) compared with the control. In addition, the higher levels of 16:0, 14:0 (bacteria), 18:lω9c (fungi), l0Me18:0 (actinomycetes) groups were observed and there were significant differences (P <0.05) in individual phospholipid fatty acid among the different treatments. Taken together, the acidulated tea-planted soil, soil microbial biomass and microbial number were improved after addition of biochar. PMID:26710619

  17. Combined use of nitrification inhibitor and struvite crystallization to reduce the NH3 and N2O emissions during composting.

    PubMed

    Jiang, Tao; Ma, Xuguang; Tang, Qiong; Yang, Juan; Li, Guoxue; Schuchardt, Frank

    2016-10-01

    Struvite crystallization (SCP) is combined with a nitrification inhibitor (dicyandiamide, DCD) to mitigate the NH3 and N2O emission during composting. The MgO and H3PO4 were added at a rate of 15% (mole/mole) of initial nitrogen, and the DCD was added at rates of 0%, 2.5%, 5.0%, 7.5% and 10% (w/w) of initial nitrogen respectively. Results showed that the combination use of SCP and DCD was phytotoxin free. The SCP could significantly reduce NH3 losses by 45-53%, but not the DCD. The DCD significantly inhibits nitrification when the content was higher than 50mgkg(-1), and that could reduce the N2O emission by 76.1-77.6%. The DCD degraded fast during the thermophilic phase, as the nitrification will be inhibited by the high temperature and high free ammonia content in this stage, the DCD was suggested to be applied in the maturing periods by 2.5% of initial nitrogen. PMID:26865057

  18. Inverse modelling of European CH4 and N2O emissions 2006-2012 using different inverse models and improved atmospheric observations

    NASA Astrophysics Data System (ADS)

    Bergamaschi, Peter; Karstens, Ute; Koffi, Ernest; Saunois, Marielle; Arnold, Timothy; Manning, Alistair; Tsuruta, Aki; Berchet, Antoine; Vermeulen, Alex; Janssens-Maenhout, Greet; Hammer, Samuel; Levin, Ingeborg; Schmidt, Martina

    2016-04-01

    We present top-down estimates of European CH4 and N2O emissions for 2006-2012, based on the new quality controlled and harmonized data set from 18 European atmospheric monitoring stations generated within the European FP7 project InGOS ("Integrated non-CO2 Greenhouse gas Observing System"). We applied an ensemble of 7 different inverse models for CH4 (and 4 for N2O), and performed four different inversion experiments, investigating the impact of different sets of stations and the use of 'a priori' information on emissions. The inverse models infer total CH4 emissions of 28.4 ± 6.4 (2σ) Tg CH4 yr‑1 for the EU-28 for 2006-2012 from the 4 inversion experiments. For comparison, total anthropogenic CH4 emissions reported to UNFCCC ('bottom-up', based on statistical data and emissions factors) amount to only 19.0 - 20.9 Tg CH4 yr‑1 for the same period. A potential explanation for the discrepancy between the 'bottom-up' and 'top-down' estimates could be the contribution of natural sources, such as peatlands, wetlands, and wet soils, which might have been underestimated in previous analyses. The hypothesis of significant natural emissions is supported by the finding that the inversions yield significant seasonal cycles of derived CH4 emissions with maximum in summer, while anthropogenic CH4 emissions are assumed to have much lower seasonal variability. Furthermore we investigate potential biases of the flux inversions by comparing model simulations with regular aircraft profiles at 4 European sites and the 'Infrastructure for Measurement of the European Carbon Cycle (IMECC)' aircraft campaign. For N2O, for which uncertainties of bottom-up inventories are very large - typically on the order of 100% for the total N2O emissions per country (mainly due to N2O emissions from agricultural soils) - our results demonstrate that atmospheric measurements and inverse modelling can significantly reduce the uncertainties. Despite the large uncertainties in the bottom

  19. Re-quantifying the emission factors based on field measurements and estimating the direct N2O emission from Chinese croplands

    NASA Astrophysics Data System (ADS)

    Zheng, Xunhua; Han, Shenghui; Huang, Yao; Wang, Yuesi; Wang, Mingxing

    2004-06-01

    The authors collect 54 direct N2O emission factors (EFds) obtained from 12 sites of Chinese croplands, of which 60% are underestimated by 29% and 30% are overestimated by 50% due to observation shortages. The biases of EFds are corrected and their uncertainties are re-estimated. Of the 31 site-scale EFds, 42% are lower by 58% and 26% are higher by 143% than the Intergovernmental Panel on Climate Change default. Periodically wetting/drying the fields or doubling nitrogen fertilizers may double or even triple an EFd. The direct N2O emission from Chinese croplands is estimated at 275 × 109 g N2O-N yr-1 in the 1990s, of which ˜20% is due to vegetable cultivation. The great uncertainty of this estimate, -79% to 135%, is overwhelmingly due to the huge uncertainty in estimating EFds (-78 ± 15% to 129 ± 62%). Direct N2O emission intensities significantly depend upon the economic situation of the region, implicating a larger potential emission in the future.

  20. Broadcast urea reduces N2O emissions but increases NO emissions compared with conventional and shallow-applied anhydrous ammonia in a coarse-textured soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantifying nitrous oxide (N2O) and nitric oxide (NO) fluxes from corn (Zea Mays L.) production fields under contrasting fertilizer regimes is essential for identifying ways of mitigating agricultural greenhouse gas (GHG) emissions. Despite the importance of anhydrous ammonia (AA) and urea as N fert...

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

    PubMed

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

    2014-01-01

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

  2. Ecological controls on N2O emission in surface litter and near-surface soil of a managed grassland: modelling and measurements

    NASA Astrophysics Data System (ADS)

    Grant, Robert F.; Neftel, Albrecht; Calanca, Pierluigi

    2016-06-01

    Large variability in N2O emissions from managed grasslands may occur because most emissions originate in surface litter or near-surface soil where variability in soil water content (θ) and temperature (Ts) is greatest. To determine whether temporal variability in θ and Ts of surface litter and near-surface soil could explain this in N2O emissions, a simulation experiment was conducted with ecosys, a comprehensive mathematical model of terrestrial ecosystems in which processes governing N2O emissions were represented at high temporal and spatial resolution. Model performance was verified by comparing N2O emissions, CO2 and energy exchange, and θ and Ts modelled by ecosys with those measured by automated chambers, eddy covariance (EC) and soil sensors on an hourly timescale during several emission events from 2004 to 2009 in an intensively managed pasture at Oensingen, Switzerland. Both modelled and measured events were induced by precipitation following harvesting and subsequent fertilizing or manuring. These events were brief (2-5 days) with maximum N2O effluxes that varied from < 1 mgNm-2h-1 in early spring and autumn to > 3 mgNm-2h-1 in summer. Only very small emissions were modelled or measured outside these events. In the model, emissions were generated almost entirely in surface litter or near-surface (0-2 cm) soil, at rates driven by N availability with fertilization vs. N uptake with grassland regrowth and by O2 supply controlled by litter and soil wetting relative to O2 demand from microbial respiration. In the model, NOx availability relative to O2 limitation governed both the reduction of more oxidized electron acceptors to N2O and the reduction of N2O to N2, so that the magnitude of N2O

  3. Reviews and syntheses: Soil N2O and NO emissions from land use and land-use change in the tropics and subtropics: a meta-analysis

    NASA Astrophysics Data System (ADS)

    van Lent, J.; Hergoualc'h, K.; Verchot, L. V.

    2015-12-01

    Deforestation and forest degradation in the tropics may substantially alter soil N-oxide emissions. It is particularly relevant to accurately quantify those changes to properly account for them in a REDD+ climate change mitigation scheme that provides financial incentives to reduce the emissions. With this study we provide updated land use (LU)-based emission rates (104 studies, 392 N2O and 111 NO case studies), we determine the trend and magnitude of flux changes with land-use change (LUC) using a meta-analysis approach (44 studies, 135 N2O and 37 NO cases) and evaluate biophysical drivers of N2O and NO emissions and emission changes for the tropics. The average N2O and NO emissions in intact upland tropical forest amounted to 2.0 ± 0.2 (n = 90) and 1.7 ± 0.5 (n = 36) kg N ha-1 yr-1, respectively. In agricultural soils annual N2O emissions were exponentially related to N fertilization rates and average water-filled pore space (WFPS) whereas in non-agricultural sites a Gaussian response to WFPS fit better with the observed NO and N2O emissions. The sum of soil N2O and NO fluxes and the ratio of N2O to NO increased exponentially and significantly with increasing nitrogen availability (expressed as NO3- / [NO3-+NH4+]) and WFPS, respectively; following the conceptual Hole-In-the-Pipe model. Nitrous and nitric oxide fluxes did not increase significantly overall as a result of LUC (Hedges's d of 0.11 ± 0.11 and 0.16 ± 0.19, respectively), however individual LUC trajectories or practices did. Nitrous oxide fluxes increased significantly after intact upland forest conversion to croplands (Hedges's d = 0.78 ± 0.24) and NO increased significantly following the conversion of low forest cover (secondary forest younger than 30 years, woodlands, shrublands) (Hedges's d of 0.44 ± 0.13). Forest conversion to fertilized systems significantly and highly raised both N2O and NO emission rates (Hedges's d of 1.03 ± 0.23 and 0.52 ± 0.09, respectively). Changes in nitrogen

  4. Soil N2O and NO emissions from land use and land-use change in the tropics and subtropics: a meta-analysis

    NASA Astrophysics Data System (ADS)

    van Lent, J.; Hergoualc'h, K.; Verchot, L. V.

    2015-08-01

    Deforestation and forest degradation in the tropics may substantially alter soil N-oxide emissions. It is particularly relevant to accurately quantify those changes to properly account for them in a REDD+ climate change mitigation scheme that provides financial incentives to reduce the emissions. With this study we provide updated land use (LU)-based emission rates (103 studies, 387 N2O and 111 NO case studies), determine the trend and magnitude of flux changes with land-use change (LUC) using a meta-analysis approach (43 studies, 132 N2O and 37 NO cases) and evaluate biophysical drivers of N2O and NO emissions and emission changes for the tropics. The average N2O and NO emissions in intact upland tropical forest amounted to 2.0 ± 0.2 (n = 88) and 1.7 ± 0.5 (n = 36) kg N ha-1 yr-1, respectively. In agricultural soils annual N2O emissions were exponentially related to N fertilization rates and average water-filled pore space (WFPS) whereas in non-agricultural sites a Gaussian response to WFPS fit better the observed NO and N2O emissions. The sum of soil N2O and NO fluxes and the ratio of N2O to NO increased exponentially and significantly with increasing nitrogen availability (expressed as NO3-/[NO3-+NH4+]) and WFPS, respectively; following the conceptual Hole-In-the-Pipe model. Nitrous and nitric oxide fluxes did not overall increase significantly as a result of LUC (Hedges's d of 0.11 ± 0.11 and 0.16 ± 0.19, respectively), however individual LUC trajectories or practices did. Nitrous oxide fluxes increased significantly after intact upland forest conversion to croplands (Hedges's d = 0.78 ± 0.24) and NO increased significantly following the conversion of low forest cover (secondary forest younger than 30 years, woodlands, shrublands) (Hedges's d of 0.44 ± 0.13). Forest conversion to fertilized systems significantly and highly raised both N2O and NO emission rates (Hedges's d of 1.03 ± 0.23 and 0.52 ± 0.09, respectively). Changes in nitrogen availability

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  6. N2O EMISSIONS FROM STREAMS IN THE NEUSE RIVER WATERSHED, NORTH CAROLINA

    EPA Science Inventory

    The paper presents N2O emission data from 11 sites in the Neuse River watershed. Emissions were measured using a static surface enclosure technique deployed on eight sites on the main river channel and three tributary sites. Ancillary data collected included dissolved ...

  7. Atmospheric Emissions of N2O, CH4, and CO2 from Different Nitrogen Fertilizers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is a growing interest in quantification of significant sources of greenhouse gas (GHG) emissions from agricultural practices. Efficient N fertilizers and alternative sources of N that produce low GHG emissions from soil are needed to reduce the impact of agricultural practices on global warmin...

  8. Reducing fertilizer-derived N2O emission: Point injection vs. surface application of ammonium-N fertilizer at a loamy sand site

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    N2O emitted from soil originates either from denitrification of nitrate and/or nitrification of ammonium. N fertilization can have an important impact on N2O emission rates. Injection of nitrate-free ammonium-N fertilizer, in Germany also known as CULTAN (Controlled Uptake Long-Term Ammonium Nutrition), results in fertilizer depots with ammonium concentrations of up to 10 mg N g-1 soil-1. High concentrations of ammonium are known to inhibit nitrification. However, it has not yet been clarified how N2O fluxes are affected by CULTAN. In a field experiment, two application methods of nitrogen fertilizer were used at a loamy sand site: Ammonium sulphate was applied either by point injection or by surface application. 15N-ammonium sulphate was used to distinguish between N2O originating from either fertilizer-N or soil-N. Unfertilized plots and plots fertilized with unlabeled ammonium sulphate served as control. N2O emissions were measured using static chambers, nitrate and ammonium concentrations were determined in soil extracts. Stable isotope analysis of 15N in N2O, nitrate and ammonium was used to calculate the contribution of fertilizer N to N2O emissions and the fertilizer turnover in soil. 15N analysis clearly indicated that fertilizer derived N2O fluxes were higher from surface application plots. For the period of the growing season, about 24% of the flux measured in surface application treatment and less than 10% from injection treatment plots originated from the fertilizer. In addition, a lab experiment was conducted to gain insight into processes leading to N2O emission from fertilizer depots. One aim was to examine whether the ratio of N2O to nitrate formation differs depending on the ammonium concentration. Loamy sand soil was incubated in microcosms continuously flushed with air under conditions favouring nitrification. 15N-labeled nitrate was used to differentiate between nitrification and denitrification. Stable isotope analyses of 15N were performed on

  9. The emissions and soil concentrations of N2O and CH4 from natural soil temperature gradients in a volcanic area in southwest Iceland

    NASA Astrophysics Data System (ADS)

    Maljanen, Marja; Yli-Moijala, Heli; Leblans, Niki I. W.; De Boeck, Hans J.; Bjarnadóttir, Brynhildur; Sigurdsson, Bjarni D.

    2016-04-01

    We studied nitrous oxide (N2O) and methane (CH4) emissions along three natural geothermal soil temperature (Ts) gradients in a volcanic area in southwest Iceland. Two of the gradients (on a grassland and a forest site, respectively) were recently formed (in May 2008). The third gradient, a grassland site, had been subjected to long-term soil warming (over 30 years, and probably centuries). Nitrous oxide and methane emissions were measured along the temperature gradients using the static chamber method and also soil gas concentrations were studied. With a moderate soil temperature increase (up to +5 °C) there were no significant increase in gas flux rates in any of the sites but an increase of 20 to 45 °C induced an increase in both N2O and CH4 emissions. The measured N2O emissions (up to 2600 μg N2O m-2 h-1) from the warmest plots were about two magnitudes higher compared with the coolest plots (less than 20 μg N2O m-2 h-1). While a net uptake of CH4 was measured in the coolest plots (up to -0.15 mg CH4 m-2 h-1), a net emission of CH4 was measured from the warmest plots (up to 1.3 mg CH4 m-2 h-1). Soil CH4 concentrations decreased first with a moderate (up to +5 °C) increase in Ts, but above that threshold increased significantly. The soil N2O concentration at depths from 5 to 20 cm increased with increasing Ts, indicating enhanced N-turnover. Further, there was a clear decrease in soil organic matter (SOM), C- and N concentration with increasing Ts at all sites. One should note, however, that a part of the N2O emitted from the warmest plots may be partly geothermally derived, as was revealed by 15N2O isotope studies. These natural Ts gradients show that the emission of N2O and CH4 can increase significantly when Ts increases considerably. This implies that these geothermally active sites can act as local hot spots for CH4 and N2O emissions.

  10. Insights into the Effect of Soil pH on N2O and N2 Emissions and Denitrifier Community Size and Activity ▿

    PubMed Central

    Čuhel, Jiří; Šimek, Miloslav; Laughlin, Ronnie J.; Bru, David; Chèneby, Dominique; Watson, Catherine J.; Philippot, Laurent

    2010-01-01

    The objective of this study was to investigate how changes in soil pH affect the N2O and N2 emissions, denitrification activity, and size of a denitrifier community. We established a field experiment, situated in a grassland area, which consisted of three treatments which were repeatedly amended with a KOH solution (alkaline soil), an H2SO4 solution (acidic soil), or water (natural pH soil) over 10 months. At the site, we determined field N2O and N2 emissions using the 15N gas flux method and collected soil samples for the measurement of potential denitrification activity and quantification of the size of the denitrifying community by quantitative PCR of the narG, napA, nirS, nirK, and nosZ denitrification genes. Overall, our results indicate that soil pH is of importance in determining the nature of denitrification end products. Thus, we found that the N2O/(N2O + N2) ratio increased with decreasing pH due to changes in the total denitrification activity, while no changes in N2O production were observed. Denitrification activity and N2O emissions measured under laboratory conditions were correlated with N fluxes in situ and therefore reflected treatment differences in the field. The size of the denitrifying community was uncoupled from in situ N fluxes, but potential denitrification was correlated with the count of NirS denitrifiers. Significant relationships were observed between nirS, napA, and narG gene copy numbers and the N2O/(N2O + N2) ratio, which are difficult to explain. However, this highlights the need for further studies combining analysis of denitrifier ecology and quantification of denitrification end products for a comprehensive understanding of the regulation of N fluxes by denitrification. PMID:20118356

  11. Indirect emissions and isotopologue signatures of N2O from agricultural drainage water of a Pleistocene lowland catchment in North-Eastern Germany

    NASA Astrophysics Data System (ADS)

    Weymann, D.; Well, R.; Kahle, P.; Tiemeyer, B.; Flessa, H.

    2011-12-01

    Artificial drainage of low- and wetlands is a common practice in many agricultural regions to facilitate crop production. Agricultural drainage water was shown to be supersaturated with nitrous oxide (N2O), a major greenhouse gas thought to contribute to global warming and to the destruction of stratospheric ozone. Therefore, drainage of agricultural land has potential for indirect N2O emissions which are a highly uncertain component of the global N2O budget. This case study focuses on these emissions and further tries to unravel the source processes of N2O as well as the impact of its hydrological controls by applying an isotopologue approach. The research area was an intensively tile drained agricultural catchment embedded in the Pleistocene lowland of the federal state Mecklenburg-Vorpommern (North-Eastern Germany). Water sampling was conducted during the consecutive hydrological winter periods 2007/2008 and 2008/2009 by sampling a collector drain outlet and an adjacent drainage ditch. Besides concentrations of dissolved N2O and NO3- we determined the isotopologue signatures of N2O by measuring δ15Nbulk and δ18O as well as the 15N 'site preference', which characterizes the intramolecular distribution of the N isotopes within the asymmetric N2O molecule and is a promising tool to distinguish between the main source processes of N2O, nitrification and denitrification. The investigated hydrological winter periods varied considerably concerning the weather and hydrological conditions. During the comparatively wet winter period 2007/2008, indirect N2O emissions accounted for 0.17 kg N2O-N ha-1 a-1 and were thus higher than during the colder and comparatively dry 2008/2009 period, where we found 0.12 kg N2O-N ha-1 a-1. The emission factors for both sampling periods were 0.23 % and 0.17 % of the N input, respectively, and therefore in good agreement with the current IPCC default value of 0.25 %. The isotopologue signatures of N2O reflected the different hydrological

  12. [Effects of different fertilization measures on N2O emission in oil sunflower field in irrigation area of upper Yellow River].

    PubMed

    Chen, Zhe; Chen, Yuan-yuan; Gao, Ji; Liu, Ru-liang; Yang, Zheng-li; Zhang, Ai-ping

    2015-01-01

    Agricultural soil has become the largest anthropogenic source of atmospheric nitrous oxide (N20). To estimate the impacts of long-term combined application of organic and inorganic fertilizers on N20 emission in a typical winter wheat-oil sunflower cropping system in the Ningxia irrigation area, we measured N20 fluxes using the static opaque chamber-gas chromatograph method and monitored the seasonal dynamics of related factors. Our results showed that nitrogen addition in the previous crop field significantly stimulated N2O emissions during the following oil-sunflower cultivation, and the mean fluxes of N300-OM, N240-OM1/2, N300 and N240 were (34.16 ± 9.72), (39.69 ±10.70), (27.75 ±9.57) and (26.30 ± 8.52) µg . m-2 . h-1, respectively, which were 4.09, 4.75, 3.32 and 3.15 times of the control groups. The total cumulative N2O emissions of fertilizer treatments in growing season was as high as 796.7 to 1242.5 g . hm-2, which was 2.99 to 4.67 times of the control groups. During the growing season, the rates of N2O emission in each month organic and inorganic fertlizers combined treatments were similar at high levels. N2O emission in chemical fertilizer treatments gradually decreased, and the main period of N2O emission occurred at the beginning of growing season. Taking July for example, N2O emission accounted for 41.3% to 41. 8% of total cumulative amount. The amounts of N20 emission under organic and inorganic fertilizers combined treatments were significantly higher than under chemical fertilizer treatments. The N2O emissions were not significantly different between conventional and optimized applications of nitrogen fertilizer under the same fertilizing method, either between N300-OM and N240-OM1/2, or between N300 and N240. On account of the drought, N2O emission in each treatment was mainly affected by soil moisture. N2O emission had a significant positive correlation with soil ammonium nitrogen content under combined applications of organic and inorganic

  13. BOREAS TGB-5 Biogenic Soil Emissions of NO and N2O

    NASA Technical Reports Server (NTRS)

    Levine, J. S.; Winstead, E. L.; Parsons, D. A. B.; Scholes, M. C.; Cofer, W. R.; Cahoon, D. R.; Sebacher, D. I.; Scholes, R. J.; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor)

    2000-01-01

    The BOReal Ecosystem-Atmosphere Study Trace Gas Biogeochemistry (BOREAS TGB)-5 team made several measurements of trace gas concentrations and fluxes at various NSA sites. This data set contains biogenic soil emissions of nitric oxide and nitrous oxide that were measured over a wide range of spatial and temporal site parameters. Since very little is known about biogenic soil emissions of nitric oxide and nitrous oxide from the boreal forest, the goal of the measurements was to characterize the biogenic soil fluxes of nitric oxide and nitrous oxide from black spruce and jack pine areas in the boreal forest. The diurnal variation and monthly variation of the emissions was examined as well as the impact of wetting through natural or artificial means. Temporally, the data cover mid-August 1993, June to August 1994, and mid-July 1995. The data are provided in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884).

  14. Seasonal Dynamics of N2O and CO2 Emissions from a Corn Production System measured with the Eddy covariance and Chamber techniques

    NASA Astrophysics Data System (ADS)

    Iwuozo, S. A.; Hui, D.; Dennis, S.

    2013-12-01

    Agricultural Practices play a major role in the global fluxes of the greenhouse gases carbon dioxide, nitrous oxide, and methane. The use of fertilizer in Corn production has generated concerns about its contribution to global climate change. Thus, farmers and others concerned have become interested in more efficient fertilization management practice and reduced greenhouse gas emissions. To understand best management practices, in the 2012 and 2013 corn growing seasons, field experiments was conducted at Tennessee State University Agricultural Research and Demonstration Center in Nashville, TN. The study examines the seasonal variations of (N2O) and (CO2) emissions from soil as a function of six treatment that include inorganic nitrogen fertilizer, chicken litter and biochar application. The combinations were: regular URAN 32-0-0 liquid fertilizer (2 times) no till, regular URAN 32-0-0 liquid fertilizer (2 times) conventional till, multiple URAN applications (4 times) no till, Denitrification inhibitor with regular URAN application in no till, chicken litter with regular URAN application no till and URAN application with biochar in no tilled plots. Each treatment was replicated 6 times. N2O and CO2 emissions were measured using a closed chamber method after rainfall event(s), fertilizer applications or every two weeks whichever was shorter. Corresponding soil NH4+-N and NO3--N, soil temperature and moisture were also measured during gas sampling. Plant physiological and growth parameters were measured as appropriate and meteorological records were kept. N2O flux was also continuously measured in a commercial corn field using the eddy covariance (EC) technique fitted with a fast response N2O analyzer to check the N2O emissions at the large scale and compare it to the chamber method. Results obtained with the EC technique were comparable with the chamber methods. Preliminary data indicate that N2O and CO2 fluxes were significantly influenced by the agricultural

  15. Emissions of CO2 and N2O From Three Potato Systems in Maine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Estimating greenhouse gas (GHG) emissions and soil carbon sequestration requires measurements be made within different crop production systems. A long-term potato cropping system experiment established in 2004 in Presque Isle, ME, on a sandy loam soil addresses three scenarios [ 1) Business as Usua...

  16. DAYCENT NATIONAL SCALE SIMULATIONS OF N2O EMISSIONS FROM CROPPED SOILS IN THE USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Until recently, Intergovernmental Panel on Climate Change (IPCC) emission factor methodology, based on simple empirical relationships, has been used to estimate carbon (C) and nitrogen (N) fluxes for regional and national inventories. However, the 2005 US Environmental Protection Agency (EPA) greenh...

  17. Assessing fertilizer N placement on CH4 and N2O emissions in irrigated rice systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improved N fertilizer management practices can increase rice yields and mitigate global warming potential (GWP). While banding N has been shown to have positive effects on yield and nitrogen use efficiency (NUE), there is little information in how it affects greenhouse gas (GHG) emissions from flood...

  18. High-Resolution Denitrification Kinetics in Pasture Soils Link N2O Emissions to pH, and Denitrification to C Mineralization

    PubMed Central

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

    2016-01-01

    Denitrification in pasture soils is mediated by microbial and physicochemical processes leading to nitrogen loss through the emission of N2O and N2. It is known that N2O reduction to N2 is impaired by low soil pH yet controversy remains as inconsistent use of soil pH measurement methods by researchers, and differences in analytical methods between studies, undermine direct comparison of results. In addition, the link between denitrification and N2O emissions in response to carbon (C) mineralization and pH in different pasture soils is still not well described. We hypothesized that potential denitrification rate and aerobic respiration rate would be positively associated with soils. This relationship was predicted to be more robust when a high resolution analysis is performed as opposed to a single time point comparison. We tested this by characterizing 13 different temperate pasture soils from northern and southern hemispheres sites (Ireland and New Zealand) using a fully automated-high-resolution GC detection system that allowed us to detect a wide range of gas emissions simultaneously. We also compared the impact of using different extractants for determining pH on our conclusions. In all pH measurements, soil pH was strongly and negatively associated with both N2O production index (IN2O) and N2O/(N2O+N2) product ratio. Furthermore, emission kinetics across all soils revealed that the denitrification rates under anoxic conditions (NO+N2O+N2 μmol N/h/vial) were significantly associated with C mineralization (CO2 μmol/h/vial) measured both under oxic (r2 = 0.62, p = 0.0015) and anoxic (r2 = 0.89, p<0.0001) conditions. PMID:26990862

  19. High-Resolution Denitrification Kinetics in Pasture Soils Link N2O Emissions to pH, and Denitrification to C Mineralization.

    PubMed

    Samad, Md Sainur; Bakken, Lars R; Nadeem, Shahid; Clough, Timothy J; de Klein, Cecile A M; Richards, Karl G; Lanigan, Gary J; Morales, Sergio E

    2016-01-01

    Denitrification in pasture soils is mediated by microbial and physicochemical processes leading to nitrogen loss through the emission of N2O and N2. It is known that N2O reduction to N2 is impaired by low soil pH yet controversy remains as inconsistent use of soil pH measurement methods by researchers, and differences in analytical methods between studies, undermine direct comparison of results. In addition, the link between denitrification and N2O emissions in response to carbon (C) mineralization and pH in different pasture soils is still not well described. We hypothesized that potential denitrification rate and aerobic respiration rate would be positively associated with soils. This relationship was predicted to be more robust when a high resolution analysis is performed as opposed to a single time point comparison. We tested this by characterizing 13 different temperate pasture soils from northern and southern hemispheres sites (Ireland and New Zealand) using a fully automated-high-resolution GC detection system that allowed us to detect a wide range of gas emissions simultaneously. We also compared the impact of using different extractants for determining pH on our conclusions. In all pH measurements, soil pH was strongly and negatively associated with both N2O production index (IN2O) and N2O/(N2O+N2) product ratio. Furthermore, emission kinetics across all soils revealed that the denitrification rates under anoxic conditions (NO+N2O+N2 μmol N/h/vial) were significantly associated with C mineralization (CO2 μmol/h/vial) measured both under oxic (r2 = 0.62, p = 0.0015) and anoxic (r2 = 0.89, p<0.0001) conditions. PMID:26990862

  20. Effect of mowing on N2O and CH4 fluxes emissions from the meadow-steppe grasslands of Inner Mongolia

    NASA Astrophysics Data System (ADS)

    Lu, Zedong; Du, Rui; Du, Pengrui; Li, Ziming; Liang, Zongmin; Wang, Yaling; Qin, Saisai; Zhong, Lei

    2015-09-01

    To assess the impacts of mowing on N2O and CH4 fluxes emissions from the meadow-steppe grasslands of Inner Mongolia, China, two regimes were investigated: unmown since 2005 (UM), and mown once every three years since 2009 (M3). On-site measurements were conducted continuously during a year-round period (August 2011 to August 2012). During the observation period, three diurnal cycles were also measured. In addition, a targeted laboratory experiment was conducted to make up for the few measurements in winter. A large pulse of N2O emissions related to freeze-thaw cycles was observed at M3 during the spring thaw. Results showed that the meadow-steppes played a role as a sink for CH4 and a source for N2O. Significantly lower mean CH4 uptake at UM (40.3 μg C·m-2·h-1) as compared to M3 (70.5 μg C ·m-2·h-1) ( p<0.01), and significantly higher mean N2O efflux at UM (6.3 μgN·m-2·h-1) as compared to M3 (4.3 μg N·m-2·h-1) ( p<0.05) were found. The laboratory experiment results revealed that mowing changed the soil conditions that favor the activity of denitrifiers during thawing periods. The CH4 and N2O fluxes were significantly correlated with soil temperature ( p<0.05). Mowing affected CH4 uptake and N2O emission mainly through its effect on vegetation types and some soil properties, such as soil inorganic N content, soil temperature, and soil moisture content, while soil inorganic N and moisture were not leading factors. Our results also suggested that mowing could mitigate the potential global warming in terms of CH4 uptake and N2O emissions.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  2. Two years monitoring of soil N_{2}O emissions on durum wheat in a Mediterranean area: the effect of tillage intensity and N-fertilizer rate.

    NASA Astrophysics Data System (ADS)

    Volpi, Iride; Bosco, Simona; Triana, Federico; Di Nasso, Nicoletta Nassi o.; Laville, Patricia; Virgili, Giorgio; Bonari, Enrico

    2016-04-01

    Evaluating the magnitude and the key factors affecting N2O emissions from agriculture has a scientific and practical relevance, in fact emissions from agricultural and natural soils account for 56-70% of all global N2O sources (Syakila and Kroeze, 2011). Moreover, the necessity to increase the food production rate minimizing greenhouse gas emissions require a deeper understanding of the effect of the agricultural practices on direct soil emissions. Therefore, the aim of this work is to assess the effect of tillage intensity and nitrogen rate on soil N2O emissions on durum wheat. A two years monitoring campaign was carried out using a high-sensibility transportable instrument developed within the LIFE+ "Improved flux Prototypes for N2O emission from Agriculture" IPNOA project (Bosco et al., 2015; Laville et al., 2015). The project aims at improving the measurement technique of N2O flux directly in field using the flow-through non-steady state chamber technique. The monitoring campaign on durum wheat lasted for two growing seasons and two fallow periods (2013-14 and 2014-15). Treatment on the main plot was tillage intensity with two levels, ploughing and minimum tillage, and three different nitrogen rates were distributed to the subplots (N0: 0 kg ha‑1, N1: 110 kg ha‑1, N2: 170 kg ha‑1). Ancillary measurements concerned meteorological data, soil temperature and moisture, NO3‑, NH4+ soil concentration. Main results of the two years highlighted N rate as the main driver for both N2O daily flux and cumulative emissions during the growing season, while in the fallow period treatments did not affect the emission magnitude. Tillage intensity was not a key factor for N2O emissions. N2O emissions were significantly different in the two years. In particular, cumulative emissions of 2013-14 were about five times higher than in 2014-15, respectively on average 2885±260 g N-N2O ha‑1 and 534±53 g N-N2O ha‑1 for a similar monitoring period of about 300 days

  3. [Effects of dicyandiamide combined with nitrogen fertilizer on N2O emission and economic benefit in winter wheat and summer maize rotation system].

    PubMed

    Wang, Yan-qun; Li, Ying-chun; Peng, Zheng-ping; Wang, Chao-dong; Liu, Ya-nan

    2015-07-01

    Aiming at the problems of excessive and unreasonable fertilizer application, lower nitrogen use efficiency, increasing N2O emission from soil and fertilizer in current intensified agricultural productions, a field experiment was conducted to study the effects of dicyandiamide (DCD) combined with nitrogen fertilizer application at different levels, i.e., 150, 225, 300 kg . hm-2, on N20 emission and relevant economic benefit in a typical winter wheat-summer maize rotation system in North China Plain. The results showed that DCD application decreased N2O emission fluxes and cumulative emissions by 25.6%-32.1% and 23.1%-31.1% in the year-round. There was a significant positive exponential correlation between N2O flux and soil surface temperature or soil moisture content. The effect of soil moisture on N2O emission was stronger in wheat season than in maize season, while the effect of temperature on N2O emission was on the contrary. The yields of winter wheat and summer maize with DCD addition were increased by 16.7%-24.6% and 29.8%-34.5%, respectively, and the average economic income of two seasons was increased by 7973.2 yuan . hm-2. Therefore, appropriate rate of N fertilizer combined with DCD could not only increase crop yield and economic income, but also reduce N2O emission. Considering environmental and economic benefit under this experimental condition, DCD combined with nitrogen of moderate level (total N amount 225 kg . hm-2) was a good nitrogen management mode in North China. PMID:26710625

  4. CH4 and N2O emissions from China's beef feedlots with ad libitum and restricted feeding in fall and spring seasons.

    PubMed

    Lin, Zhi; Liao, Wenhua; Yang, Yuanyuan; Gao, Zhiling; Ma, Wenqi; Wang, Dianwu; Cao, Yufeng; Li, Jianguo; Cai, Zhenjiang

    2015-04-01

    Accurately quantifying methane (CH4) and nitrous oxide (N2O) emissions from beef operations in China is necessary to evaluate the contribution of beef cattle to greenhouse gas budgets at the national and global level. Methane and N2O emissions from two intensive beef feedlots in the North China Plain, one with a restricted feeding strategy and high manure collection frequency and the other with an ad libitum feeding strategy and low manure collection frequency, were quantified in the fall and spring seasons using an inverse dispersion technique. The diel pattern of CH4 from the beef feedlot with an ad libitum feed strategy (single peak during a day) differed from that under a restricted feeding condition (multiple peaks during a day), but little difference in the diel pattern of N2O emissions between two feeding strategies was observed. The two-season average CH4 emission rates of the two intensive feedlots were 230 and 198gCH4animal(-1)d(-1) and accounted for 6.7% and 6.8% of the gross energy intake, respectively, indicating little impact of the feeding strategy and manure collection frequency on the CH4 conversion factor at the feedlot level. However, the average N2O emission rates (21.2g N2Oanimal(-1)d(-1)) and conversion factor (8.5%) of the feedlot with low manure collection frequency were approximately 131% and 174% greater, respectively, than the feedlot under high frequency conditions, which had a N2O emission rate and conversion factor of 9.2g N2Oanimal(-1)d(-1) and 3.1%, respectively, indicating that increasing manure collection frequency played an important role in reducing N2O emissions from beef feedlots. In addition, comparison indicated that China's beef and dairy cattle in feedlots appeared to have similar CH4 conversion factors. PMID:25769128

  5. Pig slurry acidification and separation techniques affect soil N and C turnover and N2O emissions from solid, liquid and biochar fractions.

    PubMed

    Gómez-Muñoz, B; Case, S D C; Jensen, L S

    2016-03-01

    The combined effects of pig slurry acidification, subsequent separation techniques and biochar production from the solid fraction on N mineralisation and N2O and CO2 emissions in soil were investigated in an incubation experiment. Acidification of pig slurry increased N availability from the separated solid fractions in soil, but did not affect N2O and CO2 emissions. However acidification reduced soil N and C turnover from the liquid fraction. The use of more advanced separation techniques (flocculation and drainage > decanting centrifuge > screw press) increased N mineralisation from acidified solid fractions, but also increased N2O and CO2 emissions in soil amended with the liquid fraction. Finally, the biochar production from the solid fraction of pig slurry resulted in a very recalcitrant material, which reduced N and C mineralisation in soil compared to the raw solid fractions. PMID:26716355

  6. Emissions of CH4 and N2O under Different Tillage Systems from Double-Cropped Paddy Fields in Southern China

    PubMed Central

    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

  7. 40 CFR 1037.104 - Exhaust emission standards for CO2, CH4, and N2O for heavy-duty vehicles at or below 14,000...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... emission standards for one or more test groups, consistent with the provisions of 40 CFR 86.1818. To do... adjust the calculated emissions by the global warming potential (GWP): GWP equals 25 for CH4 and 298 for... 298 Mg of positive CO2 credits to offset 1 Mg of negative N2O credits. Note that 40 CFR...

  8. 40 CFR 1037.104 - Exhaust emission standards for CO2, CH4, and N2O for heavy-duty vehicles at or below 14,000...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... provisions of 40 CFR 86.1818. To do this, calculate the CH4 and/or N2O emission credits needed (negative... certification. You must adjust the calculated emissions by the global warming potential (GWP): GWP equals 25 for... CFR 86.1818-12(f) does not apply for vehicles subject to the standards of this section....

  9. 40 CFR 1037.104 - Exhaust emission standards for CO2, CH4, and N2O for heavy-duty vehicles at or below 14,000...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... emission standards for one or more test groups, consistent with the provisions of 40 CFR 86.1818. To do... adjust the calculated emissions by the global warming potential (GWP): GWP equals 25 for CH4 and 298 for... 298 Mg of positive CO2 credits to offset 1 Mg of negative N2O credits. Note that 40 CFR...

  10. Alternate wetting and drying of rice reduced CH4 emissions but triggered N2O peaks in a clayey soil of central Italy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reducing CH4 and N2O emissions from rice cropping systems while sustaining production levels with less water requires a better understanding of the key processes involved. Alternate wetting and drying (AWD) irrigation is one promising practice that has been shown to reduce CH4 emissions. However, li...

  11. Alternate wetting and drying of rice reduced CH4 emissions but triggered N2O peaks in a clayey soil of central Italy.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reducing CH4 and N2O emissions from rice cropping systems while sustaining production levels with less water requires a better understanding of the key processes involved. Alternate wetting and drying (AWD) irrigation is one promising practice that has been shown to reduce CH4 emissions. However, li...

  12. A modeling study on mitigation of N2O emissions and NO3 leaching at different agricultural sites across Europe using LandscapeDNDC.

    PubMed

    Molina-Herrera, Saúl; Haas, Edwin; Klatt, Steffen; Kraus, David; Augustin, Jürgen; Magliulo, Vincenzo; Tallec, Tiphaine; Ceschia, Eric; Ammann, Christof; Loubet, Benjamin; Skiba, Ute; Jones, Stephanie; Brümmer, Christian; Butterbach-Bahl, Klaus; Kiese, Ralf

    2016-05-15

    The identification of site-specific agricultural management practices in order to maximize yield while minimizing environmental nitrogen losses remains in the center of environmental pollution research. Here, we used the biogeochemical model LandscapeDNDC to explore different agricultural practices with regard to their potential to reduce soil N2O emissions and NO3 leaching while maintaining yields. In a first step, the model was tested against observations of N2O emissions, NO3 leaching, soil micrometeorology as well as crop growth for eight European cropland and grassland sites. Across sites, LandscapeDNDC predicts very well mean N2O emissions (r(2)=0.99) and simulates the magnitude and general temporal dynamics of soil inorganic nitrogen pools. For the assessment of site-specific mitigation potentials of environmental nitrogen losses a Monte Carlo optimization technique considering different agricultural management options (i.e., timing of planting, harvest and fertilization, amount of applied fertilizer as well as residue management) was used. The identified optimized field management practices reduce N2O emissions and NO3 leaching from croplands on average by 21% and 31%, respectively. Likewise, average reductions of 55% for N2O emissions and 16% for NO3 leaching are estimated for grasslands. For mitigating environmental loss - while maintaining yield levels - it was most important to reduce fertilizer application rates by in average 10%. Our analyses indicate that yield scaled N2O emissions and NO3 leaching indicate possible improvements of nitrogen use efficiencies in European farming systems. Moreover, the applied optimization approach can be used also in a prognostic way to predict optimal timings and fertilization options (rates and splitting) upon accurate weather forecasts combined with the knowledge of modeled soil nutrient availability and plant nitrogen demand. PMID:26909705

  13. Sensitivity analysis for models of greenhouse gas emissions at farm level. Case study of N(2)O emissions simulated by the CERES-EGC model.

    PubMed

    Drouet, J-L; Capian, N; Fiorelli, J-L; Blanfort, V; Capitaine, M; Duretz, S; Gabrielle, B; Martin, R; Lardy, R; Cellier, P; Soussana, J-F

    2011-11-01

    Modelling complex systems such as farms often requires quantification of a large number of input factors. Sensitivity analyses are useful to reduce the number of input factors that are required to be measured or estimated accurately. Three methods of sensitivity analysis (the Morris method, the rank regression and correlation method and the Extended Fourier Amplitude Sensitivity Test method) were compared in the case of the CERES-EGC model applied to crops of a dairy farm. The qualitative Morris method provided a screening of the input factors. The two other quantitative methods were used to investigate more thoroughly the effects of input factors on output variables. Despite differences in terms of concepts and assumptions, the three methods provided similar results. Among the 44 factors under study, N(2)O emissions were mainly sensitive to the fraction of N(2)O emitted during denitrification, the maximum rate of nitrification, the soil bulk density and the cropland area. PMID:21296472

  14. N2O, NO, N2 and CO2 emissions from tropical savanna and grassland of northern Australia: an incubation experiment with intact soil cores

    NASA Astrophysics Data System (ADS)

    Werner, C.; Reiser, K.; Dannenmann, M.; Hutley, L. B.; Jacobeit, J.; Butterbach-Bahl, K.

    2014-11-01

    Strong seasonal variability of hygric and thermal soil conditions are a defining environmental feature in northern Australia. However, how such changes affect the soil-atmosphere exchange of nitrous oxide (N2O), nitric oxide (NO) and dinitrogen (N2) is still not well explored. By incubating intact soil cores from four sites (three savanna, one pasture) under controlled soil temperatures (ST) and soil moisture (SM) we investigated the release of the trace gas fluxes of N2O, NO and carbon dioxide (CO2). Furthermore, the release of N2 due to denitrification was measured using the helium gas flow soil core technique. Under dry pre-incubation conditions NO and N2O emissions were very low (<7.0 ± 5.0 μg NO-N m-2 h-1; <0.0 ± 1.4 μg N2O-N m-2 h-1) or in the case of N2O, even a net soil uptake was observed. Substantial NO (max: 306.5 μg N m-2 h-1) and relatively small N2O pulse emissions (max: 5.8 ± 5.0 μg N m-2 h-1) were recorded following soil wetting, but these pulses were short lived, lasting only up to 3 days. The total atmospheric loss of nitrogen was generally dominated by N2 emissions (82.4-99.3% of total N lost), although NO emissions contributed almost 43.2% to the total atmospheric nitrogen loss at 50% SM and 30 °C ST incubation settings (the contribution of N2 at these soil conditions was only 53.2%). N2O emissions were systematically higher for 3 of 12 sample locations, which indicates substantial spatial variability at site level, but on average soils acted as weak N2O sources or even sinks. By using a conservative upscale approach we estimate total annual emissions from savanna soils to average 0.12 kg N ha-1 yr-1 (N2O), 0.68 kg N ha-1 yr-1 (NO) and 6.65 kg N ha-1 yr-1 (N2). The analysis of long-term SM and ST records makes it clear that extreme soil saturation that can lead to high N2O and N2 emissions only occurs a few days per year and thus has little impact on the annual total. The potential contribution of nitrogen released due to pulse events

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

    NASA Astrophysics Data System (ADS)

    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.

  16. EMISSIONS AND COST ESTIMATES FOR GLOBALLY SIGNIFICANT ANTHROPOGENIC COMBUSTION SOURCES OF NOX, N2O, CH4, CO AND CO2

    EPA Science Inventory

    The report discusses the development of emission factors for CO2, CO, CH4, NOx, and N2O for about 80 globally significant combustion sources in seven source categories: utility, industrial, fuel production, transportation, residential, commercial, and kilns/ovens/dryers. ecause o...

  17. 40 CFR Table Jj-7 to Subpart Jj of... - Nitrous Oxide Emission Factors (kg N2O-N/kg Kjdl N)

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Nitrous Oxide Emission Factors (kg N2O-N/kg Kjdl N) JJ Table JJ-7 to Subpart JJ of Part 98 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Manure...

  18. 40 CFR Table I-8 to Subpart I of... - Default Emission Factors (1-UN2O,j) for N2O Utilization (UN2O,j)

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Default Emission Factors (1-UN2O,j) for N2O Utilization (UN2O,j) I Table I-8 to Subpart I of Part 98 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS...

  19. 40 CFR Table I-8 to Subpart I of... - Default Emission Factors (1-UN2O j) for N2O Utilization (UN2O j)

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Default Emission Factors (1-UN2O j) for N2O Utilization (UN2O j) I Table I-8 to Subpart I of Part 98 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS...

  20. 40 CFR Table Jj-7 to Subpart Jj of... - Nitrous Oxide Emission Factors (kg N2O-N/kg Kjdl N)

    Code of Federal Regulations, 2012 CFR

    2012-07-01

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

  1. 40 CFR Table Jj-7 to Subpart Jj of... - Nitrous Oxide Emission Factors (kg N2O-N/kg Kjdl N)

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Nitrous Oxide Emission Factors (kg N2O-N/kg Kjdl N) JJ Table JJ-7 to Subpart JJ of Part 98 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Manure...

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Nitrous Oxide Emission Factors (kg N2O-N/kg Kjdl N) JJ Table JJ-7 to Subpart JJ of Part 98 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Manure...

  3. 40 CFR Table C-2 to Subpart C of... - Default CH4 and N2O Emission Factors for Various Types of Fuel

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Default CH4 and N2O Emission Factors for Various Types of Fuel C Table C-2 to Subpart C of Part 98 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING General Stationary Fuel Combustion Sources Pt. 98, Subpt....

  4. 40 CFR Table Aa-2 to Subpart Aa of... - Kraft Lime Kiln and Calciner Emissions Factors for CH4 and N2O

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Kraft Lime Kiln and Calciner Emissions... Manufacturing Pt. 98, Subpt. AA, Table AA -2 Table AA-2 to Subpart AA of Part 98—Kraft Lime Kiln and Calciner Emissions Factors for CH4 and N2O Fuel Fossil fuel-based emissions factors (kg/mmBtu HHV) Kraft lime...

  5. Estimation and mitigation of N2O emission and nitrate leaching from intensive crop cultivation in the Haean catchment, South Korea.

    PubMed

    Kim, Youngsun; Seo, Youngho; Kraus, David; Klatt, Steffen; Haas, Edwin; Tenhunen, John; Kiese, Ralf

    2015-10-01

    Considering intensive agricultural management practices and environmental conditions, the LandscapeDNDC model was applied for simulation of yields, N2O emission and nitrate leaching from major upland crops and temperate deciduous forest of the Haean catchment, South Korea. Fertilization rates were high (up to 314 kg N ha(-1) year(-1)) and resulted in simulated direct N2O emissions from potato, radish, soybean and cabbage fields of 1.9 and 2.1 kg N ha(-1) year(-1) in 2009 and 2010, respectively. Nitrate leaching was identified as the dominant pathway of N losses in the Haean catchment with mean annual rates of 112.2 and 125.4 kg N ha(-1) year(-1), causing threats to water quality and leading to substantial indirect N2O emissions of 0.84 and 0.94 kg N ha(-1) year(-1) in 2009 and 2010 as estimates by applying the IPCC EF5. Simulated N2O emissions from temperate deciduous forest were low (approx. 0.50 kg N ha(-1) year(-1)) and predicted nitrate leaching rates were even negligible (≤0.01 kg N ha(-1) year(-1)). On catchment scale more than 50% of the total N2O emissions and up to 75% of nitrate leaching originated from fertilized upland fields, only covering 24% of the catchment area. Taking into account area coverage of simulated upland crops and other land uses these numbers agree well with nitrate loads calculated from discharge and concentration measurements at the catchment outlet. The change of current agricultural management practices showed a high potential of reducing N2O emission and nitrate leaching while maintaining current crop yields. Reducing (39%) and splitting N fertilizer application into 3 times was most effective and lead to about 54% and 77% reducing of N2O emission and nitrate leaching from the Haean catchment, the latter potentially contributing to improved water quality in the Soyang River Dam, which is the major source of drinking water for metropolitan residents. PMID:26005748

  6. Greenhouse gas (CO2, CH4, N2O) emissions from soils following afforestation in central China

    NASA Astrophysics Data System (ADS)

    Dou, Xiaolin; Zhou, Wei; Zhang, Quanfa; Cheng, Xiaoli

    2016-02-01

    The effects of afforestation are of great importance for terrestrial carbon sequestration. However, the consequences of afforestation for greenhouse gas (GHG, CO2, CH4 and N2O) fluxes remain poorly quantified. We investigate the temporal variations in CO2, CH4 and N2O fluxes in afforested soils (implementing woodland and shrubland) and the adjacent uncultivated area in the Danjiangkou Reservoir area of central China. We examined the effects of soil factors [e.g. soil temperature, soil moisture, soil pH, soil organic carbon (SOC), soil organic nitrogen (SON)], litter exclusion and vegetation types on GHG fluxes. Our results revealed that afforestation lead to a higher average CO2 flux from soils by 63.96% and a higher N2O flux by 54.53% in the observed year. The peak CO2 and CH4 fluxes from afforested soils occurred in summer, while the peak N2O flux occurred in winter. Afforestation also enhanced CH4 flux from soil with the largest increase by 247.94% in woodland and by 188.18% in shrubland in spring compared with the open area. On average, surface litter exclusion reduced soil CO2 fluxes by 18.84% and N2O fluxes by 27.93% in the woodland. The surface litter exclusion did not significantly affect CH4 flux from the afforested soils. The CO2, CH4 and N2O fluxes from soils were strongly influenced by soil temperature, moisture and SOC content across seasons. The N2O flux was also strongly affected by SON content in our experimental field. Our results suggested that afforestation enhanced GHG fluxes from soils; however, the magnitude of the GHG fluxes should also be considered from various environmental conditions and vegetation types.

  7. The relationship between NH3 emissions from a poultry farm and soil NO and N2O fluxes from a downwind forest

    NASA Astrophysics Data System (ADS)

    Skiba, U.; Dick, J.; Storeton-West, R.; Lopez-Fernandez, S.; Woods, C.; Tang, S.; Vandijk, N.

    2006-08-01

    Intensive livestock farms emit large concentrations of NH3, most of which is deposited very close to the source. The presence of trees enhances the deposition. Rates to downwind forests can exceed 40 kg N ha-1 y-1. The steep gradient in large NH3 concentrations of 34.3±20.4, 47.6±24.9, 21.7±16.8 µg NH3 m3 at the edge of a forest 15, 30 and 45 m downwind of the farm to near background concentrations within 270 m downwind (1.15±0.7 µg NH3 m3) provides an ideal site to study the effect of different rates of atmospheric NH3 concentrations and inferred deposition on biological and chemical processes under similar environmental conditions. We have investigated the effect of different NH3 concentrations and implied deposition rates on the flux of NO and N2O from soil in a mixed woodland downwind of a large poultry farm (160 000 birds) in Scotland, which has been operating for about 40 years. Measurements were carried out for a 6 month period, with hourly NO flux measurements, daily N2O fluxes close to the farm and monthly at all sites, and monthly cumulative wet and dry N deposition. The increased NH3 and NH4+ deposition to the woodland increased emissions of NO and N2O and soil available NH4+ and NO3- concentrations. Average NO and N2O fluxes measured 15, 25 and 45 m downwind of the farm were 111.2±41.1, 123.3±40.7, 38.3±28.8 µg NO-N m-2 h-1 and 9.9±7.5, 34.3±33.3 and 21.2±6.1 µg N2O-N m-2 h-1, respectively. At the background site 270 m downwind the N2O flux was reduced to 1.75±2.1 µg N2O-N m-2 h-1. NO emissions were significantly influenced by seasonal and daily changes in soil temperature and followed a diurnal pattern with maximum emissions approximately 3 h after noon. For N2O no consistent diurnal pattern was observed. Changes in soil moisture content had a less clear effect on the NO and N2O flux. In spite of the large NO and N2O emissions accounting for >3% of the N deposited to the woodland downwind of the farm, extrapolation to the entire British

  8. N2O and CH4 emissions from a Chinese wheat-rice cropping system under different tillage practices during the wheat-growing season

    NASA Astrophysics Data System (ADS)

    Zhang, Y.

    2015-12-01

    The annual wheat (Triticum aestivum L.)-rice (Oryza sativa L.) cropping system is the most important cereal production system in the Yangtze River Valley of China, in which various tillage systems are currently implemented during the wheat-growing season. The emissions of nitrous oxide (N2O) and methane (CH4) from the different tillage systems in this system remain unclear. We conducted a 3-year field experiment in a wheat-rice cropping system in a silt clay loam soil to investigate the effects of the type of tillage employed during the wheat-growing season (no-tillage (NT), reduced tillage (RT) or conventional tillage (CT)) on the emissions of N2O and CH4 using the static chamber method over three annual rotation cycles from the 2008 wheat season to the 2011 rice season. The results revealed that the adoption of an NT system during the wheat-growing season significantly increased CH4 emissions during both the wheat-growing season and the following rice-growing season. Over the three annual rotation cycles studied, the annual N2O emissions from the NT (2.24 kg N2O-N ha-1) and CT (2.01 kg N2O-N ha-1) treatments were similar to each other and significantly higher than those from the RT treatment (1.73 kg N2O-N ha-1); the annual CH4 emissions were significantly higher from the NT (100.1 kg CH4-C ha-1) than the CT (83.7 kg CH4-C ha-1) and RT (73.9 kg CH4-C ha-1) systems. The overall results regarding the net global warming potential associated with annual N2O and CH4 emissions indicate that the conversion of conventional tillage to no-tillage systems during the wheat-growing season would intensify the radiative forcing in wheat-rice cropping systems in China.

  9. The combined effects of nitrification inhibitor and biochar incorporation on yield-scaled N2O emissions from an intensively managed vegetable field in southeastern China

    NASA Astrophysics Data System (ADS)

    Li, B.; Fan, C. H.; Xiong, Z. Q.; Li, Q. L.; Zhang, M.

    2015-03-01

    An experiment was conducted to study the influences of nitrification inhibitor (NI) and biochar incorporation on yield-scaled N2O using the static chamber method and gas chromatography in an intensively managed vegetable field with seven consecutive vegetable crops from 2012 to 2014 in southeastern China. With an equal annual nitrogen (N) application rate (1217 kg N ha-1 yr-1), six treatments under three biochar amendment rates - namely, 0 t ha-1 (C0), 20 t ha-1 (C1) and 40 t ha-1 (C2) - with compound fertilizer (CF) or urea mixed with NI of nitrapyrin as chlorinated pyridine (CP) were studied in these field experiments. The results showed that, although there was no significant influence on soil organic carbon (SOC) content or total nitrogen (TN), nitrapyrin could result in a significant increase in soil pH during the experimental period. Nitrapyrin significantly decreased cumulative N2O emissions by 15.9-32.1% while increasing vegetable yield by 9.8-41.9%. Thus, it also decreased yield-scaled N2O emissions significantly. In addition to the differential responses of the soil pH, biochar amendment significantly increased SOC and TN. Compared with the treatments without biochar addition, the cumulative N2O emissions showed no significant difference in the CF or the CP group treatments but increased slightly (not significantly) by 7.9-18.3% in the CP group treatments. Vegetable yield was enhanced by 7.1-49.5% in the CF group treatments compared with the treatments without biochar amendment, while there was no significant difference in the CP group treatments, and the yield-scaled N2O emissions were thus decreased significantly. Furthermore, treatments involving with nitrapyrin and biochar incorporation slightly increased yield-scaled N2O emissions by 9.4%, on average, compared with CP-C0. Therefore, the application of nitrapyrin could serve as an appropriate practice for increasing vegetable yield and mitigating N2O emissions in intensively managed vegetable fields

  10. Losses of NO and N2O emissions from Venezuelan and other worldwide tropical N-fertilized soils

    NASA Astrophysics Data System (ADS)

    Marquina, Sorena; Donoso, Loreto; Pérez, Tibisay; Gil, Jenie; Sanhueza, Eugenio

    2013-07-01

    fertilization significantly increases N2O and NO soil fluxes to the atmosphere. In spite of the expansion of agricultural activities in tropical managed soils from the developing world, there is little information about the loss of applied nitrogen (LAN) as NO and N2O from these areas. In this work, we determined LAN-N2O and LAN-NO from different crops during the growing season at a sandy soil experimental field and two active farms with loamy and clay soils, respectively. Tillage (T) and no-tillage (NT) farming were separately evaluated. All of the evaluated areas were located in the Venezuela savanna region. A large range of LAN-N2O (0.30-6.1%) and LAN-NO (0.26-2.1%) were recorded, with overall average values of 1.9% and 0.9%, respectively. LAN values were mainly affected by soil texture and rainfall pattern, which affected soil moisture and water-filled pore space. Also, soil management (T and NT) and the chemical composition of the N fertilizer played important roles. The overall average of LAN-N2O is about two times higher than the IPCC default value of 1%; therefore, our results suggest that a higher factor should be considered for cropping systems in tropical savanna regions.

  11. The relationship between ammonia emissions from a poultry farm and soil NO and N2O fluxes from a downwind source

    NASA Astrophysics Data System (ADS)

    Skiba, U.; Dick, J.; Storeton-West, R.; Fernades-Lopez, S.; Wood, C.; Tang, S.; van Dijk, N.

    2005-08-01

    Intensive livestock farms emit large concentrations of NH3, most of which is deposited very close to the source. The presence of trees enhances the deposition. Rates to down wind forests can exceed 40 kg N ha-1. The steep gradient in large NH3 concentration and deposition at the edge of a downwind forest to background concentrations within a few hundred meters provides an ideal site to study the effect of different rates of N deposition on biological and chemical processes under similar environmental conditions. We have investigated the effect of different rates of NH3 deposition (62, 45, 24 and 5 kg NH3-N ha-1 y-1) on the flux of NO and N2O from soil in a mixed woodland downwind of a large poultry farm (160000 birds) in Scotland, which has been operating for about 40 years. Measurements were carried out for a 6 month period, with hourly NO flux measurements, daily N2O fluxes close to the farm and monthly at all sites and monthly cumulative wet and dry N deposition. The increased NH3 and NH4+ deposition to the woodland increased emissions of NO and N2O and soil available NH4+ and NO3- concentrations. Average NO and N2O fluxes measured 15, 25 and 45 m downwind of the farm were 111.2±41.1, 123.3±40.7, 38.3±28.8 µg NO-N m-2 h-1 and 9.9±7.5, 34.3±33.3 and 21.2±6.1 µg NO-N m-2 h-1, respectively. At the background site 270 m downwind the N2O flux was reduced to 1.75±2.1 µg N2O-N m-2 h-1. NO emissions were significantly influenced by seasonal and daily changes in soil temperature and followed a diurnal pattern with maximum emissions approximately 3h after noon. For N2O no consistent diurnal pattern was observed. Changes in soil moisture content had a less clear effect on the NO and N2O flux. On average the NO emissions expressed as a fraction of the elevated N deposited were 7.1% (at 15 m), 6% (at 25 m) and 2.3% (at 45 m) downwind of the farm, whereas for N2O the emissions were only 2.8% (at 15 m), 3% (at 25 m) and 3% (at 45 m) downwind. These emission fractions

  12. Impact of two different types of grassland-to-cropland-conversion on dynamics of soil organic matter mineralization and N2O emission

    NASA Astrophysics Data System (ADS)

    Roth, G.; Flessa, H.; Helfrich, M.; Well, R.

    2012-04-01

    Conversion of grassland to arable land often causes a decrease of soil organic matter stocks and it increases nitrate leaching and the emission of the greenhouse gases CO2 and N2O. Conversion methods which minimize the mechanical impact on the surface soil may reduce mineralization rates and greenhouse gas emissions. We determined the effect of two different types of grassland to maize conversion (a) plowing of the sward followed by seeding of maize and (b) chemical killing of the sward by glyphosate followed by direct seed of maize) on the mineralization of grassland derived organic matter, the release of nitrate and the emission of N2O. The field experiment was carried out at the research station Kleve which is located in North Rhine-Westphalia, Germany. A four times replicated plot experiment with the following treatments was set up in April 2010: (i) mechanical conversion of grassland to maize (ii) chemical conversion grassland to maize and (iii) continuous grassland as reference. Nitrogen fertilization was 137 kg N ha-1 for maize and 250 kg N ha-1 for grassland. Soil respiration and emission of N2O were measured weekly for one year using manual closed chambers and gas chromatography. Emission of CO2 from mineralization of grassland-derived organic matter was determined from the δ13C signature of soil respiration. Soil respiration was mainly fueled by mineralization of grassland-derived organic carbon. There was no effect of the type of grassland conversion on total mineralization of organic matter originating from grassland. Both grassland to maize conversion treatments exhibited very high soil nitrate concentrations one year after grassland conversion (about 250 kg NO3-N in 0 - 90 cm). Total N2O emission decreased in the order chemical conversion of grassland (25.5) > mechanical conversion of grassland (20.1) > permanent grassland (10.8). Emissions were highest after harvest of maize when soil moisture increased. The results show that both types of grassland

  13. [Characteristics of N2, N2O, NO, CO2 and CH4 Emissions in Anaerobic Condition from Sandy Loam Paddy Soil].

    PubMed

    Cao, Na; Wang, Rui; Liao, Ting-ting; Chen, Nuo; Zheng, Xun-hua; Yao, Zhi-sheng; Zhang, Hai; Butterbach-Bahl, Klaus

    2015-09-01

    Understanding the characteristics of the production of nitrogen gases (N2, N2O and NO), CO2 and CH4 in anaerobic paddy soils is not only a prerequisite for an improved mechanistic understanding of key microbial processes involved in the production of atmospheric greenhouse gases (GHG), but might also provide the basis for designing greenhouse gas mitigation strategies. Moreover, quantifying the composition fractions of denitrification gaseous products is of key importance for improving parameterization schemes of microbial processes in process-oriented models which are increasingly used for assessing soil GHG emissions at site and national scales. In our experiments we investigated two sandy loam soils from two paddy fields. The initial concentrations of soil nitrate and dissolved organic carbon (DOC) were set at approximately 50 mg.kg-1 and mg.kg-1, respectively, by adding a mixture solution of KNO3 and glucose. The emissions of N2, N2O NO, CO2 and CH4, as well as concentrations of carbon and nitrogen substrates for each soil sample were measured simultaneously, using a gas-flow-soil-core technique and a paralleling substrate monitoring system. The results showed that the accumulative emissions of N2, N2O and NO of the two soil samples for the entire incubation period were 6 - 8, 20, and 15 - 18 mg.kg-1, respectively. By measuring the cumulative emissions of denitrification gases (N, = N2 + N2O + NO) we were able to explain 95% to 98% of observed changes in s1ifr nilrate concentrations. The mass fractions of N2, N2O and NO emissions to Nt were approximately 15% -19%, 47% -49%, and 34% -36%, respectively. Thus, in our experiments N2O and NO were the main products of denitrification for the entire incubation period. However, as the temporal courses of hourly or daily production of the denitrification gases showed, NO production dominated and peaked firstly, and then N2O, before finally N2 became the dominant product. Our results show the high temporal dynamic of

  14. In-Situ Denitrification and N2O Emission from Natural and Semi-natural Land Use Types in two UK Catchments

    NASA Astrophysics Data System (ADS)

    Sgouridis, F.; Ullah, S.

    2014-12-01

    Whilst data and understanding of the controls of denitrification process and the subsequent emission of N2O at microbial and plot scale exist, quantification of in situ annual denitrification rates at catchment scales is scarce due to methodological constraints in measuring in situ denitrification in large temporal and spatial scales. In situ denitrification (DNT) was measured monthly (April 2013 - October 2014) in organic (peat bog, heathland, acid grassland), forest (mixed and deciduous), and grassland (improved and semi-improved) land use types in the Ribble-Wyre and Conwy River catchments in the UK. A static chamber technique according to the 15N-Gas Flux method1 was employed for quantifying the fluxes of 15N-N2 and 15N-N2O gases after labelling the soil with 98 at% K15NO3- at tracer level amounts (10% of the ambient nitrate concentration) and sampling the chamber headspace at 0, 1, 2 and 20 hour intervals. The DNT rates ranged between 0 and 2.3 mg N m-2 h-1 and were significantly influenced by land use type (p<0.05). The annual denitrification rate of organic and forest soils (4 kg N ha-1 y-1) was 3 and 6 times less than that of semi-improved (12 kg N ha-1 y-1) and improved (23 kg N ha-1 y-1) grassland soils, respectively. The N2O emission, due to denitrification, followed a similar trend with lower fluxes from organic and higher from improved grassland soils (range: 0 - 0.04 mg N m-2 h-1), whilst the N2O:N2 ratio ranged between 0.2 and 4%. The relative contribution of denitrification to net N2O flux varied temporally and across the different land use types and ranged from 0.2 to 75%. The 15N-Gas Flux method can be successfully applied in a variety of land use types for relatively high temporal and spatial resolution measurement of in situ denitrification and the simultaneous quantification of N2 and N2O fluxes due to denitrification. Therefore the ratio of N2O:N2 and also the source apportionment for N2O can be estimated more accurately. The results suggested

  15. Effects of nitrogen on the ecosystem respiration, CH4 and N2O emissions to the atmosphere from the freshwater marshes in northeast China

    NASA Astrophysics Data System (ADS)

    Zhang, Lihua; Song, Changchun; Zheng, Xunhua; Wang, Dexuan; Wang, Yiyong

    2007-04-01

    Freshwater marshes could be a source of greenhouse gases emission because they contain large amounts of soil carbon and nitrogen. These emissions are strongly influenced by exogenous nitrogen. We investigate the effects of exogenous nitrogen on ecosystem respiration (CO2), CH4 and N2O emissions from freshwater marshes in situ in the Sanjiang Plain Northeast of China during the growing seasons of 2004 and 2005, using a field fertilizer experiment and the static opaque chamber/GC techniques. The results show that there were no significant differences in patterns of seasonal variations of CO2 and CH4 among the fertilizer and non-fertilizer treatments, but the seasonal patterns of N2O emission were significantly influenced by the exogenous nitrogen. Seasonal averages of the CO2 flux from non-fertilizer and fertilizer were 987.74 and 1,344.35 mg m -2 h -1, respectively, in 2004, and 898.59 and 2,154.17 mg m -2 h -1, respectively, in 2005. And the CH4 from the control and fertilizer treatments were 6.05 and 13.56 mg m -2 h -1 and 0.72 and 1.88 mg m -2 h -1, respectively, in 2004 and 2005. The difference of N2O flux between the fertilizer and non-fertilizer treatments is also significant either in 2004 and 2005. On the time scale of 20-, 100-, and 500-year periods, the integrated global warming potential (GWP) of CO2 +CH4 +N2O released during the two growing seasons for the treatment of fertilizer was 97, 94 and 89%, respectively, higher than that for the control, which suggested that the nitrogen fertilizer can enhance the GWP of the CH4 and N2O either in long time or short time scale.

  16. Effects of Winter Cover Crops Straws Incorporation on CH4 and N2O Emission from Double-Cropping Paddy Fields in Southern China

    PubMed Central

    Tang, Hai-Ming; Xiao, Xiao-Ping; Tang, Wen-Guang; Wang, Ke; Sun, Ji-Min; Li, Wei-Yan; Yang, Guang-Li

    2014-01-01

    Residue management in cropping systems is believed to improve soil quality. However, the effects of residue management on methane (CH4) and nitrous oxide (N2O) emissions from paddy field in Southern China have not been well researched. The emissions of CH4 and N2O were investigated in double cropping rice (Oryza sativa L.) systems with straw returning of different winter cover crops by using the static chamber-gas chromatography technique. A randomized block experiment with three replications was established in 2004 in Hunan Province, China, including rice–rice–ryegrass (Lolium multiflorum L.) (Ry-R-R), rice–rice–Chinese milk vetch (Astragalus sinicus L.) (Mv-R-R) and rice–rice with winter fallow (Fa-R-R). The results showed that straw returning of winter crops significantly increased the CH4 emission during both rice growing seasons when compared with Fa-R-R. Ry-R-R plots had the largest CH4 emissions during the early rice growing season with 14.235 and 15.906 g m−2 in 2012 and 2013, respectively, when Ry-R-R plots had the largest CH4 emission during the later rice growing season with 35.673 and 38.606 g m−2 in 2012 and 2013, respectively. The Ry-R-R and Mv-R-R also had larger N2O emissions than Fa-R-R in both rice seasons. When compared to Fa-R-R, total N2O emissions in the early rice growing season were increased by 0.05 g m−2 in Ry-R-R and 0.063 g m−2 in Mv-R-R in 2012, and by 0.058 g m−2 in Ry-R-R and 0.068 g m−2 in Mv-R-R in 2013, respectively. Similar result were obtained in the late rice growing season, and the total N2O emissions were increased by 0.104 g m−2 in Ry-R-R and 0.073 g m−2 in Mv-R-R in 2012, and by 0.108 g m−2 in Ry-R-R and 0.076 g m−2 in Mv-R-R in 2013, respectively. The global warming potentials (GWPs) from paddy fields were ranked as Ry-R-R>Mv-R-R>Fa-R-R. As a result, straw returning of winter cover crops has significant effects on increase of CH4 and N2O emission from paddy field in double cropping rice system

  17. N2O FIELD STUDY

    EPA Science Inventory

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

  18. Gaseous Nitrogen Losses from Tropical Savanna Soils of Northern Australia: Dynamics, Controls and Magnitude of N2O, NO, and N2 emissions

    NASA Astrophysics Data System (ADS)

    Werner, C.; Hickler, T.; Hutley, L. B.; Butterbach-Bahl, K.

    2014-12-01

    Tropical savanna covers a large fraction of the global land area and thus may have a substantial effect on the global soil-atmosphere exchange of nitrogen. The pronounced seasonality of hygric conditions in this ecosystem affects strongly microbial process rates in the soil. As these microbial processes control the uptake, production, and release of nitrogen compounds, it is thought that this seasonality finally leads to strong temporal dynamics and varying magnitudes of gaseous losses to the atmosphere. However, given their areal extent and in contrast to other ecosystems, still few in-situ or laboratory studies exist that assess the soil-atmosphere exchange of nitrogen. We present laboratory incubation results from intact soil cores obtained from a natural savanna site in Northern Australia, where N2O, NO, and N2 emissions under controlled environmental conditions were investigated. Furthermore, in-situ measurements of high temporal resolution at this site recorded with automated static and dynamic chamber systems are discussed (N2O, NO). This data is then used to assess the performance of a process-based biogeochemical model (LandscapeDNDC), and the potential magnitude and dynamics of components of the site-scale nitrogen cycle where no measurements exist (biological nitrogen fixation and nitrate leaching). Our incubation results show that severe nutrient limitation of the soil only allows for very low N2O emissions (0.12 kg N ha-1 yr-1) and even a periodic N2O uptake. Annual NO emissions were estimated at 0.68 kg N ha-1 yr-1, while the release of inert nitrogen (N2) was estimated at 6.75 kg N ha-1 yr-1 (data excl. contribution by pulse emissions). We observed only minor N2O pulse emissions after watering the soil cores and initial rain events of the dry to wet season transition in-situ, but short-lived NO pulse emissions were substantial. Interestingly, some cores exhibited a very different N2O emission potential, indicating a substantial spatial variability of

  19. Emissions of CH4 and N2O over the United States and Canada based on a receptor-oriented modeling framework and COBRA-NA atmospheric observations

    NASA Astrophysics Data System (ADS)

    Kort, Eric A.; Eluszkiewicz, Janusz; Stephens, Britton B.; Miller, John B.; Gerbig, Christoph; Nehrkorn, Thomas; Daube, Bruce C.; Kaplan, Jed O.; Houweling, Sander; Wofsy, Steven C.

    2008-09-01

    We present top-down emission constraints for two non-CO2 greenhouse gases in large areas of the U.S. and southern Canada during early summer. Collocated airborne measurements of methane and nitrous oxide acquired during the COBRA-NA campaign in May-June 2003, analyzed using a receptor-oriented Lagrangian particle dispersion model, provide robust validation of independent bottom-up emission estimates from the EDGAR and GEIA inventories. We find that the EDGAR CH4 emission rates are slightly low by a factor of 1.08 +/- 0.15 (2σ), while both EDGAR and GEIA N2O emissions are significantly too low, by factors of 2.62 +/- 0.50 and 3.05 +/- 0.61, respectively, for this region. Potential footprint bias may expand the statistically retrieved uncertainties. Seasonality of agricultural N2O emissions may help explain the discrepancy. Total anthropogenic U.S. and Canadian emissions would be 49 Tg CH4 and 4.3 Tg N2O annually, if these inventory scaling factors applied to all of North America.

  20. Influence of bulking agents on CH4, N2O, and NH3 emissions during rapid composting of pig manure from the Chinese Ganqinfen system*

    PubMed Central

    Sun, Xiang-ping; Lu, Peng; Jiang, Tao; Schuchardt, Frank; Li, Guo-xue

    2014-01-01

    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, especially 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 the corn stalks and spent mushroom compost. However, there were no significant differences among the three runs for total carbon loss. All treatments were matured after 30 d. PMID:24711356

  1. Historical and future land use effects on N2O and NO emissions using an ensemble modeling approach: Costa Rica's Caribbean lowlands as an example

    USGS Publications Warehouse

    Reiners, William A.; Liu, S.; Gerow, K.G.; Keller, M.; Schimel, D.S.

    2002-01-01

    [1] The humid tropical zone is a major source area for N2O and NO emissions to the atmosphere. Local emission rates vary widely with local conditions, particularly land use practices which swiftly change with expanding settlement and changing market conditions. The combination of wide variation in emission rates and rapidly changing land use make regional estimation and future prediction of biogenic trace gas emission particularly difficult. This study estimates contemporary, historical, and future N2O and NO emissions from 0.5 million ha of northeastern Costa Rica, a well-documented region in the wet tropics undergoing rapid agricultural development. Estimates were derived by linking spatially distributed environmental data with an ecosystem simulation model in an ensemble estimation approach that incorporates the variance and covariance of spatially distributed driving variables. Results include measures of variance for regional emissions. The formation and aging of pastures from forest provided most of the past temporal change in N2O and NO flux in this region; future changes will be controlled by the degree of nitrogen fertilizer application and extent of intensively managed croplands.

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

    NASA Astrophysics Data System (ADS)

    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

  3. Soil and fertilizer type effects on short-term N2 and N2O emissions: Results of a helium-oxygen incubation study

    NASA Astrophysics Data System (ADS)

    Hagemann, Ulrike; Andres, Monique; Augustin, Jürgen

    2015-04-01

    Emitted N gas species from agricultural fields are highly relevant in terms of environmental and climate protection and mainly result from numerous simultaneously occurring production and consumption processes, which are influenced by a range of proximal (e.g. nutrient and oxygen availability) and distal factors (e.g. soil conditions, climate and management). Fertilization generally influences the rate of denitrification through increased C and N availability in the soil. But, compared to unfermented organic fertilizers, this effect is more pronounced for fermented residues (FR) due to higher concentrations of NH4+, Nt and labile organic C. Thus, FR likely serve as an additional energy source for denitrifying bacteria, potentially resulting in temporally increased denitrification rates. However, field studies of simultaneous N2 and N2O emissions following fertilization with FR are still lacking, but are required to improve our understanding of the combined effects of relevant factors on the resulting N2 : N2O ratios. We will present results of an incubation experiment conducted to quantify the effects of i) 2 N fertilizer types (fermentation residue, FR and granular calcium ammonium nitrate, CAN) and ii) 5 soil types (ranging from slightly loamy sand to very clayey silt) on short-term emissions of N2 and N2O as well as N2 : N2O ratios. Immediately after fertilizer application and incorporation in spring 2012, five intact soil cores per treatment were randomly taken from each of 5 study sites in Germany. Simultaneous measurements of N2O and N2 fluxes were conducted in special gas-tight incubation vessels inside a climate box at 10°C using the helium-oxygen incubation method of Butterbach-Bahl et al. (2002), classified as a flow-through steady-state system according to Livingston and Hutchinson (1995). Across all sites, FR samples showed both significantly higher absolute and relative (to fertilizer N input) N2O efflux and significantly higher average absolute and

  4. The impact of corn stover removal on N2O emission and soil respiration: An investigation with automated chambers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn stover removal, whether for silage, bedding, or bioenergy production, could have a variety of environmental consequences through its effect on soil processes, particularly N2O production and soil respiration. Because these effects may be episodic in nature, weekly snapshots with static chambers...

  5. Effects of struvite formation and nitratation promotion on nitrogenous emissions such as NH3, N2O and NO during swine manure composting.

    PubMed

    Fukumoto, Yasuyuki; Suzuki, Kazuyoshi; Kuroda, Kazutaka; Waki, Miyoko; Yasuda, Tomoko

    2011-01-01

    To reduce nitrogenous emissions from composting, two different countermeasures were applied simultaneously in swine manure composting. One was forming struvite by adding Mg and P at the start of composting, and the other was to promote nitratation (nitrite being oxidized nitrate) by adding nitrite-oxidizing bacteria after the thermophilic phase of composting. In the laboratory- and mid-scale composting experiments, 25-43% of NH3, 52-80% of N2O and 96-99% of NO emissions were reduced. From the nitrogen balance, it was revealed that the struvite formation reduced not only NH3, but also other nitrogenous emissions except N2O. The amount of total nitrogen losses was reduced by 60% by the two combined countermeasures, against 51% by the struvite formation alone. However, the nitratation promotion dissolved struvite crystals due to the pH decline, diminishing the effect of struvite as a slow-release fertilizer. PMID:20952186

  6. Short-term emissions of CO2 and N2O in response to periodic flood irrigation with waste water in the Mezquital Valley of Mexico

    NASA Astrophysics Data System (ADS)

    González-Méndez, B.; Webster, R.; Fiedler, S.; Loza-Reyes, E.; Hernández, J. M.; Ruíz-Suárez, L. G.; Siebe, C.

    2015-01-01

    Irrigation with waste water adds labile carbon and nitrogen compounds to the soil, and when applied by flooding it rapidly changes the soil's atmosphere and redox potential. In the Mezquital Valley more than 90 000 ha is irrigated with waste water from Mexico City, and enhanced emissions of CO2 and N2O follow each flooding. We measured the emissions of these two gases from a field irrigated periodically with waste water and under three crops, namely alfalfa, rye-grass and maize, using static chambers for 21 months. We also measured emissions from a field growing rain-fed maize before and shortly after two rain events. The data from repeated measurements from the same chambers are correlated in time, and so we modelled the ante-dependence and fitted the models by residual maximum likelihood (REML). The emissions of both CO2 and N2O increased rapidly in response to flood irrigation with peaks up to 448 mg C m-2 hour-1 for CO2 and 2.98 mg N m-2 hour-1 for N2O under maize. Emissions peaked in particular irrigation events either as the infiltrating water replaced the gas from air-filled pores or several days after irrigation as excess nitrogen and fresh sources of carbon were mineralized. Processes operating during the few days during and immediately after irrigation seem to determine the dynamics of gaseous production in this agricultural ecosystem.

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

    PubMed

    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 (P<0.05) in fallow than in wheat subplots, and NT reduced N2O emissions (P<0.05) compared with MT and CT. Taking into account the water filled pore space (WFPS), both nitrification and denitrification could have occurred during the experimental period. Denitrification capacity in March was similar in all tillage 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. PMID:25459752

  8. Disaggregated N2O emission factors in China based on cropping parameters create a robust approach to the IPCC Tier 2 methodology

    NASA Astrophysics Data System (ADS)

    Shepherd, Anita; Yan, Xiaoyuan; Nayak, Dali; Newbold, Jamie; Moran, Dominic; Dhanoa, Mewa Singh; Goulding, Keith; Smith, Pete; Cardenas, Laura M.

    2015-12-01

    China accounts for a third of global nitrogen fertilizer consumption. Under an International Panel on Climate Change (IPCC) Tier 2 assessment, emission factors (EFs) are developed for the major crop types using country-specific data. IPCC advises a separate calculation for the direct nitrous oxide (N2O) emissions of rice cultivation from that of cropland and the consideration of the water regime used for irrigation. In this paper we combine these requirements in two independent analyses, using different data quality acceptance thresholds, to determine the influential parameters on emissions with which to disaggregate and create N2O EFs. Across China, the N2O EF for lowland horticulture was slightly higher (between 0.74% and 1.26% of fertilizer applied) than that for upland crops (values ranging between 0.40% and 1.54%), and significantly higher than for rice (values ranging between 0.29% and 0.66% on temporarily drained soils, and between 0.15% and 0.37% on un-drained soils). Higher EFs for rice were associated with longer periods of drained soil and the use of compound fertilizer; lower emissions were associated with the use of urea or acid soils. Higher EFs for upland crops were associated with clay soil, compound fertilizer or maize crops; lower EFs were associated with sandy soil and the use of urea. Variation in emissions for lowland vegetable crops was closely associated with crop type. The two independent analyses in this study produced consistent disaggregated N2O EFs for rice and mixed crops, showing that the use of influential cropping parameters can produce robust EFs for China.

  9. Disaggregated N2O emission factors in China based on cropping parameters create a robust approach to the IPCC Tier 2 methodology

    PubMed Central

    Shepherd, Anita; Yan, Xiaoyuan; Nayak, Dali; Newbold, Jamie; Moran, Dominic; Dhanoa, Mewa Singh; Goulding, Keith; Smith, Pete; Cardenas, Laura M.

    2015-01-01

    China accounts for a third of global nitrogen fertilizer consumption. Under an International Panel on Climate Change (IPCC) Tier 2 assessment, emission factors (EFs) are developed for the major crop types using country-specific data. IPCC advises a separate calculation for the direct nitrous oxide (N2O) emissions of rice cultivation from that of cropland and the consideration of the water regime used for irrigation. In this paper we combine these requirements in two independent analyses, using different data quality acceptance thresholds, to determine the influential parameters on emissions with which to disaggregate and create N2O EFs. Across China, the N2O EF for lowland horticulture was slightly higher (between 0.74% and 1.26% of fertilizer applied) than that for upland crops (values ranging between 0.40% and 1.54%), and significantly higher than for rice (values ranging between 0.29% and 0.66% on temporarily drained soils, and between 0.15% and 0.37% on un-drained soils). Higher EFs for rice were associated with longer periods of drained soil and the use of compound fertilizer; lower emissions were associated with the use of urea or acid soils. Higher EFs for upland crops were associated with clay soil, compound fertilizer or maize crops; lower EFs were associated with sandy soil and the use of urea. Variation in emissions for lowland vegetable crops was closely associated with crop type. The two independent analyses in this study produced consistent disaggregated N2O EFs for rice and mixed crops, showing that the use of influential cropping parameters can produce robust EFs for China. PMID:26865831

  10. A novel 15N tracer approach for the quantification of N2 and N2O emissions from soil incubations in a completely automated laboratory set up

    NASA Astrophysics Data System (ADS)

    Scheer, Clemens; Dannenmann, Michael; Meier, Rudolf

    2015-04-01

    The microbial mediated production of nitrous oxide (N2O) and its reduction to dinitrogen (N2) via denitrification represents a loss of nitrogen (N) from fertilised agro-ecosystems to the atmosphere. Although denitrification has received great interest by biogeochemists in the last decades, the magnitude of N2lossesand related N2:N2O ratios from soils still are largely unknown due to methodical constraints. We present a novel 15N tracer approach, based on a previous developed tracer method to study denitrification in pure bacterial cultures which was modified for the use on soil incubations in a completely automated laboratory set up. The method uses a background air in the incubation vessels that is replaced with a helium-oxygen gas mixture with a 50-fold reduced N2 background (2 % v/v). This method allows for a direct and sensitive quantification of the N2 and N2O emissions from the soil with isotope-ratio mass spectrometry after 15N labelling of denitrification N substrates and minimises the sensitivity to the intrusion of atmospheric N2 at the same time. The incubation set up was used to determine the influence of different soil moisture levels on N2 and N2O emissions from a sub-tropical pasture soil in Queensland/Australia. The soil was labelled with an equivalent of 50 μg-N per gram dry soil by broadcast application of KNO3solution (4 at.% 15N) and incubated for 3 days at 80% and 100% water filled pore space (WFPS), respectively. The headspace of the incubation vessel was sampled automatically over 12hrs each day and 3 samples (0, 6, and 12 hrs after incubation start) of headspace gas analysed for N2 and N2O with an isotope-ratio mass spectrometer (DELTA V Plus, Thermo Fisher Scientific, Bremen, Germany(. In addition, the soil was analysed for 15N NO3- and NH4+ using the 15N diffusion method, which enabled us to obtain a complete N balance. The method proved to be highly sensitive for N2 and N2O emissions detecting N2O emissions ranging from 20 to 627 μN kg

  11. Upscaling methane emission hotspots in boreal peatlands

    NASA Astrophysics Data System (ADS)

    Cresto Aleina, Fabio; Runkle, Benjamin R. K.; Brücher, Tim; Kleinen, Thomas; Brovkin, Victor

    2016-03-01

    Upscaling the properties and effects of small-scale surface heterogeneities to larger scales is a challenging issue in land surface modeling. We developed a novel approach to upscale local methane emissions in a boreal peatland from the micro-topographic scale to the landscape scale. We based this new parameterization on the analysis of the water table pattern generated by the Hummock-Hollow model, a micro-topography resolving model for peatland hydrology. We introduce this parameterization of methane hotspots in a global model-like version of the Hummock-Hollow model that underestimates methane emissions. We tested the robustness of the parameterization by simulating methane emissions for the next century, forcing the model with three different RCP scenarios. The Hotspot parameterization, despite being calibrated for the 1976-2005 climatology, mimics the output of the micro-topography resolving model for all the simulated scenarios. The new approach bridges the scale gap of methane emissions between this version of the model and the configuration explicitly resolving micro-topography.

  12. Upscaling methane emission hotspots in boreal peatlands

    NASA Astrophysics Data System (ADS)

    Cresto Aleina, F.; Runkle, B. R. K.; Brücher, T.; Kleinen, T.; Brovkin, V.

    2015-10-01

    Upscaling the properties and the effects of small-scale surface heterogeneities to larger scales is a challenging issue in land surface modeling. We developed a novel approach to upscale local methane emissions in a boreal peatland from the micro-topographic scale to the landscape-scale. We based this new parameterization on the analysis of the water table pattern generated by the Hummock-Hollow model, a micro-topography resolving model for peatland hydrology. We introduce this parameterization of methane hotspots in a global model-like version of the Hummock-Hollow model, that underestimates methane emissions. We tested the robustness of the parameterization by simulating methane emissions for the next century forcing the model with three different RCP scenarios. The Hotspot parameterization, despite being calibrated for the 1976-2005 climatology, mimics the output of the micro-topography resolving model for all the simulated scenarios. The new approach bridges the scale gap of methane emissions between this version of the model and the configuration explicitly resolving micro-topography.

  13. The effect of renovation of long-term temperate grassland on N2O emissions and N leaching from contrasting soils.

    PubMed

    Krol, D J; Jones, M B; Williams, M; Richards, K G; Bourdin, F; Lanigan, G J

    2016-08-01

    Renovation of long-term grassland is associated with a peak in soil organic N mineralisation which, coupled with diminished plant N uptake can lead to large gaseous and leaching N losses. This study reports on the effect of ploughing and subsequent N fertilisation on the N2O emissions and DON/NO3(-) leaching, and evaluates the impact of ploughing technique on the magnitude and profile of N losses. This study was carried out on isolated grassland lysimeters of three Irish soils representing contrasting drainage properties (well-drained Clonakilty, moderately-drained Elton and poorly-drained Rathangan). Lysimeters were manually ploughed simulating conventional (CT) and minimum tillage (MT) as two treatments. Renovation of grassland increased N2O flux to a maximum of 0.9kgN2O-Nha(-1) from poorly-drained soil over four days after treatment. Although there was no difference between CT and MT in the post-ploughing period, the treatment influenced subsequent N2O after fertiliser applications. Fertilisation remained the major driver of N losses therefore reducing fertilisation rate post-planting to account for N mineralised through grassland renovation could reduce the losses in medium to longer term. Leaching was a significant loss pathway, with the cumulative drainage volume and N leached highly influenced by soil type. Overall, the total N losses (N2O+N leached) were lowest from poorly and moderately draining soil and highest for the well draining soil, reflecting the dominance of leaching on total N losses and the paramount importance of soil properties. PMID:27101460

  14. Effect of measurement network densities and stratification on the uncertainty of implied emission factors for national N2O budgets from agricultural mineral soils

    NASA Astrophysics Data System (ADS)

    Dechow, Rene; Gebbert, Soeren

    2015-04-01

    Among other GHG sources that are reported under the United Nations Framework Convention on Climate Change (UNFCCC) national budgets of nitrous oxide emissions from agricultural soils are often characterized by the highest estimation uncertainties within the sectors "agriculture" and "land use and land use change". The majority of recent national emission inventories in Europe are based on Tier 1 approaches. Nitrous oxide emissions from mineral soils are highly influenced by anthropogenic and environmental conditions like soil properties and climate. Specification of those controlling factors on a national to regional scale can highly influence the spatial emission pattern and might cause systematic errors when using Tier 1 emission factors. Regionally stratified emission factors reflecting conditions that determine the N2O flux rates from agricultural soils could significantly improve the accuracy of national nitrous oxide emission inventories (Tier 2). If these stratified emission factors are based on measurement networks the density and stratification of measurement networks with respect to spatial variability of soil properties and climate is an important driver of emission factor uncertainty. In the last two decades, intensive effort has been spend on the experimentally determination of nitrous oxide emissions at plot scale and related drivers resulting in numerous published data sets that were collected and analyzed within meta-studies and European and international projects. We give an overview on recently available data on direct nitrous oxide emissions on agricultural land in Europe. Mixed linear models are trained on these data sets. These models estimate N2O emissions in response to management, meteorological data and soil properties. Based on the developed mixed linear models the effect of N2O measurement network density and stratification on bias and uncertainty of national implied emission factors from agricultural soils are quantified by Monte Carlo

  15. Upscaling methane emission hotspots in boreal peatlands

    NASA Astrophysics Data System (ADS)

    Cresto Aleina, Fabio; Runkle, Benjamin R. K.; Bruecher, Tim; Kleinen, Thomas; Brovkin, Victor

    2016-04-01

    Small-scale surface heterogeneities can influence land-atmosphere fluxes and therefore carbon, water and energy budgets on a larger scale. This effect is of particular relevance for high-latitude ecosystems, because of the great amount of carbon stored in their soils. Upscaling such small-scale surface heterogeneities and their effects to larger scales is a challenging issue in land surface modeling. We developed a novel approach to upscale local methane emissions in a boreal peatland from the micro-topographic scale to the landscape-scale. We based this parameterization on the analysis of the water table pattern generated by the Hummock-Hollow model (Cresto Aleina et al., 2015), a micro-topography resolving model for peatland hydrology and methane emissions. By computing the water table at the micro-topographic scale, the Hummock-Hollow model is able to describe the effects of micro-topography on hydrology and methane emissions in a typical boreal peatland. We introduce the new parameterization of methane hotspots in a global model-like version of the Hummock-Hollow model. This latter version underestimates methane emissions because of the lack of representation of micro-topographic controls on peatland hydrology. We tested the robustness of the parameterization by simulating methane emissions for the present day and for the next century, forcing the model with three different RCP scenarios. The Hotspot parameterization, despite being calibrated for the 1976-2005 climatology, mimics the output of the micro-topography resolving model for all the simulated scenarios. The new approach bridges the scale gap of methane emissions between this version of the model and the configuration explicitly resolving micro-topography.

  16. Upscaling NZ-DNDC using a regression based meta-model to estimate direct N2O emissions from New Zealand grazed pastures.

    PubMed

    Giltrap, Donna L; Ausseil, Anne-Gaëlle E

    2016-01-01

    The availability of detailed input data frequently limits the application of process-based models at large scale. In this study, we produced simplified meta-models of the simulated nitrous oxide (N2O) emission factors (EF) using NZ-DNDC. Monte Carlo simulations were performed and the results investigated using multiple regression analysis to produce simplified meta-models of EF. These meta-models were then used to estimate direct N2O emissions from grazed pastures in New Zealand. New Zealand EF maps were generated using the meta-models with data from national scale soil maps. Direct emissions of N2O from grazed pasture were calculated by multiplying the EF map with a nitrogen (N) input map. Three meta-models were considered. Model 1 included only the soil organic carbon in the top 30cm (SOC30), Model 2 also included a clay content factor, and Model 3 added the interaction between SOC30 and clay. The median annual national direct N2O emissions from grazed pastures estimated using each model (assuming model errors were purely random) were: 9.6GgN (Model 1), 13.6GgN (Model 2), and 11.9GgN (Model 3). These values corresponded to an average EF of 0.53%, 0.75% and 0.63% respectively, while the corresponding average EF using New Zealand national inventory values was 0.67%. If the model error can be assumed to be independent for each pixel then the 95% confidence interval for the N2O emissions was of the order of ±0.4-0.7%, which is much lower than existing methods. However, spatial correlations in the model errors could invalidate this assumption. Under the extreme assumption that the model error for each pixel was identical the 95% confidence interval was approximately ±100-200%. Therefore further work is needed to assess the degree of spatial correlation in the model errors. PMID:26363395

  17. North American terrestrial CO2 uptake largely offset by CH4 and N2O emissions: toward a full accounting of the greenhouse gas budget

    DOE PAGESBeta

    Tian, Hanqin; Chen, Guangsheng; Lu, Chaoqun; Xu, Xiaofeng; Hayes, Daniel J.; Ren, Wei; Pan, Shufen; Huntzinger, Deborah N.; Wofsy, Steven C.

    2014-03-14

    The terrestrial ecosystems of North America have been identified as a sink of atmospheric CO2 though there is no consensus on the magnitude. However, the emissions of non-CO2 greenhouse gases (CH4 and N2O) may offset or even overturn the climate cooling effect induced by the CO2 sink. Using a coupled biogeochemical model, in this study, we have estimated the combined global warming potentials (GWP) of CO2, CH4 and N2O fluxes in North American terrestrial ecosystems and quantified the relative contributions of environmental factors to the GWP changes during 1979–2010. The uncertainty range for contemporary global warming potential has been quantifiedmore » by synthesizing the existing estimates from inventory, forward modeling, and inverse modeling approaches. Our “best estimate” of net GWP for CO2, CH4 and N2O fluxes was₋0.50 ± 0.27 Pg CO2 eq/year (1 Pg=1015 g) in North American terrestrial ecosystems during 2001–2010. The emissions of CH4 and N2O from terrestrial ecosystems had offset about two thirds (73% ± 14%) of the land CO2 sink in the North American continent, showing large differences across the three countries, with offset ratios of 57% ± 8% in US, 83% ± 17 % in Canada and 329% ± 119 % in Mexico. Climate change and elevated tropospheric ozone concentration have contributed the most to GWP increase, while elevated atmospheric CO2 concentration have contributed the most to GWP reduction. Extreme drought events over certain periods could result in a positive GWP. By integrating the existing estimates, we have found a wide range of uncertainty for the combined GWP. In conclusion, from both climate change science and policy perspectives, it is necessary to integrate ground and satellite observations with models for a more accurate accounting of these three greenhouse gases in North America.« less

  18. Sub-arctic Wetland Greenhouse Gases (CO2, CH4 & N2O) Emissions are Driven by Interactions of Environmental Controls and Herbivore Grazers

    NASA Astrophysics Data System (ADS)

    Kelsey, K.; Leffler, A. J.; Beard, K. H.; Choi, R. T.; Welker, J. M.

    2015-12-01

    Climate change is increasing temperatures, altering precipitation regimes and causing earlier growing seasons, particularly at northern latitudes. Such changes in local environmental conditions have the potential to affect biogeochemical cycling including the exchange of greenhouses gases between the atmosphere and the terrestrial biosphere. In addition to the effects of these environmental controls, animals such as migratory geese also influence biogeochemical cycles through grazing, trampling and delivering nutrient-rich fecal matter. In this work we aimed to quantify how local environmental conditions and the presence of grazing interact as drivers of emissions of three key greenhouse gases, CO2, CH4 and N2O, in coastal wetlands of the Yukon Kuskokwim Delta. We explored the magnitude of emissions across gradients of soil temperature and water table depth, and across vegetation types related to the presence of grazing, ranging from no vegetation through grazed and ungrazed vegetation. We also investigated emissions from grazed areas using experimental manipulations of the timing of grazing and advancement of the growing season. We found that local environmental conditions and use by grazers exert interacting controls on emissions of CO2, CH4 and N2O. Emissions of CO2 and CH4 were positively related to soil temperature and CH4 emissions were inversely related to water table depth, but the relationship varied by vegetation type. Net emissions of CO2 were greatest in ungrazed vegetation types (6.62 umols CO2 m-2 sec-1; p=0.0007) whereas CH4 emissions were greatest in the grazed vegetation (122.56 nmols CH4 m-2 sec-1; p=0.037). Flux of N2O was less than 1 nmol N2O m-2 sec-1 across all landscape positions under typical grazing and temperature conditions, but emissions were stimulated to over 10 nmols m-2 sec-1 when grazing occurred early relative to a typical season. Our results indicate that environmental conditions and the presence of migratory herbivores are both

  19. Sectoral CO 2, CH 4, N 2O and SO 2 emissions from fossil fuel consumption in Nagpur City of Central India

    NASA Astrophysics Data System (ADS)

    Majumdar, Deepanjan; Gajghate, D. G.

    2011-08-01

    Emission inventory of CO 2, CH 4, N 2O and SO 2 has been prepared for Nagpur city in Central India for the year 2004. Data on fossil fuel (coal, light diesel oil, high speed diesel, petrol/gasoline, low sulphur heavy stock, furnace oil and kerosene) consumption in thermal power, industrial, transport and domestic sectors were collected. Thermal power sector had the maximum coal consumption followed by the industrial and domestic sectors, whereas kerosene, liquefied petroleum gas (LPG), diesel and gasoline were used only in any single sector. Total annual CO 2, CH 4, N 2O and SO 2 emissions from these fuels in Nagpur city for the year 2004 was found to be 14792418 MT (14.8 Tg), 4649 (4.6 Tg), 1529 (1.5 Tg) and 69093 (6.9 Tg), respectively, in which thermal power and domestic sector had the maximum share. Coal was found to be the major contributor to Green House Gas (GHG) and SO 2 emissions in all the sectors barring transport and domestic sectors. Carbon dioxide was the predominant GHG emitted by the selected sectors in terms of absolute emissions and also global warming contribution (GWC), though the share in the latter was lesser in magnitude due to higher global warming potential (GWP) of CH 4 and N 2O than CO 2. Thermal power sector had a share of 51% in total CO 2 emissions from all the sectors, followed by domestic, industrial and transport sectors having 27, 12 and 10% contributions, respectively. Share of thermal power sector in total SO 2 emissions was 61%, followed by 24% from industrial, 10% from domestic and 5% from transport sector.

  20. Simulating CH4 and N2O emissions from direct-seeded rice systems using the DeNitrification DeComposition (DNDC) model

    NASA Astrophysics Data System (ADS)

    Simmonds, M.; Li, C.; Lee, J.; Six, J.; Van Kessel, C.; Linquist, B.

    2015-12-01

    Process-based modeling of CH4 and N2O emissions from rice fields is a practical tool for conducting greenhouse gas inventories and estimating mitigation potentials of alternative practices at the scales of management and policy-making. However, few studies have evaluated site-level model performance in side-by-side field trials of various management practices during both the growing season and fallow periods. We empirically evaluated the DeNitrification-DeComposition (DNDC) model for estimating CH4 and N2O fluxes in California rice systems under varying management (N fertilizer application rate, type of seeding system, fallow period straw and water management), soil environments, and weather conditions. Five and nine site-year combinations were used for calibration and validation, respectively. The model was parameterized for two cultivars, M206 and Koshihikari, and able to simulate 30% and 78% of the measured variation in yields, respectively. A major strength of DNDC was in estimating general site-level seasonal CH4 emissions (R2 = 0.85). However, a major limitation was in simulating finer resolution of differences in CH4 emissions (or lack thereof) among side-by-side management treatments (range of 0.2-465% relative absolute deviation). Additionally, DNDC did not satisfactorily simulate fallow period CH4 emissions, or seasonal and fallow period N2O emissions across all sites with the exception of a few cases. Specifically, simulated CH4 emissions were oversensitive to fertilizer N rates, but lacked sensitivity to the type of seeding system and prior fallow period straw management. Additionally, N2O emissions were oversensitive to fertilizer N rates and field drainage. Sensitivity analysis showed that CH4 emissions were highly sensitive to changes in the root to total plant biomass ratio. Overall, uncertainty in model predictions was attributed to uncertainty in both the input parameters due to in-field spatiotemporal variability of soil properties, and in the

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

    PubMed

    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. PMID:26164270

  2. Modeling the CO2 and N2O Emissions From Stover Removal for Biofuel Production From Continuous Corn Production in Iowa

    NASA Astrophysics Data System (ADS)

    Paustian, K.; Killian, K.; Brenner, J.

    2003-12-01

    Corn stover, an agricultural residue, can be used as feedstock for near term bioethanol production and is available today at levels that can significantly impact energy supply. We evaluated the environmental impact of such a large-scale change in agricultural practices on green house gas production, soil erosion and soil carbon using the Century model. Estimates of soil C changes and GHG emissions were performed for the 99 counties in Iowa where previous environmental, management and erosion data was available. We employed climate, soil and historical management databases from a separate USDA-funded project as input to Century. RUSLE estimates of the residue requirements for acceptable soil loss rates under continuous corn agriculture were available from a previous study done Dr. Richard Nelson (Enersol Resources). Two mulch tillage and a no-till systems, where erosion estimates were available, were used as the basis for the simulations. Century simulations of these systems were run under a variety of stover removal rates. For each soil type within each county the model was run for 15 years (1980-1995) under continuous corn with convention tillage, and full residue return. Model simulation of crop yields and residue production were then calibrated to match those used by the Polysys model team at Oak Ridge and the simulation was repeated with the addition of the three corn tillage regimes, and several residue removal rates. County-average soil C changes (and net CO2 emissions) were calculated as area-weighted averages of the individual soil types in each county. For this study, we have utilized the IPCC approach to estimate annual N2O emissions. At low or zero residue removal rates, county-averaged soil C stocks were predicted to increase (i.e. net CO2 emissions are negative). Where the allowable residue removal rates (based on erosion tolerance) for mulch-tillage are on the order of 40-50% or more, the reduced input of C is such that the soils no longer sequester C

  3. Changes in CO2, N2O and NO Emissions in Response to Conventional Tillage and No-tillage Management Practices in the State of Rondonia, Brazil

    NASA Astrophysics Data System (ADS)

    Passianoto, C. C.; Ahrens, T. D.; Feigl, B. J.; Steudler, P. A.; Do Carmo, J. B.; Melillo, J. M.

    2002-12-01

    Land management in the Brazilian State of Rondonia is undergoing a new phase at the start of 21st century. In the 1970s and afterwards, vast tracts of tropical forest were cleared and planted to pasture for cattle grazing. With decades of use, the productivity of these pastures has declined. Now, in an effort to restore productivity, new land management regimes are being implemented that involve either tillage or no-tillage options combined with various combinations of fertilizer application, herbicide use and the planting of a cash crop prior to the planting of forage grasses. We are studying a subset of these restoration practices in a large-scale (>3 ha), replicated field experiment in an area of degraded pasture at Fazenda Nova Vida, a 22,000 ha cattle ranch in central Rondonia. Here we report on the emissions of carbon dioxide (CO2), nitrous oxide (N2O) and nitric oxide (NO) from the initial phases (first six months) of three of the treatments. The treatments are - 1) control; 2) conventional tillage followed by planting of forage grass (Brachiaria brizantha) and fertilizer additions; 3) no-tillage/herbicide treatment followed by two plantings, the first being a cash crop of rice followed by forage grass. In treatment 3, the rice was fertilized. Relative to the control, tillage increased CO2 emission by 37% over the first two months, while the no-tillage/herbicide regime decreased CO2 emissions by 7% over the same period. The cumulative N2O emissions over the first two months from the tillage regime (0.94 kg N ha-1) were much higher than the N2O releases from either the no-tillage/herbicide regime (0.64 kg N ha-1) or the control treatment (0.04 kg N ha-1). The highest levels of N2O fluxes from both management regimes were observed following nitrogen fertilizations. The cumulative NO releases over the first two months were largest in the tillage treatment (0.98 kg N ha-1), intermediate in the no-tillage treatment (0.72 kg N ha-1), and smallest in the control

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

    NASA Astrophysics Data System (ADS)

    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.

  5. A quantum cascade laser absorption spectrometer devoted to the in situ measurement of atmospheric N2O and CH4 emission fluxes

    NASA Astrophysics Data System (ADS)

    Mappé, I.; Joly, L.; Durry, G.; Thomas, X.; Decarpenterie, T.; Cousin, J.; Dumelie, N.; Roth, E.; Chakir, A.; Grillon, P. G.

    2013-02-01

    This paper describes a Quantum Cascade Laser Absorption Spectrometer, called "QCLAS" that was developed to monitor in situ greenhouse gases like N2O and CH4, at high temporal resolution and with a high accuracy. The design of the laser sensor is reported as well as its performances in terms of precision error and field deployment capabilities. Finally, to demonstrate the efficiency and the robustness of QCLAS and its suitability for gas emission monitoring and for the determination of fluxes, we report the results from a field campaign, that took place in the Wallis and Futuna Islands in 2011, to investigate the impact of environmental intensive pig farming.

  6. Automated online measurement of N2, N2O, NO, CO2, and CH4 emissions based on a gas-flow-soil-core technique.

    PubMed

    Liao, Tingting; Wang, Rui; Zheng, Xunhua; Sun, Yang; Butterbach-Bahl, Klaus; Chen, Nuo

    2013-11-01

    The gas-flow-soil-core (GFSC) technique allows to directly measure emission rates of denitrification gases of incubated soil cores. However, the technique was still suffering some drawbacks such as inadequate accuracy due to asynchronous detection of dinitrogen (N2) and other gases and low measurement frequency. Furthermore, its application was limited due to intensive manual operation. To overcome these drawbacks, we updated the GFSC system as described by Wang et al. (2011) by (a) using both a chemiluminescent detector and a gas chromatograph detector to measure nitric oxide (NO), (b) synchronizing the measurements of N2, NO, nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4), and (c) fully automating the sampling/analysis of all the gases. These technical modifications significantly reduced labor demands by at least a factor of two, increased the measurement frequency from 3 to 6 times per day and resulted in remarkable improvements in measurement accuracy (with detection limits of 0.5, 0.01, 0.05, 2.3 and 0.2μgN or Ch(-1)kg(-1)ds, or 17, 0.3, 1.8, 82, and 6μgN or Cm(-2)h(-1), for N2, N2O, NO, CO2, and CH4, respectively). In some circumstances, the modified system measured significantly more N2 and CO2 and less N2O and NO because of the enhanced measurement frequency. The modified system distinguished the differences in emissions of the denitrification gases and CO2 due to a 20% change in initial carbon supplies. It also remarkably recovered approximately 90% of consumed nitrate during incubation. These performances validate the technical improvement, and indicate that the improved GFSC system may provide a powerful research tool for obtaining deeper insights into the processes of soil carbon and nitrogen transformation during denitrification. PMID:24184044

  7. Regional-specific emission inventory for NH 3, N 2O, and CH 4 via animal farming in South, Southeast, and East Asia

    NASA Astrophysics Data System (ADS)

    Yamaji, Kazuyo; Ohara, Toshimasa; Akimoto, Hajime

    Ammonia, nitrous oxide, and methane emission from animal farming of South, Southeast, and East Asia, in 2000, was estimated at about 4.7 Tg NH 3-N, 0.51 Tg N 2O-N, and 29.9 Tg CH 4, respectively, using the FAO database and countries' statistic databases as activity data, and emission factors taking account of regional characteristics. Most of these atmospheric components, up to 60-80%, were produced in China and India. Pakistan, Bangladesh, and Indonesia, which were large source countries next to China and India, contributed more than a few percent of total emission of each atmospheric component. The largest emission livestock were cattle whose contribution was considerably high in South, Southeast, and East Asia; more than one-fourth of ammonia and nitrous oxide emissions: more than half of methane emission. The other major livestock for nitrous oxide and ammonia emissions were pigs. For methane emission, buffaloes were second source livestock. To provide spatial distributions of these gases, the emissions of county and district level were allocated into each 0.5° grid by means of the weighting by high-resolution land cover datasets. The regions with considerable high emissions of all components were able to be found at the Ganges delta and the Yellow River basin. The spatial distributions for ammonia and nitrous oxide emissions were similar but had a substantial difference from methane distribution.

  8. The contribution of hydroxylamine content to spatial variability of N2O formation in soil of a Norway spruce forest

    NASA Astrophysics Data System (ADS)

    Liu, Shurong; Herbst, Michael; Bol, Roland; Gottselig, Nina; Pütz, Thomas; Weymann, Daniel; Wiekenkamp, Inge; Vereecken, Harry; Brüggemann, Nicolas

    2016-04-01

    Hydroxylamine (NH2OH), a reactive intermediate of several microbial nitrogen turnover processes, is a potential precursor of nitrous oxide (N2O) formation in the soil. However, the contribution of soil NH2OH to soil N2O emission rates in natural ecosystems is unclear. Here, we determined the spatial variability of NH2OH content and potential N2O emission rates of organic (Oh) and mineral (Ah) soil layers of a Norway spruce forest, using a recently developed analytical method for the determination of soil NH2OH content, combined with a geostatistical Kriging approach. Potential soil N2O emission rates were determined by laboratory incubations under oxic conditions, followed by gas chromatographic analysis and complemented by ancillary measurements of soil characteristics. Stepwise multiple regressions demonstrated that the potential N2O emission rates, NH2OH and nitrate (NO3-) content were spatially highly correlated, with hotspots for all three parameters observed in the headwater of a small creek flowing through the sampling area. In contrast, soil ammonium (NH4+) was only weakly correlated with potential N2O emission rates, and was excluded from the multiple regression models. While soil NH2OH content explained the potential soil N2O emission rates best for both layers, also NO3- and Mn content turned out to be significant parameters explaining N2O formation in both soil layers. The Kriging approach was improved markedly by the addition of the co-variable information of soil NH2OH and NO3- content. The results indicate that determination of soil NH2OH content could provide crucial information for the prediction of the spatial variability of soil N2O emissions.

  9. Isotopologue ratios of N2O and N2 measurements underpin the importance of denitrification in differently N-loaded riparian alder forests.

    PubMed

    Mander, Ulo; Well, Reinhard; Weymann, Daniel; Soosaar, Kaido; Maddison, Martin; Kanal, Arno; Lõhmus, Krista; Truu, Jaak; Augustin, Jürgen; Tournebize, Julien

    2014-10-21

    Known as biogeochemical hotspots in landscapes, riparian buffer zones exhibit considerable potential concerning mitigation of groundwater contaminants such as nitrate, but may in return enhance the risk for indirect N2O emission. Here we aim to assess and to compare two riparian gray alder forests in terms of gaseous N2O and N2 fluxes and dissolved N2O, N2, and NO3(-) in the near-surface groundwater. We further determine for the first time isotopologue ratios of N2O dissolved in the riparian groundwater in order to support our assumption that it mainly originated from denitrification. The study sites, both situated in Estonia, northeastern Europe, receive contrasting N loads from adjacent uphill arable land. Whereas N2O emissions were rather small at both sites, average gaseous N2-to-N2O ratios inferred from closed-chamber measurements and He-O laboratory incubations were almost four times smaller for the heavily loaded site. In contrast, groundwater parameters were less variable among sites and between landscape positions. Campaign-based average (15)N site preferences of N2O (SP) in riparian groundwater ranged between 11 and 44 ‰. Besides the strong prevalence of N2 emission over N2O fluxes and the correlation pattern between isotopologue and water quality data, this comparatively large range highlights the importance of denitrification and N2O reduction in both riparian gray alder stands. PMID:25264900

  10. Effects of soil spatial resolution on quantifying CH4 and N2O emissions from rice fields in the Tai Lake region of China by DNDC model

    NASA Astrophysics Data System (ADS)

    Yu, D. S.; Yang, H.; Shi, X. Z.; Warner, E. D.; Zhang, L. M.; Zhao, Q. G.

    2011-06-01

    Fourteen grid data sets of different cell resolutions were generated, from 0.5 × 0.5 km to 64 × 64 km, to estimate CH4 and N2O emissions from paddy soils in the Tai Lake region of China using the Denitrification-Decomposition (DNDC) model. The grids were derived from a polygon-based data set (1:50,000 digital soil map/database), which was the most detailed soil database for the region. Comparison of simulated CH4 and N2O concentrations from input of the 14 grid data sets with the original polygon data demonstrated (1) no distinct variability (relative errors <5%) of the results when grid data sets of cell size ≤2 km were used as input for the DNDC model; (2) slight variability (<10%) in the results when grid data sets with cell size in the range of 2 to 8 km were used as input; and (3) distinct variability (>10%) in the results when grid data sets with cell size of >8 km were applied as input. A grid data set with a cell size of 8 km was found to be optimal based on accuracy and computational efficiency of DNDC simulations. The results can be used as a guideline for optimizing field sampling strategies for locations where there is a lack of or insufficient soil data, whereby soil data can be collected through sampling in cell centers of designed grid frames.

  11. Effects of warming and drought on potential N2O emissions and denitrifying bacteria abundance in grasslands with different land-use.

    PubMed

    Keil, Daniel; Niklaus, Pascal A; von Riedmatten, Lars R; Boeddinghaus, Runa S; Dormann, Carsten F; Scherer-Lorenzen, Michael; Kandeler, Ellen; Marhan, Sven

    2015-07-01

    Increased warming in spring and prolonged summer drought may alter soil microbial denitrification. We measured potential denitrification activity and denitrifier marker gene abundances (nirK, nirS, nosZ) in grasslands soils in three geographic regions characterized by site-specific land-use indices (LUI) after warming in spring, at an intermediate sampling and after summer drought. Potential denitrification was significantly increased by warming, but did not persist over the intermediate sampling. At the intermediate sampling, the relevance of grassland land-use intensity was reflected by increased potential N2O production at sites with higher LUI. Abundances of total bacteria did not respond to experimental warming or drought treatments, displaying resilience to minor and short-term effects of climate change. In contrast, nirS- and nirK-type denitrifiers were more influenced by drought in combination with LUI and pH, while the nosZ abundance responded to the summer drought manipulation. Land-use was a strong driver for potential denitrification as grasslands with higher LUI also had greater potentials for N2O emissions. We conclude that both warming and drought affected the denitrifying communities and the potential denitrification in grassland soils. However, these effects are overruled by regional and site-specific differences in soil chemical and physical properties which are also related to grassland land-use intensity. PMID:26092950

  12. N2O emission from urine in the soil in the beef production in Southeast Brazil: soil moisture content and temperature effects

    NASA Astrophysics Data System (ADS)

    Simões Barneze, Arlete; Mancebo Mazzetto, Andre; Fernandes Zani, Caio; Siqueira Neto, Marcos; Clemente Cerri, Carlos

    2014-05-01

    Pasture expansion in Brazil has shown an increase in 4.5% per year, and a total cattle herd of about 200 millions in 2010. Associated to animal husbandry there are emissions of N2O (nitrous oxide) and other gases to the atmosphere. The liquid manure contributes to emitte 5% of the total N2O emissions. The urea content of cattle urine will readily hydrolyze to form ammonium after deposition to the soil. Nitrous oxide may then be emitted through the microbiological processes of nitrification and denitrification. Important factors can influence on these processes and consequently in nitrous oxide emissions, as soil water content and temperature (Bolan et al., 2004; Luo et al., 2008). The main goal of this research was to determine the soil water content and temperature influence on N2O emissions from urine depositions on the soil. In order to achieve the objective, soil incubation experiment was conducted in laboratory conditions at three levels of water-filled pore space (40%, 60% and 80% WFPS) and two temperatures (25ºC and 35ºC) with and without urine, with five replicates each. The soil used in this study was collected from the 0-10 cm layer of a grassland field in Southeast of Brazil and classified as Nitisols. For each measurement, the Kilner jar was hermetically sealed by replacing the lid and a first gas sample was immediately taken (time-zero, t0 sample) using a syringe and stored in a pre-evacuated gas vial. After 30 minutes the headspace of each jar was sampled again (time-thirty, t_30 sample). The lids were then removed and kept off until the next sampling day. Nitrous oxide concentrations in the sampled air were measured using a SRI Gas Chromatograph (Model 8610C). Gas fluxes were calculated by fitting linear regressions through the data collected at t0 and t_30 and were corrected for temperature and amount of soil incubated. Gas measurements were carried out up to 55 days. To determine the statistical significance, Tukey tests were carried out at 0

  13. Parameter-induced uncertainty quantification of soil N2O, NO and CO2 emission from Höglwald spruce forest (Germany) using the LandscapeDNDC model

    NASA Astrophysics Data System (ADS)

    Rahn, K.-H.; Werner, C.; Kiese, R.; Haas, E.; Butterbach-Bahl, K.

    2012-10-01

    Assessing the uncertainties of simulation results of ecological models is becoming increasingly important, specifically if these models are used to estimate greenhouse gas emissions on site to regional/national levels. Four general sources of uncertainty effect the outcome of process-based models: (i) uncertainty of information used to initialise and drive the model, (ii) uncertainty of model parameters describing specific ecosystem processes, (iii) uncertainty of the model structure, and (iv) accurateness of measurements (e.g., soil-atmosphere greenhouse gas exchange) which are used for model testing and development. The aim of our study was to assess the simulation uncertainty of the process-based biogeochemical model LandscapeDNDC. For this we set up a Bayesian framework using a Markov Chain Monte Carlo (MCMC) method, to estimate the joint model parameter distribution. Data for model testing, parameter estimation and uncertainty assessment were taken from observations of soil fluxes of nitrous oxide (N2O), nitric oxide (NO) and carbon dioxide (CO2) as observed over a 10 yr period at the spruce site of the Höglwald Forest, Germany. By running four independent Markov Chains in parallel with identical properties (except for the parameter start values), an objective criteria for chain convergence developed by Gelman et al. (2003) could be used. Our approach shows that by means of the joint parameter distribution, we were able not only to limit the parameter space and specify the probability of parameter values, but also to assess the complex dependencies among model parameters used for simulating soil C and N trace gas emissions. This helped to improve the understanding of the behaviour of the complex LandscapeDNDC model while simulating soil C and N turnover processes and associated C and N soil-atmosphere exchange. In a final step the parameter distribution of the most sensitive parameters determining soil-atmosphere C and N exchange were used to obtain the

  14. Parameter-induced uncertainty quantification of soil N2O, NO and CO2 emission from Höglwald spruce forest (Germany) using the LandscapeDNDC model

    NASA Astrophysics Data System (ADS)

    Rahn, K.-H.; Werner, C.; Kiese, R.; Haas, E.; Butterbach-Bahl, K.

    2012-04-01

    Assessing the uncertainties of simulation results of ecological models is becoming of increasing importance, specifically if these models are used to estimate greenhouse gas emissions at site to regional/national levels. Four general sources of uncertainty effect the outcome of process-based models: (i) uncertainty of information used to initialise and drive the model, (ii) uncertainty of model parameters describing specific ecosystem processes, (iii) uncertainty of the model structure and (iv) accurateness of measurements (e.g. soil-atmosphere greenhouse gas exchange) which are used for model testing and development. The aim of our study was to assess the simulation uncertainty of the process-based biogeochemical model LandscapeDNDC. For this we set up a Bayesian framework using a Markov Chain Monte Carlo (MCMC) method, to estimate the joint model parameter distribution. Data for model testing, parameter estimation and uncertainty assessment were taken from observations of soil fluxes of nitrous oxide (N2O), nitric oxide (NO), and carbon dioxide (CO2) as observed over a 10 yr period at the spruce site of the Höglwald Forest, Germany. By running four independent Markov Chains in parallel with identical properties (except for the parameter start values), an objective criteria for chain convergence developed by Gelman et al. (2003) could be used. Our approach showed that by means of the joined parameter distribution, we were able not only to limit the parameter space and specify the probability of parameter values, but also to assess the complex dependencies among model parameters used for simulating soil C and N trace gas emissions. This helped to improve the understanding of the behaviour of the complex LandscapeDNDC model while simulating soil C and N turnover processes and associated C and N soil-atmosphere exchange. In a final step the parameter distribution of the most sensitive parameters determining soil-atmosphere C and N exchange were used to obtain the

  15. Direct emissions of N2O, CO 2, and CH 4 from A/A/O bioreactor systems: impact of influent C/N ratio.

    PubMed

    Ren, Yangang; Wang, Jinhe; Xu, Li; Liu, Cui; Zong, Ruiqiang; Yu, Jianlin; Liang, Shuang

    2015-06-01

    Direct emissions of N2O, CO2, and CH4, three important greenhouse gases (GHGs), from biological sewage treatment process have attracted increasing attention worldwide, due to the increasing concern about climate change. Despite the tremendous efforts devoted to understanding GHG emission from biological sewage treatment process, the impact of influent C/N ratios, in terms of chemical oxygen demand (COD)/total nitrogen (TN), on an anaerobic/anoxic/oxic (A/A/O) bioreactor system has not been investigated. In this work, the direct GHG emission from A/A/O bioreactor systems fed with actual sewage was analyzed under different influent C/N ratios over a 6-month period. The results showed that the variation in influent carbon (160 to 500 mg/L) and nitrogen load (35 to 95 mg/L) dramatically influenced pollutant removal efficiency and GHG production from this process. In the A/A/O bioreactor systems, the GHG production increased from 26-39 to 112-173 g CO2-equivalent as influent C/N ratios decreased from 10.3/10.7 to 3.5/3.8. Taking consideration of pollutant removal efficiency and direct biogenic GHG (N2O, CO2, and CH4) production, the optimum influent C/N ratio was determined to be 7.1/7.5, at which a relatively high pollutant removal efficiency and meanwhile a low level of GHG production (30.4 g CO2-equivalent) can be achieved. Besides, mechanical aeration turned out to be the most significant factor influencing GHG emission from the A/A/O bioreactor systems. PMID:25850740

  16. Seasonal and diurnal variability of N2O emissions from a full-scale municipal wastewater treatment plant.

    PubMed

    Daelman, Matthijs R J; van Voorthuizen, Ellen M; van Dongen, Udo G J M; Volcke, Eveline I P; van Loosdrecht, Mark C M

    2015-12-01

    During nitrogen removal in conventional activated sludge processes, nitrous oxide can be emitted. With a global warming potential of 298 CO2-equivalents it is an important greenhouse gas that affects the sustainability of wastewater treatment. The present study reports nitrous oxide emission data from a 16 month monitoring campaign on a full-scale municipal wastewater treatment. The emission demonstrated a pronounced diurnal and seasonal variability. This variability was compared with the variability of a number of process variables that are commonly available on a municipal wastewater treatment plant. On a seasonal timescale, the occurrence of peaks in the nitrite concentration correlated strongly with the emission. The diurnal trend of the emission coincided with the diurnal trend of the nitrite and nitrate concentrations in the tank, suggesting that suboptimal oxygen concentrations may induce the production of nitrous oxide during both nitrification and denitrification. This study documents an unprecedented dataset that could serve as a reference for further research. PMID:26188527

  17. Spatial variability of greenhouse gases emissions (CO2, CH4, N2O) in a tropical hydroelectric reservoir flooding primary forest (Petit Saut Reservoir, French Guiana)

    NASA Astrophysics Data System (ADS)

    Cailleaud, Emilie; Guérin, Frédéric; Bouillon, Steven; Sarrazin, Max; Serça, Dominique

    2014-05-01

    At the Petit Saut Reservoir (PSR, French Guiana, South America), vertical profiles were performed at 5 stations in the open waters (OW) and 6 stations in two shallow flooded forest (FF) areas between April 2012 and September 2013. Measurements included physico-chemical parameters, ammonium, nitrate and dissolved greenhouse gas (CO2, CH4, N2O) concentrations, dissolved and particulate organic carbon (DOC, POC) and nitrogen (PN), δ13C-POC and δ15N-PN . The diffusive fluxes were calculated from surface concentrations. The aim of this study was to estimate the spatial variations of greenhouse gas emissions at a dentrical hydroelectric reservoir located in the tropics and flooding primary forest. Twenty years after impoundment, the water column of the PSR is permanently and tightly stratified thermally in the FF whereas in the OW, the thermal gradients are not as stable. The different hydrodynamical behaviours between the two different zones have significant consequences on the biogeochemistry: oxygen barely diffuses down to the hypolimnion in the FF whereas destratification occurs sporadically during the rainy season in the OW. Although we found the same range of POC in the FF and the OW (2.5-29 μmol L-1) and 20% more DOC at the bottom of OW than in the FF (229-878 μmol L-1), CO2 and CH4 concentrations were always significantly higher in the FF (CO2: 11-1412 μmol L-1, CH4: 0.001-1015 μmol L-1) than in the OW. On average, the CO2 concentrations were 30-40% higher in the FF than in the OW and the CH4 concentrations were three times higher in the FF than in the OW. The δ13C-POC and C:N values did not suggest substantial differences in the sources of OM between the FF and OW. At all stations, POC at the bottom has an isotopic signature slightly lighter than the terrestrial OM in the surrounding forest whereas the isotopic signature of surface POM would result from phytoplankton and methanotrophs. The vertical profiles of nitrogen compounds reveal that the main

  18. Assessment of nitrate leakage and N2O emission from five environmental-friendly agricultural practices using fuzzy logic method and empirical formula.

    PubMed

    Qin, Lihuan; Wang, Yan; Wu, Yongfeng; Wang, Qian; Luo, Liangguo

    2015-06-01

    Agricultural nonpoint source pollution in China has been the major environmental problem, so environmental-friendly agricultural practices (EAPs) must be promoted to improve environmental quality. However, the most suitable practices for each agricultural region must first be identified. Thus, in the presented study a fuzzy-logic method and a revised empirical formula were used to assess nitrate leakage and N2O emissions, respectively, and to compare five EAPs in Xinxiang, a major grain-producing county in Henan Province, China. The required information was collected in face-to-face interviews with 10 extension service experts from the county, using a questionnaire to explore their opinions of the EAPs currently adopted by smallholder farmers, as well as the amounts, frequencies, varieties and proportions of nitrogen fertilizers applied annually. The results indicate that reduced tillage, soil testing and fertilizer recommendations would be the most appropriate practices to initially promote on a large scale in Xinxiang. PMID:26003184

  19. Developing a regional scale approach for modelling the impacts of fertiliser regime on N2O emissions in Ireland

    NASA Astrophysics Data System (ADS)

    Zimmermann, Jesko; Jones, Michael

    2016-04-01

    Agriculture can be significant contributor to greenhouse gas emissions, this is especially prevalent in Ireland where the agricultural sector accounts for a third of total emissions. The high emissions are linked to both the importance of agriculture in the Irish economy and the focus on dairy and beef production. In order to reduce emissions three main categories are explored: (1) reduction of methane emissions from cattle, (2) reduction of nitrous oxide emissions from fertilisation, and (3) fostering the carbon sequestration potential of soils. The presented research focuses on the latter two categories, especially changes in fertiliser amount and composition. Soil properties and climate conditions measured at the four experimental sites (two silage and two spring barley) were used to parameterise four biogeochemical models (DayCent, ECOSSE, DNDC 9.4, and DNDC 9.5). All sites had a range of different fertiliser regimes applied. This included changes in amount (0 to 500 kg N/ha on grassland and 0 to 200 kg N/ha on arable fields), fertiliser type (calcium ammonium nitrate and urea), and added inhibitors (the nitrification inhibitor DCD, and the urease inhibitor Agrotain). Overall, 20 different treatments were applied to the grassland sites, and 17 to the arable sites. Nitrous oxide emissions, measured in 2013 and 2014 at all sites using closed chambers, were made available to validate model results for these emissions. To assess model performance for the daily measurements, the Root Mean Square Error (RMSE) was compared to the measured 95% confidence interval of the measured data (RMSE95). Bias was tested comparing the relative error (RE) the 95 % confidence interval of the relative error (RE95). Preliminary results show mixed model performance, depending on the model, site, and the fertiliser regime. However, with the exception of urea fertilisation and added inhibitors, all scenarios were reproduced by at least one model with no statistically significant total

  20. EPA (ENVIRONMENTAL PROTECTION AGENCY) WORKSHOP ON N2O EMISSION FROM COMBUSTION (DURHAM, NC., FEBRUARY 13-14, 1986)

    EPA Science Inventory

    The report summarizes the dialogue and interaction which took place during an EPA sponsored workshop addressing nitrous oxide (N20) emissions from fossil fuel combustion. Prior research had identified N20 as a trace gas potentially contributing to depletion of stratospheric ozone...