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Kaiqiang Zhang, Stefan T Thynell
The dimerization of HNO and subsequent yield of N2O in aqueous solution are studied based on the theoretical calculations and kinetic simulations. The initial dimerization reactions were computed at various levels of theory and large divergence was observed in the predictions of the gas-phase free energies. The T1 diagnostics at CCSD(T)/aug-cc-pVTZ suggests multireference characteristics of the HNO dimers and the transition states. The solution-phase free energies were obtained using the wB97XD method and the SMD solvation model...
May 24, 2017: Journal of Physical Chemistry. A
Shohei Riya, Yuki Takeuchi, Sheng Zhou, Akihiko Terada, Masaaki Hosomi
A pulse of nitrous oxide (N2O) emission has been observed following the disappearance of floodwater by drainage. However, its mechanism is not well understood. We conducted a column study to clarify the mechanism for N2O production during floodwater disappearance by using a microsensor and determining the bacterial gene expression. An increase in N2O flux was observed following floodwater disappearance after the addition of NH4(+), with a corresponding increase in the concentrations of NO3(-) and dissolved N2O in the oxic and anoxic soil layers, respectively...
May 23, 2017: Environmental Science and Pollution Research International
Timothy J Clough, Gary J Lanigan, Cecile A M de Klein, Md Sainur Samad, Sergio E Morales, David Rex, Lars R Bakken, Charlotte Johns, Leo M Condron, Jim Grant, Karl G Richards
Intensively managed agricultural pastures contribute to N2O and N2 fluxes resulting in detrimental environmental outcomes and poor N use efficiency, respectively. Besides nitrification, nitrifier-denitrification and heterotrophic denitrification, alternative pathways such as codenitrification also contribute to emissions under ruminant urine-affected soil. However, information on codenitrification is sparse. The objectives of this experiment were to assess the effects of soil moisture and soil inorganic-N dynamics on the relative contributions of codenitrification and denitrification (heterotrophic denitrification) to the N2O and N2 fluxes under a simulated ruminant urine event...
May 19, 2017: Scientific Reports
R Baran, L Valentin, J-M Krafft, T Grzybek, P Glatzel, S Dzwigaj
Manganese-containing BEA zeolites, MnxSiBEA (x = 1-4 wt%) and Mn(I.E.)AlBEA, were prepared by a two-step post-synthesis method and a conventional wet ion-exchange, respectively, and applied as catalysts in the selective catalytic reduction of NO with ammonia (NH3-SCR). The physicochemical analysis of zeolite properties by high-energy-resolution fluorescence-detected XANES (HERFD-XANES) and X-ray emission spectroscopy (XES) uncovered that the coordination, geometry and oxidation state of Mn species are strongly related to the preparation method...
May 17, 2017: Physical Chemistry Chemical Physics: PCCP
C Lauzin, A J Barclay, K H Michaelian, N Moazzen-Ahmadi
Three combination bands involving intermolecular modes of the most stable isomer of the OC-N2O van der Waals complex have been observed, two in the carbon monoxide CO stretch region (∼2150 cm(-1)) and one in the ν3 asymmetric stretch region of N2O (∼2223 cm(-1)). Vibrational assignment is achieved by comparison with data recently published ( Barclay , A. ; et al. Chem. Phys. Lett. 2016 , 62 , 651 ), concerning OC-CO2. Two of these bands involve the same intermolecular mode, one with the CO stretch and the other with the ν3 asymmetric stretch of N2O...
May 16, 2017: Journal of Physical Chemistry. A
Engil Isadora Pujol Pereira, Rafaela Feola Conz, Johan Six
The potential of biochar to prevent nitrogen (N) losses and improve plant performance were studied across various levels of N input for two growing seasons in mesocosms simulating an organic lettuce production system. A silt loam soil was amended with pine chip (PC) and walnut shell (WS) biochar (10tha(-1)) in combination with five organic N fertilization rates (0, 56, 112, 168, and 225kgNha(-1)). The N output through harvest, leachate, and N2O emissions were measured to assess N utilization and environmental losses of biochar-amended soils...
May 10, 2017: Science of the Total Environment
Man Yang, Xianfeng Chen, Yujie Wang, Bihe Yuan, Yi Niu, Ying Zhang, Ruoyu Liao, Zumin Zhang
In order to analyze the thermal decomposition characteristics of ammonium nitrate (AN), its thermal behavior and stability under different conditions are studied, including different atmospheres, heating rates and gas flow rates. The evolved decomposition gases of AN in air and nitrogen are analyzed with a quadrupole mass spectrometer. Thermal stability of AN at different heating rates and gas flow rates are studied by differential scanning calorimetry, thermogravimetric analysis, paired comparison method and safety parameter evaluation...
April 28, 2017: Journal of Hazardous Materials
D Liang, F Sun, M A Wattiaux, V E Cabrera, J L Hedtcke, E M Silva
Organic agriculture continues to expand in the United States, both in total hectares and market share. However, management practices used by dairy organic producers, and their resulting environmental impacts, vary across farms. This study used a partial life cycle assessment approach to estimate the effect of different feeding strategies and associated crop production on greenhouse gas emissions (GHG) from Wisconsin certified organic dairy farms. Field and livestock-driven emissions were calculated using 2 data sets...
May 10, 2017: Journal of Dairy Science
Stefanie Schulz, Angelika Kölbl, Martin Ebli, Franz Buegger, Michael Schloter, Sabine Fiedler
More than 50% of all anthropogenic N2O emissions come from the soil. Drained Histosols that are used for agricultural purposes are particularly potent sources of denitrification due to higher stocks of organic matter and fertiliser application. However, conditions that favour denitrification can vary considerably across a field and change significantly throughout the year. Spatial and temporal denitrifier dynamics were assessed in a drained, intensely managed Histosol by focusing on the genetic nitrite and N2O reduction potential derived from the abundance of nirK, nirS and nosZ genes...
May 11, 2017: Microbial Ecology
Yongsheng Wang, Yansui Liu, Ruliang Liu, Aiping Zhang, Shiqi Yang, Hongyuan Liu, Yang Zhou, Zhengli Yang
The efficacy of biochar as an environmentally friendly agent for non-point source and climate change mitigation remains uncertain. Our goal was to test the impact of biochar amendment on paddy rice nitrogen (N) uptake, soil N leaching, and soil CH4 and N2O fluxes in northwest China. Biochar was applied at four rates (0, 4.5, 9 and13.5 t ha(-1) yr(-1)). Biochar amendment significantly increased rice N uptake, soil total N concentration and the abundance of soil ammonia-oxidizing archaea (AOA), but it significantly reduced the soil NO3(-)-N concentration and soil bulk density...
May 9, 2017: Scientific Reports
Tao Liu, Yongchao Liang, Guixin Chu
Nitrification inhibitors (NIs) have been used extensively to reduce nitrogen losses and increase crop nitrogen nutrition. However, information is still scant regarding the influence of NIs on nitrogen transformation, nitrous oxide (N2O) emission and nitrogen utilization in plastic-film-mulched calcareous soil under high frequency drip-fertigated condition. Therefore, a field trial was conducted to evaluate the effect of nitrapyrin (2-chloro-6-(trichloromethyl)-pyridine) on soil mineral nitrogen (N) transformation, N2O emission and nitrogen use efficiency (NUE) in a drip-fertigated cotton-growing calcareous field...
2017: PloS One
Yunhai Bai, Manos Mavrikakis
Periodic, self-consistent density functional theory (DFT-GGA, PW91) calculations are used to study the reaction mechanism for nitric oxide (NO) reduction by hydrogen (H2) on Pt(100). Energetics of various N-O activation paths, including both direct and hydrogen-assisted N-O bond-breaking paths, and the formation of three different N-containing products (N2, N2O, and NH3), are systematically studied. On the basis of our analysis, NO* dissociation has a lower barrier than NO* hydrogenation to HNO* or NOH*, and therefore, the direct NO dissociation path is predicted to dominate N-O activation on clean Pt(100)...
May 8, 2017: Journal of Physical Chemistry. B
S Descloux, V Chanudet, D Serça, F Guérin
Two greenhouse gases -methane (CH4) and nitrous oxide (N2O) - were monitored monthly during one year (2011) at the Eguzon Reservoir in France. The objective of the study was to quantify for the first time in a temperate area the total emissions of these gases through the main emission pathways (diffusion and bubbling from the reservoir, degassing and downstream diffusion). The reservoir was impounded in 1926 and had, in 2011, a eutrophic status promoting high organic matter degradation and nitrification-denitrification, all favouring CH4 and N2O production...
April 28, 2017: Science of the Total Environment
Osvaldo D Frutos, Irene Cortes, Sara Cantera, Esther Arnaiz, Raquel Lebrero, Raúl Muñoz
N2O represents ∼6% of the global greenhouse gas emission inventory and the most important O3-depleting substance emitted in this 21st century. Despite its environmental relevance, little attention has been given to cost-effective and environmentally friendly N2O abatement methods. Here we examined, the potential of a bubble column (BCR) and an internal loop airlift (ALR) bioreactors of 2.3 L for the abatement of N2O from a nitric acid plant emission. The process was based on the biological reduction of N2O by Paracoccus denitrificans using methanol as a carbon/electron source...
May 11, 2017: Environmental Science & Technology
Eric M Enanga, Nora J Casson, Tarrah A Fairweather, Irena F Creed
Most forest nitrogen budgets are imbalanced, with nitrogen inputs exceeding nitrogen outputs. The denitrification products nitrous oxide (N2O) and dinitrogen (N2) represent often-unmeasured fluxes that may close the gap between explained nitrogen inputs and outputs. Gaseous N2O and N2 effluxes, dissolved N2O flux, and traditionally measured dissolved nitrogen species (i.e., nitrate, ammonium, and dissolved organic nitrogen) were estimated to account for the annual nitrogen output along hillslope gradients from two catchments in a temperate forest...
May 3, 2017: Environmental Science & Technology
Yong-Jik Lee, Min-Kyu Park, Gun-Seok Park, Sang-Jae Lee, Sang Jun Lee, Bradley Seokhan Kim, Jae-Ho Shin, Dong-Woo Lee
Denitrification is a crucial process for the global nitrogen cycle through the reduction of nitrates by heterotrophic bacteria. Denitrifying microorganisms play an important role in eliminating fixed nitrogen pollutants from the ecosystem, concomitant with N2O emission. Although many microbial denitrifiers have been identified, little is known about the denitrifying ability of the genus Geobacillus. Here, we report the first complete genome sequences of Geobacillus subterraneus KCTC 3922(T), isolated from Liaohe oil field in China, and G...
April 29, 2017: Journal of Biotechnology
Osvaldo D Frutos, Gonzalo Barriguín, Raquel Lebrero, Raúl Muñoz
The continuous abatement of a synthetic N2O emission from a nitric acid plant coupled with the simultaneously production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) copolymer and the coenzyme Q10 (CoQ10) in a bubble column reactor (BCR) was tested using methanol, glycerol and a mixture of sodium acetate-acetic acid (Ac-HAc) as a carbon and electron donor source. The BCRs were inoculated with Paracoccus denitrificans and supplied with the carbon/electron donor at a loading rate of 139gCm(-3)d(-1)...
April 26, 2017: Science of the Total Environment
Tongshuai Liu, Hongmin Dong, Zhiping Zhu, Bin Shang, Fubin Yin, Wanqin Zhang, Tanlong Zhou
Media depth (MD) and moisture content (MC) are two important factors that greatly influence biofilters performance. The purpose of this study was to investigate the combined effect of MC and MD on removing ammonia (NH3), hydrogen sulfide (H2S), and nitrous oxide (N2O) from swine barns. Biofiltration performance of different MDs and MCs combination based on the mixed medium of wood chips and compost were monitored. A 3×3 factorial design was adopted, which included three levels of the two factors (MC: 45%, 55%, and 67% (wet basis); MD: 0...
April 28, 2017: Journal of the Air & Waste Management Association
Amit Kumar, M P Sharma
The emissions of greenhouse gas (GHG) from soils are of significant importance for global warming. The biological and physico-chemical characteristics of soil affect the GHG emissions from soils of different land use types. Methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) production rates from six forest and agricultural soil types in the Koteshwar hydropower reservoir catchments located in the Uttarakhand, India, were estimated and their relations with physico-chemical characteristics of soils were examined...
May 2017: Environmental Monitoring and Assessment
M Rezaei Rashti, W J Wang, C R Chen, S H Reeves, C Scheer
Combined application of plant residues and N fertilisers strongly affect soil mineral N dynamics and N2O emissions depending on the quality of the plant residues, their application methods and other management strategies. We investigated the effect of combined application of two vegetable plant residues (cauliflower and sweet corn) and (15)N fertiliser on N dynamics and N2O emission in a glasshouse pot study. The experiment was conducted under two residue management practices (soil incorporation vs surface mulching) over 98days with growing basil (Ocimum basilicum) plants...
April 24, 2017: Science of the Total Environment
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