Science.gov

Sample records for pre-equilibrium emission effects

  1. Pre-Equilibrium Cluster Emission with Pickup and Knockout

    SciTech Connect

    Betak, E.

    2005-05-24

    We present a generalization of the Iwamoto-Harada-Bisplinghoff pre-equilibrium model of light cluster formation and emission, which is enhanced by allowing for possible admixtures of knockout for strongly coupled ejectiles, like {alpha}'s. The model is able to attain the Weisskopf-Ewing formula for compound-nucleus decay at long-time limit; it keeps the philosophy of pre-equilibrium decay during the equilibration stage and it describes the initial phase of a reaction as direct process(es) expressed using the language of the exciton model.

  2. Pre-equilibrium emission in neutron induced reactions on54,56Fe

    NASA Astrophysics Data System (ADS)

    Avrigeanu, M.; Ivaşcu, M.; Avrigeanu, V.

    1988-06-01

    The experimentally well known ( n, p), ( n, α) and ( n, 2 n) reaction excitation functions, from threshold to 20 MeV incident energy, and neutron and proton emission spectra at 14.8 MeV from54,56Fe targets are calculated in the frame of the Geometry-Dependent Hybrid pre-equilibrium emission model, including angular momentum and parity conservation, and the Hauser-Feshbach statistical model. Use of a consistent statistical model parameter set enables the validation of the pre-equilibrium emission model. Moreover, an enhanced pre-equilibrium emission from higher spin composite system states, associated with higher incoming orbital momenta, has been evidenced. Higher orbital momenta involved also in the emergent channels of the process are suggested by calculations of the residual nuclei level populations.

  3. Pre-equilibrium Emission and α-clustering in Nuclei

    NASA Astrophysics Data System (ADS)

    Gramegna, F.; Fabris, D.; Marchi, T.; Degerlier, M.; Fotina, O. V.; Kravchuk, V. L.; D'Agostino, M.; Morelli, L.; Appannababu, S.; Baiocco, G.; Barlini, S.; Bini, M.; Brondi, A.; Bruno, M.; Casini, G.; Cinausero, M.; Gelli, N.; Moro, R.; Olmi, A.; Pasquali, G.; Piantelli, S.; Poggi, G.; Valdrè, S.; Vardaci, E.

    2015-02-01

    The study of nuclear states built on clusters bound by valence neutrons in their molecular configurations is a field of large interest, which is being renewed by the availability of exotic beams: clustering is, in fact, predicted to become very important at the drip-line, where weakly bound systems will prevail. Although for light nuclei at an excitation energy close to the particle separation value there are experimental evidences of such structure effects, this is still not the case for heavier nuclear systems. Many attempts have been done using preformation alpha clustering models, but there is still a lack of experimental data capable to give a direct feedback. In particular, searching for alpha clustering effects in medium mass systems is still a challenge, which can give new hints in this subject. In the past we have studied the reactions 250, 192 and 130 MeV 16O + 116Sn, observing a significant increase in the fast emitted α-particle yield. This effect was ascribed to the presence of preformed a-clusters in the 16O projectile nucleus. In order to investigate these aspects, in a model independent way, a new experimental campaign has been performed with the GARFIELD + RCo set up, to compare results from two different reactions: a double magic a-cluster (16O) and a non-magic α-cluster projectile (19F) at the same beam velocity (16AMeV) have been chosen, impinging respectively on 65Cu and 62Ni targets, thus leading to the same 81Rb* compound nucleus. The angular distributions and the light charged particles emission spectra in coincidence with evaporation residues have been measured and analyzed. The preliminary results of the data analysis and the main features of the theoretical model used for their interpretation are presented.

  4. Probing the momentum dependence of the symmetry potential by the free n /p ratio of pre-equilibrium emission

    NASA Astrophysics Data System (ADS)

    Liu, He-Lei; Yong, Gao-Chan; Wen, De-Hua

    2015-02-01

    Based on an isospin and momentum-dependent transport model, we studied the effect of the momentum-dependent symmetry potential on the free neutron-to-proton ratio of pre-equilibrium nucleon emission. It is found that, for the 132Sn+124Sn reaction at 400 MeV/nucleon incident beam energy, the free n /p ratio of pre-equilibrium nucleon emission mainly probes the momentum dependence of the symmetry potential at a nucleon momentum around 400-600 MeV/c , whereas for 200 MeV/nucleon incident beam energy this observable mainly probes the momentum dependence of the symmetry potential at a nucleon momentum around 200-400 MeV/c . To probe the symmetry energy/potential using free n /p ratio, not all the details of the momentum dependence of the symmetry potential are important: the values of symmetry potential in only a certain momentum range are crucial for an observable. It is important to input reasonable density and momentum dependence of the symmetry potential according to the magnitude of incident beam energy of heavy-ion collisions. The present experimental data on the symmetry potential are not enough for probing the density-dependent symmetry energy. More experimental data (such as nucleon and nuclei scattering experiments at different nucleonic momenta and densities) on the symmetry potential are therefore needed to pin down the density-dependent symmetry energy.

  5. Systematic study of pre-equilibrium emission at low energies in 12C- and 16O-induced reactions

    NASA Astrophysics Data System (ADS)

    Sharma, Manoj Kumar; Singh, Pushendra P.; Singh, Devendra P.; Yadav, Abhishek; Sharma, Vijay Raj; Bala, Indu; Kumar, Rakesh; Unnati, Singh, B. P.; Prasad, R.

    2015-01-01

    Background: The role of pre-equilibrium emission within the heavy-ion fusion process has not been fully characterized. An accurate description of this process is important for understanding the formation of the compound nucleus in fusion reactions. Purpose: We develop a systematic description, based on experimental measurements, of the strength of the pre-equilibrium process in heavy-ion fusion reactions. Method: With a view to study pre-equilibrium emission process, the excitation functions for some neutron emission channels occurring in the fusion of 12C with 128Te and 169Tm, and of 16O with 159Tb,169Tm, and 181Ta, respectively, have been measured at incident energies from near the Coulomb barrier to ≈7 MeV/nucleon. The off-line γ -ray spectrometry-based activation technique has been used for the measurements of excitation functions. The measured excitation functions have been compared with theoretical predictions based on pure statistical model code pace4 and Geometry Dependent Hybrid (GDH)-based code alice-91. The strength of pre-equilibrium emission has also determined from comparison of the experimental excitation functions and the pace4 calculations. Results: The measured excitation functions are satisfactorily reproduced by the pace4 calculations in the energy region up to the peak position. However, at relatively higher energies, the enhancement of experimental cross sections in the tail portion of excitation functions as compared to the theoretical predictions of code pace4 has been observed. The observed deviation may be attributed to the pre-equilibrium emission of particles during the thermalization of the compound nucleus. Further, alice-91 calculations which include PE emission satisfactorily reproduce the experimental data even at higher energies, indicating the significant contribution of pre-equilibrium emissions. Conclusions: Analysis of data clearly indicates that pre-equilibrium emission is an important reaction mechanism even at low

  6. Evidence of Pre-Equilibrium {gamma}-Ray Emission in Heavy Ion Collisions at Intermediate Incident Energies

    SciTech Connect

    S. Tudisco; F. Amorini; G. Cardella; A. Di Pietro; P. Figuera; G. Lanzalone; A. Musumarra; M. Papa; G. Pappalardo; S. Pirrone; F. Rizzo

    1999-12-31

    The experimental results of {sup 40}Ca + {sup 48}Ca,{sup 40}Ca,{sup 46}Ti reactions are reported. The comparison between {gamma}-ray spectra measured in coincidence with fusion evaporation residues for the three colliding systems shows a clear evidence of pre-equilibrium {gamma}-rays emission in the region around 10 MeV. BNV simulations also predict this emission. The saturation of GDR strength with temperature has been found with some dependence on the colliding system.

  7. Evidence of pre-equilibrium {gamma}-ray emission in heavy ion collisions at intermediate incident energies

    SciTech Connect

    Tudisco, S.; Di Pietro, A.; Pappalardo, G.; Rizzo, F.; Amorini, F.; Cardella, G.; Papa, M.; Figuera, P.; Musumarra, A.; Lanzalone, G.; Pirrone, S.

    1999-11-16

    The experimental results of {sup 40}Ca+{sup 48}Ca,{sup 40}Ca,{sup 46}Ti reactions are reported. The comparison between {gamma}-ray spectra measured in coincidence with fusion evaporation residues for the three colliding systems shows a clear evidence of pre-equilibrium {gamma}-rays emission in the region around 10 MeV. BNV simulations also predict this emission. The saturation of GDR strength with temperature has been found with some dependence on the colliding system.

  8. The Equilibrium and Pre-equilibrium Triton Emission Spectra of Some Target Nuclei for ( n, xt) Reactions up to 45 MeV Energy

    NASA Astrophysics Data System (ADS)

    Tel, E.; Kaplan, A.; Aydın, A.; Özkorucuklu, S.; Büyükuslu, H.; Yıldırım, G.

    2010-08-01

    Although there have been significant research and development studies on the inertial and magnetic fusion reactor technology, there is still a long way to go to penetrate commercial fusion reactors to the energy market. Tritium self-sufficiency must be maintained for a commercial power plant. For self-sustaining (D-T) fusion driver tritium breeding ratio should be greater than 1.05. So, working out the systematics of ( n,t) reaction cross sections and triton emission differential data are important for the given reaction taking place on various nuclei at different energies. In this study, ( n,xt) reactions for some target nuclei as 16O, 27Al, 59Co and 209Bi have been investigated up to 45 MeV incident neutron energy. In the calculations of the triton emission spectra, the pre-equilibrium and equilibrium effects have been used. The calculated results have been compared with the experimental data taken from the literature.

  9. Exclusive Multiple Emission Cross Sections in the Hybrid Monte Carlo Pre-equilibrium Model and in EMPIRE-3.1

    NASA Astrophysics Data System (ADS)

    Carlson, B. V.; Brito, L.; Mega, D. F.; Capote, R.; Herman, M.; Rego, M. E.

    2014-04-01

    We discuss the general concept of exclusive emission cross sections and spectra and the exclusive spectra of the ENDF library. We briefly review the exclusive hybrid Monte Carlo simulation model and show how its exclusive cross sections can be integrated into the reaction code EMPIRE-3.1. We close by discussing several examples.

  10. Matching pre-equilibrium dynamics and viscous hydrodynamics

    SciTech Connect

    Martinez, Mauricio; Strickland, Michael

    2010-02-15

    We demonstrate how to match pre-equilibrium dynamics of a 0+1-dimensional quark-gluon plasma to second-order viscous hydrodynamical evolution. The matching allows us to specify the initial values of the energy density and shear tensor at the initial time of hydrodynamical evolution as a function of the lifetime of the pre-equilibrium period. We compare two models for pre-equilibrium quark-gluon plasma, longitudinal free streaming and collisionally broadened longitudinal expansion, and present analytic formulas that can be used to fix the necessary components of the energy-momentum tensor. The resulting dynamical models can be used to assess the effect of pre-equilibrium dynamics on quark-gluon plasma observables. Additionally, we investigate the dependence of entropy production on pre-equilibrium dynamics and discuss the limitations of the standard definitions of nonequilibrium entropy.

  11. Heavy ion collisions and the pre-equilibrium exciton model

    SciTech Connect

    Betak, E.

    2012-10-20

    We present a feasible way to apply the pre-equilibrium exciton model in its masterequation formulation to heavy-ion induced reactions including spin variables. Emission of nucleons, {gamma}'s and also light clusters is included in our model.

  12. Pre-equilibrium studies in monoisotopic praseodymium

    SciTech Connect

    Singh, B.P.; Mustafa, M.M.; Sankarcharyulu, M.G.V.

    1994-12-31

    Measurement and analysis of excitation functions in {alpha}-induced reactions has become an important tool for studying the pre-equilibrium (PE) phenomenon. As part of the programme of precise measurement and analysis of excitation functions in reactions for a large number of nuclei, the authors report the measurement of excitation functions for the reactions {sup 141}Pr({alpha},n){sup 144}Pm and {sup 141}Pr({alpha},2n){sup 143}Pm in the energy range from threshold to {approx}40 MeV. To the best of their knowledge, these excitation functions have been measured for the first time. Measurements have been performed using stacked foil activation technique. The irradiation has been carried out at the Variable Energy Cyclotron Centre (VECC), Calcutta, India using the {alpha}-beam of {approx} 40 MeV. The post irradiation analysis has been done using the HPGe detector coupled to the ORTEC`s PC based multichannel analyser. The analysis of the excitation functions has been carried out using the semi-classical computer codes ACT and ALICE-82. These codes use Hauser-Feshbach/ Welsskopf-Ewing formalism for compound nucleus calculations and exciton/hybrid model for simulating PE contributions. The quantum mechanical statistical multistep code EXIFON has also been used for the analysis of these excitation functions. The comparison of results with different codes will be presented.

  13. Pre-equilibrium dilepton production from an anisotropic quark-gluon plasma

    SciTech Connect

    Martinez, Mauricio; Strickland, Michael

    2008-09-15

    We calculate leading-order dilepton yields from a quark-gluon plasma that has a time-dependent anisotropy in momentum space. Such anisotropies can arise during the earliest stages of quark-gluon plasma evolution due to the rapid longitudinal expansion of the created matter. Two phenomenological models for the proper-time dependence of the parton hard momentum scale, p{sub hard}, and the plasma anisotropy parameter, {xi}, are constructed that describe the transition of the plasma from its initial nonequilibrium state to an isotropic thermalized state. The first model constructed interpolates between 1+1 dimensional free streaming at early times and 1+1 dimensional ideal hydrodynamical expansion at late times. In the second model we include the effect of collisional broadening of the parton distribution functions in the early-time pre-equilibrium stage of plasma evolution. We find for both cases that for fixed initial conditions high-energy dilepton production is enhanced by pre-equilibrium emission. When the models are constrained to fixed final pion multiplicity the dependence of the resulting spectra on the assumed plasma isotropization time is reduced. Using our most realistic collisionally broadened model we find that high-transverse-momentum dilepton production would be enhanced by at most 40% at the Relativistic Heavy Ion Collider and 50% at the CERN Large Hadron Collider if one assumes an isotropization/thermalization time of 2 fm/c. Given sufficiently precise experimental data this enhancement could be used to determine the plasma isotropization time experimentally.

  14. Pre-equilibrium dynamics and heavy-ion observables

    NASA Astrophysics Data System (ADS)

    Heinz, Ulrich; Liu, Jia

    2016-12-01

    To bracket the importance of the pre-equilibrium stage on relativistic heavy-ion collision observables, we compare simulations where it is modeled by either free-streaming partons or fluid dynamics. These cases implement the assumptions of extremely weak vs. extremely strong coupling in the initial collision stage. Accounting for flow generated in the pre-equilibrium stage, we study the sensitivity of radial, elliptic and triangular flow on the switching time when the hydrodynamic description becomes valid. Using the hybrid code iEBE-VISHNU [C. Shen, Z. Qiu, H. Song, J. Bernhard, S. Bass and U. Heinz, Comput. Phys. Commun. 199 (2016) 61] we perform a multi-parameter search, constrained by particle ratios, integrated elliptic and triangular charged hadron flow, the mean transverse momenta of pions, kaons and protons, and the second moment < pT2 > of the proton transverse momentum spectrum, to identify optimized values for the switching time τs from pre-equilibrium to hydrodynamics, the specific shear viscosity η / s, the normalization factor of the temperature-dependent specific bulk viscosity (ζ / s) (T), and the switching temperature Tsw from viscous hydrodynamics to the hadron cascade UrQMD. With the optimized parameters, we predict and compare with experiment the pT-distributions of π, K, p, Λ, Ξ and Ω yields and their elliptic flow coefficients, focusing specifically on the mass-ordering of the elliptic flow for protons and Lambda hyperons which is incorrectly described by VISHNU without pre-equilibrium flow.

  15. PHASE-OTI: A pre-equilibrium model code for nuclear reactions calculations

    NASA Astrophysics Data System (ADS)

    Elmaghraby, Elsayed K.

    2009-09-01

    The present work focuses on a pre-equilibrium nuclear reaction code (based on the one, two and infinity hypothesis of pre-equilibrium nuclear reactions). In the PHASE-OTI code, pre-equilibrium decays are assumed to be single nucleon emissions, and the statistical probabilities come from the independence of nuclei decay. The code has proved to be a good tool to provide predictions of energy-differential cross sections. The probability of emission was calculated statistically using bases of hybrid model and exciton model. However, more precise depletion factors were used in the calculations. The present calculations were restricted to nucleon-nucleon interactions and one nucleon emission. Program summaryProgram title: PHASE-OTI Catalogue identifier: AEDN_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEDN_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 5858 No. of bytes in distributed program, including test data, etc.: 149 405 Distribution format: tar.gz Programming language: Fortran 77 Computer: Pentium 4 and Centrino Duo Operating system: MS Windows RAM: 128 MB Classification: 17.12 Nature of problem: Calculation of the differential cross section for nucleon induced nuclear reaction in the framework of pre-equilibrium emission model. Solution method: Single neutron emission was treated by assuming occurrence of the reaction in successive steps. Each step is called phase because of the phase transition nature of the theory. The probability of emission was calculated statistically using bases of hybrid model [1] and exciton model [2]. However, more precise depletion factor was used in the calculations. Exciton configuration used in the code is that described in earlier work [3]. Restrictions: The program is restricted to single nucleon emission and nucleon

  16. Calibration of pre-equilibrium HF-LPME and its application to the rapid determination of free analytes in biological fluids.

    PubMed

    Xu, Baiqiu; Chen, Min; Hou, Jinxing; Chen, Xi; Zhang, Xu; Cui, Shufen

    2015-02-01

    This study establishes a novel calibration method for pre-equilibrium hollow-fiber liquid-phase microextraction (PE-HF-LPME), where the time constant of the extraction of the analyte from sample matrix to the extraction phase (organic solvent) is obtained from a simple concentration curve. Comparing to the traditional kinetic calibration method, where the time constant was obtained from the extraction time profile, the new calibration approach shows improved accuracy and precision. More importantly, deuterated standards are not required in the new method, thus significantly improving its cost-effectiveness and extending its applicability to a wide range of analytes lack of deuterated analogs serving as internal standards. In addition, mass spectrometry is not necessary for the quantification of analytes with the new calibration method, which may further extend the applicability of PE-HF-LPME to some laboratories without mass spectrometers. This study has been substantiated with both theoretical and experimental evidences. Further, the feasibility of the method for real biological samples was demonstrated by measuring the free concentration of flunitrazepam in urine and plasma samples and its drug-protein binding ratio in plasma. The results showed that the method had a short analysis time and was easily implemented with high accuracy and good reproducibility.

  17. Stratospheric emissions effects database development

    NASA Technical Reports Server (NTRS)

    Baughcum, Steven L.; Henderson, Stephen C.; Hertel, Peter S.; Maggiora, Debra R.; Oncina, Carlos A.

    1994-01-01

    This report describes the development of a stratospheric emissions effects database (SEED) of aircraft fuel burn and emissions from projected Year 2015 subsonic aircraft fleets and from projected fleets of high-speed civil transports (HSCT's). This report also describes the development of a similar database of emissions from Year 1990 scheduled commercial passenger airline and air cargo traffic. The objective of this work was to initiate, develop, and maintain an engineering database for use by atmospheric scientists conducting the Atmospheric Effects of Stratospheric Aircraft (AESA) modeling studies. Fuel burn and emissions of nitrogen oxides (NO(x) as NO2), carbon monoxide, and hydrocarbons (as CH4) have been calculated on a 1-degree latitude x 1-degree longitude x 1-kilometer altitude grid and delivered to NASA as electronic files. This report describes the assumptions and methodology for the calculations and summarizes the results of these calculations.

  18. Excitation functions of heavy residues produced in the 14N+103Rh reaction up to 400 MeV: Analysis of the pre-equilibrium mechanism with the hybrid Monte Carlo simulation model

    NASA Astrophysics Data System (ADS)

    Acharya, J.; Mukherjee, S.; Steyn, G. F.; Singh, N. L.; Chatterjee, A.

    2016-02-01

    The excitation functions of heavy residues, produced in the interaction of 14N with 103Rh, have been measured over the projectile energy region from a threshold up to 400 MeV by means of the activation method in conjunction with γ-ray spectroscopy. Cross sections for 15 reaction residues are presented, namely, 104Cd, Ag-105103, Pd-10199, 97,99,101Rh, Ru,9795, and Tc-9694. The experimental data are compared with theoretical model predictions using the hybrid Monte Carlo simulation model as implemented in the recently released alice2014 code. The theory assumes that the dominant pre-equilibrium mechanism includes multinucleon and cluster emissions in the initial stages of the interaction between the projectile and the target nucleus. Overall, the theoretical predictions provide a satisfactory agreement with the trend of the present experimental results for most of the observed reaction residues. This provides strong evidence that the underlying reaction mechanisms in the code are appropriately described. Overall, the Obninsk level densities give the best results in the present study.

  19. Effects of fuel variables on diesel emissions

    SciTech Connect

    Baines, T.M.; Somers, J.H.; Hellman, K.H.

    1982-08-01

    Recent data obtained by EPA on identification and quantification of different emissions (i.e., characterization) from a variety of diesel engines is summarized. Extensive work has been done comparing emissions from some light duty diesel and gasoline passenger cars. The work on the diesel vehicles was expanded to include tests with five different diesel fuels to determine how fuel composition affects emissions. This work showed that use of a poorer quality fuel frequently made emissions worse. The investigation of fuel composition continued with a project in which specific fuel parameters were systematically varied to determine their effect on emissions. EPA is presently testing a variety of fuels derived from coal and oil shale to determine their effects on emissions. EPA has also tested a heavy duty Volvo diesel bus engine designed to run on methanol and diesel fuel, each injected through its own injection system. The use of the dual fuel resulted in a reduction in particlates and NO/sub x/ but an increase in HC and CO compared to a baseline Volvo diesel engine running on pure diesel fuel. Finally, some Ames bioassay tests have been performed on samples from the diesel passenger cars operated on various fuels and blends. An increase in Ames test response (mutagenicity) was seen when the higher aromatic blend was used and also when a commercial cetane improver was used. Samples from the Volvo diesel bus engine fueled with methanol and diesel fuel showed that use of a catalyst increased the Ames response.

  20. Gunn effect in field-emission phenomena

    NASA Astrophysics Data System (ADS)

    Litovchenko, V.; Evtukh, A.; Yilmazoglu, O.; Mutamba, K.; Hartnagel, H. L.; Pavlidis, D.

    2005-02-01

    The peculiarities of electron field emission from nanostructured GaN surface have been investigated. The current-voltage characteristics of emission current in Fowler-Nordheim plot show two parts with different slopes. There are emission current oscillations in the changing slope region. As an explanation for the experimental results a model based on the electron-emission analysis from lower (Γ) valley, upper (U) valley, and electron transition between valleys due to heating in electric field has been proposed. The electron affinities for the emission from Γ and U valleys have been determined. The decreased affinities from there valleys have been estimated for quantization in nanostructured GaN.

  1. Emission effects of memory in rocks

    NASA Astrophysics Data System (ADS)

    Rzhevskiy, V. V.; Yamshchikov, V. S.; Shkuratnik, V. L.; Lykov, K. G.; Farafonov, V. M.

    1984-05-01

    Development of the destruction process in rocks results in an increase in the activity and level of acoustic emission (AE) and electromagnetic radiation (EMR). These acoustic and effects accompanying the cyclic loading of marble and silvinite-carnallite salts were investigated. In the case of salt, the increase in loading can result in a monotonic increase in AE and EMR, whereas for marble AE and EMR are manifested in the form of individual bursts whose level exceeds the background level by a factor of 2-10. In a loading regime, the times of appearance of EMR and AE impulses coincide, but the activity of the latter is greater. With the second loading up to the maximum load in the first cycle, the AE level is approximately an order of magnitude less than in the preceding cycle, whereas the EMR level is commensurable with the EM background. The phenomena observed should play an important role in recognizing the fundamental relationship between the dynamics of deformation of rocks and their electric properties and also in establishing the physical nature and methods for using the memory of rocks in investigation of their stressed state, in earthquake prediction and in studying dynamic processes in a rock mass.

  2. The immediate environmental effects of tephra emission

    NASA Astrophysics Data System (ADS)

    Ayris, Paul Martin; Delmelle, Pierre

    2012-11-01

    The Earth's history is punctuated by large explosive eruptions that eject large quantities of magma and silicate rock fragments into the atmosphere. These tephra particles can sometimes be dispersed across millions of square kilometres or even entire continents. The interaction of tephra with or in receiving environments may induce an array of physical, chemical and biological effects. The consequences for affected systems and any dependent communities may be chronic and localised in the event of frequent, small eruptions, while larger and rarer events may have acute, regional-scale impacts. It is, therefore, necessary to document the range of possible impacts that tephra may induce in receiving environments and any resulting effects in interconnected systems. We collate results from many studies to offer a detailed multidisciplinary and interdisciplinary review of the immediate post-eruptive effects of tephra emission into the atmosphere, onto vegetation, soil or ice/snow surfaces and in aquatic systems. We further consider the repercussions that may be induced in the weeks to years afterwards. In the atmosphere, tephra can influence cloud properties and air chemistry by acting as ice nuclei (IN) or by offering sites for heterogeneous reactions, respectively. Tephra on vegetation causes physical damage, and sustained coverage may elicit longer-term physiological responses. Tephra deposits on soils may alter their capacity to exchange gas, water and heat with the atmosphere or may have a specific chemical effect, such as nutrient input or acidification, on sensitive soils. Tephra deposition onto snow or ice may affect ablation rates. Rivers and lakes may experience turbidity increases and changes in their morphology as a result of fallout and prolonged (months or years) erosion from the tephra-covered catchment. In the first weeks after deposition, tephra leaching may affect river chemistry. The abundance and speciation of phytoplankton populations in lakes may be

  3. WEATHER EFFECTS ON ISOPRENE EMISSION CAPACITY AND APPLICATIONS IN EMISSIONS ALGORITHMS

    EPA Science Inventory

    Many plants synthesize isoprene. Because it is volatile and reacts rapidly with hydroxyl radicals, it is emitted to the atmosphere and plays a critical role in atmospheric chemistry. Determining effective remediation efforts for ozone pollution requires accurate isoprene emission...

  4. Health effects of inhaled gasoline engine emissions.

    PubMed

    McDonald, Jacob D; Reed, Matthew D; Campen, Matthew J; Barrett, Edward G; Seagrave, JeanClare; Mauderly, Joe L

    2007-01-01

    Despite their prevalence in the environment, and the myriad studies that have shown associations between morbidity or mortality with proximity to roadways (proxy for motor vehicle exposures), relatively little is known about the toxicity of gasoline engine emissions (GEE). We review the studies conducted on GEE to date, and summarize the findings from each of these studies. While there have been several studies, most of the studies were conducted prior to 1980 and thus were not conducted with contemporary engines, fuels, and driving cycles. In addition, many of the biological assays conducted during those studies did not include many of the assays that are conducted on contemporary inhalation exposures to air pollutants, including cardiovascular responses and others. None of the exposures from these earlier studies were characterized at the level of detail that would be considered adequate today. A recent GEE study was conducted as part of the National Environmental Respiratory Center (www.nercenter.org). In this study several in-use mid-mileage General Motors (Chevrolet S-10) vehicles were purchased and utilized for inhalation exposures. An exposure protocol was developed where engines were operated with a repeating California Unified Driving Cycle with one cold start per day. Two separate engines were used to provide two cold starts over a 6-h inhalation period. The exposure atmospheres were characterized in detail, including detailed chemical and physical analysis of the gas, vapor, and particle phase. Multiple rodent biological models were studied, including general toxicity and inflammation (e.g., serum chemistry, lung lavage cell counts/differentials, cytokine/chemokine analysis, histopathology), asthma (adult and in utero exposures with pulmonary function and biochemical analysis), cardiovascular effects (biochemical and electrocardiograph changes in susceptible rodent models), and susceptibility to infection (Pseudomonas bacteria challenge). GEE resulted in

  5. Tamm State-Coupled Emission: Effect of Probe Location and Emission Wavelength

    PubMed Central

    2015-01-01

    We report the effect of the probe location and wavelength on the emission spatial distribution and spectral properties of fluorophores located on structures which display Tamm states. Our structure consists of a one-dimensional photonic crystal (1DPC)—that is, a multilayer structure of alternate high and low refractive index dielectrics—and a thin top silver film. Simulations show the presence of Tamm and surface plasmon modes in the structure. The electric field intensities for the Tamm modes are located mostly in the dielectric layer below the metal film. The corresponding field intensities for the surface plamon modes are located above the metal film in the distal side. Tamm states can be in resonance with the incident light normal or near normal to the surface, within the light line, and can be accessed without the use of a coupling prism or gratings. We investigated the emission spectra and angular distribution of the emission for probes located above and below the metal film to explore the interaction of fluorophores with Tamm plasmons and surface plasmons modes. Three probes were chosen with different overlap of the emission spectra with the Tamm modes. The fluorophores below the metal film coupled predominantly with the Tamm state and displayed more intense and only Tamm state-coupled emission (TSCE). Probes above the metal film display both surface plasmon-coupled emission (SPCE) and Tamm state-coupled emission. In contrast to SPCE, which shows only KR, P-polarized emission, the Tamm states can display both S- and P-polarized emission and can be populated using both RK and KR illuminations. The TSCE angle is highly sensitive to wavelength, which suggests the use of Tamm structures to provide both directional emission and wavelength dispersion. The combination of plasmonic and photonic structures with directional emission close to surface normal offers the opportunities for new design formats for clinical testing, portable devices, and other

  6. Subsurface Emission Effects in AMSR-E Measurements: Implications for Land Surface Microwave Emissivity Retrieval

    NASA Technical Reports Server (NTRS)

    Galantowicz, John F.; Moncet, Jean-Luc; Liang, Pan; Lipton, Alan E.; Uymin, Gennady; Prigent, Catherine; Grassotti, Christopher

    2011-01-01

    An analysis of land surface microwave emission time series shows that the characteristic diurnal signature associated with subsurface emission in sandy deserts carry over to arid and semi-arid region worldwide. Prior work found that diurnal variation of Special Sensor Microwave/Imager (SSM/I) brightness temperatures in deserts was small relative to International Satellite Cloud Climatology Project land surface temperature (LST) variation and that the difference varied with surface type and was largest in sand sea regions. Here we find more widespread subsurface emission effects in Advanced Microwave Scanning Radiometer-EOS (AMSR-E) measurements. The AMSR-E orbit has equator crossing times near 01:30 and 13 :30 local time, resulting in sampling when near-surface temperature gradients are likely to be large and amplifying the influence of emission depth on effective emitting temperature relative to other factors. AMSR-E measurements are also temporally coincident with Moderate Resolution Imaging Spectroradiometer (MODIS) LST measurements, eliminating time lag as a source of LST uncertainty and reducing LST errors due to undetected clouds. This paper presents monthly global emissivity and emission depth index retrievals for 2003 at 11, 19, 37, and 89 GHz from AMSR-E, MODIS, and SSM/I time series data. Retrieval model fit error, stability, self-consistency, and land surface modeling results provide evidence for the validity of the subsurface emission hypothesis and the retrieval approach. An analysis of emission depth index, emissivity, precipitation, and vegetation index seasonal trends in northern and southern Africa suggests that changes in the emission depth index may be tied to changes in land surface moisture and vegetation conditions

  7. Shunting effect in explosive electron emission

    NASA Astrophysics Data System (ADS)

    Mesyats, G. A.; Parkevich, E. V.; Pikuz, S. A.; Yalandin, M. I.

    2016-10-01

    An explanation is given to the results of an experiment on studying the explosive electron emission in a wire-cathode diode where a strongly nonuniform energy deposition into the wire material was observed using an X pinch as a radiation source for projection x-ray imaging. The specific input energy, contrary to the well-known observations, was not a maximum at the wire end, i.e., in the region of the strongest electric field, and the wire explosion occurred in the bulk, distant from the end. This is accounted for by the contribution of the wire side surface to explosive electron emission and by the gas desorption from the wire intensely heated by a current of density 108 A/cm2. Thus, the space between anode and cathode (wire end) is bridged by two plasmas: one generated due to the explosive electron emission from the wire side surface and the other produced from the desorbed gas.

  8. Spontaneous emission and nonlinear effects in photonic bandgap materials

    NASA Astrophysics Data System (ADS)

    Fogel, Ishella S.; Bendickson, Jon M.; Tocci, Michael D.; Bloemer, Mark J.; Scalora, Michael; Bowden, Charles M.; Dowling, Jonathan P.

    1998-03-01

    We summarize and review our theoretical and experimental work on spontaneous emission and nonlinear effects in one-dimensional, photonic bandgap (PBG) structures. We present a new result: a method for calculating the normal-mode solutions - and hence the spontaneous emission of embedded emitters - in an arbitrary, linear, lossless, one-dimensional, PBG structure.

  9. [Effects of rice plants on methane emission from paddy fields].

    PubMed

    Jia, Zhongjun; Cai, Zucong

    2003-11-01

    Methane emission from rice paddy fields is the net result of the combination of many processes, i.e., CH4 production, CH4 oxidation and CH4 transportation in paddy soil. Rice plants play a key role in the CH4 emission from paddy fields, particularly in all the processes involved. The positive and negative effects of rice plants on CH4 emission from paddy fields are well recognized as the main factors influencing the temporal variation of CH4 emission flux in paddy field. Process-based studies about the effects of rice plants on methane emission from paddy fields were summarized, and different roles of rice plants on this emission were discussed. Root exudates and litters of rice plants could serve as the substrate for methanogenesis and enhance the CH4 production of paddy soils, resulting in a high CH4 emission peak, particularly in rice late growing season. Rhizospheric CH4 oxidation induced by rice root-excreted oxygen constitutes a main biogenic sink of CH4, which could account for 36-90% of CH4 produced in paddy soil over the entire growing season of rice. Up to 80% and more of CH4 released from rice field during a growing season could be emitted by rice plant-mediated transport. The fully developed aerenchyma of rice plants could be of importance in CH4 emission during rice growing seasons, and responsible for the CH4 emission peak observed at rice early growing season.

  10. The effect of two ammonia-emission-reducing pig housing systems on odour emission.

    PubMed

    Mol, G; Ogink, N W M

    2004-01-01

    Odour nuisance from agricultural activities is increasing in densely populated countries like the Netherlands. To develop adequate regulations, a large-scale, government-financed monitoring programme was started in the mid-1990s to establish odour emission levels for both conventional and low ammonia emission housing systems for cattle, pigs and poultry. The results indicate that high- and low-odour emission housing are difficult to distinguish because of the large variation within housing systems. Measurements on different farm locations within the same housing system show both a large variation between locations and within one location (in time). The latter, however, is significantly smaller, which suggests that farm management is an important determinant in odour emission that interferes with the effects of housing systems. The current research was aimed at determining the effect of two common ammonia-reducing pig-housing systems on odour emissions compared to conventional housing systems under similar management conditions. The respective reduction principles of these systems are reducing the emitting surface of the manure pit and cooling of manure in the manure pit (both pits beneath slatted floor). Five farms that combined conventional housing with one low-ammonia system (three reduced emitting surface and two manure cooling) were selected for a direct, pair-wise comparison of (olfactometric) odour emission measurements. The results show a highly significant effect (p < 0.01) for two of the three reduced emitting surface systems and for one of the two manure cooling system. The average odour reduction percentages of these systems are 35% (from 24.9 to 16.0 OUE/s per animal) and 23% (from 30.1 to 24.0 OUE/s per animal) respectively. Although odour emission reduction through the type of housing system is possible, management factors interact with the system and thereby determine whether the system reduces odour emission or not.

  11. Evaluating the Effects of Emission Reductions on Multiple Pollutants Simultaneously

    EPA Science Inventory

    Modeling studies over the Philadelphia metropolitan area have examined how emission control strategies might affect several types of air pollutants simultaneously. This study supports considering effects of multiple pollutants in determining optimum pollution control strategies. ...

  12. Effects of electron emission on sheath potential

    NASA Astrophysics Data System (ADS)

    Dow, Ansel; Khrabrov, Alexander; Kaganovich, Igor; Schamis, Hanna

    2015-11-01

    We investigate the potential profile of a sheath under the influence of surface electron emission. The plasma and sheath profiles are simulated using the Large Scale Plasma (LSP) particle-in-cell code. Using one dimensional models we corroborate the analytical relationship between sheath potential and plasma electron and emitted electron temperatures derived earlier. This work was made possible by funding from the Department of Energy for the Summer Undergraduate Laboratory Internship (SULI) program. This work is supported by the US DOE Contract No. DE-AC02-09CH11466.

  13. The difference between laboratory and in-situ pixel-averaged emissivity: The effects on temperature-emissivity separation

    NASA Technical Reports Server (NTRS)

    Matsunaga, Tsuneo

    1993-01-01

    Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a Japanese future imaging sensor which has five channels in thermal infrared (TIR) region. To extract spectral emissivity information from ASTER and/or TIMS data, various temperature-emissivity (T-E) separation methods have been developed to date. Most of them require assumptions on surface emissivity, in which emissivity measured in a laboratory is often used instead of in-situ pixel-averaged emissivity. But if these two emissivities are different, accuracies of separated emissivity and surface temperature are reduced. In this study, the difference between laboratory and in-situ pixel-averaged emissivity and its effect on T-E separation are discussed. TIMS data of an area containing both rocks and vegetation were also processed to retrieve emissivity spectra using two T-E separation methods.

  14. Modeling electron emission and surface effects from diamond cathodes

    SciTech Connect

    Dimitrov, D. A.; Smithe, D.; Cary, J. R.; Ben-Zvi, I.; Rao, T.; Smedley, J.; Wang, E.

    2015-02-05

    We developed modeling capabilities, within the Vorpal particle-in-cell code, for three-dimensional (3D) simulations of surface effects and electron emission from semiconductor photocathodes. They include calculation of emission probabilities using general, piece-wise continuous, space-time dependent surface potentials, effective mass and band bending field effects. We applied these models, in combination with previously implemented capabilities for modeling charge generation and transport in diamond, to investigate the emission dependence on applied electric field in the range from approximately 2 MV/m to 17 MV/m along the [100] direction. The simulation results were compared to experimental data. For the considered parameter regime, conservation of transverse electron momentum (in the plane of the emission surface) allows direct emission from only two (parallel to [100]) of the six equivalent lowest conduction band valleys. When the electron affinity χ is the only parameter varied in the simulations, the value χ = 0.31 eV leads to overall qualitative agreement with the probability of emission deduced from experiments. Including band bending in the simulations improves the agreement with the experimental data, particularly at low applied fields, but not significantly. In this study, using surface potentials with different profiles further allows us to investigate the emission as a function of potential barrier height, width, and vacuum level position. However, adding surface patches with different levels of hydrogenation, modeled with position-dependent electron affinity, leads to the closest agreement with the experimental data.

  15. Modeling electron emission and surface effects from diamond cathodes

    DOE PAGES

    Dimitrov, D. A.; Smithe, D.; Cary, J. R.; ...

    2015-02-05

    We developed modeling capabilities, within the Vorpal particle-in-cell code, for three-dimensional (3D) simulations of surface effects and electron emission from semiconductor photocathodes. They include calculation of emission probabilities using general, piece-wise continuous, space-time dependent surface potentials, effective mass and band bending field effects. We applied these models, in combination with previously implemented capabilities for modeling charge generation and transport in diamond, to investigate the emission dependence on applied electric field in the range from approximately 2 MV/m to 17 MV/m along the [100] direction. The simulation results were compared to experimental data. For the considered parameter regime, conservation of transversemore » electron momentum (in the plane of the emission surface) allows direct emission from only two (parallel to [100]) of the six equivalent lowest conduction band valleys. When the electron affinity χ is the only parameter varied in the simulations, the value χ = 0.31 eV leads to overall qualitative agreement with the probability of emission deduced from experiments. Including band bending in the simulations improves the agreement with the experimental data, particularly at low applied fields, but not significantly. In this study, using surface potentials with different profiles further allows us to investigate the emission as a function of potential barrier height, width, and vacuum level position. However, adding surface patches with different levels of hydrogenation, modeled with position-dependent electron affinity, leads to the closest agreement with the experimental data.« less

  16. Modeling electron emission and surface effects from diamond cathodes

    SciTech Connect

    Dimitrov, D. A.; Smithe, D.; Cary, J. R.; Ben-Zvi, I.; Rao, T.; Smedley, J.; Wang, E.

    2015-02-07

    We developed modeling capabilities, within the Vorpal particle-in-cell code, for three-dimensional simulations of surface effects and electron emission from semiconductor photocathodes. They include calculation of emission probabilities using general, piece-wise continuous, space-time dependent surface potentials, effective mass, and band bending field effects. We applied these models, in combination with previously implemented capabilities for modeling charge generation and transport in diamond, to investigate the emission dependence on applied electric field in the range from approximately 2 MV/m to 17 MV/m along the [100] direction. The simulation results were compared to experimental data. For the considered parameter regime, conservation of transverse electron momentum (in the plane of the emission surface) allows direct emission from only two (parallel to [100]) of the six equivalent lowest conduction band valleys. When the electron affinity χ is the only parameter varied in the simulations, the value χ = 0.31 eV leads to overall qualitative agreement with the probability of emission deduced from experiments. Including band bending in the simulations improves the agreement with the experimental data, particularly at low applied fields, but not significantly. Using surface potentials with different profiles further allows us to investigate the emission as a function of potential barrier height, width, and vacuum level position. However, adding surface patches with different levels of hydrogenation, modeled with position-dependent electron affinity, leads to the closest agreement with the experimental data.

  17. Pre-equilibrium parton dynamics: Proceedings

    SciTech Connect

    Wang, Xin-Nian

    1993-12-31

    This report contains papers on the following topics: parton production and evolution; QCD transport theory; interference in the medium; QCD and phase transition; and future heavy ion experiments. This papers have been indexed separately elsewhere on the data base.

  18. Effect of low emission sources on air quality in Cracow

    SciTech Connect

    Nedoma, J.

    1995-12-31

    The paper presents calculation of power engineering low emission and results of stimulation of the effect of this emission on air quality in Cracow, Poland. It has been stated that the segment of low emission in central areas of the town makes up ca. 40% of the observed concentration of sulfur dioxide. Furthermore it has been stated that the capital investment must be concentrated in the central part of the town in order to reach noticeable improvement of air quality in Cracow. Neither the output of a separate power source nor the emission level and its individual harmful effect, but the location of the source and especially packing density of the sources must decide the priority of upgrading actions.

  19. Effect of Vehicle Characteristics on Unpaved Road Dust Emissions

    DTIC Science & Technology

    2005-01-01

    monitoring system is shown in Fig. 1. Each downwind tower was instrumented with four DustTraks (Model 8520, TSI Inc., St. Paul , MN) configured to measure... Pitchford , M., 2003a. Vehicle based road dust emissions measurement (III): effect of speed, traffic volume, location, and season on PM10 road dust emissions...Atmospheric Environment 37, 4583–4593. Etyemezian, V., Kuhns, H., Gillies, J., Green, M., Pitchford , M., Watson, J., 2003b. Vehicle based road dust

  20. Cost-effectiveness of reducing sulfur emissions from ships.

    PubMed

    Wang, Chengfeng; Corbett, James J; Winebrake, James J

    2007-12-15

    We model cost-effectiveness of control strategies for reducing SO2 emissions from U.S. foreign commerce ships traveling in existing European or hypothetical U.S. West Coast SO(x) Emission Control Areas (SECAs) under international maritime regulations. Variation among marginal costs of control for individual ships choosing between fuel-switching and aftertreatment reveals cost-saving potential of economic incentive instruments. Compared to regulations prescribing low sulfur fuels, a performance-based policy can save up to $260 million for these ships with 80% more emission reductions than required because least-cost options on some individual ships outperform standards. Optimal simulation of a market-based SO2 control policy for approximately 4,700 U.S. foreign commerce ships traveling in the SECAs in 2002 shows that SECA emissions control targets can be achieved by scrubbing exhaust gas of one out of ten ships with annual savings up to $480 million over performance-based policy. A market-based policy could save the fleet approximately $63 million annually under our best-estimate scenario. Spatial evaluation of ship emissions reductions shows that market-based instruments can reduce more SO2 closer to land while being more cost-effective for the fleet. Results suggest that combining performance requirements with market-based instruments can most effectively control SO2 emissions from ships.

  1. Effects of preprocessing method on TVOC emission of car mat

    NASA Astrophysics Data System (ADS)

    Wang, Min; Jia, Li

    2013-02-01

    The effects of the mat preprocessing method on total volatile organic compounds (TVOC) emission of car mat are studied in this paper. An appropriate TVOC emission period for car mat is suggested. The emission factors for total volatile organic compounds from three kinds of new car mats are discussed. The car mats are preprocessed by washing, baking and ventilation. When car mats are preprocessed by washing, the TVOC emission for all samples tested are lower than that preprocessed in other methods. The TVOC emission is in stable situation for a minimum of 4 days. The TVOC emitted from some samples may exceed 2500μg/kg. But the TVOC emitted from washed Polyamide (PA) and wool mat is less than 2500μg/kg. The emission factors of total volatile organic compounds (TVOC) are experimentally investigated in the case of different preprocessing methods. The air temperature in environment chamber and the water temperature for washing are important factors influencing on emission of car mats.

  2. Surface Emissivity Effects on Thermodynamic Retrieval of IR Spectral Radiance

    NASA Technical Reports Server (NTRS)

    Zhou, Daniel K.; Larar, Allen M.; Smith, William L.; Liu, Xu

    2006-01-01

    The surface emissivity effect on the thermodynamic parameters (e.g., the surface skin temperature, atmospheric temperature, and moisture) retrieved from satellite infrared (IR) spectral radiance is studied. Simulation analysis demonstrates that surface emissivity plays an important role in retrieval of surface skin temperature and terrestrial boundary layer (TBL) moisture. NAST-I ultraspectral data collected during the CLAMS field campaign are used to retrieve thermodynamic properties of the atmosphere and surface. The retrievals are then validated by coincident in-situ measurements, such as sea surface temperature, radiosonde temperature and moisture profiles. Retrieved surface emissivity is also validated by that computed from the observed radiance and calculated emissions based on the retrievals of surface temperature and atmospheric profiles. In addition, retrieved surface skin temperature and emissivity are validated together by radiance comparison between the observation and retrieval-based calculation in the window region where atmospheric contribution is minimized. Both simulation and validation results have lead to the conclusion that variable surface emissivity in the inversion process is needed to obtain accurate retrievals from satellite IR spectral radiance measurements. Retrieval examples are presented to reveal that surface emissivity plays a significant role in retrieving accurate surface skin temperature and TBL thermodynamic parameters.

  3. Supercollision cooling effects on the hot photoluminescence emission of graphene.

    PubMed

    Alencar, Thonimar V; Malard, Leandro M; Paula, Ana M de

    2016-09-30

    We report on hot photoluminescence measurements that show the effects of acoustic phonon supercollision processes in the intensity of graphene light emission. We use a simple optical method to induce defects on single layer graphene in a controlled manner to study in detail the light emission dependence on the sample defect density. It is now well accepted that the graphene photoluminescence is due to black-body thermal emission from the quasi-equilibrium electrons at a temperature well above the lattice temperature. Our results show that as the sample defect density is increased the electrons relax energy more efficiently via acoustic phonon supercollision processes leading to lower electron temperatures and thus lower emission intensities. The calculated intensity decrease due to supercollision energy relaxation agrees well with the experimental data.

  4. Salinity effects on the microwave emission of soils

    NASA Technical Reports Server (NTRS)

    Jackson, Thomas J.; Oneill, Peggy E.

    1987-01-01

    Controlled plot experiments were conducted to collect L and C band passive microwave data concurrent with ground observations of salinity and soil moisture. Two dielectric mixing models were used with an emission model to predict the emissivity from a bare smooth uniform profile. The models produce nearly identical results when near zero salinity is involved and reproduce the observed data at L band extremely well. Discrepancies at C band are attributed to sampling depth problems. Comparisons of predicted emissivities at various salinities with observed values indicate that the dynamic range of the emissivities can be explained using either of the dielectric mixing models. Evaluation of the entire data set, which included four salinity levels, indicates that for general application the effects of soil salinity can be ignored in interpreting microwave data for estimating soil moisture under most agricultural conditions.

  5. Effects of salinity on the microwave emission of soils

    NASA Technical Reports Server (NTRS)

    Jackson, T. J.; Oneill, P. E.

    1986-01-01

    Controlled plot experiments were conducted to collect L and C band passive microwave data concurrent with ground observations of salinity and soil moisture. Two dielectric mixing models were used with an emission model to predict the emissivity from a bare smooth uniform profile. The models produce nearly identical results when near zero salinity is involved and reproduce the observed data at L band extremely well. Discrepancies at C band are attributed to sampling depth problems. Comparisons of predicted emissivities at various salinities with observed values indicate that the dynamic range of the emissivities can be explained using either of the dielectric mixing models. Evaluation of the entire data set, which included four salinity levels, indicates that for general application the effects of soil salinity can be ignored in interpreting microwave data for estimating soil moisture under most agricultural conditions.

  6. Study shows effect of surface preparations on improving thermionic emission

    NASA Technical Reports Server (NTRS)

    Van someren, L.

    1966-01-01

    Specimen thermionic emitters were electropolished and electroetched to study the effect of surface preparations on improving thermionic emission. The best technique found was to electropolish the annealed rhenium surface and then electroetch it. The effect of electroetching was to remove other crystal planes faster than basal planes.

  7. Spontaneous emission effects in optically pumped x-ray FEL

    SciTech Connect

    Smetanin, I.V.; Grigor`ev, S.V.

    1995-12-31

    An effect of spontaneous emission in both quantum and classical regimes of the optically pumped X-ray free electron laser (FEL) in investigated. The quantum properties of an FEL are determined by the ratio of the separation {h_bar} between the absorption and emission lines (i.e. the quanta emitted) and their effective width {Delta}{epsilon} {eta}={h_bar}/{Delta}{epsilon}. In the conventional classical regime {eta} {much_lt} 1 an electron emits and absorbes a great number of shortwavelength photons over the interaction region, the gain in FEL being the result of these competitive processes. In the quantum limit {eta} {much_gt} 1 the emission and absorption lines are completely separated and thus the FEL becomes a two-level quantum oscillator with a completely inverted active medium. Spontaneous emission causes the electron to leave the range of energies where resonant interaction with the laser field occurs, thus effectively reducing the number of particles that take part in generating the induced X-ray signal. This effect is found to be crucial for lasing in optically pumped X-ray FEL. The characteristic relaxation times are calculated for both classical and quantum FEL regimes. It is shown that spontaneous emission results in FEL electron beam threshold current, which is of rather high value. An optimal range of pumping laser intensities is determined.

  8. Effects of population and affluence on CO2 emissions.

    PubMed

    Dietz, T; Rosa, E A

    1997-01-07

    We developed a stochastic version of the Impact = Population x Affluence x Technology (IPAT) model to estimate the effects of population, affluence, and technology on national CO2 emissions. Our results suggest that, for population, there are diseconomies of scale for the largest nations that are not consistent with the assumption of direct proportionality (log-linear effects) common to most previous research. In contrast, the effects of affluence on CO2 emissions appear to reach a maximum at about $10,000 in per- capita gross domestic product and to decline at higher levels of affluence. These results confirm the general value of the IPAT model as a starting point for understanding the anthropogenic driving forces of global change and suggest that population and economic growth anticipated over the next decade will exacerbate greenhouse gas emissions.

  9. Curved surface effect and emission on silicon nanostructures

    NASA Astrophysics Data System (ADS)

    Huang, Wei-Qi; Yin, Jun; Zhou, Nian-Jie; Huang, Zhong-Mei; Miao, Xin-Jian; Cheng, Han-Qiong; Su, Qin; Liu, Shi-Rong; Qin, Chao-Jian

    2013-10-01

    The curved surface (CS) effect on nanosilicon plays a main role in the activation for emission and photonic manipulation. The CS effect breaks the symmetrical shape of nanosilicon on which some bonds can produce localized electron states in the band gap. The investigation in calculation and experiment demonstrates that the different curvatures can form the characteristic electron states for some special bonding on the nanosilicon surface, which are related to a series of peaks in photoluminecience (PL), such as LN, LNO, LO1, and LO2 lines in PL spectra due to Si—N, Si—NO, Si=O, and Si—O—Si bonds on curved surface, respectively. Si—Yb bond on curved surface of Si nanostructures can provide the localized states in the band gap deeply and manipulate the emission wavelength into the window of optical communication by the CS effect, which is marked as the LYb line of electroluminescence (EL) emission.

  10. Effect of Environmental Factors on Sulfur Gas Emissions from Drywall

    SciTech Connect

    Maddalena, Randy

    2011-08-20

    per hour [{micro}g/m{sup 2}/h]. The dominant sulfur containing compounds in the RSG emission stream were hydrogen sulfide with emission factors between 17-201 {micro}g/m{sup 2}/h, and sulfur dioxide with emission factors between 8-64 {micro}g/m{sup 2}/h. The four highest emitting samples also had a unique signature of VSC emissions including > 40 higher molecular weight sulfur-containing compounds although the emission rate for the VSCs was several orders of magnitude lower than that of the RSGs. All of the high emitting drywall samples were manufactured in China in 2005-2006. Results from Phase 1 provided baseline emission factors for drywall samples manufactured in China and in North America but the results exclude variations in environmental conditions that may exist in homes or other built structures, including various combinations of temperature, RH, ventilation rate and the influence of coatings such as texture and paints. The objective of Phase 2 was to quantify the effect of temperature and RH on the RSG emission factors for uncoated drywall, and to measure the effect of plaster and paint coatings on RSG emission factors from drywall. Additional experiments were also performed to assess the influence of ventilation rate on measured emission factors for drywall.

  11. The Effects of Resource Intermittency on Electricity System Emissions

    NASA Astrophysics Data System (ADS)

    Sechrist, B.; Jacobson, M. Z.

    2015-12-01

    Since society subsidizes the production of renewable electricity in order to decrease emissions from the electric power system, it is important to quantify the environmental benefits of renewables. We use the intermittency characteristics of renewable resources to assess the impact of renewable generation on the emissions of carbon dioxide and other air pollutants. Previous studies have investigated the impact of wind or solar generation on emissions; rather than focusing on a particular technology, we separate the intermittent resource into its components - specifically variability, predictability, and timing - and isolate the effect of each component. For the Texas electricity grid, we use the observed outputs of generating units to econometrically estimate the effect of each intermittency characteristic on CO2, SO2, and NOx emissions. We then use the econometric results to evaluate and compare the expected emissions implications of adding different resources to the system. While the econometric estimates are derived from the wind currently online in Texas, the decomposition of the intermittency makes the results technology agnostic and allows for a comparison between prospective resources of different types. Preliminary results will be presented.

  12. Effects of time and height on behavior of emissions.

    PubMed Central

    Van der Hoven, I

    1975-01-01

    The effect of the two parameters is reviewed. Variability with time is discussed in relation to stability and other atmospheric conditions. The magnitude of ground level concentrations from elevated release is discussed as an interaction between rate of emission release, physical height of stack, and thermal conditions. The point is made that plant effluent rates have increased in proportion to stack height. PMID:1157787

  13. SUBSTRATE EFFECTS ON VOC EMISSIONS FROM A LATEX PAINT

    EPA Science Inventory

    The effects of two substrates -- a stainless steel plate and a gypsum board -- on the volatile organic compound (VOC) emissions from a latex paint were evaluated by environmental chamber tests. It was found that the amount of VOCs emitted from the painted stainless steel was 2 to...

  14. Effect of timed secondary-air injection on automotive emissions

    NASA Technical Reports Server (NTRS)

    Coffin, K. P.

    1973-01-01

    A single cylinder of an automotive V-8 engine was fitted with an electronically timed system for the pulsed injection of secondary air. A straight-tube exhaust minimized any mixing other than that produced by secondary-air pulsing. The device was operated over a range of engine loads and speeds. Effects attributable to secondary-air pulsing were found, but emission levels were generally no better than using the engine's own injection system. Under nontypical fast-idle, no-load conditions, emission levels were reduced by roughly a factor of 2.

  15. Secondary Electron Emission from Dust and Its Effect on Charging

    NASA Astrophysics Data System (ADS)

    Saikia, B. K.; Kakati, B.; Kausik, S. S.; Bandyopadhyay, M.

    2011-11-01

    Hydrogen plasma is produced in a plasma chamber by striking discharge between incandescent tungsten filaments and the permanent magnetic cage [1], which is grounded. The magnetic cage has a full line cusped magnetic field geometry used to confine the plasma elements. A cylindrical Langmuir probe is used to study the plasma parameters in various discharge conditions. The charge accumulated on the dust particles is calculated using the capacitance model and the dust current is measured by the combination of a Faraday cup and an electrometer at different discharge conditions. It is found Secondary electron emission from dust having low emission yield effects the charging of dust particles in presence of high energetic electrons.

  16. Secondary Electron Emission from Dust and Its Effect on Charging

    SciTech Connect

    Saikia, B. K.; Kakati, B.; Kausik, S. S.; Bandyopadhyay, M.

    2011-11-29

    Hydrogen plasma is produced in a plasma chamber by striking discharge between incandescent tungsten filaments and the permanent magnetic cage [1], which is grounded. The magnetic cage has a full line cusped magnetic field geometry used to confine the plasma elements. A cylindrical Langmuir probe is used to study the plasma parameters in various discharge conditions. The charge accumulated on the dust particles is calculated using the capacitance model and the dust current is measured by the combination of a Faraday cup and an electrometer at different discharge conditions. It is found Secondary electron emission from dust having low emission yield effects the charging of dust particles in presence of high energetic electrons.

  17. Effect of gasoline composition on stoichiometry and exhaust emissions

    SciTech Connect

    McDonald, C.R.; Lee, G.R.; Otter, G.J. den; Shore, P.R.; Humphries, D.T.

    1994-10-01

    Six full range gasolines were tested in two engines (one with a catalyst) operated at 4 steady states. Engine-out regulated emissions responded to equivalence ratio, {Phi}, in the accepted manner. For both CO and NO{sub x}, there was a characteristic, single emissions response to changes in {Phi}. Changing fuel composition will primarily alter the production of these emissions by modifying the stoichiometric air/fuel ratio, projecting engine operation onto another part of the {Phi} response curve. These {Phi} effects, which are independent of engine design, also determine how operating conditions affect engine-out CO and NO{sub x}. Speciated hydrocarbon measurements at engine-out and tail-pipe confirm results seen in previous test-cycle based programmes. 24 refs., 11 figs., 3 tabs.

  18. Effect of filament supports on emissive probe measurements

    SciTech Connect

    Wang, X.; Howes, C. T.; Horanyi, M.; Robertson, S.

    2013-01-15

    We have constructed an emissive probe with a thin tungsten filament spot-welded across two nickel wires insulated with ceramic paint. We show that the ceramic supports covering the nickel wires have a large effect on the potential measurements in low-density plasmas. It is found that the potential measured by the emissive probe is more negative than the potential derived from a Langmuir probe current-voltage (I-V) characteristic curve when the plasma density is so low that the emitting filament remains immersed in the sheaths of the ceramic supports. The length of the filament L needs to be larger than about 2 Debye lengths (L > 2{lambda}{sub De}) in order to avoid the influence of the ceramic supports and to achieve reliable plasma potential measurements using emissive probes.

  19. Ozone trends in Atlanta, Georgia - Have emission controls been effective?

    NASA Technical Reports Server (NTRS)

    Lindsay, Ronald W.; Richardson, Jennifer L.; Chameldes, William L.

    1989-01-01

    Nine years of summertime ozone data from the Atlanta metropolitan area are analyzed and compared to local emissions of volatile organic carbon and nitrogen oxides. Trends from 1979 to 1987 were studied for the number of days per year ozone exceeded the NAAQS standard, the second-highest ozone level observed per year, and the first quartile summertime average ozone observed, as well as the mean difference between the ozone level observed downwind and upwind of the city. Because this last parameter is sensitive to chemical factors but relatively insensitive to the number of days each year with meteorological conditions conducive to ozone formation, its trend may be best suited for determining how effective emission controls have been in reducing O3 in the Atlanta area. In spite of the fact that sizeable reductions have been claimed for volatile organic carbon emissions over the past several years, the data give no indication that ozone levels have decreased and in fact, imply that summertime ozone production may have increased. The results imply that either emissions have not decreased as much as has been claimed or that ozone is not sensitive to anthropogenic volatile organic carbon emissions.

  20. Effect of natural compounds on reducing formaldehyde emission from plywood

    NASA Astrophysics Data System (ADS)

    Uchiyama, Shigehisa; Matsushima, Erica; Kitao, Nahoko; Tokunaga, Hiroshi; Ando, Masanori; Otsubo, Yasufumi

    The effects of natural compounds on reducing formaldehyde emission from plywood were investigated. Urea, catechin and vanillin were examined as the natural formaldehyde reducers. The microemission cell, with an internal volume of 35 ml, the maximum exposed test surface area of 177 cm 2 and an air purge flow rate of 50 ml min -1, was used to measure specific emission rate (SER). In the case of no reducer treatment, formaldehyde emission from plywood was fast and SERs were 4.4 mg m -2 h -1 at 30 °C and 15 mg m -2 h -1 at 60 °C. When this plywood was treated with the natural compounds, the SERs of formaldehyde were decreased at all temperatures. In the case of urea treatment, the SERs of formaldehyde decreased to 0.30 mg m -2 h -1 at 30 °C and 0.65 mg m -2 h -1 at 60 °C. When the urea treatment was applied to the inside of kitchen cabinet (made from plywood; 270 cm wide, 60 cm deep, 250 cm high), the concentration of formaldehyde was reduced substantially from 1600 to 130 μg m -3. The reducing effect of formaldehyde continued during the observation period (6 months), with a mean concentration of 100 μg m -3. Reducers in the plywood would react with released formaldehyde. Application of natural compounds such as urea, catechin and vanillin could provide a simple and effective approach for suppressing formaldehyde emission from plywood.

  1. Energy and air emission effects of water supply.

    PubMed

    Stokes, Jennifer R; Horvath, Arpad

    2009-04-15

    Life-cycle air emission effects of supplying water are explored using a hybrid life-cycle assessment For the typically sized U.S. utility analyzed, recycled water is preferable to desalination and comparable to importation. Seawater desalination has an energy and air emission footprint that is 1.5-2.4 times larger than that of imported water. However, some desalination modes fare better; brackish groundwater is 53-66% as environmentally intensive as seawater desalination. The annual water needs (326 m3) of a typical Californian that is met with imported water requires 5.8 GJ of energy and creates 360 kg of CO2 equivalent emissions. With seawater desalination, energy use would increase to 14 GJ and 800 kg of CO2 equivalent emissions. Meeting the water demand of California with desalination would consume 52% of the state's electricity. Supply options were reassessed using alternative electricity mixes, including the average mix of the United States and several renewable sources. Desalination using solar thermal energy has lower greenhouse gas emissions than that of imported and recycled water (using California's electricity mix), but using the U.S. mix increases the environmental footprint by 1.5 times. A comparison with a more energy-intensive international scenario shows that CO2 equivalent emissions for desalination in Dubai are 1.6 times larger than in California. The methods, decision support tool (WEST), and results of this study should persuade decision makers to make informed water policy choices by including energy consumption and material use effects in the decision-making process.

  2. Surface effects on the microwave backscatter and emission of snow

    NASA Technical Reports Server (NTRS)

    Fung, A. K.; Stiles, W. H.; Ulaby, F. T.

    1980-01-01

    Measurements were performed with active and passive microwave sensors for both dry and wet snow conditions. A layer of Rayleigh scatterers with irregular surface boundaries is found to be a reasonable model for interpreting passive and active measurements in X- and Ku-bands. It was found that roughness had a significant effect on both backscatter and emission from wet snow; however, only a small effect was noted for dry snow.

  3. The effect of contralateral acoustic stimulation on spontaneous otoacoustic emissions.

    PubMed

    Zhao, Wei; Dhar, Sumitrajit

    2010-03-01

    Evoked otoacoustic emissions are often used to study the medial olivocochlear (MOC) efferents in humans. There has been concern that the emission-evoking stimulus may itself elicit efferent activity and alter the evoked otoacoustic emission. Spontaneous otoacoustic emissions (SOAEs) are hence advantageous as no external stimulation is necessary to record the response in the test ear. Contralateral acoustic stimulation (CAS) has been shown to suppress SOAE level and elevate SOAE frequency, but the time course of these effects is largely unknown. By utilizing the Choi-Williams distribution, here we report a gradual adaptation during the presence of CAS and an overshoot following CAS offset in both SOAE magnitude and frequency from six normal-hearing female human subjects. Furthermore, we have quantified the time constants of both magnitude and frequency shifts at the onset, presence, and offset of four levels of CAS. Most studies using contralateral elicitors do not stringently control the middle-ear muscle (MEM) reflex, leaving the results difficult to interpret. In addition to clinically available measures of the MEM reflex, we have incorporated a sensitive laboratory technique to monitor the MEM reflex in our subjects, allowing us to interpret the results with greater confidence.

  4. Cost-effective reduction of NOx emissions from electricity generation

    SciTech Connect

    Burtraw, D.; Palmer, K.; Bharvirkar, R.; Paul, A.

    2001-07-15

    This paper analyzes the benefits and costs of policies to reduce NOx emissions from electricity generation in the United States. Because emissions of NOx contribute to the high concentration of atmospheric ozone in the eastern states associated with health hazards, the US Environmental Protection Agency (EPA) has called on eastern states to formulate state implementation plans (SIPs) for reducing NOx emissions. The analysis considers three NOx reduction scenarios: a summer seasonal cap in the eastern states covered by EPA's NOx SIP call, an annual cap in the same SIP Call region, and a national annual cap. All scenarios allow for emissions trading. Although EPA's current policy is to implement a seasonal cap in the SIP Call region, this analysis indicates that an annual cap in the SIP Call region would yield about 400 million dollars more in net benefits (benefits less costs) than would a seasonal policy, based on particulate-related health effects only. An annual cap in the SIP Call region is also the policy that is most likely to achieve benefits in excess of costs. Consideration of omissions from this accounting, including the potential benefits from reductions in ozone concentrations, strengthens the finding that an annual program offers greater net benefits than does a seasonal program. 22 refs., 1 fig., 10 tabs.

  5. Atomic Auger Doppler effects upon emission of fast photoelectrons.

    PubMed

    Simon, Marc; Püttner, Ralph; Marchenko, Tatiana; Guillemin, Renaud; Kushawaha, Rajesh K; Journel, Loïc; Goldsztejn, Gildas; Piancastelli, Maria Novella; Ablett, James M; Rueff, Jean-Pascal; Céolin, Denis

    2014-06-06

    Studies of photoemission processes induced by hard X-rays including production of energetic electrons have become feasible due to recent substantial improvement of instrumentation. Novel dynamical phenomena have become possible to investigate in this new regime. Here we show a significant change in Auger emission following 1s photoionization of neon, which we attribute to the recoil of the Ne ion induced by the emission of a fast photoelectron. Because of the preferential motion of the ionized Ne atoms along two opposite directions, an Auger Doppler shift is revealed, which manifests itself as a gradual broadening and doubling of the Auger spectral features. This Auger Doppler effect should be a general phenomenon in high-energy photoemission of both isolated atoms and molecules, which will have to be taken into account in studies of other recoil effects such as vibrational or rotational recoil in molecules, and may also have consequences in measurements in solids.

  6. Acoustic emission and shape memory effect in the martensitic transformation.

    PubMed

    Sreekala, S; Ananthakrishna, G

    2003-04-04

    Acoustic emission signals are known to exhibit a high degree of reproducibility in time and show correlations with the growth and shrinkage of martensite domains when athermal martensites are subjected to repeated thermal cycling in a restricted temperature range. We show that a recently introduced two dimensional model for the martensitic transformation mimics these features. We also show that these features are related to the shape memory effect where near full reversal of morphological features are seen under these thermal cycling conditions.

  7. Health effects of SRS non-radiological air emissions

    SciTech Connect

    Stewart, J.

    1997-06-16

    This report examines the potential health effects of non radiological emissions to the air resulting from operations at the Savannah River Site (SRS). The scope of this study was limited to the 55 air contaminants for which the US Environmental Protection Agency (EPA) has quantified risk by determining unit risk factors (excess cancer risks) and/or reference concentrations (deleterious non cancer risks). Potential health impacts have been assessed in relation to the maximally exposed individual. This is a hypothetical person who resides for a lifetime at the SRS boundary. The most recent (1994) quality assured SRS emissions data available were used. Estimated maximum site boundary concentrations of the air contaminants were calculated using air dispersion modeling and 24-hour and annual averaging times. For the emissions studied, the excess cancer risk was found to be less than the generally accepted risk level of 1 in 100,000 and, in most cases, was less than 1 in 1,000,000. Deleterious non cancer effects were also found to be very unlikely.

  8. Microlensing Effects on Emission Lines from Homologously Expanding Winds

    NASA Astrophysics Data System (ADS)

    Ignace, R.; Bryce, H. M.; Hendry, M. A.

    2004-12-01

    We have been investigating the influence of microlensing on a variety of spectroscopic signatures relevant to circumstellar flows. Here we report on recent results for line profiles that form in spherically symmetric winds during a microlensing event. As a convenient test case, we have adopted a homologous velocity law (v ∝ r, from r=Rphot to rmax). Results are discussed for resonance scattering P Cygni lines and recombination emission lines. Somewhat surprisingly, the rectified line profiles show rather mild variations in response to microlensing. The reason is that both the line emission from the extended wind and the stellar photosphere are lensed, so that the strong magnification effects of lensing seen in either component are partially supressed when showing the continuum normalized spectrum (which is the common form of display for such data). Still, significant and observable variations in the line equivalent width do result. This research has been supported in part by NSF grant AST-0354261.

  9. Volcanic gas emissions and their effect on ambient air character

    SciTech Connect

    Sutton, A.J.; Elias, T.

    1994-01-01

    This bibliography was assembled to service an agreement between Department of Energy and the USGS to provide a body of references and useful annotations for understanding background gas emissions from Kilauea volcano. The current East Rift Zone (ERZ) eruption of Kilauea releases as much as 500,000 metric tonnes of SO{sub 2} annually, along with lesser amounts of other chemically and radiatively active species including H{sub 2}S, HCl, and HF. Primary degassing locations on Kilauea are located in the summit caldera and along the middle ERZ. The effects of these emissions on ambient air character are a complex function of chemical reactivity, source geometry and effusivity, and local meteorology. Because of this complexity, we organized the bibliography into three main sections: (1) characterizing gases as they leave the edifice; (2) characterizing gases and chemical reaction products away from degassing sources; and (3) Hawaii Island meteorology.

  10. Effects of Enhanced Eathode Electron Emission on Hall Thruster Operation

    SciTech Connect

    Y. Raitses, A. Smirnov and N. J. Fisch

    2009-04-24

    Interesting discharge phenomena are observed that have to do with the interaction between the magnetized Hall thruster plasma and the neutralizing cathode. The steadystate parameters of a highly ionized thruster discharge are strongly influenced by the electron supply from the cathode. The enhancement of the cathode electron emission above its self-sustained level affects the discharge current and leads to a dramatic reduction of the plasma divergence and a suppression of large amplitude, low frequency discharge current oscillations usually related to an ionization instability. These effects correlate strongly with the reduction of the voltage drop in the region with the fringing magnetic field between the thruster channel and the cathode. The measured changes of the plasma properties suggest that the electron emission affects the electron cross-field transport in the thruster discharge. These trends are generalized for Hall thrusters of various configurations.

  11. [Effects of land management measures on nutrients emission].

    PubMed

    Xu, Qi-Gong; Xi, Bei-Dou; Yu, Hui-Bin; Tang, Zhen-Wu; Gao, Ru-Tai; Xia, Xun-Feng

    2009-11-01

    The SWAT model, coupled with a GIS, was applied to simulate the effects of fertilizer application, contour planting and returning land for farming to forestry on nutrients discharges. The results showed that when nitrogen fertilizer of agricultural land increased from 630 to 955 kg/hm2, and phosphorus fertilizer increased from 200 to 300 kg/hm2, nitrogen and phosphorus nutrient emissions have shown a growing trend. Nitrate nitrogen loads reached to 3 776.59 kg which increased 19.7% and the rate of changes was the largest. The change rate of inorganic phosphorus was the smallest which increased only 2.7%. The impact of emission loads on nitrogen and phosphorus was the smallest if contour planting was adopted. When slope farmland which slope is greater than 25% all returned land for farming to forestry, the emission loads of various forms of nitrogen and phosphorus decreased, organic phosphorus decreased 16.3% among them. Organic nitrogen, ammonia nitrogen and inorganic phosphorus compared with before returning land for farming to forestry, decreased 22.7%, 25.4% and 27.9% respectively. In small basin of Zhangjiachong, returning farmlands to forests and reducing the amount of chemical fertilizer on the slope farmlands which slopes are larger than 25% have played a prominent role.

  12. Effect of secondary electron emission on the plasma sheath

    SciTech Connect

    Langendorf, S. Walker, M.

    2015-03-15

    In this experiment, plasma sheath potential profiles are measured over boron nitride walls in argon plasma and the effect of secondary electron emission is observed. Results are compared to a kinetic model. Plasmas are generated with a number density of 3 × 10{sup 12} m{sup −3} at a pressure of 10{sup −4} Torr-Ar, with a 1%–16% fraction of energetic primary electrons. The sheath potential profile at the surface of each sample is measured with emissive probes. The electron number densities and temperatures are measured in the bulk plasma with a planar Langmuir probe. The plasma is non-Maxwellian, with isotropic and directed energetic electron populations from 50 to 200 eV and hot and cold Maxwellian populations from 3.6 to 6.4 eV and 0.3 to 1.3 eV, respectively. Plasma Debye lengths range from 4 to 7 mm and the ion-neutral mean free path is 0.8 m. Sheath thicknesses range from 20 to 50 mm, with the smaller thickness occurring near the critical secondary electron emission yield of the wall material. Measured floating potentials are within 16% of model predictions. Measured sheath potential profiles agree with model predictions within 5 V (∼1 T{sub e}), and in four out of six cases deviate less than the measurement uncertainty of 1 V.

  13. Diesel Emission Control -- Sulfur Effects (DECSE) Program; Phase I Interim Date Report No. 3: Diesel Fuel Sulfur Effects on Particulate Matter Emissions

    SciTech Connect

    DOE; ORNL; NREL; EMA; MECA

    1999-11-15

    The Diesel Emission Control-Sulfur Effects (DECSE) is a joint government/industry program to determine the impact of diesel fuel sulfur levels on emission control systems whose use could lower emissions of nitrogen oxides (NO{sub x}) and particulate matter (PM) from on-highway trucks in the 2002--2004 model years. Phase 1 of the program was developed with the following objectives in mind: (1) evaluate the effects of varying the level of sulfur content in the fuel on the emission reduction performance of four emission control technologies; and (2) measure and compare the effects of up to 250 hours of aging on selected devices for multiple levels of fuel sulfur content. This interim report covers the effects of diesel fuel sulfur level on particulate matter emissions for four technologies.

  14. Target current density effects in al-cluster ion emission

    NASA Astrophysics Data System (ADS)

    Ray, N.; Rajasekar, P.; Chakraborty, P.; Dey, S. D.

    1994-04-01

    Target current density effects in secondary emission of positively-charged sputtered clusters from an ion-bombarded polycrystalline aluminium surface have been investigated for various primary Cd+ ion energies. For each cluster type, at medium target current densities (Jp : 0?350 ?A/cm2), apart from the presence of the expected linear term in the I+ s α Jp curves, there is a square law term, depicting that some fraction of the pre-emitted neutral clusters gets ionized in vacuum above the target surface. Thus, a sum of these two terms constitutes the total cluster ion current which shows a non-linear dependence on the target current density. At higher target current densities (350 ?A cm?2?1.05 mA cm?2), in addition to the parabolic effect, a higher order non-linearity comes into play and the net cluster ion current I + s , measured as a function of target current density within the Ip range concerned, can be expressed in terms of our previously proposed semi-empirical formula I+ s = C.Ip + D.I2 p + F.In p , which was earlier found to be applicable in case of single and double charged secondary monomers. A higher power (n > 2) dependence has been observed here for the first time in case of cluster ion emission, suggesting chemical enhancement of secondary clusters. Our present observations seem to support ?direct emission model? even for small metal clusters?a proposition which is in apparent contradiction to the current notion in this field, i.e. vacuum recombination of individual atoms in small cluster formation.

  15. Effect of soil texture on the microwave emission from soils

    NASA Technical Reports Server (NTRS)

    Schmugge, T. J.

    1980-01-01

    The intensity brightness temperature of the microwave emission from the soil is determined primarily by its dielectric properties. The large difference between the dielectric constant of water and that of dry soil produces a strong dependence of the soil's dielectric constant on its moisture content. This dependence is effected by the texture of the soil because the water molecules close to the particle surface are tightly bound and do not contribute significantly to the dielectric properties. Since this surface area is a function of the particle size distribution (soil texture), being larger for clay soils with small particles, and smaller for sandy soils with larger particles; the dielectric properties will depend on soil texture. Laboratory measurements of the dielectric constant for soils are summarized. The dependence of the microwave emission on texture is demonstrated by measurements of brightness temperature from an aircraft platform for a wide range of soil textures. It is concluded that the effect of soil texture differences on the observed values can be normalized by expressing the soil moisture values as a percent field capacity for the soil.

  16. Effect of phosphogypsum on respiration and methane emissions in sediment.

    PubMed

    DeLaune, R D; Porthouse, J D; Patrick, W H

    2006-05-01

    The impact of adding phosphogypsum (PG) to freshwater wetland areas, and potential effect on methane production and respiration in sediment was studied in the laboratory. Two organic matter levels (native and enriched with 0.5% by weight ground dry plant material) were studied using five sediment treatments each: (1) no PG added, (2) 4% PG by dry weight (homogenized), (3) 20% PG by dry weight (homogenized), (4) 2000 kg ha(-1) (surface applied), and (5) 5000 kg ha (surface applied), and the experiment was run in triplicate. There was a net flux of methane into sediment for all treatments that were maintained at the native organic matter level, indicating net methane oxidation. In the organic-enriched cores, both of the homogenized treatments exhibited no methane emissions, while the surface applied treatments retained the potential for high emissions. Soil respiration was depressed in all treatments when compared to controls, especially in the organic-enriched cores. The results conclude that it may be possible to add PG to non-vegetated areas with few observable effects on sediment respiration, but organic matter content and method of application are critical concerns.

  17. Effect of gasoline/methanol blends on motorcycle emissions: Exhaust and evaporative emissions

    NASA Astrophysics Data System (ADS)

    Li, Lan; Ge, Yunshan; Wang, Mingda; Li, Jiaqiang; Peng, Zihang; Song, Yanan; Zhang, Liwei

    2015-02-01

    The emission characteristics of motorcycles using gasoline and M15 (consisting of 85% gasoline and 15% methanol by volume) were investigated in this article. Exhaust and evaporative emissions, including regulated and unregulated emissions, of three motorcycles were investigated on the chassis dynamometer over the Urban Driving Cycle (UDC) and in the Sealed Housing for Evaporative Determination (SHED), respectively. The regulated emissions were detected by an exhaust gas analyzer directly. The unregulated emissions, including carbonyls, volatile organic compounds (VOCs) and methanol, were sampled through battery-operated air pumps using tubes coated with 2,4-dintrophenylhydrazine (DNPH), Tenax TA and silica gel, respectively. The experimental results showed that, for exhaust emission, compared with those from gasoline fueled motorcycles, the concentration of total hydrocarbons (THC) and CO from motorcycles fueled with M15 decreased by 11%-34.5% and 63%-84% respectively, while the concentration of NOx increased by 76.9%-107.7%. Compared with those from gasoline fueled motorcycles, BTEX from motorcycles fueled with M15 decreased by 16%-60% while formaldehyde increased by 16.4%-52.5%. For evaporative emission, diurnal losses were more than hot soak losses and turned out to be dominated in evaporative emissions. In addition, compared with gasoline fueling motorcycles, the evaporative emissions of THC, carbonyls and VOCs from motorcycles fueled with M15 increased by 11.7%-37%, 38%-45% and 16%-42%, respectively. It should be noted that the growth rate of methanol was as high as 297%-1429%. It is important to reduce the evaporative emissions of methanol fueling motorcycles.

  18. Toxicity and health effects of vehicle emissions in Shanghai

    NASA Astrophysics Data System (ADS)

    Ye, Shun-Hua; Zhou, Wei; Song, Jian; Peng, Bao-Cheng; Yuan, Dong; Lu, Yuan-Ming; Qi, Ping-Ping

    In China, the number of vehicles is increasing rapidly with the continuous development of economy, and vehicle emission pollution in major cities is more serious than ever. In this article, we summarized the results of a series of short-term assays, animal experiments and epidemiology investigations on the genotoxicity, immunotoxicity, respiratory toxicity and health effects of vehicle emissions in Shanghai, including gasoline exhausts (gas condensate and particles), diesel exhaust particles (DEP) and scooter exhaust particles (SEP). The results showed that: (1) Both gases and particulate phases of the exhausts of different kinds of vehicles showed strong mutagenicity in Ames test (TA98 and TA100 strains), rat hepatocyte unscheduled DNA synthesis (UDS) assay, and mouse micronucleus assay, and vehicle emissions could induce the transformation of Syrian hamster embryo (SHE) cells. DEP and SEP could induce the transformation of human diploid cell strain (KMB-13) cells, immunohistochemistry assay showed that c-myc and p21 proteins were highly expressed in the transformed cells. DEP and SEP could also inhibit the gap junctional intercellular communication (GJIC) of BALB/C3T3 cells (2) Vehicle emissions could decrease the number of macrophages in the lung (bronchial alveolar lavage fluid) (BALF) of male SD rats. Vehicle emissions could also increase the proportion of polymorphonuclear leukocytes (PMN), the content of cetyneuraminic acid (NA), the activity of lactate dehydrogenase (LDH), alkali phosphate (AKP), acid phosphate (ACP) in the lung BALF of the animals. (3) In epidemiology investigation, the proportion of those who have respiratory symptoms and chronic obstructive pulmonary diseases (COPD) in the workers who were exposed to DEP ( n=806) were much higher than those of the controls ( n=413). The OR (odd ratio) values of angina, nasal obstruction, phlegm, short of breath and COPD were 2.27, 3.08, 3.00, 3.19 and 2.32, respectively, and the proportion of those who

  19. EFFECT OF VEHICLE CHARACTERISTICS ON UNPAVED ROAD DUST EMISSIONS

    EPA Science Inventory

    This paper presents PM10 fugitive dust emission factors for a range of vehicles types and examines the influence of vehicle and wake characteristics on the strength of emissions from an unpaved road.

  20. [Effect of economic structure adjustment on pollution emission: a case study of COD].

    PubMed

    Li, Ming-Sheng; Zhou, Lei; Chen, Yuan-Hang; Li, Qian; Zhang, Jian-Hui

    2014-08-01

    Economic structure adjustment is an important means to reduce the emissions of pollutants. For quantitative analysis of the effect of economic structure adjustment on the reduction of pollution emission, the country was divided into four sub-regions, eastern, northeastern, central and western, and the industry was divided into 39 sectors. Taking chemical oxygen demand (COD) as an example, the influences of regional structure and industry structure adjustment on total emission reduction and emission intensity were analyzed through building a model. The results showed that, in 2000-2010: (1) COD emissions in China were reduced from 1 445 x 10(4) t to 1 238 x 10(4) t, with a total emission of 14 950 x 10(4) t in 11 years, among which the emissions from eastern area occupied the largest proportion, accounting for 35.6%. (2) In the industrial COD emissions, emission from paper and paper products was the largest, accounting for 35.8% of the industrial COD emissions. (3) The economic structure changes in the four areas reduced the COD emissions by 420 x 10(4) t, resulting in a decrease of 1.29% in COD emission intensity. (4) Industrial internal structure changes reduced the COD emissions by 533 x 10(4) t, leading to a decrease of 3.1% in COD emission intensity. The research results have certain reference value in guiding the Chinese economic structure adjustment and achieving the targets of energy-saving and emission reduction.

  1. Radiative Transfer Effects in He I Emission Lines

    NASA Astrophysics Data System (ADS)

    Benjamin, Robert A.; Skillman, Evan D.; Smits, Derck P.

    2002-04-01

    We consider the effect of optical depth of the 23S level on the nebular recombination spectrum of He I for a spherically symmetric nebula with no systematic velocity gradients. These calculations, using many improvements in atomic data, can be used in place of the earlier calculations of Robbins. We give representative Case B line fluxes for UV, optical, and IR emission lines over a range of physical conditions: T=5000-20,000 K, ne=1-108 cm-3, and τ3889=0-100. A FORTRAN program for calculating emissivities for all lines arising from quantum levels with n<=10 is also available from the authors. We present a special set of fitting formulae for the physical conditions relevant to low-metallicity extragalactic H II regions: T=12,000-20,000 K, ne=1-300 cm-3, and τ3889<2.0). For this range of physical conditions, the Case B line fluxes of the bright optical lines 4471 Å, 5876 Å, and 6678 Å, are changed less than 1%, in agreement with previous studies. However, the 7065 Å corrections are much smaller than those calculated by Izotov & Thuan based on the earlier calculations by Robbins. This means that the 7065 Å line is a better density diagnostic than previously thought. Two corrections to the fitting functions calculated in our previous work are also given.

  2. Triton Emission Spectra in Some Target Nuclei Irradiated by Ultra-Fast Neutrons

    NASA Astrophysics Data System (ADS)

    Tel, E.; Kaplan, A.; Aydın, A.; Büyükuslu, H.; Demirkol, İ.; Arasoğlu, A.

    2010-08-01

    High-current proton accelerator technologies make use of spallation neutrons produced in ( p,xn) and ( n,xn) nuclear reactions on high-Z targets. The produced neutrons are moderated by heavy water. These moderated neutrons are subsequently captured on 3He to produce tritium via the ( n,p) reaction. Tritium self-sufficiency must be maintained for a commercial power plant. So, working out the systematics of ( n,t) reaction cross sections and triton emission differential data are important for the given reaction taking place on various nuclei at different energies. In this study, triton emission spectra by using ultra-fast neutrons (incident neutron energy >50 MeV), the ( n,xt) reactions for some target nuclei as 16O, 27Al, 56Fe, 59Co, 208Pb and 209Bi have been investigated. In the calculations, the pre-equilibrium and equilibrium effects have been used. The calculated results have been compared with the experimental data taken from the literature.

  3. Emissions and fuel economy effects of vehicle exhaust emission control device (revision). Technical report

    SciTech Connect

    Johnson, H.

    1998-10-01

    This report describes testing by EPA of the Vehicle Exhaust Emission Control Device (VEECD) retrofit device under Section 32918 of Title 49 U.S.C. Retrofit Devices (RD). The VEECD is described by the developer in the international patent application as an embodiment of air bleed principle. It is intended to be retrofitted to vehicles produced without any, or with earlier-technology emission control systems. The developer claims (RD Application Appendix A) that the valve significantly reduces CO and HC emissions without substantially increasing CO{sub 2} or NOx emissions. Incidental city fuel economy enhancement was also claimed. Non-FTP test data obtained for 1986/87 European vehicles from two laboratories in the UK was submitted. This data (Appendix B) was analyzed using the t-test for the difference of constant speed data (30/60/85MPH) at 95% confidence level.

  4. Effects of solid barriers on dispersion of roadway emissions

    NASA Astrophysics Data System (ADS)

    Schulte, Nico; Snyder, Michelle; Isakov, Vlad; Heist, David; Venkatram, Akula

    2014-11-01

    Several studies have found that exposure to traffic-generated air pollution is associated with several adverse health effects. Field studies, laboratory experiments, and numerical simulations indicate that roadside barriers represent a practical method of mitigating the impact of vehicle emissions because near road concentrations are significantly reduced downwind of a barrier relative to concentrations in the absence of a barrier. These studies also show that the major effects of barriers on concentrations are: 1) the concentration is well mixed over a height roughly proportional to the barrier height, and this effect persists over several barrier heights downwind, 2) the turbulence that spreads the plume vertically is increased downwind of the barrier, 3) the pollutant is lofted above the top of the barrier. This paper ties these effects together using two semi-empirical dispersion models. These models provide good descriptions of concentrations measured in a wind tunnel study and a tracer field study. Their performance is best during neutral and stable conditions. The models overestimate concentrations near the barrier during unstable conditions. We illustrate an application of these models by estimating the effect of barrier height on concentrations during neutral, stable, and unstable conditions.

  5. A parameterization of effective soil temperature for microwave emission

    NASA Technical Reports Server (NTRS)

    Choudhury, B. J.; Schmugge, T. J.; Mo, T. (Principal Investigator)

    1981-01-01

    A parameterization of effective soil temperature is discussed, which when multiplied by the emissivity gives the brightness temperature in terms of surface (T sub o) and deep (T sub infinity) soil temperatures as T = T sub infinity + C (T sub o - T sub infinity). A coherent radiative transfer model and a large data base of observed soil moisture and temperature profiles are used to calculate the best-fit value of the parameter C. For 2.8, 6.0, 11.0, 21.0 and 49.0 cm wavelengths. The C values are respectively 0.802 + or - 0.006, 0.667 + or - 0.008, 0.480 + or - 0.010, 0.246 + or - 0.009, and 0,084 + or - 0.005. The parameterized equation gives results which are generally within one or two percent of the exact values.

  6. Effect of thermal power plant emissions on Catharanthus roseus L

    SciTech Connect

    Khan, A.M.; Pandey, V.; Shukla, J.; Singh, N.; Yunus, M.; Singh, S.N.; Ahmad, K.J. )

    1990-06-01

    Most of the industrialized nations depend largely on the combustion of fossil fuels for their energy requirements. During the past few years in India quite a few thermal power plants have been commissioned to cater to the increasing energy requirements. As most of the power plants are coal-fired, a complex mixture of several pollutants is released in the atmosphere on the combustion of coal. Leaves by virtue of their unique position on plants and their functions, experience the maximum brunt of exposure and undergo certain changes in form, structure and function with the changes in surrounding environs, and such modifications are likely to serve as markers of environmental pollution. The present paper deals with the long term exposure effects of thermal power plant emissions on Catharanthus roseus L. - a common perennial shrub, with glossy leaves and white, mauve or pink colored flowers and of great medicinal value is grown as an ornamental plant all over the country.

  7. Characterization of air freshener emission: the potential health effects.

    PubMed

    Kim, Sanghwa; Hong, Seong-Ho; Bong, Choon-Keun; Cho, Myung-Haing

    2015-01-01

    Air freshener could be one of the multiple sources that release volatile organic compounds (VOCs) into the indoor environment. The use of these products may be associated with an increase in the measured level of terpene, such as xylene and other volatile air freshener components, including aldehydes, and esters. Air freshener is usually used indoors, and thus some compounds emitted from air freshener may have potentially harmful health impacts, including sensory irritation, respiratory symptoms, and dysfunction of the lungs. The constituents of air fresheners can react with ozone to produce secondary pollutants such as formaldehyde, secondary organic aerosol (SOA), oxidative product, and ultrafine particles. These pollutants then adversely affect human health, in many ways such as damage to the central nervous system, alteration of hormone levels, etc. In particular, the ultrafine particles may induce severe adverse effects on diverse organs, including the pulmonary and cardiovascular systems. Although the indoor use of air freshener is increasing, deleterious effects do not manifest for many years, making it difficult to identify air freshener-associated symptoms. In addition, risk assessment recognizes the association between air fresheners and adverse health effects, but the distinct causal relationship remains unclear. In this review, the emitted components of air freshener, including benzene, phthalate, and limonene, were described. Moreover, we focused on the health effects of these chemicals and secondary pollutants formed by the reaction with ozone. In conclusion, scientific guidelines on emission and exposure as well as risk characterization of air freshener need to be established.

  8. Orientation effects on spectral emission features of quasars

    NASA Astrophysics Data System (ADS)

    Bisogni, Susanna; Marconi, Alessandro; Risaliti, Guido

    2017-01-01

    We present an analysis of the orientation effects in Sloan Digital Sky Survey (SDSS) quasar composite spectra. In a previous work, we have shown that the equivalent width (EW) of the [O III] λ5007 Å (vacuum rest wavelength 5008.24 Å) line is a reliable indicator of the inclination of the accretion disc. Here, we have selected a sample of ˜12 000 quasars from the SDSS 7th Data Release and divided it in subsamples with different values of EW_{[{O {III}]}}. We find inclination effects both on broad and narrow quasars emission lines, among which an increasing broadening from low to high EW for the broad lines and a decreasing importance of the blue component for the narrow lines. These effects are naturally explained with a variation of source inclination from nearly face-on to edge-on, confirming the goodness of EW_{[{O {III}]}} as an orientation indicator. Moreover, we suggest that orientation effects could explain, at least partially, the origin of the anticorrelation between [O III] and Fe II intensities, i.e. the well-known eigenvector 1.

  9. Compensating for sink effects in emissions test chambers by mathematical modeling

    NASA Astrophysics Data System (ADS)

    Dunn, James E.; Tichenor, Bruce A.

    Evidence is presented that interior surfaces of a state-of-the-art emissions test chamber can act as a transient sink for organic emissions. The major contribution of this paper is to present a class of mechanistic, mathematical models which accounts for this phenomenon as well as the effect of increasing chamber concentration on the emission rate of the source. A key point is that the effect of the chamber sink can be adjusted out simply by first fitting the appropriate model, then setting to zero the rate constant which governs sink adsorption-absorption. As a consequence of this mathematical development, a source emission rate as a function of time and a steady-state emission rate factor are given precise definitions. Applications involve modeling 1,4-dichlorobenzene emission from moth crystal cake, and mixed emissions from latex caulk. In the first case, at a low air exchange rate and low humidity, the repressive effect of increasing vapor pressure tends to overshadow the sink effect. Increased humidity tends to offset the increase in emission rate which otherwise would occur with increased air exchange. Temperature is the principal determinant of the steady-state emission rate. For the latex caulk, the effect of a sink is to retard the apparent emission rate but lengthen the period of emissions.

  10. Time-Dependent SSC Cooling Effects on Blazar Emission

    NASA Astrophysics Data System (ADS)

    Zacharias, Michael; Schlickeiser, Reinhard

    2014-03-01

    Blazars are among the most violent sources in the cosmos exhibiting flaring states with remarkably different variability time scales. Especially rapid flares with flux doubling time scales of the order of minutes have been puzzling for quite some time. Many modeling attempts use the well known linear and steady-state scenario for the cooling and emission processes in the jet, albeit the obvious strongly time-dependent nature of flares. Due to the feedback of the self-produced synchrotron radiation with additional scattering by the relativistic electrons, the synchrotron-self Compton (SSC) effect is inherently time-dependent. Recently, an analytical analysis on the effects of this nonlinear behavior has been presented. Here, we summarize these results concerning the effect of the time-dependent SSC cooling on the spectral energy distribution (SED), and the synchrotron lightcurves of blazars. For that, we calculated analytically the synchrotron, SSC and external Compton (EC) component of the SED, giving remarkably different spectral features compared to the standard linear approach. The resulting fluxes strongly depend on the parameters, and SSC might have a strong effect even in sources with strong external photon fields (such as FSRQs). For the synchrotron lightcurve we considered the effects of retardation, including the geometry of the source. The retardation might smear out some effects of the time-dependent cooling, but since lightcurves and SEDs have to be fitted simultaneously with the same set of parameters, the results give nonetheless important clues about the source. Thus, we argue for a wide utilization of the time-dependent treatment in modeling (especially rapid) blazar flares, since it accounts for features in the SED and the lightcurves that are usually accounted for by introducing several breaks in the electron distribution without any physical justification.

  11. NOx Emission Reduction and its Effects on Ozone during the 2008 Olympic Games

    SciTech Connect

    Yang, Qing; Wang, Yuhang; Zhao, Chun; Liu, Zhen; Gustafson, William I.; Shao, Min

    2011-07-15

    We applied a daily-assimilated inversion method to estimate NOx (NO+NO2) emissions for June-September 2007 and 2008 on the basis of the Aura Ozone Monitoring Instrument (OMI) observations of nitrogen dioxide (NO2) and model simulations using the Regional chEmistry and trAnsport Model (REAM). Over urban Beijing, rural Beijing, and the Huabei Plain, OMI column NO2 reductions are approximately 45%, 33%, and 14%, respectively, while the corresponding anthropogenic NOx emission reductions are only 28%, 24%, and 6%, during the full emission control period (July 20 – Sep 20, 2008). The emission reduction began in early July and was in full force by July 20, corresponding to the scheduled implementation of emission controls over Beijing. The emissions did not appear to recover after the emission control period. Meteorological change from summer 2007 to 2008 is the main factor contributing to the column NO2 decreases not accounted for by the emission reduction. Model simulations suggest that the effect of emission reduction on ozone concentrations over Beijing is relatively minor using a standard VOC emission inventory in China. With an adjustment of the model emissions to reflect in situ observations of VOCs in Beijing, the model simulation suggests a larger effect of the emission reduction.

  12. Soy Biodiesel Emissions Have Reduced Inflammatory Effects Compared to Diesel Emissions in Healthy and Allergic Mice

    EPA Science Inventory

    Toxicity of exhaust from combustion of petroleum diesel (BO), soy-based biodiesel (B100), or a 20% biodiesel/80% petrodiesel mix (B20) was compared in healthy and house dust mite (HDM)-allergic mice. Fuel emissions were diluted to target fine particulate matter (PM2.5) conrentrat...

  13. Heavy Ion Radiation Effects Studies With Ion Photon Emission Microscopy

    SciTech Connect

    Branson, J. V.; Hattar, K.; Vizkelethy, G.; Powell, C. J.; Doyle, B. L.; Rossi, P.

    2011-06-01

    The development of a new radiation effects microscopy (REM) technique is crucial as emerging semiconductor technologies demonstrate smaller feature sizes and thicker back end of line (BEOL) layers. To penetrate these materials and still deposit sufficient energy into the device to induce single event effects, high energy heavy ions are required. Ion photon emission microscopy (IPEM) is a technique that utilizes coincident photons, which are emitted from the location of each ion impact to map out regions of radiation sensitivity in integrated circuits and devices, circumventing the obstacle of focusing high-energy heavy ions. Several versions of the IPEM have been developed and implemented at Sandia National Laboratories (SNL). One such instrument has been utilized on the microbeam line of the 6 MV tandem accelerator at SNL. Another IPEM was designed for ex-vacu use at the 88'' cyclotron at Lawrence Berkeley National Laboratory (LBNL). Extensive engineering is involved in the development of these IPEM systems, including resolving issues with electronics, event timing, optics, phosphor selection, and mechanics. The various versions of the IPEM and the obstacles, as well as benefits associated with each will be presented. In addition, the current stage of IPEM development as a user instrument will be discussed in the context of recent results.

  14. Effects of soil tillage on the microwave emission of soils

    NASA Technical Reports Server (NTRS)

    Jackson, T. J.; Koopman, G. J.; Oneill, P. E.; Wang, J. R.

    1985-01-01

    In order to understand the interactions of soil properties and microwave emission better, a series of field experiments were conducted in 1984. Small plots were measured with a truck-mounted passive microwave radiometer operating at 1.4 GHz. These data were collected concurrent with ground observations of soil moisture and bulk density. Treatment effects studied included different soil moisture contents and bulk densities. Evaluations of the data have shown that commonly used models of the dielectric properties of wet soils do not explain the observations obtained in these experiments. This conclusion was based on the fact that the roughness parameters determined through optimization were significantly larger than those observed in similar investigations. These discrepancies are most likely due to the soil structure. Commonly used models assume a homogeneous three phase mixture of soil solids, air and water. Under tilled conditions the soil is actually a two phase mixture of aggregates and voids. Appropriate dielectric models for this tilled condition were evaluated and found to explain the observations. These results indicate that previous conclusions concerning the effects of surface roughness in tilled fields may be incorrect, and they may explain some of the inconsistencies encountered in roughness modeling.

  15. Effects of nitrogen fertilizer types on nitrous oxide emissions

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  16. Effects of climate change on volatile organic compound emissions from soil and litter

    NASA Astrophysics Data System (ADS)

    Gray, C. M.; Fierer, N.

    2012-12-01

    Our knowledge of the variability and magnitude of volatile organic compound (VOC) emissions from soil and litter is relatively limited compared to what we know about VOC emissions from terrestrial plants. With climate change expecting to alter plant community composition, nitrogen (N) deposition rates, mean annual temperatures, and precipitation patterns, it is unknown how production and consumption of VOCs from litter and soil will respond. We spent the last four years quantifying VOC emissions from soil and litter, comparing VOC emissions to CO2 emissions, and identifying the biotic and abiotic controls on emission rates with both lab and field experiments using a proton transfer reaction mass spectrometer (PTR-MS). In all studies, methanol was the dominant VOC flux. VOC emissions were not driven by abiotic processes, as microbial sources accounted for 78% to 99% of the total VOC emissions from decomposing litter. Litter chemistry was correlated with the types of VOCs emitted and the net emissions of carbon as VOCs was found to be up to 88% of that emitted as CO2 suggesting that VOCs likely represent an important component of the carbon cycle in many terrestrial systems. Nitrogen additions drastically reduced VOC emissions from litter to near zero, though it is still not understood whether this was due to an increase in consumption or a decrease in production. Finally, field and lab experiments show that temperature and moisture are both important controls of certain VOC emissions from soils, but that the effects of these factors on VOC emissions are not necessarily equivalent to their effects on CO2 emissions. Together, these series of studies are moving us toward a predictive understanding of VOC emissions from soil and litter with the ultimate goal of incorporating these VOC emissions into global models of terrestrial VOC dynamics.

  17. Effect of vehicle characteristics on unpaved road dust emissions

    NASA Astrophysics Data System (ADS)

    Gillies, J. A.; Etyemezian, V.; Kuhns, H.; Nikolic, D.; Gillette, D. A.

    This paper presents PM 10 fugitive dust emission factors for a range of vehicles types and examines the influence of vehicle and wake characteristics on the strength of emissions from an unpaved road. Vertical profile measurements of mass concentration of the passing plumes were carried out using a series of 3 instrumented towers. PM 10 emission fluxes at each tower were calculated from knowledge of the vertical mass concentration profile, the ambient wind speed and direction, and the time the plume took to pass the towers. The emission factors showed a strong linear dependence on speed and vehicle weight. Emission factors (EF=grams of PM 10 emitted per vehicle kilometer traveled) ranged from approximately EF=0.8×(km h -1) for a light (˜1200 kg) passenger car to EF=48×(km h -1) for large military vehicles (˜18 000 kg). In comparison to emission estimates derived using US EPA AP-42 methods the measured emission factors indicate larger than estimated contributions for speeds generally>10-20 km h -1 and for vehicle weights>3000 kg. The size of a wake created by a vehicle was observed to be dependent on the size of the vehicle, increasing roughly linearly with vehicle height. Injection height of the dust plume is least important to long-range transport of PM 10 under unstable conditions and most important under stable atmospheric conditions.

  18. The Emission Effects by the Use of Biodiesel Fuel

    NASA Astrophysics Data System (ADS)

    Choi, Seung-Hun; Oh, Younhtaig

    The smoke emission of diesel engine is being recognized as the main cause for the serious air pollution related problem affecting our environment. In this study, we investigated the possibility of biodiesel fuel to reduce smoke emission as an alternative fuel for diesel engine. Additionally, gas chromatography was used to analyze not only total amount of HC(hydrocarbon) but also the amount of HC components from C1 to C6 in the exhaust gas to determine the exact source responsible for the remarkable reduction in the amount of smoke emission. Because biodiesel fuel has about 10 vol-% oxygen content, the combustion process of the diesel engine is improved and exhausted smoke emission density especially decreased.

  19. Potential climate engineering effectiveness and side effects during a high carbon dioxide-emission scenario

    NASA Astrophysics Data System (ADS)

    Keller, David P.; Feng, Ellias Y.; Oschlies, Andreas

    2014-02-01

    The realization that mitigation efforts to reduce carbon dioxide emissions have, until now, been relatively ineffective has led to an increasing interest in climate engineering as a possible means of preventing the potentially catastrophic consequences of climate change. While many studies have addressed the potential effectiveness of individual methods there have been few attempts to compare them. Here we use an Earth system model to compare the effectiveness and side effects of afforestation, artificial ocean upwelling, ocean iron fertilization, ocean alkalinization and solar radiation management during a high carbon dioxide-emission scenario. We find that even when applied continuously and at scales as large as currently deemed possible, all methods are, individually, either relatively ineffective with limited (<8%) warming reductions, or they have potentially severe side effects and cannot be stopped without causing rapid climate change. Our simulations suggest that the potential for these types of climate engineering to make up for failed mitigation may be very limited.

  20. Potential climate engineering effectiveness and side effects during a high carbon dioxide-emission scenario

    PubMed Central

    Keller, David P.; Feng, Ellias Y.; Oschlies, Andreas

    2014-01-01

    The realization that mitigation efforts to reduce carbon dioxide emissions have, until now, been relatively ineffective has led to an increasing interest in climate engineering as a possible means of preventing the potentially catastrophic consequences of climate change. While many studies have addressed the potential effectiveness of individual methods there have been few attempts to compare them. Here we use an Earth system model to compare the effectiveness and side effects of afforestation, artificial ocean upwelling, ocean iron fertilization, ocean alkalinization and solar radiation management during a high carbon dioxide-emission scenario. We find that even when applied continuously and at scales as large as currently deemed possible, all methods are, individually, either relatively ineffective with limited (<8%) warming reductions, or they have potentially severe side effects and cannot be stopped without causing rapid climate change. Our simulations suggest that the potential for these types of climate engineering to make up for failed mitigation may be very limited. PMID:24569320

  1. Potential climate engineering effectiveness and side effects during a high carbon dioxide-emission scenario.

    PubMed

    Keller, David P; Feng, Ellias Y; Oschlies, Andreas

    2014-02-25

    The realization that mitigation efforts to reduce carbon dioxide emissions have, until now, been relatively ineffective has led to an increasing interest in climate engineering as a possible means of preventing the potentially catastrophic consequences of climate change. While many studies have addressed the potential effectiveness of individual methods there have been few attempts to compare them. Here we use an Earth system model to compare the effectiveness and side effects of afforestation, artificial ocean upwelling, ocean iron fertilization, ocean alkalinization and solar radiation management during a high carbon dioxide-emission scenario. We find that even when applied continuously and at scales as large as currently deemed possible, all methods are, individually, either relatively ineffective with limited (<8%) warming reductions, or they have potentially severe side effects and cannot be stopped without causing rapid climate change. Our simulations suggest that the potential for these types of climate engineering to make up for failed mitigation may be very limited.

  2. [Effects of turning frequency on emission of greenhouse gas and ammonia during swine manure windrow composting].

    PubMed

    Zhao, Chen-Yang; Li, Hong-Mei; Wei, Yuan-Song; Zhong, Jia; Zheng, Jia-Xi; Han, Sheng-Hui; Wan, He-Feng

    2014-02-01

    It is of great concern for greenhouse gas (GHG) reduction of animal manure management in China due to the extreme lack of GHG emission data during animal manure composting. Therefore, the purpose of this study was to investigate the effects of turning frequency on the emission of GHG (CH4, N2O) and NH3 during swine manure windrow composting through on-site observation of a full scale test in Beijing. Results showed that the turning frequency had significant impacts on the emission of both GHG and ammonia, which did not only increase the emission of GHG and ammonia, but also increased the percentage of total nitrogen loss due to NH3 emission (42.2% at turning once a week and 70.05% at turning twice a week, respectively). Compared with N2O emission, CH4 emission was the main contributor to Global Warming Potentials (GWPs).

  3. 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.

  4. Effects of After-Treatment Control Technologies on Heavy-Duty Diesel Truck Emissions

    NASA Astrophysics Data System (ADS)

    Preble, C.; Dallmann, T. R.; Kreisberg, N. M.; Hering, S. V.; Harley, R.; Kirchstetter, T.

    2015-12-01

    Diesel engines are major emitters of nitrogen oxides (NOx) and the black carbon (BC) fraction of particulate matter (PM). Diesel particle filter (DPF) and selective catalytic reduction (SCR) emission control systems that target exhaust PM and NOx have recently become standard on new heavy-duty diesel trucks (HDDT). There is concern that DPFs may increase ultrafine particle (UFP) and total particle number (PN) emissions while reducing PM mass emissions. Also, the deliberate catalytic oxidation of engine-out NO to NO2 in continuously regenerating DPFs may lead to increased tailpipe emission of NO2 and near-roadway concentrations that exceed the 1-hr national ambient air quality standard. Increased NO2 emissions can also promote formation of ozone and secondary PM. We report results from ongoing on-road studies of HDDT emissions at the Port of Oakland and the Caldecott Tunnel in California's San Francisco Bay Area. Emission factors (g pollutant per kg diesel) were linked via recorded license plates to each truck's engine model year and installed emission controls. At both sites, DPF use significantly increased the NO2/NOx emission ratio. DPFs also significantly increased NO2 emissions when installed as retrofits on older trucks with higher baseline NOx emissions. While SCR systems on new trucks effectively reduce total NOx emissions and mitigate these undesirable DPF-related NO2 emissions, they also lead to significant emission of N2O, a potent greenhouse gas. When expressed on a CO2-equivalent basis, the N2O emissions increase offsets the fuel economy gain (i.e., the CO2 emission reduction) associated with SCR use. At the Port, average NOx, BC and PN emission factors from new trucks equipped with DPF and SCR were 69 ± 15%, 92 ± 32% and 66 ± 35% lower, respectively, than modern trucks without these emission controls. In contrast, at the Tunnel, PN emissions from older trucks retrofit with DPFs were ~2 times greater than modern trucks without DPFs. The difference

  5. Methane emission from rice fields: The effect of floodwater management

    NASA Astrophysics Data System (ADS)

    Sass, R. L.; Fisher, F. M.; Wang, Y. B.; Turner, F. T.; Jund, M. F.

    1992-09-01

    Rice fields emit methane and are important contributors to the increasing atmospheric CH4 concentration. Manipulation of rice floodwater may offer a means of mitigating methane emission from rice fields without reducing rice yields. To test methods for reducing methane emission, we applied four water management methods to rice fields planted on silty-clay soils near Beaumont, Texas. The four water treatments investigated were: normal permanent flood (46 days post planting), normal flood with mid- season drainage aeration, normal flood with multiple drainage aeration, and late flood (76 days post planting). Methane emission rates varied markedly with water regime, showing the lowest seasonal total emission (1.2 g m-2) with a multiple-aeration treatment and the highest (14.9 g m-2) with a late flood. Although the multiple- aeration water management treatment emitted 88% less methane than the normal irrigation treatment and did not reduce rice yields, the multiple-aeration treatment did require 2.7 times more water than the 202 mm required by the normal floodwater treatment. A comparison of measured methane emission and production rates obtained from incubated soil cores indicated that, depending on time of season and flood condition, from zero to over 90% of the methane produced was oxidized. The average amount of methane which was oxidized during times of high emission was 73.1 ± 13.7 percent of that produced.

  6. Effect of Friction Testing of Metals on Particle Emission

    NASA Astrophysics Data System (ADS)

    Kouam, J.; Songmene, V.; Djebara, A.; Khettabi, R.

    2012-06-01

    Metallic particles emitted during manufacturing processes can represent a serious danger for occupational safety. The mechanisms responsible for these particle emissions include two- and three-body frictions; Moreover, such particles can also be emitted during several other processes, including mechanical braking. To be in a position to devise ways to reduce these particle emissions at the source, it is important to know their size, quantity, and distribution, as well as the relationships between operating conditions and particle emissions. This article investigates nanoparticle and microparticle emissions during two friction tests: one (setup 1: pin in rotation only) simulates the friction occurring during mechanical braking actions, and another (setup 2: pin in rotation and translation) simulates the friction taking place at the tool-workpiece interface during metal cutting processes. The materials tested were aluminum alloys (6061-T6 and 7075-T6), and the pin used was a carbide cylinder. Particle emission was monitored using the Scanning Mobility Particle Sizer (SMPS) for nanoparticles, and the Aerosol Particle Sizer (APS) for microparticles. It was found that friction produces more nanoparticles than microparticles, and that total particle emission can be reduced by operating at low or at high sliding speeds.

  7. Effects of changing lawn care practices on N2O emissions: A scenario analysis

    NASA Astrophysics Data System (ADS)

    Crane, J. W.; Hornberger, G. M.

    2013-12-01

    Lawn soil emissions of N2O are controlled by a variety of factors, among them the varied lawn care practices employed by homeowners or lawn care professionals. Frequency, intensity, and timing of fertilizer application and irrigation all place controls on soil N2O emissions produced as an intermediary of both nitrification and denitrification. We use a process-based biogeochemical model of C and N dynamics to determine how modifying these lawn care practices affect N2O emissions from lawn soils in Nashville, TN. Closed chamber sampling of N2O emissions is used to calibrate the model and provide a base case allowing additional scenarios to be run. We show that seasonal timing of fertilizer application strongly drives the magnitude of N2O emissions, with early summer application effectively doubling these emissions with no changes to other lawn care practices. Decreasing N fertilizer application intensity causes a fairly direct decrease in N2O emissions, while the frequency of fertilizer applications does not have a so clearly direct impact. Irrigation practices also place controls on N2O emissions, as frequent, intense irrigation increases soil moisture, creates anoxic conditions in the soil and results in elevated N2O emissions. These results suggest that understanding how lawn care affects N2O emissions from lawn soils could provide simple guidelines for lawn care that could substantively reduce lawn N2O emissions.

  8. Inhaled Diesel Emissions Generated with Cerium Oxide Nanoparticle Fuel Additive Induce Adverse Pulmonary and Systemic Effects

    EPA Science Inventory

    Diesel exhaust (DE) exposure induces adverse cardiopulmonary effects. Cerium oxide nanoparticles added to diesel fuel (DECe) increases fuel burning efficiency but leads to altered emission characteristics and potentially altered health effects. Here, we evaluated whether DECe res...

  9. Effects of grain boundary characteristics of steel on magnetoacoustic emission spectra

    NASA Technical Reports Server (NTRS)

    Namkung, M.; Yost, W. T.; Utrata, D.; Grainger, J. L.; Kushnick, P. W.

    1989-01-01

    Consideration is given to the effects of grain boundary characteristics on the properties of a magnetoacoustic emission spectra obtained by external ac magnetic field-driven domain wall motions. In studies with HY80 steel samples, it is found that the domain wall-defect interaction enhances as more grain boundary is introduced. The enhancement of the domain wall-defect interaction generates high amplitude magnetoacoustic emission pulses and reduces the rate of magnetoacoustic emission events by limiting domain wall motions.

  10. Fuel composition effects on natural gas vehicle emissions

    SciTech Connect

    Blazek, C.F.; Grimes, J.; Freeman, P.; Bailey, B.K.; Colucci, C.

    1994-09-01

    Under a contract from DOE`s National Renewable Energy Laboratory (NREL) and support from Brooklyn Union Gas Company (BUG), Northern Illinois Gas Co., the Institute of Gas Technology (IGT) evaluated four state-of-the-art, electronic, closed-loop natural gas vehicle (NGV) conversion systems. The systems included an Impco electronic closed-loop system, Mogas electronic closed-loop system, Stewart and Stevenson`s GFI system, and an Automotive Natural Gas Inc. (ANGI) Level 1 electronic closed-loop conversion system. Conversion system evaluation included emission testing per 40 CFR Part 86, and driveability. All testing was performed with a 1993 Chevy Lumina equipped with a 3.1 liter MPFI V6 engine. Each system was emission tested using three different certified compositions of natural gas, representing the 10th, mean and 90th percentile gas compositions distributed in the United States. Emission testing on indolene was performed prior to conversion kit testing to establish a base emission value. Indolene testing was also performed at the end of the project when the vehicle was converted to its OEM configuration to ensure that the vehicle`s emissions were not altered during testing. The results of these tests will be presented.

  11. Effects of nitrogen fertilizer application on greenhouse gas emissions and economics of corn production.

    PubMed

    Kim, Seungdo; Dale, Bruce E

    2008-08-15

    Nitrogen fertilizer plays an important role in corn cultivation in terms of both economic and environmental aspects. Nitrogen fertilizer positively affects corn yield and the soil organic carbon level, but it also has negative environmental effects through nitrogen-related emissions from soil (e.g., N20, NOx, NO3(-) leaching, etc.). Effects of nitrogen fertilizer on greenhouse gas emissions associated with corn grain are investigated via life cycle assessment. Ecoefficiency analysis is also used to determine an economically and environmentally optimal nitrogen application rate (NAR). The ecoefficiency index in this study is defined as the ratio of economic return due to nitrogen fertilizer to the greenhouse gas emissions of corn cultivation. Greenhouse gas emissions associated with corn grain decrease as NAR increases at a lower NAR until a minimum greenhouse gas emission level is reached because corn yield and soil organic carbon level increase with NAR. Further increasing NAR after a minimum greenhouse gas emission level raises greenhouse gas emissions associated with corn grain. Increased greenhouse gas emissions of corn grain due to nitrous oxide emissions from soil are much higher than reductions of greenhouse gas emissions of corn grain due to corn yield and changes in soil organic carbon levels at a higher NAR. Thus, there exists an environmentally optimal NAR in terms of greenhouse gas emissions. The trends of the ecoefficiency index are similar to those of economic return to nitrogen and greenhouse gas emissions associated with corn grain. Therefore, an appropriate NAR could enhance profitability as well as reduce greenhouse gas emissions associated with corn grain.

  12. Modeling the effects of atmospheric emissions on groundwater composition

    SciTech Connect

    Brown, Theresa Jean

    1994-01-01

    A composite model of atmospheric, unsaturated and groundwater transport is developed to evaluate the processes determining the distribution of atmospherically derived contaminants in groundwater systems and to test the sensitivity of simulated contaminant concentrations to input parameters and model linkages. One application is to screen specific atmospheric emissions for their potential in determining groundwater age. Temporal changes in atmospheric emissions could provide a recognizable pattern in the groundwater system. The model also provides a way for quantifying the significance of uncertainties in the tracer source term and transport parameters on the contaminant distribution in the groundwater system, an essential step in using the distribution of contaminants from local, point source atmospheric emissions to examine conceptual models of groundwater flow and transport.

  13. An Effective Secondary Electron Emission Suppression Treatment For Copper MDC

    NASA Technical Reports Server (NTRS)

    Curren, Arthur N.; Long, Kenwyn J.; Jensen, Kenneth A.; Roman, Robert F.

    1993-01-01

    Untreated oxygen-free, high-conductivity (OFHC) copper, commonly used for MDC electrodes, exhibits relatively high secondary electron emission characteristics. This paper describes a specialized ion-bombardment procedure for texturing copper surfaces which sharply reduces the emission properties relative to untreated copper. The resulting surface is a particle-free, robust, uniformly highly-textured all-metal structure. The use of this process requires no modifications to copper machining, brazing, or other MDC normal fabrication procedures. The flight TWT for a planned NASA deep space probe, the Cassini Mission, will incorporate copper MDC electrodes treated with the method described here.

  14. Effects of methanol-containing additive on emission characteristics from a heavy-duty diesel engine.

    PubMed

    Chao, M R; Lin, T C; Chao, H R; Chang, F H; Chen, C B

    2001-11-12

    This study was aimed to investigate the effect of methanol-containing additive (MCA) on the regulated emissions of hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx), particulate matter (PM), as well as the unregulated carbon dioxide (CO2) and polycyclic aromatic hydrocarbons (PAHs) from a diesel engine. The engine was tested on a series of diesel fuels blended with five additive levels (0, 5, 8, 10 and 15% of MCA by volume). Emissions tests were performed under both cold- and hot-start transient heavy-duty federal test procedure (HD-FTP) cycles and two selected steady-state modes. Results show that MCA addition slightly decreases PM emissions but generally increases both THC and CO emissions. Decrease in NOx emissions was found common in all MCA blends. As for unregulated emissions, CO2 emissions did not change significantly for all MCA blends, while vapor-phase and particle-associated PAHs emissions in high load and transient cycle tests were relatively low compared to the base diesel when either 5 or 8% MCA was used. This may be attributed to the lower PAHs levels in MCA blends. Finally, the particle-associated PAHs emissions also showed trends quite similar to that of the PM emissions in this study.

  15. Large increases in Arctic biogenic volatile emissions are a direct effect of warming

    NASA Astrophysics Data System (ADS)

    Kramshøj, Magnus; Vedel-Petersen, Ida; Schollert, Michelle; Rinnan, Åsmund; Nymand, Josephine; Ro-Poulsen, Helge; Rinnan, Riikka

    2016-05-01

    Biogenic volatile organic compounds are reactive gases that can contribute to atmospheric aerosol formation. Their emission from vegetation is dependent on temperature and light availability. Increasing temperature, changing cloud cover and shifting composition of vegetation communities can be expected to affect emissions in the Arctic, where the ongoing climate changes are particularly severe. Here we present biogenic volatile organic compound emission data from Arctic tundra exposed to six years of experimental warming or reduced sunlight treatment in a randomized block design. By separately assessing the emission response of the whole ecosystem, plant shoots and soil in four measurements covering the growing season, we have identified that warming increased the emissions directly rather than via a change in the plant biomass and species composition. Warming caused a 260% increase in total emission rate for the ecosystem and a 90% increase in emission rates for plants, while having no effect on soil emissions. Compared to the control, reduced sunlight decreased emissions by 69% for the ecosystem, 61-65% for plants and 78% for soil. The detected strong emission response is considerably higher than observed at more southern latitudes, emphasizing the high temperature sensitivity of ecosystem processes in the changing Arctic.

  16. Effect of enhanced leachate recirculated (ELR) landfill operation and gas extraction on greenhouse gas emissions

    NASA Astrophysics Data System (ADS)

    Samir, Sonia

    The bioreactor/ enhanced leachate recirculated (ELR) landfill operation with the addition of moisture/ leachate to the landfill, accelerate the process of landfill waste decomposition; and increase the generation of LFG over a shorter period of time. Since emissions from the landfills are directly related to the gas generation, the increase in gas generation might also increase the emission from the landfill. On the contrary, the presence of gas extraction is suggested to mitigate the fugitive emissions from the landfills. Therefore, the motivation of the current study was to evaluate the effect of ELR operation as well as the gas extraction on the greenhouse gas emissions from the landfill. The current study was conducted in the City of Denton Landfill, Texas. Methane emission was investigated using a portable FID and static flux chamber technique from the landfill surface. Emission was measured from an ELR operated cell (cell 2) as well as a conventional cell (cell 0) in the City of Denton Landfill. Methane emission for cell 2 varied from 9544.3 ppm to 0 ppm while for cell 0, it varied from 0 ppm to 47 ppm. High spatial variations were observed during monitoring from both cells 0 and cell 2 which could be recognized as the variation of gas generation below the cover soil. The comparison between emissions from the slope and surface of the landfill showed that more methane emission occurred from the slopes than the top surface. In addition, the average landfill emission showed an increasing trend with increase in temperature and decreasing trend with increasing precipitation. The effect of ELR operation near the recirculation pipes showed a lag period between the recirculation and the maximum emission near the pipe. The emission near the pipe decreased after 1 day of recirculation and after the initial decrease, the emission started to increase and continued to increase up to 7 days after the recirculation. However, approximately after 10 days of recirculation, the

  17. On the effect of surface emissivity on temperature retrievals. [for meteorology

    NASA Technical Reports Server (NTRS)

    Kornfield, J.; Susskind, J.

    1977-01-01

    The paper is concerned with errors in temperature retrieval caused by incorrectly assuming that surface emissivity is equal to unity. An error equation that applies to present-day atmospheric temperature sounders is derived, and the bias errors resulting from various emissivity discrepancies are calculated. A model of downward flux is presented and used to determine the effective downward flux. In the 3.7-micron region of the spectrum, emissivities of 0.6 to 0.9 have been observed over land. At a surface temperature of 290 K, if the true emissivity is 0.6 and unit emissivity is assumed, the error would be approximately 11 C. In the 11-micron region, the maximum deviation of the surface emissivity from unity was 0.05.

  18. The effect of nitrogen fertilization on the COS and CS2 emissions from temperature forest soils

    NASA Astrophysics Data System (ADS)

    Melillo, Jerry M.; Steudler, Paul A.

    1989-11-01

    The net fluxes of carbonyl sulfide (COS) and CS2 to the atmosphere from nitrogen amended and unamended deciduous and coniferous forest soils were measured during the spring of 1986. It was found that emissions of these gases from acidic forest soils were substantially increased after nitrogen fertilization. The total (COS + CS2) emissions were increased by nearly a factor of three in the hardwood stand and were more than doubled in the pine stand. Furthermore, vegetation type appeared to have an influence on which was the dominant sulfur gas released from the forest soils. The added nitrogen caused a dramatic increase in COS emissions from the hardwood stand (a factor of 3 increase), while CS2 emissions from this site were not affected. The opposite response was observed in the pine stand; that is, the nitrogen fertilization had no effect on COS emissions, but did stimulate CS2 emissions (a factor of more than 9 increase).

  19. Are renewables portfolio standards cost-effective emission abatement policy?

    PubMed

    Dobesova, Katerina; Apt, Jay; Lave, Lester B

    2005-11-15

    Renewables portfolio standards (RPS) could be an important policy instrument for 3P and 4P control. We examine the costs of renewable power, accounting for the federal production tax credit, the market value of a renewable credit, and the value of producing electricity without emissions of SO2, NOx, mercury, and CO2. We focus on Texas, which has a large RPS and is the largest U.S. electricity producer and one of the largest emitters of pollutants and CO2. We estimate the private and social costs of wind generation in an RPS compared with the current cost of fossil generation, accounting for the pollution and CO2 emissions. We find that society paid about 5.7 cent/kWh more for wind power, counting the additional generation, transmission, intermittency, and other costs. The higher cost includes credits amounting to 1.1 cent/kWh in reduced SO2, NOx, and Hg emissions. These pollution reductions and lower CO2 emissions could be attained at about the same cost using pulverized coal (PC) or natural gas combined cycle (NGCC) plants with carbon capture and sequestration (CCS); the reductions could be obtained more cheaply with an integrated coal gasification combined cycle (IGCC) plant with CCS.

  20. Potential Cost-Effective Opportunities for Methane Emission Abatement

    SciTech Connect

    Warner, Ethan; Steinberg, Daniel; Hodson, Elke; Heath, Garvin

    2015-08-01

    The energy sector was responsible for approximately 84% of carbon dioxide equivalent (CO2e) greenhouse gas (GHG) emissions in the U.S. in 2012 (EPA 2014a). Methane is the second most important GHG, contributing 9% of total U.S. CO2e emissions. A large portion of those methane emissions result from energy production and use; the natural gas, coal, and oil industries produce approximately 39% of anthropogenic methane emissions in the U.S. As a result, fossil-fuel systems have been consistently identified as high priority sectors to contribute to U.S. GHG reduction goals (White House 2015). Only two studies have recently attempted to quantify the abatement potential and cost associated with the breadth of opportunities to reduce GHG emissions within natural gas, oil, and coal supply chains in the United States, namely the U.S. Environmental Protection Agency (EPA) (2013a) and ICF (2014). EPA, in its 2013 analysis, estimated the marginal cost of abatement for non-CO2 GHG emissions from the natural gas, oil, and coal supply chains for multiple regions globally, including the United States. Building on this work, ICF International (ICF) (2014) provided an update and re-analysis of the potential opportunities in U.S. natural gas and oil systems. In this report we synthesize these previously published estimates as well as incorporate additional data provided by ICF to provide a comprehensive national analysis of methane abatement opportunities and their associated costs across the natural gas, oil, and coal supply chains. Results are presented as a suite of marginal abatement cost curves (MACCs), which depict the total potential and cost of reducing emissions through different abatement measures. We report results by sector (natural gas, oil, and coal) and by supply chain segment - production, gathering and boosting, processing, transmission and storage, or distribution - to facilitate identification of which sectors and supply chain

  1. Regularities of acoustic emission and thermoemission memory effect in coal specimens under varying thermal conditions

    SciTech Connect

    Shkuratnik, V.L.; Kuchurin, S.V.; Vinnikov, V.A.

    2007-07-15

    The experimental data on acoustic emission regularities are presented for specimens of different genetic coal types exposed to a wide range of cyclic heating modes. Peculiarities of formation and manifestation of thermal-emission memory effect depending on amplitude and duration of the thermal-field action are revealed.

  2. Rye cover crop effects on nitrous oxide emissions from a corn-soybean system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural activities are a major source nitrous oxide emitted to the atmosphere. Development of management practices to reduce these emissions is needed. Non-leguminous cover crops are efficient scavengers of residual soil nitrate, but their effects on nitrous oxide emissions have not been well d...

  3. The effect of gasoline RVP on exhaust emissions from current European vehicles

    SciTech Connect

    Bennett, P.J.; Beckwith, P.; Goodfellow, C.L.; Skaardalsmo, K.

    1995-12-31

    The effect of gasoline RVP on regulated exhaust emissions has been investigated in a fleet consisting of five current European vehicles. The effects of MTBE with changing RVP and E70 were also studied. All vehicles were equipped with the standard OEM small carbon canisters and three-way catalytic converters and the regulated emissions measured over the new European test cycle. A rigorous refueling protocol was employed to ensure that the carbon canisters were loaded in a repeatable way before the emission tests. The results show that a reduction in RVP gave benefits in CO and NOx, but no effect on exhaust THC emissions. The benefits for CO and NOx were greater in non-oxygenated fuels. Of the five test vehicles, three showed CO emission benefits due to RVP reduction, while CO from the other two was insensitive to RVP changes. Four vehicles also showed NOx emission benefits due to RVP reduction while the NOx emissions from the other vehicle were insensitive to RVP changes. The benefits of reducing RVP were observed for the fleet over all three phases of the cycle, however, the largest percentage of changes were seen after the vehicles had warmed up. Although no significant overall effect of RVP on exhaust THC emissions was apparent, reductions in THC over the ECE 3+4 and EUDC phases were observed. At high RVP MTBE addition gave reductions in CO and NOx emissions, but at low RVP no emission reductions were observed. A reduction in E70 only influenced exhaust THC emissions, resulting in a small increase.

  4. Drought and soil amendment effects on monoterpene emission in rosemary plants.

    PubMed

    Nogués, I; Muzzini, V; Loreto, F; Bustamante, M A

    2015-12-15

    The aim of this work was to study the changes during 15days in the monoterpene emission rates of the Mediterranean shrub rosemary (Rosmarinus officinalis L.), in response to increasing drought stress and fertilisation using two different composts derived from livestock anaerobic digestates (cattle and pig slurry). Drought stress considerably reduced photosynthetic rates, stomatal conductance and isoprenoid emissions and also induced a change in blend composition. In the drought stressed rosemary plants, a positive relationship of non-oxygenated monoterpene emissions and a negative relationship of oxygenated monoterpene with photosynthesis were observed, indicating a different control mechanism over the emissions of the two types of isoprenoids. The emission of non-oxygenated monoterpenes seemed to depend more on photosynthesis and "de novo" synthesis, whereas emission of oxygenate monoterpenes was more dependent on volatilisation from storage, mainly driven by cumulative temperatures. In the short term, the addition of composted organic materials to the soil did not induce a significant effect on isoprenoid emission rates in the rosemary plants. However, the effect of the interaction between fertilisation and seasonality on isoprenoid emission rates was influenced by the amendment origin. Also, we emphasized changes in potential isoprenoid emission factors throughout the experiment, probably indicating changes in the leaf developmental stage.

  5. ERRATUM: Effective emissivity of a cylindrical cavity with an inclined bottom: I. Isothermal cavity Effective emissivity of a cylindrical cavity with an inclined bottom: I. Isothermal cavity

    NASA Astrophysics Data System (ADS)

    Prokhorov, Alexander V.; Hanssen, Leonard M.

    2009-12-01

    In table 2 of this paper, the values of the normal effective emissivity are presented, instead of values of the hemispherical effective emissivity for an isothermal cavity with β = 30°. Here, we present the corrected portion of table 2. Also, in figure 5 (right-side plot) and figure 6 (left column, second row), instead of a cavity with β = 58°, the plots for a cavity with slightly different geometric parameters are shown. We show here the corrected map of reflections and a three-dimensional plot of the distribution of the local normal effective emissivity. The corrected portions of table 2, figure 5 and figure 6 are given in the pdf file.

  6. FUEL FORMULATION EFFECTS ON DIESEL FUEL INJECTION, COMBUSTION, EMISSIONS AND EMISSION CONTROL

    SciTech Connect

    Boehman, A; Alam, M; Song, J; Acharya, R; Szybist, J; Zello, V; Miller, K

    2003-08-24

    This paper describes work under a U.S. DOE sponsored Ultra Clean Fuels project entitled ''Ultra Clean Fuels from Natural Gas,'' Cooperative Agreement No. DE-FC26-01NT41098. In this study we have examined the incremental benefits of moving from low sulfur diesel fuel and ultra low sulfur diesel fuel to an ultra clean fuel, Fischer-Tropsch diesel fuel produced from natural gas. Blending with biodiesel, B100, was also considered. The impact of fuel formulation on fuel injection timing, bulk modulus of compressibility, in-cylinder combustion processes, gaseous and particulate emissions, DPF regeneration temperature and urea-SCR NOx control has been examined. The primary test engine is a 5.9L Cummins ISB, which has been instrumented for in-cylinder combustion analysis and in-cylinder visualization with an engine videoscope. A single-cylinder engine has also been used to examine in detail the impacts of fuel formulation on injection timing in a pump-line-nozzle fueling system, to assist in the interpretation of results from the ISB engine.

  7. Effect of E85 on Tailpipe Emissions from Light-Duty Vehicles

    SciTech Connect

    Yanowitz, J.; McCormick, R. L.

    2009-02-01

    E85, which consists of nominally 85% fuel grade ethanol and 15% gasoline, must be used in flexible-fuel (or 'flexfuel') vehicles (FFVs) that can operate on fuel with an ethanol content of 0-85%. Published studies include measurements of the effect of E85 on tailpipe emissions for Tier 1 and older vehicles. Car manufacturers have also supplied a large body of FFV certification data to the U.S. Environmental Protection Agency, primarily on Tier 2 vehicles. These studies and certification data reveal wide variability in the effects of E85 on emissions from different vehicles. Comparing Tier 1 FFVs running on E85 to similar non-FFVs running on gasoline showed, on average, significant reductions in emissions of oxides of nitrogen (NOx; 54%), non-methane hydrocarbons (NMHCs; 27%), and carbon monoxide (CO; 18%) for E85. Comparing Tier 2 FFVs running on E85 and comparable non-FFVs running on gasoline shows, for E85 on average, a significant reduction in emissions of CO (20%), and no significant effect on emissions of non-methane organic gases (NMOGs). NOx emissions from Tier 2 FFVs averaged approximately 28% less than comparable non-FFVs. However, perhaps because of the wide range of Tier 2 NOx standards, the absolute difference in NOx emissions between Tier 2 FFVs and non-FFVs is not significant (P 0.28). It is interesting that Tier 2 FFVs operating on gasoline produced approximately 13% less NMOGs than non-FFVs operating on gasoline. The data for Tier 1 vehicles show that E85 will cause significant reductions in emissions of benzene and butadiene, and significant increases in emissions of formaldehyde and acetaldehyde, in comparison to emissions from gasoline in both FFVs and non-FFVs. The compound that makes up the largest proportion of organic emissions from E85-fueled FFVs is ethanol.

  8. Effect of Background Emissivity on Gas Detection in Thermal Hyperspectral Imagery

    SciTech Connect

    Walsh, Stephen J.; Tardiff, Mark F.; Chilton, Lawrence K.; Metoyer, Candace N.

    2008-10-02

    Detecting and identifying weak gaseous plumes using thermal imaging data is complicated by many factors. These include variability due to atmosphere, ground and plume temper- ature, and background clutter. This paper presents an analysis of one formulation of the physics-based radiance model, which describes at-sensor observed radiance. The background emissivity and plume/ground temperatures are isolated, and their effects on net chemical signal are described. This analysis shows that the plume’s physical state, emission or absorption, is directly dependent on the background emissivity. It then describes what conditions on the background emissivity have inhibiting effects on the net chemical signal. These claims are illustrated by analyzing synthetic hyperspectral imaging data with the Adaptive Matched Filter using four chemicals and three distinct background emissivities. Two chemicals (Carbontetrachloride and Tetraflourosilane) in the analysis had a very strong relationship with the background emissivities: they exhibited absorbance over a small range of wavenumbers and the background emissivities showed a consistent ordering at these wavenumbers. Analysis of simulated hyperspectral images containing these chemicals showed complete agreement with the analysis of the physics-based model that described when the background emissivities would have inhibiting effects on gas detection. The other chemicals considered (Ammonia and Tributylphosphate) exhibited very complex absorbance structure across the longwave infrared spectrum. Analysis of images containing these chemicals revealed that the the analysis of the physics-based model did not hold completely for these complex chemicals but did suggest that gas detection was dominated by their dominant absorbance features. These results provide some explanation of the effect of the background emissivity on gas detection and a more general exploration of gas absorbance/background emissivity variability and their effects on

  9. [Effects of superphosphate addition on NH3 and greenhouse gas emissions during vegetable waste composting].

    PubMed

    Yang, Yan; Sun, Qin-ping; Li, Ni; Liu, Chun-sheng; Li, Ji-jin; Liu, Ben-sheng; Zou, Guo-yuan

    2015-01-01

    To study the effects of superphosphate (SP) on the NH, and greenhouse gas emissions, vegetable waste composting was performed for 27 days using 6 different treatments. In addition to the controls, five vegetable waste mixtures (0.77 m3 each) were treated with different amounts of the SP additive, namely, 5%, 10%, 15%, 20% and 25%. The ammonia volatilization loss and greenhouse gas emissions were measured during composting. Results indicated that the SP additive significantly decreased the ammonia volatilization and greenhouse gas emissions during vegetable waste composting. The additive reduced the total NH3 emission by 4.0% to 16.7%. The total greenhouse gas emissions (CO2-eq) of all treatments with SP additives were decreased by 10.2% to 20.8%, as compared with the controls. The NH3 emission during vegetable waste composting had the highest contribution to the greenhouse effect caused by the four different gases. The amount of NH3 (CO2-eq) from each treatment ranged from 59.90 kg . t-1 to 81.58 kg . t-1; NH3(CO2-eq) accounted for 69% to 77% of the total emissions from the four gases. Therefore, SP is a cost-effective phosphorus-based fertilizer that can be used as an additive during vegetable waste composting to reduce the NH3 and greenhouse gas emissions as well as to improve the value of compost as a fertilizer.

  10. Development of an improved urban emissivity model based on sky view factor for retrieving effective emissivity and surface temperature over urban areas

    NASA Astrophysics Data System (ADS)

    Yang, Jinxin; Wong, Man Sing; Menenti, Massimo; Nichol, Janet; Voogt, James; Krayenhoff, E. Scott; Chan, P. W.

    2016-12-01

    This study aims to evaluate the effects of urban geometry on retrieval of emissivity and surface temperature in urban areas. An improved urban emissivity model based on sky view factor (IUEM-SVF) was further enhanced to consider all radiance contributions leaving the urban canopy, including (i) emission by all facets within an instantaneous field of view (IFOV); (ii) reflection by all facets of emission from surrounding facets; and (iii) propagation of emitted and reflected radiation with multiple reflections (scattering) within a complex 3D array of urban objects. The effective emissivity derived from IUEM-SVF was evaluated with a microscale radiative transfer and energy balance model: Temperatures of Urban Facets in 3-D (TUF-3D). IUEM-SVF performs well when urban facets have uniform emissivity and temperature; e.g., root mean square deviations (RMSD) are less than 0.005 when material emissivity is larger than 0.80 (ɛ ⩾ 0.80). However, when material emissivities are variable within the observed target, differences of effective emissivity between IUEM-SVF and TUF-3D become larger, e.g., RMSD of 0.010. When the effect of geometry is not considered and a mixed pixel emissivity is defined, the difference is even much larger (i.e. 0.02) and this difference increases with the decrease of sky view factor. Thus, the geometry effect should be considered in the determination of effective emissivity. Effective emissivity derived from IUEM-SVF was used to retrieve urban surface temperature from a nighttime ASTER thermal infrared image. Promising results were achieved in comparison with standard LST products retrieved with the Temperature and Emissivity Separation (TES) algorithm. IUEM-SVF shows promise as a means to improve the accuracy of urban surface temperature retrieval. The effect of thermal heterogeneity on the effective emissivity was also evaluated by TUF-3D, and results show that the thermal heterogeneity cannot be neglected since the RMSD between the effective

  11. Temperature and moisture effect on spore emission in the fungal biofiltration of hydrophobic VOCs.

    PubMed

    Vergara-Fernández, Alberto; Salgado-Ísmodes, Vanida; Pino, Miguel; Hernández, Sergio; Revah, Sergio

    2012-01-01

    The effect of temperature and moisture on the elimination capacity (EC), CO(2) production and spore emission by Fusarium solani was studied in biofilters packed with vermiculite and fed with n- pentane. Three temperatures (15, 25 and 35°C) were tested and the highest average EC (64 g m(-3) h(-1)) and lower emission of spores (2.0 × 10(3) CFU m(-3) air) were obtained at 25°C. The effect of moisture content of the packing material indicates that the highest EC (65 g m(-3) h(-1)) was obtained at 50 % moisture. However, lowest emission (1.3 × 10(3) CFU m(-3) air) was obtained at 80 % moisture. Furthermore, the results show that a slight decrease in spore emission was found with increasing moisture content. In all cases, the depletion of the nitrogen source in the biofilter induced the sporulation, a decay of the EC and increased spore emission.

  12. Simulations of Surface Effects and Electron Emission from Diamond-Amplifier Cathodes

    SciTech Connect

    Dimitrov D. A.; Rao T.; Busby, R.; Smithe, D.; Cary, J.R.; Ben-Zvi, I.; Chang, X.; Smedley, J.; Wu, Q.; Wang, E.

    2011-09-30

    Emission of electrons in diamond experiments based on the promising diamond-amplifier concept was recently demonstrated. Transmission mode experiments have shown the potential to realize over two orders of magnitude charge amplification. However, the recent emission experiments indicate that surface effects should be understood in detail to build cathodes with optimal properties. We have made progress in understanding secondary electron generation and charge transport in diamond with models we implemented in the VORPAL particle-in-cell computational framework. We introduce models that we have been implementing for surface effects (band bending and electron affinity), charge trapping, and electron emission from diamond. Then, we present results from 3D VORPAL diamond-vacuum simulations with the integrated capabilities on generating electrons and holes, initiated by energetic primary electrons, charge transport, and then emission of electrons from diamond into vacuum. Finally, we discuss simulation results on the dependence of the electron emission on diamond surface properties.

  13. The effects of temperature on supersonic jet noise emission

    NASA Technical Reports Server (NTRS)

    Seiner, John M.; Ponton, Michael K.; Jansen, Bernard J.; Lagen, Nicholas T.

    1992-01-01

    This paper examines the generation of sound produced by high temperature supersonic jets. In particular, the question of the importance of supersonic instability waves to noise emission is considered relative to the role of Kelvin-Helmholtz (K-H) instability waves. Here, these waves are taken to be synonymous with the Mach emission process. Jet total temperatures from 313 to 1534 K are investigated using an axisymmetric water cooled supersonic nozzle designed for Mach 2. The aerodynamic and acoustic results of this study indicate that the dominant noise contributors are the K-H waves over the entire temperature range. Good agreement between measured and numerically predicted plume properties are obtained and an elliptic nozzle is used to demonstrate reduction of the K-H waves.

  14. Particle Emission and Charging Effects Induced by Fracture

    DTIC Science & Technology

    1989-06-15

    recombination with mobile charge carriers). These processes are initiated by bond breaking resulting in the creation of localized departures from...subsequendy decay to yield after-emission. Thermally stimulated relaxation involving mobile charge carriers releasing energy at appropriate recombination...region of contact. This flow of charge is slow because of the poor charge mobility in the rubber. In addition, any oxide layer on the metal also

  15. Effects on carbon and nitrogen emissions due to swine manure removal for biofuel production.

    PubMed

    Weaver, Kim H; Harper, Lowry A; Brown, Sarah M

    2012-01-01

    Methane (CH) and ammonia (NH) are emitted from swine-manure processing lagoons, contributing to global climate change and reducing air quality. Manure diverted to biofuel production is proposed as a means to reduce CH emissions. At a swine confined animal feeding operation in the U.S. Central Great Basin, animal manure was diverted from 12 farms to a biofuel facility and converted to methanol. Ammonia emissions were determined using the De Visscher Model from measured data of dissolved lagoon ammoniacal N concentrations, pH, temperature, and wind speed at the lagoon sites. Other lagoon gas emissions were measured with subsurface gas collection devices and gas chromatography analysis. During 2 yr of study, CO and CH emissions from the primary lagoons decreased 11 and 12%, respectfully, as a result of the biofuel process, compared with concurrently measured control lagoon emissions. Ammonia emissions increased 47% compared with control lagoons. The reduction of CH and increase in NH emissions agrees with a short-term study measured at this location by Lagrangian inverse dispersion analysis. The increase in NH emissions was primarily due to an increase in lagoon solution pH attributable to decreased methanogenesis. Also observed due to biofuel production was a 20% decrease in conversion of total ammoniacal N to N, a secondary process for the removal of N in anaerobic waste lagoons. The increase in NH emissions can be partially attributed to the decrease in N production by a proposed NH conversion to N mechanism. This mechanism predicts that a decrease in NH conversion to N increases ammoniacal N pH. Both effects increase NH emissions. It is unknown whether the decrease in NH conversion to N is a direct or physical result of the decrease in methanogenesis. Procedures and practices intended to reduce emissions of one pollutant can have an unintended consequence on the emissions of another pollutant.

  16. Effects of Headspace and Oxygen Level on Off-gas Emissions from Wood Pellets in Storage

    SciTech Connect

    Sokhansanj, Shahabaddine; Kuang, Xingya; Shankar, T.S.; Lim, C. Jim; Bi, X.T.; Melin, Staffan

    2009-10-01

    Few papers have been published in the open literature on the emissions from biomass fuels, including wood pellets, during the storage and transportation and their potential health impacts. The purpose of this study is to provide data on the concentrations, emission factors, and emission rate factors of CO2, CO, and CH4 from wood pellets stored with different headspace to container volume ratios with different initial oxygen levels, in order to develop methods to reduce the toxic off-gas emissions and accumulation in storage spaces. Metal containers (45 l, 305 mm diameter by 610 mm long) were used to study the effect of headspace and oxygen levels on the off-gas emissions from wood pellets. Concentrations of CO2, CO, and CH4 in the headspace were measured using a gas chromatograph as a function of storage time. The results showed that the ratio of the headspace ratios and initial oxygen levels in the storage space significantly affected the off-gas emissions from wood pellets stored in a sealed container. Higher peak emission factors and higher emission rates are associated with higher headspace ratios. Lower emissions of CO2 and CO were generated at room temperature under lower oxygen levels, whereas CH4 emission is insensitive to the oxygen level. Replacing oxygen with inert gases in the storage space is thus a potentially effective method to reduce the biomass degradation and toxic off-gas emissions. The proper ventilation of the storage space can also be used to maintain a high oxygen level and low concentrations of toxic off-gassing compounds in the storage space, which is especially useful during the loading and unloading operations to control the hazards associated with the storage and transportation of wood pellets.

  17. Effects of headspace and oxygen level on off-gas emissions from wood pellets in storage.

    PubMed

    Kuang, Xingya; Shankar, Tumuluru Jaya; Sokhansanj, Shahab; Lim, C Jim; Bi, Xiaotao T; Melin, Staffan

    2009-11-01

    Few papers have been published in the open literature on the emissions from biomass fuels, including wood pellets, during the storage and transportation and their potential health impacts. The purpose of this study is to provide data on the concentrations, emission factors, and emission rate factors of CO(2), CO, and CH(4) from wood pellets stored with different headspace to container volume ratios with different initial oxygen levels, in order to develop methods to reduce the toxic off-gas emissions and accumulation in storage spaces. Metal containers (45 l, 305 mm diameter by 610 mm long) were used to study the effect of headspace and oxygen levels on the off-gas emissions from wood pellets. Concentrations of CO(2), CO, and CH(4) in the headspace were measured using a gas chromatograph as a function of storage time. The results showed that the ratio of the headspace ratios and initial oxygen levels in the storage space significantly affected the off-gas emissions from wood pellets stored in a sealed container. Higher peak emission factors and higher emission rates are associated with higher headspace ratios. Lower emissions of CO(2) and CO were generated at room temperature under lower oxygen levels, whereas CH(4) emission is insensitive to the oxygen level. Replacing oxygen with inert gases in the storage space is thus a potentially effective method to reduce the biomass degradation and toxic off-gas emissions. The proper ventilation of the storage space can also be used to maintain a high oxygen level and low concentrations of toxic off-gassing compounds in the storage space, which is especially useful during the loading and unloading operations to control the hazards associated with the storage and transportation of wood pellets.

  18. Nutritional and Environmental Effects on Ammonia Emissions from Dairy Cattle Housing: A Meta-Analysis.

    PubMed

    Bougouin, Adeline; Leytem, April; Dijkstra, Jan; Dungan, Robert S; Kebreab, Ermias

    2016-07-01

    Nitrogen excreted in dairy manure can be potentially transformed and emitted as NH, which can create livestock and human respiratory problems and be an indirect source of NO. The objectives of this study were to: (i) investigate environmental factors influencing NH emissions from dairy housing; and (ii) identify key explanatory variables in the NH emissions prediction from dairy housing using a meta-analytical approach. Data from 25 studies were used for the preliminary analysis, and data from 10 studies reporting 87 treatment means were used for the meta-analysis. Season and flooring type significantly affected NH emissions. For nutritional effect analysis, the between-study variability (heterogeneity) of mean NH emission was estimated using random-effect models and had a significant effect ( < 0.01). Therefore, random-effect models were extended to mixed-effect models to explain heterogeneity regarding the available dietary and animal variables. The final mixed-effect model included milk yield, dietary crude protein, and dry matter intake separately, explaining 45.5% of NH emissions heterogeneity. A unit increase in milk yield (kg d) resulted in a 4.9 g cow d reduction in NH emissions, and a unit increase in dietary crude protein content (%) and dry matter intake (kg d) resulted in 10.2 and 16.3 g cow d increases in NH emissions, respectively, in the scope of this study. These results can be further used to help identify mitigation strategies to reduce NH emissions from dairy housing by developing predictive models that could determine variables with strong association with NH emissions.

  19. Effects of Aftermarket Control Technologies on Gas and Particle Phase Oxidative Potential from Diesel Engine Emissions

    EPA Science Inventory

    Particulate matter (PM) originating from diesel combustion is a public health concern due to its association with adverse effects on respiratory and cardiovascular diseases and lung cancer. This study investigated emissions from three stationary diesel engines (gensets) with var...

  20. [Effects of fungicide chlorothalonil on soil nitrous oxide and carbon dioxide emissions].

    PubMed

    Lang, Man; Cai, Zu-cong

    2008-12-01

    A 14 d incubation test at 60% WHC and 25 degrees C was conducted to study the effects of fungicide chlorothalonil at its application rates of 0, 5.5 mg x kg(-1) (field application rate, FR), 110 mg x kg(-1) (20FR) and 220 mg x kg(-1) (40FR) on the nitrous oxide (N2O) and carbon dioxide (CO2) emissions from acidic, neutral, and alkaline soils. The results indicated that the effects of chlorothalonil on the two gases emissions depended on its application rate and soil type. Comparing with no chlorothalonil application, the chlorothalonil at 20FR and 40FR inhibited the N2O emission from acid soil significantly, while that at FR, 20FR and 40FR stimulated the N2O emission from neutral soil, with the strongest effect at FR. Higher application rates (20FR and 40FR) of chlorothalonil inhibited the N2O emission from alkaline soil at the early stage of incubation, but stimulated it at late incubation stage. Chlorothalonil at FR had no obvious effects on the CO2 emission from test soils, but that at 20FR and 40FR promoted the CO2 emission from acid soil while inhibited it from neutral and alkaline soils significantly.

  1. [Effects of temperature on CH4 emission from subtropical common tree species leaves].

    PubMed

    Yang, Yan-Hua; Yi, Li-Ming; Xie, Jin-Sheng; Yang, Zhi-Jie; Jiang, Jun; Xu, Chao; Yang, Yu-Sheng

    2013-06-01

    Laboratory incubation test was conducted to study the effects of temperature on the CH4 emission from the leaves of subtropical common tree species Castanopsis carlesii, Schima superb, Cinnamomum chekiangense, Castsanopsis fabri, Cunninghamia lanceolata, and Citrus reticulata. Among the six tree species, only S. superb, C. reticulate, and C. fabri emitted CH4 at 10 degrees C. At above 20 degrees C, all the six species emitted CH4, and the average CH4 emission rate at above 30 degrees C (1.010 ng CH4 x g(-1) DM x h(-1)) was 2.96 times higher than that at 10-30 degrees C (0.255 ng CH4 x g(-1) DM x h(-1)). Moreover, increasing temperature had much more effects on the CH4 emission rate of C. reticulata and C. lanceolata than on that of the other four tree species. Incubation time affected the CH4 emission rate of all test tree species significantly, suggesting that the effects of temperature stress on the CH4 emission could be controlled by plant activity. Dry leaves could not emit CH4 no matter the temperature was very high or low. It was suggested that high temperature stress had important effects on the CH4 emission from subtropical tree leaves, and global warming could increase the CH4 emission from plants.

  2. Quantifying the effects of China's pollution control on atmospheric mercury emissions

    NASA Astrophysics Data System (ADS)

    Zhong, H.

    2014-12-01

    China has conducted series of air pollution control policies to reduce the pollutant emissions. Although not specifically for mercury (Hg), those policies are believed to have co-benefits on atmospheric Hg emission control. On the basis of field-tests data and updated information of energy conservation and emission control, we have developed multiple-year inventories of anthropogenic mercury emissions in China from 2005 to 2012. Three scenarios (scenario 0(S0), scenario 1(S1), scenario 2(S2)) with different emission controls and energy path are designed for prediction of the future Hg emissions for the country. In particular, comprehensive assessments has been conducted to evaluate the evolution of emission factors, recent emission trends, effects of control measures as well as the reliability of our results. The national total emissions of anthropogenic Hg are estimated to increase from 679.0 metric tons (t) in 2005 to 749.8 t in 2012, with the peak at 770.6 t in 2011. The annual growth rate of emissions can then be calculated at 2.1% during 2005-2011, much lower than that of energy consumption or economy of the country. Coal combustion, gold metallurgy and nonferrous metal smelting are the most significant Hg sources of anthropogenic origin, accounting together for 85% of national total emissions. Tightened air pollution controls in China should be important reasons for the smooth emission trends. Compared with 2005, 299 t Hg were reduced in 2010 from power plants, iron and steel smelting, nonferrous-smelting and cement production, benefiting from the improvement of control measures for those sectors. The speciation of Hg emissions is relatively stable for recent years, with the mass fractions of around 55%, 9% and 6% for Hg0, Hg2+ and Hgp respectively. Integrating the policy commitments on energy saving, different from the most conservative case S0, S2 shares the same energy path with S1, but includes more stringent emission control. Under those scenarios, we

  3. Emissions of ammonia, nitrous oxide and methane from cattle manure heaps: effect of compaction and covering

    NASA Astrophysics Data System (ADS)

    Chadwick, D. R.

    The effect of compaction and covering during storage of beef cattle ( Bos taurus) farmyard manure (FYM) on ammonia (NH 3), nitrous oxide (N 2O) and methane (CH 4) emissions was determined. Gaseous emission measurements were made over three separate storage periods of between 90 and 109 days. The effect of the different storage treatments on manure chemical composition was also determined. Compaction was carried out as the manure was put into store and the compacted manures covered with plastic sheeting. Compaction and covering significantly reduced NH 3 emissions from manure by over 90% during the first summer storage period (P<0.05). Over the subsequent storage periods NH 3 emissions from the FYM were small and unaffected by storage treatment. However, during the second storage period heavy and persistent rainfall during heap establishment and the following week appeared to reduce NH 3 emissions markedly. The low ammonium-N content of the FYM in the third storage period may have reduced the risk of NH 3 emission and reduced the relative effect of the compaction/covering treatment. Compaction and covering also significantly reduced N 2O emissions from cattle FYM (P<0.05) by ca. 30% during the first storage period. Subsequent N 2O emissions were unaffected by treatment. Methane emissions from cattle FYM were unaffected by treatment over the first storage period and were decreased by compaction in the second storage period yet was increased by compaction during the third storage period. It would appear that compacting and covering manure heaps does have the potential to reduce emissions of both NH 3 and N 2O when the manure contains relatively high ammonium-N contents. Additional benefits are that N and K are retained in the manure heap for agronomic benefit.

  4. EU effect: Exporting emission standards for vehicles through the global market economy.

    PubMed

    Crippa, M; Janssens-Maenhout, G; Guizzardi, D; Galmarini, S

    2016-12-01

    Emission data from EDGAR (Emissions Database for Global Atmospheric Research), rather than economic data, are used to estimate the effect of policies and of the global exports of policy-regulated goods, such as vehicles, on global emissions. The results clearly show that the adoption of emission standards for the road transport sector in the two main global markets (Europe and North America) has led to the global proliferation of emission-regulated vehicles through exports, regardless the domestic regulation in the country of destination. It is in fact more economically convenient for vehicle manufacturers to produce and sell a standard product to the widest possible market and in the greatest possible amounts. The EU effect (European Union effect) is introduced as a global counterpart to the California effect. The former is a direct consequence of the penetration of the EURO standards in the global markets by European and Japanese manufacturers, which effectively export the standard worldwide. We analyze the effect on PM2.5 emissions by comparing a scenario of non-EURO standards against the current estimates provided by EDGAR. We find that PM2.5 emissions were reduced by more than 60% since the 1990s worldwide. Similar investigations on other pollutants confirm the hypothesis that the combined effect of technological regulations and their diffusion through global markets can also produce a positive effect on the global environment. While we acknowledge the positive feedback, we also demonstrate that current efforts and standards will be totally insufficient should the passenger car fleets in emerging markets reach Western per capita figures. If emerging countries reach the per capita vehicle number of the USA and Europe under current technological conditions, then the world will suffer pre-1990 emission levels.

  5. Effects of future anthropogenic pollution emissions on global air quality

    NASA Astrophysics Data System (ADS)

    Pozzer, A.; Zimmermann, P.; Doering, U.; van Aardenne, J.; Dentener, F.; Lelieveld, J.

    2012-04-01

    The atmospheric chemistry general circulation model EMAC is used to estimate the impact of anthropogenic emission changes on global and regional air quality in recent and future years (2005, 2010, 2025 and 2050). The emission scenario assumes that population and economic growth largely determine energy consumption and consequent pollution sources ("business as usual"). By comparing with recent observations, it is shown that the model reproduces the main features of regional air pollution distributions though with some imprecision inherent to the coarse horizontal resolution (around 100 km). To identify possible future hot spots of poor air quality, a multi pollutant index (MPI) has been applied. It appears that East and South Asia and the Arabian Gulf regions represent such hotspots due to very high pollutant concentrations. In East Asia a range of pollutant gases and particulate matter (PM2.5) are projected to reach very high levels from 2005 onward, while in South Asia air pollution, including ozone, will grow rapidly towards the middle of the century. Around the Arabian Gulf, where natural PM2.5 concentrations are already high (desert dust), ozone levels will increase strongly. By extending the MPI definition, we calculated a Per Capita MPI (PCMPI) in which we combined population projections with those of pollution emissions. It thus appears that a rapidly increasing number of people worldwide will experience reduced air quality during the first half of the 21st century. It is projected that air quality for the global average citizen in 2050 will be comparable to the average in East Asia in the year 2005.

  6. Effects of sevoflurane and desflurane on otoacoustic emissions in humans.

    PubMed

    Gungor, Gurcan; Bozkurt-Sutas, Pervin; Gedik, Ozge; Atas, Ahmet; Babazade, Rovnat; Yilmaz, Mehmet

    2015-09-01

    Otoacoustic emissions (OAEs) are non-invasive, easy to apply and objective test methods which are widely used to determine the presence of hearing in audiology clinics. Under certain circumstances, the study should be applied under general anesthesia. The aim of this study was to determine the influence of new short-acting inhalation agents, desflurane and sevoflurane, on OAE in humans. These short-acting agents are widely used in general anesthesia. Thirty-one healthy patients who underwent septoplasty and turbinoplasty surgery were included in this study. Unpremedicated patients were anesthetized and monitored by a standard protocol except the inhalation agents. Desflurane and sevoflurane were added to the inhaled gas mixture at ~1MAC, 5-6 % and 1.5-2 %, respectively. Transient evoked otoacoustic emissions and distortion product otoacoustic emissions measured in both ears of each patient preoperatively in the operating room before induction, 5 min after induction, after the completion of surgical procedure while the anesthetic agents are still given and 1 h after surgery in the ward. Between-group and within-group comparisons and correlations with hemodynamic parameters were performed for statistical analysis. The measurements of 26 ears in desflurane group and 28 ears in sevoflurane group were evaluated. There were no differences in initial measurements between groups (p > 0.05). Both groups presented significant decrease in intraoperative measurements and changes in time were statistically significant (p < 0.05). The changes in OAEs were similar to changes in systemic blood pressures. Correlation between OAEs and systemic blood pressures were significant (p < 0.05). In conclusion, sevoflurane and desflurane decreased OAEs around 2-3 dB; OAEs are still measurable under inhalation agents. This provides some findings about the OAE status of patient, but the evaluations should be done with the impact of anesthetic agents in mind.

  7. Mobile source emission control cost-effectiveness: Issues, uncertainties, and results

    SciTech Connect

    Wang, M.Q.

    1994-12-01

    Emissions from mobile sources undoubtedly contribute to US urban air pollution problems. Consequently, mobile source control measures, ranging from vehicle emission standards to reducing vehicle travel, have been adopted or proposed to help attain air quality standards. To rank various mobile source control measures, various government agencies and private organizations calculate cost-effectiveness in dollars per ton of emissions reduced. Arguments for or against certain control measures are often made on the basis of the calculated cost-effectiveness. Yet, different studies may yield significantly different cost-effectiveness results, because of the various methodologies used and assumptions regarding the values of costs and emission reductions. Because of the methodological differences, the cost-effectiveness results may not be comparable between studies. Use of incomparable cost-effectiveness results may result in adoption of ineffective control measures. This paper first discusses some important methodological issues involved in cost-effectiveness calculation for mobile sources and proposes appropriate, systematic methods for dealing with these issues. Various studies have been completed recently to evaluate the cost-effectiveness of mobile source emission control measures. These studies resulted in wide variations in the cost-effectiveness for same control measures. Methodological assumptions used in each study are presented and, based on the proposed methods for cost-effectiveness calculation, adjustments are applied to the original estimates in each study to correct inappropriate methodological assumptions and to make the studies comparable. Finally, mobile source control measures are ranked on the basis of the adjusted cost-effectiveness estimates.

  8. Beaver-mediated methane emission: The effects of population growth in Eurasia and the Americas.

    PubMed

    Whitfield, Colin J; Baulch, Helen M; Chun, Kwok P; Westbrook, Cherie J

    2015-02-01

    Globally, greenhouse gas budgets are dominated by natural sources, and aquatic ecosystems are a prominent source of methane (CH(4)) to the atmosphere. Beaver (Castor canadensis and Castor fiber) populations have experienced human-driven change, and CH(4) emissions associated with their habitat remain uncertain. This study reports the effect of near extinction and recovery of beavers globally on aquatic CH4 emissions and habitat. Resurgence of native beaver populations and their introduction in other regions accounts for emission of 0.18-0.80 Tg CH(4) year(-1) (year 2000). This flux is approximately 200 times larger than emissions from the same systems (ponds and flowing waters that became ponds) circa 1900. Beaver population recovery was estimated to have led to the creation of 9500-42 000 km(2) of ponded water, and increased riparian interface length of >200 000 km. Continued range expansion and population growth in South America and Europe could further increase CH(4) emissions.

  9. Effects of Mid-Level Ethanol Blends on Conventional Vehicle Emissions

    SciTech Connect

    Knoll, K.; West, B.; Huff, S.; Thomas, J.; Orban, J.; Cooper, C.

    2010-06-01

    Tests were conducted in 2008 on 16 late-model conventional vehicles (1999-2007) to determine short-term effects of mid-level ethanol blends on performance and emissions. Vehicle odometer readings ranged from 10,000 to 100,000 miles, and all vehicles conformed to federal emissions requirements for their federal certification level. The LA92 drive cycle, also known as the Unified Cycle, was used for testing because it more accurately represents real-world acceleration rates and speeds than the Federal Test Procedure. Test fuels were splash-blends of up to 20 volume percent ethanol with federal certification gasoline. Both regulated and unregulated air-toxic emissions were measured. For the 16-vehicle fleet, increasing ethanol content resulted in reductions in average composite emissions of both nonmethane hydrocarbons and carbon monoxide and increases in average emissions of ethanol and aldehydes.

  10. Effects of ZnO Quantum Dots Decoration on the Field Emission Behavior of Graphene.

    PubMed

    Sun, Lei; Zhou, Xiongtu; Lin, Zhixian; Guo, Tailiang; Zhang, Yongai; Zeng, Yongzhi

    2016-11-23

    ZnO quantum dots (QDs) have been decorated on graphene deposited on patterned Ag electrodes as a field emission cathode by a solution process. Effects of ZnO QDs on the field emission behavior of graphene are studied by experiment and first-principles calculations. The results indicate that the attachment of ZnO QDs with a C atom leads to the enhancement of electron emission from graphene, which is mainly attributed to the reduction of the work function and ionization potential, and the increase of the Fermi level of graphene after the decoration. A change in the local density distribution and the density of states near the Fermi level may also account for this behavior. Our study may help to develop new field emission composites and expand ZnO QDs in applications for electron emission devices as well.

  11. Cost-effective means of reducing ammonia emissions from UK agriculture using the NARSES model

    NASA Astrophysics Data System (ADS)

    Webb, J.; Ryan, M.; Anthony, S. G.; Brewer, A.; Laws, J.; Aller, M. F.; Misselbrook, T. H.

    To comply with International agreements to improve air quality, signatory states need to reduce emissions of ammonia (NH 3). Since the majority of NH 3 emissions come from agriculture, measures may need to be implemented by the farming industry. Member states of the EU will, by 2010, require large pig and poultry production units to reduce NH 3 emissions to comply with the integrated pollution prevention and control directive (IPPC). The NARSES model uses a mass-flow method to estimate NH 3 emission from UK agriculture and to identify the most cost-effective means of reducing NH 3 emissions. Model runs were carried out to assess the likely impact of the IPPC Directive on UK NH 3 emissions and the sensitivity of model output to input data on the costs and abatement efficiencies of proposed abatement measures. The impact of the IPPC Directive is likely to be small, offering a reduction of c. 8700 t, 3.5% of total UK agricultural NH 3 emissions. Even large (30%) changes in our estimates of cost or changes of 10% in our estimates of abatement efficiency will make little difference to the ranking of abatement techniques according to cost-effectiveness. The most cost-effective reductions may be achieved by replacing urea fertilizer with ammonium nitrate, immediate incorporation of manures and slurries to tillage land by discs, storing all FYM and poultry manures before spreading to land and applying slurries to grassland by trailing shoe.

  12. Effects of 17β-estradiol on emissions of greenhouse gases in simulative natural water body.

    PubMed

    Ruan, Aidong; Zhao, Ying; Liu, Chenxiao; Zong, Fengjiao; Yu, Zhongbo

    2015-05-01

    Environmental estrogens are widely spread across the world and are increasingly thought of as serious contaminators. The present study looks at the influence of different concentrations of 17β-estradiol on greenhouse gas emissions (CO2 , CH4 , and N2 O) in simulated systems to explore the relationship between environmental estrogen-pollution and greenhouse gas emissions in natural water bodies. The present study finds that 17β-estradiol pollution in simulated systems has significant promoting effects on the emissions of CH4 and CO2 , although no significant effects on N2 O emissions. The present study indicates that 17β-estradiol has different effects on the different elements cycles; the mechanism of microbial ecology is under review.

  13. Finite field of view effects on inversion of limb thermal emission observations. [balloon sounding of stratosphere

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Guo, J.; Conrath, B. J.; Kunde, V. G.; Maguire, W. C.

    1985-01-01

    It is pointed out that the technique of thermal emission spectroscopy provides an effective means for remote sounding of stratospheric temperature structure and constituent distributions. One procedure for measuring the stratospheric infrared spectrum involves the conduction of observations along ray paths tangent to the stratospheric limb. Thermal emission limb tangent observations have certain advantages compared to other types of observations. The techniques for determining temperature and trace gas distributions from limb thermal emission radiances are based on the assumption that the bulk of opacity lies near the tangent point. Ideally, the field of view (FOV) of the observing instrument should be very small. The effect of a finite FOV is to reduce the spatial resolution of the retrieved temperature and constituent profiles. The present investigation is concerned with the effects of the FOV on the inversion of infrared thermal emission measurements for balloon platforms. Attention is given to a convenient method for determining the weighting functions.

  14. Nuclear effects on neutrino emissivities from nucleon-nucleon bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Stoica, S.; Paun, V. P.; Negoita, A. G.

    2004-06-01

    The rates of neutrino pair emission by nucleon-nucleon (NN) bremsstrahlung are calculated with the inclusion of the full contribution from a nuclear one pion exchange potential (OPEP). We compute the contributions from the neutron-neutron (nn), proton-proton (pp), and neutron-proton (np) processes for physical conditions encountered in supernovae and neutron stars, both in the degenerate (D) and nondegenerate (ND) limits. We find a significant reduction of these rates, especially for the nn and pp processes, in comparison with the case when the whole nuclear contribution was replaced by constants, representing the high-momentum limits of the expressions of the nuclear potential. Furthermore, we also perform the calculations by including contributions due to the ρ meson exchange between nucleons, in the OPEP. This may be relevant for processes produced in the inner core of neutron stars, where the density may exceed several times the standard nuclear density, and the short-range part of the NN interaction should be taken into account. These corrections lead to an additional suppression of the neutrino emission rates between (8 and 36)%, depending on the process [nn (pp) or np] and physical conditions (temperature and degeneracy of the nucleons).

  15. Effectiveness of Diesel Oxidation Catalyst in Reducing HC and CO Emissions from Reactivity Controlled Compression Ignition

    SciTech Connect

    Prikhodko, Vitaly Y; Curran, Scott; Parks, II, James E; Wagner, Robert M

    2013-01-01

    Reactivity Controlled Compression Ignition (RCCI) has been shown to allow for diesel-like or better brake thermal efficiency with significant reductions in nitrogen oxide (NOX) particulate matter (PM) emissions. Hydrocarbon (HC) and carbon monoxide (CO) emission levels, on the other hand, are similar to those of port fuel injected gasoline engines. The higher HC and CO emissions combined with the lower exhaust temperatures with RCCI operation present a challenge for current exhaust aftertreatments. The reduction of HC and CO emissions in a lean environment is typically achieved with an oxidation catalyst. In this work, several diesel oxidation catalysts (DOC) with different precious metal loadings were evaluated for effectiveness to control HC and CO emissions from RCCI combustion in a light-duty multi-cylinder engine operating on gasoline and diesel fuels. Each catalyst was evaluated in a steady-state engine operation with temperatures ranging from 160 to 260 C. A shift to a higher light-off temperature was observed during the RCCI operation. In addition to the steady-state experiments, the performances of the DOCs were evaluated during multi-mode engine operation by switching from diesel-like combustion at higher exhaust temperature and low HC/CO emissions to RCCI combustion at lower temperature and higher HC/CO emissions. High CO and HC emissions from RCCI generated an exotherm keeping the catalyst above the light-off temperature.

  16. Investigating the effect of electron emission pattern on RF gun beam quality

    NASA Astrophysics Data System (ADS)

    Rajabi, A.; Shokri, B.

    2016-05-01

    Thermionic radio frequency gun is one of the most promising choices to gain a high quality electron beam, used in the infrared free electron lasers and synchrotron radiation injectors. To study the quality of the beam in a compact electron source, the emission pattern effect on the beam dynamics should be investigated. In the presented work, we developed a 3D simulation code to model the real process of thermionic emission and to investigate the effect of emission pattern, by considering geometrical constraints, on the beam dynamics. According to the results, the electron bunch emittance varies considerably with the emission pattern. Simulation results have been validated via comparison with the well-known simulation codes such as ASTRA simulation code and CST microwave studio, as well as other simulation results in the literature. It was also demonstrated that by using a continuous wave laser beam for heating the cathode, the emission pattern full width at half maximum (FWHM) of the transverse emission distribution is proportional to FWHM of the Gaussian profile for the laser beam. Additionally, by using the developed code, the effect of wall structure around the cathode on the back bombardment effect has been studied. According to the results, for a stable operation of the RF gun, one should consider the nose cone in vicinity of the cathode surface to reduce the back-bombardment effect.

  17. Radiative effects of interannually varying vs. interannually invariant aerosol emissions from fires

    NASA Astrophysics Data System (ADS)

    Grandey, Benjamin S.; Lee, Hsiang-He; Wang, Chien

    2016-11-01

    Open-burning fires play an important role in the earth's climate system. In addition to contributing a substantial fraction of global emissions of carbon dioxide, they are a major source of atmospheric aerosols containing organic carbon, black carbon, and sulfate. These "fire aerosols" can influence the climate via direct and indirect radiative effects. In this study, we investigate these radiative effects and the hydrological fast response using the Community Atmosphere Model version 5 (CAM5). Emissions of fire aerosols exert a global mean net radiative effect of -1.0 W m-2, dominated by the cloud shortwave response to organic carbon aerosol. The net radiative effect is particularly strong over boreal regions. Conventionally, many climate modelling studies have used an interannually invariant monthly climatology of emissions of fire aerosols. However, by comparing simulations using interannually varying emissions vs. interannually invariant emissions, we find that ignoring the interannual variability of the emissions can lead to systematic overestimation of the strength of the net radiative effect of the fire aerosols. Globally, the overestimation is +23 % (-0.2 W m-2). Regionally, the overestimation can be substantially larger. For example, over Australia and New Zealand the overestimation is +58 % (-1.2 W m-2), while over Boreal Asia the overestimation is +43 % (-1.9 W m-2). The systematic overestimation of the net radiative effect of the fire aerosols is likely due to the non-linear influence of aerosols on clouds. However, ignoring interannual variability in the emissions does not appear to significantly impact the hydrological fast response. In order to improve understanding of the climate system, we need to take into account the interannual variability of aerosol emissions.

  18. Radiative effects of interannually varying vs. interannually invariant aerosol emissions from fires

    DOE PAGES

    Grandey, Benjamin S.; Lee, Hsiang-He; Wang, Chien

    2016-11-23

    Open-burning fires play an important role in the earth's climate system. In addition to contributing a substantial fraction of global emissions of carbon dioxide, they are a major source of atmospheric aerosols containing organic carbon, black carbon, and sulfate. These “fire aerosols” can influence the climate via direct and indirect radiative effects. In this study, we investigate these radiative effects and the hydrological fast response using the Community Atmosphere Model version 5 (CAM5). Emissions of fire aerosols exert a global mean net radiative effect of −1.0 W m−2, dominated by the cloud shortwave response to organic carbon aerosol. The net radiative effect ismore » particularly strong over boreal regions. Conventionally, many climate modelling studies have used an interannually invariant monthly climatology of emissions of fire aerosols. However, by comparing simulations using interannually varying emissions vs. interannually invariant emissions, we find that ignoring the interannual variability of the emissions can lead to systematic overestimation of the strength of the net radiative effect of the fire aerosols. Globally, the overestimation is +23 % (−0.2 W m−2). Regionally, the overestimation can be substantially larger. For example, over Australia and New Zealand the overestimation is +58 % (−1.2 W m−2), while over Boreal Asia the overestimation is +43 % (−1.9 W m−2). The systematic overestimation of the net radiative effect of the fire aerosols is likely due to the non-linear influence of aerosols on clouds. However, ignoring interannual variability in the emissions does not appear to significantly impact the hydrological fast response. In order to improve understanding of the climate system, we need to take into account the interannual variability of aerosol emissions.« less

  19. Time Resolved Measurements of Speciated Tailpipe Emissions from Motor Vehicles: Trends with Emission Control Technology, Cold Start Effects, and Speciation.

    PubMed

    Drozd, Greg T; Zhao, Yunliang; Saliba, Georges; Frodin, Bruce; Maddox, Christine; Weber, Robert J; Chang, M-C Oliver; Maldonado, Hector; Sardar, Satya; Robinson, Allen L; Goldstein, Allen H

    2016-12-20

    Experiments were conducted at the California Air Resources Board Haagen-Smit Laboratory to understand changes in vehicle emissions in response to stricter emissions standards over the past 25 years. Measurements included a wide range of volatile organic compounds (VOCs) for a wide range of spark ignition gasoline vehicles meeting varying levels of emissions standards, including all certifications from Tier 0 up to Partial Zero Emission Vehicle. Standard gas chromatography (GC) and high performance liquid chromatography (HLPC) analyses were employed for drive-cycle phase emissions. A proton-transfer-reaction mass spectrometer measured time-resolved emissions for a wide range of VOCs. Cold-start emissions occur almost entirely in the first 30-60 s for newer vehicles. Cold-start emissions have compositions that are not significantly different across all vehicles tested and are markedly different from neat fuel. Hot-stabilized emissions have varying importance depending on species and may require a driving distance of 200 miles to equal the emissions from a single cold start. Average commute distances in the U.S. suggest the majority of in-use vehicles have emissions dominated by cold starts. The distribution of vehicle ages in the U.S. suggests that within several years only a few percent of vehicles will have significant driving emissions compared to cold-start emissions.

  20. Climate effects of a hypothetical regional nuclear war: Sensitivity to emission duration and particle composition

    NASA Astrophysics Data System (ADS)

    Pausata, Francesco S. R.; Lindvall, Jenny; Ekman, Annica M. L.; Svensson, Gunilla

    2016-11-01

    Here, we use a coupled atmospheric-ocean-aerosol model to investigate the plume development and climate effects of the smoke generated by fires following a regional nuclear war between emerging third-world nuclear powers. We simulate a standard scenario where 5 Tg of black carbon (BC) is emitted over 1 day in the upper troposphere-lower stratosphere. However, it is likely that the emissions from the fires ignited by bomb detonations include a substantial amount of particulate organic matter (POM) and that they last more than 1 day. We therefore test the sensitivity of the aerosol plume and climate system to the BC/POM ratio (1:3, 1:9) and to the emission length (1 day, 1 week, 1 month). We find that in general, an emission length of 1 month substantially reduces the cooling compared to the 1-day case, whereas taking into account POM emissions notably increases the cooling and the reduction of precipitation associated with the nuclear war during the first year following the detonation. Accounting for POM emissions increases the particle size in the short-emission-length scenarios (1 day/1 week), reducing the residence time of the injected particle. While the initial cooling is more intense when including POM emission, the long-lasting effects, while still large, may be less extreme compared to the BC-only case. Our study highlights that the emission altitude reached by the plume is sensitive to both the particle type emitted by the fires and the emission duration. Consequently, the climate effects of a nuclear war are strongly dependent on these parameters.

  1. Effect of biochar and liming on soil nitrous oxide emissions from a temperate maize cropping system

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    Biochar, a carbon-rich, porous pyrolysis product of organic residues may positively affect plant yield and can, owing to its inherent stability, promote soil carbon sequestration when amended to agricultural soils. Another possible effect of biochar is the reduction in emissions of nitrous oxide (N2O). A number of laboratory incubations have shown significantly reduced N2O emissions from soil when mixed with biochar. Emission measurements under field conditions however are more scarce and show weaker or no reductions, or even increases in N2O emissions. One of the hypothesised mechanisms for reduced N2O emissions from soil is owing to the increase in soil pH following the application of alkaline biochar. To test the effect of biochar on N2O emissions in a temperate maize cropping system, we set up a field trial with a 20t ha-1 biochar treatment, a limestone treatment adjusted to the same pH as the biochar treatment (pH 6.5), and a control treatment without any addition (pH 6.1). An automated static chamber system measured N2O emissions for each replicate plot (n = 3) every 3.6 h over the course of 8 months. The field was conventionally fertilised at a rate of 160 kg N ha-1 in three applications of 40, 80 and 40 kg N ha-1 as ammonium nitrate. Cumulative N2O emissions were 52 % smaller in the biochar compared to the control treatment. However, the effect of the treatments overall was not statistically significant (p = 0.27) because of the large variability in the data set. Limed soils emitted similar mean cumulative amounts of N2O as the control. There is no evidence that reduced N2O emissions with biochar relative to the control is solely caused by a higher soil pH.

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

    PubMed

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

    2015-06-15

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

  3. Short run effects of a price on carbon dioxide emissions from U.S. electric generators.

    PubMed

    Newcomer, Adam; Blumsack, Seth A; Apt, Jay; Lave, Lester B; Morgan, M Granger

    2008-05-01

    The price of delivered electricity will rise if generators have to pay for carbon dioxide emissions through an implicit or explicit mechanism. There are two main effects that a substantial price on CO2 emissions would have in the short run (before the generation fleet changes significantly). First, consumers would react to increased price by buying less, described by their price elasticity of demand. Second, a price on CO2 emissions would change the order in which existing generators are economically dispatched, depending on their carbon dioxide emissions and marginal fuel prices. Both the price increase and dispatch changes depend on the mix of generation technologies and fuels in the region available for dispatch, although the consumer response to higher prices is the dominant effect. We estimate that the instantaneous imposition of a price of $35 per metric ton on CO2 emissions would lead to a 10% reduction in CO2 emissions in PJM and MISO at a price elasticity of -0.1. Reductions in ERCOT would be about one-third as large. Thus, a price on CO2 emissions that has been shown in earlier workto stimulate investment in new generation technology also provides significant CO2 reductions before new technology is deployed at large scale.

  4. Climate change alters leaf anatomy, but has no effects on volatile emissions from Arctic plants.

    PubMed

    Schollert, Michelle; Kivimäenpää, Minna; Valolahti, Hanna M; Rinnan, Riikka

    2015-10-01

    Biogenic volatile organic compound (BVOC) emissions are expected to change substantially because of the rapid advancement of climate change in the Arctic. BVOC emission changes can feed back both positively and negatively on climate warming. We investigated the effects of elevated temperature and shading on BVOC emissions from arctic plant species Empetrum hermaphroditum, Cassiope tetragona, Betula nana and Salix arctica. Measurements were performed in situ in long-term field experiments in subarctic and high Arctic using a dynamic enclosure system and collection of BVOCs into adsorbent cartridges analysed by gas chromatography-mass spectrometry. In order to assess whether the treatments had resulted in anatomical adaptations, we additionally examined leaf anatomy using light microscopy and scanning electron microscopy. Against expectations based on the known temperature and light-dependency of BVOC emissions, the emissions were barely affected by the treatments. In contrast, leaf anatomy of the studied plants was significantly altered in response to the treatments, and these responses appear to differ from species found at lower latitudes. We suggest that leaf anatomical acclimation may partially explain the lacking treatment effects on BVOC emissions at plant shoot-level. However, more studies are needed to unravel why BVOC emission responses in arctic plants differ from temperate species.

  5. The effectiveness of net negative carbon dioxide emissions in reversing anthropogenic climate change

    NASA Astrophysics Data System (ADS)

    Tokarska, Katarzyna B.; Zickfeld, Kirsten

    2015-09-01

    Artificial removal of CO2 from the atmosphere (also referred to as negative emissions) has been proposed as a means to restore the climate system to a desirable state, should the impacts of climate change become ‘dangerous’. Here we explore whether negative emissions are indeed effective in reversing climate change on human timescales, given the potentially counteracting effect of natural carbon sinks and the inertia of the climate system. We designed a range of CO2 emission scenarios, which follow a gradual transition to a zero-carbon energy system and entail implementation of various amounts of net-negative emissions at technologically plausible rates. These scenarios are used to force an Earth System Model of intermediate complexity. Results suggest that while it is possible to revert to a desired level of warming (e.g. 2 °C above pre-industrial) after different levels of overshoot, thermosteric sea level rise is not reversible for at least several centuries, even under assumption of large amounts of negative CO2 emissions. During the net-negative emission phase, artificial CO2 removal is opposed by CO2 outgassing from natural carbon sinks, with the efficiency of CO2 removal—here defined as the drop in atmospheric CO2 per unit negative emission—decreasing with the total amount of negative emissions.

  6. Effects of Fuel Ethanol Use on Fuel-Cycle Energy and Greenhouse Gas Emissions

    SciTech Connect

    C. Saricks; D. Santini; M. Wang

    1999-02-08

    We estimated the effects on per-vehicle-mile fuel-cycle petroleum use, greenhouse gas (GHG) emissions, and energy use of using ethanol blended with gasoline in a mid-size passenger car, compared with the effects of using gasoline in the same car. Our analysis includes petroleum use, energy use, and emissions associated with chemicals manufacturing, farming of corn and biomass, ethanol production, and ethanol combustion for ethanol; and petroleum use, energy use, and emissions associated with petroleum recovery, petroleum refining, and gasoline combustion for gasoline. For corn-based ethanol, the key factors in determining energy and emissions impacts include energy and chemical usage intensity of corn farming, energy intensity of the ethanol plant, and the method used to estimate energy and emissions credits for co-products of corn ethanol. The key factors in determining the impacts of cellulosic ethanol are energy and chemical usage intensity of biomass farming, ethanol yield per dry ton of biomass, and electricity credits in cellulosic ethanol plants. The results of our fuel-cycle analysis for fuel ethanol are listed below. Note that, in the first half of this summary, the reductions cited are per-vehicle-mile traveled using the specified ethanol/gasoline blend instead of conventional (not reformulated) gasoline. The second half of the summary presents estimated changes per gallon of ethanol used in ethanol blends. GHG emissions are global warming potential (GWP)-weighted, carbon dioxide (CO2)-equivalent emissions of CO2, methane (CH4), and nitrous oxide (N2O).

  7. MODELING THE EFFECT OF CHLORINE EMISSIONS ON ATMOSPHERIC OZONE AND SECONDARY ORGANIC AEROSOL CONCENTRATIONS ACROSS THE UNITED STATES

    EPA Science Inventory

    This paper presents the modeled effects of natural and anthropogenic chlorine emissions on the atmospheric concentrations of ozone and secondary organic aerosol across the United States. The model calculations include anthropogenic molecular chlorine emissions, anthropogenic hypo...

  8. Forte Fortissimo for amateur musicians: no effect on otoacoustic emissions.

    PubMed

    Møllerløkken, Ole J; Magerøy, Nils; Bråtveit, Magne; Lind, Ola; Moen, Bente E

    2013-03-01

    Many amateur musicians are likely to be exposed to high sound levels during rehearsals. Measuring otoacoustic emissions (OAE) is an objective technique to assess hearing ability and can be used as an early predictor of hearing loss. This study aimed to record sound levels at an amateur brass band rehearsal and to examine the cochlear function of the musicians by evaluating distortion product (DP) OAE amplitudes before and after sound exposure. Twenty-four brass band musicians and 10 office workers were examined with personal noise measurements and DPOAE tests before and after a music rehearsal or one office workday, respectively. The sound levels in the brass band ranged from 92 to 100 dBA, LaEQ 96 dBA. However, the amateur brass band members had no change in DPOAEs after this exposure compared to pre-exposure levels and compared to office workers.

  9. Effect of vitamin B12 deficiency on otoacoustic emissions.

    PubMed

    Karli, R; Gül, A; Uğur, B

    2013-08-01

    The aim of this study was to investigate the possible association between otoacoustic emission (OAE) values and cochlear function in patients with vitamin B12 deficiency and no evidence of symptomatic hearing loss. Two groups were studied: Group 1: patients with vitamin B12 deficiency; Group 2: a matched control group of patients with normal vitamin B12 levels. There was no evidence of symptomatic hearing loss in either group. Transiently evoked OAEs (TEOAEs) and spontaneous OAEs (SOAEs) were recorded. A comparative analysis of the studied parameters revealed that results at TEOAE 1000, SOAEs 1500 and SOAEs 4000 Hz were somewhat lower in the vitamin B12 deficient group compared with the control group. According to our findings, there was a significant association between vitamin B12 deficiency and cochlear dysfunction. We recommend that routine vitamin B12 serum levels be determined when evaluating patients for symptomatic hearing loss.

  10. Effect of some Turkish vegetable oil-diesel fuel blends on exhaust emissions

    SciTech Connect

    Ergeneman, M.; Oezaktas, T.; Cigizoglu, K.B.; Karaosmanoglu, F.; Arslan, E.

    1997-10-01

    For different types of vegetable oils of Turkish origin (sunflower, corn, soybean, and olive oil) were blended with grade No. 2-D diesel fuel at a ratio of 20/80 (v/v). The effect of the compression ratio on exhaust emissions is investigated in an American Society for Testing and Materials (ASTM)-cooperative fuel research (CFR) engine working with the mentioned fuel blends and a baseline diesel fuel. A decrease in soot, CO, CO{sub 2}, and HC emissions and an increase in NO{sub x} emissions have been observed for fuel blends compared to diesel fuel.

  11. Jupiter's decameter and kilometer emissions: Satellite effects and long term periodicities

    NASA Astrophysics Data System (ADS)

    St. Cyr, O. C.

    1985-12-01

    The results of observational studies of Jupiter's decameter (DAM) and kilometer (KOM) radio emissions are presented. The initial goal was to investigate the role of Jupiter's major satellites in modulating these sporadic emissions. The concepts of electromagnetic induction are reviewed in planet-sized bodies and then the Jovian magnetosphere environment and the physical characteristics of the Galilean satellites and Amalthea are described. Since the phase of Io is known to modulate the DAM emission, the problem of orbital resonance among the Galilean satellites is addressed. A secondary goal was to search for long term periodicities and other effects in the groundbased DAM data.

  12. Effects of the biodiesel blend fuel on aldehyde emissions from diesel engine exhaust

    NASA Astrophysics Data System (ADS)

    Peng, Chiung-Yu; Yang, Hsi-Hsien; Lan, Cheng-Hang; Chien, Shu-Mei

    Interest in use of biodiesel fuels derived from vegetable oils or animal fats as alternative fuels for petroleum-based diesels has increased due to biodiesels having similar properties of those of diesels, and characteristics of renewability, biodegradability and potential beneficial effects on exhaust emissions. Generally, exhaust emissions of regulated pollutants are widely studied and the results favor biodiesels on CO, HC and particulate emissions; however, limited and inconsistent data are showed for unregulated pollutants, such as carbonyl compounds, which are also important indicators for evaluating available vehicle fuels. For better understanding biodiesel, this study examines the effects of the biodiesel blend fuel on aldehyde chemical emissions from diesel engine exhausts in comparison with those from the diesel fuel. Test engines (Mitsubishi 4M40-2AT1) with four cylinders, a total displacement of 2.84 L, maximum horsepower of 80.9 kW at 3700 rpm, and maximum torque of 217.6 N m at 2000 rpm, were mounted and operated on a Schenck DyNAS 335 dynamometer. Exhaust emission tests were performed several times for each fuel under the US transient cycle protocol from mileages of 0-80,000 km with an interval of 20,000 km, and two additional measurements were carried out at 40,000 and 80,000 km after maintenance, respectively. Aldehyde samples were collected from diluted exhaust by using a constant volume sampling system. Samples were extracted and analyzed by the HPLC/UV system. Dominant aldehydes of both fuels' exhausts are formaldehyde and acetaldehyde. These compounds together account for over 75% of total aldehyde emissions. Total aldehyde emissions for B20 (20% waste cooking oil biodiesel and 80% diesel) and diesel fuels are in the ranges of 15.4-26.9 mg bhp-h -1 and 21.3-28.6 mg bhp-h -1, respectively. The effects of increasing mileages and maintenance practice on aldehyde emissions are insignificant for both fuels. B20 generates slightly less emission than

  13. Environmental effects of increased coal utilization: ecological effects of gaseous emissions from coal combustion.

    PubMed Central

    Glass, N R

    1979-01-01

    This report is limited to an evaluation of the ecological and environmental effects of gaseous emissions and aerosols of various types which result from coal combustion. It deals with NOx, SOx, fine particulate, photochemical oxidant and acid precipitation as these pollutants affect natural and managed resources and ecosystems. Also, synergistic effects involving two or more pollutants are evaluated as well as ecosystem level effects of gaseous pollutants. There is a brief summary of the effects on materials and atmospheric visibility of increased coal combustion. The economic implications of ecological effects are identified to the extent they can be determined within acceptable limits. Aquatic and terrestrial effects are distinguished where the pollutants in question are clearly problems in both media. At present, acid precipitation is most abundant in the north central and northeastern states. Total SOx and NOx emissions are projected to remain high in these regions while increasing relatively more in the western than in the eastern regions of the country. A variety of ecological processes are affected and altered by air pollution. Such processes include community succession and retrogression, nutrient biogeochemical cycling, photosynthetic activity, primary and secondary productivity, species diversity and community stability. Estimates of the non health-related cost of air pollutants range from several hundred million dollars to $1.7 billion dollars per year. In general, these estimates include only those relatively easily measured considerations such as the known losses to cultivate crops from acute air pollution episodes or the cost of frequent repainting required as a result of air pollution. No substantial nationwide estimates of losses to forest productivity, natural ecosystem productivity which is tapped by domestic grazing animals and wildlife, and other significant dollar losses are available. PMID:44247

  14. Effects of lignite application on ammonia and nitrous oxide emissions from cattle pens.

    PubMed

    Sun, Jianlei; Bai, Mei; Shen, Jianlin; Griffith, David W T; Denmead, Owen T; Hill, Julian; Lam, Shu Kee; Mosier, Arvin R; Chen, Deli

    2016-09-15

    Beef cattle feedlots are a major source of ammonia (NH3) emissions from livestock industries. We investigated the effects of lignite surface applications on NH3 and nitrous oxide (N2O) emissions from beef cattle feedlot pens. Two rates of lignite, 3 and 6kgm(-2), were tested in the treatment pen. No lignite was applied in the control pen. Twenty-four Black Angus steers were fed identical commercial rations in each pen. We measured NH3 and N2O concentrations continuously from 4th Sep to 13th Nov 2014 using Quantum Cascade Laser (QCL) NH3 analysers and a closed-path Fourier Transform Infrared Spectroscopy analyser (CP-FTIR) in conjunction with the integrated horizontal flux method to calculate NH3 and N2O fluxes. During the feeding period, 16 and 26% of the excreted nitrogen (N) (240gNhead(-1)day(-1)) was lost via NH3 volatilization from the control pen, while lignite application decreased NH3 volatilization to 12 and 18% of the excreted N, for Phase 1 and Phase 2, respectively. Compared to the control pen, lignite application decreased NH3 emissions by approximately 30%. Nitrous oxide emissions from the cattle pens were small, 0.10 and 0.14gN2O-Nhead(-1)day(-1) (<0.1% of excreted N) for the control pen, for Phase 1 and Phase 2, respectively. Lignite application increased direct N2O emissions by 40 and 57%, to 0.14 and 0.22gN2O-Nhead(-1)day(-1), for Phase 1 and Phase 2, respectively. The increase in N2O emissions resulting from lignite application was counteracted by the lower indirect N2O emission due to decreased NH3 volatilization. Using 1% as a default emission factor of deposited NH3 for indirect N2O emissions, the application of lignite decreased total N2O emissions.

  15. Experimental Measurements of the Effects of Photo-chemical Oxidation on Aerosol Emissions in Aircraft Exhaust

    NASA Astrophysics Data System (ADS)

    Miracolo, M. A.; Presto, A. A.; Hennigan, C. J.; Nguyen, N.; Ranjan, M.; Reeder, A.; Lipsky, E.; Donahue, N. M.; Robinson, A. L.

    2009-12-01

    Many military and commercial airfields are located in non-attainment areas for particulate matter (PM2.5), but the contribution of emissions from in-use aircraft to local and regional PM2.5 concentrations is uncertain. In collaboration with the Pennsylvania Air National Guard 171st Air Refueling Wing, the Carnegie Mellon University (CMU) Mobile Laboratory was deployed to measure fresh and aged emissions from a CFM56-2B1 gas-turbine engine mounted on a KC-135 Stratotanker airframe. The CFM-56 family of engine powers many different types of military and civilian aircraft, including the Boeing 737 and several Airbus models. It is one of the most widely deployed models of engines in the world. The goal of this work was to measure the gas-particle partitioning of the fresh emissions at atmospherically relevant conditions and to investigate the effect of atmospheric oxidation on aerosol loadings as the emissions age. Emissions were sampled from an inlet installed one meter downstream of the engine exit plane and transferred into a portable smog chamber via a heated inlet line. Separate experiments were conducted at different engine loads ranging from ground idle to take-off rated thrust. During each experiment, some diluted exhaust was added to the chamber and the volatility of the fresh emissions was then characterized using a thermodenuder. After this characterization, the chamber was exposed to either ambient sunlight or UV lights to initiate photochemical oxidation, which produced secondary aerosol and ozone. A suite of gas and particle-phase instrumentation was used to characterize the evolution of the gas and particle-phase emissions, including an aerosol mass spectrometer (AMS) to measure particle size and composition distributions. Fresh emissions of fine particles varied with engine load with peak emission factors at low and high loads. At high engine loads, the fresh emissions were dominated by black carbon; at low loads volatile organic carbon emissions were

  16. Nonlocal effects: relevance for the spontaneous emission rates of quantum emitters coupled to plasmonic structures.

    PubMed

    Filter, Robert; Bösel, Christoph; Toscano, Giuseppe; Lederer, Falk; Rockstuhl, Carsten

    2014-11-01

    The spontaneous emission rate of dipole emitters close to plasmonic dimers are theoretically studied within a nonlocal hydrodynamic model. A nonlocal model has to be used since quantum emitters in the immediate environment of a metallic nanoparticle probe its electronic structure. Compared to local calculations, the emission rate is significantly reduced. The influence is mostly pronounced if the emitter is located close to sharp edges. We suggest to use quantum emitters to test nonlocal effects in experimentally feasible configurations.

  17. [Analysis on effect of inspection and maintenance (I/M) program for vehicle emission reduction].

    PubMed

    Zhang, H; Fu, L; Hao, J; Zhou, Z; Wang, X

    2001-01-01

    An Inspection and maintenance(I/M) programme aims to ensure that motor vehicle emission control systems are functioning properly throughout the two stage idle test. Based on three factors including data from inspection, standard for inspection and failure rate, the effectiveness of the current I/M program was studied through the cumulative distributions. The disadvantages of the cutpoints, institution settings, management, and supervision was also analyzed. The fundamental law of emission limits was proposed.

  18. [Effect of Biochar on Soil Greenhouse Gas Emissions in Semi-arid Region].

    PubMed

    Guo, Yan-liang; Wang, Dan-dan; Zheng, Ji-yong; Zhao, Shi-wei; Zhang, Xing-chang

    2015-09-01

    This study aimed to investigate the effects of biochar addition on the emission of greenhouse gases from farmland soil in semi-arid region. Through an in-situ experiments, the influence of sawdust biochar(J) and locust tree skin biochar (H) at three doses (1%, 3%, and 5% of quality percentage) on C2, CH4 and N2O emissions were studied within the six months in the south of Ningxiaprovince. The results indicated that soil CO2 emission flux was slightly increased with the addition doses for both biochars, and the averaged CO2 emission flux for sawdust and locust tree skin biochar was enhanced by 1. 89% and 3. 34% compared to the control, but the difference between treatments was not statistically significant. The soil CH4 emission was decreased with the increasing of biochar doses, by 1. 17%, 2. 55%, 4. 32% for J1, J3, J5 and 2. 35%, 5. 83%, 7. 32% for H1, H3, H5, respectively. However, the difference was statistically significant only for J5, H3 and H5 treatments (P <0. 05). Across addition doses, there was no apparent effect on soil N2O emission. Our study indicated that the biochar has no significant influence on soil CO2 and N2O emissions within six months in semi-arid region and can significantly influence soil CH4 emissions (P < 0. 05). As for biochar type, the locust tree skin biochar is significantly better than the sawdust biochar in terms of restraining CH4 emission(P = 0. 048).

  19. Evaluation of light dependence of monoterpene emission and its effect on surface ozone concentration

    NASA Astrophysics Data System (ADS)

    Nishimura, Hiroshi; Shimadera, Hikari; Kondo, Akira; Bao, Hai; Shrestha, Kundan Lal; Inoue, Yoshio

    2015-03-01

    This study evaluated the effect of light intensity on monoterpene emission from the three dominant coniferous tree species in Japan (Cryptomeria japonica, Chamaecyparis obtusa and Pinus densiflora). Monoterpene emission experiments were conducted by using a growth chamber where temperature and light intensity can be controlled. In the experiments, air temperature was set at 30 °C and light intensity was set at 0, 500, 700, 850, 1200, and 1400 μmol m-2s-1. Because monoterpene emissions from the three tree species similarly increased with increasing light intensity, a new empirical equation considering light dependence was proposed to estimate monoterpene emission. In addition, monoterpene emission in the Kinki region of Japan was estimated with and without light dependence using meteorological field produced by the Weather Research and Forecasting model (WRF) in summer 2010. The monoterpene emissions estimated with light dependence were larger than those without light dependence in the daytime under clear sky conditions and consistently smaller in the nighttime. In order to evaluate the effect of light dependence of monoterpene emission on ozone concentration in the Kinki region, two cases of air quality simulations by the Community Multiscale Air Quality model (CMAQ) were conducted using the monoterpene emission data estimated with and without light dependence. Comparisons of the two cases showed that the monoterpene emission changes due to light dependence slightly but systematically affected ozone concentrations. Monoterpene generally played a role of reducing ozone concentration in the CMAQ simulations. Consequently, because of the light dependence, the mean daily maximum ozone concentrations decreased by 0.3 ppb on average with a maximum of 2.2 ppb, and the mean daily minimum values increased by 0.4 ppb on average with a maximum of 1.8 ppb in the Kinki region in summer 2010.

  20. Effects of Coaxial Air on Nitrogen-Diluted Hydrogen Jet Diffusion Flame Length and NOx Emission

    SciTech Connect

    Weiland, N.T.; Chen, R.-H.; Strakey, P.A.

    2007-10-01

    Turbulent nitrogen-diluted hydrogen jet diffusion flames with high velocity coaxial air flows are investigated for their NOx emission levels. This study is motivated by the DOE turbine program’s goal of achieving 2 ppm dry low NOx from turbine combustors running on nitrogen-diluted high-hydrogen fuels. In this study, effects of coaxial air velocity and momentum are varied while maintaining low overall equivalence ratios to eliminate the effects of recirculation of combustion products on flame lengths, flame temperatures, and resulting NOx emission levels. The nature of flame length and NOx emission scaling relationships are found to vary, depending on whether the combined fuel and coaxial air jet is fuel-rich or fuel-lean. In the absence of differential diffusion effects, flame lengths agree well with predicted trends, and NOx emissions levels are shown to decrease with increasing coaxial air velocity, as expected. Normalizing the NOx emission index with a flame residence time reveals some interesting trends, and indicates that a global flame strain based on the difference between the fuel and coaxial air velocities, as is traditionally used, is not a viable parameter for scaling the normalized NOx emissions of coaxial air jet diffusion flames.

  1. Effects of Changing Emissions on Ozone and Particulates in the Northeastern United States

    NASA Astrophysics Data System (ADS)

    Frost, G. J.; McKeen, S.; Trainer, M.; Ryerson, T.; Holloway, J.; Brock, C.; Middlebrook, A.; Wollny, A.; Matthew, B.; Williams, E.; Lerner, B.; Fortin, T.; Sueper, D.; Parrish, D.; Fehsenfeld, F.; Peckham, S.; Grell, G.; Peltier, R.; Weber, R.; Quinn, P.; Bates, T.

    2004-12-01

    Emissions of nitrogen oxides (NOx) from electric power generation have decreased in recent years due to changes in burner technology and fuels used. Mobile NOx emissions assessments are less certain, since they must account for increases in vehicle miles traveled, changes in the proportion of diesel and gasoline vehicles, and more stringent controls on engines and fuels. The impact of these complicated emission changes on a particular region's air quality must be diagnosed by a combination of observation and model simulation. The New England Air Quality Study - Intercontinental Transport and Chemical Transformation 2004 (NEAQS-ITCT 2004) program provides an opportunity to test the effects of changes in emissions of NOx and other precursors on air quality in the northeastern United States. An array of ground, marine, and airborne observation platforms deployed during the study offer checks on emission inventories and air quality model simulations, like those of the Weather Research and Forecasting model coupled with online chemistry (WRF-Chem). Retrospective WRF-Chem runs are carried out with two EPA inventories, one compiled for base year 1999 and an update for 2004 incorporating projected and known changes in emissions during the past 5 years. Differences in model predictions of ozone, particulates, and other tracers using the two inventories are investigated. The inventories themselves and the model simulations are compared with the extensive observations available during NEAQS-ITCT 2004. Preliminary insights regarding the sensitivity of the model to NOx emission changes are discussed.

  2. Effects of mixing and covering with mature compost on gaseous emissions during composting.

    PubMed

    Luo, Wen Hai; Yuan, Jing; Luo, Yi Ming; Li, Guo Xue; Nghiem, Long D; Price, William E

    2014-12-01

    This study investigated effects of mature compost on gaseous emissions during composting using pig manure amended with corn stalks. Apart from a control treatment, three treatments were conducted with the addition of 5% (wet weight of raw materials) of mature compost: (a) mixing raw materials with mature compost at the beginning of composting; (b) covering raw materials with mature compost throughout the experimental period; and (c) covering raw materials with mature compost at the start of composting, but incorporating it into composting pile on day 6 of composting. Mature compost used for the last treatment was inoculated with 2% (wet weight) of raw materials of strain M5 (a methanotrophic bacterium) solution. During 30-d of composting, three treatments with the addition of mature compost could reduce CH4 emission by 53-64% and N2O emission by 43-71%. However, covering with mature compost throughout the experimental period increased cumulative NH3 emission by 61%, although it could reduce 34% NH3 emission in the first 3d. Inoculating strain M5 in mature compost covered on the top of composting pile within first 6d enhanced CH4 oxidation, but simultaneously increased N2O emission. In addition, mixing with mature compost could improve compost maturity. Given the operational convenience in practice, covering with mature compost and then incorporating it into composting pile is a suitable approach to mitigate gaseous emissions during composting.

  3. 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.

  4. Effectiveness of US state policies in reducing CO2 emissions from power plants

    NASA Astrophysics Data System (ADS)

    Grant, Don; Bergstrand, Kelly; Running, Katrina

    2014-11-01

    President Obama's landmark initiative to reduce the CO2 emissions of existing power plants, the nation's largest source of greenhouse gas (GHG) pollutants, depends heavily on states and their ability to devise policies that meet the goals set by the Environmental Protection Agency (EPA). Under the EPA's proposed Clean Power Plan, states will be responsible for cutting power plants' carbon pollution 30% from 2005 levels by 2030. States have already adopted several policies to reduce the electricity sector's climate impact. Some of these policies focus on reducing power plants' CO2 emissions, and others address this outcome in a more roundabout fashion by encouraging energy efficiency and renewable energy. However, it remains unclear which, if any, of these direct and indirect strategies actually mitigate plants' emissions because scholars have yet to test their effects using plant-level emission data. Here we use a newly released data source to determine whether states' policies significantly shape individual power plants' CO2 emissions. Findings reveal that certain types of direct strategy (emission caps and GHG targets) and indirect ones (public benefit funds and electric decoupling) lower plants' emissions and thus are viable building blocks of a federal climate regime.

  5. Effects of ethanol-blended gasoline on air pollutant emissions from motorcycle.

    PubMed

    Yao, Yung-Chen; Tsai, Jiun-Horng; Chiang, Hung-Lung

    2009-09-15

    The effect of ethanol-gasoline blends on criteria air pollutant emissions was investigated in a four-stroke motorcycle. The ethanol was blended with unleaded gasoline in four percentages (3, 10, 15, and 20% v/v) and controlled at a constant research octane number, RON (95), to accurately represent commercial gasoline. CO, THC, and NOx emissions were evaluated using the Economic Commission for Europe cycle on the chassis dynamometers. The results of the ethanol-gasoline blends were compared to those of commercial unleaded gasoline with methyl tert-butyl ether as the oxygenated additive. In general, the exhaust CO and NOx emissions decreased with increasing oxygen content in fuels. In contrast, ethanol added in the gasoline did not reduce the THC emissions for a constant RON gasoline. The 15% ethanol blend had the highest emission reductions relative to the reference fuel. The high ethanol-gasoline blend ratio (20%) resulted in a less emission reduction than those of low ratio blends (<15%). This may be attributed to the changes in the combustion conditions in the carburetor engine with 20% ethanol addition. Furthermore, the influence of ethanol-gasoline blends on the reduction of exhaust emissions was observed at different driving modes, especially at 15km/h cruising speed for CO and THC and acceleration stages for NOx.

  6. 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

  7. 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

    2016-06-21

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

  8. [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.

  9. [Evaluation on the Effectiveness of Vehicle Exhaust Emission Control Measures During the APEC Conference in Beijing].

    PubMed

    Fan, Shou-bin; Tian, Ling-di; Zhang, Dong-xu; Guo, Jin-jin

    2016-01-15

    Vehicle emission is one of the primary factors affecting the quality of atmospheric environment in Beijing. In order to improve the air quality during APEC conference, strict control measures including vehicle emission control were taken in Beijing during APEC meeting. Based on the activity level data of traffic volume, vehicle speed and vehicle types, the inventory of motor vehicle emissions in Beijing was developed following bottom-up methodology to assess the effectiveness of the control measures. The results showed that the traffic volume of Beijing road network during the APEC meeting decreased significantly, the vehicle speed increased obviously, and the largest decline of traffic volume was car. CO, NOx, HC and PM emissions of vehicle exhaust were reduced by 15.1%, 22.4%, 18.4% and 21.8% for freeways, 29.9%, 36.4%, 32.7% and 35.8% for major arterial, 35.7%, 41.7%, 38.4% and 41.2% for minor arterial, 40.8%, 46.5%, 43.1% and 46.0% for collectors, respectively. The vehicles exhaust emissions inventory before and during APEC conference was developed based on bottom-up emissions inventory method. The results indicated that CO, NOx, HC and PM emissions of vehicle exhaust were reduced by 37.5%, 43.4%, 39.9% and 42.9% in the study area, respectively.

  10. Implications of the Temporal Resolution of Fire Emissions on Direct and Indirect Aerosol Effects

    NASA Astrophysics Data System (ADS)

    Darmenov, A.; Barahona, D.; Kim, K. M.; da Silva, A.; Colarco, P. R.; Govindaraju, R.

    2014-12-01

    Biomass burning is an important source of particulates and trace gases and a major element of the terrestrial carbon cycle. Well constrained emissions from open vegetation fires in both time and space are needed to model direct and indirect effect of biomass burning aerosols, homogeneous and heterogeneous chemistry in the atmosphere and perform credible integrated earth system analysis, climate and air pollution studies. However representing fires in regional and global numerical models is challenging because of the subgrid scales at which fire processes operate. An example of apparent discrepancy in scales is the use of monthly- or seasonal-mean fire emissions which given the stochastic nature of fires means that at certain spatial scales the temporal behavior of emissions becomes influenced by individual fire events and becomes more variable. The present study aims at investigating the impact of monthly-mean fire emissions on direct and indirect aerosol effects. Key element of our work is the use of fire radiative power (FRP) based emissions and a global fully interactive cloud-aerosol-radiation modeling system. We used the Goddard Earth Observing System Model, Version 5 (GEOS-5) with two moment cloud microphysics and explicit cloud droplet activation and ice nucleation. GEOS-5 is coupled with an online version of the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model. Biomass burning emissions used in this study are from the Quick Fire Emission Dataset (QFED) available daily at up to 0.1 degrees horizontal resolution. We performed experiments with daily-mean and monthly-mean QFED emissions at two degree horizontal resolutions and report differences in aerosol burden and radiative forcing, for example we found that regional differences of clear-sky aerosol direct radiative effect at the surface and at the top of the atmosphere in MAM and JJA can be as high as 4 Wm-2 and 3 Wm-2, respectively.

  11. Sensitivity of blackbody effective emissivity to wavelength and temperature: By genetic algorithm

    SciTech Connect

    Ejigu, E. K.; Liedberg, H. G.

    2013-09-11

    A variable-temperature blackbody (VTBB) is used to calibrate an infrared radiation thermometer (pyrometer). The effective emissivity (ε{sub eff}) of a VTBB is dependent on temperature and wavelength other than the geometry of the VTBB. In the calibration process the effective emissivity is often assumed to be constant within the wavelength and temperature range. There are practical situations where the sensitivity of the effective emissivity needs to be known and correction has to be applied. We present a method using a genetic algorithm to investigate the sensitivity of the effective emissivity to wavelength and temperature variation. Two matlab® programs are generated: the first to model the radiance temperature calculation and the second to connect the model to the genetic algorithm optimization toolbox. The effective emissivity parameter is taken as a chromosome and optimized at each wavelength and temperature point. The difference between the contact temperature (reading from a platinum resistance thermometer or liquid in glass thermometer) and radiance temperature (calculated from the ε{sub eff} values) is used as an objective function where merit values are calculated and best fit ε{sub eff} values selected. The best fit ε{sub eff} values obtained as a solution show how sensitive they are to temperature and wavelength parameter variation. Uncertainty components that arise from wavelength and temperature variation are determined based on the sensitivity analysis. Numerical examples are considered for illustration.

  12. How effective is greening policy in reducing GHG emissions from agriculture? Evidence from Italy.

    PubMed

    Solazzo, Roberto; Donati, Michele; Tomasi, Licia; Arfini, Filippo

    2016-12-15

    Agriculture contributes significantly to greenhouse gas (GHG) emissions, accounting for more than 10% of total CO2 emissions in the EU-28 area. The Common Agricultural Policy (CAP) plays an important role in promoting environmentally and climate friendly practices and needs to respond to the new environmental challenges by better integrating its objectives with other EU policies. In this respect, the recent CAP reform 2014-2020 made a further step, making a large part of direct payments conditional on new agricultural practices beneficial for the climate and the environment, i.e. "greening". In this study we estimate the potential environmental benefits from greening in terms of GHG emissions in four regions of Northern Italy, one of the major European agricultural areas in terms of emissions. The emissions were quantified and broken down into the three main GHGs (carbon dioxide, methane and nitrous oxide) per production process. This information was subsequently used in a Positive Mathematical Programming (PMP) farm-based model on more than 3,000 farms, to estimate the effects of greening on regional land use and its contribution in reducing the total emissions. The new agri-environmental constraints produce a modest abatement of total emissions of greenhouse gases (-1.5%) in the analyzed area. The model estimates a reduction in CO2 emissions of about 2%. Emissions from nitrous oxide show a decrease of 2.1% and the reduction in the methane is about 0.4% compared to the observed scenario. The process of "lightening" that affected the greening during the CAP negotiation has inevitably resulted in missing an opportunity to introduce a significant positive change of behaviour into agriculture, in line with the expectations and needs of society for EU agriculture as a provider of public goods.

  13. Effect of Biochar on Greenhouse Gas Emissions and Nitrogen Cycling in Laboratory and Field Experiments

    NASA Astrophysics Data System (ADS)

    Hagemann, Nikolas; Harter, Johannes; Kaldamukova, Radina; Ruser, Reiner; Graeff-Hönninger, Simone; Kappler, Andreas; Behrens, Sebastian

    2014-05-01

    The extensive use of nitrogen (N) fertilizers in agriculture is a major source of anthropogenic N2O emissions contributing 8% to global greenhouse gas emissions. Soil biochar amendment has been suggested as a means to reduce both CO2 and non-CO2 greenhouse gas emissions. The reduction of N2O emissions by biochar has been demonstrated repeatedly in field and laboratory experiments. However, the mechanisms of the reduction remain unclear. Further it is not known how biochar field-weathering affects GHG emissions and how agro-chemicals, such as the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP), that is often simultaneously applied together with commercial N-fertilizers, impact nitrogen transformation and N2O emissions from biochar amended soils. In order investigate the duration of the biochar effect on soil N2O emissions and its susceptibility to DMPP application we performed a microcosm and field study with a high-temperature (400 ° C) beech wood derived biochar (60 t ha-1 and 5 % (w/w) biochar in the field and microcosms, respectively). While the field site contained the biochar already for three years, soil and biochar were freshly mixed for the laboratory microcosm experiments. In both studies we quantified GHG emissions and soil nitrogen speciation (nitrate, nitrite, ammonium). While the field study was carried out over the whole vegetation period of the sunflower Helianthus annuus L., soil microcosm experiments were performed for up to 9 days at 28° C. In both experiments a N-fertilizer containing DMPP was applied either before planting of the sunflowers or at the beginning of soil microcosms incubation. Laboratory microcosm experiments were performed at 60% water filled pore space reflecting average field conditions. Our results show that biochar effectively reduced soil N2O emissions by up to 60 % in the field and in the soil microcosm experiments. No significant differences in N2O emission mitigation potential between field-aged and fresh

  14. [Lead emission amount from coal combustion and its environment effect in Xi'an City].

    PubMed

    Luo, Kunli; Wang, Douhu; Tan, Jianan; Wang, Lizheng; Feng, Fujian; Li, Ribang

    2002-01-30

    For study the lead emission amount from coal combustion and its environment effect, the lead content of coal, ash and cinder of power station and coal-fired boiler, the lead content of dusts in the period of heating time and the non-heating time in Xi'an City were studied in this paper. The results show that amount of lead emission from 1 ton coal combustion, which lead content in coal was 30 g, was 20 g in atmosphere. The rate of lead emission of coal combustion was about 66%. About 10 million tons of coal was straight burning every year in Xi'an City and suburb, those coal mainly come from Permo-Carboniferous coal in Weibei coal mine, Shaanxi, their average lead content was 30 mg/kg. So the total lead emission from coal combustion to atmosphere was about 200 t annually in Xi'an City.

  15. Jupiter's decameter and kilometer emissions: satellite effects and long term periodicities

    SciTech Connect

    St. Cyr, O.C.

    1985-01-01

    Results of observational studies of Jupiter's decameter (DAM) and kilometer (KOM) radio emissions are presented. The initial goal was to investigate the role of Jupiter's major satellites in modulating these sporadic emissions. Concepts of electromagnetic induction in planet-sized bodies are reviewed and the Jovian magnetosphere environment and the physical characteristics of the Galilean satellites and Amalthea are described. Since the phase of Io is known to modulate the DAM emissions, the author addresses the problem of orbital resonance among the Galilean satellites. When IO's influence in the emissions is eliminated from more than two decades of ground-based observation, no significant enhancements or deficiencies in the detection probability were found for the phases of Europa, Ganymede, or Callisto. A secondary goal was to search for long term periodicities and other effects in the ground-based DAM data. As expected, a strong tendency toward an increase or decrease, respectively, in D/sub E/ was found.

  16. Effect of flameholder pressure drop on emissions and performance of premixed-prevaporized combustors

    NASA Technical Reports Server (NTRS)

    Duerr, R. A.; Lyons, V. J.

    1983-01-01

    Parametric tests were conducted to determine the effects of flameholder pressure drop on the emissions and performance of lean premixed-prevaporized combustors. A conical flameholder mounted in a diverging duct was tested with two values of flameholder blockage. Emissions of nitrogen oxides, carbon monoxide, carbon dioxide, and unburned hydrocarbons were measured for combustor entrance conditions of 600 to 800 K air temperature, 0.3 MPa to 0.5 MPa pressure, and 20 m/sec to 35 m/sec reference velocity. Jet A fuel was injected at flow rates corresponding to an equivalence ratio range from 0.8 down to the lean stability limit. Emission results for the high-blockage flameholder were a substantial improvement over the low-blockage emission results. A correlation of combustion efficiency with flameholder pressure drop was developed for pressure drops less than 9 percent.

  17. [Effects of understory removal on soil greenhouse gas emissions in Carya cathayensis stands].

    PubMed

    Liu, Juan; Chen, Xue-shuang; Wu, Jia-sen; Jiang, Pei-kun; Zhou, Guo-mo; Li, Yong-fu

    2015-03-01

    CO2, N2O and CH4 are important greenhouse gases, and soils in forest ecosystems are their important sources. Carya cathayensis is a unique tree species with seeds used for high-grade dry fruit and oil production. Understory vegetation management plays an important role in soil greenhouse gases emission of Carya cathayensis stands. A one-year in situ experiment was conducted to study the effects of understory removal on soil CO2, N2O and CH4 emissions in C. cathayensis plantation by closed static chamber technique and gas chromatography method. Soil CO2 flux had a similar seasonal trend in the understory removal and preservation treatments, which was high in summer and autumn, and low in winter and spring. N2O emission occurred mainly in summer, while CH4 emission showed no seasonal trend. Understory removal significantly decreased soil CO, emission, increased N2O emission and CH4 uptake, but had no significant effect on soil water soluble organic carbon and microbial biomass carbon. The global warming potential of soil greenhouse gases emitted in the understory removal. treatment was 15.12 t CO2-e . hm-2 a-1, which was significantly lower than that in understory preservation treatment (17.04 t CO2-e . hm-2 . a-1).

  18. The market effectiveness of electricity reform: A case of carbon emissions trading market of Shenzhen city

    NASA Astrophysics Data System (ADS)

    Wang, Yongli; Wang, Gang; Zuo, Yi; Fan, Lisha; Xiao, Yao

    2017-03-01

    In the 13th Five-Year Plan, the Chinese government proposed to achieve the national carbon emission trading market established by 2017. The establishment of carbon emission trading market is the most important one in power reform, which helps to promote the power reform and achieve the goal of energy saving and emission reduction. As the bond of connecting environment energy issues and the economic development, carbon emissions trading market has become a hot research topic in the related fields, by market means, it incentive the lower cost subject emissions to undertake more reductions and therefore to benefit, the body of the high cost finished the task by buying quota reduction, to achieve the effect of having the least social total cost. Shenzhen has become the first city in China to start carbon trading pilot formally on June 16, 2013, online trading on June 18. The paper analyzes the market effectiveness of electricity reform in China, which takes carbon emissions trading market of Shenzhen city for example, and gives some suggestions for future development.

  19. Effect of temperature and humidity on formaldehyde emissions in temporary housing units.

    PubMed

    Parthasarathy, Srinandini; Maddalena, Randy L; Russell, Marion L; Apte, Michael G

    2011-06-01

    The effect of temperature and humidity on formaldehyde emissions from samples collected from temporary housing units (THUs) was studied. The THUs were supplied by the U.S. Federal Emergency Management Administration (FEMA) to families that lost their homes in Louisiana and Mississippi during the Hurricane Katrina and Rita disasters. On the basis of a previous study, four of the composite wood surface materials that dominated contributions to indoor formaldehyde were selected to analyze the effects of temperature and humidity on the emission factors. Humidity equilibration experiments were carried out on two of the samples to determine how long the samples take to equilibrate with the surrounding environmental conditions. Small chamber experiments were then conducted to measure emission factors for the four surface materials at various temperature and humidity conditions. The samples were analyzed for formaldehyde via high-performance liquid chromatography. The experiments showed that increases in temperature or humidity contributed to an increase in emission factors. A linear regression model was built using the natural log of the percent relative humidity (RH) and inverse of temperature (in K) as independent variables and the natural log of emission factors as the dependent variable. The coefficients for the inverse of temperature and log RH with log emission factor were found to be statistically significant for all of the samples at the 95% confidence level. This study should assist in retrospectively estimating indoor formaldehyde exposure of occupants of THUs.

  20. EFFECT OF TEMPERATURE AND HUMIDITY ON FORMALDEHYDE EMISSIONS IN TEMPORARY HOUSING UNITS

    SciTech Connect

    Parthasarathy, Srinandini; Maddalena, Randy L.; Russell, Marion L.; Apte, Michael G.

    2010-04-01

    The effect of temperature and humidity on formaldehyde emissions from samples collected from temporary housing units (THUs) was studied. The THUs were supplied by the U.S Federal Emergency Management Administration (FEMA) to families that lost their homes in Louisiana and Mississippi during the Hurricane Katrina and Rita disasters. Based on a previous study 1, 2, four of the composite wood surface materials that dominated contributions to indoor formaldehyde were selected to analyze the effects of temperature and humidity on the emission factors. Humidity equilibration experiments were carried out on two of the samples to determine how long the samples take to equilibrate with the surrounding environmental conditions. Small chamber experiments were then conducted to measure emission factors for the four surface materials at various temperature and humidity conditions. The samples were analyzed for formaldehyde via high performance liquid chromatography. The experiments showed that increases in temperature or humidity contributed to an increase in emission factors. A linear regression model was built using natural log of percentage relative humidity (RH) and inverse of temperature (in K) as predictor variables, and natural log of emission factors as the target variable. The coefficients of both inverse temperature and log relative humidity with log emission factor were found to be statistically significant for all the samples at the 95percent confidence level. This study should assist to retrospectively estimate indoor formaldehyde exposures of occupants of temporary housing units (THUs).

  1. The effects of plant diversity on nitrous oxide emissions in hydroponic microcosms

    NASA Astrophysics Data System (ADS)

    Sun, Hongying; Zhang, Chongbang; Song, Changchun; Chang, Scott X.; Gu, Baojing; Chen, Zhengxin; Peng, Changhui; Chang, Jie; Ge, Ying

    2013-10-01

    Previous studies have shown that plant diversity can improve the wastewater purification efficiency of constructed wetlands (CWs), but its effect on the nitrous oxide (N2O) emission in CWs has been unknown. To investigate the effect of plant diversity on the N2O emission, we established four plant species richness levels (each level containing 1, 2, 3 and 4 species, respectively) by using 96 hydroponic microcosms. Results showed that plant species richness enhanced the N2O emission, ranging from 27.1 to 115.4 μg N2O m-2 d-1, and improved nitrate removal (P < 0.001). The presence of Phalaris arundinacea within a given plant community increased the N2O emission (P < 0.001). The presence of Rumex japonicas had no influence on the N2O emissions (P > 0.05), but improved nitrogen removal (P < 0.001). Hence, our study highlights the importance of both plant species richness and species identity in mediating the N2O emission and nitrogen removal in CWs.

  2. Effect of fuels and domestic heating appliance types on emission factors of selected organic pollutants.

    PubMed

    Šyc, Michal; Horák, Jiří; Hopan, František; Krpec, Kamil; Tomšej, Tomáš; Ocelka, Tomáš; Pekárek, Vladimír

    2011-11-01

    This study reports on the first complex data set of emission factors (EFs) of selected pollutants from combustion of five fuel types (lignite, bituminous coal, spruce, beech, and maize) in six different domestic heating appliances of various combustion designs. The effect of fuel as well as the effect of boiler type was studied. In total, 46 combustion runs were performed, during which numerous EFs were measured, including the EFs of particulate matter (PM), carbon monoxide, polyaromatic hydrocarbons (PAH), hexachlorobenzene (HxCBz), polychlorinated dibenzo-p-dioxins and furans (PCDD/F), etc. The highest EFs of nonchlorinated pollutants were measured for old-type boilers with over-fire and under-fire designs and with manual stoking and natural draft. Emissions of the above-mentioned pollutants from modern-type boilers (automatic, downdraft) were 10 times lower or more. The decisive factor for emission rate of nonchlorinated pollutants was the type of appliance; the type of fuel plays only a minor role. Emissions of chlorinated pollutants were proportional mainly to the chlorine content in fuel, but the type of appliance also influenced the rate of emissions significantly. Surprisingly, higher EFs of PCDD/F from combustion of chlorinated bituminous coal were observed for modern-type boilers (downdraft, automatic) than for old-type ones. On the other hand, when bituminous coal was burned, higher emissions of HxCBz were found for old-type boilers than for modern-type ones.

  3. Effects of Biofuel and Variant Ambient Pressure on FlameDevelopment and Emissions of Gasoline Engine.

    NASA Astrophysics Data System (ADS)

    Hashim, Akasha; Khalid, Amir; Sapit, Azwan; Samsudin, Dahrum

    2016-11-01

    There are many technologies about exhaust emissions reduction for wide variety of spark ignition (SI) engine have been considered as the improvement throughout the combustion process. The stricter on legislation of emission and demands of lower fuel consumption needs to be priority in order to satisfy the demand of emission quality. Besides, alternative fuel such as methanol-gasoline blends is used as working fluid in this study due to its higher octane number and self-sustain concept which capable to contribute positive effect to the combustion process. The purpose of this study is to investigate the effects of methanol-gasoline fuel with different blending ratio and variant ambient pressures on flame development and emission for gasoline engine. An experimental study is carried towards to the flame development of methanol-gasoline fuel in a constant volume chamber. Schlieren optical visualization technique is a visual process that used when high sensitivity is required to photograph the flow of fluids of varying density used for captured the combustion images in the constant volume chamber and analysed through image processing technique. Apart from that, the result showed combustion burn rate increased when the percentage of methanol content in gasoline increased. Thus, high percentage of methanol-gasoline blends gave greater flame development area. Moreover, the emissions of CO, NOX and HC are performed a reduction when the percentage of methanol content in gasoline is increased. Contrarily, the emission of Carbon dioxide, CO2 is increased due to the combustion process is enhanced.

  4. The Effect of Natural Gas Supply on US Renewable Energy and Greenhouse Gas Emissions

    NASA Astrophysics Data System (ADS)

    Shearer, C.; Bistline, J.; Inman, M.; Davis, S. J.

    2014-12-01

    Increased use of natural gas has been promoted as a means of decarbonizing the US power sector, because of superior generator efficiency and lower CO2 emissions per unit of electricity than coal. We model the effect of different gas supplies on the US power sector and greenhouse gas (GHG) emissions. Across a range of climate policies, we find that more abundant natural gas decreases use of both coal and renewable energy technologies in the future. Without a climate policy, overall energy use also increases as the gas supply increases. With reduced deployment of lower-carbon renewable energies and increased electricity consumption, the effect of higher gas supplies on GHG emissions is small: cumulative emissions 2013-2055 in our high gas supply scenario are 2% less than in our low gas supply scenario, when there are no new climate policies and a methane leakage rate of 1.5% is assumed. Assuming leakage rates of 0 or 3% does not substantially alter this finding. In our results, only climate policies bring about a significant reduction in future CO2 emissions within the US electricity sector. Our results suggest that without strong limits on GHG emissions or policies that explicitly encourage renewable energy, more abundant natural gas may actually slow the process of decarbonization, primarily by delaying deployment of renewable energy technologies.

  5. Tectorial Membrane Morphological Variation: Effects upon Stimulus Frequency Otoacoustic Emissions

    PubMed Central

    Bergevin, Christopher; Velenovsky, David S.; Bonine, Kevin E.

    2010-01-01

    The tectorial membrane (TM) is widely believed to play an important role in determining the ear's ability to detect and resolve incoming acoustic information. While it is still unclear precisely what that role is, the TM has been hypothesized to help overcome viscous forces and thereby sharpen mechanical tuning of the sensory cells. Lizards present a unique opportunity to further study the role of the TM given the diverse inner-ear morphological differences across species. Furthermore, stimulus-frequency otoacoustic emissions (SFOAEs), sounds emitted by the ear in response to a tone, noninvasively probe the frequency selectivity of the ear. We report estimates of auditory tuning derived from SFOAEs for 12 different species of lizards with widely varying TM morphology. Despite gross anatomical differences across the species examined herein, low-level SFOAEs were readily measurable in all ears tested, even in non-TM species whose basilar papilla contained as few as 50–60 hair cells. Our measurements generally support theoretical predictions: longer delays/sharper tuning features are found in species with a TM relative to those without. However, SFOAEs from at least one non-TM species (Anolis) with long delays suggest there are likely additional micromechanical factors at play that can directly affect tuning. Additionally, in the one species examined with a continuous TM (Aspidoscelis) where cell-to-cell coupling is presumably relatively stronger, delays were intermediate. This observation appears consistent with recent reports that suggest the TM may play a more complex macromechanical role in the mammalian cochlea via longitudinal energy distribution (and thereby affect tuning). Although significant differences exist between reptilian and mammalian auditory biophysics, understanding lizard OAE generation mechanisms yields significant insight into fundamental principles at work in all vertebrate ears. PMID:20712989

  6. The effect of SST emissions on the earth's ozone layer

    NASA Technical Reports Server (NTRS)

    Whitten, R. C.; Turco, R. P.

    1974-01-01

    The work presented here is directed toward assessment of environmental effects of the supersonic transport (SST). The model used for the purpose includes vertical eddy transport and the photochemistry of the O-H-N system. It is found that the flight altitude has a pronounced effect on ozone depletion. The largest ozone reduction occurs for NO deposition above an altitude of 20 km.

  7. Application technique and slurry co-fermentation effects on ammonia, nitrous oxide, and methane emissions after spreading: II. Greenhouse gas emissions.

    PubMed

    Wulf, S; Maeting, M; Clemens, J

    2002-01-01

    The aim of this study was to investigate the effect of different application techniques on greenhouse gas emission from co-fermented slurry. Ammonia (NH3), nitrous oxide (N2O), and methane (CH4) emissions were measured in two field experiments with four different application techniques on arable and grassland sites. To gather information about fermentation effects, unfermented slurry was also tested, but with trail hose application only. Co-fermented slurry was applied in April at a rate of 30 m3 ha(-1). Measurements were made every 4 h on the first day after application and were continued for 6 wk with gradually decreasing sampling frequency. Methane emissions were <150 g C ha(-1) from co-fermentation products and seemed to result from dissolved CH4. Only in the grassland experiment were emissions from unfermented slurry significantly higher, with wetter weather conditions probably promoting CH4 production. Nitrous oxide emission was significantly increased by injection on arable and grassland sites two- and threefold, respectively. Ammonia emissions were smallest after injection or trail shoe application and are discussed in the preceding paper. We evaluated the climatic relevance of the measured gas emissions from the different application techniques based on the comparison of CO2 equivalents. It was evident that NH3 emission reduction, which can be achieved by injection, is at least compensated by increased N2O emissions. Our results indicate that on arable land, trail hose application with immediate shallow incorporation, and on grassland, trail shoe application, bear the smallest risks of high greenhouse gas emissions when fertilizing with co-fermented slurry.

  8. Isoprene in poplar emissions: effects on new particle formation and OH concentrations

    NASA Astrophysics Data System (ADS)

    Kiendler-Scharr, A.; Andres, S.; Bachner, M.; Behnke, K.; Broch, S.; Hofzumahaus, A.; Holland, F.; Kleist, E.; Mentel, T. F.; Rubach, F.; Springer, M.; Steitz, B.; Tillmann, R.; Wahner, A.; Schnitzler, J.-P.; Wildt, J.

    2011-08-01

    Stress-induced volatile organic compound (VOC) emissions from transgenic Grey poplar, modified in isoprene emission potential were used for the investigation of photochemical secondary organic aerosol (SOA) formation. Nucleation rates of up to 3600 cm-3 s-1 were observed in our experiments. In poplar, acute ozone stress induces the emission of a wide array of VOCs dominated by sesquiterpenes and aromatic VOCs. Constitutive light-dependent emission of isoprene ranged between 66 nmol m-2 s-1 in non-transgenic controls (wild type WT) and nearly zero (<0.5 nmol m-2 s-1) in isoprene emission-repressed lines (line RA22), respectively. In the presence of isoprene new particle formation was suppressed compared to non-isoprene containing VOC mixtures. Compared to isoprene/monoterpene systems emitted from other plants the suppression of nucleation by isoprene was less effective for the VOC mixture emitted from stressed poplar. This is explained by the observed high efficiency of new particle formation for emissions from stressed poplar. Direct measurements of OH in the reaction chamber revealed that the steady state concentration of OH is lower in the presence of isoprene than in the absence of isoprene, supporting the hypothesis that isoprenes' suppressing effect on nucleation is related to radical chemistry. In order to test whether isoprene contributes to SOA mass formation, fully deuterated isoprene (C5D8) was added to the stress-induced emission profile of an isoprene free poplar mutant. Mass spectral analysis showed that, despite the isoprene-induced suppression of particle formation, fractions of deuterated isoprene were incorporated into the SOA. A fractional mass yield of 2.3 % of isoprene was observed. Future emission changes due to land use and climate change may therefore affect both gas phase oxidation capacity and new particle number formation.

  9. Isoprene in poplar emissions: effects on new particle formation and OH concentrations

    NASA Astrophysics Data System (ADS)

    Kiendler-Scharr, A.; Andres, S.; Bachner, M.; Behnke, K.; Broch, S.; Hofzumahaus, A.; Holland, F.; Kleist, E.; Mentel, T. F.; Rubach, F.; Springer, M.; Steitz, B.; Tillmann, R.; Wahner, A.; Schnitzler, J.-P.; Wildt, J.

    2012-01-01

    Stress-induced volatile organic compound (VOC) emissions from transgenic Grey poplar modified in isoprene emission potential were used for the investigation of photochemical secondary organic aerosol (SOA) formation. In poplar, acute ozone stress induces the emission of a wide array of VOCs dominated by sesquiterpenes and aromatic VOCs. Constitutive light-dependent emission of isoprene ranged between 66 nmol m-2 s-1 in non-transgenic controls (wild type WT) and nearly zero (<0.5 nmol m-2 s-1) in isoprene emission-repressed plants (line RA22), respectively. Nucleation rates of up to 3600 cm-3 s-1 were observed in our experiments. In the presence of isoprene new particle formation was suppressed compared to non-isoprene containing VOC mixtures. Compared to isoprene/monoterpene systems emitted from other plants the suppression of nucleation by isoprene was less effective for the VOC mixture emitted from stressed poplar. This is explained by the observed high efficiency of new particle formation for emissions from stressed poplar. Direct measurements of OH in the reaction chamber revealed that the steady state concentration of OH is lower in the presence of isoprene than in the absence of isoprene, supporting the hypothesis that isoprenes' suppressing effect on nucleation is related to radical chemistry. In order to test whether isoprene contributes to SOA mass formation, fully deuterated isoprene (C5D8) was added to the stress-induced emission profile of an isoprene free poplar mutant. Mass spectral analysis showed that, despite the isoprene-induced suppression of particle formation, fractions of deuterated isoprene were incorporated into the SOA. A fractional mass yield of 2.3% of isoprene was observed. Future emission changes due to land use and climate change may therefore affect both gas phase oxidation capacity and new particle number formation.

  10. Effects of phosphogypsum and superphosphate on compost maturity and gaseous emissions during kitchen waste composting

    SciTech Connect

    Yang, Fan; Li, Guoxue; Shi, Hong; Wang, Yiming

    2015-02-15

    Highlights: • Effect of phosphogypsum and superphosphate on composting gas emissions was studied. • The reduction mechanisms of composting gas were clarified in this study. • No negative effect was caused on maturity with phosphogypsum and superphosphate. • CH{sub 4} and NH{sub 3} emission was decreased with phosphogypsum and superphosphate addition. • GHG decreased by 17.4% and 7.3% with phosphogypsum and superphosphate addition. - Abstract: This study investigated the effects of phosphogypsum and superphosphate on the maturity and gaseous emissions of composting kitchen waste. Two amended compost treatments were conducted using phosphogypsum and superphosphate as additives with the addition of 10% of initial raw materials (dry weight). A control treatment was also studied. The treatments were conducted under aerobic conditions in 60-L reactors for 35 days. Maturity indexes were determined, and continuous measurements of CH{sub 4}, N{sub 2}O, and NH{sub 3} were taken. Phosphogypsum and superphosphate had no negative effects on compost maturity, although superphosphate inhibited the temperature rise in the first few days. The addition of phosphogypsum and superphosphate drastically reduced CH{sub 4} emissions (by 85.8% and 80.5%, respectively) and decreased NH{sub 3} emissions (by 23.5% and 18.9%, respectively). However, a slight increase in N{sub 2}O emissions (by 3.2% and 14.8%, respectively) was observed. Composting with phosphogypsum and superphosphate reduced total greenhouse gas emissions by 17.4% and 7.3% respectively.

  11. Effect of water seal on reducing 1,3-dichloropropene emissions from different soil textures.

    PubMed

    McDonald, Jason A; Gao, Suduan; Qin, Ruijun; Hanson, Bradley D; Trout, Thomas J; Wang, Dong

    2009-01-01

    Soil physical conditions can affect diffusion, environmental fate, and efficacy of fumigants in soil disinfestation treatments. Water seals (applying water using sprinklers to soil following fumigation) can effectively reduce fumigant emissions from sandy loam soils. Soil column studies compared the effectiveness of water seals in reducing cis-1,3-dichloropropene (1,3-D) emissions from three different textured soils (loamy sand, sandy loam, and loam). Treatments included an untreated control, an initial water seal (9 mm water applied immediately before fumigant injection), and intermittent water seals (initial 9 mm water seal followed by 3 mm at 12 and 24 h). For the loamy sand, instead of the initial water seal treatment, a reduced-amount intermittent water seal (initial 3 mm water followed by 1 mm at 12 and 24 h) treatment was tested. Overall emission loss of 1,3-D from the control over 2 wk was 56% for the loamy sand, 51% for the sandy loam, and 43% for the loam. The initial water seal reduced total 1,3-D emissions to 46% in the sandy loam and 31% in the loam. The intermittent water seals reduced emission loss to 26% for the loamy sand, 41% for the sandy loam, and 21% for the loam. The reduced-amount intermittent water seal for loamy sand had little effect. Low emission loss was associated with high surface soil water content. None of the water applications reduced gaseous fumigant concentrations. Results indicate that water seal techniques may be able to effectively reduce emissions for different soil textures without reducing fumigant concentration in the soil.

  12. The effect of fuel processes on heavy duty automotive diesel engine emissions

    SciTech Connect

    Reynolds, E.G.

    1995-12-31

    The effect of fuel quality on exhaust emissions from 2 heavy duty diesel engines has been measured over the ECE R49 test cycle. The engines were selected to represent technologies used to meet Euro 1 and 2 emission standards (1992/93 and 1995/96); engines 1 and 2 respectively. The test fuels were prepared by a combination of processing, blending and additive treatment. When comparing the emissions from engines 1 and 2, using base line data generated on the CEC reference fuel RF73-T-90, engine technology had the major effect on emission levels. Engine 2 reduced both particulate matter (PM) and carbon monoxide levels by approximately 50%, with total hydrocarbon (THC) being approximately 75% lower. Oxides of nitrogen levels were similar for both engines. The variations in test fuel quality had marginal effects on emissions, with the two engines giving directionally opposite responses in some cases. For instance, there was an effect on CO and NOx but where one engine showed a reduction the other gave an increase. There were no significant changes in THC emissions from either engine when operating on any of the test fuels. When the reference fuel was hydrotreated, engine 1 showed a trend towards reduced particulate and NOx but with CO increasing. Engine 2 also showed a trend for reduced particulate levels, with an increase in NOx and no change in CO. Processing to reduce the final boiling point of the reference fuel showed a trend towards reduced particulate emissions with CO increasing on engine 1 but decreasing on engine 2.

  13. Mechanisms and modeling of the effects of additives on the nitrogen oxides emission

    NASA Technical Reports Server (NTRS)

    Kundu, Krishna P.; Nguyen, Hung Lee; Kang, M. Paul

    1991-01-01

    A theoretical study on the emission of the oxides of nitrogen in the combustion of hydrocarbons is presented. The current understanding of the mechanisms and the rate parameters for gas phase reactions were used to calculate the NO(x) emission. The possible effects of different chemical species on thermal NO(x), on a long time scale were discussed. The mixing of these additives at various stages of combustion were considered and NO(x) concentrations were calculated; effects of temperatures were also considered. The chemicals such as hydrocarbons, H2, CH3OH, NH3, and other nitrogen species were chosen as additives in this discussion. Results of these calculations can be used to evaluate the effects of these additives on the NO(x) emission in the industrial combustion system.

  14. Effect of smelter emission reductions on children's blood lead levels.

    PubMed

    Hilts, Steven R

    2003-02-15

    Trail, British Columbia has been the site of an active lead-zinc smelter for approximately 95 years. Since 1989, the community has been monitoring blood lead levels in children, studying exposure pathways and conducting comprehensive education and case management programs. From 1989 through 1996, mean blood lead levels of pre-school children declined at an average rate of 0.6 microg/dl per year. From 1996 to 1999, mean blood lead levels fell at an average rate of 1.8 microg/dl per year, from 11.5 in 1996 to 5.9 in 1999. The recent rapid decline appears to be mainly attributable to the start-up of a new lead smelter using modern flash-smelting technology in May of 1997. In 1998, the annual arithmetic mean air lead level in Trail was 0.28 microg/m(3), compared with 1.1 microg/m(3) in 1996. Reductions of approximately 50% were observed in lead loadings and concentrations in outdoor dustfall, street dust and indoor dustfall after smelter emissions were reduced. Slight reductions (statistically insignificant) have been observed in carpet dust and soil lead concentrations. During the summer of 2001, the smelting and refining operations at Trail were shut down completely for 3 months. During this period, average air lead levels in Trail dropped to 0.03 microg/m(3). The average blood lead level in Trail pre-school children at the end of the shutdown was 4.7 microg/dl. These results challenge prevailing theories about the relative importance of various environmental lead sources. For example, the US EPA Integrated Biokinetic Uptake Model for Lead (IEUBK), with its emphasis on soil concentrations, would not have predicted the dramatic decline in children's blood lead levels seen in Trail following the reductions in air lead levels. The Trail experience suggests that increased attention should be paid to the importance of active sources of highly bioavailable and mobile lead bearing dusts.

  15. Effects of solid barriers on dispersion of roadway emissions

    EPA Science Inventory

    Several studies have found that exposure to traffic-generated air pollution is associated with several adverse health effects. Field studies, laboratory experiments, and numerical simulations indicate that roadside barriers represent a practical method of mitigating the impact of...

  16. Determination of the Effects of Speed, Temperature, and Fuel Factors on Exhaust Emissions

    NASA Astrophysics Data System (ADS)

    Chou, Chia-Yang David

    1995-11-01

    This study provided a comprehensive approach to examining the relative significance and possible synergistic effects of speed, temperature, and fuel on mobile source emissions modeling. Eleven passenger vehicles from three fuel delivery system control groups were tested, namely, three from carburetor (CARBU), three from throttle body injection (TBI), and five from multi-port fuel injection (MPFI) group. A minimum of 90 tests were conducted on each vehicle with a random combination of three fuel types (Phase 1, Phase 2, and Indolene), three temperatures (50 F, 75 F, and 100 F), and ten speed cycles. Each vehicle was repeated for ten speed cycles (75 F and Indolene). In general, exhaust emissions descended in the order of CARBU, TBI, and MPFI. All vehicles in the CARBU group contained a "dead" catalyst, which probably explained why vehicles in CARBU were "high emitters.". Results from the paired t-test indicated that exhaust emissions difference between Phase 1 and Phase 2 fuels for all vehicles was significant. The net exhaust emissions reduction of Phase 2 over Phase 1 fuel for HC and NOx was 21% and 12%, respectively; which is in good agreements with the CARB projected 17% HC (including evaporative and exhaust emissions) and 11% CO emissions reduction based on 1996 calendar year when Phase 2 fuel is introduced. Temperature had minimal effects on exhaust emissions especially the test cycles were in hot-stabilized mode. Nevertheless, exhaust emissions from cold-start mode were higher than hot-start mode because the catalyst had not reached to optimal operating temperature during the cold-start mode. The relative contributions of speed, temperature, and fuel to exhaust emissions were determined using analysis of variance (ANOVA) and it was found interaction terms among fuel, speed, and temperature were statistically insignificant. Individually, the temperature and fuel factor played a minor role in exhaust emission modeling. Speed and vehicle type were the two

  17. Effects of Drought Stress and Ozone Exposure on Isoprene Emissions from Oak Seedlings in Texas

    NASA Astrophysics Data System (ADS)

    Madronich, M. B.; Harte, A.; Schade, G. W.

    2014-12-01

    Isoprene is the dominant hydrocarbon emitted by plants to the atmosphere with an approximate global emission of 550 Tg C yr-1. Isoprene emission studies have elucidated plants' isoprene production capacity, and the controlling factors of instantaneous emissions. However, it is not yet well understood how long-term climatic factors such as drought and increasing ozone concentrations affect isoprene emission rates. Drought reduces photosynthetic activity and is thus expected to reduce isoprene emission rate, since isoprene production relies on photosynthates. On the other hand, ozone is also known to negatively affect photosynthesis rates, but can instead increase isoprene emissions. These apparent inconsistencies and a lack of experimental data make it difficult to accurately parameterize isoprene emission responses to changing environmental conditions. The objective of this work is to reduce some of these uncertainties, using oak seedlings as a study system. Our project focuses on isoprene emission responses of oak trees to typical summer drought and high ozone conditions in Texas. We report on experiments conducted using a laboratory whole-plant chamber and leaf-level data obtained from greenhouse-grown seedlings. The chamber experiment studied the effects of ozone and drought on isoprene emissions from >3 year old oak seedlings under controlled conditions of photosynthetically active radiation (PAR), temperature, soil-moisture and the chamber's air composition. Stress in plants was induced by manipulating potted soil-moisture and ozone concentration in the chamber. The greenhouse study focused on understanding the effects of drought under Texas climatic conditions. For this study we used two year old seedlings of water oak (Quercus nigra) and post oak (Quercus stellata). Temperature, humidity and light in the greenhouse followed local conditions. Leaf-level conductance, photosynthesis measurements and isoprene sampling were carried out under controlled leaf

  18. The long-wavelength thermal emission of the Pluto-Charon system from Herschel observations. Evidence for emissivity effects

    NASA Astrophysics Data System (ADS)

    Lellouch, E.; Santos-Sanz, P.; Fornasier, S.; Lim, T.; Stansberry, J.; Vilenius, E.; Kiss, Cs.; Müller, T.; Marton, G.; Protopapa, S.; Panuzzo, P.; Moreno, R.

    2016-04-01

    Thermal observations of the Pluto-Charon system acquired by the Herschel Space Observatory in February 2012 are presented. They consist of photometric measurements with the PACS and SPIRE instruments (nine visits to the Pluto system each), covering six wavelengths from 70 to 500 μm altogether. The thermal light curve of Pluto-Charon is observed in all filters, albeit more marginally at 160 and especially 500 μm. Putting these data into the context of older ISO, Spitzer and ground-based observations indicates that the brightness temperature (TB) of the system (rescaled to a common heliocentric distance) drastically decreases with increasing wavelength, from ~53 K at 20 μm to ~35 K at 500 μm, and perhaps ever less at longer wavelengths. Considering a variety of diurnal and/or seasonal thermophysical models, we show that TB values of 35 K are lower than any expected temperature for the dayside surface or subsurface of Pluto and Charon, implying a low surface emissivity. Based on multiterrain modeling, we infer a spectral emissivity that decreases steadily from 1 at 20-25 μm to ~0.7 at 500 μm. This kind of behavior is usually not observed in asteroids (when proper allowance is made for subsurface sounding), but is found in several icy surfaces of the solar system. We tentatively identify that a combination of a strong dielectric constant and a considerable surface material transparency (typical penetration depth ~1 cm) is responsible for the effect. Our results have implications for the interpretation of the temperature measurements by REX/New Horizons at 4.2 cm wavelength. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  19. Effects of bypass system on PCDD/F emission and chlorine circulation in cement kilns.

    PubMed

    Zhan, Ming-Xiu; Fu, Jianying; Chen, Tong; Li, Yeqing; Zhang, Jiang; Li, Xiao-Dong; Yan, Jian-Hua; Buekens, Alfons

    2016-10-01

    A bypass at the kiln inlet allows the effective reduction of alkali chloride cycles and thus perhaps affects the emission of PCDD/Fs. Effects of bypass system on PCDD/F emission and chlorine circulation were studied in two typical dry cement kilns with 5000 ton/day clinker capacity in China and named CK1 and CK2, respectively. Firstly, the emission level of PCDD/Fs with the operation of bypass system was estimated in CK1, to certify that bypass system has a perfect adaption to the cement kiln regarding the PCDD/F emission even with the refuse derived fuel (RDF) as the replacement of fuel. On the other hand, the operating conditions in the CK2 were scrutinised by monitoring the concentrations of SO2, NH3 and HCl. In addition, the characteristics of raw meal, clinker, bag filter ash and bypass ash were also investigated by Energy Dispersive Spectrometer (EDS), metal and chlorine analysis. The balance of chlorine showed that 18 % of the possible accumulated chlorine could be ejected from the cement kiln system when 2 % of kiln exhaust gas was extracted. Furthermore, the emission level of PCDD/Fs in the main flue gas also decreased from 0.037 ± 0.035 ng I-TEQ/Nm(3) to 0.019 ± 0.007 ng I-TEQ/Nm(3) with a reduction efficiency of 48.2 %. Most importantly, PCDD/F emission from the bypass system was proven to have rather minor effect on the total emission factor. The congener distributions of PCDD/Fs were also analysed in the flue gas and fly ash, before and after application of bypass system, to find cues to the formation mechanism.

  20. Effects of signal light on the fuel consumption and emissions under car-following model

    NASA Astrophysics Data System (ADS)

    Tang, Tie-Qiao; Yi, Zhi-Yan; Lin, Qing-Feng

    2017-03-01

    In this paper, a car-following model is utilized to study the effects of signal light on each vehicle's fuel consumption, CO, HC and NOX. The numerical results show that each vehicle's fuel consumption and emissions are influenced by the signal light and that the effects are related to the green split of the signal light and the vehicle's time headway at the origin, which can help drivers adjust their micro driving behavior on the road with a signal light to reduce their fuel consumption and emissions.

  1. High performance field emission and Nottingham effect observed from carbon nanotube yarn

    NASA Astrophysics Data System (ADS)

    Choi, Young Chul; Kang, Jun-Tae; Park, Sora; Go, Eunsol; Jeon, Hyojin; Kim, Jae-Woo; Jeong, Jin-Woo; Park, Kyung-Ho; Song, Yoon-Ho

    2017-02-01

    Vertically aligned CNTs were synthesized on a four inch wafer, followed by the preparation of a CNT yarn. The yarn emitter was found to have an extremely high field enhancement factor, which was confirmed to have originated from multi-stage effect. In addition to superb field emission characteristics, the energy exchange during field emission, called Nottingham effect, was observed from the CNT yarn emitter. A CNT yarn was attached to the thermistor whose resistance depends on temperature. Then, the change of resistance was monitored during the field emission, which enabled us to calculate the energy exchange. It was found that the observed heating originated from both Nottingham and Joule heating. Nottingham heating was dominant at low current region while Joule heating became larger contribution at high current region. Very large Nottingham region of up to 33.35 mA was obtained, which is due presumably to the high performance field emission characteristics of a CNT yarn. This is believed to be an important observation for developing reliable field emission devices with suppressed Joule heating effect.

  2. Effective Suppression of Methane Emission by 2-Bromoethanesulfonate during Rice Cultivation

    PubMed Central

    Waghmode, Tatoba R.; Haque, Md. Mozammel; Kim, Sang Yoon; Kim, Pil Joo

    2015-01-01

    2-bromoethanesulfonate (BES) is a structural analogue of coenzyme M (Co-M) and potent inhibitor of methanogenesis. Several studies confirmed, BES can inhibit CH4 prodcution in rice soil, but the suppressing effectiveness of BES application on CH4 emission under rice cultivation has not been studied. In this pot experiment, different levels of BES (0, 20, 40 and 80 mg kg-1) were applied to study its effect on CH4 emission and plant growth during rice cultivation. Application of BES effectively suppressed CH4 emission when compared with control soil during rice cultivation. The CH4 emission rates were significantly (P<0.001) decreased by BES application possibly due to significant (P<0.001) reduction of methnaogenic biomarkers like Co-M concentration and mcrA gene copy number (i.e. methanogenic abunadance). BES significantly (P<0.001) reduced methanogen activity, while it did not affect soil dehydrogenase activity during rice cultivation. A rice plant growth and yield parameters were not affected by BES application. The maximum CH4 reduction (49% reduction over control) was found at 80 mg kg-1 BES application during rice cultivation. It is, therefore, concluded that BES could be a suitable soil amendment for reducing CH4 emission without affecting rice plant growth and productivity during rice cultivation. PMID:26562416

  3. The size and range effect: lifecycle greenhouse gas emissions of electric vehicles

    NASA Astrophysics Data System (ADS)

    Ager-Wick Ellingsen, Linda; Singh, Bhawna; Hammer Strømman, Anders

    2016-05-01

    The primary goal of this study is to investigate the effect of increasing battery size and driving range to the environmental impact of electric vehicles (EVs). To this end, we compile cradle-to-grave inventories for EVs in four size segments to determine their climate change potential. A second objective is to compare the lifecycle emissions of EVs to those of conventional vehicles. For this purpose, we collect lifecycle emissions for conventional vehicles reported by automobile manufacturers. The lifecycle greenhouse gas emissions are calculated per vehicle and over a total driving range of 180 000 km using the average European electricity mix. Process-based attributional LCA and the ReCiPe characterisation method are used to estimate the climate change potential from the hierarchical perspective. The differently sized EVs are compared to one another to find the effect of increasing the size and range of EVs. We also point out the sources of differences in lifecycle emissions between conventional- and electric vehicles. Furthermore, a sensitivity analysis assesses the change in lifecycle emissions when electricity with various energy sources power the EVs. The sensitivity analysis also examines how the use phase electricity sources influences the size and range effect.

  4. Effect of Alignment on Polarized Infrared Emission from Polycyclic Aromatic Hydrocarbons

    NASA Astrophysics Data System (ADS)

    Hoang, Thiem

    2017-04-01

    Polarized emission from polycyclic aromatic hydrocarbons (PAHs) potentially provides a new way to test the basic physics of the alignment of ultrasmall grains. In this paper, we present a new model of polarized PAH emission that takes into account the effect of PAH alignment with the magnetic field. We first generate a large sample of the grain angular momentum {\\boldsymbol{J}} by simulating the alignment of PAHs due to resonance paramagnetic relaxation that accounts for various interaction processes. We then calculate the polarization level of the PAH emission features for the different phases of the interstellar medium, including the cold neutral medium (CNM), reflection nebulae (RNe), and photodissociation regions. We find that a moderate degree of PAH alignment can significantly enhance the polarization degree of the PAH emission compared to the previous results obtained with randomly oriented angular momentum. In particular, we find that the smallest negatively charged PAHs in RNe can be excited to slightly suprathermal rotation due to enhanced ion collisional excitation, resulting in an increase of the polarization with the ionization fraction. Our results suggest that an RN is the most favorable environment in which to observe polarized PAH emission and to test the alignment physics of nanoparticles. Finally, we present an explicit relationship between the polarization level of PAH emission and the degree of external alignment for the CNM and RNe. The obtained relationship will be particularly useful for testing the alignment physics of PAHs in future observations.

  5. Effects of fuel type, driving cycle, and emission status on in-use vehicle exhaust reactivity.

    PubMed

    Ho, J; Winer, A M

    1998-07-01

    The introduction of reformulated gasolines significantly reduced exhaust hydrocarbon (HC) mass emissions, but few data are available concerning how these new fuels affect exhaust reactivity. Similarly, while it is well established that high-emitting vehicles contribute a significant portion of total mobile source HC mass emissions, it is also important to evaluate the exhaust reactivity from these vehicles. The objective of this study was to evaluate the relative influence on in-use vehicle exhaust reactivity of three critical factors: fuel, driving cycle, and vehicle emission status. Nineteen in-use vehicles were tested with seven randomly assigned fuel types and two driving cycles: the Federal Test Procedure (FTP) and the Unified Cycle (UC). Total exhaust reactivity was not statistically different between the FTP and UC cycles but was significantly affected by fuel type. On average, the exhaust reactivity for California Phase 2 fuel was the lowest (16% below the highest fuel type) among the seven fuels tested for cold start emissions. The average exhaust reactivity for high-emitting vehicles was significantly higher for hot stabilized (11%) and hot start (15%) emissions than for low-emitting vehicles. The exhaust reactivities for the FTP and UC cycles for light-end HCs and carbonyls were significantly different for the hot stabilized mode. There was a significant fuel effect on the mean specific reactivity (SR) for the mid-range HCs, but not for light-end HCs or carbonyls, while vehicle emission status affected the mean SR for all three HC compound classes.

  6. Effects of temperature, water content and nitrogen fertilisation on emissions of nitrous oxide by soils

    NASA Astrophysics Data System (ADS)

    Smith, K. A.; Thomson, P. E.; Clayton, H.; Mctaggart, I. P.; Conen, F.

    Nitrous oxide emissions were measured from several grassland and arable soils in the field, and from two of these soils and a forest soil transferred in large monoliths to a greenhouse. The effects of fertiliser N additions and of soil water content and temperature were investigated. Emissions were in the order grazed grassland>grassland cut for conservation>potatoes>cereal crops, and generally were higher than those from temperate natural ecosystems. Based on these data, agricultural soils constitute the major soil source of N 2O in the U.K. The highest emission recorded was 8 kg N 2O-N ha -1 over 10 months, from a grazed grassland site. Emissions varied from year to year, depending particularly on rainfall at the time of fertilisation. When soil mineral N was not limiting, exponential relationships between N 2O flux and both water-filled pore space (WFPS) and temperature were observed. The Q10 value for a sandy loam was 1.6, but ranged up to 12 for a clay loam soil at high WFPS. The high values were attributed to the increase in anaerobic zones where denitrification could take place, as respiratory demand for O 2 increased. A forest soil (peaty gley) showed an optimum water potential for N 2O emission. Diurnal fluctuations in emissions were associated with diurnal cycles in soil temperature, but with varying time lags, which could be explained by the N 2O being produced at different depths.

  7. Effect of fuel aromatic content on PAH emission from a heavy-duty diesel engine.

    PubMed

    Mi, H H; Lee, W J; Chen, C B; Yang, H H; Wu, S J

    2000-12-01

    Polycyclic aromatic hydrocarbons (PAHs) emission tests for a heavy-duty diesel engine fueled with blend base diesel fuel by adding batch fractions of poly-aromatic and mono-aromatic hydrocarbons, Fluorene and Toluene, respectively, were simulated to five steady-state modes by a DC-current dynamometer with fully automatic control system. The main objective of this study is to investigate the effect of total aromatic content and poly-aromatic content in diesel fuels on PAH emission from the HDD engine exhaust under these steady-state modes. The results of this study revealed that adding 3% and 5% (fuel vol%) Fluorene in the diesel fuel increases the amount of total-PAH emission by 2.6 and 5.7 times, respectively and increases the amount of Fluorene emission by 52.9 and 152 times, respectively, than no additives. However, there was no significant variation of PAH emission by adding 10% (vol%) of Toluene. To regulate the content of poly-aromatic content in diesel fuel, in contrast to the total aromatic content, will be more suitable for the management of PAH emission.

  8. Laboratory-scale measurements and simulations of effect of application methods on soil methyl bromide emission

    SciTech Connect

    Gan, J.; Yates, S.R.; Spencer, W.F.

    1997-01-01

    Methyl bromide (bromomethane, MeBr), which originates from the oceans, fumigation, and a few other sources, is reportedly contributing to the ozone depletion in the stratosphere. Due to the heavy reliance on this fumigant in the production of many crops, it is of particular importance to accurately quantify the atmospheric input of MeBr arising from agricultural uses, and develop feasible measures to minimize these emissions. In this study, we determined the effect of two important application variables, surface tarp and injection depth, on MeBr transport and transformation in the soil and its emission from the soil surface under controlled conditions. Following 20- and 30-cm injections, covering the soil surface with 1-mil (0.025 mm) high-density polyethylene film resulted in an average of 48% reduction in MeBr emission. Increasing the injection depth from 20 to 60 cm caused a decrease in MeBr emission of 54% under untarped conditions and 40% under tarped conditions. The influence of application methods on MeBr atmospheric emissions should be considered when estimating the contribution of agricultural fumigation to the overall atmospheric MeBr burden on a global scale. The results also indicate that MeBr emission after soil fumigation may be substantially minimized by using surface tarpaulins and deep injections. 34 refs., 5 figs., 1 tab.

  9. Effect of Biodiesel Fuels on Real-World Emissions of Passenger Locomotives.

    PubMed

    Graver, Brandon M; Frey, H Christopher; Hu, Jiangchuan

    2016-11-01

    Few data are available regarding the effect of biodiesel on exhaust emission rates of two-stroke engines used in many passenger locomotives. Using a portable emissions measurement system (PEMS), duty cycle average nitrogen oxides (NOx), hydrocarbons (HC), carbon monoxide (CO), particulate matter (PM), and carbon dioxide (CO2) emission rates were measured for three locomotives operating on ultra-low sulfur diesel (ULSD) and soy-based B10, B20, and B40 biodiesel blends. Measurements were conducted in the rail yard (RY) and over-the-rail (OTR) during passenger service. Compared to ULSD, B20 biodiesel had statistically significant average emission rate reductions in the RY of 58% for CO, 45% for PM, and 6% CO2 and OTR of 59% for HC, 50% for CO, 26% for PM, and 5% for CO2. The average differences in NOx emission rates for both the RY and OTR, and HC in the RY, were not statistically significant. The OTR findings typically agreed qualitatively with the RY findings; however, OTR provides a better basis for estimating the real-world impact of fuel switching. The results indicate substantial potential to reduce in-use locomotive emissions for existing older locomotives, with the exception of NOx.

  10. Effects of diesel engine speed and water content on emission characteristics of three-phase emulsions.

    PubMed

    Lin, Cherng-Yuan; Wang, Kuo-Hua

    2004-01-01

    The effects of water content of three-phase emulsions and engine speed on the combustion and emission characteristics of diesel engines were investigated in this study. The results show that a larger water content of water-in oil (W/O) and oil-in-water-in-oil (O/W/O) emulsion caused a higher brake specific fuel consumption (bsfc) value and a lower O2, as well as a lower NOx emission, but a larger CO emission. The increase in engine speed resulted in an increase of bsfc, exhaust gas temperature, fuel-to-air ratio, CO2 emission and a decrease of NOx, CO emission, and smoke opacity. Because of the physical structural differences, the three-phase O/W/O emulsions were observed to produce a higher exhaust gas temperature, a higher emulsion viscosity and a lower CO emission, in comparison with that of the two-phase W/O emulsion. In addition, the use of W/O emulsions with water content larger than 20% may cause diesel engines to shut down earlier than those running on O/W/O emulsions with the same water content. Hence, it is suggested that the emulsions with water content larger than 20% are not suitable for use as alternative fuel for diesel engines.

  11. The effect of temperature and moisture on trace gas emissions from deciduous and coniferous leaf litter

    NASA Astrophysics Data System (ADS)

    Gritsch, Christine; Egger, Florian; Zehetner, Franz; Zechmeister-Boltenstern, Sophie

    2016-05-01

    The forest litter layer lies at the boundary between soil and atmosphere and is a major factor in biogeochemical cycles. While there are several studies on how the litter layer controls soil trace gas emissions, litter emissions itself are less well understood, and it is still unclear how important gases respond to changing temperature and moisture. In order to assess leaf litter gas exchange, we conducted laboratory incubation experiments in which the full set of climate relevant gases, i.e., carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), and nitric oxide (NO) coming from deciduous and coniferous leaf litter were measured at five temperatures and seven moisture contents. In addition, we compared litter and soil from different origin in terms of temperature/moisture responses of gas fluxes and investigated possible interactions between the two climate factors. Deciduous litter emitted more CO2 (up to 335 mg CO2-C kg-1 h-1) than coniferous litter, whereas coniferous litter released maximum amounts of NO (207 µg NO-N kg-1 h-1). N2O was only emitted from litter under very moist and warm conditions (>70% wet weight, >10°C). CH4 emissions were close to zero. Temperature sensitivities of litter emissions were generally lower than for soil emissions. Nevertheless, wet and warm conditions always enhanced litter emissions, suggesting a strong feedback effect of the litter layer to predicted future climate change.

  12. Effect of first and second generation biodiesel blends on engine performance and emission

    NASA Astrophysics Data System (ADS)

    Azad, A. K.; Rasul, M. G.; Bhuiya, M. M. K.; Islam, Rubayat

    2016-07-01

    The biodiesel is a potential source of alternative fuel which can be used at different proportions with diesel fuel. This study experimentally investigated the effect of blend percentage on diesel engine performance and emission using first generation (soybean) and second generation (waste cooking) biodiesel. The characterization of the biodiesel was done according to ASTM and EN standards and compared with ultralow sulfur diesel (ULSD) fuel. A multi-cylinder test bed engine coupled with electromagnetic dynamometer and 5 gas analyzer were used for engine performance and emission test. The investigation was made using B5, B10 and B15 blends for both biodiesels. The study found that brake power (BP) and brake torque (BT) slightly decreases and brake specific fuel consumption (BSFC) slightly increases with an increase in biodiesel blends ratio. Besides, a significant reduction in exhaust emissions (except NOx emission) was found for both biodiesels compared to ULSD. Soybean biodiesel showed better engine performance and emissions reduction compared with waste cooking biodiesel. However, NOx emission for B5 waste cooking biodiesel was lower than soybean biodiesel.

  13. Effect of synthesis parameters on morphology of polyaniline (PANI) and field emission investigation of PANI nanotubes

    NASA Astrophysics Data System (ADS)

    Bankar, Prashant K.; Patil, Sandip S.; More, Mahendra A.

    2015-06-01

    Polyaniline (PANI) nanostructures have been synthesized by simple chemical oxidation route at different monomer concentration along with variation in synthesis temperature. The effect of variation of synthesis parameters has been revealed using different characterization techniques. The structural and morphological characterization of the synthesized PANI nanostructures was carried out by scanning electron microscopy (SEM), transmission electron microscopy (TEM), whereas Fourier Transform Infrared spectroscopy (FTIR) has been used to reveal the chemical properties. With the variation in the synthesis temperature and monomer concentration, various morphologies characterized by formation of PANI nanoparticles, nanofibres, nanotubes and nanospheres, are revealed from the SEM analysis. The FTIR analysis reveals the formation of conducting state of PANI under prevailing experimental conditions. The field emission investigation of the conducting PANI nanotubes was performed in all metal UHV system at base pressure of 1x10-8 mbar. The turn on field required to draw emission of 1 nA current was observed to be ˜ 2.2 V/μm and threshold field (corresponding to emission current density of 1 µA/cm2) was found to be 3.2 V/μm. The emission current was observed to be stable for more than three hours at a preset value 1 µA. The simple synthesis route and good field emission characteristics indicate potential of PANI nanofibres as a promising emitter for field emission based micro/nano devices.

  14. [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.

  15. Sulfur Dioxide Emissions and Market Effects under the Clean Air Act Acid Rain Program.

    PubMed

    Zipper, Carl E; Gilroy, Leonard

    1998-09-01

    The Clean Air Act Amendments of 1990 (CAAA90) established a national program to control sulfur dioxide (SO2) emissions from electricity generation. CAAA90's market-based approach includes trading and banking of Soumissions allowances. We analyzed data describing electric utility SO2 emissions in 1995, the first year of the program's Phase I, and market effects over the 1990-1995 period. Fuel switching and flue-gas desulfurization were the dominant means used in 1995 by targeted generators to reduce emissions to 51% of 1990 levels. Flue-gas desulfur-ization costs, emissions allowance prices, low-sulfur coal prices, and average sulfur contents of coals shipped to electric utilities declined over the 1990-1995 period. Projections indicate that 13-15 million allowances will have been banked during the program's Phase I, which ends in 1999, a quantity expected to last through the first decade of the program's stricter Phase II controls. In 1995, both allowance prices and SO2 emissions were below pre-CAAA90 expectations. The reduction of SO2 emissions beyond pre-CAAA90 expectations, combined with lower-than-expected allowance prices and declining compliance costs, can be viewed as a success for market-based environmental controls.

  16. Effect of synthesis parameters on morphology of polyaniline (PANI) and field emission investigation of PANI nanotubes

    SciTech Connect

    Bankar, Prashant K.; More, Mahendra A.; Patil, Sandip S.

    2015-06-24

    Polyaniline (PANI) nanostructures have been synthesized by simple chemical oxidation route at different monomer concentration along with variation in synthesis temperature. The effect of variation of synthesis parameters has been revealed using different characterization techniques. The structural and morphological characterization of the synthesized PANI nanostructures was carried out by scanning electron microscopy (SEM), transmission electron microscopy (TEM), whereas Fourier Transform Infrared spectroscopy (FTIR) has been used to reveal the chemical properties. With the variation in the synthesis temperature and monomer concentration, various morphologies characterized by formation of PANI nanoparticles, nanofibres, nanotubes and nanospheres, are revealed from the SEM analysis. The FTIR analysis reveals the formation of conducting state of PANI under prevailing experimental conditions. The field emission investigation of the conducting PANI nanotubes was performed in all metal UHV system at base pressure of 1x10{sup −8} mbar. The turn on field required to draw emission of 1 nA current was observed to be ∼ 2.2 V/μm and threshold field (corresponding to emission current density of 1 µA/cm2) was found to be 3.2 V/μm. The emission current was observed to be stable for more than three hours at a preset value 1 µA. The simple synthesis route and good field emission characteristics indicate potential of PANI nanofibres as a promising emitter for field emission based micro/nano devices.

  17. Effect of ceramic industrial particulate emission control on key components of ambient PM10.

    PubMed

    Minguillón, María Cruz; Monfort, Eliseo; Querol, Xavier; Alastuey, Andrés; Celades, Irina; Miró, José Vicente

    2009-06-01

    The relationship between specific particulate emission control and ambient levels of some PM(10) components (Zn, As, Pb, Cs, Tl) was evaluated. To this end, the industrial area of Castellón (Eastern Spain) was selected, where around 40% of the EU glazed ceramic tiles and a high proportion of EU ceramic frits are produced. The PM(10) emissions from the ceramic processes were calculated over the period 2000-2006, taking into account the degree of implementation of corrective measures throughout the study period. Abatement systems were implemented in the majority of the fusion kilns for frit manufacture in the area as a result of the application of the Directive 1996/61/EC, leading to a marked decrease in PM(10) emissions. By contrast, emissions from tile manufacture remained relatively constant because of the few changes in the implementation of corrective measures. On the other hand, ambient PM(10) levels and composition measurements were carried out from 2002 to 2006. A high correlation between PM(10) emissions from frit manufacture and ambient levels of Zn, As, Pb and Cs (R(2) from 0.61 to 0.98) was observed. On the basis of these results, the potential impact of the implementation of corrective measures to reduce emissions from tile manufacture was quantified, resulting in a possible decrease of 3-5 microg/m(3) and 2 microg/m(3) in ambient mineral PM(10) (on an annual basis) in urban and suburban areas, respectively. This relatively simple methodology allows us to estimate the direct effect of a reduction in primary particulate emissions on ambient levels of key particulate components, and to make a preliminary quantification of the possibilities of air quality improvement by means of further emission reduction. Therefore, it is a useful tool for developing future air quality plans in the study area and in other industrialised areas.

  18. Effects of Alternative Fuels and Aromatics on Gas-Turbine Particle Emissions

    NASA Astrophysics Data System (ADS)

    Thornhill, K. L., II; Moore, R.; Winstead, E.; Anderson, B. E.; Klettlinger, J. L.; Ross, R. C.; Surgenor, A.

    2015-12-01

    This presentation describes experiments conducted with a Honeywell GTCP36-150 Auxiliary Power Unit (APU) to evaluate the effects of varying fuel composition on particle emissions. The APU uses a single-stage compressor stage, gas turbine engine with a can-type combustor to generate bypass flow and electrical power for supporting small aircraft and helicopters. It is installed in a "hush-house" at NASA Glenn Research Center and is configured as a stand-alone unit that can be fueled from an onboard tank or external supply. It operates at constant RPM, but its fuel flow can be varied by changing the electrical load or volume of bypass flow. For these tests, an external bank of resistors were attached to the APU's DC and AC electrical outlets and emissions measurements were made at low, medium and maximum electrical current loads. Exhaust samples were drawn from several points downstream in the exhaust duct and fed to an extensive suite of gas and aerosol sensors installed within a mobile laboratory parked nearby. Aromatic- and sulfur-free synthetic kerosenes from Rentech, Gevo, UOP, Amyris and Sasol were tested and their potential to reduce PM emissions evaluated against a single Jet A1 base fuel. The role of aromatic compounds in regulating soot emissions was also evaluated by adding metered amounts of aromatic blends (Aro-100, AF-Blend, SAK) and pure compounds (tetracontane and 1-methylnaphthalene) to a base alternative fuel (Sasol). Results show that, relative to Jet A1, alternative fuels reduce nonvolatile particle number emissions by 50-80% and--by virtue of producing much smaller particles—mass emissions by 65-90%; fuels with the highest hydrogen content produced the greatest reductions. Nonvolatile particle emissions varied in proportion to fuel aromatic content, with additives containing the most complex ring structures producing the greatest emission enhancements.

  19. Effect of Dietary Protein on Ammonia Emission from Dairy Manure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this experiment was to investigate the effect of dietary crude protein concentration on ammonia (NH3) volatilization from dairy cow manure. Two types of manure were prepared by feeding lactating dairy cows diets with 16% (DM basis; HighCP) or 14% CP (LowCP). The manure was used in 2...

  20. Acid deposition in Asia: Emissions, deposition, and ecosystem effects

    NASA Astrophysics Data System (ADS)

    Duan, Lei; Yu, Qian; Zhang, Qiang; Wang, Zifa; Pan, Yuepeng; Larssen, Thorjørn; Tang, Jie; Mulder, Jan

    2016-12-01

    We review and synthesize the current state of knowledge regarding acid deposition and its environmental effects across Asia. The extent and magnitude of acid deposition in Asia became apparent only about one decade after this issue was well described in Europe and North America. In addition to the temperate zone, much of eastern and southern Asia is situated in the tropics and subtropics, climate zones hitherto little studied with respect to the effects of high loads of acid deposition. Surface waters across Asia are generally not sensitive to the effects of acid deposition, whereas soils in some regions are sensitive to acidification due to low mineral weathering. However, soil acidification was largely neutralized by such processes as base cation deposition, nitrate (NO3-) denitrification, and sulfate (SO42-) adsorption. Accompanying the decrease in S deposition in recent years, N deposition is of increasing concern in Asia. The acidifying effect of N deposition may be more important than S deposition in well drained tropical/subtropical soils due to high SO42- adsorption. The risk of regional soil acidification is a major threat in Eastern Asia, indicated by critical load exceedance in large areas.

  1. EFFECT OF SOOT AND COPPER COMBUSTOR DEPOSITS ON DIOXIN EMISSIONS

    EPA Science Inventory

    An experimental study was conducted to investigate the effects of residual soot and copper combustor deposits on the formation of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) during the combustion of a chlorinated waste. In a bench-scale set...

  2. Effect of surface roughness on the microwave emission from soils

    NASA Technical Reports Server (NTRS)

    Choudhury, B. J.; Schmugge, T. J.; Newton, R. W.; Chang, A. T. C.

    1978-01-01

    The effect of surface roughness on the brightness temperature of a moist terrain was studied through the modification of Fresnel reflection coefficient and using the radiative transfer equation. The modification involves introduction of a single parameter to characterize the roughness. It is shown that this parameter depends on both the surface height variance and the horizontal scale of the roughness. Model calculations are in good quantitative agreement with the observed dependence of the brightness temperature on the moisture content in the surface layer. Data from truck mounted and airborne radiometers are presented for comparison. The results indicate that the roughness effects are greatest for wet soils where the difference between smooth and rough surfaces can be as great as 50K.

  3. Effect of fuel injector type on performance and emissions of reverse-flow combustor

    NASA Technical Reports Server (NTRS)

    Norgren, C. T.; Riddlebaugh, S. M.

    1981-01-01

    The combustion process in a reverse-flow combustor suitable for a small gas turbine engine was investigated to evaluate the effect of fuel injector type on performance and emissions. Fuel injector configurations using pressure-atomizing, spill-flow, air blast, and air-assist techniques were compared and evaluated on the basis of performance obtained in a full-scale experimental combustor operated at inlet conditions corresponding to takeoff, cruise, low power, and idle and typical of a 16:1-pressure-ratio turbine engine. Major differences in combustor performance and emissions characteristics were experienced with each injector type even though the aerodynamic configuration was common to most combustor models. Performance characteristics obtained with the various fuel injector types could not have been predicted from bench-test injector spray characteristics. The effect of the number of operating fuel injectors on performance and emissions is also presented.

  4. Long-term changes in Jovian synchrotron radio emission - Intrinsic variations or effects of viewing geometry?

    NASA Astrophysics Data System (ADS)

    Hood, L. L.

    1993-04-01

    Possible causes of the observed long-term variation of Jovian synchrotron radio emission, including both intrinsic changes in the Jovian radiation belts and apparent changes due to variations in the Jovigraphic declination of the earth, DE, are investigated. An increase in diffusion rate with other parameters held constant results in an inward displacement of the peak emission radial distance that is not observed. Effects of viewing geometry changes are examined. The possible importance of such effects is suggested by a correlation between the total decimetric radio flux and DE, which varies between -3.3 and +3.3 deg during one Jovian orbital period. Because the Jovian central meridian longitudes where the magnetic latitude passes through zero during a given Jovian rotation change substantially with DE and since significant longitudinal asymmetries exist in both the volume emissivity and the latitudinal profile of the beam, the total intensity should be at least a partial function of D sub E.

  5. Effect of gallium environment on infrared emission in Er3+-doped gallium– antimony– sulfur glasses

    NASA Astrophysics Data System (ADS)

    Jiao, Qing; Li, Ge; Li, Lini; Lin, Changgui; Wang, Guoxiang; Liu, Zijun; Dai, Shixun; Xu, Tiefeng; Zhang, Qinyuan

    2017-01-01

    Gallium-based Ga–Sb–S sulfide glasses was elaborated and studied. A relationship between the structure, composition, and optical properties of the glass has been established. The effects of the introduction of Ga on the structure using infrared and Raman spectroscopies and on the Er3+-doped IR emission have been discussed. The results show that incorporation of Ga induced the dissociation of [SbS3] pyramids units and the formation of tetrahedral [GaS4] units. The dissolved rare earth ions are separated around the Ga–S bonding and the infrared emission quenching are controlled. Moreover, continuous introduction of Er ions into the glass forms more Er–S bonds through the further aggregation surrounding the [GaS4] units. In return, the infrared emission intensity decreased with excessive Er ion addition. This phenomenon is correlated with the recurrence concentration quenching effect induced by the increase of [GaS4] units.

  6. Comparison of Acute Health Effects From Exposures to Diesel and Biodiesel Fuel Emissions

    PubMed Central

    Mehus, Aaron A.; Reed, Rustin J.; Lee, Vivien S. T.; Littau, Sally R.; Hu, Chengcheng; Lutz, Eric A.

    2015-01-01

    Objective: To investigate the comparative acute health effects associated with exposures to diesel and 75% biodiesel/25% diesel (B75) blend fuel emissions. Methods: We analyzed multiple health endpoints in 48 healthy adults before and after exposures to diesel and B75 emissions in an underground mine setting—lung function, lung and systemic inflammation, novel biomarkers of exposure, and oxidative stress were assessed. Results: B75 reduced respirable diesel particulate matter by 20%. Lung function declined significantly more after exposure to diesel emissions. Lung inflammatory cells along with sputum and plasma inflammatory mediators increased significantly to similar levels with both exposures. Urinary 8-hydroxydeoxyguanosine, a marker of oxidative stress, was not significantly changed after either exposure. Conclusions: Use of B75 lowered respirable diesel particulate matter exposure and some associated acute health effects, although lung and systemic inflammation were not reduced compared with diesel use. PMID:26147538

  7. Effect of gallium environment on infrared emission in Er3+-doped gallium– antimony– sulfur glasses

    PubMed Central

    Jiao, Qing; Li, Ge; Li, Lini; Lin, Changgui; Wang, Guoxiang; Liu, Zijun; Dai, Shixun; Xu, Tiefeng; Zhang, Qinyuan

    2017-01-01

    Gallium-based Ga–Sb–S sulfide glasses was elaborated and studied. A relationship between the structure, composition, and optical properties of the glass has been established. The effects of the introduction of Ga on the structure using infrared and Raman spectroscopies and on the Er3+-doped IR emission have been discussed. The results show that incorporation of Ga induced the dissociation of [SbS3] pyramids units and the formation of tetrahedral [GaS4] units. The dissolved rare earth ions are separated around the Ga–S bonding and the infrared emission quenching are controlled. Moreover, continuous introduction of Er ions into the glass forms more Er–S bonds through the further aggregation surrounding the [GaS4] units. In return, the infrared emission intensity decreased with excessive Er ion addition. This phenomenon is correlated with the recurrence concentration quenching effect induced by the increase of [GaS4] units. PMID:28106143

  8. Effects of different forms of plant-derived organic matter on nitrous oxide emissions.

    PubMed

    Qiu, Qingyan; Wu, Lanfang; Ouyang, Zhu; Li, Binbin; Xu, Yanyan

    2016-07-13

    To investigate the impact of different forms of plant-derived organic matter on nitrous oxide (N2O) emissions, an incubation experiment with the same rate of total nitrogen (N) application was carried out at 25 °C for 250 days. Soils were incorporated with maize-derived organic matter (i.e., maize residue-derived dissolved organic matter and maize residues with different C/N ratios) and an inorganic N fertilizer (urea). The pattern and magnitude of nitrous oxide (N2O) emissions were affected by the form of N applied. Single application of maize-derived organic matter resulted in a higher N2O emission than single application of the inorganic N fertilizer or combined application of the inorganic N fertilizer and maize-derived organic matter. The positive effect of maize residue-derived dissolved organic matter (DOM) addition on N2O emissions was relatively short-lived and mainly occurred at the early stage following DOM addition. In contrast, the positive effect induced by maize residue addition was more pronounced and lasted for a longer period. Single application of maize residues resulted in a substantial decrease in soil nitric nitrogen (NO3(-)-N), but it did not affect the production of N2O. No significant relationship between N2O emission and NO3(-)-N and ammonium nitrogen (NH4(+)-N) suggested that the availability of soil N was not limiting the production of N2O in our study. The key factors affecting soil N2O emission were the soil dissolved organic carbon (DOC) content and metabolism quotient (qCO2). Both of them could explain 87% of the variation in cumulative N2O emission. The C/N ratio of maize-derived organic matter was a poor predictor of N2O emission when the soil was not limited by easily available C and the available N content met the microbial N demands for nitrification and denitrification. The results suggested that the magnitude of N2O emission was determined by the impact of organic amendments on soil C availability and microbial activity

  9. BVOC emission in Norway spruce: the effect of stand structure, high temperature and ozone levels.

    NASA Astrophysics Data System (ADS)

    Pallozzi, Emanuele; Guidolotti, Gabriele; Večeřová, Kristýna; Esposito, Raffaela; Lusini, Ilaria; Juráň, Stanislav; Urban, Otmar; Calfapietra, Carlo

    2015-04-01

    Norway spruce (Picea abies L.) is a widely distributed conifer species in the boreal zone and mountain areas of central Europe and is a moderate emitter of volatile organic compounds (BVOC). Although the vaporization and diffusion processes from resin ducts were generally considered to be the main processes for monoterpene emissions in conifers, recently it has been showed that a significant portion (up to one third) of monoterpene emissions of Norway spruce can originate from novel biosynthesis, thus depending on photosynthetic processes. For this reason, both biosynthesis and emission are strongly influenced by the environment and the stand structure. They increase with both increasing light and temperature during the warmer periods, although those are the periods with the higher ozone concentration that usually act as an inhibitor of both assimilation and isoprenoids synthesis and emission. On the other hand, stand structure can play an important role, because the photosynthetic capacity is influenced by temperature and light conditions through the canopy. In order to assess the effects of stand structure, temperature and ozone on isoprenoids emission of Norway spruce we carried out field and laboratory experiments. In the experimental field campaigns we measured: assimilation and BVOC emission from needles of sun and shade layers within the canopy of the spruce forest present at the Bily Kriz experimental research site (Moravian-Silesian Beskydy Mountains, 49° 33' N, 18° 32' E, NE of Czech Republic, 908 m a.s.l.). Moreover in the same layers we measured continuously concentration of BVOCs in the air using a PTR-TOF-MS. In laboratory we analyzed the effects of short-term exposure to high temperature and high ozone concentrations on branches of spruce trees collected at the Bily Kriz experimental research site. Preliminary results show that in Norway spruce both stand structure and environmental conditions influenced the gas exchange and BVOC emission rates

  10. [Effects of oxygenated fuels on emissions and carbon composition of fine particles from diesel engine].

    PubMed

    Shi, Xiao-Yan; He, Ke-Bin; Zhang, Jie; Ge, Yun-Shan; Tan, Jian-Wei

    2009-06-15

    Acetal (1,1-diethoxyethane) is considered as an alternative to ethanol as bio-derived additive for diesel fuel, which is miscible in diesel fuel. Biodiesel can improve the oxygen content and flash point of the fuel blend of acetal and diesel fuel. Two oxygenated fuels were prepared: a blend of 10% acetal + 90% diesel fuel and 10% acetal + 10% biodiesel + 80% diesel fuel. The emissions of NO(x), HC and PM2.5 from oxygenated fuels were investigated on a diesel engine bench at five modes according to various loads at two steady speeds and compared with base diesel fuel. Additionally, the carbon compositions of PM2.5 were analyzed by DRI thermal/optical carbon analyzer. Oxygenated fuels have unconspicuous effect on NO(x) emission rate but HC emission rate is observed significantly increased at some modes. The emission rate of PM2.5 is decreased by using oxygenated fuels and it decreases with the increase of fuel oxygen content. The emission rates of TC (total carbon) and EC (elemental carbon) in PM2.5 are also decreased by oxygenated fuels. The emission rate of organic carbon (OC) is greatly decreased at modes of higher engine speed. The OC/EC ratios of PM2.5 from oxygenated fuels are higher than that from base diesel fuel at most modes. The carbon compositions fractions of PM2.5 from the three test fuels are similar, and OC1 and EC1 are contributed to the most fractions of OC and EC, respectively. Compared with base diesel fuel, oxygenated fuels decrease emission rate of PM2.5, and have more OC contribution to PM2.5 but have little effect on carbon composition fractions.

  11. 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.

  12. Inhalation of motor vehicle emissions: effects of urban population and land area

    NASA Astrophysics Data System (ADS)

    Marshall, Julian D.; McKone, Thomas E.; Deakin, Elizabeth; Nazaroff, William W.

    2005-01-01

    Urban population density may influence transportation demand, e.g., as expressed through average daily vehicle-kilometers traveled in private motor vehicles per capita. In turn, changes in transportation demand influence total passenger vehicle emissions to which populations are exposed. Population density can also influence the fraction of total emissions that are inhaled by the exposed urban population. Equations are presented that describe these relationships for an idealized representation of an urban area. Using analytic solutions to these equations, we investigate the effect of three changes in urban population and urban land area (infill, sprawl, and constant-density growth) on per capita inhalation intake of primary pollutants from passenger vehicles. For the system considered, the magnitude of these effects depends on density-emissions elasticity (εe) , a normalized derivative relating change in population density to change in vehicle emissions. For example, based on the idealized representation of the emissions-to-intake relationship presented herein, if urban population increases, then per capita intake is less with infill development than with constant-density growth if εe is <-0.5, while for εe >-0.5, the reverse is true.

  13. The effect of biofuel production on swine farm methane and ammonia emissions.

    PubMed

    Harper, Lowry A; Flesch, Thomas K; Weaver, Kim H; Wilson, John D

    2010-01-01

    Methane (CH) and ammonia (NH3) are emitted to the atmosphere during anaerobic processing of organic matter, and both gases have detrimental environmental effects. Methane conversion to biofuel production has been suggested to reduce CH4 emissions from animal manure processing systems. The purpose of this research is to evaluate the change in CH4 and NH3 emissions in an animal feeding operation due to biofuel production from the animal manure. Gas emissions were measured from swine farms differing only in their manure-management treatment systems (conventional vs. biofuel). By removing organic matter (i.e., carbon) from the biofuel farms' manure-processing lagoons, average annual CH4 emissions were decreased by 47% compared with the conventional farm. This represents a net 44% decrease in global warming potential (CO2 equivalent) by gases emitted from the biofuel farms compared with conventional farms. However, because of the reduction of methanogenesis and its reduced effect on the chemical conversion of ammonium (NH4+) to dinitrogen (N2) gas, NH3 emissions in the biofuel farms increased by 46% over the conventional farms. These studies show that what is considered an environmentally friendly technology had mixed results and that all components of a system should be studied when making changes to existing systems.

  14. The effect of ethanol blended diesel fuels on emissions from a diesel engine

    NASA Astrophysics Data System (ADS)

    He, Bang-Quan; Shuai, Shi-Jin; Wang, Jian-Xin; He, Hong

    The addition of ethanol to diesel fuel simultaneously decreases cetane number, high heating value, aromatics fractions and kinematic viscosity of ethanol blended diesel fuels and changes distillation temperatures. An additive used to keep the blends homogenous and stable, and an ignition improver, which can enhance cetane number of the blends, have favorable effects on the physicochemical properties related to ignition and combustion of the blends with 10% and 30% ethanol by volume. The emission characteristics of five fuels were conducted on a diesel engine. At high loads, the blends reduce smoke significantly with a small penalty on CO, acetaldehyde and unburned ethanol emissions compared to diesel fuel. NO x and CO 2 emissions of the blends are decreased somewhat. At low loads, the blends have slight effects on smoke reduction due to overall leaner mixture. With the aid of additive and ignition improver, CO, unburned ethanol and acetaldehyde emissions of the blends can be decreased moderately, even total hydrocarbon emissions are less than those of diesel fuel. The results indicate the potential of diesel reformation for clean combustion in diesel engines.

  15. Effects of phosphogypsum and superphosphate on compost maturity and gaseous emissions during kitchen waste composting.

    PubMed

    Yang, Fan; Li, Guoxue; Shi, Hong; Wang, Yiming

    2015-02-01

    This study investigated the effects of phosphogypsum and superphosphate on the maturity and gaseous emissions of composting kitchen waste. Two amended compost treatments were conducted using phosphogypsum and superphosphate as additives with the addition of 10% of initial raw materials (dry weight). A control treatment was also studied. The treatments were conducted under aerobic conditions in 60-L reactors for 35 days. Maturity indexes were determined, and continuous measurements of CH4, N2O, and NH3 were taken. Phosphogypsum and superphosphate had no negative effects on compost maturity, although superphosphate inhibited the temperature rise in the first few days. The addition of phosphogypsum and superphosphate drastically reduced CH4 emissions (by 85.8% and 80.5%, respectively) and decreased NH3 emissions (by 23.5% and 18.9%, respectively). However, a slight increase in N2O emissions (by 3.2% and 14.8%, respectively) was observed. Composting with phosphogypsum and superphosphate reduced total greenhouse gas emissions by 17.4% and 7.3% respectively.

  16. A review of the global emissions, transport and effects of heavy metals in the environment

    SciTech Connect

    Friedman, J.R.; Ashton, W.B.; Rapoport, R.D.

    1993-06-01

    The purpose of this report is to describe the current state of knowledge regarding the sources and quantities of heavy metal emissions, their transport and fate, their potential health and environmental effects, and strategies to control them. The approach is to review the literature on this topic and to consult with experts in the field. Ongoing research activities and research needs are discussed. Estimates of global anthropogenic and natural emissions indicate that anthropogenic emissions are responsible for most of the heavy metals released into the atmosphere and that industrial activities have had a significant impact on the global cycling of trace metals. The largest anthropogenic sources of trace metals are coal combustion and the nonferrous metal industry. Atmospheric deposition is an important pathway by which trace metals enter the environment. Atmospheric deposition varies according to the solubility of the element and the length of time it resides in the atmosphere. Evidence suggests that deposition is influenced by other chemicals in the atmosphere, such as ozone and sulfur dioxide. Trace metals also enter the environment through leaching. Existing emissions-control technologies such as electrostatic precipitators, baghouses, and scrubbers are designed to remove other particulates from the flue gas of coal-fired power plants and are only partially effective at removing heavy metals. Emerging technologies such as flue gas desulfurization, lignite coke, and fluidized bed combustion could further reduce emissions. 108 refs.

  17. Water loss control using pressure management: life-cycle energy and air emission effects.

    PubMed

    Stokes, Jennifer R; Horvath, Arpad; Sturm, Reinhard

    2013-10-01

    Pressure management is one cost-effective and efficient strategy for controlling water distribution losses. This paper evaluates the life-cycle energy use and emissions for pressure management zones in Philadelphia, Pennsylvania, and Halifax, Nova Scotia. It compares water savings using fixed-outlet and flow-modulated pressure control to performance without pressure control, considering the embedded electricity and chemical consumption in the lost water, manufacture of pipe and fittings to repair breaks caused by excess pressure, and pressure management. The resulting energy and emissions savings are significant. The Philadelphia and Halifax utilities both avoid approximately 130 million liters in water losses annually using flow-modulated pressure management. The conserved energy was 780 GJ and 1900 GJ while avoided greenhouse gas emissions were 50 Mg and 170 Mg a year by Philadelphia and Halifax, respectively. The life-cycle financial and environmental performance of pressure management systems compares favorably to the traditional demand management strategy of installing low-flow toilets. The energy savings may also translate to cost-effective greenhouse gas emission reductions depending on the energy mix used, an important advantage in areas where water and energy are constrained and/or expensive and greenhouse gas emissions are regulated as in California, for example.

  18. Effect of tillage and water management on GHG emissions from Mediterranean rice growing ecosystems

    NASA Astrophysics Data System (ADS)

    Fangueiro, David; Becerra, Daniel; Albarrán, Ángel; Peña, David; Sanchez-Llerena, Javier; Rato-Nunes, José Manuel; López-Piñeiro, Antonio

    2017-02-01

    Paddy rice fields are an important source of greenhouse gases (GHG), especially methane. In the present work, we assessed the impact on GHG emissions of two main parameters of rice production: aerobic rice production was compared with traditional flooded rice production and conventional tillage (CT) was compared with short-term and long-term no-tillage (NT) management. A field experiment was performed over three years and the GHG emissions were measured during each year. Five treatments (3 replicates) were considered: NTS7: no-tillage over seven years and sprinkler irrigation; NTS: no-tillage and sprinkler irrigation; CTS: conventional tillage and sprinkler irrigation; NTF: no-tillage and flooding; CTF: conventional tillage and flooding. The use of sprinkler irrigation rather than flooding led to decreases in nitrous oxide and methane emissions of ∼40% and more than 99%, respectively, over the 3-year experiment. The use of sprinkler irrigation compared with flooded irrigation reduced the global warming potential (GWP) about 40% and 36% in no-tillage and conventional tillage treatments, respectively. Treatment NTF decreased CH4 emissions, relative to CTF, by ∼60% over three years but the effect of NT on N2O emissions was not clear: a decrease or no effect was mostly observed in the NT treatments, relative to CT. A decrease of ∼40% in the total GHG emissions was observed in the NT treatments, relative to CT. No or small differences between NTS and NTS7 in terms of gaseous emissions were found. The short-term no-tillage and sprinkler irrigated treatment (NTS) gave lower yields than CTF in 2011 and 2012, but reached similar yields in the third year (NTS 8229 kg ha-1;CTF 8926 kg ha-1), with average savings of 75% of the total amount of water applied in CTF. The NTS7 data showed that high yields (reaching 9805 kg ha-1 in 2012) and water savings are sustainable in the long term. Considering the yield-scaled GWP of the emissions, NT gave a decrease of up to 42

  19. Experimental research on the effects of water application on greenhouse gas emissions from beef cattle feedlots

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of water application (e.g., through rainfall or sprinkler system) on emissions of greenhouse gases (GHGs), such as nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2), from pen surfaces of open-lot beef cattle feedlots was evaluated under controlled laboratory conditions. Soil/ma...

  20. Effect of Dietary Forage to Concentrate Ratio on Lactation Performance and Methane Emission from Dairy Cows

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our objective was to determine the effect of feeding diets with different forage to concentrate ratios (F:C) on performance and methane (CH4) emission from lactating dairy cows. Eight multiparous Holstein cows (means ± standard deviation: 620 ± 38 kg of body weight (BW); 41 ± 34 days in milk (DIM)) ...

  1. Nitrogen Source Effects on Soil Nitrous Oxide Emissions from No-Till Corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of N fertilizer source on soil nitrous oxide (N2O) emissions from a no-till, irrigated continuous corn field was evaluated near Fort Collins, CO in 2009 and 2010. Five N sources (urea, ESN, SuperU, UAN, UAN+AgrotainPlus) were surface band applied at 202 kg N/ha at corn emergence, includi...

  2. Nitrogen Source Effects on Nitrous Oxide Emissions from a Strip-Tilled Corn Field

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effects of N source on nitrous oxide (N2O) emissions from a strip-till, irrigated continuous corn field was evaluated near Fort Collins, CO. Six N fertilizer sources (urea, ESN, SuperU, UAN, UAN+AgrotainPlus, UAN+Nfusion) were surface band applied at 202 kg N/ha near the corn row at corn emerge...

  3. EFFECTS OF BURN RATE, WOOD SPECIES, MOISTURE CONTENT AND WEIGHT OF WOOD LOADED ON WOODSTOVE EMISSIONS

    EPA Science Inventory

    The report gives results of tests of four woodstove operating parameters (burn rate, wood moisture, wood load, and wood species) at two levels each using a half factorial experimental test design to determine statistically significant effects on the emission components CO, CO2, p...

  4. Nitrogen placement effects on soil nitrous oxide emissions from irrigated corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Limited information is available on how N fertilizer placement affects soil nitrous oxide (N2O) emissions under irrigated conditions in the semi-arid western U.S. Our objective was to evaluate the effects of surface banding (applied near corn row) and broadcasting of three N sources (urea, polymer...

  5. Nitrogen Placement Effects on Soil Nitrous Oxide Emissions from Irrigated Corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Limited information is available on how N fertilizer placement affects soil nitrous oxide emissions under irrigated conditions in the semi-arid western U.S. Our objective was to evaluate the effects of surface banding (applied near corn row) and broadcasting of three N sources (urea, polymer-coated ...

  6. Assessing the effectiveness of vegetative environmental buffers in mitigating air pollutant emissions from poultry houses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Over 560 million broilers are produced on the Delmarva Peninsula each year. However, emissions from poultry houses have come under intense scrutiny due to the potential human and environmental effects of the released particulate matter (PM), ammonia, and volatile organic compounds (VOCs). Ammonia an...

  7. A review of the global emissions, transport, and effects of heavy metals in the environment

    SciTech Connect

    Friedman, J.R.; Ashton, W.B.; Rapoport, R.D.

    1993-05-01

    The purpose of this report is to describe the current state of knowledge regarding the sources and quantities of heavy metal emissions, their transport and fate, their potential health and environmental effects, and strategies to control them. The approach is to review the literature on this topic and to consult with experts in the field. Ongoing research activities and research needs are discussed.

  8. Effects of anaerobic digestion and aerobic treatment on gaseous emissions from dairy manure storages

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effects of anaerobic digestion and aerobic treatment on the reduction of gaseous emissions from dairy manure storages were evaluated in this study. Screened dairy manure containing 3.5% volatile solids (VS) was either anaerobically digested or aerobically treated prior to storage in air-tight vessel...

  9. EFFECTS OF APPLIANCE TYPE AND OPERATING VARIABLES ON WOODSTOVE EMISSIONS: VOLUME II. APPENDICIES D-F.

    EPA Science Inventory

    The report gives results of a project, in support of the intergared Air Cancer Project (IACP), to provide data on the specific effects of appliance type and operating variables on woodstove emissions. samples of particulate material and volatile organic compounds (VOCs) were coll...

  10. The "APEC Blue" phenomenon: Regional emission control effects observed from space

    NASA Astrophysics Data System (ADS)

    Huang, Kan; Zhang, Xingying; Lin, Yanfen

    2015-10-01

    Observations from space were used to evaluate the effect of emission control measures on the changes of air pollutants in Beijing and its surroundings during the 2014 Asia-Pacific Economic Cooperation (APEC) Summit held in Beijing. Compared to the past three years (2011-2013), NO2 tropospheric vertical column densities in 2014 were found to exhibit almost across-the-board significant reductions over the North China Plain, suggesting the effectiveness of the national policy on NOx emission reduction during China's 12th "Five-Year-Plan". During the APEC period (Nov. 3-11), AOD and AAOD were found reduced the most in Beijing, followed by Hebei province. Stringent emission control measures implemented in Beijing and the regional joint control over the surroundings especially in Hebei were responsible for the good air quality and so-called "APEC Blue". However, air quality plummeted during the post-APEC period (Nov. 12-30), which was largely related to the lifting of local and regional joint emission control measures. By applying a spatial correlation analysis method, the potential emission source regions impacting air quality of Beijing included widespread areas in Hebei, Shandong, Shanxi, and Tianjin in the past three years (2011-2013). While during the study period in 2014, areas impacting Beijing evidently shrank and were limited within Hebei, suggesting evident effects of intense emission perturbations on lowering the extent of regional transport. This study indicates short-term measures did fix the air pollution problems in China but a permanent solution is still a tremendous challenge.

  11. Effectiveness of emission control technologies for auxiliary engines on ocean-going vessels.

    PubMed

    Jayaram, Varalakshmi; Nigam, Abhilash; Welch, William A; Miller, J Wayne; Cocker, David R

    2011-01-01

    Large auxiliary engines operated on ocean-going vessels in transit and at berth impact the air quality of populated areas near ports. This paper presents new information on the comparison of emission ranges from three similar engines and the effectiveness of three control technologies: switching to cleaner burning fuels, operating in the low oxides of nitrogen (NOx) mode, and selective catalytic reduction (SCR). In-use measurements of gaseous (NOx, carbon monoxide [CO], carbon dioxide [CO2]) and fine particulate matter (PM2.5; total and speciated) emissions were made on three auxiliary engines on post-PanaMax class container vessels following the International Organization for Standardization-8178-1 protocol. The in-use NOx emissions for the MAN B&W 7L32/40 engine family vary from 15 to 21.1 g/kW-hr for heavy fuel oil and 8.9 to 19.6 g/kW-hr for marine distillate oil. Use of cleaner burning fuels resulted in NOx reductions ranging from 7 to 41% across different engines and a PM2.5 reduction of up to 83%. The NOx reductions are a consequence of fuel nitrogen content and engine operation; the PM2.5 reduction is attributed to the large reductions in the hydrated sulfate and organic carbon (OC) fractions. As expected, operating in the low-NOx mode reduced NOx emissions by approximately 32% and nearly doubled elemental carbon (EC) emissions. However, PM2.5 emission factors were nearly unchanged because the EC emission factor is only approximately 5% of the total PM2.5 mass. SCR reduced the NOx emission factor to less than 2.4 g/kW-hr, but it increased the PM2.5 emissions by a factor of 1.5-3.8. This increase was a direct consequence of the conversion of sulfur dioxide to sulfate emissions on the SCR catalyst. The EC and OC fractions of PM2.5 reduced across the SCR unit.

  12. Effects of N and C Distribution on N-Emissions during Denitrification

    NASA Astrophysics Data System (ADS)

    Loick, Nadine; Dixon, Liz; Abalos, Diego; Vallejo, Antonio; Watson, Catherine; McGeough, Karen; Matthews, Peter; Cardenas, Laura

    2015-04-01

    Agricultural soils are a major source of nitric- (NO) and nitrous oxide (N2O) which are produced and consumed by biotic and abiotic soil processes. The dominant sources of NO and N2O are microbial nitrification and denitrification. Which process dominates depends on environmental conditions such as pH and water filled pore space (WFPS) as well as substrate availability which is seldom homogeneous across the whole field. N2O emissions have been attributed to both processes whereas NO emissions are thought to predominantly derive from nitrification. Recent findings challenge the latter assumption indicating denitrification to be a significant source of NO. The present study investigated the impact that N and C application hot spots have on emissions of NO and N2O as well as the significance of denitrification as a source of NO emissions. This study used the gas-flow-soil-core technique (Cardenas et al 2003) to simultaneously measure three nitrogen-gases (NO, N2O, N2) and CO2. This was combined with 15N labelled isotopic techniques to determine the source of N-emissions. A nutrient solution containing KNO3 with 15N at 5 atom% and glucose was applied at a rate of 75 kg N ha-1 and 400 kg C ha-1 to vessels containing three repacked grassland soil cores, where the amendment was either split and applied equally to the three cores or the full rate was applied to only one of the cores, mimicking heterogeneous fertiliser application. Under field conditions nutrient/fertiliser application is seldom homogeneous across the whole field and our results show a clear effect of the heterogeneous application of nutrients. NO emissions were significantly lower when a high concentration of nutrients was applied to a single core compared to an even distribution over multiple cores. Total emissions of N2O, N2 and CO2, however, were not affected by application heterogeneity but showed a delay in the occurrence of the peak of all three gases when the nutrients were applied to only one core

  13. The effect of agency budgets on minimizing greenhouse gas emissions from road rehabilitation policies

    NASA Astrophysics Data System (ADS)

    Reger, Darren; Madanat, Samer; Horvath, Arpad

    2015-11-01

    Transportation agencies are being urged to reduce their greenhouse gas (GHG) emissions. One possible solution within their scope is to alter their pavement management system to include environmental impacts. Managing pavement assets is important because poor road conditions lead to increased fuel consumption of vehicles. Rehabilitation activities improve pavement condition, but require materials and construction equipment, which produce GHG emissions as well. The agency’s role is to decide when to rehabilitate the road segments in the network. In previous work, we sought to minimize total societal costs (user and agency costs combined) subject to an emissions constraint for a road network, and demonstrated that there exists a range of potentially optimal solutions (a Pareto frontier) with tradeoffs between costs and GHG emissions. However, we did not account for the case where the available financial budget to the agency is binding. This letter considers an agency whose main goal is to reduce its carbon footprint while operating under a constrained financial budget. A Lagrangian dual solution methodology is applied, which selects the optimal timing and optimal action from a set of alternatives for each segment. This formulation quantifies GHG emission savings per additional dollar of agency budget spent, which can be used in a cap-and-trade system or to make budget decisions. We discuss the importance of communication between agencies and their legislature that sets the financial budgets to implement sustainable policies. We show that for a case study of Californian roads, it is optimal to apply frequent, thin overlays as opposed to the less frequent, thick overlays recommended in the literature if the objective is to minimize GHG emissions. A promising new technology, warm-mix asphalt, will have a negligible effect on reducing GHG emissions for road resurfacing under constrained budgets.

  14. Effects of different mixing ratios on emissions from passenger cars fueled with methanol/gasoline blends.

    PubMed

    Zhao, Hong; Ge, Yunshan; Tan, Jianwei; Yin, Hang; Guo, Jiadong; Zhao, Wei; Dai, Peipei

    2011-01-01

    Regulated and unregulated emissions from four passenger cars fueled with methanol/gasoline blends at different mixing ratios (M15, M20, M30, M50, M85 and M100) were tested over the New European Driving Cycle (NEDC). Volatile organic compounds (VOCs) were sampled by Tenax TA and analyzed by thermal desorption-gas chromatograph/mass spectrometer (TD-GC/MS). Carbonyls were trapped on dinitrophenylhydrazine (DNPH) cartridges and analyzed by high performance liquid chromatography (HPLC). The results showed that total emissions of VOCs and BTEX (benzene, toluene, ethylbenzene, p, m, o-xylene) from all vehicles fueled with methanol/gasoline blends were lower than those from vehicles fueled with only gasoline. Compared to the baseline, the use of M85 decreased BTEX emissions by 97.4%, while the use of M15 decreased it by 19.7%. At low-to-middle mixing ratios (M15, M20, M30 and M50), formaldehyde emissions showed a slight increase while those of high mixing ratios (M85 and M100) were three times compared with the baseline gasoline only. When the vehicles were retrofitted with new three-way catalytic converters (TWC), emissions of carbon monoxide (CO), total hydrocarbon (THC), and nitrogen oxides (NO(x)) were decreased by 24%-50%, 10%-35%, and 24%-58% respectively, compared with the cars using the original equipment manufacture (OEM) TWC. Using the new TWC, emissions of formaldehyde and BTEX were decreased, while those of other carbonyl increased. It is necessary that vehicles fueled with methanol/gasoline blends be retrofitted with a new TWC. In addition, the specific reactivity of emissions of vehicles fueled with M15 and retrofitted with the new TWC was reduced from 4.51 to 4.08 compared to the baseline vehicle. This indicates that the use of methanol/gasoline blend at a low mixing ratio may have lower effect on environment than gasoline.

  15. Effects of organic nitrification inhibitors on methane and nitrous oxide emission from tropical rice paddy

    NASA Astrophysics Data System (ADS)

    Datta, A.; Adhya, T. K.

    2014-08-01

    We have studied the effects of application of different nitrification inhibitors on methane (CH4) and nitrous oxide (N2O) emissions from rice paddy and associated soil chemical and biological dynamics during wet and dry seasons of rice crop in a tropical climate of eastern India. The experiment consisted of four treatments viz. (i) Prilled urea amended control (ii) urea + Dicyandiamide (DCD), (iii) urea + Nimin and (iv) urea + Karanjin. CH4 emission was significantly higher from the DCD (372.36 kg ha-1) and Karanjin (153.07 kg ha-1) applied plots during the wet and dry season, respectively. N2O emission was significantly inhibited in the Nimin applied plots during both seasons (69% and 85% over control during wet season and dry season respectively). CH4 and N2O emissions per Mg of rice grain yield were lowest from the Nimin applied plots during both seasons. Global warming potential (GWP) of the plot treated with DCD (13.93) was significantly higher during the experimental period. CH4 production potential was significantly higher from the nitrification inhibitor applied plots compared to control. While, CH4 oxidation potential followed the order; urea + Nimin > urea + Karanjin > urea + DCD > control. Application of Nimin significantly increased the methanotrophic bacterial population in the soil during the maximum tillering to flowering stage and may be attributed to low CH4 emission from the plots. Denitrification enzyme activity (DEA) of the soil was significantly low from the Nimin and Karanjin applied plots. Results suggest that apart from being potent nitrification inhibitors, Nimin and Karanjin also have the potential to reduce the denitrification activity in the soil. This in turn, would reduce N2O emission from flooded paddy where both nitrification and denitrification processes causes N2O emission.

  16. The Effect of Spray Initial Conditions on Heat Release and Emissions in LDI CFD Calculations

    NASA Technical Reports Server (NTRS)

    Iannetti, Anthony C.; Liu, Nan-Suey; Davoudzadeh, Farhad

    2008-01-01

    The mass and velocity distribution of liquid spray has a primary effect on the combustion heat release process. This heat release process then affects emissions like nitrogen oxides (NOx) and carbon monoxide (CO). Computational Fluid Dynamics gives the engineer insight into these processes, but various setup options exist (number of droplet groups, and initial droplet temperature) for spray initial conditions. This paper studies these spray initial condition options using the National Combustion Code (NCC) on a single swirler lean direct injection (LDI) flame tube. Using laminar finite rate chemistry, comparisons are made against experimental data for velocity measurements, temperature, and emissions (NOx, CO).

  17. Measuring the Effect of Fuel Chemical Structure on Particulate and Gaseous Emissions using Isotope Tracing

    SciTech Connect

    Buchholz, B A; Mueller, C J; Martin, G C; Upatnicks, A; Dibble, R W; Cheng, S

    2003-09-11

    Using accelerator mass spectrometry (AMS), a technique initially developed for radiocarbon dating and recently applied to internal combustion engines, carbon atoms within specific fuel molecules can be labeled and followed in particulate or gaseous emissions. In addition to examining the effect of fuel chemical structure on emissions, the specific source of carbon for PM can be identified if an isotope label exists in the appropriate fuel source. Existing work has focused on diesel engines, but the samples (soot collected on quartz filters or combustion gases captured in bombs or bags) are readily collected from large industrial combustors as well.

  18. Effect of metal and dielectric environments on emission kinetics of HITC dye (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Prayakarao, Srujana; Bonner, Carl E.; Noginov, Mikhail A.

    2016-09-01

    We study the influence of metallic and dielectric films as well as lamellar multilayered stacks on the emission kinetics of Poly(methyl methacrylate) (PMMA) polymer doped with HITC dye at various concentrations. The two factors affecting the emission kinetics are the Purcell enhancement and self-quenching, which is particularly strong at high dye concentrations. Both effects are modified in different ways in the vicinity of metal/dielectric substrates) and appear to interfere with each other. The detailed account of the experimental results and analysis will be presented at the conference.

  19. Effects of aerosol emission pathways on future warming and human health

    NASA Astrophysics Data System (ADS)

    Partanen, Antti-Ilari; Matthews, Damon

    2016-04-01

    The peak global temperature is largely determined by cumulative emissions of long-lived greenhouse gases. However, anthropogenic emissions include also so-called short-lived climate forcers (SLCFs), which include aerosol particles and methane. Previous studies with simple models indicate that the timing of SLCF emission reductions has only a small effect on the rate of global warming and even less of an effect on global peak temperatures. However, these simple model analyses do not capture the spatial dynamics of aerosol-climate interactions, nor do they consider the additional effects of aerosol emissions on human health. There is therefore merit in assessing how the timing of aerosol emission reductions affects global temperature and premature mortality caused by elevated aerosol concentrations, using more comprehensive climate models. Here, we used an aerosol-climate model ECHAM-HAMMOZ to simulate the direct and indirect radiative forcing resulting from aerosol emissions. We simulated Representative Concentration Pathway (RCP) scenarios, and we also designed idealized low and high aerosol emission pathways based on RCP4.5 scenario (LOW and HIGH, respectively). From these simulations, we calculated the Effective Radiative Forcing (ERF) from aerosol emissions between 1850 and 2100, as well as aerosol concentrations used to estimate the premature mortality caused by particulate pollution. We then use the University of Victoria Earth System Climate Model to simulate the spatial and temporal pattern of climate response to these aerosol-forcing scenarios, in combination with prescribed emissions of both short and long-lived greenhouse gases according to the RCP4.5 scenario. In the RCP scenarios, global mean ERF declined during the 21st century from -1.3 W m-2 to -0.4 W m-2 (RCP8.5) and -0.2 W m-2 (RCP2.6). In the sensitivity scenarios, the forcing at the end of the 21st century was -1.6 W m-2 (HIGH) and practically zero (LOW). The difference in global mean temperature

  20. Nitrogen, tillage, and crop rotation effects on nitrous oxide emissions from irrigated cropping systems.

    PubMed

    Halvorson, Ardell D; Del Grosso, Stephen J; Reule, Curtis A

    2008-01-01

    We evaluated the effects of irrigated crop management practices on nitrous oxide (N(2)O) emissions from soil. Emissions were monitored from several irrigated cropping systems receiving N fertilizer rates ranging from 0 to 246 kg N ha(-1) during the 2005 and 2006 growing seasons. Cropping systems included conventional-till (CT) continuous corn (Zea mays L.), no-till (NT) continuous corn, NT corn-dry bean (Phaseolus vulgaris L.) (NT-CDb), and NT corn-barley (Hordeum distichon L.) (NT-CB). In 2005, half the N was subsurface band applied as urea-ammonium nitrate (UAN) at planting to all corn plots, with the rest of the N applied surface broadcast as a polymer-coated urea (PCU) in mid-June. The entire N rate was applied as UAN at barley and dry bean planting in the NT-CB and NT-CDb plots in 2005. All plots were in corn in 2006, with PCU being applied at half the N rate at corn emergence and a second N application as dry urea in mid-June followed by irrigation, both banded on the soil surface in the corn row. Nitrous oxide fluxes were measured during the growing season using static, vented chambers (1-3 times wk(-1)) and a gas chromatograph analyzer. Linear increases in N(2)O emissions were observed with increasing N-fertilizer rate, but emission amounts varied with growing season. Growing season N(2)O emissions were greater from the NT-CDb system during the corn phase of the rotation than from the other cropping systems. Crop rotation and N rate had more effect than tillage system on N(2)O emissions. Nitrous oxide emissions from N application ranged from 0.30 to 0.75% of N applied. Spikes in N(2)O emissions after N fertilizer application were greater with UAN and urea than with PCU fertilizer. The PCU showed potential for reducing N(2)O emissions from irrigated cropping systems.

  1. A comparison of estimates of cost-effectiveness of alternative fuels and vehicles for reducing emissions

    SciTech Connect

    Hadder, G.R.

    1995-11-01

    The cost-effectiveness ratio (CER) is a measure of the monetary value of resources expended to obtain reductions in emissions of air pollutants. The CER can lead to selection of the most effective sequence of pollution reduction options. Derived with different methodologies and technical assumptions, CER estimates for alternative fuel vehicles (AFVs) have varied widely among pervious studies. In one of several explanations of LCER differences, this report uses a consistent basis for fuel price to re-estimate CERs for AFVs in reduction of emissions of criteria pollutants, toxics, and greenhouse gases. The re-estimated CERs for a given fuel type have considerable differences due to non-fuel costs and emissions reductions, but the CERs do provide an ordinal sense of cost-effectiveness. The category with CER less than $5,000 per ton includes compressed natural gas and ed Petroleum gas vehicles; and E85 flexible-fueled vehicles (with fuel mixture of 85 percent cellulose-derived ethanol in gasoline). The E85 system would be much less attractive if corn-derived ethanol were used. The CER for E85 (corn-derived) is higher with higher values placed on the reduction of gas emissions. CER estimates are relative to conventional vehicles fueled with Phase 1 California reformulated gasoline (RFG). The California Phase 2 RFG program will be implemented before significant market penetration by AFVs. CERs could be substantially greater if they are calculated incremental to the Phase 2 RFG program. Regression analysis suggests that different assumptions across studies can sometimes have predictable effects on the CER estimate of a particular AFV type. The relative differences in cost and emissions reduction assumptions can be large, and the effect of these differences on the CER estimate is often not predictable. Decomposition of CERs suggests that methodological differences can make large contributions to CER differences among studies.

  2. Effect of anodization voltage on electron field emission from carbon nanotubes in anodized alumina template.

    PubMed

    Wisitsoraat, A; Phokharatkul, D; Komin, K; Jaruwongrangsee, K; Tuantranont, A

    2011-12-01

    In this work, electron field emission from AAO-CNT structure is studied as a function of anodizing voltage. It is found that the turn-on electric field of AAO-CNTs reduces from 5 V/microm to 4 V/microm as anodization voltage increase from 20 to 30 V. On the other hand, CNTs the turn-on electric field of AAO-CNTs increases from 4 V/microm to 6 V/microm as anodization voltage increase from 30 to 40 V. Thus, anodization voltage of 30 V provides an optimal AAO-CNTs structure for electron field emission. The emission data have been analyzed based on the Fowler Nordhiem (F-N) model. AAO template prepared with 30 V anodization voltage is found to yield CNT nanoarray with optimum alignment and spacing that increase field enhancement factor by the lowering of field screening effect without significant lowering of CNTs density.

  3. Surface Roughness Effect on Secondary Electron Emission from Beryllium under Electron Bombardment

    NASA Astrophysics Data System (ADS)

    Kawata, Jun; Ohya, Kaoru

    1994-02-01

    A direct Monte Carlo model is developed to simulate secondary electron emission from beryllium with a flat surface and Gaussian-ripple surfaces. The calculated electron yield and energy distribution of secondary electrons are in reasonable agreement with the experimental data. The emphasis is in this study put on the effect of surface roughness on secondary electron emission. The number of secondary electrons emitted largely depends on the position of bombardment of primary electrons on the ripple surface. The energy distribution of secondary electrons emitted from the ripple surface shifts towards low-energy side in comparison with the distribution for the flat surface. The over-cosine and gourd-shaped angular distributions, depending on the position of bombardment, are calculated for emission angle of electrons from the ripple surface; the distribution for the flat surface agrees quite well with the cosine distribution.

  4. [Effects of transmission counts on image quality during simultaneous emission/transmission scan].

    PubMed

    Inoue, Kazumasa; Oda, Keiichi; Fukushi, Masahiro

    2006-06-20

    We compared the pre-injection transmission scan with the simultaneous emission/transmission scan (SET) using a body phantom in positron emission tomography (PET) to study the factors affecting emission (EMIS) images with different transmission (TRAN) data. The results showed that total count, region, scan method, and EMIS component influenced the bias and noise statistics. This influence was further passed on to the EMIS data and affected the reconstructed image. However, the result of fixing EMIS scan time at 10 minutes was that the noise statistics of EMIS had a greater effect on image quality than TRAN. The optimal scan counts of SET in this study were 20 Mcounts, with a scan time of about 10 minutes (85.5 MBq, (68)Ge-(68)Ga radioactivity). In clinical use, optimal collection count differs, as radiation TRAN quantity depends on the size of the subject, even with fixed radioactivity of (68)Ge-(68)Ga.

  5. The effect of impurities and incident angle on the secondary electron emission of Ni(110)

    NASA Astrophysics Data System (ADS)

    Lazar, Hadar; Patino, Marlene; Raitses, Yevgeny; Koel, Bruce E.; Gentile, Charles; Feibush, Eliot

    2015-11-01

    The investigation of secondary electron emission (SEE) of conducting materials used for magnetic fusion devices and plasma thrusters is important for determining device lifetime and performance. Methods to quantify the secondary electron emission from conducting materials and to characterize the effects that impurities and incident angles have on secondary electron emission were developed using 4-grid low energy electron diffraction (LEED) optics. The total secondary electron yield from a Ni(110) surface was continuously measured from the sample current as surface contamination increased from reactions with background gases in the ultrahigh vacuum chamber. Auger electron spectroscopy (AES) and temperature programmed desorption (TPD) were used to examine the composition and impurity levels on the Ni(110) surface. The total secondary electron yield was also measured at different incident angles. Thank you to the Princeton Plasma Physics Laboratory and the Department of Energy for the opportunity to work on this project through the Science Undergraduate Laboratory Internships.

  6. The effects of impurities and incidence angle on the secondary electron emission of Ni(110)

    NASA Astrophysics Data System (ADS)

    Lazar, Hadar; Patino, Marlene; Raitses, Yevgeny; Koel, Bruce; Gentile, Charles; Feibush, Eliot

    The investigation of secondary electron emission (SEE) of conducting materials used for magnetic fusion devices and plasma thrusters is important for determining device lifetime and performance. Methods to quantify the secondary electron emission from conducting materials and to characterize the effects that impurities and incidence angles have on secondary electron emission were developed using 4-grid low energy electron diffraction (LEED) optics. The total secondary electron yield from a Ni(110) surface was continuously measured from the sample current as surface contamination increased from reactions with background gases in the ultrahigh vacuum chamber. Auger electron spectroscopy (AES) and temperature programmed desorption (TPD) were used to examine the composition and impurity levels on the Ni(110) surface. The total secondary electron yield was also measured at different incidence angles. Thank you to the Princeton Plasma Physics Laboratory (PPPL) and the Department of Energy (DOE) for the opportunity to work on this project through the Science Undergraduate Laboratory Internships (SULI).

  7. Effect of aquatic weeds on methane emission from submerged paddy soil.

    PubMed

    Inubushi, K; Sugii, H; Nishino, S; Nishino, E

    2001-06-01

    Paddy fields are one of the dominant anthropogenic sources of methane emission to the atmosphere, and the main passageway of methane from paddy soil is through the rice plant. However, the effect of aquatic weeds on methane emission from rice paddies has not been properly evaluated yet. Methane emission from weeded pots and unweeded ones with anaerobic paddy soil was measured throughout the period of rice growth. More than double the amount of methane was emitted from weeded pots compared with unweeded ones. Peroxidase activity of rice root was not different between weeded and unweeded pots. However, methanogenic bacteria populations were higher in weeded pots than in unweeded ones, while methane oxidation activity, measured by the propylene oxidation technique, was higher in unweeded pots than in weeded ones. Methane oxidation activity of roots from three typical aquatic weeds in paddy fields, Lipocarpha sp., Rotala indica, and Ludwigia epilobioides, was higher than that of rice plants, while lower stems of these aquatic plants showed similar or lower activity compared with the same areas of rice plants. These results indicate that the role of aquatic weeds in paddy soil in methane emission should not be overlooked in evaluating mitigation options for reducing methane emission from paddy fields.

  8. An Investigation on the Effects of Ship Sourced Emissions in Izmir Port, Turkey

    PubMed Central

    Saraçoğlu, Halil; Kılıç, Alper

    2013-01-01

    Maritime transportation is a major source of climate change and air pollution. Shipping emissions cause severe impacts on health and environment. These effects of emissions are emerged especially in territorial waters, inland seas, canals, straits, bays, and port regions. In this paper, exhaust gas emissions from ships in Izmir Port, which is one of the main ports in Turkey, are calculated by the ship activity-based methodology. Total emissions from ships in the port is estimated as 1923 ton y−1 for NOx, 1405 ton y−1 for SO2, 82753 ton y−1 for CO2, ton y−1 for HC, and 165 ton y−1 for PM in the year 2007. These emissions are classified regarding operation modes and types of ships. The results are compared with the other studies including amounts of exhaust pollutants generated by ships. According to the findings, it is clear that the ships calling the Izmir Port are important air polluting causes of the Izmir city and its surroundings. PMID:24198720

  9. Effects of Cold Temperature and Ethanol Content on VOC Emissions from Light-Duty Gasoline Vehicles.

    PubMed

    George, Ingrid J; Hays, Michael D; Herrington, Jason S; Preston, William; Snow, Richard; Faircloth, James; George, Barbara Jane; Long, Thomas; Baldauf, Richard W

    2015-11-03

    Emissions of speciated volatile organic compounds (VOCs), including mobile source air toxics (MSATs), were measured in vehicle exhaust from three light-duty spark ignition vehicles operating on summer and winter grade gasoline (E0) and ethanol blended (E10 and E85) fuels. Vehicle testing was conducted using a three-phase LA92 driving cycle in a temperature-controlled chassis dynamometer at two ambient temperatures (-7 and 24 °C). The cold start driving phase and cold ambient temperature increased VOC and MSAT emissions up to several orders of magnitude compared to emissions during other vehicle operation phases and warm ambient temperature testing, respectively. As a result, calculated ozone formation potentials (OFPs) were 7 to 21 times greater for the cold starts during cold temperature tests than comparable warm temperature tests. The use of E85 fuel generally led to substantial reductions in hydrocarbons and increases in oxygenates such as ethanol and acetaldehyde compared to E0 and E10 fuels. However, at the same ambient temperature, the VOC emissions from the E0 and E10 fuels and OFPs from all fuels were not significantly different. Cold temperature effects on cold start MSAT emissions varied by individual MSAT compound, but were consistent over a range of modern spark ignition vehicles.

  10. Comparison of Aspect Angle Effect on Stimulated Electromagnetic Emissions using HAARP and EISCAT facilities

    NASA Astrophysics Data System (ADS)

    Fu, H.; Scales, W.; Bernhardt, P. A.; Briczinski, S. J.; Kosch, M. J.; Senior, A.; Rietveld, M. T.; Yeoman, T. K.; Ruohoniemi, J. M.

    2012-12-01

    A high power HF heating transmitter can excite a broad spectrum of Stimulated Electromagnetic Emission (SEE) lines by O-mode and X-mode heating. These emissions can provide useful diagnostics during modification of the ionosphere. The HAARP 3.6MW transmitter beam angle has been confirmed as an important factor for exciting ion acoustic (IA) and electrostatic ion cyclotron waves (EIC) by Magnetized Stimulated Brillouin Scatter (MSBS). The newly observed associated SEE spectral emissions by the MSBS process are considered to originate from cascading processes at the upper hybrid resonance region. These beam angle effects on SEE features have been observed during second electron gyro-harmonic heating experiments. These will be studied and described in much greater detail with a systematic investigation here using two facilities using both the EISCAT facility in Tromso, Norway as well as the HAARP facility. It will be shown that both MSBS emissions and ion Bernstein SEE emissions are observed simultaneously with the pump frequency near the third and second electron gyro harmonic and show important systematic variation with beam angle that can be exploited for important diagnostic purposes. At the EISCAT heating facility, SEE features studied near the third and fourth electron gyro-harmonic with simultaneous electron temperature measurement were observed with strong field aligned irregularities. Importance of the proximity of the pump frequency to the gyro-harmonic on the narrowband SEE spectrum will be compared between both facilities as well.

  11. An investigation on the effects of ship sourced emissions in Izmir Port, Turkey.

    PubMed

    Saraçoğlu, Halil; Deniz, Cengiz; Kılıç, Alper

    2013-01-01

    Maritime transportation is a major source of climate change and air pollution. Shipping emissions cause severe impacts on health and environment. These effects of emissions are emerged especially in territorial waters, inland seas, canals, straits, bays, and port regions. In this paper, exhaust gas emissions from ships in Izmir Port, which is one of the main ports in Turkey, are calculated by the ship activity-based methodology. Total emissions from ships in the port is estimated as 1923 ton y⁻¹ for NO(x), 1405 ton y⁻¹ for SO₂, 82753 ton y⁻¹ for CO₂, ton y⁻¹ for HC, and 165 ton y⁻¹ for PM in the year 2007. These emissions are classified regarding operation modes and types of ships. The results are compared with the other studies including amounts of exhaust pollutants generated by ships. According to the findings, it is clear that the ships calling the Izmir Port are important air polluting causes of the Izmir city and its surroundings.

  12. Effect of microstructure of graphite on the nonreductive thermal ion emission in thermal ionization mass spectrometry.

    PubMed

    Wei, H Z; Jiang, S Y; Xiao, Y K

    2010-02-25

    The emission behavior of polyatomic ions in the ionization source of thermal ionization mass spectrometry (TIMS) was investigated. The results suggest that the presence of a graphite promoter plays a key role for the formation and stable emission of polyatomic ions, such as M(2)X(+), M(2)BO(2)(+), Cs(2)NO(2)(+), and Cs(2)CNO(+). Our data further implied that the intensity of M(2)X(+) and M(2)BO(2)(+) increases and the emission temperature decreases with increasing cationic and anionic radius. During the boron isotopic measurement using the Cs(2)BO(2)(+)-graphite-PTIMS method, the isobaric interference ion Cs(2)CNO(+) cannot be transformed from nitrate or organic compounds containing an amide group but can be induced by the existence of trace amounts of boron because of its special electron-deficiency property (B(3+)). Characterization on the planar crystalline structure of various graphite samples with SEM, TEM, and Raman spectroscopy confirmed the relationship of the emission capacity of polyatomic ions and the crystal microstructure of graphite and provides direct evidence that graphite with a perfect parallel and equidistant layer orientation shows a beneficial effect on the emission of polyatomic ions in TIMS. The mechanism study on the formation of polyatomic ions opens the possibility to establish high precision methods for isotopic composition analysis of more nonmetal elements with the TIMS technique.

  13. Atmospheric inversion for cost effective quantification of city CO2 emissions

    NASA Astrophysics Data System (ADS)

    Wu, L.; Broquet, G.; Ciais, P.; Bellassen, V.; Vogel, F.; Chevallier, F.; Xueref-Remy, I.; Wang, Y.

    2015-11-01

    Cities, currently covering only a very small portion (< 3 %) of the world's land surface, directly release to the atmosphere about 44 % of global energy-related CO2, and are associated with 71-76 % of CO2 emissions from global final energy use. Although many cities have set voluntary climate plans, their CO2 emissions are not evaluated by Monitoring, Reporting and Verification (MRV) procedures that play a key role for market- or policy-based mitigation actions. Here we propose a monitoring tool that could support the development of such procedures at the city scale. It is based on an atmospheric inversion method that exploits inventory data and continuous atmospheric CO2 concentration measurements from a network of stations within and around cities to estimate city CO2 emissions. We examine the cost-effectiveness and the performance of such a tool. The instruments presently used to measure CO2 concentrations at research stations are expensive. However, cheaper sensors are currently developed and should be useable for the monitoring of CO2 emissions from a megacity in the near-term. Our assessment of the inversion method is thus based on the use of several types of hypothetical networks, with a range of numbers of sensors sampling at 25 m a.g.l. The study case for this assessment is the monitoring of the emissions of the Paris metropolitan area (~ 12 million inhabitants and 11.4 Tg C emitted in 2010) during the month of January 2011. The performance of the inversion is evaluated in terms of uncertainties in the estimates of total and sectoral CO2 emissions. These uncertainties are compared to a notional ambitious target to diagnose annual total city emissions with an uncertainty of 5 % (2-sigma). We find that, with 10 stations only, which is the typical size of current pilot networks that are deployed in some cities, the uncertainty for the 1-month total city CO2 emissions is significantly reduced by the inversion by ~ 42 % but still corresponds to an annual

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

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

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

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

    PubMed Central

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

    2017-01-01

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

  16. Effect of secondary emission on the argon plasma afterglow with large dust density

    SciTech Connect

    Denysenko, I. B.; Azarenkov, N. A.; Burmaka, G. P.; Stefanović, I.

    2015-02-15

    A zero-dimensional, space-averaged model for argon plasma afterglow with large dust density is developed. In the model, three groups of electrons in the plasma afterglow are assumed: (i) thermal electrons with Maxwellian distribution, (ii) energetic electrons generated by metastable-metastable collisions (metastable pooling), and (iii) secondary electrons generated at collisions of ions with the electrodes, which have sufficiently large negative voltages in the afterglow. The model calculates the time-dependencies for electron densities in plasma afterglow based on experimental decay times for metastable density and electrode bias. The effect of secondary emission on electron density in the afterglow is estimated by varying secondary emission yields. It is found that this effect is less important than metastable pooling. The case of dust-free plasma afterglow is considered also, and it is found that in the afterglow the effect of secondary emission may be more important than metastable pooling. The secondary emission may increase thermal electron density n{sub e} in dust-free and dusty plasma afterglows on a few ten percentages. The calculated time dependencies for n{sub e} in dust-free and dusty plasma afterglows describe well the experimental results.

  17. Effects of multiple scattering and thermal emission on target-background signatures sensed through obscuring atmospheres

    NASA Astrophysics Data System (ADS)

    Sutherland, Robert A.; Thompson, Jill C.; Klett, James D.

    2000-07-01

    We report on the application of a recently developed method for producing exact solutions of the thermal vision of the radiative transfer equation1. The method is demonstrated to be accurate to within five significant figures when compared with the one dimensional plane layer solutions published by van de Hulst2, and, has the added capability for treating discrete localized, aerosol clouds of spherical and cylindrical symmetry. The method, described in detail in a companion paper1, is only briefly summarized here, where our main purpose is to demonstrate the utility of the method for calculating emissivity functions of finite aerosol clouds of arbitrary optical thickness and albedo, and most likely to occur on the modern cluttered battlefield. The emissivity functions are then used to determine apparent temperatures including effects of both internal thermal emission and in- scatter from the ambient surroundings. We apply the results to four generic scenarios, including the mid and far IR and a hypothetical full spectrum band. In all cases, calculations show that errors on the order of several degrees in the sensed temperature can occur if cloud emissivity is not accounted for; with errors being most pronounced at the higher values of optical depth and albedo. We also demonstrate that significant discrepancies can occur when comparing results from different spectral bands, especially for the mid IR which consistently shows higher apparent temperatures than the other bands, including the full spectrum case. Results of emissivity calculations show that in almost no case can one justify the simple Beer's Law model that essentially ignores emissive/scattering effects; however, there is reason for optimism in the use of other simplifying first and higher order approximations used in some contemporary models. The present version of the model treats only Gaussian aerosol distributions and isotropic scattering; although neither assumption necessarily represents a

  18. Health effects of subchronic exposure to diesel-water emulsion emission.

    PubMed

    Reed, M D; Blair, L F; Burling, K; Daly, I; Gigliotti, A P; Gudi, R; Mercieca, M D; McDonald, J D; Naas, D J; O'callaghan, J P; Seilkop, S K; Ronsko, N L; Wagner, V O; Kraska, R C

    2005-12-15

    The U.S. Environmental Protection Agency (EPA) National Ambient Air Quality Standards for ozone and particulate matter are requiring urban nonattainment areas to implement pollution-reduction strategies for anthropogenic source emissions. A type of fuel shown to decrease combustion emissions components versus traditional diesel fuels is the diesel-water emulsion. The Lubrizol Corporation in conjunction with Lovelace Respiratory Research Institute and several subcontracting laboratories recently conducted a rodent health assessment of inhaled combustion emissions of PuriNO(x) diesel fuel emulsion. Combustion emissions from either of two 2001 model Cummins 5.9-L ISB engines were diluted with charcoal-filtered air to exposure concentrations of 100, 200, and 400 microg total particulate matter/m(3). The engines were operated on a continuously repeating, heavy-duty certification cycle (U.S. Code of Federal Regulations, Title 40, Chapter I) using Rotella-T 15W-40 engine oil. Nitrogen oxide and particulate matter were reduced when engines were operated on PuriNO(x) versus California Air Resources Board diesel fuel under these conditions. Male and female F344 rats were housed in Hazleton H2000 exposure chambers and exposed to exhaust atmospheres 6 h/day, 5 days/wk for the first 11 wk and 7 days/wk threafter. Exposures ranged from 58 to 70 days, depending on the treatment group. Indicators of general toxicity (body weight, organ weight, clinical pathology, and histopathology), neurotoxicity (glial fibrillary acidic protein assay), genotoxicity (Ames assay, micronucleus, sister chromatid exchange), and reproduction and development were measured. Overall, effects observed were mild. Emulsion combustion emissions were not associated with neurotoxicity, reproductive/developmental toxicity, or in vivo genotoxicity. Small decreases in serum cholesterol and small increases in platelet values in some groups of exposed animals were observed. Particulate matter accumulation within

  19. Fire environment effects on particulate matter emission factors in southeastern U.S. pine-grasslands

    NASA Astrophysics Data System (ADS)

    Robertson, Kevin M.; Hsieh, Yuch P.; Bugna, Glynnis C.

    2014-12-01

    Particulate matter (PM) emission factors (EFPM), which predict particulate emissions per biomass consumed, have a strong influence on event-based and regional PM emission estimates and inventories. PM < 2.5 μm aerodynamic diameter (PM2.5), regulated for its impacts to human health and visibility, is of special concern. Although wildland fires vary widely in their fuel conditions, meteorology, and fire behavior which might influence combustion reactions, the EFPM2.5 component of emission estimates is typically a constant for the region or general fuel type being assessed. The goal of this study was to use structural equation modeling (SEM) to identify and measure effects of fire environment variables on EFPM2.5 in U.S. pine-grasslands, which contribute disproportionately to total U.S. PM2.5 emissions. A hypothetical model was developed from past literature and tested using 41 prescribed burns in northern Florida and southern Georgia, USA with varying years since previous fire, season of burn, and fire direction of spread. Measurements focused on EFPM2.5 from flaming combustion, although a subset of data considered MCE and smoldering combustion. The final SEM after adjustment showed EFPM2.5 to be higher in burns conducted at higher ambient temperatures, corresponding to later dates during the period from winter to summer and increases in live herbaceous vegetation and ambient humidity, but not total fine fuel moisture content. Percentage of fine fuel composed of pine needles had the strongest positive effect on EFPM2.5, suggesting that pine timber stand volume may significantly influence PM2.5 emissions. Also, percentage of fine fuel composed of grass showed a negative effect on EFPM2.5, consistent with past studies. Results of the study suggest that timber thinning and frequent prescribed fire minimize EFPM2.5 and total PM2.5 emissions on a per burn basis, and that further development of PM emission models should consider adjusting EFPM2.5 as a function of common

  20. Effects of N-Acetylcysteine on Thresholds and Otoacoustic Emissions Following Noise Exposure

    DTIC Science & Technology

    2004-12-01

    wearing ear plugs, muffs, etc.. The current study evaluated the effectiveness of one antioxidant, N- acetylcysteine ( NAC ), on temporary cochlear changes...EFFECTS OF N- ACETYLCYSTEINE ON THRESHOLDS AND OTOACOUSTIC EMISSIONS FOLLOWING NOISE EXPOSURE Barbara Acker-Mills, Ph.D*., CPT Martin Robinette...in humans by using both behavioral and physiological measures. Two levels of supplement (900 mg of NAC or placebo) and two levels of noise (60 dB

  1. Effects of quantum interference in spectra of cascade spontaneous emission from multilevel systems

    NASA Astrophysics Data System (ADS)

    Makarov, A. A.; Yudson, V. I.

    2016-12-01

    A general expression for the spectrum of cascade spontaneous emission from an arbitrary multilevel system is presented. Effects of the quantum interference of photons emitted in different transitions are analyzed. These effects are especially essential when the transition frequencies are close. Several examples are considered: (i) Three-level system; (ii) Harmonic oscillator; (iii) System with equidistant levels and equal rates of the spontaneous decay for all the transitions; (iv) Dicke superradiance model.

  2. Effects of crop residue returning on nitrous oxide emissions in agricultural soils

    NASA Astrophysics Data System (ADS)

    Shan, Jun; Yan, Xiaoyuan

    2013-06-01

    Crop residue returning is a common practice in agricultural system that consequently influences nitrous oxide (N2O) emissions. Much attention has been focused on the effects of crop residue on N2O release. However, no systematic result has yet been drawn because environmental factors among different studies vary. A meta-analysis was described to integrate 112 scientific assessments of crop residue returning on N2O emissions in this study. Results showed that crop residue returning, when averaged across all studies, had no statistically significant effect on N2O release compared with control treatments. However, the range of effects of crop residue returning on N2O emission was significantly affected by synthetic nitrogen (N) fertilizer application, type of crop residue, specific manner in which crop residue has returned, and type of land-use. N2O release was significantly inhibited by 11.7% and 27.1% (P < 0.05) when crop residue was with synthetic N fertilizer and when type of land-use was paddy, respectively. While N2O emissions were significantly enhanced by 42.1% and 23.5% (P < 0.05) when crop residue was applied alone and when type of land-use was upland, respectively. N2O emissions were likewise increased when crop residue with lower C/N ratio was used, mulching of crop residue was performed, and type of land-use was fallow. Our study provides the first quantitative analysis of crop residue returning on N2O emissions, indicating that crop residue returning has no statistically significant effect on N2O release at regional scale, and underlining that the Intergovernmental Panel on Climate Change guidelines should take the opposite effects of crop residue returning on upland and paddy into account when estimating the N2O emission factor of crop residue for different land-use types. Given that most of data are dominated by certain types of crop residue and specific application methods, more field data are required to reduce uncertainty.

  3. Lifetime-vibrational interference effects in resonantly excited x-ray emission spectra of CO

    SciTech Connect

    Skytt, P.; Glans, P.; Gunnelin, K.

    1997-04-01

    The parity selection rule for resonant X-ray emission as demonstrated for O{sub 2} and N{sub 2} can be seen as an effect of interference between coherently excited degenerate localized core states. One system where the core state degeneracy is not exact but somewhat lifted was previously studied at ALS, namely the resonant X-ray emission of amino-substituted benzene (aniline). It was shown that the X-ray fluorescence spectrum resulting from excitation of the C1s at the site of the {open_quotes}aminocarbon{close_quotes} could be described in a picture separating the excitation and the emission processes, whereas the spectrum corresponding to the quasi-degenerate carbons could not. Thus, in this case it was necessary to take interference effects between the quasi-degenerate intermediate core excited states into account in order to obtain agreement between calculations and experiment. The different vibrational levels of core excited states in molecules have energy splittings which are of the same order of magnitude as the natural lifetime broadening of core excitations in the soft X-ray range. Therefore, lifetime-vibrational interference effects are likely to appear and influence the band shapes in resonant X-ray emission spectra. Lifetime-vibrational interference has been studied in non-resonant X-ray emission, and in Auger spectra. In this report the authors discuss results of selectively excited soft X-ray fluorescence spectra of molecules, where they focus on lifetime-interference effects appearing in the band shapes.

  4. Water stress, temperature, and light effects on isoprene emission and photosynthesis of Kudzu leaves

    SciTech Connect

    Sharkey, T.D.; Loreto, F. )

    1993-05-01

    Kudzu (Pueraia lobata (Willd) Ohwi.) emits isoprene, a hydrocarbon which can significantly affect atmospheric chemistry. Isoprene emission under standard conditions of 1000 [mu]mol photons[center dot]M[sup [minus]2][center dot]S[sup [minus]1] and 30[degrees]C developed only after the leaf bad reached full expansion and was not maximal until up to two weeks past the point of full expansion of the leaf. Isoprene emission from kudzu was stimulated by increases in temperature and photon flux density (up to 3000 [mu]mol photons[center dot]m[sup [minus]2][center dot]s[sup [minus]1]). For unstressed plants, 20 % of the carbon fixed in photosynthesis was reemitted as isoprene at 1000 [mu]mol photons[center dot]m[sup [minus]2][center dot]S[sup [minus]1]. Following the relief of water stress, photosynthesis recovered to the prestress rate but isoprene emission increased up to five times the prestress rate. At 1000 [mu]mol photons[center dot]M[sup [minus]2][center dot]S[sup [minus]1] and 35[degrees]C, 67% of the carbon fixed in photosynthesis was reemitted as isoprene eight days after water stress. For some leaves the rate of isoprene emission exceeded 500 nmol[center dot]M[sup [minus]2][center dot]S[sup [minus]1], substantially higher than ever reported before. Leaves of plants grown at less than 20[degrees]C did not make isoprene until an inductive treatment was given. Withholding water from plants or keeping leaves at 30[degrees]C induced isoprene emission. The observation of rapid and dramatic changes in the rate of isoprene emission from leaves in response to water stress and temperature may indicate that isoprene emission improves the ability of plants to cope with these conditions. With the new information on temperature and water stress effects on isoprene emission we speculate on possible reasons for isoprene emission from plants.

  5. The effects of potential changes in United States beef production on global grazing systems and greenhouse gas emissions

    NASA Astrophysics Data System (ADS)

    Dumortier, Jerome; Hayes, Dermot J.; Carriquiry, Miguel; Dong, Fengxia; Du, Xiaodong; Elobeid, Amani; Fabiosa, Jacinto F.; Martin, Pamela A.; Mulik, Kranti

    2012-06-01

    We couple a global agricultural production and trade model with a greenhouse gas model to assess leakage associated with modified beef production in the United States. The effects on emissions from agricultural production (i.e., methane and nitrous oxide emissions from livestock and crop management) as well as from land-use change, especially grazing system, are assessed. We find that a reduction of US beef production induces net carbon emissions from global land-use change ranging from 37 to 85 kg CO2-equivalent per kg of beef annualized over 20 years. The increase in emissions is caused by an inelastic domestic demand as well as more land-intensive cattle production systems internationally. Changes in livestock production systems such as increasing stocking rate could partially offset emission increases from pasture expansion. In addition, net emissions from enteric fermentation increase because methane emissions per kilogram of beef tend to be higher globally.

  6. Nutrient Recovery and Emissions of Ammonia, Nitrous Oxide, and Methane from Animal Manure in Europe: Effects of Manure Treatment Technologies.

    PubMed

    Hou, Yong; Velthof, Gerard L; Lesschen, Jan Peter; Staritsky, Igor G; Oenema, Oene

    2017-01-03

    Animal manure contributes considerably to ammonia (NH3) and greenhouse gas (GHG) emissions in Europe. Various treatment technologies have been implemented to reduce emissions and to facilitate its use as fertilizer, but a systematic analysis of these technologies has not yet been carried out. This study presents an integrated assessment of manure treatment effects on NH3, nitrous oxide (N2O) and methane (CH4) emissions from manure management chains in all countries of EU-27 in 2010 using the MITERRA-Europe model. Effects of implementing 12 treatment technologies on emissions and nutrient recovery were further explored through scenario analyses; the level of implementation corresponded to levels currently achieved by forerunner countries. Manure treatment decreased GHG emissions from manures in EU countries by 0-17% in 2010, with the largest contribution from anaerobic digestion; the effects on NH3 emissions were small. Scenario analyses indicate that increased use of slurry acidification, thermal drying, incineration and pyrolysis may decrease NH3 (9-11%) and GHG (11-18%) emissions; nitrification-denitrification treatment decreased NH3 emissions, but increased GHG emissions. The nitrogen recovery (% of nitrogen excreted in housings that is applied to land) would increase from a mean of 57% (in 2010) to 61% by acidification, but would decrease to 48% by incineration. Promoting optimized manure treatment technologies can greatly contribute to achieving NH3 and GHG emission targets set in EU environmental policies.

  7. Effects of dietary fiber and reduced crude protein on ammonia emission from laying-hen manure.

    PubMed

    Roberts, S A; Xin, H; Kerr, B J; Russell, J R; Bregendahl, K

    2007-08-01

    Ammonia (NH(3)) emission is a major concern for the poultry industry. The objective of this research was to determine whether inclusion of dietary fiber and a reduced dietary CP content would decrease NH(3) emission from laying-hen manure. A total of 256 Hy-Line W-36 hens were fed diets with 2 levels of CP (normal and reduced) and 4 fiber treatments in a 2 x 4 factorial arrangement. The fiber treatments included a corn and soybean meal-based control diet and diets formulated with either 10.0% corn dried distillers grains with solubles (DDGS), 7.3% wheat middlings (WM), or 4.8% soybean hulls (SH) to contribute equal amounts of additional neutral detergent fiber. The CP contents of the reduced-CP diets were approximately 1 percentage unit lower than those of the normal-CP diets. All diets were formulated on the basis of digestible amino acid content and were formulated to be isoenergetic. Fresh manure was collected such that pH, uric acid, and Kjeldahl N contents could be measured. The NH(3) emission from manure was measured over 7 d by placing pooled 24-h manure samples in NH(3) emission vessels. Data were analyzed by ANOVA with Dunnett's multiple-comparisons procedure to compare results from the fiber treatments with the control, whereas the main effect of protein was used to compare the normal- and reduced-CP treatments. Dietary corn DDGS, WM, or SH lowered (P emission from 3.9 g/kg of DM manure for the control to 1.9, 2.1, and 2.3 g/kg of DM manure, respectively, and lowered (P < 0.05) the daily NH(3) emission rate. Results of this study showed that dietary inclusion of 10.0% corn DDGS, 7.3% WM, or 4.8% SH lowered NH(3) emission from laying-hen manure; however, reducing the CP content by 1 percentage unit had no measurable effect on NH(3) emission.

  8. The dynamics of grazed woodlands in southwest Queensland, Australia and their effect on greenhouse gas emissions.

    PubMed

    Moore, J L; Howden, S M; McKeon, G M; Carter, J O; Scanlan, J C

    2001-09-01

    This study outlines the development of an approach to evaluate the sources, sinks, and magnitudes of greenhouse gas emissions from a grazed semiarid rangeland dominated by mulga (Acacia aneura) and how these emissions may be altered by changes in management. This paper describes the modification of an existing pasture production model (GRASP) to include a gas emission component and a dynamic tree growth and population model. An exploratory study was completed to investigate the likely impact of changes in burning practices and stock management on emissions. This study indicates that there is a fundamental conflict between maintaining agricultural productivity and reducing greenhouse gas emissions on a given unit of land. Greater agricultural productivity is allied with the system being an emissions source while production declines and the system becomes a net emissions sink as mulga density increases. Effective management for sheep production results in the system acting as a net source (approximately 60-200 kg CO2 equivalents/ha/year). The magnitude of the source depends on the management strategies used to maintain the productivity of the system and is largely determined by starting density and average density of the mulga over the simulation period. Prior to European settlement, it is believed that the mulga lands were burnt almost annually. Simulations indicate that such a management approach results in the system acting as a small net sink with an average net absorption of greenhouse gases of 14 kg CO2 equivalents/ha/year through minimal growth of mulga stands. In contrast, the suppression of fire and the introduction of grazing results in thickening of mulga stands and the system can act as a significant net sink absorbing an average of 1000 kg CO2 equivalents/ha/year. Although dense mulga will render the land largely useless for grazing, land in this region is relatively inexpensive and could possibly be developed as a cost-effective carbon offset for

  9. Inhalation of primary motor vehicle emissions: Effects of urbanpopulation and land area

    SciTech Connect

    Marshall, Julian D.; McKone, Thomas E.; Nazaroff, William W.

    2004-06-14

    Urban population density can influence transportation demand, as expressed through average daily vehicle-kilometers traveled per capita (VKT). In turn, changes in transportation demand influence total passenger vehicle emissions. Population density can also influence the fraction of total emissions that are inhaled by the exposed urban population. Equations are presented that describe these relationships for an idealized representation of an urban area. Using analytic solutions to these equations, we investigate the effect of three changes in urban population and urban land area (infill, sprawl, and constant-density growth) on per capita inhalation intake of primary pollutants from passenger vehicles. The magnitude of these effects depends on density-emissions elasticity ({var_epsilon}{sub e}), a normalized derivative relating change in population density to change in vehicle emissions. For example, if urban population increases, per capita intake is less with infill development than with constant-density growth if {var_epsilon}{sub e} is less than -0.5, while for {var_epsilon}{sub e} greater than -0.5 the reverse is true.

  10. Effect of application variables on emissions and distribution of fumigants applied via subsurface drip irrigation.

    PubMed

    Papiernik, Sharon K; Dungan, Robert S; Zheng, Wei; Guo, Mingxin; Lesch, Scott M; Yates, Scott R

    2004-11-01

    Soil fumigation is useful for controlling soil-borne pests and diseases in high-cash-value crops. Fumigants are highly volatile, and approaches to reduce atmospheric emissions are required to protect human and environmental health. Application of fumigants through drip irrigation has been proposed as a means to decrease fumigant emissions, improve fumigant distribution in soil, and minimize worker exposure. These experiments were conducted to investigate the effect of the configuration of the drip system on the volatilization and distribution of the fumigants 1,3-dichloropropene (1,3-D), propargyl bromide (PrBr), and methyl isothiocyanate (MITC) in bedded systems. Results indicated that changing the drip emitter spacing and using multiple drip lines in each bed had little effect on the emissions and distribution of any fumigant. Increasing the depth of application from 15 to 30 cm reduced volatilization of MITC by approximately 20 to >90%; emissions were reduced due to a decrease in the flux from the bed top, and deeper injection did not change the amount of fumigant volatilized from the bed side slope and furrow. Increasing the application depth resulted in a slight decrease in the rate of fumigant dissipation in soil, indicating the potential for some improvement in pest-control efficacy with deeper application.

  11. It is premature to include non-CO 2 effects of aviation in emission trading schemes

    NASA Astrophysics Data System (ADS)

    Forster, Piers M. de F.; Shine, Keith P.; Stuber, Nicola

    The recent G8 Gleneagles climate statement signed on 8 July 2005 specifically mentions a determination to lessen the impact of aviation on climate [ Gleneagles, 2005. The Gleneagles communique: climate change, energy and sustainable development. http://www.fco.gov.uk/Files/kfile/PostG8_Gleneagles_Communique.pdf]. In January 2005 the European Union Emission Trading Scheme (ETS) commenced operation as the largest multi-country, multi-sector ETS in the world, albeit currently limited only to CO 2 emissions. At present the scheme makes no provision for aircraft emissions. However, the UK Government would like to see aircraft included in the ETS and plans to use its Presidencies of both the EU and G8 in 2005 to implement these schemes within the EU and perhaps internationally. Non-CO 2 effects have been included in some policy-orientated studies of the impact of aviation but we argue that the inclusion of such effects in any such ETS scheme is premature; we specifically argue that use of the Radiative Forcing Index for comparing emissions from different sources is inappropriate and that there is currently no metric for such a purpose that is likely to enable their inclusion in the near future.

  12. Estimation of Photon Effects on Townsend Discharges for SecondaryElectronEmission Coefficient Measurements

    NASA Astrophysics Data System (ADS)

    Yoshinaga, Tomokazu; Akashi, Haruaki

    2015-09-01

    A Monte Carlo simulation (MCS) is applied to investigate the secondary electron emission in Argon Townsend discharges. The influxes of ions, photons and metastable species onto the cathode surface are estimated simply from the number of inelastic collisions. The effect of photons becomes significant especially under higher pd conditions since the photon influx increases. This suggests the possibility of the estimation of the secondary electron emission coefficient of photons by examining breakdown voltage characteristics (Paschen curves). The effect of metastable species is much smaller than those of ions and photons and is negligible. The Paschen curves evaluated with MCS agrees well with the results of one-dimensional fluid model simulation when the photon effect is neglected, showing the necessity of further improvement. Supported by JSPS KAKENHI Grant Number 26820108.

  13. Dust emissions from undisturbed and disturbed, crusted playa surfaces: Cattle trampling effects

    NASA Astrophysics Data System (ADS)

    Baddock, Matthew C.; Zobeck, Ted M.; Van Pelt, R. Scott; Fredrickson, Ed L.

    2011-06-01

    Dry playa lake beds can be significant sources of fine dust emission. This study used a portable field wind tunnel to quantify the PM 10 emissions from a bare, fine-textured playa surface located in the far northern Chihuahua Desert. The natural, undisturbed crust and its subjection to two levels of animal disturbance (one and ten cow passes) were tested. The wind tunnel generated dust emissions under controlled conditions for firstly an initial blow-off of the surface, followed by two longer runs with sand added to the flow as an abrader material. Dust was measured using a GRIMM particle monitor. For the study playa, no significant differences in PM 10 concentration and emission flux were found between the untrampled surface and following a single animal pass. This was the case for both the initial blow-offs and tests on plots under a steady abrader rate. Significantly higher dust loading was only associated with the effect of 10 animal passes. In the blow-offs, the higher PM 10 yield after 10 passes reflected the greater availability of easily entrainable fine particles. Under abrasion, the effect of the heaviest trampling increased the emission flux by a third and abrasion efficiency by around 50% more than values on the untrampled surface. This enhanced abrasion efficiency persisted for a 30 min period under abrasion before the positive effect of the disturbance was no longer evident. The findings highlight the role of a threshold of disturbance that determines if supply-limited surfaces will exhibit enhanced wind erosion or not after undergoing perturbation.

  14. Pro-Inflammatory Effects of Cook Stove Emissions on Human Bronchial Epithelial Cells

    PubMed Central

    Hawley, Brie; Volckens, John

    2012-01-01

    Approximately half the world’s population uses biomass fuel for indoor cooking and heating. This form of combustion typically occurs in open fires or primitive stoves. Human exposure to emissions from indoor biomass combustion is a global health concern, causing an estimated 1.5 million premature deaths each year. Many ‘improved’ stoves have been developed to address this concern; however, studies that examine exposure-response with cleaner-burning, more efficient stoves are few. The objective of this research was to evaluate the effects of traditional and cleaner burning stove emissions on an established model of the bronchial epithelium. We exposed well-differentiated, normal human bronchial epithelial (NHBE) cells to emissions from a single biomass combustion event using either a traditional three-stone fire or one of two energy-efficient stoves. Air-liquid interface cultures were exposed using a novel, aerosol-to-cell deposition system. Cellular expression of a panel of three pro-inflammatory markers was evaluated at 1 and 24 hours following exposure. Cells exposed to emissions from the cleaner burning stoves generated significantly fewer amounts of pro-inflammatory markers than cells exposed to emissions from a traditional, three stone fire. Particulate matter emissions from each cookstove were substantially different, with the three-stone fire producing the largest concentrations of particles (by both number and mass). This study supports emerging evidence that more efficient cookstoves have the potential to reduce respiratory inflammation in settings where solid fuel combustion is used to meet basic domestic needs. PMID:22672519

  15. Global warming mitigation by sulphur loading in the atmosphere: Required emissions and possible side effects

    NASA Astrophysics Data System (ADS)

    Eliseev, A. V.; Mokhov, I. I.; Chernokulsky, A. V.; Karpenko, A. A.

    2009-04-01

    An approach to mitigate the global warming via sulphur loading in the stratosphere (geoengineering) is studied employing a large ensemble of numerical experiments with the climate model of intermediate complexity developed at the A.M.Obukhov Institute of Atmospheric Physics RAS (IAP RAS CM). The model is forced by the historical+SRES A1B anthropogenical greenhouse gases+tropospheric sulphates scenario for 1860-2100 with an additional sulphur emissions in the stratosphere in the 21st century. Different ensemble members were constructed by varying emission intensity, residence time, optical properites, and horizontal distributions of stratospheric sulphates. In addition, starting and ending years of applied emissions are varied between different ensemble members. Given global loading of the sulphates in the stratosphere, at the global basis, the most efficient latitudinal distribution of geoengineering aerosols is that peaked between 50∘N and 70∘N. Uniform latitudinal distribution of stratospheric sulphates is slightly less efficient. Sulphur emissions in the stratosphere required to stop the global temperature at the level corresponding to the mean value for 2000-2010 amount 5 - 10 TgS/yr in year 2050 and > 10 TgS/yr in year 2100. This is not a small part of the current emissions of tropospheric sulphates. Moreover, even if the global warming is stopped, temperature changes in different regions still occur with a magnitude up to 1 K. Their horizontal pattern depends on implied latitudinal distribution of stratospheric sulphates. If the geoengineering emissions are stopped, their climatic effect is removed within a few decades. In this period, surface air temperture may change with a rate of several Kelvins per decade. The results obtained with the IAP RAS CM are further interpreted by making use of an energy-balance climate model. As a whole, the results obtained with this simpler model support conclusions made on the basis of the IAP RAS CM simulations.

  16. The effect of phosphogypsum on greenhouse gas emissions during cattle manure composting.

    PubMed

    Hao, Xiying; Larney, Francis J; Chang, Chi; Travis, Greg R; Nichol, Connie K; Bremer, Eric

    2005-01-01

    Phosphogypsum (PG), a by-product of the phosphate fertilizer industry, reduces N losses when added to composting livestock manure, but its impact on greenhouse gas emissions is unclear. The objective of this research was to assess the effects of PG addition on greenhouse gas emissions during cattle feedlot manure composting. Sand was used as a filler material for comparison. The seven treatments were PG10, PG20, PG30, S10, S20, and S30, representing the rate of PG or sand addition at 10, 20, or 30% of manure dry weight and a check treatment (no PG or sand) with three replications. The manure treatments were composted in open windrows and turned five times during a 134-d period. Addition of PG significantly increased electrical conductivity (EC) and decreased pH in the final compost. Total carbon (TC), total nitrogen (TN), and mineral nitrogen contents in the final composted product were not affected by the addition of PG or sand. From 40 to 54% of initial TC was lost during composting, mostly as CO(2), with CH(4) accounting for <14%. The addition of PG significantly reduced CH(4) emissions, which decreased exponentially with the compost total sulfur (TS) content. The emission of N(2)O accounted for <0.2% of initial TN in the manure, increasing as compost pH decreased from alkaline to near neutral. Based on the total greenhouse gas budget, PG addition reduced greenhouse gas emissions (CO(2)-C equivalent) during composting of livestock manure by at least 58%, primarily due to reduced CH(4) emission.

  17. Cost effective determination of vehicle emission factors using on-road measurements

    NASA Astrophysics Data System (ADS)

    Hudda, N.; Fruin, S.; Delfino, R. J.; Sioutas, C.

    2012-07-01

    To evaluate the success of vehicle emissions regulations, trends in both fleet-wide average emissions as well as high-emitter emissions are needed, but it is challenging to capture the full spread of vehicle emission factors (EFs) with chassis dynamometer, tunnel or remote sensing studies. We developed an efficient and cost-effective method using real-time on-road pollutant measurements from a mobile platform, which when linked with real-time traffic data, allows calculating both the average and spread of EFs for light-duty gasoline-powered vehicles (LDV) and heavy-duty diesel-powered vehicles (HDV). This is the first study in California to report EFs under a wide range of real-driving conditions on multiple freeways and it captured much or most of the variability in EFs due to inter-vehicle differences. Fleet average LDV EFs were generally in agreement with most recent studies and an order of magnitude lower than HDV EFs, but over an order of magnitude or more spread was observed for both LDV and HDV EFs. HDV EFs reflected relatively rapid decreases occurring in diesel emissions in Los Angeles/California, and HDV EFs on I-710, a primary route used for goods movement and a focus of additional truck fleet turnover incentives, were lower than on other freeways. When freeway emission rates (ER) were quantified as the product of EF and vehicle activity rates per mile of freeway, ERs were found to be generally similar in magnitude. Despite a two- to three-fold difference in HDV fractions between freeways, higher LDV volumes largely offset this difference.

  18. Nitrogen source and placement effects on soil nitrous oxide emissions from no-till corn.

    PubMed

    Halvorson, Ardell D; Del Grosso, Stephen J

    2012-01-01

    A nitrogen (N) source comparison study was conducted to further evaluate the effects of inorganic N source and placement on growing-season and non-crop period soil nitrous oxide (NO). Commercially available controlled-release N fertilizers were evaluated for their potential to reduce NO emissions from a clay loam soil compared with conventionally used granular urea and urea-ammonium nitrate (UAN) fertilizers in an irrigated no-till (NT) corn ( L.) production system. Controlled-release N fertilizers evaluated were: a polymer-coated urea (ESN), stabilized urea (SuperU), and UAN+AgrotainPlus (SuperU and AgrotainPlus contain nitrification and urease inhibitors). Each N source was surface band applied (202 kg N ha) near the corn row at emergence and watered into the soil the next day. Subsurface banded ESN (ESNssb) and check (no N applied) treatments were included. Nitrous oxide fluxes were measured during two growing seasons and after harvest using static, vented chambers. All N sources had significantly lower growing-season NO emissions than granular urea (0.7% of applied N), with UAN+AgrotainPlus (0.2% of applied N) and ESN (0.3% of applied N) having lower emissions than UAN (0.4% of applied N). Similar trends were observed when expressing NO emissions on a grain yield and N uptake basis. Corn grain yields were not different among N sources but were greater than the check. Selection of N fertilizer source can be a mitigation practice for reducing NO emissions in NT, irrigated corn in semiarid areas. In our study, UAN+AgrotainPlus consistently had the lowest level of NO emissions with no yield loss.

  19. Effects of Passive Fuel-Air Mixing Control on Burner Emissions Via Lobed Fuel Injectors

    NASA Technical Reports Server (NTRS)

    Mitchell, M. G.; Smith, O. I.; Karagozian, A. R.

    1999-01-01

    The present experimental study examines the effects of differing levels of passive fuel-air premixing on flame structures and their associated NO(x) and CO emissions. Four alternative fuel injector geometries were explored, three of which have lobed shapes. These lobed injectors mix fuel and air and strain species inter-faces to differing extents due to streamwise vorticity generation, thus creating different local or core equivalence ratios within flow regions upstream of flame ignition and stabilization. Prior experimental studies of two of these lobed injector flowfields focused on non-reactive mixing characteristics and emissions measurements for the case where air speeds were matched above and below the fuel injector, effectively generating stronger streamwise vorticity than spanwise vorticity. The present studies examine the effects of airstream mismatch (and hence additional spanwise vorticity generation), effects of confinement of the crossflow to reduce the local equivalence ratio, and the effects of altering the geometry and position of the flameholders. NO(x) and CO emissions as well as planar laser-induced fluorescence imaging (PLIF) of seeded acetone are used to characterize injector performance and reactive flow evolution.

  20. Health effects of subchronic exposure to diesel-water-methanol emulsion emission.

    PubMed

    Reed, M D; Blair, L F; Burling, K; Daly, I; Gigliotti, A P; Gudi, R; Mercieca, M D; McDonald, J D; O'Callaghan, J P; Seilkop, S K; Ronskoh, N L; Wagner, V O; Kraska, R C

    2006-03-01

    The U.S. Environmental Protection Agency's National Ambient Air Quality Standards for ozone and particulate matter (PM) require urban non-attainment areas to implement pollution-reduction strategies for anthropogenic source emissions. The type of fuel shown to decrease combustion emissions components versus traditional diesel fuel, is the diesel emulsion. The Lubrizol Corporation, in conjunction with Lovelace Respiratory Research Institute and several subcontracting laboratories, recently conducted a health assessment of the combustion emissions of PuriNOx diesel fuel emulsion (diesel-water-methanol) in rodents. Combustion emissions from either of two, 2002 model Cummins 5.9L ISB engines, were diluted with charcoal-filtered air to exposure concentrations of 125, 250 and 500 microg total PM/m3. The engines were operated on a continuous, repeating, heavy-duty certification cycle (U.S. Code of Federal Regulations, Title 40, Chapter I) using Rotella-T 15W-40 engine oil. Nitrogen oxide (NO) and PM were reduced when engines were operated on PuriNOx versus California Air Resources Board diesel fuel under these conditions. Male and female F344 rats were housed in Hazleton H2000 exposure chambers and exposed to exhaust atmospheres 6 h/day, five days/week for the first 11 weeks and seven days/week thereafter. Exposures ranged from 61 to 73 days depending on the treatment group. Indicators of general toxicity (body weight, organ weight, clinical pathology and histopathology), neurotoxicity (glial fibrillary acidic protein assay), genotoxicity (Ames assay, micronucleus, sister chromatid exchange), and reproduction and development were measured. Overall, effects observed were mild. Emulsion combustion emissions were not associated with neurotoxicity, reproductive/developmental toxicity, or in vivo genotoxicity. Small decreases in serum cholesterol in the 500-microg/m3 exposure group were observed. PM accumulation within alveolar macrophages was evident in all exposure groups

  1. Northern Hemisphere trends in carbon monoxide: effects of changing anthropogenic emissions and biomass burning

    NASA Astrophysics Data System (ADS)

    Novelli, P. C.; Petron, G.; Masarie, K.; Lang, P.; Granier, C.

    2010-12-01

    While the magnitude and direction of changes in tropospheric carbon monoxide (CO) during the past century are still debated; it is most likely that there have been extended periods of increase and decrease, overlaid with much shorter lived changes. The most compelling evidence for a long-term trend in the Northern Hemisphere (NH) comes from a comparison of column measurements determined above the Swiss Alps in the early 1950s and again in the mid-1980s which suggested an increase of ~1% yr-1. Quasi-continuous spectral measurements above Europe and western Russia show increasing column abundances in the 1970s through the mid-1980s, after which CO decreased at a similar rate through the mid-1990s. Several studies have shown declines in NH CO over the past two decades. Carbon monoxide has been measured in air samples collected by the NOAA Cooperative Air Sampling Network since 1988. The results provide a spatial and temporal picture of CO in the marine boundary layer which is used to identify zonal changes. The data suggest a long-term decrease in CO in the NH, with the greatest changes occurring in the 30-90 degree zonal band. Smaller decreases were found in the low Northern and Southern Hemispheres. The primary sources of CO in the NH are roughly evenly distributed between fossil fuel combustion and industrial emissions (FF), oxidation of methane and non-CH4 hydrocarbons, and biomass burning (BB); its major sink is OH. Here we examine how changes in FF and BB emissions have impacted CO in the lower troposphere. A strong decrease in anthropogenic emissions from Annex_1 countries in the early 1990s contributed to a significant decline in its abundance. Continuing declines in their emissions during the late 1990’s and 2000’s added to the downward trend despite increasing emissions from developing nations. The NH decrease in background CO during 1990-2005 (i.e. change determined without effects of the 1998/2003 fires) compares well with FF emissions inventories. Of

  2. Biochar and earthworm effects on soil nitrous oxide and carbon dioxide emissions.

    PubMed

    Augustenborg, Cara A; Hepp, Simone; Kammann, Claudia; Hagan, David; Schmidt, Olaf; Müller, Christoph

    2012-01-01

    Biochar is the product of pyrolysis produced from feedstock of biological origin. Due to its aromatic structure and long residence time, biochar may enable long-term carbon sequestration. At the same time, biochar has the potential to improve soil fertility and reduce greenhouse gas (GHG) emissions from soils. However, the effect of biochar application on GHG fluxes from soil must be investigated before recommendations for field-scale biochar application can be made. A laboratory experiment was designed to measure carbon dioxide (CO) and nitrous oxide (NO) emissions from two Irish soils with the addition of two different biochars, along with endogeic (soil-feeding) earthworms and ammonium sulfate, to assist in the overall evaluation of biochar as a GHG-mitigation tool. A significant reduction in NO emissions was observed from both low and high organic matter soils when biochars were applied at rates of 4% (w/w). Earthworms significantly increased NO fluxes in low and high organic matter soils more than 12.6-fold and 7.8-fold, respectively. The large increase in soil NO emissions in the presence of earthworms was significantly reduced by the addition of both biochars. biochar reduced the large earthworm emissions by 91 and 95% in the low organic matter soil and by 56 and 61% in the high organic matter soil (with and without N fertilization), respectively. With peanut hull biochar, the earthworm emissions reduction was 80 and 70% in the low organic matter soil, and only 20 and 10% in the high organic matter soil (with and without N fertilization), respectively. In high organic matter soil, both biochars reduced CO efflux in the absence of earthworms. However, soil CO efflux increased when peanut hull biochar was applied in the presence of earthworms. This study demonstrated that biochar can potentially reduce earthworm-enhanced soil NO and CO emissions. Hence, biochar application combined with endogeic earthworm activity did not reveal unknown risks for GHG emissions

  3. Health Effects Associated with Inhalation Exposure to Diesel Emission Generated with and without CeO2 Nano Fuel Additive

    EPA Science Inventory

    Diesel exhaust (DE) exposure induces adverse cardiopulmonary effects. Addition of nano cerium (Ce) oxide additive to diesel fuel (DECe) increases fuel burning efficiency resulting in altered emission characteristics and potentially altered health effects. We hypothesized that inh...

  4. Analysis of effect of flameholder characteristics on lean, premixed, partially vaporized fuel-air mixtures quality and nitrogen oxides emissions

    NASA Technical Reports Server (NTRS)

    Cooper, L. P.

    1981-01-01

    An analysis was conducted of the effect of flameholding devices on the precombustion fuel-air characteristics and on oxides of nitrogen (NOx) emissions for combustion of premixed partially vaporized mixtures. The analysis includes the interrelationships of flameholder droplet collection efficiency, reatomization efficiency and blockage, and the initial droplet size distribution and accounts for the contribution of droplet combustion in partially vaporized mixtures to NOx emissions. Application of the analytical procedures is illustrated and parametric predictions of NOx emissions are presented.

  5. Effect of surface tarp on emissions and distribution of drip-applied fumigants.

    PubMed

    Papiernik, Sharon K; Yates, Scott R; Dungan, Robert S; Lesch, Scott M; Zheng, Wei; Guo, Mingxin

    2004-08-15

    Soil fumigants are used to control a wide variety of soil-borne pests in high-cash-value crops. Application of soil fumigants through drip irrigation systems is receiving increasing attention as a method to improve the uniformity of fumigant application. Little information is available on the emissions and soil distribution of fumigants following subsurface drip application, or the effect of plastic tarp on fumigant emissions in these systems. In these experiments, the fumigant compounds 1,3-dichloropropene (1,3-D), Vapam (a methyl isothiocyanate (MITC) precursor), and propargyl bromide (PrBr) were applied to soil beds via drip irrigation at 15 cm depth. Beds were tarped with either standard 1-mil high-density polyethylene (HDPE) or a virtually impermeable film (VIF), leaving the furrows bare. Cumulative emissions of 1,3-D, MITC, and PrBr in these tarped bedded systems was very low, amounting to <10% of the applied mass. These experiments were conducted in the winter months, with average air temperatures of 12-15 degrees C. Cumulative emissions of MITC and 1,3-D from a sandy loam field soil were decreased by > or =80% by tarping the bed with VIF rather than HDPE. A large fraction of the 1,3-D and PrBr flux was from the untarped furrows in VIF-tarped plots, indicating that inhibiting volatilization from the furrow will be important in further reducing emissions in these systems. Monitoring the fumigant distribution in soil indicated that tarping the bed with VIF resulted in a more effective containment of fumigant vapors compared to use of a HDPE tarp.

  6. The effect of fuel sulfur on NH 3 and other emissions from 2000-2001 model year vehicles

    NASA Astrophysics Data System (ADS)

    Durbin, Thomas D.; Pisano, John T.; Younglove, T.; Sauer, Claudia G.; Rhee, Sam H.; Huai, Tao; Miller, J. Wayne; MacKay, Gervase I.; Hochhauser, Albert M.; Ingham, Michael C.; Gorse, Robert A.; Beard, Loren K.; DiCicco, Dominic; Thompson, Neville; Stradling, Richard J.; Rutherford, James A.; Uihlein, James P.

    Atmospheric ammonia (NH 3) is an important precursor to secondary particulate matter formation and information is currently scarce on NH 3 emissions from advanced low-emission vehicles using low-sulfur fuels. With the continuing reduction in the level of sulfur in gasoline, it is important to understand how this change could impact NH 3 emissions, particularly for advanced vehicle technologies. For this study, a total of 12 California-certified low-emission vehicles were tested with a gasoline containing 5, 30, and 150 ppmw sulfur and with both as-received and bench-aged catalysts. Vehicles were tested on each fuel/catalyst configuration over the federal test procedure (FTP) and US06 test cycles. Both regulated and NH 3 emissions were measured in real-time. NH 3 emission rates were generally lower than those of other regulated emissions over the FTP and in the range 14-21 mg mi -1 for the fleet. NH 3 emission rates were approximately five times higher over the more aggressive US06 cycle compared to the FTP. NH 3 emissions were primarily observed during transients, with higher emissions for more aggressive accelerations. Overall, the NH 3 emission factors for the newer technology vehicles tested were lower that than those found in previous studies of older vehicle technologies. Sulfur did not affect NH 3 emissions over the FTP, but higher NH 3 emissions were found for increasing fuel sulfur levels over the US06. Sulfur effects were also observed for nitrogen oxides over the FTP and for all regulated emissions over the US06.

  7. Role of Microwave Radio Emission in Estimation of CMEs Geo-Effectiveness in their Formation Stage

    NASA Astrophysics Data System (ADS)

    Durasova, M.; Fridman, V.; Sheyner, O.

    It was shown by authors earlier [1] that formation stage of the majority CMEs (time interval about 2 hours) is accompanied by sporadic events in solar radio emission. The study of evaluation of CMEs geo-effectiveness is carried out according to their manifestation in microwave emission during formation stage. Data value consists of original recordings of solar radio emission during regular observations in the Radio Astronomical Observatory "Zimenki" (Russia) at 6 frequencies in the range of 9100-100 MHz and includes about 185 events during XXI-XXIII cycles of solar activity. The first stage of study consists in establishment of the fact of CMEs geo- effectiveness on the basis of Kp-index behavior during 1-2 days after CMEs registration. Such parameters of CMES as their Central Locations (CL) and Apparent Widths (AW) were used for analysis. It is shown that the mean AW for geo-effective CMEs top the same one for non-geo-effective CMEs at least by 20%. Above-mentioned study gives stable results for 3 independent volumes of data of 1980-1988, 1998, and 1999. This effect is strengthen for all data concerning geo- effective CMEs of Loop -type and keeps in geometric notions where AW and CL contain the Earth location in space. For further study all radio data are separated into 2 volumes: the first one is connected with sporadic events that are observed during the formation of geo- effective CMEs and the second one - the others CMEs. The difference of characteristics of these sporadic events is examined. It is shown that it is possible to evaluate CMEs geo-effectiveness using totality of characteristics of broad band precursors in radio emission. This work is being supported by the Russian Foundation for Fundamental Research (grant N 00-02-17655).References. 1. Durasova M.S., Fridman V.M., Sheiner O.A. The distinctive features of nonstationary solar radio emission corresponding to CME's formation on the base of wide frequency range observations. In: Proc.of Euroconference

  8. Correlation of acoustic emissions associated with effects from diagnostic and therapeutic ultrasound

    NASA Astrophysics Data System (ADS)

    Samuel, Stanley

    2007-12-01

    This research has investigated the correlation of acoustic emissions with associated contrast-mediated ultrasound bio-effects. The hypothesis that motivated this study was that during exposure with ultrasound, the cavitation occurring in tissue emits acoustical signals, which if correlated with specific bio-effects, could provide a way to monitor the potential bio-effects of exposure. A good bio-effects indicator would find immediate use in research on drug and gene delivery, and could have clinical application in avoiding bio-effects in diagnosis. Studies conducted to test the hypothesis involved investigation of (i) the influence of pulse repetition frequency (PRF) and number of exposures on cell damage, (ii) the effect of total exposure duration and pulse-to-pulse bubble distribution on acoustic emissions and corresponding cell damage, and (iii) the translation of in vitro effects to an in situ environment. Exposures were primarily conducted at a peak rarefactional pressure of 2 MPa, 2.25 MHz insonating frequency and pulse length of 46 cycles. PRFs of 1-, 10-, 100-, 500-, and 1000 Hz were compared. High speed photography (2000 fps) was employed for the investigation of pulse-to-pulse bubble distribution while intravital microscopy was used for in situ studies. A strong correlation was observed between acoustic emissions and bio-effects with the availability of bubbles of resonant size serving as a key link between the two. It was observed that total exposure duration may play an important role in cell damage. Damage increased with increasing total exposure duration from 0 ms to 100 ms with a plateau at above 100 ms. These results were consistent for all studies. There is, therefore, an implication that manipulating these parameters may allow for measurement and control of the extent of bioeffects. Moreover, the correlation of acoustic emission and extravasation observed in in situ studies reveals that cumulative function of the relative integrated power spectrum

  9. Effects of mass airflow rate through an open-circuit gas quantification system when measuring carbon emissions.

    PubMed

    Gunter, Stacey A; Bradford, James A; Moffet, Corey A

    2017-01-01

    Methane (CH) and carbon dioxide (CO) represent 11 and 81%, respectively, of all anthropogenic greenhouse gas emissions. Agricultural CH emissions account for approximately 43% of all anthropogenic CH emissions. Most agricultural CH emissions are attributed to enteric fermentation within ruminant livestock; hence, the heightened interest in quantifying and mitigating this source. The automated, open-circuit gas quantification system (GQS; GreenFeed, C-Lock, Inc., Rapid City, SD) evaluated here can be placed in a pasture with grazing cattle and can measure their CH and CO emissions with spot sampling. However, improper management of the GQS can have an erroneous effect on emission estimates. One factor affecting the quality of emission estimates is the airflow rates through the GQS to ensure a complete capture of the breath cloud emitted by the animal. It is hypothesized that at lower airflow rates this cloud will be incompletely captured. To evaluate the effect of airflow rate through the GQS on emission estimates, a data set was evaluated with 758 CO and CH emission estimates with a range in airflows of 10.7 to 36.6 L/s. When airflow through the GQS was between 26.0 and 36.6 L/s, CO and CH emission estimates were not affected ( = 0.14 and 0.05, respectively). When airflow rates were less than 26.0 L/s, CO and CH emission estimates were lower and decreased as airflow rate decreased ( < 0.0001). We hypothesize that when airflow through the GQS decreases below 26 L/s, breath capture was incomplete and CO and CH emissions are underestimated. Maintaining mass airflow through a GQS at rates greater than 26 L/s is important for producing high quality CO and CH emission estimates.

  10. Hydrogen emissivity in realistic nebulae - The effects of velocity fields and internal dust

    NASA Astrophysics Data System (ADS)

    Cota, S. A.; Ferland, G. J.

    1988-03-01

    The paper presents calculations of the H-beta emissivity expected from nebulae with velocity gradients or internal dust. As has been found by Capriotti, Cox, and Mathews, Lyman line escape and destruction can prevent the 100 percent conversion of high-n Lyman lines into Ly-alpha and Balmer lines. For dusty environments such as the Orion Nebula or the general interstellar medium, the H-beta emissivity can be reduced by less than about 15 percent. Lyman line escape may cause still larger deviations in environments such as nova shells where the expansion velocities are large and velocity gradients likely. Although the partial conversion of Lyman lines only lowers the H-beta emissivity by typically less than about 10 percent under most circumstances, this introduces a systematic error in abundance measurements; the abundance of other elements relative to hydrogen will be overestimated by this amount. This effect must be considered in detail if very accurate abundance measurements are to be made. The present predictions of the deviation from case B emissivity are presented in a way in which they can be easily used by observers or incorporated into photoionization or shock codes.

  11. The effect of electron beams on cyclotron maser emission excited by lower-energy cutoffs

    NASA Astrophysics Data System (ADS)

    Zhao, G. Q.; Feng, H. Q.; Wu, D. J.

    2016-05-01

    Electron-cyclotron maser (ECM) is one of the most important emission mechanisms in astrophysics and can be excited efficiently by lower-energy cutoffs of power-law electrons. These non-thermal electrons probably propagate as a directed collimated beam along ambient magnetic fields. This paper investigates the ECM, in which the effect of electron beams is emphasized. Results show the dependence of emission properties of the ECM on the beam feature. The maximum growth rate of the extraordinary mode (X2) rapidly decreases as the beam momentum increases, while the growth rate of the ordinary mode (O1) changes slightly. In particular, the ordinary mode can overcome the extraordinary mode and becomes the fastest growth mode once the beam momentum is large enough. This research presents an extension of the conventional studies on ECM driven by lower-energy cutoffs and may be helpful to understand better the emission process of solar type I radio bursts, which are dominated by the ordinary mode emission.

  12. Effect of different struvite crystallization methods on gaseous emission and the comprehensive comparison during the composting.

    PubMed

    Jiang, Tao; Ma, Xuguang; Yang, Juan; Tang, Qiong; Yi, Zhigang; Chen, Maoxia; Li, Guoxue

    2016-10-01

    This study compared 4 different struvite crystallization process (SCP) during the composting of pig feces. Four combinations of magnesium and phosphate salts (H3PO4+MgO (PMO), KH2PO4+MgSO4 (KPM), Ca(H2PO4)2+MgSO4 (CaPM), H3PO4+MgSO4 (PMS)) were assessed and were also compared to a control group (CK) without additives. The magnesium and phosphate salts were all supplemented at a level equivalent to 15% of the initial nitrogen content on a molar basis. The SCP significantly reduced NH3 emission by 50.7-81.8%, but not the N2O. Although PMS group had the lowest NH3 emission rate, the PMO treatment had the highest struvite content in the end product. The addition of sulphate decreased CH4 emission by 60.8-74.6%. The CaPM treatment significantly decreased NH3 (59.2%) and CH4 (64.9%) emission and yielded compost that was completely matured. Due to its effective performance and low cost, the CaPM was suggested to be used in practice.

  13. Gaseous emissions in municipal wastes composting: effect of the bulking agent.

    PubMed

    Maulini-Duran, Caterina; Artola, Adriana; Font, Xavier; Sánchez, Antoni

    2014-11-01

    In this study, the emissions of volatile organic compounds (VOC), CH4, N2O and NH3 during composting non-source selected MSW, source selected organic fraction of municipal solid wastes (OFMSW) with wood chips as bulking agent (OF_wood) and source selected OFMSW with polyethylene (PE) tube as bulking agent (OF_tube) and the effect of bulking agent on these emissions have been systematically studied. Emission factors are provided (in kg compound Mg(-1) dry matter): OF_tube (CH4: 0.0185±0.004; N2O: 0.0211±0.005; NH3: 0.612±0.269; VOC: 0.688±0.082) and MSW (CH4: 0.0549±0.0171; N2O: 0.032±0.015; NH3: 1.00±0.20; VOC: 1.05±0.18) present lower values than OF_wood (CH4: 1.27±0.09; N2O: 0.021±0.006; NH3: 4.34±2.79; VOC: 0.989±0.249). A detailed composition of VOC is also presented. Terpenes were the main emitted VOC family in all the wastes studied. Higher emissions of alpha and beta pinene were found during OF_wood composting processes.

  14. Effects of Aftermarket Control Technologies on Gas and Particle Phase Oxidative Potential from Diesel Engine Emissions.

    PubMed

    Pavlovic, Jelica; Holder, Amara L; Yelverton, Tiffany L B

    2015-09-01

    Particulate matter (PM) originating from diesel combustion is a public health concern due to its association with adverse effects on respiratory and cardiovascular diseases and lung cancer. This study investigated emissions from three stationary diesel engines (gensets) and varying power output (230 kW, 400 kW, and 600 kW) at 50% and 90% load to determine concentrations of gaseous (GROS) and PM reactive oxygen species (PMROS). In addition, the influence of three modern emission control technologies on ROS emissions was evaluated: active and passive diesel particulate filters (A-DPF and P-DPF) and a diesel oxidation catalyst (DOC). PMROS made up 30-50% of the total ROS measured without aftermarket controls. All applied controls removed PMROS by more than 75% on average. However, the oxidative potential of PM downstream of these devices was not diminished at the same rate and particles surviving the A-PDF had an even higher oxidative potential on a per PM mass basis compared to the particles emitted by uncontrolled gensets. Further, the GROS as compared to PMROS emissions were not reduced with the same efficiency (<36%). GROS concentrations were highest with the DOC in use, indicating continued formation of GROS with this control. Correlation analyses showed that PMROS and to a lesser extent GROS have a good correlation with semivolatile organic carbon (OC1) subfraction. In addition, results suggest that chemical composition, rather than PM size, is responsible for differences in the PM oxidative potential.

  15. Effect of bulking agents on maturity and gaseous emissions during kitchen waste composting.

    PubMed

    Yang, Fan; Li, Guo Xue; Yang, Qing Yuan; Luo, Wen Hai

    2013-10-01

    This study investigated the effect of bulking agents on the maturity and gaseous emissions of composting kitchen waste. Three different bulking agents (cornstalks, sawdust, and spent mushroom substrate) were used to compost kitchen waste under aerobic conditions in 60-L reactors for a 28-d period. A control treatment was also studied using kitchen waste without a bulking agent. During the experiment, maturity indexes such as temperature, pH value, C/N ratio, and germination index were determined, and continuous measurements of leachate and gaseous emissions (CH₄, N₂O, and NH₃) were taken. The results showed that all of the composts with bulking agents reached the required maturity standard, and the addition of spent mushroom substrate gave the highest maturity (C/N ratio decreased from 23 to 16 and germination index increased from 53% to 111%). The bulking agents also reduced leachate production and CH₄ and N₂O emissions, but had little impact on NH3 emissions. Composting with sawdust as a bulking agent was found to emit less total greenhouse gas (33 kg CO₂-eqt(-1) dry matter) than the other treatments.

  16. Effect of Carex rostrata on seasonal and interannual variability in peatland methane emissions

    NASA Astrophysics Data System (ADS)

    Noyce, Genevieve L.; Varner, Ruth K.; Bubier, Jill L.; Frolking, Steve

    2014-01-01

    are a large natural source of atmospheric methane (CH4), and the sedge Carex rostrata plays a critical role in the production, oxidation, and transport of CH4 in these systems. This 4 year clipping experiment examined the changes in CH4 emissions from a temperate peatland after removing all aboveground C. rostrata biomass. Methane fluxes, dissolved CH4, and environmental variables were measured during spring, summer, and fall from 2008 to 2011. Clipping and removing the C. rostrata leaves and stems caused an immediate decrease in CH4 emissions that persisted over 4 years of this study. There was a strong seasonal trend in CH4 flux, with the largest treatment effects occurring during the fall months when the sedges were senescing. As expected, there was a strong positive correlation between C. rostrata green-leaf area and CH4 flux, implying that the presence of C. rostrata increases CH4 emissions from this peatland. Large interannual variability in vegetation distribution and biomass, water table depth, and temperature was observed in this study, indicating the importance of multiyear studies for understanding the interactions among these factors to determine how they could be incorporated into biogeochemical models to predict CH4 emissions under changing environmental conditions.

  17. Doppler effects on 3-D non-LTE radiation transport and emission spectra.

    SciTech Connect

    Giuliani, J. L.; Davis, J.; DasGupta, A.; Apruzese, John P.; Jennings, Christopher A.; Clark, R. W.; Ampleford, David J.; Bailey, James E.; Thornhill, Joseph W.; Cuneo, Michael Edward; Rochau, Gregory Alan; Coverdale, Christine Anne; Jones, Brent Manley; Hansen, Stephanie B.

    2010-10-01

    Spatially and temporally resolved X-ray emission lines contain information about temperatures, densities, velocities, and the gradients in a plasma. Extracting this information from optically thick lines emitted from complex ions in dynamic, three-dimensional, non-LTE plasmas requires self-consistent accounting for both non-LTE atomic physics and non-local radiative transfer. We present a brief description of a hybrid-structure spectroscopic atomic model coupled to an iterative tabular on-the-spot treatment of radiative transfer that can be applied to plasmas of arbitrary material composition, conditions, and geometries. The effects of Doppler line shifts on the self-consistent radiative transfer within the plasma and the emergent emission and absorption spectra are included in the model. Sample calculations for a two-level atom in a uniform cylindrical plasma are given, showing reasonable agreement with more sophisticated transport models and illustrating the potential complexity - or richness - of radially resolved emission lines from an imploding cylindrical plasma. Also presented is a comparison of modeled L- and K-shell spectra to temporally and radially resolved emission data from a Cu:Ni plasma. Finally, some shortcomings of the model and possible paths for improvement are discussed.

  18. The effects of air pressure on spontaneous otoacoustic emissions of lizards.

    PubMed

    van Dijk, Pim; Manley, Geoffrey A

    2013-06-01

    Small changes of air pressure outside the eardrum of five lizard species led to changes in frequency, level, and peak width of spontaneous otoacoustic emissions (SOAE). In contrast to humans, these changes generally occurred at very small pressures (<20 mbar). As in humans, SOAE amplitudes were generally reduced. Changes of SOAE frequency were both positive and negative, while in humans, they are mostly positive. In addition, in lizards, these effects often showed obvious hysteresis and non-repeatability. The correlation between peak width and height was negative in two species (comparable to humans) and positive in one species. In two other species, no correlation was found. Consequently, a simple oscillator model that explained the negative correlation in humans could not be generally applied to lizards. This presumably reflects the fact that in lizards, the spontaneous otoacoustic emission of sound from the ear consists of a combination of stable oscillations (as in humans), unstable narrow-band oscillations, and broad-band emissions, evident as "plateaus" in emission spectra.

  19. Potential sensitivity of photosynthesis and isoprene emission to direct radiative effects of atmospheric aerosol pollution

    NASA Astrophysics Data System (ADS)

    Strada, S.; Unger, N.

    2015-09-01

    A global Earth system model is applied to quantify the impacts of direct anthropogenic aerosol effective radiative forcing on gross primary productivity (GPP) and isoprene emission. The impacts of different pollution aerosol sources (all anthropogenic, biomass burning and non-biomass burning) are investigated by performing sensitivity experiments. On the global scale, our results show that land carbon fluxes (GPP and isoprene emission) are not sensitive to pollution aerosols, even under a global decline in surface solar radiation (direct + diffuse) by ~ 9 %. At the regional scale, plant productivity (GPP) and isoprene emission show a robust but opposite sensitivity to pollution aerosols, in regions where complex canopies dominate. In eastern North America and Europe, anthropogenic pollution aerosols (mainly from non-biomass burning sources) enhance GPP by +8-12 % on an annual average, with a stronger increase during the growing season (> 12 %). In the Amazon basin and central Africa, biomass burning aerosols increase GPP by +2-5 % on an annual average, with a peak in the Amazon basin during the dry-fire season (+5-8 %). In Europe and China, anthropogenic pollution aerosols drive a decrease in isoprene emission of -2 to -12 % on the annual average. Anthropogenic aerosols affect land carbon fluxes via different mechanisms and we suggest that the dominant mechanism varies across regions: (1) light scattering dominates in the eastern US; (2) cooling in the Amazon basin; and (3) reduction in direct radiation in Europe and China.

  20. Optical properties of metals: Infrared emissivity in the anomalous skin effect spectral region

    SciTech Connect

    Echániz, T.

    2014-09-07

    When the penetration depth of an electromagnetic wave in a metal is similar to the mean free path of the conduction electrons, the Drude classical theory is no longer satisfied and the skin effect becomes anomalous. Physical parameters of this theory for twelve metals were calculated and analyzed. The theory predicts an emissivity peak ε{sub peak} at room temperature in the mid-infrared for smooth surface metals that moves towards larger wavelengths as temperature decreases. Furthermore, the theory states that ε{sub peak} increases with the emission angle but its position, λ{sub peak}, is constant. Copper directional emissivity measurements as well as emissivity obtained using optical constants data confirm the predictions of the theory. Considering the relationship between the specularity parameter p and the sample roughness, it is concluded that p is not the simple parameter it is usually assumed to be. Quantitative comparison between experimental data and theoretical predictions shows that the specularity parameter can be equal to one for roughness values larger than those predicted. An exhaustive analysis of the experimental optical parameters shows signs of a reflectance broad peak in Cu, Al, Au, and Mo around the wavelength predicted by the theory for p = 1.

  1. Quantum cascade emission in the III-nitride material system designed with effective interface grading

    SciTech Connect

    Song, Alex Y. Huang, Tzu-Yung; Zah, Chung-En; Gmachl, Claire F.; Bhat, Rajaram; Wang, Jie; Allerman, Andrew A.

    2015-09-28

    We report the realization of quantum cascade (QC) light emission in the III-nitride material system, designed with effective interface grading (EIG). EIG induces a continuous transition between wells and barriers in the quantum confinement, which alters the eigenstate system and even delocalizes the states with higher energy. Fully transverse-magnetic spontaneous emission is observed from the fabricated III-nitride QC structure, with a center wavelength of ∼4.9 μm and a full width at half maximum of ∼110 meV, both in excellent agreement with theoretical predictions. A multi-peak photo-response spectrum is also measured from the QC structure, which again agrees well with theoretical calculations and verifies the effects of EIG.

  2. Effect of amplified spontaneous emission on selectivity of laser photoionisation of the 177Lu radioisotope

    NASA Astrophysics Data System (ADS)

    D'yachkov, A. B.; Gorkunov, A. A.; Labozin, A. V.; Mironov, S. M.; Panchenko, V. Ya; Firsov, V. A.; Tsvetkov, G. O.

    2016-06-01

    A significant deselecting effect of amplified spontaneous emission has been observed in the experiments on selective laser photoionisation of the 177Lu radioisotope according to the scheme 5d6s2 2D3/2 → 5d6s6p 4Fo5/2 (18505 cm-1) → 5d6s7s 4D3/2(37194 cm-1) → autoionisation state (53375 cm-1). The effect is conditioned by involvement of non-target isotopes from the lower metastable level 5d6s2 2D5/2(1994 cm-1) into the ionisation process. Spectral filtering of spontaneous emission has allowed us to significantly increase the selectivity of the photoionisation process of the radioisotope and to attain a selectivity value of 105 when using saturating light intensities.

  3. 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

  4. Interference effects in electron emission from H{sub 2} by 68-MeV/u Kr{sup 33+} impact: Dependence on the emission angle

    SciTech Connect

    Stolterfoht, N.; Skogvall, B.; Sulik, B.; Gulyas, L.; Chesnel, J.Y.; Fremont, F.; Hennecart, D.; Cassimi, A.; Adoui, L.; Hossain, S.; Tanis, J.A.

    2003-03-01

    Angle- and energy-dependent cross sections for electron emission were measured for 68-MeV/u Kr{sup 33+} ions impacting on H{sub 2}. These results show, in accordance with our earlier observation, that interference effects are produced by the coherent emission of electrons from the two H atoms, in analogy with Young's two-slit experiment. Furthermore, the present results demonstrate that the observed oscillatory pattern varies with the electron observation angle, contrary to our earlier expectations but in agreement with recent theoretical predictions.

  5. Cost-effectiveness of feeding strategies to reduce greenhouse gas emissions from dairy farming.

    PubMed

    Van Middelaar, C E; Dijkstra, J; Berentsen, P B M; De Boer, I J M

    2014-01-01

    The objective of this paper was to evaluate the cost-effectiveness of 3 feeding strategies to reduce enteric CH4 production in dairy cows by calculating the effect on labor income at the farm level and on greenhouse gas (GHG) emissions at the chain level (i.e., from production of farm inputs to the farm gate). Strategies included were (1) dietary supplementation of an extruded linseed product (56% linseed; 1kg/cow per day in summer and 2kg/cow per day in winter), (2) dietary supplementation of a nitrate source (75% nitrate; 1% of dry matter intake), and (3) reducing the maturity stage of grass and grass silage (grazing at 1,400 instead of 1,700kg of dry matter/ha and harvesting at 3,000 instead of 3,500kg of dry matter/ha). A dairy farm linear programing model was used to define an average Dutch dairy farm on sandy soil without a predefined feeding strategy (reference situation). Subsequently, 1 of the 3 feeding strategies was implemented and the model was optimized again to determine the new economically optimal farm situation. Enteric CH4 production in the reference situation and after implementing the strategies was calculated based on a mechanistic model for enteric CH4 and empirical formulas explaining the effect of fat and nitrate supplementation on enteric CH4 production. Other GHG emissions along the chain were calculated using life cycle assessment. Total GHG emissions in the reference situation added up to 840kg of CO2 equivalents (CO2e) per t of fat- and protein-corrected milk (FPCM) and yearly labor income of €42,605. Supplementation of the extruded linseed product reduced emissions by 9kg of CO2e/t of FPCM and labor income by €16,041; supplementation of the dietary nitrate source reduced emissions by 32kg of CO2e/t of FPCM and labor income by €5,463; reducing the maturity stage of grass and grass silage reduced emissions by 11kg of CO2e/t of FPCM and labor income by €463. Of the 3 strategies, reducing grass maturity was the most cost-effective

  6. GENERAL: Steady State Entanglement and Saturation Effects in Correlated Spontaneous Emission Lasers

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Hu, Xiang-Ming; Shi, Wen-Xing

    2009-08-01

    It has recently been shown that correlated spontaneous emission lasers (CEL) exhibit transient entanglement in the linear regime. Here we re-examine the quantum correlations in two-photon CEL and explore the saturation effects on continuous variable entanglement. It is shown that the steady state entanglement is obtainable in the weak or moderate saturation regime, while is washed out in the deep saturation regime.

  7. Conical emission from laser filaments and higher-order Kerr effect in air.

    PubMed

    Béjot, P; Kasparian, J

    2011-12-15

    We numerically investigate the conical emission (CE) from ultrashort laser filaments, both considering and disregarding the higher-order Kerr effect (HOKE). While the consideration of HOKE has almost no influence on the predicted CE from collimated beams, differences arise for tightly focused beams. This difference is attributed to the different relative contributions of the nonlinear focus and of the modulational instability over the whole filament length.

  8. Long-Term Formaldehyde Emissions from Medium-Density Fiberboard in a Full-Scale Experimental Room: Emission Characteristics and the Effects of Temperature and Humidity.

    PubMed

    Liang, Weihui; Yang, Shen; Yang, Xudong

    2015-09-01

    We studied formaldehyde emissions from the medium-density fiberboard (MDF) in a full-scale experimental room to approximate emissions in actual buildings. Detailed indoor formaldehyde concentrations and temperature and humidity data were obtained for about 29 months. Temperature, relative humidity (RH), and absolute humidity (AH) ranged over -10.9-31.4 °C, 46.5-83.6%, and 1.1-23.1 g/kgair, respectively. Annual cyclical seasonal variations were observed for indoor formaldehyde concentrations and emission rates, exhibiting entirely different characteristics than those in an environmental chamber under constant environmental conditions. The maximum concentration occurred in summer rather than at initial introduction of the material. The concentrations in summer could be a few up to 20 times higher than that in winter, depending on the indoor temperature and humidity conditions. Concentrations decreased by 20-65% in corresponding months of the second year. Indoor formaldehyde concentrations were positively correlated with temperature and AH but were poorly correlated with RH. The combined effects of temperature and AH on formaldehyde emissions from MDF in actual buildings were verified. These detailed long-term experimental results could be used with environmental chamber measurement data to scale up and validate emission models from chambers held at constant conditions to actual buildings.

  9. Emission-Line Properties and Selection Effects for z > 4 Quasars

    NASA Astrophysics Data System (ADS)

    Constantin, A.; Shields, J. C.; Hamann, F.

    2000-12-01

    A growing number of QSOs are now known to exist at redshifts beyond 4, and these sources provide important opportunities for better understanding of the astrophysics of galaxy formation and evolution. To date there are ~ 130 known QSOs with z > 4, but only limited efforts have been made to survey systematically the emission-line properties of these objects and/or the selection effects related with the techniques by which they were discovered. In this poster we will present results of a program of high signal-to-noise spectroscopy for 44 QSOs using the MMT and Keck observatories. The majority of these sources were originally identified via color selection techiques. The quasar spectra cover wavelengths between 1100 Å and 1700 Å in the rest frame, for sources spanning a luminosity range of ~ 2 orders of magnitude. An examination of the luminosity dependence of the emission features reveals evidence for a weak Baldwin effect. Spectrum composites for the whole data set and for subsets are obtained and analysed in order to investigate the spectral dependence on selection effects. The results show a tendency for stronger C IV emission lines for color-selected quasars, than for grism-selected objects.

  10. Interactive effects of environmental change and management strategies on regional forest carbon emissions.

    PubMed

    Hudiburg, Tara W; Luyssaert, Sebastiaan; Thornton, Peter E; Law, Beverly E

    2013-11-19

    Climate mitigation activities in forests need to be quantified in terms of the long-term effects on forest carbon stocks, accumulation, and emissions. The impacts of future environmental change and bioenergy harvests on regional forest carbon storage have not been quantified. We conducted a comprehensive modeling study and life-cycle assessment of the impacts of projected changes in climate, CO2 concentration, and N deposition, and region-wide forest management policies on regional forest carbon fluxes. By 2100, if current management strategies continue, then the warming and CO2 fertilization effect in the given projections result in a 32-68% increase in net carbon uptake, overshadowing increased carbon emissions from projected increases in fire activity and other forest disturbance factors. To test the response to new harvesting strategies, repeated thinnings were applied in areas susceptible to fire to reduce mortality, and two clear-cut rotations were applied in productive forests to provide biomass for wood products and bioenergy. The management strategies examined here lead to long-term increased carbon emissions over current harvesting practices, although semiarid regions contribute little to the increase. The harvest rates were unsustainable. This comprehensive approach could serve as a foundation for regional place-based assessments of management effects on future carbon sequestration by forests in other locations.

  11. U.S. regional greenhouse gas emissions analysis comparing highly resolved vehicle miles traveled and CO2 emissions: mitigation implications and their effect on atmospheric measurements

    NASA Astrophysics Data System (ADS)

    Mendoza, D. L.; Gurney, K. R.

    2010-12-01

    Carbon dioxide (CO2) is the most abundant anthropogenic greenhouse gas and projections of fossil fuel energy demand show CO2 concentrations increasing indefinitely into the future. After electricity production, the transportation sector is the second largest CO2 emitting economic sector in the United States, accounting for 32.3% of the total U.S. emissions in 2002. Over 80% of the transport sector is composed of onroad emissions, with the remainder shared by the nonroad, aircraft, railroad, and commercial marine vessel transportation. In order to construct effective mitigation policy for the onroad transportation sector and more accurately predict CO2 emissions for use in transport models and atmospheric measurements, analysis must incorporate the three components that determine the CO2 onroad transport emissions: vehicle fleet composition, average speed of travel, and emissions regulation strategies. Studies to date, however, have either focused on one of these three components, have been only completed at the national scale, or have not explicitly represented CO2 emissions instead relying on the use of vehicle miles traveled (VMT) as an emissions proxy. National-level projections of VMT growth is not sufficient to highlight regional differences in CO2 emissions growth due to the heterogeneity of vehicle fleet and each state’s road network which determines the speed of travel of vehicles. We examine how an analysis based on direct CO2 emissions and an analysis based on VMT differ in terms of their emissions and mitigation implications highlighting potential biases introduced by the VMT-based approach. This analysis is performed at the US state level and results are disaggregated by road and vehicle classification. We utilize the results of the Vulcan fossil fuel CO2 emissions inventory which quantified emissions for the year 2002 across all economic sectors in the US at high resolution. We perform this comparison by fuel type,12 road types, and 12 vehicle types

  12. Effects of manure and water applications on 1,3-dichloropropene and chloropicrin emissions in a field trial.

    PubMed

    Gao, Suduan; Qin, Ruijun; Hanson, Bradley D; Tharayil, Nishanth; Trout, Thomas J; Wang, Dong; Gerik, James

    2009-06-24

    Minimizing fumigant emissions is required for meeting air-quality standards. Application of organic materials to surface soil has been effective in reducing fumigant emissions during laboratory tests, but the potential to reduce emissions in the field has not been adequately evaluated. The objective of this study was to determine the effect of incorporated composted manure with or without water applications on fumigant emissions and the potential impact on pest control efficacy under field conditions. Treatments included a bare-soil control, composted dairy manure at 12.4 and 24.7 Mg ha(-1), postfumigation intermittent water seals (11 mm water irrigated immediately following fumigation and 4 mm at 12, 24, and 48 h), and incorporation of manure at 12.4 Mg ha(-1) combined with the water seals or a high-density polyethylene (HDPE) tarp. Telone C35 was shank-applied at 553 kg ha(-1), and emissions of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) were monitored for 10 days. The results indicate that there was no significant difference in emission peak flux and cumulative emission loss between the control and the 12.4 Mg ha(-1) manure treatment. The higher manure rate (24.7 Mg ha(-1)) resulted in lower emission flux and cumulative emission loss than 12.4 Mg ha(-1), although the differences were only significant for CP. In contrast, the water treatments with or without manure incorporation significantly reduced peak emission rates (80% reduction) and cumulative emission loss ( approximately 50% reduction). The manure + HDPE treatment resulted in the lowest CP emissions but slightly higher 1,3-D emissions than the water treatments. Reductions in peak emission from water treatments can be important in reducing the potential acute exposure risks to workers and bystanders. This research demonstrated that incorporation of composted manure alone did not reduce fumigant emissions and effective emission reduction with manure amendment may require higher application rates and

  13. Emission Characteristics and Effect of Battery Drain in "Budget" Curing Lights.

    PubMed

    AlShaafi, M M; Harlow, J E; Price, H L; Rueggeberg, F A; Labrie, D; AlQahtani, M Q; Price, R B

    2016-01-01

    Recently, "budget" dental light-emitting diode (LED)-based light-curing units (LCUs) have become available over the Internet. These LCUs claim equal features and performance compared to LCUs from major manufacturers, but at a lower cost. This study examined radiant power, spectral emission, beam irradiance profiles, effective emission ratios, and the ability of LCUs to provide sustained output values during the lifetime of a single, fully charged battery. Three examples of each budget LCU were purchased over the Internet (KY-L029A and KY-L036A, Foshan Keyuan Medical Equipment Co, and the Woodpecker LED.B, Guilin Woodpecker Medical Instrument Co). Major dental manufacturers provided three models: Elipar S10 and Paradigm (3M ESPE) and the Bluephase G2 (Ivoclar Vivadent). Radiant power emissions were measured using a laboratory-grade thermopile system, and the spectral emission was captured using a spectroradiometer system. Irradiance profiles at the tip end were measured using a modified laser beam profiler, and the proportion of optical tip area that delivered in excess of 400 mW/cm(2) (termed the effective emission ratio) was displayed using calibrated beam profile images. Emitted power was monitored over sequential exposures from each LCU starting at a fully charged battery state. The results indicated that there was less than a 100-mW/cm(2) difference between manufacturer-stated average tip end irradiance and the measured output. All the budget lights had smaller optical tip areas, and two demonstrated lower effective emission ratios than did the units from the major manufacturers. The budget lights showed discontinuous values of irradiance over their tip ends. One unit delivered extremely high output levels near the center of the light tip. Two of the budget lights were unable to maintain sustained and stable light output as the battery charge decreased with use, whereas those lights from the major manufacturers all provided a sustained light output for at least

  14. Continuous measurements of CO2 emission from cultivated peat soil - effect of tillage intensity

    NASA Astrophysics Data System (ADS)

    Berglund, Örjan; Berglund, Kerstin

    2014-05-01

    Peatlands process and transfer significant quantities of greenhouse gases (GHG) such as CO2, CH4 and N2O. Most natural water-saturated peatlands sequester large amounts of CO2 from the atmosphere and emit CH4. Drainage and cultivation of peat soils increase soil aeration and reverse the carbon flux into net CO2 emissions, while CH4 emissions decrease and cultivated peat soils may even act as sinks for CH4. Fertile peat soils are potential sources of N2O when drained. In this investigation we used automatic dark chambers (ADC BioScientific Ltd) to measure CO2 emissions from plots with different soil tillage intensities. The field trial is located on the island Gotland east of the Swedish main land (57.584825N 18.47691E) and the soil is a peat soil with high pH (7.5) and organic content of 46.4 % (loss on ignition). The set-up was 4 treatments repeated in 4 blocks. Each plot was 18 by 25 meters and the following treatments were tested: A. Ploughing every year B. Ploughing 1 out of 4 years C. Only stubble cultivation D. Permanent ley One chamber was put in each plot and connected to a master control unit to create a network with 16 chambers. Measurements were made every hour during most of 2012 (17/4- 6/11 with some gaps) and every second hour during 2013 (22/4-27/6). Higher emissions could be observed just after cultivation and that effect lasted for about one day. The average emission was highest from treatment D during 2012 (4.53 μmol m-2 s-1) and treatment C and D during 2013 (3.85 μmol m-2 s-1).

  15. Effect of fertilising with pig slurry and chicken manure on GHG emissions from Mediterranean paddies.

    PubMed

    Maris, S C; Teira-Esmatges, M R; Bosch-Serra, A D; Moreno-García, B; Català, M M

    2016-11-01

    Soil fertilisation affects greenhouse gas emissions. The objective of this study was to compare the effect of different fertilisation strategies on N2O, CH4 emissions and on ecosystem respiration (CO2 emissions), during different periods of rice cultivation (rice crop, postharvest period, and seedling) under Mediterranean climate. Emissions were quantified weekly by the photoacoustic technique at two sites. At Site 1 (2011 and 2012), background treatments were 2 doses of chicken manure (CM): 90 and 170kgNH4(+)-Nha(-1) (CM-90, CM-170), urea (U, 150kgNha(-1)) and no-N (control). Fifty kilogram N ha(-1) ammonium sulphate (AS) were topdress applied to all of them. At Site 2 (2012), background treatments were 2 doses of pig slurry (PS): 91 and 152kgNH4(+)-Nha(-1) (PS-91, PS-152) and ammonium sulphate (AS) at 120kgNH4(+)-Nha(-1) and no-N (control). Sixty kilogram NH4(+)-Nha(-1) as AS were topdress applied to AS and PS-91. During seedling, global warming potential (GWP) was ~3.5-17% of that of the whole rice crop for the CM treatments. The postharvest period was a net sink for CH4, and CO2 emissions only increased for the CM-170 treatment (up to 2MgCO2ha(-1)). The GWP of the entire rice crop reached 17Mg CO2-eqha(-1) for U, and was 14 for CM-170, and 37 for CM-90. The application of PS at agronomic doses (~170kgNha(-1)) allowed high yields (~7.4Mgha(-1)), the control of GWP (~6.5MgCO2-eqha(-1)), and a 13% reduction in greenhouse gas intensity (GHGI) to 0.89kgCO2-eqkg(-1) when compared to AS (1.02kgCO2-eqkg(-1)).

  16. Did policies to abate atmospheric emissions from traffic have a positive effect in London?

    PubMed

    Font, Anna; Fuller, Gary W

    2016-11-01

    A large number of policy initiatives are being taken at the European level, across the United Kingdom and in London to improve air quality and reduce population exposure to harmful pollutants from traffic emissions. Trends in roadside increments of nitrogen oxides (NOX), nitrogen dioxide (NO2), particulate matter (PM), black carbon (CBLK) and carbon dioxide (CO2) were examined at 65 London monitoring sites for two periods of time: 2005-2009 and 2010-2014. Between 2005 and 2009 there was an overall increase in NO2 reflecting the growing evidence of real world emissions from diesel vehicles. Conversely, NO2 decreased by 10%·year(-1) from 2010 onwards along with PM2.5 (-28%·year(-1)) and black carbon (-11%·year(-1)). Downwards trends in air pollutants were not fully explained by changes in traffic counts therefore traffic exhaust emission abatement policies were proved to be successful in some locations. PM10 concentrations showed no significant overall change suggesting an increase in coarse particles which offset the decrease in tailpipe emissions; this was especially the case on roads in outer London where an increase in the number of Heavy Good Vehicles (HGVs) was seen. The majority of roads with increasing NOX experienced an increase in buses and coaches. Changes in CO2 from 2010 onwards did not match the downward predictions from reduced traffic flows and improved fleet efficiency. CO2 increased along with increasing HGVs and buses. Polices to manage air pollution provided differential benefits across London's road network. To investigate this, k-means clustering technique was applied to group roads which behaved similarly in terms of trends to evaluate the effectiveness of policies to mitigate traffic emissions. This is the first time that London's roadside monitoring sites have been considered as a population rather than summarized as a mean behaviour only, allowing greater insight into the differential changes in air pollution abatement policies.

  17. Effect of ethanol-gasoline blends on small engine generator energy efficiency and exhaust emission.

    PubMed

    Lin, Wen-Yinn; Chang, Yuan-Yi; Hsieh, You-Ru

    2010-02-01

    This study was focused on fuel energy efficiency and pollution analysis of different ratios of ethanol-gasoline blended fuels (E0, E3, E6, and E9) under different loadings. In this research, the experimental system consisted of a small engine generator, a particulate matter measurement system, and an exhaust gas analyzer system. Different fuels, unleaded gasoline, and ethanol-gasoline blends (E0, E3, E6, and E9) were used to study their effects on the exhaust gas emission and were expressed as thermal efficiency of the small engine generator energy efficiency. The results suggested that particle number concentration increased as the engine loading increased; however, it decreased as the ethanol content in the blend increased. While using E6 as fuel, the carbon monoxide (CO) concentration was less than other fuels (E0, E3, and E9) for each engine loading. The average of CO concentration reduction by using E3, E6, and E9 is 42, 86, and 83%, respectively. Using an ethanol-gasoline blend led to a significant reduction in exhaust emissions by approximately 78.7, 97.5, and 89.46% of the mean average values of hydrocarbons (HCs) with E3, E6, and E9 fuels, respectively, for all engine loadings. Using an ethanol-gasoline blend led to a significant reduction in exhaust emissions by approximately 35, 86, and 77% of the mean average values of nitrogen oxides (NOx) with E3, E6, and E9 fuels, respectively, at each engine loading. The E6 fuel gave the best results of the exhaust emissions, and the E9 fuel gave the best results of the particle emissions and engine performance. The thermal efficiency of the small engine generator increased as the ethanol content in the blend increased and as the engine loading increased.

  18. Effect of VOC emissions from vegetation on urban air quality during hot periods

    NASA Astrophysics Data System (ADS)

    Churkina, Galina; Kuik, Friderike; Bonn, Boris; Lauer, Axel; Grote, Ruediger; Butler, Tim

    2016-04-01

    Programs to plant millions of trees in cities around the world aim at the reduction of summer temperatures, increase of carbon storage, storm water control, and recreational space, as well as at poverty alleviation. These urban greening programs, however, do not take into account how closely human and natural systems are coupled in urban areas. Compared with the surroundings of cities, elevated temperatures together with high anthropogenic emissions of air and water pollutants are quite typical in urban systems. Urban and sub-urban vegetation respond to changes in meteorology and air quality and can react to pollutants. Neglecting this coupling may lead to unforeseen negative effects on air quality resulting from urban greening programs. The potential of emissions of volatile organic compounds (VOC) from vegetation combined with anthropogenic emissions of air pollutants to produce ozone has long been recognized. This ozone formation potential increases under rising temperatures. Here we investigate how emissions of VOC from urban vegetation affect corresponding ground-level ozone and PM10 concentrations in summer and especially during heat wave periods. We use the Weather Research and Forecasting Model with coupled atmospheric chemistry (WRF-CHEM) to quantify these feedbacks in the Berlin-Brandenburg region, Germany during the two summers of 2006 (heat wave) and 2014 (reference period). VOC emissions from vegetation are calculated by MEGAN 2.0 coupled online with WRF-CHEM. Our preliminary results indicate that the contribution of VOCs from vegetation to ozone formation may increase by more than twofold during heat wave periods. We highlight the importance of the vegetation for urban areas in the context of a changing climate and discuss potential tradeoffs of urban greening programs.

  19. Simulating and Analyzing Long-Term Changes in Emissions, Air Quality, Aerosol Feedback Effects and Human Health

    EPA Science Inventory

    This presentation covers work performed by the authors to characterize changes in emissions over the 1990 – 2010 time period, quantify the effects of these emission changes on air quality and aerosol/radiation feedbacks using both observations and model simulations, and fin...

  20. The Effects of Abiotic Factors on Induced Volatile Emissions in Corn Plants1

    PubMed Central

    Gouinguené, Sandrine P.; Turlings, Ted C.J.

    2002-01-01

    Many plants respond to herbivory by releasing a specific blend of volatiles that is attractive to natural enemies of the herbivores. In corn (Zea mays), this induced odor blend is mainly composed of terpenoids and indole. The induced signal varies with plant species and genotype, but little is known about the variation due to abiotic factors. Here, we tested the effect of soil humidity, air humidity, temperature, light, and fertilization rate on the emission of induced volatiles in young corn plants. Each factor was tested separately under constant conditions for the other factors. Plants released more when standing in dry soil than in wet soil, whereas for air humidity, the optimal release was found at around 60% relative humidity. Temperatures between 22°C and 27°C led to a higher emission than lower or higher temperatures. Light intensity had a dramatic effect. The emission of volatiles did not occur in the dark and increased steadily with an increase in the light intensity. An experiment with an unnatural light-dark cycle showed that the release was fully photophase dependent. Fertilization also had a strong positive effect; the emission of volatiles was minimal when plants were grown under low nutrition, even when results were corrected for plant biomass. Changes in all abiotic factors caused small but significant changes in the relative ratios among the different compounds (quality) in the induced odor blends, except for air humidity. Hence, climatic conditions and nutrient availability can be important factors in determining the intensity and variability in the release of induced plant volatiles. PMID:12114583

  1. 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

  2. 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.

  3. Soil greenhouse gas emissions reduce the contribution of mangrove plants to the atmospheric cooling effect

    NASA Astrophysics Data System (ADS)

    Chen, Guangcheng; Chen, Bin; Yu, Dan; Tam, Nora F. Y.; Ye, Yong; Chen, Shunyang

    2016-12-01

    Mangrove soils have been recognized as sources of greenhouse gases, but the atmospheric fluxes are poorly characterized, and their adverse warming effect has rarely been considered with respect to the potential contribution of mangrove wetlands to climate change mitigation. The current study balanced the warming effect of soil greenhouse gas emissions with the plant carbon dioxide (CO2) sequestration rate derived from the plants’ net primary production in a productive mangrove wetland in South China to assess the role of mangrove wetlands in reducing the atmospheric warming effect. Soil characteristics were also studied in the summer to examine their relationships with gas fluxes. The soil to atmosphere fluxes of nitrous oxide (N2O), methane (CH4) and CO2 ranged from -1.6 to 50.0 μg m-2 h-1, from -1.4 to 5360.1 μg m-2 h-1 and from -31 to 512 mg m-2 h-1, respectively, which indicated that the mangrove soils act as sources of greenhouse gases in this area. The gas fluxes were higher in summer than in the cold seasons and were variable across mangrove sites. Gas fluxes in summer were positively correlated with the soil organic carbon, total nitrogen, and ammonia contents. The mangrove plants sequestered a considerable amount of atmospheric CO2 at rates varying from 3652 to 7420 g CO2 m-2 yr-1. The ecosystem acted as a source of CH4 and N2O gases but was a more intense CO2 sink. However, the warming effect of soil gas emissions accounted for 9.3-32.7% of the plant CO2 sequestration rate, partially reducing the benefit of mangrove plants, and the two trace gases comprised 9.7-33.2% of the total warming effect. We therefore propose that an assessment of the reduction of atmospheric warming effects by a mangrove ecosystem should consider both soil greenhouse gas emissions and plant CO2 sequestration.

  4. Carbon dioxide emissions from Deccan volcanism and a K/T boundary greenhouse effect

    NASA Astrophysics Data System (ADS)

    Caldeira, Ken; Rampino, Michael R.

    1990-08-01

    A greenhouse warming caused by increased emissions of carbon dioxide from the Deccan Traps volcanism has been suggested as the cause of the terminal Cretaceous extinctions on land and in the sea. Total eruptive and noneruptive CO2 output by the Deccan eruptions (from 6 to 20 x 10 to the 16th moles) over a period of several hundred thousand years is estimated based on best estimates of the CO2 weight fraction of the original basalts and basaltic melts, the fraction of CO2 degassed, and the volume of the Deccan Traps eruptions. Results of a model designed to estimate the effects of increased CO2 on climate and ocean chemistry suggest that increases in atmospheric pCO2 due to Deccan Traps CO2 emissions would have been less than 75 ppm, leading to a predicted global warming of less than 1 C over several hundred thousand years. It is concluded that the direct climate effects of CO2 emissions from the Deccan eruptions would have been too weak to be an important factor in the end-Cretaceous mass extinctions.

  5. Elementary framework for cold field emission: Incorporation of quantum-confinement effects

    SciTech Connect

    Patterson, A. A. Akinwande, A. I.

    2013-12-21

    Although the Fowler-Nordheim (FN) equation serves as the foundation of cold field emission theory, it may not be suitable for predicting the emitted current density (ECD) from emitters with a quantum-confined electron supply. This work presents an analytical framework for treating cold field emission from metals that includes the effects of a quantum-confined electron supply. Within the framework, quantum confinement in emitters is classified into transverse and normal quantum confinement based on the orientation of the confinement relative to the emission direction. The framework is used to generate equations predicting the ECD from rectangular and cylindrical emitter geometries comprised of electron supplies of reduced dimensionality. Transverse quantum confinement of the electron supply leads to a reduction in the total ECD as transverse emitter dimensions decrease and normal quantum confinement results in an oscillatory ECD as a function of the normal quantum well width. Incorporating a geometry-dependent field enhancement factor into the model reveals an optimal transverse well width for which quantum confinement of the electron supply and field enhancement equally affect the ECD and a maximum total ECD for the emitter geometry at a given applied field is obtained. As a result, the FN equation over-predicts the ECD from emitters with transverse dimensions under approximately 5 nm, and in those cases, geometry-specific ECD equations incorporating quantum-confinement effects should be employed instead.

  6. Can Water-Injected Turbomachines Provide Cost-Effective Emissions and Maintenance Reductions?

    NASA Technical Reports Server (NTRS)

    Hendricks, Robert C.; Daggett, David L.; Shouse, Dale T.; Roquemore, William M.; Brankovic, Andreja; Ryder, Robert C., Jr.

    2011-01-01

    An investigation has been performed to evaluate the effect of water injection on the performance of the Air Force Research Laboratory (AFRL, Wright-Patterson Air Force Base (WPAFB)) experimental trapped vortex combustor (TVC) over a range of fuel-to-air and water-to-fuel ratios. Performance is characterized by combustor exit quantities: temperature and emissions measurements using rakes, and overall pressure drop, from upstream plenum to combustor exit. Combustor visualization is performed using gray-scale and color still photographs and high-frame-rate videos. A parallel investigation evaluated the performance of a computational fluid dynamics (CFD) tool for the prediction of the reacting flow in a liquid fueled combustor (e.g., TVC) that uses water injection for control of pollutant emissions and turbine inlet temperature. Generally, reasonable agreement is found between data and NO(x) computations. Based on a study assessing the feasibility and performance impact of using water injection on a Boeing 747-400 aircraft to reduce NO(x) emissions during takeoff, retrofitting does not appear to be cost effective; however, an operator of a newly designed engine and airframe might be able to save up to 1.0 percent in operating costs. Other challenges of water injection will be discussed.

  7. Topographic Effects on the Surface Emissivity of a Mountainous Area Observed by a Spaceborne Microwave Radiometer.

    PubMed

    Pulvirenti, Luca; Pierdicca, Nazzareno; Marzano, Frank S

    2008-03-03

    A simulation study to understand the influence of topography on the surfaceemissivity observed by a satellite microwave radiometer is carried out. We analyze theeffects due to changes in observation angle, including the rotation of the polarization plane.A mountainous area in the Alps (Northern Italy) is considered and the information on therelief extracted from a digital elevation model is exploited. The numerical simulation refersto a radiometric image, acquired by a conically-scanning radiometer similar to AMSR-E,i.e., flying at 705 km of altitude with an observation angle of 55°. To single out the impacton surface emissivity, scattering of the radiation due to the atmosphere or neighboringelevated surfaces is not considered. C and X bands, for which atmospheric effects arenegligible, and Ka band are analyzed. The results indicate that the changes in the localobservation angle tend to lower the apparent emissivity of a radiometric pixel with respectto the corresponding flat surface characteristics. The effect of the rotation of thepolarization plane enlarges (vertical polarization), or attenuates (horizontal polarization)this decrease. By doing some simplifying assumptions for the radiometer antenna, theconclusion is that the microwave emissivity at vertical polarization is underestimated,whilst the opposite occurs for horizontal polarization, except for Ka band, for which bothunder- and overprediction may occur. A quantification of the differences with respect to aflat soil and an approximate evaluation of their impact on soil moisture retrieval areyielded.

  8. Understanding the side effects of emission trading: implications for waste management.

    PubMed

    Braschel, Nina; Posch, Alfred; Pierer, Magdalena

    2014-01-01

    The trading of emission allowances is an important market instrument in climate policy. However, the inclusion of certain branches of industry in the trading system not only provides incentives for emission reduction, it also entails unwanted side effects. Thus, the objective of the present study is to identify such side effects-positive and negative-by examining the potential impact of waste management inclusion in the European Union Emissions Trading Scheme (EU ETS). Desk research was supplemented with qualitative and quantitative empirical analysis (based on expert interviews and a questionnaire) in order to analyse the related perceptions and expectations of actors and stakeholders. The impact of waste management inclusion in the EU ETS is analysed in terms of the following three areas: (i) costs and cost pass-through, (ii), competitiveness and market position, and (iii) carbon leakage. Concerning expectations in the area of costs, both the interviewed experts and the practitioners surveyed thought that costs were likely to increase or that they could be passed on to customers. However, experts and practitioners differed with respect to the possibility of carbon leakage. Clearly, increased knowledge of the possible impact arising from inclusion of the waste sector in the EU ETS would enable managers to become more proactive and to manage waste streams and treatment options more economically.

  9. Carbon dioxide emissions from Deccan volcanism and a K/T boundary greenhouse effect

    NASA Technical Reports Server (NTRS)

    Caldeira, Ken; Rampino, Michael R.

    1990-01-01

    A greenhouse warming caused by increased emissions of carbon dioxide from the Deccan Traps volcanism has been suggested as the cause of the terminal Cretaceous extinctions on land and in the sea. Total eruptive and noneruptive CO2 output by the Deccan eruptions (from 6 to 20 x 10 to the 16th moles) over a period of several hundred thousand years is estimated based on best estimates of the CO2 weight fraction of the original basalts and basaltic melts, the fraction of CO2 degassed, and the volume of the Deccan Traps eruptions. Results of a model designed to estimate the effects of increased CO2 on climate and ocean chemistry suggest that increases in atmospheric pCO2 due to Deccan Traps CO2 emissions would have been less than 75 ppm, leading to a predicted global warming of less than 1 C over several hundred thousand years. It is concluded that the direct climate effects of CO2 emissions from the Deccan eruptions would have been too weak to be an important factor in the end-Cretaceous mass extinctions.

  10. Efficient plasmonic emission by the quantum Čerenkov effect from hot carriers in graphene

    NASA Astrophysics Data System (ADS)

    Kaminer, Ido; Katan, Yaniv Tenenbaum; Buljan, Hrvoje; Shen, Yichen; Ilic, Ognjen; López, Josué J.; Wong, Liang Jie; Joannopoulos, John D.; Soljačić, Marin

    2016-06-01

    Graphene plasmons have been found to be an exciting plasmonic platform, thanks to their high field confinement and low phase velocity, motivating contemporary research to revisit established concepts in light-matter interaction. In a conceptual breakthrough over 80 years old, Čerenkov showed how charged particles emit shockwaves of light when moving faster than the phase velocity of light in a medium. To modern eyes, the Čerenkov effect offers a direct and ultrafast energy conversion scheme from charge particles to photons. The requirement for relativistic particles, however, makes Čerenkov emission inaccessible to most nanoscale electronic and photonic devices. Here we show that graphene plasmons provide the means to overcome this limitation through their low phase velocity and high field confinement. The interaction between the charge carriers flowing inside graphene and the plasmons enables a highly efficient two-dimensional Čerenkov emission, giving a versatile, tunable and ultrafast conversion mechanism from electrical signal to plasmonic excitation.

  11. Effect of an X-Class Solar Flare on the OI 630 nm Dayglow Emissions

    NASA Technical Reports Server (NTRS)

    Das, Uma; Pallamraju, Duggirala; Chakrabarti, Supriya

    2010-01-01

    We present a striking event that shows a prompt effect of an X-class solar flare (X6.2/3B) in the neutral optical dayglow emissions. This flare occurred on 13 December 2001 at 1424 UT and peaked at 1430 UT. The peak-to pre-flare X-ray intensity ratio as observed by GOES-10 was greater than 300 and the EUV flux observed by SEM/SOHO was greater by around 60%. As a response to this flare, the daytime redline (OI 630 nm) column integrated emission intensity measured from Carmen Alto (23.16degS, 70.66degW), in Chile, showed a prompt increase of around 50%. Our results show that this prompt enhancement in the thermospheric dayglow seems to be caused mainly due to an increase in photoelectrons due to a sudden increase in the solar EUV flux associated with this flare.

  12. Evaluation of the effects of a new combustion system and catalyst on engine emissions

    SciTech Connect

    Corbo, P.; Corcione, F.E.; Vaglieco, B.M.

    1990-01-01

    The paper reports the results of an experimental investigation carried out on a four-stroke single-cylinder D.I. diesel engine (100 {times} 95mm bore {times} stroke) with the aim to evaluate the effects of a four-lobe square combustion chamber on the gaseous and particulate emissions. Fluid-dynamic behaviour of the axisymmetric toroidal and four-lobe square chambers was investigated by Laser Doppler Anemometry. Engine tests at 2000 and 3000 rpm for different state of combustion (SOC) and A/F ratio are reported. Particulate, HC and NO{sub x} emission index measured under different operating conditions are given. In addition, the volatile content of the particulates produced from the two chambers at various engine operative conditions was measured by thermogravimetric analysis (TGA). Finally, the catalytic activity of a metal-oxide-based catalyst in the combustion of particulate was also evaluated by TGA.

  13. Assessing the relative effects of emissions, climate means, and variability on large water supply systems

    NASA Astrophysics Data System (ADS)

    Whateley, Sarah; Brown, Casey

    2016-11-01

    Some of the greatest societal risks of climate change rise from the potential impacts to water supply. Yet prescribing adaptation policies in the near term is made difficult by the uncertainty in climate projections at relevant spatial scales and the conflating effects of uncertainties in emissions, model error, and internal variability. In this work, a new framework is implemented to explore the vulnerability of reservoir systems in the northeastern U.S. to climate change and attribute vulnerabilities to changes in mean climate, natural variability, or emission scenarios. Analysis of variance is used to explore the contributions of uncertainties to system performance. Diagnosing the relative risks to water supply will help water resource engineers better adapt to uncertain future conditions. The results indicate that uncertainty in water supply system performance can be attributed mostly to uncertainty in internal variability over policy-relevant planning horizons, and thus, adaptation efforts should focus on managing variability.

  14. Effect of discharge duct geometry on centrifugal fan performance and noise emission

    NASA Astrophysics Data System (ADS)

    Nelson, David A.; Butrymowicz, William; Thomas, Christopher

    2005-09-01

    Non-ideal inlet and discharge duct geometries can cause significant changes to both the aerodynamic performance (``fan curve'') and specific sound power emission of a fan. A proper understanding of actual installed performance, as well as a good estimate of the system backpressure curve, is critical to achieving flow and acoustic goals as well as other criteria such as power consumption, mass and volume. To this end a battery of ISO 10302 tests was performed on a blower assembly which supports the Advanced Animal Habitat, being developed by ORBITEC for deployment on the International Space Station. The blower assembly consists of (4) identical centrifugal fans that, amongst themselves and across two prototypes, incorporated several discharge geometries. The inlet geometries were identical in all cases. Thus by comparing the dimensionless pressure-flow and noise emission characteristics across the cases, significant insight into the nature and potential magnitude of these effects is gained.

  15. Paradoxical solvent effects on the absorption and emission spectra of amino-substituted perylene monoimides.

    PubMed

    Zoon, Peter D; Brouwer, Albert M

    2005-08-12

    In N-(2,5-di-tert-butylphenyl)-9-pyrrolidinoperylene-3,4-dicarboximide (5PI) the absorption and emission spectra display large solvatochromic shifts, but, remarkably, the Stokes shift is practically independent of solvent polarity. This unique behavior is caused by the extraordinarily large ground-state dipole moment of 5PI, which further increases upon increasing the solvent polarity, whereas the excited-state dipole moment is less solvent dependent. In the corresponding piperidine compound, 6PI, this effect is much less important owing to the weaker coupling between the amino group and the aromatic imide moiety, and in the corresponding naphthalimide, 5NI, it is absent. The latter shows the conventional solvatochromic behavior of a push-pull substituted conjugated system, that is, minor shifts in absorption and a larger change in the emission energy with solvent polarity.

  16. [Effects of typical herbicides on soil respiration and N2O emissions from soil added with different nitrogen fertilizers].

    PubMed

    Sun, Qing; Shi, Chun-Xing; Shi, Kun; Yan, Ru-Bin; Jiang, Jing-Yan; Wu, Yi-Zhong

    2012-06-01

    To investigate the effects of typical herbicides on soil respiration and N2O emissions from soil added with different nitrogen fertilizers, a laboratory incubation experiment was carried out using a modified gas chromatograph (Agilent 4890D) method. The results showed that with (NH4)2SO4 amendment, soil respiration and N2O emissions from the Atrazine and Paraquat treatments had no significant difference in comparison to the control (P > 0.05). Glyphosate significantly inhibited soil respiration by 21.5% (P < 0.05) and had no obvious influence on N2O emissions (P > 0.05). Tribenuron-methyl significantly promoted soil respiration with the increase of 14.3% (P < 0.05) and also had no obvious influence on N2O emissions (P > 0.05). Acetochlor significantly increased soil respiration and N2O emissions (P < 0.05) with the increase of 6.1% and 45.1%, respectively. With urea application, Atrazine and Acetochlor had no significant influence on soil respiration and N2O emissions (P > 0.05). Paraquat increased N2O emissions significantly (P < 0.05)with the increase of 43.5% and had no significant influence on soil respiration ( P > 0.05). Glyphosate significantly inhibited soil respiration by 17.5% (P < 0.05), and had no significant influence on N2O emissions (P > 0.05). Tribenuron-methyl enhanced soil respiration and N2O emissions significantly (P < 0.05), and its soil respiration and N2O emissions were 1.3 and 1.6 times higher than those from the control. Due to the complexity of effects of different herbicides on microbial physiological metabolism, long-term in-situ studies need to be carried out to better understand the effect of various herbicides on greenhouse gas emissions.

  17. Burstein-Moss Effect Behind Au Surface Plasmon Enhanced Intrinsic Emission of ZnO Microdisks

    NASA Astrophysics Data System (ADS)

    Zhu, Qiuxiang; Lu, Junfeng; Wang, Yueyue; Qin, Feifei; Shi, Zengliang; Xu, Chunxiang

    2016-11-01

    In this paper, ZnO microdisks with sputtering of Au nanoparticles were prepared to explore their plasmon/exciton coupling effect. An obvious blue shift and enhanced excitonic emission intensity were observed in the PL spectra of as-grown and Au-sputtered ZnO samples at room temperature. The investigation on the absorption spectra and temperature-dependent PL spectra has been demonstrated the Burstein-Moss effect behind the optical phenomena. These results revealed the coupling dynamics between the metal localized surface plasmon and semiconductor exciton.

  18. Burstein-Moss Effect Behind Au Surface Plasmon Enhanced Intrinsic Emission of ZnO Microdisks

    PubMed Central

    Zhu, Qiuxiang; Lu, Junfeng; Wang, Yueyue; Qin, Feifei; Shi, Zengliang; Xu, Chunxiang

    2016-01-01

    In this paper, ZnO microdisks with sputtering of Au nanoparticles were prepared to explore their plasmon/exciton coupling effect. An obvious blue shift and enhanced excitonic emission intensity were observed in the PL spectra of as-grown and Au-sputtered ZnO samples at room temperature. The investigation on the absorption spectra and temperature-dependent PL spectra has been demonstrated the Burstein-Moss effect behind the optical phenomena. These results revealed the coupling dynamics between the metal localized surface plasmon and semiconductor exciton. PMID:27805012

  19. Trophic-level dependent effects on CO2 emissions from experimental stream ecosystems.

    PubMed

    Atwood, Trisha B; Hammill, Edd; Richardson, John S

    2014-11-01

    Concern over accelerating rates of species invasions and losses have initiated investigations into how local and global changes to predator abundance mediate trophic cascades that influence CO2 fluxes of aquatic ecosystems. However, to date, no studies have investigated how species additions or losses at other consumer trophic levels influence the CO2 flux of aquatic ecosystems. In this study, we added a large predatory stonefly, detritivorous stonefly, or grazer tadpole to experimental stream food webs and over a 70-day period quantified their effects on community composition, leaf litter decomposition, chlorophyll-a concentrations, and stream CO2 emissions. In general, streams where the large grazer or large detritivore were added showed no change in total invertebrate biomass, leaf litter loss, chlorophyll-a concentrations, or stream CO2 emissions compared with controls; although we did observe a spike in CO2 emissions in the large grazer treatment following a substantial reduction in chlorophyll-a concentrations on day 28. However, the large grazer and large detritivore altered the community composition of streams by reducing the densities of other grazer and detritivore taxa, respectively, compared with controls. Conversely, the addition of the large predator created trophic cascades that reduced total invertebrate biomass and increased primary producer biomass. The cascading effects of the predator additions on the food web ultimately led to decreased CO2 emissions from stream channels by up to 95%. Our results suggest that stream ecosystem processes were more influenced by changes in large predator abundance than large grazer or detritivore abundance, because of a lack of functionally similar large predators. Our study demonstrates that the presence/absence of species with unique functional roles may have consequences for the exchange of CO2 between the ecosystem and the atmosphere.

  20. Potential sensitivity of photosynthesis and isoprene emission to direct radiative effects of atmospheric aerosol pollution

    NASA Astrophysics Data System (ADS)

    Strada, Susanna; Unger, Nadine

    2016-04-01

    A global Earth system model is applied to quantify the impacts of direct anthropogenic aerosol effective radiative forcing on gross primary productivity (GPP) and isoprene emission. The impacts of different pollution aerosol sources (anthropogenic, biomass burning, and non-biomass burning) are investigated by performing sensitivity experiments. The model framework includes all known light and meteorological responses of photosynthesis, but uses fixed canopy structures and phenology. On a global scale, our results show that global land carbon fluxes (GPP and isoprene emission) are not sensitive to pollution aerosols, even under a global decline in surface solar radiation (direct + diffuse) by ˜ 9 %. At a regional scale, GPP and isoprene emission show a robust but opposite sensitivity to pollution aerosols in regions where forested canopies dominate. In eastern North America and Eurasia, anthropogenic pollution aerosols (mainly from non-biomass burning sources) enhance GPP by +5-8 % on an annual average. In the northwestern Amazon Basin and central Africa, biomass burning aerosols increase GPP by +2-5 % on an annual average, with a peak in the northwestern Amazon Basin during the dry-fire season (+5-8 %). The prevailing mechanism varies across regions: light scattering dominates in eastern North America, while a reduction in direct radiation dominates in Europe and China. Aerosol-induced GPP productivity increases in the Amazon and central Africa include an additional positive feedback from reduced canopy temperatures in response to increases in canopy conductance. In Eurasia and northeastern China, anthropogenic pollution aerosols drive a decrease in isoprene emission of -2 to -12 % on an annual average. Future research needs to incorporate the indirect effects of aerosols and possible feedbacks from dynamic carbon allocation and phenology.

  1. The effects of carbon tax on the Oregon economy and state greenhouse gas emissions

    NASA Astrophysics Data System (ADS)

    Rice, A. L.; Butenhoff, C. L.; Renfro, J.; Liu, J.

    2014-12-01

    Of the numerous mechanisms to mitigate greenhouse gas emissions on statewide, regional or national scales in the United States, a tax on carbon is perhaps one of the simplest. By taxing emissions directly, the costs of carbon emissions are incorporated into decision-making processes of market actors including consumers, energy suppliers and policy makers. A carbon tax also internalizes the social costs of climate impacts. In structuring carbon tax revenues to reduce corporate and personal income taxes, the negative incentives created by distortionary income taxes can be reduced or offset entirely. In 2008, the first carbon tax in North America across economic sectors was implemented in British Columbia through such a revenue-neutral program. In this work, we investigate the economic and environmental effects of a carbon tax in the state of Oregon with the goal of informing the state legislature, stakeholders and the public. The study investigates 70 different economic sectors in the Oregon economy and six geographical regions of the state. The economic model is built upon the Carbon Tax Analysis Model (C-TAM) to provide price changes in fuel with data from: the Energy Information Agency National Energy Modeling System (EIA-NEMS) Pacific Region Module which provides Oregon-specific energy forecasts; and fuel price increases imposed at different carbon fees based on fuel-specific carbon content and current and projected regional-specific electricity fuel mixes. CTAM output is incorporated into the Regional Economic Model (REMI) which is used to dynamically forecast economic impacts by region and industry sector including: economic output, employment, wages, fiscal effects and equity. Based on changes in economic output and fuel demand, we further project changes in greenhouse gas emissions resulting from economic activity and calculate revenue generated through a carbon fee. Here, we present results of this modeling effort under different scenarios of carbon fee and

  2. Effect of the Temperature-Emissivity Contrast on the Chemical Signal for Gas Plume Detection Using Thermal Image Data.

    PubMed

    Walsh, Stephen; Chilton, Larry; Tardiff, Mark; Metoyer, Candace

    2008-10-21

    Detecting and identifying weak gaseous plumes using thermal imaging data is complicated by many factors. These include variability due to atmosphere, ground and plume temperature, and background clutter. This paper presents an analysis of one formulation of the physics-based radiance model, which describes at-sensor observed radiance. The background emissivity and plume/ground temperatures are isolated, and their effects on chemical signal are described. This analysis shows that the plume's physical state, emission or absorption, is directly dependent on the background emissivity and plume/ground temperatures. It then describes what conditions on the background emissivity and plume/ground temperatures have inhibiting or amplifying effects on the chemical signal. These claims are illustrated by analyzing synthetic hyperspectral imaging data with the adaptive matched filter using two chemicals and three distinct background emissivities.

  3. Photon emission by nanocavity-enhanced quantum anti-Zeno effect in solid-state cavity quantum-electrodynamics.

    PubMed

    Yamaguchi, Makoto; Asano, Takashi; Noda, Susumu

    2008-10-27

    Solid-state cavity quantum-electrodynamics (QED) has great potential owing to advances such as coupled systems combining a nanocavity and a quantum dot (QD). These systems involve two photon-emission mechanisms: the Purcell effect in the weak coupling regime and vacuum Rabi-splitting in the strong coupling regime. In this paper, we describe a third emission mechanism based on the quantum anti-Zeno effect (AZE) induced by the pure-dephasing in a QD. This is significantly enhanced by the inherent characteristics of the nanocavity. This mechanism explains the origin of strong photon emission at a cavity mode largely detuned from a QD, previously considered a counterintuitive, prima facie non-energy-conserving, light-emission phenomenon. These findings could help in controlling the decay and emission characteristics of solid-state cavity QED, and developing solid-state quantum devices.

  4. Effects of organic matter amendments on net primary productivity and greenhouse gas emissions in annual grasslands.

    PubMed

    Ryals, Rebecca; Silver, Whendee L

    2013-01-01

    Most of the world's grasslands are managed for livestock production. A critical component of the long-term sustainability and profitability of rangelands (e.g., grazed grassland ecosystems) is the maintenance of plant production. Amending grassland soils with organic waste has been proposed as a means to increase net primary productivity (NPP) and ecosystem carbon (C) storage, while mitigating greenhouse gas emissions from waste management. Few studies have evaluated the effects of amendments on the C balance and greenhouse gas dynamics of grasslands. We used field manipulations replicated within and across two rangelands (a valley grassland and a coastal grassland) to determine the effects of a single application of composted green waste amendments on NPP and greenhouse gas emissions over three years. Amendments elevated total soil respiration by 18% +/- 4% at both sites but had no effect on nitrous oxide or methane emissions. Carbon losses were significantly offset by greater and sustained plant production. Amendments stimulated both above- and belowground NPP by 2.1 +/- 0.8 Mg C/ha to 4.7 +/- 0.7 Mg C/ha (mean +/- SE) over the three-year study period. Net ecosystem C storage increased by 25-70% without including the direct addition of compost C. The estimated magnitude of net ecosystem C storage was sensitive to estimates of heterotrophic soil respiration but was greater than controls in five out of six fields that received amendments. The sixth plot was the only one that exhibited lower soil moisture than the control, suggesting an important role of water limitation in these seasonally dry ecosystems. Treatment effects persisted over the course of the study, which were likely derived from increased water-holding capacity in most plots, and slow-release fertilization from compost decomposition. We conclude that a single application of composted organic matter can significantly increase grassland C storage, and that effects of a single application are likely to

  5. Spontaneous ultraweak photon emission imaging of oxidative metabolic processes in human skin: effect of molecular oxygen and antioxidant defense system

    NASA Astrophysics Data System (ADS)

    Rastogi, Anshu; Pospíšil, Pavel

    2011-09-01

    All living organisms emit spontaneous ultraweak photon emission as a result of cellular metabolic processes. In this study, the involvement of reactive oxygen species (ROS) formed as the byproduct of oxidative metabolic processes in spontaneous ultraweak photon emission was studied in human hand skin. The effect of molecular oxygen and ROS scavengers on spontaneous ultraweak photon emission from human skin was monitored using a highly sensitive photomultiplier tube and charged coupled device camera. When spontaneous ultraweak photon emission was measured under anaerobic conditions, the photon emission was decreased, whereas under hyperaerobic condition the enhancement in photon emission was observed. Spontaneous ultraweak photon emission measured after topical application of glutathione, α-tocopherol, ascorbate, and coenzyme Q10 was observed to be decreased. These results reveal that ROS formed during the cellular metabolic processes in the epidermal cells play a significant role in the spontaneous ultraweak photon emission. It is proposed that spontaneous ultraweak photon emission can be used as a noninvasive tool for the temporal and spatial monitoring of the oxidative metabolic processes and intrinsic antioxidant system in human skin.

  6. Effects of Retrofitting Emission Control Systems on all In-Use Heavy Diesel Trucks

    NASA Astrophysics Data System (ADS)

    Millstein, D.; Harley, R. A.

    2009-12-01

    Diesel exhaust is now the largest source of nitrogen oxide (NOx) emissions nationally in the US, and contributes significantly to emissions of fine particulate black carbon (soot) as well. New national standards call for dramatically lower emissions of exhaust particulate matter (PM) and NOx from new diesel engines starting in 2007 and 2010, respectively. Unfortunately it will take decades for the cleaner new engines to replace those currently in service on existing heavy-duty trucks. The state of California recently adopted a rule to accelerate fleet turnover in the heavy-duty truck sector, requiring that all in-use trucks meet the new exhaust PM standards by 2014. This will entail retrofit of diesel particle filters or replacement for over a million existing diesel engines. Diesel particle filters can replace the muffler on existing trucks, and there is extensive experience with retrofit of this control equipment on public sector fleets such as diesel-powered transit buses. Nitrogen dioxide (NO2) is used as an oxidizing agent to remove carbon particles from the particle filter, to prevent it from becoming plugged. To create the needed NO2, NOx already present in engine exhaust as nitric oxide (NO) is deliberately oxidized to NO2 upstream of the particle filter using a platinum catalyst. The NO2/NOx ratio in exhaust emissions therefore increases to ~35% in comparison to much lower values (~5%) typical of older engines without particle filters. We evaluate the effects on air quality of increased use of diesel particle traps and NOx controls in southern California using the Community Multiscale Air Quality (CMAQ) model. Compared to a reference scenario without the retrofit program, we found black carbon concentrations decreased by ~20%, with small increases (4%) in ambient ozone concentrations. During summer, average NO2 concentrations decrease despite the increase in primary NO2 emissions - because total NOx emissions are reduced as part of a parallel but more

  7. Effect of inter-row cultivation on soil CO2 emission in a peach plantation

    NASA Astrophysics Data System (ADS)

    Tóth, E.; Farkas, Cs.; Gelybó, Gy.; Lagzi, I.

    2012-04-01

    We examined the effect of inter-row cultivation on soil CO2 emission in a peach plantation planted in 1991. The soil is Ramann type brown forest soil /Mollic Cambisol/ developed on sandy loam. Every second row in the orchard is covered with undisturbed grass, and every other row is disked (depth: 12-15cm) with a two-three-week frequency. The humus content varies from 1,69% to 2,28% in the upper 20 cm layer, where the sand, loam and clay contents are 58%, 21% and 19 %, respectively. The average annual precipitation total is 570 mm (330 mm for the growing season) at the site. During the vegetation period of 2009 soil CO2 emission measurements were carried out with static chamber method in the differently managed rows. Parallel with CO2 measurements soil volumetric water content and soil temperature were also determined. Soil microbiological properties water-extractable organic carbon (WEOC) and water-extractable nitrogen (WEN) as well as substrate-induced respiration (SIR) were determined from disturbed soil samples collected on the first measurement day. The measured soil physical properties showed that different soil management practices influence soil water content, bulk density and soil temperature as well. Soil water content was higher in the grass covered row on 10 of the 13 measurement days, the difference - which reached 10 v% - was the highest on the warmest days. Soil temperature is also different in case of disked and grass covered rows, found to be lower in the grass covered rows on every measurement days. SIR, WEOC and WEN were all higher in the grass covered row (19.45 μg CO2-C g-1 soil 36.91 μg g-1 soil, 139.36 μg g-1 soil, respectively) than in the disked row (4.88 μg CO2-C g-1 soil 25.43 μg C g-1 soil, 61.25 μg N g-1 soil, respectively) in 2009. Soil CO2 emission also differed between the two rows, grass covered rows produced higher emission in all measurements days without exemption. The difference between CO2 fluxes from the two cultivation

  8. Water stress, temperature, and light effects on the capacity for isoprene emission and photosynthesis of kudzu leaves.

    PubMed

    Sharkey, Thomas D; Loreto, Francesco

    1993-09-01

    Kudzu (Pueraria lobata (Willd) Ohwi.) is a vine which forms large, monospecific stands in disturbed areas of the southeastern United States. Kudzu also emits isoprene, a hydrocarbon which can significantly affect atmospheric chemistry including reactions leading to tropospheric ozone. We have studied physiological aspects of isoprene emission from kudzu so the ecological consequences of isoprene emission can be better understood. We examined: (a) the development of isoprene emission as leaves developed, (b) the interaction between photon flux density and temperature effects on isoprene emission, (c) isoprene emission during and after water stress, and (d) the induction of isoprene emission from leaves grown at low temperature by water stress or elevated temperature. Isoprene emission under standard conditions of 1000 μmol photons·m(-2)·s(-1) and 30°C developed only after the leaf had reached full expansion, and was not complete until up to two weeks past the point of full expansion of the leaf. The effect of temperature on isoprene emission was much greater than found for other species, with a 10°C increase in temperature causing a eight-fold increase in the rate of isoprene emission. Isoprene emission from kudzu was stimulated by increases in photon flux density up to 3000 μmol photons·m(-2)·s(-1). In contrast, photosynthesis of kudzu was saturated at less than 1000 μmol·m(-2)·s(-1) photon flux density and was reduced at high temperature, so that up to 20% of the carbon fixed in photosynthesis was reemitted as isoprene gas at 1000 μmol photons·m(-2)·s(-1) and 35°C. Withholding water caused photosynthesis to decline nearly to zero after several days but had a much smaller effect on isoprene emission. Following the relief of water stress, photosynthesis recovered to the prestress level but isoprene emission increased to about five times the prestress rate. At 1000 μmol photons·m(-2)·s(-1) and 35°C as much as 67% of the carbon fixed in

  9. Toxicological effects of particulate emissions - A comparison of oil and wood fuels in small- and medium-scale heating systems

    NASA Astrophysics Data System (ADS)

    Kasurinen, Stefanie; Jalava, Pasi I.; Tapanainen, Maija; Uski, Oskari; Happo, Mikko S.; Mäki-Paakkanen, Jorma; Lamberg, Heikki; Koponen, Hanna; Nuutinen, Ilpo; Kortelainen, Miika; Jokiniemi, Jorma; Hirvonen, Maija-Riitta

    2015-02-01

    The use of wood instead of oil fuels in heating systems is strongly encouraged in many countries. Yet it is unknown to what extent such a large-scale change from oil to wood fuels in heating systems would contribute to any negative health effects from their emissions. We compared the toxicological properties of particulate matter (PM) emissions from wood and oil fuels from two small-scale and two medium-scale heating systems. To assess whether oil or wood combustion emissions cause adverse effects and which PM emissions' effects are more profound, we measured cell viability and proliferation, inflammatory markers, as well as DNA damage in RAW264.7 mouse macrophages. We found that the medium-scale oil-fueled heating system induced a dose-dependent increase of DNA damage, short-term cytotoxic effects, and a cell cycle arrest in the G2/M-phase. We did not detect an induction of DNA damage by the medium-scale wood-fired system. However, we detected significant short-term cytotoxicity. We found that both oil and wood combustion emission samples from the small-scale heating systems induced DNA damage. However, the short-term cytotoxic effects were greater for the PM emissions from the oil-fired heating system. PM mass emissions differed significantly between the tested heating systems. The lowest emissions, 0.1 mg/MJ, were produced by the small-scale oil-fired heating system; the highest emissions, 20.3 mg/MJ, by the medium-scale oil-fired heating system. The wood-fired heating systems' PM mass emissions were in between these concentrations, complicating the direct comparison of the emissions' health related toxic effects. Conclusively, our results indicate that the emissions from both the small- and the medium-scale wood-fueled heating systems cause overall less cytotoxicity and DNA damage in a cell model than the emissions from the corresponding oil-fueled heating systems. Hence, controlled wood-fueled heating systems may be good alternatives to heating systems fired

  10. Effectiveness of Mitigation Measures in Reducing Future Primary Particulate Matter Emissions from On-Road Vehicle Exhaust

    SciTech Connect

    Yan, Fang; Bond, Tami C.; Streets, David G.

    2014-12-16

    This work evaluates the effectiveness of on-road primary particulate matter emission reductions that can be achieved by long-term vehicle scrappage and retrofit measures on regional and global levels. Scenario analysis shows that scrappage can provide significant emission reductions as soon as the measures begin, whereas retrofit provides greater emission reductions in later years, when more advanced technologies become available in most regions. Reductions are compared with a baseline that already accounts for implementation of clean vehicle standards. The greatest global emission reductions from a scrappage program occur 5 to 10 years after its introduction and can reach as much as 70%. The greatest reductions with retrofit occur around 2030 and range from 16-31%. Monte Carlo simulations are used to evaluate how uncertainties in the composition of the vehicle fleet affect predicted reductions. Scrappage and retrofit reduce global emissions by 22-60% and 15-31%, respectively, within 95% confidence intervals, under a midrange scenario in the year 2030. The simulations provide guidance about which strategies are most effective for specific regions. Retrofit is preferable for high-income regions. For regions where early emission standards are in place, scrappage is suggested, followed by retrofit after more advanced emission standards are introduced. The early implementation of advanced emission standards is recommended for Western and Eastern Africa

  11. The effect on highway NO{sub x} emissions of abolishing national speed limits

    SciTech Connect

    Mullen, M.A.; Wilson, J.H. Jr.; Gottsman, L.

    1996-12-31

    The National Highway System bill passed by Congress in 1995 abolished the national maximum speed limit. An analysis performed for EPA during the bill debate provides a comprehensive look at the implications of raising speed limits on highway vehicle NO{sub x} emissions. With the passage of the National Highway System Bill, states have the authority to determine the maximum allowable speed limits for all vehicles within their boundaries. The likely effect of the change in the law was-and has turned out to be-raised speed limits on rural freeways. This analysis projects NO{sub x} emissions rising by 5 percent nationally with expected higher speed limits. States such as Montana, North Dakota, and South Dakota that have high rural Interstate VMT relative to urban VMT show the highest NO{sub x} increases. By contrast, states like New Jersey, California, and Illinois with a preponderance of urban travel show relatively small projected emission increases from the speed change. This paper also reviews current speed limit status in the fifty states. However, because states may change their limits at any time, it does not analyze an end result of the change in the law.

  12. The Effect of Molecular Contamination on the Emissivity Spectral Index in Orion A

    NASA Astrophysics Data System (ADS)

    Coudé, Simon; Bastien, Pierre; Drabek, Emily; Johnstone, Doug; Hatchell, Jennifer

    2013-07-01

    The emissivity spectral index is a critical component in the study of the physical properties of dust grains in cold and optically thin interstellar star forming regions. Since submillimeter astronomy is an ideal tool to measure the thermal emission of those dust grains, it can be used to characterize this important parameter. We present the SCUBA-2 shared risks observations at 450 μm and 850 μm of the Orion A molecular cloud obtained at the James-Clerk-Maxwell telescope. Previous studies showed that molecular emission lines can also contribute significantly to the measured fluxes in those continuum bands. We use HARP 12CO 3-2 maps to evaluate the total molecular line contamination in the SCUBA-2 maps and its effect on the determination of the spectral index in highly contaminated areas. With the corrected fluxes, we have obtained new spectral index maps for different regions of the well-known integral-shaped filament. This work is part of an ongoing effort to characterize the properties of star forming regions in the Gould belt with the new instruments available at the JCMT.

  13. Effect of localized surface-plasmon mode on exciton transport and radiation emission in carbon nanotubes.

    PubMed

    Roslyak, Oleksiy; Cherqui, Charles; Dunlap, David H; Piryatinski, Andrei

    2014-07-17

    We report on a general theoretical approach to study exciton transport and emission in a single-walled carbon nanotube (SWNT) in the presence of a localized surface-plasmon (SP) mode within a metal nanoparticle interacting via near-field coupling. We derive a set of quantum mechanical equations of motion and approximate rate equations that account for the exciton, SP, and the environmental degrees of freedom. The material equations are complemented by an expression for the radiated power that depends on the exciton and SP populations and coherences, allowing for an examination of the angular distribution of the emitted radiation that would be measured in experiment. Numerical simulations for a (6,5) SWNT and cone-shaped Ag metal tip (MT) have been performed using this methodology. Comparison with physical parameters shows that the near-field interaction between the exciton-SP occurs in a weak coupling regime, with the diffusion processes being much faster than the exciton-SP population exchange. In such a case, the effect of the exciton population transfer to the MT with its subsequent dissipation (i.e., the Förster energy transfer) is to modify the exciton steady state distribution while reducing the equilibration time for excitons to reach a steady sate distribution. We find that the radiation distribution is dominated by SP emission for a SWNT-MT separation of a few tens of nanometers due to the fast SP emission rate, whereas the exciton-SP coherences can cause its rotation.

  14. Emission angle dependence of fission fragment spin: Effects of single particle spin and tilting mode

    NASA Astrophysics Data System (ADS)

    Datta, T.; Naik, H.; Dange, S. P.

    1995-06-01

    The high-spin yield fraction (HSF) for the fission product 132Im,g has been measured as a function of fragment emission angle (90° >=Θ>=10°) in the 237Np(α29 MeV,f) system. It was seen that the HSF for 132I or corresponding fragment (~=134I) spin initially decreases as emission angle decreases from 90° to ~=45° and then steadily increases at lower angles (Θ<45°). Contrary to the present observation in odd-Z 241Am fission, earlier we had observed that fragment spin continuously decreases to a limit with decrease in emission angle from 90° to 20° in even-even 242Pu fission. These data have been analyzed in the framework of the collective mode model invoking the effect of single particle spin. It is seen that for an odd-Z or A fissioning nucleus, angular variation of fragment spin could be accounted for on the basis of coupling between the odd nucleon spin (j>=k~=4ħ) projections and spin due to the collective rotational (tilting) degrees. Collective rotational degrees govern fragment spin for even-even fissioning nucleus.

  15. Effects of regional temperature on electric vehicle efficiency, range, and emissions in the United States.

    PubMed

    Yuksel, Tugce; Michalek, Jeremy J

    2015-03-17

    We characterize the effect of regional temperature differences on battery electric vehicle (BEV) efficiency, range, and use-phase power plant CO2 emissions in the U.S. The efficiency of a BEV varies with ambient temperature due to battery efficiency and cabin climate control. We find that annual energy consumption of BEVs can increase by an average of 15% in the Upper Midwest or in the Southwest compared to the Pacific Coast due to temperature differences. Greenhouse gas (GHG) emissions from BEVs vary primarily with marginal regional grid mix, which has three times the GHG intensity in the Upper Midwest as on the Pacific Coast. However, even within a grid region, BEV emissions vary by up to 22% due to spatial and temporal ambient temperature variation and its implications for vehicle efficiency and charging duration and timing. Cold climate regions also encounter days with substantial reduction in EV range: the average range of a Nissan Leaf on the coldest day of the year drops from 70 miles on the Pacific Coast to less than 45 miles in the Upper Midwest. These regional differences are large enough to affect adoption patterns and energy and environmental implications of BEVs relative to alternatives.

  16. Dynamic Stark effect, light emission, and entanglement generation in a laser-driven quantum optical system

    NASA Astrophysics Data System (ADS)

    Pagel, D.; Alvermann, A.; Fehske, H.

    2017-01-01

    We calculate the emission spectra, the Glauber g(2 ) function, and the entanglement of formation for two-level emitters coupled to a single cavity mode and subject to an external laser excitation. To evaluate these quantities we couple the system to environmental degrees of freedom, which leads to dissipative dynamics. Because of the periodic time dependence of the system Hamiltonian, the coefficients of the Markovian master equation are constant only if Floquet states are used as the computational basis. Studying the emission spectra, we show that the dynamic Stark effect first appears in second order of the laser intensity. For the Glauber function, we find clearly distinguished parameter regimes of super- and sub-Poissonian light emission and explain the additional features appearing for finite laser intensity in terms of the quasienergy spectrum of the driven emitter-cavity system. Finally, we analyze the temperature and emitter-cavity-coupling regimes where entanglement among the emitters is generated and show that the laser excitation leads to a decrease of entanglement.

  17. Chemical effects of CeL(gamma4) emission spectra for Ce compounds.

    PubMed

    Hayashi, Hisashi; Takehara, Yuki; Kawamura, Naomi; Mizumaki, Masaichiro

    2010-01-01

    High-resolution CeL(gamma4) emission spectra of CeF(3), Ce(2)S(3), CeF(4), and CeO(2) have been measured using a multicrystal, multidetector spectrometer. The spectra exhibited substantial differences depending on the chemical environment of the Ce ions. By comparing the observed CeO(2) spectrum with the band calculations, we determined that the observed chemical effects of the main emission line were primarily attributable to the transitions of the Ce5p band; the high-energy tail at around 6.539 keV was assigned to the ligand p-->Ce2s cross transition. Further, a key difference between CeL(gamma4) and EuL(gamma4) is discussed with reference to CeL(1)- and EuL(1)-X-ray absorption fine-structures (XAFS). Possible applications of CeL(gamma4) emissions to material characterization are also suggested.

  18. Effect of sequential surface irrigations on field-scale emissions of 1,3-dichloropropene.

    PubMed

    Yates, S R; Knuteson, J; Ernst, F F; Zheng, W; Wang, Q

    2008-12-01

    A field experiment was conducted to measure subsurface movement and volatilization of 1,3-dichloropropene (1,3-D) after shank injection to an agricultural soil. The goal of this study was to evaluate the effect of sprinkler irrigation on the emissions of 1,3-D to the atmosphere and is based on recent research that has shown that saturating the soil pore space reduces gas-phase diffusion and leads to reduced volatilization rates. Aerodynamic, integrated horizontal flux, and theoretical profile shape methods were used to estimate fumigant volatilization rates and total emission losses. These methods provide estimates of the volatilization rate based on measurements of wind speed, temperature, and 1,3-D concentration in the atmosphere. The volatilization rate was measured continuously for 16 days, and the daily peak volatilization rates for the three methods ranged from 18 to 60 microg m(-2) s(-1). The total 13-D mass entering the atmosphere was approximately 44-68 kg ha(-1), or 10-15% of the applied active ingredient This represents approximately 30-50% reduction in the total emission losses compared to conventional fumigant applications in field and field-plot studies. Significant reduction in volatilization of 1,3-D was observed when five surface irrigations were applied to the field, one immediately after fumigation followed by daily irrigations.

  19. Effect of degree of fuel vaporization on emissions for a premixed-prevaporized combustor system

    NASA Technical Reports Server (NTRS)

    Cooper, L. P.

    1979-01-01

    The impact of the degree of fuel vaporization upon emission from a flametube combustor was studied using an inlet air pressure of 3 x 10 to the 5th power pascals, inlet air temperatures of 600K and 700K, a reference velocity of 35 meters per second and equivalence ratios of .6 and .72 using Jet A fuel. Incoming air was preheated to temperatures from 600K to 700K by a nonvitiating preheater. Jet A fuel was injected into this airstream through two different fuel injectors manifolded together and mounted in series upstream of a watercooled preforated plate flameholder. The fuel-air mixture burned in a watercooled combustor section. Samples of the fuel-air mixture upstream of the flameholder were obtained for analysis to determine the local degree of fuel vaporization and the fuel-air ratio. Samples of the combustion products were analyzed to determine gaseous emissions. The effects of vaporization on carbon monoxide and nitric on carbon monoxide and nitric oxide emissions are presented.

  20. The effect of functional forms of nitrogen on fuel-NOx emissions.

    PubMed

    Zhang, Linghui; Su, Dagen; Zhong, Mingfeng

    2015-01-01

    This work explores the effects of different nitrogen functional forms on fuel-NOx emissions at 900 °C. The majority of tests are performed with an excess air coefficient of 1.4. Fuel-NOx is detected by measuring N-(1-naphthyl) ethylenediamine dihydrochloride (C₁₂H₁₆Cl₂N₂) via spectrophotometry. The different functional forms of nitrogen in the raw materials are identified by using X-ray photoelectron spectroscopy (XPS). A reliable density functional theory (DFT) method at the B3LYP/6-311++G** level is employed to investigate the reaction pathways of all functional forms of nitrogen during combustion. The results indicate that the functional forms of nitrogen influence the formation of nitrogen oxides. While under the same experimental conditions, fuel-NOx emissions increase by using less activation energy and nitrogen-containing groups with poor thermal stability. It is determined that fuel-NOx emissions vary in the following order: glycine > pyrrole > pyridine > methylenedi-p-phenylene diisocyanate (MDI). Glycine is the chain structure of amino acids in waste-leather and has low activation energy and poor thermal stability. With these properties, it is noted that glycine produces the most fuel-NOx in all of the raw materials studied. More pyrrole than pyridine in coal lead to high yields of fuel-NOx. The lowest yields of fuel-NO x are obtained using polyurethanes in waste-PU.

  1. The Effects of Thermal Barrier Coatings on Diesel Engine Performance and Emission

    NASA Astrophysics Data System (ADS)

    Das, D.; Majumdar, G.; Sen, R. S.; Ghosh, B. B.

    2014-01-01

    The purpose of this paper is to determine the effect of coating thickness on performance and emission of a diesel engine including comparisons with results from an uncoated piston diesel engine. Primarily three piston crowns were coated with Al2O3 (bond coat) of 100 μm thickness each by using Plasma spray coating technique. Then these piston crowns were coated with partially stabilized zirconia with a thickness of 250, 350, 450 μm respectively by using the same technique over the bond coat. These pistons inserted into the cylinder of a diesel engine one by one to collect the combustion and emission data. Then these data were compared with standard diesel engine. It was observed that the thermal efficiency increased with increasing load levels, whereas specific fuel consumption reduced with increasing load. However, it was observed that harmful gases and particulates like CO, smoke and HC were reduced in case of all types of coated piston engine with the increase of load. Increased amount of NOX emission was reported during the experimentation.

  2. Effect of oxygenated fuels on physicochemical and toxicological characteristics of diesel particulate emissions.

    PubMed

    Zhang, Zhi-Hui; Balasubramanian, Rajasekhar

    2014-12-16

    A systematic study was conducted to make a comparative evaluation of the effects of blending five different oxygenates (diglyme (DGM), palm oil methyl ester (PME), dimethyl carbonate (DMC), diethyl adipate (DEA), and butanol (Bu)) with ultralow sulfur diesel (ULSD) at 2% and 4% oxygen levels on physicochemical and toxicological characteristics of particulate emissions from a nonroad diesel engine. All blended fuels led to an overall decrease in the particulate mass concentration and elemental carbon (EC) emissions, which was strongly associated with the oxygen content in fuels and the specific type of fuels used. In general, the proportion of particulate-bound organic carbon (OC) and water-soluble organic carbon (WSOC) increased while using oxygenated fuel blends. Compared to ULSD, all fuel blends showed different emission factors of particle-phase PAHs and n-alkanes, slight alterations in soot nanostructure, lower soot ignition temperature, and lower activation energy. The total counts of particles (≤ 560 nm diameter) emitted decreased gradually for ULSD blended with DMC, DEA, and Bu, while they increased significantly for other fuel blends. The in vitro toxicity of particulates significantly increased with ULSD blended with DMC and DEA, while it decreased when ULSD was blended with PME, DGM, and Bu.

  3. Cost Effective Measures to Reduce CO2 Emissions in the Air Freight Sector

    NASA Technical Reports Server (NTRS)

    Blinge, Magnus

    2003-01-01

    This paper presents cost effective measures to reduce CO2 emissions in the air freight sector. One door-to-door transport chain is studied in detail from a Scandinavian city to a city in southern Europe. The transport chain was selected by a group of representatives from the air freight sector in order to encompass general characteristics within the sector. Three different ways of shipping air cargo are studied, i.e., by air freighter, as belly freight (in passenger aircrafts) and trucking. CO2 emissions are calculated for each part of the transport chain and its relative importance towards the total amount CO2 emitted during the whole transport chain is shown. It is confirmed that the most CO2 emitting part of the transport chain is the actual flight and that it is in the take-off and climbing phases that most fuel are burned. It is also known that the technical development of aircraft implies a reduction in fuel consumption for each new generation of aircraft. Thus, the aircraft manufacturers have an important role in this development. Having confirmed these observations, this paper focuses on other factors that significantly affects the fuel consumption. Analyzed factors are, e.g., optimization of speed and altitude, traffic management, congestion on and around the airfields, tankering, "latest acceptance time" for goods and improving the load factor. The different factors relative contribution to the total emission levels for the transport chain has been estimated.

  4. Weak Emission-line Quasars in the Context of a Modified Baldwin Effect

    NASA Astrophysics Data System (ADS)

    Shemmer, Ohad

    2016-01-01

    Based on spectroscopic data for a sample of high-redshift quasars, I will show that the anti-correlation between the rest-frame equivalent width (EW) of the C IV λ1549 broad-emission line and the Hβ-based Eddington ratio extends across the widest possible ranges of redshift (0 < z < 3.5) and bolometric luminosity(~1044 < L < ~1048 erg s-1). Given this anti-correlation, hereby referred to as a modified Baldwin effect (MBE), weak emission line quasars (WLQs), typically showing EW(C IV) < ~10 Å, are expected to have extremely high Eddington ratios (L/LEdd > ~4). I will present new near-infrared spectroscopy of the broad Hβ line, as well as complementary EW(C IV) information, for all WLQs for which such information is currently available, nine sources in total. I will show that while four of these WLQs can be accommodated by the MBE, the otherfive deviate significantly from this relation, at the > ~3σ level, by exhibiting C IV lines much weaker than predicted from their Hβ-based Eddington ratios. Assuming the supermassive black hole masses in all quasars can be determined reliably using the single-epoch Hβ-method, these results indicate that EW(C IV)cannot depend solely on the Eddington ratio. I will briefly discuss a strategy for further investigation into the roles that basic physical properties play in controlling the relative strengths of broad-emission lines in quasars.

  5. High-temperature annealing effects on multiwalled carbon nanotubes: electronic structure, field emission and magnetic behaviors.

    PubMed

    Ray, Sekhar Chandra; Pao, Chih-Wen; Tsai, Huang-Ming; Chen, Huang-Chin; Chen, Yu-Shin; Wu, Shang-Lun; Ling, Dah-Chin; Lin, I-Nan; Pong, Way-Faung; Gupta, Sanju; Giorcelli, Mauro; Bianco, Stefano; Musso, Simone; Tagliaferro, Alberto

    2009-12-01

    This work elucidates the effects of high-temperature annealing on the microscopic and electronic structure of multiwalled carbon nanotubes (MWCNTs) using high-resolution transmission electron microscopy, micro-Raman spectroscopy, X-ray diffraction, X-ray absorption near-edge structure (XANES) and valence-band photoemission spectroscopy (VBPES), respectively. The field emission and magnetization behaviors are also presented. The results of annealing are as follows: (1) MWCNTs tend to align in the form of small fringes along their length, promote graphitization and be stable in air, (2) XANES indicates an enhancement in oxygen content on the sample, implying that it can be adopted for sensing and storing oxygen gas, (3) the electron field emission current density (J) is enhanced and the turn-on electric field (E(TOE)) reduced, suggesting potential use in field emission displays and as electron sources in microwave tube amplifiers and (4) as-grown MWCNTs with embedded iron nanoparticles exhibits significantly higher coercivity approximately 750 Oe than its bulk counterpart (Fe(bulk) approximately 0.9 Oe), suggesting its potential use as low-dimensional high-density magnetic recording media.

  6. Effect of Scattering on the Combined Reflection and Thermal Radiation Emission of a Typical Semitransparent TBC Material

    NASA Technical Reports Server (NTRS)

    Spuckler, Charles M.

    2004-01-01

    A parametric study was undertaken to examine the effects of scattering on the combined reflection and thermal radiation emission of a typical semi-transparent thermal barrier coating material. A one dimensional model was used.

  7. Effect of solvents on the photoluminescence emission of a few novel, light emitting, segmented block copolymers and hybrid polymers

    NASA Astrophysics Data System (ADS)

    Varma, Sreekanth J.; Mohan, Ranjini R.; Vidya, G.; Jayalekshmi, S.; Prathapan, S.

    2014-01-01

    Numerous light emitting polymers and copolymers with excellent luminescence characteristics and thermal stability are being synthesized and extensively investigated for applications as emissive layers in polymer light emitting diodes. In the present study, three novel, thermally stable, segmented block copolymers (SBC) and two hybrid polymers with excellent photoluminescence (PL) and electroluminescence emission (EL) characteristics were subjected to spectroscopic investigations to explore the effect of various aromatic and non-aromatic solvents on the photoluminescence emission characteristics. Dilute solutions of the SBCs and the hybrid polymers were made from various solvents like dichloromethane, chlorobenzene, tetrahydrofuran, xylene, chloroform, etc. UV-Vis absorption and PL emission spectra of these polymer solutions were recorded simultaneously. No significant changes in the PL emission peaks were observed, depending on the nature of solvents. The effect of solvents in terms of aggregation effects in these polymers was studied. The low aggregation effects and solvent independent nature of the polymers offer very high prospects in various optoelectronic device applications. The present study can be of great use in designing efficient polymer LEDs based on these SBCs and hybrid polymers as emissive layers. The efficiency and stability of the polymer LEDs can be considerably improved by suitably choosing the solvent for the emissive polymers.

  8. Isotope and temperature effects in liquid water probed by x-ray absorption and resonant x-ray emission spectroscopy.

    PubMed

    Fuchs, O; Zharnikov, M; Weinhardt, L; Blum, M; Weigand, M; Zubavichus, Y; Bär, M; Maier, F; Denlinger, J D; Heske, C; Grunze, M; Umbach, E

    2008-01-18

    High-resolution x-ray absorption and emission spectra of liquid water exhibit a strong isotope effect. Further, the emission spectra show a splitting of the 1b1 emission line, a weak temperature effect, and a pronounced excitation-energy dependence. They can be described as a superposition of two independent contributions. By comparing with gas phase, ice, and NaOH/NaOD, we propose that the two components are governed by the initial state hydrogen bonding configuration and ultrafast dissociation on the time scale of the O 1s core hole decay.

  9. An Intrinsic Baldwin Effect in the H Beta Broad Emission Line in the Spectrum of NGC 5548

    NASA Technical Reports Server (NTRS)

    Gilbert, Karoline M.; Peterson, Bradley M.

    2003-01-01

    We investigate the possibility of an intrinsic Baldwin effect (i.e., nonlinear emission-line response to continuum variations) in the broad HP emission line of the active galaxy NGC 5548 using crosscorrelation techniques to remove light-travel time effects from the data. We find a nonlinear relationship between the HP emission line and continuum fluxes that is in good agreement with theoretical predictions. We suggest that similar analysis of multiple lines might provide a useful diagnostic of physical conditions in the broad-line region.

  10. Spin-orbit effects in two-electron emission from ferromagnetic surfaces

    NASA Astrophysics Data System (ADS)

    Giebels, F.; Gollisch, H.; Feder, R.

    2013-10-01

    In previous experiments on electron-induced two-electron emission from the ferromagnetic surface system Co/W(110), spin-orbit coupling effects have been observed, which are comparable in size to the magnetic exchange effects. The present theoretical work aims at a detailed understanding of such effects, in particular their relation to the spin-dependent electronic structure and to collision dynamics. To this end, we have developed a formalism, which is based on a Dirac equation with an effective magnetic field. Magnetic exchange and spin-orbit coupling are thus incorporated simultaneously. Typical numerical two-electron emission results are presented for W(110) and for ultrathin Co films on W(110) together with the underlying spin- and layer-resolved valence electron spectral density. More detailed insight is provided by calculations, in which SOC was selectively switched off for the valence electron and for the primary and emitted electrons. Our theoretical results are in overall agreement with the experimental data. Furthermore, we predict sizable magnetic dichroism.

  11. 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.

  12. NASA Alternative-Fuel Effects on Contrails and Cruise Emissions (ACCESS) Flight Experiments

    NASA Astrophysics Data System (ADS)

    Anderson, B. E.; Moore, R.; Beyersdorf, A. J.; Thornhill, K. L., II; Shook, M.; Winstead, E.; Ziemba, L. D.; Bulzan, D. L.; Brown, A.; Beaton, B.; Schlager, H.

    2014-12-01

    Although the emission performance of gas-turbine engines burning renewable aviation fuels have been thoroughly documented in recent ground-based studies, there is still great uncertainty regarding how the fuels effect aircraft exhaust composition and contrail formation at cruise altitudes. To fill this information gap, the NASA Aeronautics Research Mission Directorate sponsored the ACCESS flight series to make detailed measurements of trace gases, aerosols and ice particles in the near-field behind the NASA DC-8 aircraft as it burned either standard petroleum-based fuel of varying sulfur content or a 50:50 blend of standard fuel and a hydro-treated esters and fatty acid (HEFA) jet fuel produced from camelina plant oil. ACCESS 1, conducted in spring 2013 near Palmdale CA, focused on refining flight plans and sampling techniques and used the instrumented NASA Langley HU-25 aircraft to document DC-8 emissions and contrails on five separate flights of ~2 hour duration. ACCESS 2, conducted from Palmdale in May 2014, engaged partners from the Deutsches Zentrum für Luft- und Raumfahrt (DLR) and National Research Council-Canada to provide additional scientific expertise and sampling aircraft (Falcon 20 and CT-133, respectively) with more extensive trace gas, particle, or air motion measurement capability. Eight, muliti-aircraft research flights of 2 to 4 hour duration were conducted to document the emissions and contrail properties of the DC-8 as it 1) burned low sulfur Jet A, high sulfur Jet A or low sulfur Jet A/HEFA blend, 2) flew at altitudes between 6 and 11 km, and 3) operated its engines at three different fuel flow rates. This presentation further describes the ACCESS flight experiments, examines fuel type and thrust setting impacts on engine emissions, and compares cruise-altitude observations with similar data acquired in ground-test venues.

  13. Incinerator performance: effects of changes in waste input and furnace operation on air emissions and residues.

    PubMed

    Astrup, Thomas; Riber, Christian; Pedersen, Anne Juul

    2011-10-01

    Waste incineration can be considered a robust technology for energy recovery from mixed waste. Modern incinerators are generally able to maintain relatively stable performance, but changes in waste input and furnace operation may affect emissions. This study investigated how inorganic air emissions and residue composition at a full-scale incinerator were affected by known additions of specific waste materials to the normal municipal solid waste (MSW) input. Six individual experiments were carried out (% ww of total waste input): NaCl (0.5%), shoes (1.6%), automobile shredder waste (14%), batteries (0.5%), poly(vinyl chloride) (5.5%) and chromate-cupper-arsenate impregnated wood (11%). Materials were selected based on chemical composition and potential for being included or excluded from the waste mix. Critical elements in the waste materials were identified based on comparison with six experiments including 'as-large-as-possible' changes in furnace operation (oxygen levels, air supply and burnout level) only using normal MSW as input. The experiments showed that effects from the added waste materials were significant in relation to: air emissions (in particular As, Cd, Cr, Hg, Sb), element transfer coefficients, and residue composition (As, Cd, Cl, Cr, Cu, Hg, Mo, Ni, Pb, S, Sb, Zn). Changes in furnace operation could not be directly linked to changes in emissions and residues. The results outlined important elements in waste which should be addressed in relation to waste incinerator performance. Likely ranges of element transfer coefficients were provided as the basis for sensitivity analysis of life-cycle assessment (LCA) results involving waste incinerator technologies.

  14. Alternative-Fuel Effects on Contrails & Cruise Emissions (ACCESS-2) Flight Experiment

    NASA Technical Reports Server (NTRS)

    Anderson, Bruce E.

    2015-01-01

    Although the emission performance of gas-turbine engines burning renewable aviation fuels have been thoroughly documented in recent ground-based studies, there is still great uncertainty regarding how the fuels effect aircraft exhaust composition and contrail formation at cruise altitudes. To fill this information gap, the NASA Aeronautics Research Mission Directorate sponsored the ACCESS flight series to make detailed measurements of trace gases, aerosols and ice particles in the near-field behind the NASA DC-8 aircraft as it burned either standard petroleum-based fuel of varying sulfur content or a 50:50 blend of standard fuel and a hydro-treated esters and fatty acid (HEFA) jet fuel produced from camelina plant oil. ACCESS 1, conducted in spring 2013 near Palmdale CA, focused on refining flight plans and sampling techniques and used the instrumented NASA Langley HU-25 aircraft to document DC-8 emissions and contrails on five separate flights of approx.2 hour duration. ACCESS 2, conducted from Palmdale in May 2014, engaged partners from the Deutsches Zentrum fuer Luft- und Raumfahrt (DLR) and National Research Council-Canada to provide additional scientific expertise and sampling aircraft (Falcon 20 and CT-133, respectively) with more extensive trace gas, particle, or air motion measurement capability. Eight, muliti-aircraft research flights of 2 to 4 hour duration were conducted to document the emissions and contrail properties of the DC-8 as it 1) burned low sulfur Jet A, high sulfur Jet A or low sulfur Jet A/HEFA blend, 2) flew at altitudes between 6 and 11 km, and 3) operated its engines at three different fuel flow rates. This presentation further describes the ACCESS flight experiments, examines fuel type and thrust setting impacts on engine emissions, and compares cruise-altitude observations with similar data acquired in ground tests.

  15. Effects of animal activity and air temperature on methane and ammonia emissions from a naturally ventilated building for dairy cows

    NASA Astrophysics Data System (ADS)

    Ngwabie, N. M.; Jeppsson, K.-H.; Gustafsson, G.; Nimmermark, S.

    2011-12-01

    Knowledge of how different factors affect gas emissions from animal buildings can be useful for emission prediction purposes and for the improvement of emission abatement techniques. In this study, the effects of dairy cow activity and indoor air temperature on gas emissions were examined. The concentrations of CH 4, NH 3, CO 2 and N 2O inside and outside a dairy cow building were measured continuously between February and May together with animal activity and air temperature. The building was naturally ventilated and had a solid concrete floor which sloped towards a central urine gutter. Manure was scraped from the floor once every hour in the daytime and once every second hour at night into a partly covered indoor pit which was emptied daily at 6 a.m. and at 5 p.m. Gas emissions were calculated from the measured gas concentrations and ventilation rates estimated by the CO 2 balance method. The animal activity and emission rates of CH 4 and NH 3 showed significant diurnal variations with two peaks which were probably related to the feeding routine. On an average day, CH 4 emissions ranged from 7 to 15 g LU -1 h -1 and NH 3 emissions ranged from 0.4 to 1.5 g LU -1 h -1 (1 LU = 500 kg animal weight). Mean emissions of CH 4 and NH 3 were 10.8 g LU -1 h -1 and 0.81 g LU -1 h -1, respectively. The NH 3 emissions were comparable to emissions from tied stall buildings and represented a 4% loss in manure nitrogen. At moderate levels, temperature seems to affect the behaviour of dairy cows and in this study where the daily indoor air temperature ranged from about 5 up to about 20 °C, the daily activity of the cows decreased with increasing indoor air temperature ( r = -0.78). Results suggest that enteric fermentation is the main source of CH 4 emissions from systems of the type in this study, while NH 3 is mainly emitted from the manure. Daily CH 4 emissions increased significantly with the activity of the cows ( r = 0.61) while daily NH 3 emissions increased

  16. The effect of lactation length on greenhouse gas emissions from the national dairy herd.

    PubMed

    Wall, E; Coffey, M P; Pollott, G E

    2012-11-01

    Many governments have signed up to greenhouse gas emission (GHGE) reduction programmes under their national climate change obligations. Recently, it has been suggested that the use of extended lactations in dairy herds could result in reduced GHGE. Dairy GHGE were modelled on a national basis and the model was used to compare emissions from lactations of three different lengths (305, 370 and 440 days), and a current 'base' scenario on the basis of maintaining current milk production levels. In addition to comparing GHGE from the average 'National Herd' under these scenarios, results were used to investigate how accounting for lactations of different lengths might alter the estimation of emissions calculated from the National Inventory methodology currently recommended by Intergovernmental Panel on Climate Change. Data for the three lactation length scenarios were derived from nationally recorded dairy performance information and used in the GHGE model. Long lactations required fewer milking cows and replacements to maintain current milk yield levels than short ones, but GHGEs were found to rise from 1214 t of CO2 equivalent (CE)/farm per year for lactations of 305 days to 1371 t CE/farm per year for 440-day lactations. This apparent anomaly can be explained by the less efficient milk production (kg milk produced per kg cow weight) found in later lactation, a more pronounced effect in longer lactations. The sensitivity of the model to changes in replacement rate, persistency and level of milk yield was investigated. Changes in the replacement rate from 25% to 20% and in persistency by −10% to +20% resulted in very small changes in GHGE. Differences in GHGE due to the level of milk yield were much more dramatic with animals in the top 10% for yield, producing about 25% less GHGE/year than the average animal. National Inventory results were investigated using a more realistic spread of lactation lengths than recommended for such calculations using emissions

  17. Updating soil CO2 emission experiments to assess climate change effects and extracellular soil respiration

    NASA Astrophysics Data System (ADS)

    Vidal Vazquez, Eva; Paz Ferreiro, Jorge

    2014-05-01

    Experimental work is an essential component in training future soil scientists. Soil CO2 emission is a key issue because of the potential impacts of this process on the greenhouse effect. The amount of organic carbon stored in soils worldwide is about 1600 gigatons (Gt) compared to 750 Gt in the atmosphere mostly in the form of CO2. Thus, if soil respiration increased slightly so that just 10% of the soil carbon pool was converted to CO2, atmospheric CO2 concentrations in the atmosphere could increase by one-fifth. General circulation model predictions indicate atmosphere warming between 2 and 5°C (IPCC 2007) and precipitation changes ranging from about -15 to +30%. Traditionally, release of CO2 was thought to occur only in an intracellular environment; however, recently CO2 emissions have been in irradiated soil, in the absence of microorganisms (Maire et al., 2013). Moreover, soil plays a role in the stabilization of respiration enzymes promoting CO2 release after microorganism death. Here, we propose to improve CO2 emission experiments commonly used in soil biology to investigate: 1) effects of climatic factors on soil CO2 emissions, and 2) rates of extracellular respiration in soils and how these rates are affected by environmental factors. Experiment designed to assess the effect of climate change can be conducted either in field conditions under different ecosystems (forest, grassland, cropland) or in a greenhouse using simple soil chambers. The interactions of climate change in CO2 emissions are investigated using climate-manipulation experiment that can be adapted to field or greenhouse conditions (e.g. Mc Daniel et al., 2013). The experimental design includes a control plot (without soil temperature and rain manipulation) a warming treatment as well as wetting and/or drying treatments. Plots are warmed to the target temperature by procedures such as infrared heaters (field) or radiant cable (greenhouse). To analyze extracellular respiration, rates of CO2

  18. Vehicle-based road dust emission measurement (III):. effect of speed, traffic volume, location, and season on PM 10 road dust emissions in the Treasure Valley, ID

    NASA Astrophysics Data System (ADS)

    Etyemezian, V.; Kuhns, H.; Gillies, J.; Chow, J.; Hendrickson, K.; McGown, M.; Pitchford, M.

    The testing re-entrained aerosol kinetic emissions from roads (TRAKER) road dust measurement system was used to survey more than 400 km of paved roads in southwestern Idaho during 3-week sampling campaigns in winter and summer, 2001. Each data point, consisting of a 1-s measurement of particle light scattering sampled behind the front tire, was associated with a link (section of road) in the traffic demand model network for the Treasure Valley, ID. Each link was in turn associated with a number of characteristics including posted speed limit, vehicle kilometers traveled (vkt), road class (local/residential, collector, arterial, and interstate), county, and land use (urban vs. rural). Overall, the TRAKER-based emission factors based on location, setting, season, and speed spanned a narrow range from 3.6 to 8.0 g/vkt. Emission factors were higher in winter compared to summer, higher in urban areas compared to rural, and lower for roads with fast travel speeds compared to slower roads. The inherent covariance between traffic volume and traffic speed obscured the assessment of the effect of traffic volume on emission potentials. Distance-based emission factors expressed in grams per kilometer traveled (g/vkt) for roads with low travel speeds (˜11 m/s residential roads) compared to those with high travel speeds (˜25 m/s interstates) were higher (5.2 vs. 3.0 g/vkt in summer and 5.9 vs. 4.9 g/vkt in winter). However, emission potentials which characterize the amount of suspendable material on a road were substantially higher on roads with low travel speeds (0.71 vs. 0.13 g/vkt/(m/s) in summer and 0.78 vs. 0.21 g/vkt/(m/s) in winter). This suggested that while high speed roads are much cleaner (factor of 5.4 in summer), on a vehicle kilometer traveled basis, emissions from high and low speed roads are of the same order. Emission inventories based on the TRAKER method, silt loadings obtained during the field study, and US EPA's AP-42 default values of silt loading were

  19. The Atmospheric Effects of HSCT Emissions Simulated by a 3-Wave Interactive Model. Appendix N

    NASA Technical Reports Server (NTRS)

    Shia, R.-L.; Ko, M. K. W.; Sze, N. D.

    1999-01-01

    An interactive model which couples a semi-spectral dynamical model, a radiative transfer code and a two-dimensional chemistry transport model (2-D CTM), is used to assess the atmospheric effects of the High-Speed Civil Transport (HSCT) engine emissions. The residual mean meridional circulation, the zonal-mean temperature and the eddy diffusion coefficients are calculated using zonal means and three longest zonal waves of dynamical variables integrated in the semi-spectral dynamical model. They are used in the 2-D CTM to simulate the distribution of trace gases in the atmosphere. The simulated ozone is sent to the radiative transfer code to calculate the heating rates, which drive the dynamics. This radiative coupling connects the dynamical and photochemical processes and creates feedback when the atmosphere is perturbed. It is found that in most areas the ozone depletion caused by HSCT emissions calculated using the 3-wave model has the features similar to, but with significantly larger magnitude than that calculated by the AER 2-D CTM with prescribed transport parameters and temperature. The difference is mostly due to the differences in the circulation in the two models. The radiative feedback effects are investigated by comparing the ozone depletion calculated with the baseline dynamics and with the dynamics perturbed by the HSCT emissions. The feedback through changes in the residual mean meridional circulation and the eddy diffusion coefficients has moderate effects on the simulated ozone depletion. It reduced the ozone depletion by 20-30% in northern mid and high-latitudes. However, the feedback through changes in the zonal- mean temperature is negligible.

  20. Effects of the dynamics of droplet-based laser-produced plasma on angular extreme ultraviolet emission profile

    SciTech Connect

    Giovannini, Andrea Z.; Abhari, Reza S.

    2014-05-12

    The emission distribution of extreme ultraviolet (EUV) radiation from droplet targets is dependent on the dynamics of the laser-produced plasma. The EUV emission is measured on a 2% bandwidth centered at 13.5 nm (in-band). The targets of the laser are small (sub-50 μm) tin droplets, and the in-band emission distribution is measured for different laser irradiances and droplet sizes at various angular positions. Larger droplets lead to a faster decay of EUV emission at larger angles with respect to the laser axis. A decrease in laser irradiance has the opposite effect. The measurements are used together with an analytical model to estimate plume dynamics. Additionally, the model is used to estimate EUV emission distribution for a desired droplet diameter and laser irradiance.

  1. Experimental and theoretical studies of laser-induced breakdown spectroscopy emission from iron oxide: Studies of atmospheric effects

    NASA Astrophysics Data System (ADS)

    Colgan, J.; Barefield, J. E.; Judge, E. J.; Campbell, K.; Johns, H. M.; Kilcrease, D. P.; McInroy, R.; Clegg, S. M.

    2016-08-01

    We report on a comprehensive study of the emission spectra from laser-induced breakdown spectroscopy (LIBS) measurements on iron oxide. Measurements have been made of the emission from Fe2O3 under atmospheres of air, He, and Ar, and at different atmospheric pressures. The effect of varying the time delay of the measurement is also explored. Theoretical calculations were performed to analyze the plasma conditions and find that a reasonably consistent picture of the change in plasma temperature and density for different atmospheric conditions can be reached. We also investigate the sensitivity of the OI 777 nm emission lines to the plasma conditions, something that has not been explored in detail in the previous work. Finally, we also show that LIBS can be used to differentiate between FeO and Fe2O3 by examining the ratio of the intensities of selected Fe emission to O emission lines.

  2. Coupling of soil solarization and reduced rate fumigation: effects on methyl iodide emissions from raised beds under field conditions.

    PubMed

    Ashworth, Daniel J; Yates, Scott R; Luo, Lifang; Lee, Sang R; Xuan, Richeng

    2013-12-26

    Using field plots, we studied the effect on methyl iodide (MeI) emissions of coupling soil solarization (passive and active) and reduced rate fumigation (70% of a standard fumigation) in raised beds under virtually impermeable film (VIF). The results showed that for the standard fumigation and the passive solarization + fumigation treatments, emissions from the nontarped furrow were very high (∼50%). Emissions from the bed top and sidewall of these treatments were relatively low but were increased in the latter due to the longer environmental exposure of the VIF covering with the coupled approach (increased tarp permeability). Overall, this approach offered no advantage over fumigation-only in terms of emission reduction. With active solarization + fumigation, the large application of hot water during solarization apparently led to severely limited diffusion causing very low total emissions (<1%). Although this suggests a benefit in terms of air quality, a lack of diffusion could limit the pesticidal efficacy of the treatment.

  3. Effects of reaction conditions on the emission behaviors of arsenic, cadmium and lead during sewage sludge pyrolysis.

    PubMed

    Han, Hengda; Hu, Song; Syed-Hassan, Syed Shatir A; Xiao, Yiming; Wang, Yi; Xu, Jun; Jiang, Long; Su, Sheng; Xiang, Jun

    2017-03-31

    Sewage sludge is an important class of bioresources whose energy content could be exploited using pyrolysis technology. However, some harmful trace elements in sewage sludge can escape easily to the gas phase during pyrolysis, increasing the potential of carcinogenic material emissions to the atmosphere. This study investigates emission characteristics of arsenic, cadmium and lead under different pyrolysis conditions for three different sewage sludge samples. The increased temperature (within 723-1123K) significantly promoted the cadmium and lead emissions, but its influence on arsenic emission was not pronounced. The releasing rate order of the three trace elements is volatile arsenic compounds>cadmium>lead in the beginning of pyrolysis. Fast heating rates promoted the emission of trace elements for the sludge containing the highest amount of ash, but exhibited an opposite effect for other studied samples. Overall, the high ash sludge released the least trace elements almost under all reaction conditions.

  4. EFFECTS OF ALFVEN WAVES ON ELECTRON CYCLOTRON MASER EMISSION IN CORONAL LOOPS AND SOLAR TYPE I RADIO STORMS

    SciTech Connect

    Zhao, G. Q.; Chen, L.; Wu, D. J.; Yan, Y. H.

    2013-06-10

    Solar type I radio storms are long-lived radio emissions from the solar atmosphere. It is believed that these type I storms are produced by energetic electrons trapped within a closed magnetic structure and are characterized by a high ordinary (O) mode polarization. However, the microphysical nature of these emissions is still an open problem. Recently, Wu et al. found that Alfven waves (AWs) can significantly influence the basic physics of wave-particle interactions by modifying the resonant condition. Taking the effects of AWs into account, this work investigates electron cyclotron maser emission driven by power-law energetic electrons with a low-energy cutoff distribution, which are trapped in coronal loops by closed solar magnetic fields. The results show that the emission is dominated by the O mode. It is proposed that this O mode emission may possibly be responsible for solar type I radio storms.

  5. Edge effect enhanced photo-thermionic emission from a carbon nanotubes array

    NASA Astrophysics Data System (ADS)

    Li, Chi; Li, Zhenjun; Chen, Ke; Bai, Bing; Dai, Qing

    2017-02-01

    Employing optical field enhancement at the edges of the nanostructures, an enhanced photo-thermionic emission (PTE) was obtained from a well-defined carbon nanotube (CNT) cluster array. Compared with the un-patterned carbon nanotube film, the PTE from the CNT cluster array was enhanced 10 times at the same laser intensity. The concept was proved by the computer simulation as well. We believe that an edge effect enhanced CNT PTE emitter is of great potential for application in next-generation portable and inexpensive vacuum electronic devices.

  6. Health Effects of Subchronic Inhalation of Simulated Downwind Coal Combustion Emissions

    SciTech Connect

    Joe Mauderly

    2009-01-07

    The purpose of this project was to conduct a comprehensive laboratory-based evaluation of selected respiratory and cardiac health hazards of subchronic (up to 6 months) inhalation of simulated key components of 'downwind plume' emissions of coal combustion. This project was performed as an integral part of a joint government-industry program termed the 'National Environmental Respiratory Center' (NERC), which is aimed at disentangling the roles of different physical-chemical air pollutants and their sources in the health effects associated statistically with air pollution. The characterization of the exposure atmosphere and the health assays were identical to those employed in the NERC protocols used to evaluate other pollution source emissions, such as diesel, gasoline, and wood combustion. The project had two phases, each encompassing multiple tasks. Guidelines for the composition of the exposure atmosphere were set by consensus of an expert workshop. Development of the capability to generate the exposure atmosphere and pilot studies of the comparative exposure composition using two coal types were accomplished in Phase 1. In Phase 2, the toxicological study was conducted using Powder River Basin Sub-bituminous coal. NETL provided 50% support for the work in Phase 1 and had intended to provide 20% support for the work in Phase 2. Phase 1 is completed and Phase 2 is in the final stages. All animal exposures were completed without incident, and the composition of the exposure atmospheres met the targets. All of the health sample collections are completed, but some samples remain to be analyzed. Data summaries and final statistical analysis of results remain to be completed. The goal is to submit all publications before the end of FY-08. Repeated exposure to simulated downwind coal emissions caused some significant health effects, but the number of effects tended to be fewer than those caused by the other NERC exposures (diesel and gasoline emissions and hardwood

  7. Plasma wave oscillations in nanometer field effect transistors for terahertz detection and emission.

    PubMed

    Knap, W; Teppe, F; Dyakonova, N; Coquillat, D; Lusakowski, J

    2008-09-24

    The channel of a field effect transistor can act as a resonator for plasma waves propagating in a two-dimensional electron gas. The plasma frequency increases with reduction of the channel length and can reach the terahertz (THz) range for nanometer size transistors. Recent experimental results show these transistors can be potential candidates for a new class of THz detectors and emitters. This work gives an overview of our recent relevant experimental results. We also outline unresolved problems and questions concerning THz detection and emission by nanometer transistors.

  8. Asymmetries in the motional Stark effect emission on the DIII-D tokamak

    NASA Astrophysics Data System (ADS)

    Victor, B. S.; Holcomb, C. T.; Allen, S. L.; Meyer, W. H.; Makowski, M. A.; Thorman, A.

    2016-11-01

    Spectrometer measurements and filter upgrades to a motional Stark effect polarimeter measuring the outer half-radius of the DIII-D tokamak helped to identify asymmetries in the polarization angle of Stark-split emission. The measured polarization angle of the π components differs and is not orthogonal to the σ component. These differences persist over a range of densities and with low levels of background light. It is suggested that the difference in the polarization angle between components is from a change in the ellipticity of the emitted light across the Stark components coupled with imperfect polarization preservation from an in-vessel mirror.

  9. Methods for correcting microwave scattering and emission measurements for atmospheric effects

    NASA Technical Reports Server (NTRS)

    Komen, M. (Principal Investigator)

    1975-01-01

    The author has identified the following significant results. Algorithms were developed to permit correction of scattering coefficient and brightness temperature for the Skylab S193 Radscat for the effects of cloud attenuation. These algorithms depend upon a measurement of the vertically polarized excess brightness temperature at 50 deg incidence angle. This excess temperature is converted to an equivalent 50 deg attenuation, which may then be used to estimate the horizontally polarized excess brightness temperature and reduced scattering coefficient at 50 deg. For angles other than 50 deg, the correction also requires use of the variation of emissivity with salinity and water temperature.

  10. The effects of soil moisture, surface roughness, and vegetation on L-band emission and backscatter

    NASA Technical Reports Server (NTRS)

    Wang, James R.; Shiue, J. C.; Engman, Edwin T.; Schmugge, Thomas J.; Mo, Tsan

    1987-01-01

    Measurements performed with SIR-B at 1.28 GHz and an airborne multiple-beam push-broom radiometer at 1.4 GHz over agricultural fields near Fresno, California are examined. A theoretical model (Kirchhoff approximation) was used to assess the effects of surface roughness and vegetation (alfalfa and lettuce) with respect to the responses of microwave emission and backscatter to soil-moisture variations. It is found that the surface roughness plays a dominant role compared to the vegetation cover in the microwave backscatter.

  11. Asymmetries in the motional Stark effect emission on the DIII-D tokamak.

    PubMed

    Victor, B S; Holcomb, C T; Allen, S L; Meyer, W H; Makowski, M A; Thorman, A

    2016-11-01

    Spectrometer measurements and filter upgrades to a motional Stark effect polarimeter measuring the outer half-radius of the DIII-D tokamak helped to identify asymmetries in the polarization angle of Stark-split emission. The measured polarization angle of the π components differs and is not orthogonal to the σ component. These differences persist over a range of densities and with low levels of background light. It is suggested that the difference in the polarization angle between components is from a change in the ellipticity of the emitted light across the Stark components coupled with imperfect polarization preservation from an in-vessel mirror.

  12. State-level renewable portfolio standards: Evaluating their effectiveness in increasing renewable electricity generation and reducing carbon emissions

    NASA Astrophysics Data System (ADS)

    Denneny, Matthew J.

    The renewable portfolio standard (RPS) is a key state-level policy instrument meant to encourage renewable energy development and address climate change by mandating increased electricity generation from low-carbon renewable sources. In analyzing the effectiveness of RPS policies, I hypothesize that these policies should increase renewable electricity generation and reduce carbon dioxide emissions from electricity generation. Additionally, I hypothesize that more stringent RPS policies should allow for greater increases in renewable energy generation and larger declines in CO2 emissions. To test these hypotheses, I use pooled and fixed effects models to examine how RPS policies play a role in affecting renewable electricity generation and CO 2 emissions. My results suggest that these policies increase electricity generation from renewable sources and that the stringency of these policies matters. However, the results are mixed in regard to their effectiveness in reducing CO2 emissions. These findings suggest that RPS policies as they are now may not be the best way to reduce CO2 emissions. Other policies that more directly target emissions may be necessary for states to see the emissions reductions they desire.

  13. Effect of plastic tarps over raised-beds and potassium thiosulfate in furrows on chloropicrin emissions from drip fumigated fields.

    PubMed

    Qin, Ruijun; Gao, Suduan; McDonald, Jason A; Ajwa, Husein; Shem-Tov, Shachar; Sullivan, David A

    2008-06-01

    Plastic tarps are commonly used in raised bed strawberry production to minimize emissions of preplant soil fumigants and are left in place throughout the growing season as part of the standard cultural practices. Soil amendments with chemicals such as thiosulfate (S2O3(2-)) can reduce fumigant emissions. A field study was conducted near Santa Maria, CA to determine the effects of low density polyethylene (LDPE) and virtually impermeable film (VIF) over raised-beds and applying potassium thiosulfate (KTS) in furrows on reducing chloropicrin (CP) emissions from a strawberry field. Four fields (or treatments) were tested with 224 kg ha(-1) CP drip-applied threecm under the soil surface. The CP flux from bed tops and furrows and gas-phase concentrations under the tarps were monitored for five d. The CP emission flux and concentration under tarp were highest immediately following application. Diurnal temperature change affected CP concentration and emission fluxes (higher values during the day and lower at night). Slightly higher CP cumulative emission occurred using LDPE tarp (19%) compared to VIF (17%). Normalized flux (CP emission flux from the beds divided by CP concentration under the tarp) being estimated from field measurement was slightly higher for LDPE than VIF indicating different tarp permeability in the field. Because of extremely low emissions from the furrows (<0.2% of total emission loss), KTS application to furrow treatments did not show further emission reductions than non-KTS treatments. This indicates that emission reduction should focus on the tarp above raised-beds when fumigant was drip-applied near bed-surface.

  14. Effects of particulate oxidation catalyst on unregulated pollutant emission and toxicity characteristics from heavy-duty diesel engine.

    PubMed

    Feng, Xiangyu; Ge, Yunshan; Ma, Chaochen; Tan, Jianwei

    2015-01-01

    To evaluate the effects of particulate oxidation catalyst (POC) on unregulated pollutant emission and toxicity characteristics, polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), soot, soluble organic fractions (SOF) and sulphate emissions emitted from a heavy-duty diesel engine retrofitted with a POC were investigated on a diesel bench. The particulate matter (PM) in the exhaust was collected by Teflon membrane, and the PAHs and VOCs were analysed by a gas chromatography/mass spectrometer (GC/MS). The results indicate that the POC exhibits good performance on the emission control of VOCs, PAHs and PM. The POC and the diesel particulate filters (DPF) both show a good performance on reducing the VOCs emission. Though the brake-specific emission (BSE) reductions of the total PAHs by the POC were lower than those by the DPF, the POC still removed almost more than 50% of the total PAHs emission. After the engine was retrofitted with the POC, the reductions of the PM mass, SOF and soot emissions were 45.2-89.0%, 7.8-97.7% and 41.7-93.3%, respectively. The sulphate emissions decreased at low and medium loads, whereas at high load, the results were contrary. The PAHs emissions were decreased by 32.4-69.1%, and the contributions of the PAH compounds were affected by the POC, as well as by load level. The benzo[a]pyrene equivalent (BaPeq) of PAHs emissions were reduced by 35.9-97.6% with the POC. The VOCs emissions were reduced by 21.8-94.1% with the POC, and the reduction was more evident under high load.

  15. Cost-effectiveness of controlling emissions for various alternative-fuel vehicle types, with vehicle and fuel price subsidies estimated on the basis of monetary values of emission reductions

    SciTech Connect

    Wang, M.Q.

    1993-12-31

    Emission-control cost-effectiveness is estimated for ten alternative-fuel vehicle (AFV) types (i.e., vehicles fueled with reformulated gasoline, M85 flexible-fuel vehicles [FFVs], M100 FFVs, dedicated M85 vehicles, dedicated M100 vehicles, E85 FFVS, dual-fuel liquefied petroleum gas vehicles, dual-fuel compressed natural gas vehicles [CNGVs], dedicated CNGVs, and electric vehicles [EVs]). Given the assumptions made, CNGVs are found to be most cost-effective in controlling emissions and E85 FFVs to be least cost-effective, with the other vehicle types falling between these two. AFV cost-effectiveness is further calculated for various cases representing changes in costs of vehicles and fuels, AFV emission reductions, and baseline gasoline vehicle emissions, among other factors. Changes in these parameters can change cost-effectiveness dramatically. However, the rank of the ten AFV types according to their cost-effectiveness remains essentially unchanged. Based on assumed dollars-per-ton emission values and estimated AFV emission reductions, the per-vehicle monetary value of emission reductions is calculated for each AFV type. Calculated emission reduction values ranged from as little as $500 to as much as $40,000 per vehicle, depending on AFV type, dollar-per-ton emission values, and baseline gasoline vehicle emissions. Among the ten vehicle types, vehicles fueled with reformulated gasoline have the lowest per-vehicle value, while EVs have the highest per-vehicle value, reflecting the magnitude of emission reductions by these vehicle types. To translate the calculated per-vehicle emission reduction values to individual AFV users, AFV fuel or vehicle price subsidies are designed to be equal to AFV emission reduction values. The subsidies designed in this way are substantial. In fact, providing the subsidies to AFVs would change most AFV types from net cost increases to net cost decreases, relative to conventional gasoline vehicles.

  16. Effects of exomoon’s magnetic field on generation of radio emissions

    NASA Astrophysics Data System (ADS)

    Griffith, John; Noyola, Joaquin; Satyal, Suman; Musielak, Zdzislaw E.

    2017-01-01

    In the recent work by Noyola et al. (2014, 2016), a novel technique of detection of exomoons through the radio emissions produced by the magnetic field interactions between exoplanet-exomoon pair is emulated based upon the processes occurring in the Jupiter-Io system. Their calculations have shown that the radio signal from the distant extra-solar planetary systems is detectable by current technology provided that the systems emanating the radio waves are relatively closer, have some form of atmosphere, and have larger exomoons. In this work, we explore the effect of exomoon’s magnetic field on the radio emission processes by considering a hypothetical magnetic exomoon and re-calculating the resulting radio flux. Then, a limit to the exomoon’s magnetic field is proposed based on the signal amplification versus the dampening effect the magnetic field induces on the secondary conditions such as the containment of ions within the exomoon’s magnetic field and the effect of the plasma torus density that co-orbits with the moon. The energy from the exomoon’s magnetic field is expected to amplify the radio signal, hence increasing the probability of detection of the first exomoons.

  17. Negative space charge effects in photon-enhanced thermionic emission solar converters

    SciTech Connect

    Segev, G.; Weisman, D.; Rosenwaks, Y.; Kribus, A.

    2015-07-06

    In thermionic energy converters, electrons in the gap between electrodes form a negative space charge and inhibit the emission of additional electrons, causing a significant reduction in conversion efficiency. However, in Photon Enhanced Thermionic Emission (PETE) solar energy converters, electrons that are reflected by the electric field in the gap return to the cathode with energy above the conduction band minimum. These electrons first occupy the conduction band from which they can be reemitted. This form of electron recycling makes PETE converters less susceptible to negative space charge loss. While the negative space charge effect was studied extensively in thermionic converters, modeling its effect in PETE converters does not account for important issues such as this form of electron recycling, nor the cathode thermal energy balance. Here, we investigate the space charge effect in PETE solar converters accounting for electron recycling, with full coupling of the cathode and gap models, and addressing conservation of both electric and thermal energy. The analysis shows that the negative space charge loss is lower than previously reported, allowing somewhat larger gaps compared to previous predictions. For a converter with a specific gap, there is an optimal solar flux concentration. The optimal solar flux concentration, the cathode temperature, and the efficiency all increase with smaller gaps. For example, for a gap of 3 μm the maximum efficiency is 38% and the optimal flux concentration is 628, while for a gap of 5 μm the maximum efficiency is 31% and optimal flux concentration is 163.

  18. Effect of water injection on nitric oxide emissions of a gas turbine combustor burning natural gas fuel

    NASA Technical Reports Server (NTRS)

    Marchionna, N. R.; Diehl, L. A.; Trout, A. M.

    1973-01-01

    The effect of direct water injection on the exhaust gas emissions of a turbojet combustor burning natural gas fuel was investigated. The results are compared with the results from similar tests using ASTM Jet-A fuel. Increasing water injection decreased the emissions of oxides of nitrogen (NOX) and increased the emissions of carbon monoxide and unburned hydrocarbons. The greatest percentage decrease in NOX with increasing water injection was at the lowest inlet-air temperature tested. The effect of increasing inlet-air temperature was to decrease the effect of the water injection. The reduction in NOX due to water injection was almost identical to the results obtained with Jet-A fuel. However, the emission indices of unburned hydrocarbons, carbon monoxide, and percentage nitric oxide in NOX were not.

  19. Effects of fuel properties on white smoke emission from the latest heavy-duty DI diesel engine

    SciTech Connect

    Tahara, Yoshihiro; Akasaka, Yukio

    1995-12-31

    The effects of fuel properties on white smoke emission from the latest DI diesel engine were investigated with a new type of white smoke meter. The new smoke meter could distinguish fuel effects on smoke much more than the conventional PHS meter. The repeatability of the smoke meter was better than that of the PHS meter. Cetane number was the dominant factor for smoke emission. Distillation temperature and composition also affected emission. A nitrate type cetane improver was effective for reducing emission. White smoke was analyzed with GC and HPLC and compounds in white smoke from low cetane number fuel were found almost the same as in fuel. But those from high cetane number fuel consisted of compounds in fuel and many combustion products.

  20. Effects of water-saving irrigation on emissions of greenhouse gases and prokaryotic communities in rice paddy soil.

    PubMed

    Ahn, Jae-Hyung; Choi, Min-Young; Kim, Byung-Yong; Lee, Jong-Sik; Song, Jaekyeong; Kim, Gun-Yeob; Weon, Hang-Yeon

    2014-08-01

    The effects of water-saving irrigation on emissions of greenhouse gases and soil prokaryotic communities were investigated in an experimental rice field. The water layer was kept at 1-2 cm in the water-saving (WS) irrigation treatment and at 6 cm in the continuous flooding (CF) irrigation treatment. WS irrigation decreased CH(4) emissions by 78 % and increased N(2)O emissions by 533 %, resulting in 78 % reduction of global warming potential compared to the CF irrigation. WS irrigation did not affect the abundance or phylogenetic distribution of bacterial/archaeal 16S rRNA genes and the abundance of bacterial/archaeal 16S rRNAs. The transcript abundance of CH(4) emission-related genes generally followed CH(4) emission patterns, but the difference in abundance between mcrA transcripts and amoA/pmoA transcripts best described the differences in CH(4) emissions between the two irrigation practices. WS irrigation increased the relative abundance of 16S rRNAs and functional gene transcripts associated with Anaeromyxobacter and Methylocystis spp., suggesting that their activities might be important in emissions of the greenhouse gases. The N(2)O emission patterns were not reflected in the abundance of N(2)O emission-related genes and transcripts. We showed that the alternative irrigation practice was effective for mitigating greenhouse gas emissions from rice fields and that it did not affect the overall size and structure of the soil prokaryotic community but did affect the activity of some groups.

  1. Effects of straw incorporation along with microbial inoculant on methane and nitrous oxide emissions from rice fields.

    PubMed

    Liu, Gang; Yu, Haiyang; Ma, Jing; Xu, Hua; Wu, Qinyan; Yang, Jinghui; Zhuang, Yiqing

    2015-06-15

    Incorporation of straw together with microbial inoculant (a microorganism agent, accelerating straw decomposition) is being increasingly adopted in rice cultivation, thus its effect on greenhouse gas (GHG) emissions merits serious attention. A 3-year field experiment was conducted from 2010 to 2012 to investigate combined effect of straw and microbial inoculant on methane (CH4) and nitrous oxide (N2O) emissions, global warming potential (GWP) and greenhouse gas intensity (GHGI) in a rice field in Jurong, Jiangsu Province, China. The experiment was designed to have treatment NPK (N, P and K fertilizers only), treatment NPKS (NPK plus wheat straw), treatment NPKSR (NPKS plus Ruilaite microbial inoculant) and treatment NPKSJ (NPKS plus Jinkuizi microbial inoculant). Results show that compared to NPK, NPKS increased seasonal CH4 emission by 280-1370%, while decreasing N2O emission by 7-13%. When compared with NPKS, NPKSR and NPKSJ increased seasonal CH4 emission by 7-13% and 6-12%, respectively, whereas reduced N2O emission by 10-27% and 9-24%, respectively. The higher CH4 emission could be attributed to the higher soil CH4 production potential triggered by the combined application of straw and microbial inoculant, and the lower N2O emission to the decreased inorganic N content. As a whole, the benefit of lower N2O emission was completely offset by increased CH4 emission, resulting in a higher GWP for NPKSR (5-12%) and NPKSJ (5-11%) relative to NPKS. Due to NPKSR and NPKSJ increased rice grain yield by 3-6% and 2-4% compared to NPKS, the GHGI values for NPKS, NPKSR and NPKSJ were comparable. These findings suggest that incorporating straw together with microbial inoculant would not influence the radiative forcing of rice production in the terms of per unit of rice grain yield relative to the incorporation of straw alone.

  2. Evaluating the effects of China's pollution control on inter-annual trends and uncertainties of atmospheric mercury emissions

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Zhong, H.; Zhang, J.; Nielsen, C. P.

    2014-10-01

    China's atmospheric mercury (Hg) emissions of anthropogenic origin have been effectively restrained through the national policy of air pollution control. Improved methods based on available field measurements are developed to quantify the benefits of Hg abatement through various emission control measures. Those measures include increased use of flue gas desulfurization (FGD) and selective catalyst reduction (SCR) systems for power sector, precalciners with fabric filter (FF) for cement production, machinery coking with electrostatic precipitator (ESP) for iron and steel production, and advanced manufacturing technologies for nonferrous metal smelting. Declining trends in emissions factors for those sources are revealed, leading to a much slower growth of national total Hg emissions than that of energy and economy, from 679 in 2005 to 750 metric tons (t) in 2012. In particular, nearly half of emissions from the above-mentioned four types of sources are expected to be reduced in 2012, attributed to expansion of technologies with high energy efficiencies and air pollutant removal rates after 2005. The speciation of Hg emissions keeps stable for recent years, with the mass fractions of around 55, 39 and 6% for Hg0, Hg2+ and Hgp, respectively. The lower estimate of Hg emissions than previous inventories is supported by limited chemistry simulation work, but middle-to-long term observation on ambient Hg levels is further needed to justify the inter-annual trends of estimated Hg emissions. With improved implementation of emission controls and energy saving, 23% reduction in annual Hg emissions for the most optimistic case in 2030 is expected compared to 2012, with total emissions below 600 t. While Hg emissions are evaluated to be gradually constrained, increased uncertainties are quantified with Monte-Carlo simulation for recent years, particularly for power and certain industrial sources. The uncertainty of Hg emissions from coal-fired power plants, as an example

  3. Atmospheric pollution reduction effect and regional predicament: An empirical analysis based on the Chinese provincial NOx emissions.

    PubMed

    Ding, Lei; Liu, Chao; Chen, Kunlun; Huang, Yalin; Diao, Beidi

    2017-03-09

    Atmospheric pollution emissions have become a matter of public concern in recent years. However, most of the existing researches on NOx pollution are from the natural science and technology perspective, few studies have been conducted from an economic point, and regional differences have not been given adequate attention. This paper adopts provincial panel data from 2006 to 2013 and the LMDI model to analyze the key driving factors and regional dilemmas of NOx emissions. The results show that significant regional disparities still exit on NOx emissions and its reduction effect 27 provinces didn't accomplish their corresponding reduction targets. Economic development factor is the dominating driving factor of NOx emissions during the study period, while energy efficiency and technology improvement factors offset total NOx emissions in the majority of provinces. In addition, the industrial structure factor plays a more significant role in reducing the NOx emissions after 2011. Therefore, the government should consider all these factors as well as regional heterogeneity in developing appropriate pollution mitigating policies. It's necessary to change NOx emissions control attitude from original key areas control to divided-zone control, not only attaches great importance to the reduction of the original key areas, but also emphasizes the new potential hotspots with high NOx emissions.

  4. Effect of Simulated Heat Stress on Digestibility, Methane Emission and Metabolic Adaptability in Crossbred Cattle

    PubMed Central

    Yadav, Brijesh; Singh, Gyanendra; Wankar, Alok; Dutta, N.; Chaturvedi, V. B.; Verma, Med Ram

    2016-01-01

    The present experiment was conducted to evaluate the effect of simulated heat stress on digestibility and methane (CH4) emission. Four non-lactating crossbred cattle were exposed to 25°C, 30°C, 35°C, and 40°C temperature with a relative humidity of 40% to 50% in a climatic chamber from 10:00 hours to 15:00 hours every day for 27 days. The physiological responses were recorded at 15:00 hours every day. The blood samples were collected at 15:00 hours on 1st, 6th, 11th, 16th, and 21st days and serum was collected for biochemical analysis. After 21 days, fecal and feed samples were collected continuously for six days for the estimation of digestibility. In the last 48 hours gas samples were collected continuously to estimate CH4 emission. Heat stress in experimental animals at 35°C and 40°C was evident from an alteration (p<0.05) in rectal temperature, respiratory rate, pulse rate, water intake and serum thyroxin levels. The serum lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase activity and protein, urea, creatinine and triglyceride concentration changed (p<0.05), and body weight of the animals decreased (p<0.05) after temperature exposure at 40°C. The dry matter intake (DMI) was lower (p<0.05) at 40°C exposure. The dry matter and neutral detergent fibre digestibilities were higher (p<0.05) at 35°C compared to 25°C and 30°C exposure whereas, organic matter (OM) and acid detergent fibre digestibilities were higher (p<0.05) at 35°C than 40°C thermal exposure. The CH4 emission/kg DMI and organic matter intake (OMI) declined (p<0.05) with increase in exposure temperature and reached its lowest levels at 40°C. It can be concluded from the present study that the digestibility and CH4 emission were affected by intensity of heat stress. Further studies are necessary with respect to ruminal microbial changes to justify the variation in the digestibility and CH4 emission during differential heat stress. PMID

  5. Effect of Simulated Heat Stress on Digestibility, Methane Emission and Metabolic Adaptability in Crossbred Cattle.

    PubMed

    Yadav, Brijesh; Singh, Gyanendra; Wankar, Alok; Dutta, N; Chaturvedi, V B; Verma, Med Ram

    2016-11-01

    The present experiment was conducted to evaluate the effect of simulated heat stress on digestibility and methane (CH4) emission. Four non-lactating crossbred cattle were exposed to 25°C, 30°C, 35°C, and 40°C temperature with a relative humidity of 40% to 50% in a climatic chamber from 10:00 hours to 15:00 hours every day for 27 days. The physiological responses were recorded at 15:00 hours every day. The blood samples were collected at 15:00 hours on 1st, 6th, 11th, 16th, and 21st days and serum was collected for biochemical analysis. After 21 days, fecal and feed samples were collected continuously for six days for the estimation of digestibility. In the last 48 hours gas samples were collected continuously to estimate CH4 emission. Heat stress in experimental animals at 35°C and 40°C was evident from an alteration (p<0.05) in rectal temperature, respiratory rate, pulse rate, water intake and serum thyroxin levels. The serum lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase activity and protein, urea, creatinine and triglyceride concentration changed (p<0.05), and body weight of the animals decreased (p<0.05) after temperature exposure at 40°C. The dry matter intake (DMI) was lower (p<0.05) at 40°C exposure. The dry matter and neutral detergent fibre digestibilities were higher (p<0.05) at 35°C compared to 25°C and 30°C exposure whereas, organic matter (OM) and acid detergent fibre digestibilities were higher (p<0.05) at 35°C than 40°C thermal exposure. The CH4 emission/kg DMI and organic matter intake (OMI) declined (p<0.05) with increase in exposure temperature and reached its lowest levels at 40°C. It can be concluded from the present study that the digestibility and CH4 emission were affected by intensity of heat stress. Further studies are necessary with respect to ruminal microbial changes to justify the variation in the digestibility and CH4 emission during differential heat stress.

  6. Vehicle-based road dust emission measurement—Part II: Effect of precipitation, wintertime road sanding, and street sweepers on inferred PM 10 emission potentials from paved and unpaved roads

    NASA Astrophysics Data System (ADS)

    Kuhns, H.; Etyemezian, V.; Green, M.; Hendrickson, Karin; McGown, Michael; Barton, Kevin; Pitchford, Marc

    Testing Re-Entrained Kinetic Emissions from Roads (TRAKER) is a new technique to infer paved and unpaved road dust PM 10 emission potentials based on particulate matter (PM) measurements made onboard a moving vehicle. Light scattering instruments mounted in front and behind the vehicle's tires measure the differential particle concentration of dust suspended by the vehicle's tire in contact with the road surface. Through empirical regressions relating the differential concentration (i.e. TRAKER signal) with the vehicle speed and the downwind flux of PM 10 particles from the road, an equation is derived to infer the speed independent road dust emission potential from the measured TRAKER signal. Measurements from TRAKER offer a new perspective on the processes that affect road dust emissions. The system was used to investigate temporal changes in emission potentials from paved roads in both the winter and summer in the Treasure Valley in Southwest Idaho. During the 3-week wintertime sampling period, the residential road dust PM 10 emission potential decreased by ˜50%. Summertime PM 10 emission potentials were similar to those observed at the end of the winter sampling and showed no upward or downward trends. Wintertime unpaved road emissions increased consistently with the number of days since the last rainfall. Measurement of road dust emission potentials after road sanding on dry roads indicated a 75% increase in PM 10 emissions after 2.5 h. This effect was short lived and emission potentials returned to their pre-sanding levels within 8 h of the sand application. Street sweeping with mechanical and vacuum sweepers was found to offer no measurable reduction in PM 10 emission potentials. On several roads, the PM 10 emission potentials actually increased immediately after vacuum sweeping. Long term effects of street sweeping on road dust emissions were not evaluated as part of this study and may offer some overall reduction in PM emissions from paved roads.

  7. Determination of PM mass emissions from an aircraft turbine engine using particle effective density

    NASA Astrophysics Data System (ADS)

    Durdina, L.; Brem, B. T.; Abegglen, M.; Lobo, P.; Rindlisbacher, T.; Thomson, K. A.; Smallwood, G. J.; Hagen, D. E.; Sierau, B.; Wang, J.

    2014-12-01

    Inventories of particulate matter (PM) emissions from civil aviation and air quality models need to be validated using up-to-date measurement data corrected for sampling artifacts. We compared the measured black carbon (BC) mass and the total PM mass determined from particle size distributions (PSD) and effective density for a commercial turbofan engine CFM56-7B26/3. The effective density was then used to calculate the PM mass losses in the sampling system. The effective density was determined using a differential mobility analyzer and a centrifugal particle mass analyzer, and increased from engine idle to take-off by up to 60%. The determined mass-mobility exponents ranged from 2.37 to 2.64. The mean effective density determined by weighting the effective density distributions by PM volume was within 10% of the unit density (1000 kg/m3) that is widely assumed in aircraft PM studies. We found ratios close to unity between the PM mass determined by the integrated PSD method and the real-time BC mass measurements. The integrated PSD method achieved higher precision at ultra-low PM concentrations at which current mass instruments reach their detection limit. The line loss model predicted ∼60% PM mass loss at engine idle, decreasing to ∼27% at high thrust. Replacing the effective density distributions with unit density lead to comparable estimates that were within 20% and 5% at engine idle and high thrust, respectively. These results could be used for the development of a robust method for sampling loss correction of the future PM emissions database from commercial aircraft engines.

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

    PubMed

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

    2009-09-01

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

  9. Effect of Alum Additions to Poultry Litter on In-House Ammonia and Greenhouse Gas Concentrations and Emissions.

    PubMed

    Eugene, Branly; Moore, Philip A; Li, Hong; Miles, Dana; Trabue, Steven; Burns, Robert; Buser, Michael

    2015-09-01

    Alum [Al(SO4) ·14HO] addition to poultry litter has been shown to reduce ammonia (NH) concentrations in poultry houses; however, its effects on greenhouse gas (GHG; NO, CH, and CO) emissions is unknown. The objectives of this study were to determine the effects of alum additions on (i) in-house NH and GHG concentrations, (ii) NH and GHG emissions, and (iii) litter chemical properties. Two identical broiler houses located in northwest Arkansas were used for this study: one house was a control and the other was treated with alum between each flock of birds. Ventilation rates were coupled with in-house NH and GHG measurements to determine emission rates. Overall, alum additions significantly reduced the daily average in-house NH concentration by 42% (8.9 vs. 15.4 μL L), and the overall NH emission rate was reduced by 47% (7.2 vs. 13.4 kg d house). The average cumulative NH emission for the three flocks was 330 kg house flock for the alum-treated house and 617 kg house flock for the control. Concentrations and emissions of nitrous oxide (NO) and methane (CH) from the alum-treated house were not significantly different than the untreated house. However, carbon dioxide (CO) emissions were significantly higher from the untreated house than the alum-treated house. Alum also significantly increased litter N content and reduced the C/N ratio. These results indicate that the addition of alum to poultry litter is not only an effective management practice for reducing in-house NH concentrations and emissions but also significantly reduces CO emissions from poultry facilities.

  10. Biochar's effect on soil nitrous oxide emissions from a maize field with lime-adjusted pH treatment

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    Biochar, a carbon-rich, porous pyrolysis product of organic residues may positively affect plant yield and can, owing to its inherent stability, promote soil carbon sequestration when amended to agricultural soils. Another possible effect of biochar is the reduction in emissions of nitrous oxide (N2O). A number of laboratory incubations have shown significantly reduced N2O emissions from soil when mixed with biochar. Emission measurements under field conditions however are more scarce and show weaker or no reductions, or even increases in N2O emissions. One of the hypothesized mechanisms for reduced N2O emissions from soil is owing to the increase in soil pH following the application of alkaline biochar. To test the effect of biochar on N2O emissions in a temperate maize system, we set up a field trial with a 20 t ha-1 biochar treatment, a limestone treatment adjusted to the same pH as the biochar treatment, and a control treatment without any addition. An automated static chamber system measured N2O emissions for each replicate plot (n = 3) every 3.6 h over the course of 8 months. The field was conventionally fertilised at a rate of 160 kg-N ha-1 in 3 applications of 40, 80 and 40 kg-N ha-1. Cumulative N2O emissions were 53 % smaller in the biochar compared to the control treatment. However, the effect of the treatments overall was not statistically significant (p = 0.26) because of the large variability in the dataset. Limed soils emitted similar mean cumulative amounts of N2O as the control. This indicates that the observed N2O reduction effect of biochar was not caused by a pH effect.

  11. Site-specific diel mercury emission fluxes in landfill: Combined effects of vegetation and meteorological factors.

    PubMed

    Liu, Yang; Wu, Boran; Hao, Yongxia; Zhu, Wei; Li, Zhonggen; Chai, Xiaoli

    2017-01-01

    Mercury emission fluxes (MEFs) under different surface coverage conditions in a landfill were investigated in this study. The results show similar diel patterns of Hg emission flux under different coverage conditions, with peak fluxes occurring at midday and decreasing during night. We examined the effects of environmental factors on MEFs, such as the physiological characteristics of vegetation and meteorological conditions. The results suggest that growth of vegetation in the daytime facilitates the release of Hg in the anaerobic unit, while in the semi-aerobic unit, where vegetation had been removed, the higher mercury content of the cover soil prompted the photo-reduction pathway to become the main path of mercury release and increased MEFs. MEFs are positively correlated with solar radiation and air temperature, but negatively correlated with relative humidity. The correlation coefficients for MEFs with different environmental parameters indicate that in the anaerobic unit, solar radiation was the main influence on MEFs in September, while air temperature became the main determining factor in December. These observations suggest that the effects of meteorological conditions on the mercury release mechanism varies depending on the vegetation and soil pathways.

  12. Effects of Flamelet Generated Manifolds on Turbulent Flame Structure and Pollutant Emissions

    NASA Astrophysics Data System (ADS)

    Nunno, A. Cody; Grenga, Temistocle; Mueller, Michael E.

    2016-11-01

    Heat losses substantially modify turbulent combustion processes, especially the formation of pollutant emissions such as nitrogen oxides, which are highly sensitive to temperature. To account for heat loss effects in Large Eddy Simulation (LES) with flamelet models, a priori flamelet solutions are computed at reduced enthalpy. In this work, two methods for generating flamelets of lower enthalpy are compared to determine under what conditions the different methods produce different flame structure and different pollutant emissions in order to determine their validity limits. In the first method, a variable heat loss is introduced into the flamelet solutions that mimics a real heat loss, reducing the enthalpy primarily in the post-flame region of the flamelet. In the second method, fuel and oxidizer are converted to products in the unburned gases while retaining a constant unburned temperature, reducing the enthalpy over the entire flamelet. The two methods are compared in methane-air piloted turbulent premixed planar jet flames with increasing levels of dilution with both water and carbon dioxide that maintain a constant adiabatic flame temperature. The "product conversion" method is expected to mirror some of the same effects as physical dilution.

  13. Declining Dioxin concentrations in the Rhone River, France, attest to the effectiveness of emissions controls

    USGS Publications Warehouse

    Van Metre, Peter C.; Babut, Marc; Mourier, Brice; Mahler, Barbara J.; Roux, Gwenaelle; Desmet, Marc

    2015-01-01

    Emission-control policies have been implemented in Europe and North America since the 1990s for polychlorodibenzodioxins (PCDDs) and furans (PCDFs). To assess the effect of these policies on temporal trends and spatial patterns for these compounds in a large European river system, sediment cores were collected in seven depositional areas along the Rhone River in France, dated, and analyzed for PCDDs and PCDFs. Results show concentrations increase in the downstream direction and have decreased temporally at all sites during the last two decades, with an average decrease of 83% from 1992 to 2010. The time for a 50% decrease in concentrations (t1/2) averaged 6.9 ± 2.6 and 9.1 ± 2.9 years for the sum of measured PCDDs and PCDFs, respectively. Congener patterns are similar among cores and indicate dominance of regional atmospheric deposition and possibly weathered local sources. Local sources are clearly indicated at the most downstream site, where concentrations of the most toxic dioxin, TCDD, are about 2 orders of magnitude higher than at the other six sites. The relatively steep downward trends attest to the effects of the dioxin emissions reduction policy in Europe and suggest that risks posed to aquatic life in the Rhone River basin from dioxins and furans have been greatly reduced.

  14. Effects of soil moisture on the diurnal pattern of pesticide emission: Numerical simulation and sensitivity analysis

    NASA Astrophysics Data System (ADS)

    Reichman, Rivka; Yates, Scott R.; Skaggs, Todd H.; Rolston, Dennis E.

    2013-02-01

    Accurate prediction of pesticide volatilization is important for the protection of human and environmental health. Due to the complexity of the volatilization process, sophisticated predictive models are needed, especially for dry soil conditions. A mathematical model was developed to allow simulation of the diurnal variation of pesticide volatilization as affected by soil-water content, the air-solid interface partition coefficient, soil-water retention function and soil surface resistance processes. The model formulation considered two possible water retention functions and two soil surface resistance functions. To test the model, simulations were performed for ten successive days of drying under typical semi-arid summer conditions following application of the pesticide diazinon to either a loam or sand soil. Results showed that the temporal variation and magnitude of diazinon emission were strongly affected by the air-solid interface partition coefficient, soil-water content and the surface resistance function. The model was capable of simulating complex diurnal patterns in the peak emission rates which are caused by changes in soil water content and air-solid partitioning. The water retention function formulation had only a minor effect on the simulated water content and volatilization rates, whereas the soil surface resistance function significantly influenced the volatilization rate. Neither the water retention function nor the soil surface resistance formulation had a significant effect on the simulated soil temperature.

  15. A Simple Geometrical Model for Calculation of the Effective Emissivity in Blackbody Cylindrical Cavities

    NASA Astrophysics Data System (ADS)

    De Lucas, Javier

    2015-03-01

    A simple geometrical model for calculating the effective emissivity in blackbody cylindrical cavities has been developed. The back ray tracing technique and the Monte Carlo method have been employed, making use of a suitable set of coordinates and auxiliary planes. In these planes, the trajectories of individual photons in the successive reflections between the cavity points are followed in detail. The theoretical model is implemented by using simple numerical tools, programmed in Microsoft Visual Basic for Application and Excel. The algorithm is applied to isothermal and non-isothermal diffuse cylindrical cavities with a lid; however, the basic geometrical structure can be generalized to a cylindro-conical shape and specular reflection. Additionally, the numerical algorithm and the program source code can be used, with minor changes, for determining the distribution of the cavity points, where photon absorption takes place. This distribution could be applied to the study of the influence of thermal gradients on the effective emissivity profiles, for example. Validation is performed by analyzing the convergence of the Monte Carlo method as a function of the number of trials and by comparison with published results of different authors.

  16. Effects of nanoscale vacuum gap on photon-enhanced thermionic emission devices

    SciTech Connect

    Wang, Yuan; Liao, Tianjun; Zhang, Yanchao; Chen, Xiaohang E-mail: jcchen@xmu.edu.cn; Su, Shanhe; Chen, Jincan E-mail: jcchen@xmu.edu.cn

    2016-01-28

    A new model of the photon-enhanced thermionic emission (PETE) device with a nanoscale vacuum gap is established by introducing the quantum tunneling effect and the image force correction. Analytic expressions for both the thermionic emission and tunneling currents are derived. The electron concentration and the temperature of the cathode are determined by the particle conservation and energy balance equations. The effects of the operating voltage on the maximum potential barrier, cathode temperature, electron concentration and equilibrium electron concentration of the conduction band, and efficiency of the PETE device are discussed in detail for different given values of the vacuum gap length. The influence of the band gap of the cathode and flux concentration on the efficiency is further analyzed. The maximum efficiency of the PETE and the corresponding optimum values of the band gap and the operating voltage are determined. The results obtained here show that the efficiency of the PETE device can be significantly improved by employing a nanoscale vacuum gap.

  17. STRONG FIELD EFFECTS ON EMISSION LINE PROFILES: KERR BLACK HOLES AND WARPED ACCRETION DISKS

    SciTech Connect

    Wang Yan; Li Xiangdong

    2012-01-10

    If an accretion disk around a black hole is illuminated by hard X-rays from non-thermal coronae, fluorescent iron lines will be emitted from the inner region of the accretion disk. The emission line profiles will show a variety of strong field effects, which may be used as a probe of the spin parameter of the black hole and the structure of the accretion disk. In this paper, we generalize the previous relativistic line profile models by including both the black hole spinning effects and the non-axisymmetries of warped accretion disks. Our results show different features from the conventional calculations for either a flat disk around a Kerr black hole or a warped disk around a Schwarzschild black hole by presenting, at the same time, multiple peaks, rather long red tails, and time variations of line profiles with the precession of the disk. We show disk images as seen by a distant observer, which are distorted by the strong gravity. Although we are primarily concerned with the iron K-shell lines in this paper, the calculation is general and is valid for any emission lines produced from a warped accretion disk around a black hole.

  18. Modeling the effects of anode secondary electron emission on transmitted current in crossed-field diodes

    NASA Astrophysics Data System (ADS)

    Gopinath, Venkatesh; Vanderberg, Bo

    1996-11-01

    Recent experimental measurements of transmitted current in a crossed-field switch by Vanderberg and Eninger ( B. H. Vanderberg and J. E. Eninger, ``Space-charge limited current cut-off in crossed fields,'' presented at IEEE ICOPS'95, Madison, Wi. ) have shown that the measured values of transmitted current are significantly smaller than the theoretically predicted limit. The experiments also showed larger decrease in transmitted current for higher magnetic fields, implying an effect due to the higher angle of incidence of incident electrons (i.e., at values of B closer to B_H). Studies by Verboncoeur and Birdsall ( J. P. Verboncoeur and C. K. Birdsall. ``Rapid current transition in a crossed-field diode,'' Phys. Plasmas 3) 3, March 1996. have shown that even small amount ( < 1%) of over injection in a crossed-field diode near cut-off led to substantial decrease in transmitted current. In our current work, we show that the same effect can be triggered by the presence of secondary electron emission from the anode. This study models the dependence of emission upon incident electron angle and energy. Since the yield of secondary electrons increases with incident angle, this model follows the experimental results as B approaches B_Hull accurately. This work was supported in part by ONR under grant FD-N00014-90-J-1198

  19. Evaluating the effects of China's pollution controls on inter-annual trends and uncertainties of atmospheric mercury emissions

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Zhong, H.; Zhang, J.; Nielsen, C. P.

    2015-04-01

    China's anthropogenic emissions of atmospheric mercury (Hg) are effectively constrained by national air pollution control and energy efficiency policies. In this study, improved methods, based on available data from domestic field measurements, are developed to quantify the benefits of Hg abatement by various emission control measures. Those measures include increased use of (1) flue gas desulfurization (FGD) and selective catalyst reduction (SCR) systems in power generation; (2) precalciner kilns with fabric filters (FF) in cement production; (3) mechanized coking ovens with electrostatic precipitators (ESP) in iron and steel production; and (4) advanced production technologies in nonferrous metal smelting. Investigation reveals declining trends in emission factors for each of these sources, which together drive a much slower growth of total Hg emissions than the growth of China's energy consumption and economy, from 679 metric tons (t) in 2005 to 750 t in 2012. In particular, estimated emissions from the above-mentioned four source types declined 3% from 2005 to 2012, which can be attributed to expanded deployment of technologies with higher energy efficiencies and air pollutant removal rates. Emissions from other anthropogenic sources are estimated to increase by 22% during the period. The species shares of total Hg emissions have been stable in recent years, with mass fractions of around 55, 39, and 6% for gaseous elemental Hg (Hg0), reactive gaseous mercury (Hg2+), and particle-bound mercury (Hgp), respectively. The higher estimate of total Hg emissions than previous inventories is supported by limited simulation of atmospheric chemistry and transport. With improved implementation of emission controls and energy saving, a 23% reduction in annual Hg emissions from 2012 to 2030, to below 600 t, is expected at the most. While growth in Hg emissions has been gradually constrained, uncertainties quantified by Monte Carlo simulation for recent years have increased

  20. Ethanol Blends and Engine Operating Strategy Effects on Light-Duty Spark-Ignition Engine Particle Emissions

    SciTech Connect

    Szybist, James P; Youngquist, Adam D; Barone, Teresa L; Storey, John Morse; Moore, Wayne; Foster, Matthew; Confer, Keith

    2011-01-01

    Spark ignition (SI) engines with direct injection (DI) fueling can improve fuel economy and vehicle power beyond that of port fuel injection (PFI). Despite this distinct advantage, DI fueling often increases particle emissions such that SI exhaust may be subject to future particle emissions regulations. Challenges in controlling particle emissions arise as engines encounter varied fuel composition such as intermediate ethanol blends. Furthermore, modern engines are operated using unconventional breathing strategies with advanced cam-based variable valve actuation systems. In this study, we investigate particle emissions from a multi-cylinder DI engine operated with three different breathing strategies, fueling strategies and fuels. The breathing strategies are conventional throttled operation, early intake valve closing (EIVC) and late intake valve closing (LIVC); the fueling strategies are single injection DI (sDI), multi-injection DI (mDI), and PFI; and the fuels are emissions certification gasoline, E20 and E85. The results indicate the dominant factor influencing particle number concentration emissions for the sDI and mDI strategies is the fuel injection timing. Overly advanced injection timing results in particle formation due to fuel spray impingement on the piston, and overly retarded injection timing results in particle formation due to poor fuel and air mixing. In addition, fuel type has a significant effect on particle emissions for the DI fueling strategies. Gasoline and E20 fuels generate comparable levels of particle emissions, but E85 produces dramatically lower particle number concentration. The particle emissions for E85 are near the detection limit for the FSN instrument, and particle number emissions are one to two orders of magnitude lower for E85 relative to gasoline and E20. We found PFI fueling produces very low levels of particle emissions under all conditions and is much less sensitive to engine breathing strategy and fuel type than the DI

  1. Effects of surface contamination on the infrared emissivity and visible-light scattering of highly reflective surfaces at cryogenic temperatures

    NASA Technical Reports Server (NTRS)

    Viehmann, W.; Eubanks, A. G.

    1972-01-01

    A technique is described for the simultaneous in situ measurement of film thickness, refractive index, total normal emissivity, visible-light scattering, and reflectance of contaminant films on a highly reflective liquid-nitrogen cooled, stainless steel substrate. Emissivities and scattering data are obtained for films of water, carbon dioxide, silicone oil, and a number of aromatic and aliphatic hydrocarbons as a function of film thickness between zero and 20 microns. Of the contaminants investigated, water has by far the greatest effect on emissivity, followed by silicone oil, aliphatic hydrocarbons, aromatic hydrocarbons, and carbon dioxide. The emissivity increases more rapidly with film thickness between zero and 2.5 microns than at thicknesses greater than 2.5 microns. Scattering of visible light changes very little below 2 microns thickness but increases rapidly with thickness beyond 2 to 3 microns. The effect of contaminant films on passive radiation coolers is discussed.

  2. Effects of N-acetylcysteine on noise-induced temporary threshold shift and temporary emission shift

    NASA Astrophysics Data System (ADS)

    Robinette, Martin

    2001-05-01

    Animal research has shown that antioxidants can provide significant protection to the cochlea from traumatic noise exposure with some benefit when given after the exposure. Similar results in humans would have a significant impact on both prevention and treatment of noise-induced hearing loss. The current study evaluates the effectiveness of N-acetylcysteine (NAC) on temporary threshold shift (TTS) by using both behavioral and physiological measures. Sixteen healthy, normal-hearing subjects were given NAC or a placebo prior to exposure to a 10-min, 102-dB narrow-band noise, centered at 2 kHz. This exposure was designed to induce a 10-15-dB TTS. Following the noise exposure, pure-tone thresholds (Bekesy) and transient-evoked otoacoustic emissions (TEOAE) were measured for 60 min to monitor the effects of NAC on TTS recovery. Postexposure measures were compared to baseline data. [Work supported by American BioHealth Group.

  3. Effects of N-acetylcysteine on noise-induced temporary threshold shift and temporary emission shift

    NASA Astrophysics Data System (ADS)

    Robinette, Martin

    2004-05-01

    Animal research has shown that antioxidants can provide significant protection to the cochlea from traumatic noise exposure with some benefit when given after the exposure. Similar results in humans would have a significant impact on both prevention and treatment of noise-induced hearing loss. The current study evaluates the effectiveness of N-acetylcysteine (NAC) on temporary threshold shift (TTS) by using both behavioral and physiological measures. Sixteen healthy, normal-hearing subjects were given NAC or a placebo prior to exposure to a 10-min, 102-dB narrow-band noise, centered at 2 kHz. This exposure was designed to induce a 10-15-dB TTS. Following the noise exposure, pure-tone thresholds (Bekesy) and transient-evoked otoacoustic emissions (TEOAE) were measured for 60 min to monitor the effects of NAC on TTS recovery. Postexposure measures were compared to baseline data. [Work supported by American BioHealth Group.

  4. Space Environment Effects: Model for Emission of Solar Protons (ESP): Cumulative and Worst Case Event Fluences

    NASA Technical Reports Server (NTRS)

    Xapsos, M. A.; Barth, J. L.; Stassinopoulos, E. G.; Burke, E. A.; Gee, G. B.

    1999-01-01

    The effects that solar proton events have on microelectronics and solar arrays are important considerations for spacecraft in geostationary and polar orbits and for interplanetary missions. Designers of spacecraft and mission planners are required to assess the performance of microelectronic systems under a variety of conditions. A number of useful approaches exist for predicting information about solar proton event fluences and, to a lesser extent, peak fluxes. This includes the cumulative fluence over the course of a mission, the fluence of a worst-case event during a mission, the frequency distribution of event fluences, and the frequency distribution of large peak fluxes. Naval Research Laboratory (NRL) and NASA Goddard Space Flight Center, under the sponsorship of NASA's Space Environments and Effects (SEE) Program, have developed a new model for predicting cumulative solar proton fluences and worst-case solar proton events as functions of mission duration and user confidence level. This model is called the Emission of Solar Protons (ESP) model.

  5. Separating medial olivocochlear from acoustic reflex effects on transient evoked otoacoustic emissions in unanesthetized mice

    NASA Astrophysics Data System (ADS)

    Xu, Yingyue; Cheatham, Mary Ann; Siegel, Jonathan

    2015-12-01

    Descending neural pathways in the mammalian auditory system are believed to modulate the function of the peripheral auditory system [3, 8, 10]. These pathways include the medial olivocochlear (MOC) efferent innervation to the cochlear outer hair cells (OHCs) and the acoustic reflex pathways mediating middle ear muscle (MEM) contractions. The MOC effects can be monitored noninvasively using otoacoustic emissions (OAEs) [5, 6], which are acoustic byproducts of cochlear function [7]. In this study, we applied a sensitive method to determine when and to what degree contralateral MEM suppression contaminated MOC efferent effects on TEOAEs in unanesthetized mice. The lowest contralateral broadband noise evoking MEM contractions varied across animals. Examples of potential MOC-mediated TEOAE suppression with contralateral noise below MEM contraction thresholds were seen, but this behavior did not occur in the majority of cases.

  6. Effects of combustion and operating conditions on PCDD/PCDF emissions from power boilers burning salt-laden wood waste.

    PubMed

    Leclerc, Denys; Duo, Wen Li; Vessey, Michelle

    2006-04-01

    This paper discusses the effects of combustion conditions on PCDD/PCDF emissions from pulp and paper power boilers burning salt-laden wood waste. We found no correlation between PCDD/PCDF emissions and carbon monoxide emissions. A good correlation was, however, observed between PCDD/PCDF emissions and the concentration of stack polynuclear aromatic hydrocarbons (PAHs) in the absence of TDF addition. Thus, poor combustion conditions responsible for the formation of products of incomplete combustion (PICs), such as PAHs and PCDD/PCDF precursors, increase PCDD/PCDF emissions. PAH concentrations increased with higher boiler load and/or low oxygen concentrations at the boiler exit, probably because of lower available residence times and insufficient excess air. Our findings are consistent with the current understanding that high ash carbon content generally favours heterogeneous reactions leading to either de novo synthesis of PCDD/PCDFs or their direct formation from precursors. We also found that, in grate-fired boilers, a linear increase in the grate/lower furnace temperature produces an exponential decrease in PCDD/PCDF emissions. Although the extent of this effect appears to be mill-specific, particularly at low temperatures, the results indicate that increasing the combustion temperature may decrease PCDD/PCDF emissions. It must be noted, however, that there are other variables, such as elevated ESP and stack temperatures, a high hog salt content, the presence of large amounts of PICs and a high Cl/S ratio, which contribute to higher PCDD/PCDFs emissions. Therefore, higher combustion temperatures, by themselves, will not necessarily result in low PCDD/PCDFs emissions.

  7. Multiple effects and uncertainties of emission control policies in China: Implications for public health, soil acidification, and global temperature.

    PubMed

    Zhao, Yu; McElroy, Michael B; Xing, Jia; Duan, Lei; Nielsen, Chris P; Lei, Yu; Hao, Jiming

    2011-11-15

    Policies to control emissions of criteria pollutants in China may have conflicting impacts on public health, soil acidification, and climate. Two scenarios for 2020, a base case without anticipated control measures and a more realistic case including such controls, are evaluated to quantify the effects of the policies on emissions and resulting environmental outcomes. Large benefits to public health can be expected from the controls, attributed mainly to reduced emissions of primary PM and gaseous PM precursors, and thus lower ambient concentrations of PM2.5. Approximately 4% of all-cause mortality in the country can be avoided (95% confidence interval: 1-7%), particularly in eastern and north-central China, regions with large population densities and high levels of PM2.5. Surface ozone levels, however, are estimated to increase in parts of those regions, despite NOX reductions. This implies VOC-limited conditions. Even with significant reduction of SO2 and NOX emissions, the controls will not significantly mitigate risks of soil acidification, judged by the exceedance levels of critical load (CL). This is due to the decrease in primary PM emissions, with the consequent reduction in deposition of alkaline base cations. Compared to 2005, even larger CL exceedances are found for both scenarios in 2020, implying that PM control may negate any recovery from soil acidification due to SO2 reductions. Noting large uncertainties, current polices to control emissions of criteria pollutants in China will not reduce climate warming, since controlling SO2 emissions also reduces reflective secondary aerosols. Black carbon emission is an important source of uncertainty concerning the effects of Chinese control policies on global temperature change. Given these conflicts, greater consideration should be paid to reconciling varied environmental objectives, and emission control strategies should target not only criteria pollutants but also species such as VOCs and CO2.

  8. Effects of conservation tillage practices on ammonia emissions from Loess Plateau rain-fed winter wheat fields

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Zhou, Chunju; Li, Na; Han, Kun; Meng, Yuan; Tian, Xiaoxiao; Wang, Linquan

    2015-03-01

    Ammonia emissions from agricultural activities contribute to air pollution. For the rain-fed winter wheat system in the Loess Plateau there is a lack of information about ammonia emissions. Current study aimed to provide field data on ammonia emissions affected by conservation tillage practices and nitrogen applications. A two-year field experiment was conducted during 2011-2013 wheat growing seasons followed a split-plot design. Main plots consisted of one conventional tillage (CT, as the control) and five conservation tillage systems, i.e., stalk mulching (SM), film mulching (FM), ridge tillage (RT), ridge tillage with film mulch on the ridge (RTfm), and ridge tillage with film mulch on the ridge and stalk mulch in the furrow (RTfmsm); while subplots consisted of two nitrogen application rates, i.e., 0 and 180 kg N ha-1. Ammonia emissions were measured using an acid trapping method with vented chambers. Results showed ammonia fluxes peaked during the first 10 days after fertilization. On average, nitrogen application increased ammonia emissions by 26.5% (1.31 kg N ha-1) compared with treatments without nitrogen application (P < 0.05). Ammonia fluxes were strongly dependent on soil ammonium, moisture, and temperature. Tillage systems had significant effects on ammonia emissions. On average, conservation tillage practices reduced ammonia emissions by 7.7% (0.46 kg N ha-1) compared with conventional tillage (P < 0.05), with FM most effective. Deep-band application of nitrogen fertilizer, stalk mulches, and film mulches were responsible for reductions in ammonia emissions from nitrogen fertilization in conservation tillage systems, thus they were recommended to reduce ammonia emissions from winter wheat production regions in the southern Loess Plateau.

  9. Effects of Frame-Dragging on X-ray Emission from Black Holes and Neutron Stars

    NASA Astrophysics Data System (ADS)

    Markovic, D.; Lamb, F. K.

    2000-10-01

    In previous work on the effects of frame-dragging on viscous accretion disks around black holes and neutron stars, we discovered gravitomagnetically precessing global modes localized near the inner edge of the Keplerian flow. The highest-frequency modes of this type precess in the prograde direction with frequencies slightly lower than the Lense-Thirring precession frequency at the mean radius of the mode. Contrary to what had been expected since the pioneering work of Bardeen & Petterson, these modes are very weakly damped (Q ≈ 20--50) and are therefore likely to be excited. We present analytical arguments that shed further light on the nature of these modes and allow a better understanding of the symmetry-breaking pattern of viscous dissipation they create. The two highest-frequency modes tilt the innermost part of the Keplerian flow, redirecting gas crossing the sonic radius. As we discuss, these modes are likely to be the most easily excited and may be excited by magnetoturbulence in the disk or interaction of the disk with a stellar magnetic field. They may modulate X-ray emission from black holes and neutron stars by periodically altering the inspiral of gas from the Keplerian disk, by periodically obscuring emission from the inner disk or star, or by creating a rotating pattern of enhanced emission. This modulation is expected to create power spectral peaks at ~1--10 Hz in black hole sources and at ~10--40 Hz in the kilohertz QPO sources. It may also produce sidebands on the kilohertz QPOs, separated from the main peaks by ~10--40 Hz. Detecting and measuring the frequencies of these modes would provide valuable new information about the strongly curved, twisting spacetime expected near spinning neutron stars and black holes. This research was supported in part by the NSF and NASA.

  10. Effect of emissivity uncertainty on surface temperature retrieval over urban areas: Investigations based on spectral libraries

    NASA Astrophysics Data System (ADS)

    Chen, Feng; Yang, Song; Su, Z.; Wang, Kai

    2016-04-01

    Land surface emissivity (LSE) is a prerequisite for retrieving land surface temperature (LST) through single channel methods. According to error model, a 0.01 (1%) uncertainty of LSE may result in a 0.5 K error in LST under a moderate condition, while an obvious error (approximately 1 K) is possible under a warmer and less humid situation. Significant emissivity variations are presented among the anthropogenic materials in three spectral libraries, which raise a critical question that whether urban LSE can be estimated accurately to meet the needs for LST retrieval. Methods widely used for urban LSE estimation are investigated, including the classification-based method, the spectral-index based method, and the linear spectral mixture model (LSMM). Results indicate that the classification-based method may not be effectively applicable for urban LSE estimation, due mainly to the insignificant relation between the short-wave multispectral reflectance and the long-wave thermal emissivity shown by the spectra. Compared with the classification-based method, the LSMM shows relatively more accurate predictions, whereas, the performance of the LSMM largely depends on the determination of endmembers. Obvious uncertainties in LSE estimation likely appear if endmembers are determined improperly. Increasing the spectra for endmembers is a practical and beneficial means for LSMM when there is not a priori knowledge, which emphasizes the necessity of building a comprehensive spectral library of urban materials. Furthermore, the LST retrieval from a single channel of Landsat 8 is more challenging as compared with the retrieval from the channels of its predecessors-Landsat 4/5/7.

  11. Soil CO2 emissions from Northern Andean páramo ecosystems: effects of fallow agriculture.

    PubMed

    Cabaneiro, Ana; Fernandez, Irene; Pérez-Ventura, Luis; Carballas, Tarsy

    2008-03-01

    The effects of fallow agriculture on soil organic matter (SOM) dynamics and CO2 emissions were assessed in the tropical Andean páramo ecosystem. Possible changes during the cultivation-fallow cycle were monitored in four areas of the Quebrada Piñuelas valley (Venezuela). Uncultivated soils and plots at different stages of a complete cultivation--fallow cycle were incubated, and SOM mineralization kinetics was determined. Soils exhibited a low SOM mineralization activity, total CO2 evolved never reaching 3% of soil carbon, pointing to a stabilized SOM. Potential soil CO2 effluxes differed significantly according to their plot aspect: northeast (NE)-aspect soils presented higher CO2 effluxes than southwest (SW)-aspect soils. Soil CO2 emissions decreased after ploughing as compared to virgin páramo; low CO2 effluxes were still observed during cropping periods, increasing progressively to reach the highest values after 4-5 y of fallow. In all cases, experimental C mineralization data was fitted to a double exponential kinetic model. High soil labile C pool variability was observed, and two different trends were identified: NE-oriented soils showed more labile C and a wider range of values than SW-facing soils. Labile C positively correlated with CO2 effluxes and negatively with its instantaneous mineralization rate. The instantaneous mineralization rate of the recalcitrant C pool positively correlated with %C evolved as CO2 and negatively with soil C and Al2O3 contents, suggesting the importance of aluminum on SOM stability. The CO2 effluxes from these ecosystems, as well as the proportion of soil C released to the atmosphere, seem to depend not only on the size of the labile C pool but also on the accessibility of the more stabilized SOM. Therefore, fallow agriculture produces moderate changes in SOM quality and temporarily alters the CO2 emission capacity of these soils.

  12. Effect of plasmonic losses on light emission enhancement in quantum-wells coupled to metallic gratings

    NASA Astrophysics Data System (ADS)

    Sadi, Toufik; Oksanen, Jani; Tulkki, Jukka

    2013-12-01

    Recent experimental work has shown significant luminescence enhancement from near-surface quantum-well (QW) structures using metallic grating to convert surface plasmon (SP) modes into radiative modes. This work introduces a detailed theoretical study of plasmonic losses and the role of SPs in improving light extraction from grated light-emitting QW structures, using the fluctuational electrodynamics method. The method explains experimental results demonstrating emission enhancement, light scattering, and plasmonic coupling in the structures. We study these effects in angle-resolved reflectometry and luminescence setups in InGaN QW structures with silver grating. In contrast to experiments, our model allows direct calculation of the optical losses. The model predicts that the plasmonic coupling and scattering increases light emission by a factor of up to three compared to a flat semiconductor structure. This corresponds to reducing the absorption losses from approximately 93% in the ungrated metallic structure to 75% in the grated structure. Lower losses are associated with a significant emission enhancement enabled by the SPs of silver/GaN interfaces, which are present in the blue/green wavelength range, and can be optimized by carefully nanostructuring the metal layer and by the positioning of the QW. In general, the enhancement results from the interplay of mode scattering, conversion of SP energy directly into light, and losses in the metallic grating. The reported losses are very high when compared to the losses present in modern light-emitting diodes (LEDs). Albeit, our work provides tools needed for further optimization of plasmonic light extraction, eventually leading to highly efficient LEDs.

  13. Effects of Surface Treatments on Secondary Electron Emission from CVD Diamond Films

    NASA Technical Reports Server (NTRS)

    Mearini, G. T.; Krainsky, I. L.; Dayton, J. A., Jr.; Zorman, Christian; Wang, Yaxin; Lamouri, A.

    1995-01-01

    Secondary electron emission (SEE) properties of polycrystalline diamond films grown by chemical vapor deposition (CVD) were measured. The total secondary yield (sigma) from as-grown samples was observed to be as high as 20 at room temperature and 48 while heating at 700 K in vacuum. Electron-beam-activated, alkali-terminated diamond films have shown stable values of sigma as high as 60 when coated with CsI and similarly high values when coated with other alkali halides. Diamond coated with BaF2 had a stable sigma of 6, but no enhancement of the SEE properties was observed with coatings of Ti or Au. Hydrogen was identified to give rise to this effect in as-grown films. However, electron beam exposure led to a reduction in sigma values as low as 2. Exposure to a molecular hydrogen environment restored sigma to its original value after degradation, and enabled stable secondary emission during electron beam exposure. Atomic hydrogen and hydrogen plasma treatments were performed on diamond/Mo samples in an attempt to increase the near-surface hydrogen concentration which might lead to increased stability in the secondary emission. Raman scattering analysis, scanning electron microscopy, and Auger electron spectroscopy (AES) confirmed that hydrogen plasma and atomic hydrogen treatments improved the quality of the CVD diamond significantly. Elastic recoil detection (ERD) showed that heating as-grown diamond targets to 7OO K, which was correlated with an increase in sigma, removed contaminants from the surface but did not drive hydrogen from the diamond bulk. ERD showed that the hydrogen plasma treatment produced an increase in the hydrogen concentration in the near-surface region which did not decrease while heating in vacuum at 700 K, but no improvement in the SEE properties was observed.

  14. The effect of dust emissions from open storage piles to particle ambient concentration and human exposure.

    PubMed

    Chalvatzaki, E; Aleksandropoulou, V; Glytsos, T; Lazaridis, M

    2012-12-01

    The current study focus on the determination of dust emissions from piles in open storage yards of a municipal solid waste (MSW) composting site and the subsequent atmospheric dust dispersion. The ISC3-ST (Industrial Source Complex Version 3 - Short Term) model was used for the evaluation of the PM(10) ambient concentrations associated with the dispersion of MSW compost dust emissions in air. Dust emission rates were calculated using the United States Environmental Protection Agency proposed dust resuspension formulation from open storage piles using local meteorological data. The dispersion modelling results on the spatial distribution of PM(10) source depletion showed that the maximum concentrations were observed at a distance 25-75 m downwind of the piles in the prevailing wind direction. Sensitivity calculations were performed also to reveal the effect of the compost pile height, the friction velocity and the receptor height on the ambient PM(10) concentration. It was observed that PM(10) concentrations (downwind in the prevailing wind direction) increased with increasing the friction velocity, increasing the pile height (for distances greater than 125 m from the source) and decreasing the receptor height (for distances greater than 125 m from the source). Furthermore, the results of ISC3-ST were analysed with the ExDoM (Exposure Dose Model) human exposure model. The ExDoM is a model for calculating the human exposure and the deposition dose, clearance, and finally retention of aerosol particles in the human respiratory tract (RT). PM(10) concentration at the composting site was calculated as the sum of the concentration from compost pile dust resuspension and the background concentration. It was found that the exposure to PM(10) and deposited lung dose for an adult Caucasian male who is not working at the composting site is less by 20-74% and 29-84%, respectively, compared to those for a worker exposed to PM concentrations at the composting site.

  15. Effect of plasmonic losses on light emission enhancement in quantum-wells coupled to metallic gratings

    SciTech Connect

    Sadi, Toufik; Oksanen, Jani; Tulkki, Jukka

    2013-12-14

    Recent experimental work has shown significant luminescence enhancement from near-surface quantum-well (QW) structures using metallic grating to convert surface plasmon (SP) modes into radiative modes. This work introduces a detailed theoretical study of plasmonic losses and the role of SPs in improving light extraction from grated light-emitting QW structures, using the fluctuational electrodynamics method. The method explains experimental results demonstrating emission enhancement, light scattering, and plasmonic coupling in the structures. We study these effects in angle-resolved reflectometry and luminescence setups in InGaN QW structures with silver grating. In contrast to experiments, our model allows direct calculation of the optical losses. The model predicts that the plasmonic coupling and scattering increases light emission by a factor of up to three compared to a flat semiconductor structure. This corresponds to reducing the absorption losses from approximately 93% in the ungrated metallic structure to 75% in the grated structure. Lower losses are associated with a significant emission enhancement enabled by the SPs of silver/GaN interfaces, which are present in the blue/green wavelength range, and can be optimized by carefully nanostructuring the metal layer and by the positioning of the QW. In general, the enhancement results from the interplay of mode scattering, conversion of SP energy directly into light, and losses in the metallic grating. The reported losses are very high when compared to the losses present in modern light-emitting diodes (LEDs). Albeit, our work provides tools needed for further optimization of plasmonic light extraction, eventually leading to highly efficient LEDs.

  16. (AWMA) IMPROVING EMISSION INVENTORIES FOR EFFECTIVE AIR-QUALITY MANAGEMENT ACROSS NORTH AMERICA - A NARSTO ASSESSMENT

    EPA Science Inventory

    The NARSTO Ozone and Particulate Matter Assessments emphasized that emission inventories are critical to the success of air quality management programs and that emissions inventories in Canada, Mexico, and the United States need improvement to meet expectations for quality, timel...

  17. IMPROVING EMISSION INVENTORIES FOR EFFECTIVE AIR-QUALITY MANAGMENT ACROSS NORTH AMERICA - A NARSTO ASSESSMENT

    EPA Science Inventory

    The NARSTO Ozone and Particulate Matter Assessments emphasized that emission inventories are critical to the success of air quality management programs and that emissions inventories in Canada, Mexico, and the United States need improvement to meet expectations for quality, timel...