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.

Residual Effects of Fertilization History Increase Nitrous Oxide Emissions from Zero-N Controls: Implications for Estimating Fertilizer-Induced Emission Factors.

PubMed

LaHue, Gabriel T; van Kessel, Chris; Linquist, Bruce A; Adviento-Borbe, Maria Arlene; Fonte, Steven J

2016-09-01

Agricultural N fertilization is the dominant driver of increasing atmospheric nitrous oxide (NO) concentrations over the past half-century, yet there is considerable uncertainty in estimates of NO emissions from agriculture. Such estimates are typically based on the amount of N applied and a fertilizer-induced emission factor (EF), which is calculated as the difference in emissions between a fertilized plot and a zero-N control plot divided by the amount of N applied. A fertilizer-induced EF of 1% is currently recognized by the Intergovernmental Panel on Climate Change (IPCC) based on several studies analyzing published field measurements of NO emissions. Although many zero-N control plots used in these measurements received historical N applications, the potential for a residual impact of these inputs on NO emissions has been largely ignored and remains poorly understood. To address this issue, we compared NO emissions under laboratory conditions from soils sampled within zero-N control plots that had historically received N inputs versus soils from plots that had no N inputs for 20 yr. Historical N fertilization of zero-N control plots increased initial NO emissions by roughly one order of magnitude on average relative to historically unfertilized control plots. Higher NO emissions were positively correlated with extractable N and potentially mineralizable N. This finding suggests that accounting for fertilization history may help reduce the uncertainty associated with the IPCC fertilizer-induced EF and more accurately estimate the contribution of fertilizer N to agricultural NO emissions, although further research to demonstrate this relationship in the field is needed. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Noble metals: a toxicological appraisal of potential new environmental contaminants.

PubMed Central

Brubaker, P E; Moran, J P; Bridbord, K; Hueter, F G

1975-01-01

The public health benefits expected by reducing known hazardous emissions from mobile sources should not be compromised by increasing levels of other potentially hazardous unregulated emissions. Catalytic converters are going to be used to meet the statutory requirements on carbon monoxide and hydrocarbon emissions from light duty motor vehicles. Platinum and palladium metals are the catalytic materials to be used in these emission control devices. Preliminary experimental evidence and analysis of the impact of these control devices on the future use and demand for platinum indicates that this metal may appear at detectable levels in the environment by the end of this decade. At the present time, platinum and palladium are not present in the public environment and represent potentially new environmental contaminants as a consequence of use of this new abatement control technology. There is relatively little information available to adequately assess the potential health hazards that may be associated with exposure to these metals and their compounds. Analysis of the environmental problems and concerns associated with possible new environmental contaminants are discussed. Limited estimates are made on community exposure by use of a meteorological dispersion model. Biodegradation potential and attention is also given to the limited toxicological information available. PMID:50939

Report: EPA Did Not Identify Volkswagen Emissions Cheating; Enhanced Controls Now Provide Reasonable Assurance of Fraud Detection

EPA Pesticide Factsheets

Report #18-P-0181, May 15, 2018. After uncovering VW's emissions fraud, the EPA's light-duty vehicle compliance program added controls to effectively detect and prevent noncompliance—a precursor to potential fraud.

Application rate affects the degradation rate and hence emissions of chloropicrin in soil

USDA-ARS?s Scientific Manuscript database

Increasingly stringent regulations to control soil-air emissions of soil fumigants has led to much research effort aimed at reducing emission potential. Using laboratory soil columns, we aimed to investigate the relationship between chloropicrin (CP) application rate and its emissions from soil acro...

CONTROL TECHNOLOGY OVERVIEW REPORT: CFC (CHLOROFLUOROCARBON) EMISSIONS FROM RIGID FOAM MANUFACTURING

EPA Science Inventory

The report estimates total chlorofluorocarbon (CFC) emissions from the various rigid foam manufacturing processes and from the foam products themselves, and examines potential methods for reducing these emissions. Options studied include replacement of CFC-blown products with alt...

Paradigms and challenges for bioapplication of rare earth upconversion luminescent nanoparticles: small size and tunable emission/excitation spectra.

PubMed

Sun, Ling-Dong; Wang, Ye-Fu; Yan, Chun-Hua

2014-04-15

Rare earth (RE) materials, which are excited in the ultraviolet and emit in the visible light spectrum, are widely used as phosphors for lamps and displays. In the 1960's, researchers reported an abnormal emission phenomenon where photons emitted from a RE element carried more energy than those absorbed, owing to the sequential energy transfer between two RE ions--Yb(3+)-sensitized Er(3+) or Tm(3+)--in the solid state. After further study, researchers named this abnormal emission phenomenon upconversion (UC) emission. More recent approaches take advantage of solution-based synthesis, which allows creation of homogenous RE nanoparticles (NPs) with controlled size and structure that are capable of UC emission. Such nanoparticles are useful for many applications, especially in biology. For these applications, researchers seek small NPs with high upconversion emission intensity. These UCNPs have the potential to have multicolor and tunable emissions via various activators. A vast potential for future development remains by developing molecular antennas and energy transfer within RE ions. We expect UCNPs with optimized spectra behavior to meet the increasing demand of potential applications in bioimaging, biological detection, and light conversion. This Account focuses on efforts to control the size and modulate the spectra of UCNPs. We first review efforts in size control. One method is careful control of the synthesis conditions to manipulate particle nucleation and growth, but more recently researchers have learned that the doping conditions can affect the size of UCNPs. In addition, constructing homogeneous core/shell structures can control nanoparticle size by adjusting the shell thickness. After reviewing size control, we consider how diverse applications impose different requirements on excitation and/or emission photons and review recent developments on tuning of UC spectral profiles, especially the extension of excitation/emission wavelengths and the adjustment and purification of emission colors. We describe strategies that employ various dopants and others that build rationally designed nanostructures and nanocomposites to meet these goals. As the understanding of the energy transfer in the UC process has improved, core/shell structures have been proved useful for simultaneous tuning of excitation and emission wavelengths. Finally, we present a number of typical examples to highlight the upconverted emission in various applications, including imaging, detection, and sensing. We believe that with deeper understanding of emission phenomena and the ability to tune spectral profiles, UCNPs could play an important role in light conversion studies and applications.

Greenhouse gas emission and groundwater pollution potentials of soils amended with different swine biochars

USDA-ARS?s Scientific Manuscript database

The objective of this research was to study the greenhouse gas emission and groundwater pollution potentials of the soils amended with various biochars using different biomass feedstocks and thermal processing conditions. Triplicate sets of small pots were designed; control soil consisting of Histi...

Evaluation of emission control strategies for airfield operations at the Los Angeles and San Francisco International Airports. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gelinas, C.G.

1978-08-01

This report reviews potential air pollutant emission reductions which could be achieved by various strategies to control airfield operations at Los Angeles and San Francisco International Airports, and examines safety problems, cost impacts, potential fuel savings, time frame for strategy implementation, and potential regulatory and jurisdictional conflicts associated with each strategy. Airfield emission sources studied included aircraft operation in the idle, taxi, takeoff, and landing modes; ground service vehicles; fuel handling and storage; and aircraft engine maintenance. Nineteen potential strategies were identified, and seven strategies were selected for detailed analysis and examination after a preliminary evaluation. Two strategies, aircraft towingmore » and reducing the number of operating engines on the ground, appear to provide the most significant emission reduction. Both of these strategies offer potential reductions in the range of 20 to 40 percent of the carbon monoxide and nitrogen oxides which are currently emitted by ground operations. The aircraft towing strategy also offers a comparable improvement in suspended particulate matter emissions. When the overall feasibility of each strategy is evaluated, the strategy to reduce the number of operating engines appears to be the most viable since its implementation would result in fuel savings, no apparent safety problems, and it can be implemented immediately.« less

Marginal abatement cost curve for nitrogen oxides incorporating controls, renewable electricity, energy efficiency, and fuel switching.

PubMed

Loughlin, Daniel H; Macpherson, Alexander J; Kaufman, Katherine R; Keaveny, Brian N

2017-10-01

A marginal abatement cost curve (MACC) traces out the relationship between the quantity of pollution abated and the marginal cost of abating each additional unit. In the context of air quality management, MACCs are typically developed by sorting control technologies by their relative cost-effectiveness. Other potentially important abatement measures such as renewable electricity, energy efficiency, and fuel switching (RE/EE/FS) are often not incorporated into MACCs, as it is difficult to quantify their costs and abatement potential. In this paper, a U.S. energy system model is used to develop a MACC for nitrogen oxides (NO x ) that incorporates both traditional controls and these additional measures. The MACC is decomposed by sector, and the relative cost-effectiveness of RE/EE/FS and traditional controls are compared. RE/EE/FS are shown to have the potential to increase emission reductions beyond what is possible when applying traditional controls alone. Furthermore, a portion of RE/EE/FS appear to be cost-competitive with traditional controls. Renewable electricity, energy efficiency, and fuel switching can be cost-competitive with traditional air pollutant controls for abating air pollutant emissions. The application of renewable electricity, energy efficiency, and fuel switching is also shown to have the potential to increase emission reductions beyond what is possible when applying traditional controls alone.

Investigations of the Impact of Biodiesel Metal Contaminants on Emissions Control Devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brookshear, Daniel W; Lance, Michael J; Mccormick, Robert

Biodiesel is a renewable fuel with the potential to displace a portion of petroleum use. However, as with any alternative fuel, in order to be a viable choice it must be compatible with the emissions control devices. The finished biodiesel product can contain up to 5 ppm Na + K and 5 ppm Ca + Mg, and these metal impurities can lead to durability issues with the devices used to control emissions in diesel vehicles. Significant work has been performed to understand how the presence of these metals impacts each individual component of diesel emissions control systems, and this chaptermore » summarizes the findings of these research efforts.« less

Investigations of the Impact of Biodiesel Metal Contaminants on Emissions Control Devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brookshear, D. W.; Lance, M. J.; McCormick, Robert L.

Biodiesel is a renewable fuel with the potential to displace a portion of petroleum use. However, as with any alternative fuel, in order to be a viable choice it must be compatible with the emissions control devices. The finished biodiesel product can contain up to 5 ppm Na+K and 5 ppm Ca+Mg, and these metal impurities can lead to durability issues with the devices used to control emissions in diesel vehicles. Significant work has been performed to understand how the presence of these metals impacts each individual component of diesel emissions control systems, and this chapter summarizes the findings ofmore » these research efforts.« less

Mercury emission to the atmosphere from municipal solid waste landfills: A brief review

NASA Astrophysics Data System (ADS)

Tao, Zhengkai; Dai, Shijin; Chai, Xiaoli

2017-12-01

Municipal solid waste (MSW) landfill is regarded as an important emission source of atmospheric mercury (Hg), which is associated with potential health and environmental risks, as outlined by the Minamata Convention on Hg. This review presents the current state of knowledge with regards to landfill Hg sources, Hg levels in MSW and cover soils, Hg emission to the atmosphere, available Hg biogeochemical transformations, research methods for Hg emission, and important areas for future research. In addition, strategies for controlling landfill Hg emissions are considered, including reducing the Hg load in landfill and in situ controls. These approaches mainly focus on Hg source reduction, Hg recycling programs, public education, and in situ technology such as timely soil cover, vegetation, and end-of-pipe technology for controlling Hg emission from landfill gas.

Particulate matter emissions from biochar-amended soils as a potential tradeoff to the negative emission potential

NASA Astrophysics Data System (ADS)

Ravi, Sujith; Sharratt, Brenton S.; Li, Junran; Olshevski, Stuart; Meng, Zhongju; Zhang, Jianguo

2016-10-01

Novel carbon sequestration strategies such as large-scale land application of biochar may provide sustainable pathways to increase the terrestrial storage of carbon. Biochar has a long residence time in the soil and hence comprehensive studies are urgently needed to quantify the environmental impacts of large-scale biochar application. In particular, black carbon emissions from soils amended with biochar may counteract the negative emission potential due to the impacts on air quality, climate, and biogeochemical cycles. We investigated, using wind tunnel experiments, the particulate matter emission potential of a sand and two agriculturally important soils amended with different concentrations of biochar, in comparison to control soils. Our results indicate that biochar application considerably increases particulate emissions possibly by two mechanisms-the accelerated emission of fine biochar particles and the generation and emission of fine biochar particles resulting from abrasion of large biochar particles by sand grains. Our study highlights the importance of considering the background soil properties (e.g., texture) and geomorphological processes (e.g., aeolian transport) for biochar-based carbon sequestration programs.

Assessment of volatile organic compound and hazardous air pollutant emissions from oil and natural gas well pads using mobile remote and on-site direct measurements.

PubMed

Brantley, Halley L; Thoma, Eben D; Eisele, Adam P

2015-09-01

Emissions of volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) from oil and natural gas production were investigated using direct measurements of component-level emissions on pads in the Denver-Julesburg (DJ) Basin and remote measurements of production pad-level emissions in the Barnett, DJ, and Pinedale basins. Results from the 2011 DJ on-site study indicate that emissions from condensate storage tanks are highly variable and can be an important source of VOCs and HAPs, even when control measures are present. Comparison of the measured condensate tank emissions with potentially emitted concentrations modeled using E&P TANKS (American Petroleum Institute [API] Publication 4697) suggested that some of the tanks were likely effectively controlled (emissions less than 95% of potential), whereas others were not. Results also indicate that the use of a commercial high-volume sampler (HVS) without corresponding canister measurements may result in severe underestimates of emissions from condensate tanks. Instantaneous VOC and HAP emissions measured on-site on controlled systems in the DJ Basin were significantly higher than VOC and HAP emission results from the study conducted by Eastern Research Group (ERG) for the City of Fort Worth (2011) using the same method in the Barnett on pads with low or no condensate production. The measured VOC emissions were either lower or not significantly different from the results of studies of uncontrolled emissions from condensate tanks measured by routing all emissions through a single port monitored by a flow measurement device for 24 hr. VOC and HAP concentrations measured remotely using the U.S. Environmental Protection Agency (EPA) Other Test Method (OTM) 33A in the DJ Basin were not significantly different from the on-site measurements, although significant differences between basins were observed. VOC and HAP emissions from upstream production operations are important due to their potential impact on regional ozone levels and proximate populations. This study provides information on the sources and variability of VOC and HAP emissions from production pads as well as a comparison between different measurement techniques and laboratory analysis protocols. On-site and remote measurements of VOC and HAP emissions from oil and gas production pads indicate that measurable emissions can occur despite the presence of control measures, often as a result of leaking thief hatch seals on condensate tanks. Furthermore, results from the remote measurement method OTM 33A indicate that it can be used effectively as an inspection technique for identifying oil and gas well pads with large fugitive emissions.

Risk-based prioritization among air pollution control strategies in the Yangtze River Delta, China.

PubMed

Zhou, Ying; Fu, Joshua S; Zhuang, Guoshun; Levy, Jonathan I

2010-09-01

The Yangtze River Delta (YRD) in China is a densely populated region with recent dramatic increases in energy consumption and atmospheric emissions. We studied how different emission sectors influence population exposures and the corresponding health risks, to inform air pollution control strategy design. We applied the Community Multiscale Air Quality (CMAQ) Modeling System to model the marginal contribution to baseline concentrations from different sectors. We focused on nitrogen oxide (NOx) control while considering other pollutants that affect fine particulate matter [aerodynamic diameter < or = 2.5 mum (PM2.5)] and ozone concentrations. We developed concentration-response (C-R) functions for PM2.5 and ozone mortality for China to evaluate the anticipated health benefits. In the YRD, health benefits per ton of emission reductions varied significantly across pollutants, with reductions of primary PM2.5 from the industry sector and mobile sources showing the greatest benefits of 0.1 fewer deaths per year per ton of emission reduction. Combining estimates of health benefits per ton with potential emission reductions, the greatest mortality reduction of 12,000 fewer deaths per year [95% confidence interval (CI), 1,200-24,000] was associated with controlling primary PM2.5 emissions from the industry sector and reducing sulfur dioxide (SO2) from the power sector, respectively. Benefits were lower for reducing NOx emissions given lower consequent reductions in the formation of secondary PM2.5 (compared with SO2) and increases in ozone concentrations that would result in the YRD. Although uncertainties related to C-R functions are significant, the estimated health benefits of emission reductions in the YRD are substantial, especially for sectors and pollutants with both higher health benefits per unit emission reductions and large potential for emission reductions.

Multi-field electron emission pattern of 2D emitter: Illustrated with graphene

NASA Astrophysics Data System (ADS)

Luo, Ma; Li, Zhibing

2016-11-01

The mechanism of laser-assisted multi-field electron emission of two-dimensional emitters is investigated theoretically. The process is basically a cold field electron emission but having more controllable components: a uniform electric field controls the emission potential barrier, a magnetic field controls the quantum states of the emitter, while an optical field controls electron populations of specified quantum states. It provides a highly orientational vacuum electron line source whose divergence angle over the beam plane is inversely proportional to square root of the emitter height. Calculations are carried out for graphene with the armchair emission edge, as a concrete example. The rate equation incorporating the optical excitation, phonon scattering, and thermal relaxation is solved in the quasi-equilibrium approximation for electron population in the bands. The far-field emission patterns, that inherit the features of the Landau bands, are obtained. It is found that the optical field generates a characteristic structure at one wing of the emission pattern.

Discussion on a Potential DJ Basin Pneumatic Controller ...

EPA Pesticide Factsheets

ORD NRMRL and Region 8 collaborators are conducting emission measurements and method development studies on pneumatic controllers (PCs) in the Uintah Basin, Utah (and potentially in Colorado), in cooperation with Oil and Natural gas (ONG) operators. ONG operations use PCs for production process control and safety functions. PCs emit gas to the atmosphere as they operate and sometimes they malfunction and emit more than they are supposed to. Because of the very large number of PCs in use, these devices contribute significantly to greenhouse gas (GHG) and volatile organic compound (VOC) emissions. There is considerable uncertainty in levels of real-world PC emissions and measurement methods for PCs are somewhat underdeveloped. In collaboration with EPA R8, the State of Colorado, (and industry participants in Step 2), ORD NRMRL is evaluating a potential follow-on research effort to the Uinta Basin Pneumatic Controller (PC) Study. The Uinta PC Study is described in a recent APPCD Research Highlight (attached )with results summarized in “Assessment of Uinta Basin Oil and Natural Gas Well Pad Pneumatic Controller Emissions”, E. Thoma et al., Journal of Environmental Protection, 8, 394-415, (2017). doi: 10.4236/jep.2017.84029; at (http://www.scirp.org/Journal/PaperInformation.aspx?PaperID=75669). This RAP research was funded by an EPA R8 RARE and ACE Task EM 1.2 (next gen. emissions measurements). For both technical and programmatic reasons, we seek to

Radiative forcing associated with particulate carbon emissions resulting from the use of mercury control technology.

PubMed

Lin, Guangxing; Penner, Joyce E; Clack, Herek L

2014-09-02

Injection of powdered activated carbon (PAC) adsorbents into the flue gas of coal fired power plants with electrostatic precipitators (ESPs) is the most mature technology to control mercury emissions for coal combustion. However, the PAC itself can penetrate ESPs to emit into the atmosphere. These emitted PACs have similar size and optical properties to submicron black carbon (BC) and thus could increase BC radiative forcing unintentionally. The present paper estimates, for the first time, the potential emission of PAC together with their climate forcing. The global average maximum potential emissions of PAC is 98.4 Gg/yr for the year 2030, arising from the assumed adoption of the maximum potential PAC injection technology, the minimum collection efficiency, and the maximum PAC injection rate. These emissions cause a global warming of 2.10 mW m(-2) at the top of atmosphere and a cooling of -2.96 mW m(-2) at the surface. This warming represents about 2% of the warming that is caused by BC from direct fossil fuel burning and 0.86% of the warming associated with CO2 emissions from coal burning in power plants. Its warming is 8 times more efficient than the emitted CO2 as measured by the 20-year-integrated radiative forcing per unit of carbon input (the 20-year Global Warming Potential).

Balancing effluent quality, economic cost and greenhouse gas emissions during the evaluation of (plant-wide) control/operational strategies in WWTPs.

PubMed

Flores-Alsina, Xavier; Arnell, Magnus; Amerlinck, Youri; Corominas, Lluís; Gernaey, Krist V; Guo, Lisha; Lindblom, Erik; Nopens, Ingmar; Porro, Jose; Shaw, Andy; Snip, Laura; Vanrolleghem, Peter A; Jeppsson, Ulf

2014-01-01

The objective of this paper was to show the potential additional insight that result from adding greenhouse gas (GHG) emissions to plant performance evaluation criteria, such as effluent quality (EQI) and operational cost (OCI) indices, when evaluating (plant-wide) control/operational strategies in wastewater treatment plants (WWTPs). The proposed GHG evaluation is based on a set of comprehensive dynamic models that estimate the most significant potential on-site and off-site sources of CO₂, CH₄ and N₂O. The study calculates and discusses the changes in EQI, OCI and the emission of GHGs as a consequence of varying the following four process variables: (i) the set point of aeration control in the activated sludge section; (ii) the removal efficiency of total suspended solids (TSS) in the primary clarifier; (iii) the temperature in the anaerobic digester; and (iv) the control of the flow of anaerobic digester supernatants coming from sludge treatment. Based upon the assumptions built into the model structures, simulation results highlight the potential undesirable effects of increased GHG production when carrying out local energy optimization of the aeration system in the activated sludge section and energy recovery from the AD. Although off-site CO₂ emissions may decrease, the effect is counterbalanced by increased N₂O emissions, especially since N₂O has a 300-fold stronger greenhouse effect than CO₂. The reported results emphasize the importance and usefulness of using multiple evaluation criteria to compare and evaluate (plant-wide) control strategies in a WWTP for more informed operational decision making. © 2013.

SOURCE CHARACTERIZATION AND CONTROL TECHNOLOGY ASSESSMENT OF METHYLENE CHLORIDE EMISSIONS FROM EASTMAN KODAK COMPANY, ROCHESTER, NY

EPA Science Inventory

The report gives results of an assessment of potential control technologies for methylene chloride (also known as dichloromethane or DCM) emission sources at Eastman Kodak Company's Kodak Park facility in Rochester, NY. DCM is a solvent used by Kodak in the manufacture of cellulo...

Costing climate change.

PubMed

Reay, David S

2002-12-15

Debate over how, when, and even whether man-made greenhouse-gas emissions should be controlled has grown in intensity even faster than the levels of greenhouse gas in our atmosphere. Many argue that the costs involved in reducing emissions outweigh the potential economic damage of human-induced climate change. Here, existing cost-benefit analyses of greenhouse-gas reduction policies are examined, with a view to establishing whether any such global reductions are currently worthwhile. Potential for, and cost of, cutting our own individual greenhouse-gas emissions is then assessed. I find that many abatement strategies are able to deliver significant emission reductions at little or no net cost. Additionally, I find that there is huge potential for individuals to simultaneously cut their own greenhouse-gas emissions and save money. I conclude that cuts in global greenhouse-gas emissions, such as those of the Kyoto Protocol, cannot be justifiably dismissed as posing too large an economic burden.

Exposure to diesel and gasoline engine emissions and the risk of lung cancer.

PubMed

Parent, Marie-Elise; Rousseau, Marie-Claude; Boffetta, Paolo; Cohen, Aaron; Siemiatycki, Jack

2007-01-01

Pollution from motor vehicles constitutes a major environmental health problem. The present paper describes associations between diesel and gasoline engine emissions and lung cancer, as evidenced in a 1979-1985 population-based case-control study in Montreal, Canada. Cases were 857 male lung cancer patients. Controls were 533 population controls and 1,349 patients with other cancer types. Subjects were interviewed to obtain a detailed lifetime job history and relevant data on potential confounders. Industrial hygienists translated each job description into indices of exposure to several agents, including engine emissions. There was no evidence of excess risks of lung cancer with exposure to gasoline exhaust. For diesel engine emissions, results differed by control group. When cancer controls were considered, there was no excess risk. When population controls were studied, the odds ratios, after adjustments for potential confounders, were 1.2 (95% confidence interval: 0.8, 1.8) for any exposure and 1.6 (95% confidence interval: 0.9, 2.8) for substantial exposure. Confidence intervals between risk estimates derived from the two control groups overlapped considerably. These results provide some limited support for the hypothesis of an excess lung cancer risk due to diesel exhaust but no support for an increase in risk due to gasoline exhaust.

Nutrient Controls on Methane Emissions in a Permafrost Thaw Subarctic Peatland

NASA Astrophysics Data System (ADS)

Kashi, N. N.; Perryman, C. R.; Malhotra, A.; Marek, E. A.; Giesler, R.; Varner, R. K.

2015-12-01

Permafrost peatlands in northern latitudes are large reservoirs of sequestered carbon that are vulnerable to climate change. While peatlands account for a small fraction of total global land surfaces, their potential to release sequestered carbon in response to higher temperatures is of concern. Of particular relevance is the conversion of these carbon stores into methane (CH4), a strong greenhouse gas with a global warming potential 20 times greater than that of CO2 over a 100-year time frame. Here, we explore how key nutrients impact the consumption of CH4 at the Stordalen Mire in Abisko, Sweden, a discontinuous permafrost peatland with expanding thaw over the last century. Peatland CH4 emissions are highly spatially variable due to multiple emission pathways and strong dependence on several environmental factors. Among controls on CH4 emissions, such as temperature and water table depth, primary production of wetland vegetation is also a strong factor in the variability of CH4 emissions. Plant community shifts among permafrost thaw stages subsequently change nutrient cycling and availability, which in turn impacts primary production. Early stages of permafrost thaw are mosaicked with a variety of vascular plants and mosses. We analyzed potential enzymatic activities of chitinase, glucosidase, and phosphatase as proxies for organic nitrogen, carbon, and phosphorus cycling, respectively, in tandem with potential CH4 oxidation rates. In addition, stoichiometric ratios of carbon, nitrogen, and phosphorus concentrations are used to illustrate nutrient limitation controls on CH4 oxidation rates. While CH4 emissions are low throughout initial thaw stages, < 7 CH4 mg m-2 day-1, we found they had the highest rates of potential CH4 oxidation. These permafrost thaw-induced CH4 oxidation rates are 5 and 11 times higher, in the surface and depth of the peat profile respectively, than subsequent aerobic permafrost thaw stages. As CH4 emissions are low in intact permafrost peatlands, these high rates of potential CH4 oxidation indicate the importance of plant communities and the methanotrophic microbes they harbor.

Life-cycle-assessment of the historical development of air pollution control and energy recovery in waste incineration.

PubMed

Damgaard, Anders; Riber, Christian; Fruergaard, Thilde; Hulgaard, Tore; Christensen, Thomas H

2010-07-01

Incineration of municipal solid waste is a debated waste management technology. In some countries it is the main waste management option whereas in other countries it has been disregarded. The main discussion point on waste incineration is the release of air emissions from the combustion of the waste, but also the energy recovery efficiency has a large importance. The historical development of air pollution control in waste incineration was studied through life-cycle-assessment modelling of eight different air pollution control technologies. The results showed a drastic reduction in the release of air emissions and consequently a significant reduction in the potential environmental impacts of waste incineration. Improvements of a factor 0.85-174 were obtained in the different impact potentials as technology developed from no emission control at all, to the best available emission control technologies of today (2010). The importance of efficient energy recovery was studied through seven different combinations of heat and electricity recovery, which were modelled to substitute energy produced from either coal or natural gas. The best air pollution control technology was used at the incinerator. It was found that when substituting coal based energy production total net savings were obtained in both the standard and toxic impact categories. However, if the substituted energy production was based on natural gas, only the most efficient recovery options yielded net savings with respect to the standard impacts. With regards to the toxic impact categories, emissions from the waste incineration process were always larger than those from the avoided energy production based on natural gas. The results shows that the potential environmental impacts from air emissions have decreased drastically during the last 35 years and that these impacts can be partly or fully offset by recovering energy which otherwise should have been produced from fossil fuels like coal or natural gas. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Greenhouse gas emission and groundwater pollution potentials of soils amended with raw and carbonized swine solids

USDA-ARS?s Scientific Manuscript database

The objective of this research is to study the greenhouse gas emission and groundwater pollution potentials of the soils amended with raw swine solids and swine biochars made from different thermochemical conditions. Triplicate sets of small pots were designed: 1) control soil with a 50/50 mixture o...

Control technology for integrated circuit fabrication at Micro-Circuit Engineering, Incorporated, West Palm Beach, Florida

NASA Astrophysics Data System (ADS)

Mihlan, G. I.; Mitchell, R. I.; Smith, R. K.

1984-07-01

A survey to assess control technology for integrated circuit fabrication was conducted. Engineering controls included local and general exhaust ventilation, shielding, and personal protective equipment. Devices or work stations that contained toxic materials that were potentially dangerous were controlled by local exhaust ventilation. Less hazardous areas were controlled by general exhaust ventilation. Process isolation was used in the plasma etching, low pressure chemical vapor deposition, and metallization operations. Shielding was used in ion implantation units to control X-ray emissions, in contact mask alignes to limit ultraviolet (UV) emissions, and in plasma etching units to control radiofrequency and UV emissions. Most operations were automated. Use of personal protective equipment varied by job function.

Mitigation of severe urban haze pollution by a precision air pollution control approach.

PubMed

Yu, Shaocai; Li, Pengfei; Wang, Liqiang; Wu, Yujie; Wang, Si; Liu, Kai; Zhu, Tong; Zhang, Yuanhang; Hu, Min; Zeng, Liming; Zhang, Xiaoye; Cao, Junji; Alapaty, Kiran; Wong, David C; Pleim, Jon; Mathur, Rohit; Rosenfeld, Daniel; Seinfeld, John H

2018-05-25

Severe and persistent haze pollution involving fine particulate matter (PM 2.5 ) concentrations reaching unprecedentedly high levels across many cities in China poses a serious threat to human health. Although mandatory temporary cessation of most urban and surrounding emission sources is an effective, but costly, short-term measure to abate air pollution, development of long-term crisis response measures remains a challenge, especially for curbing severe urban haze events on a regular basis. Here we introduce and evaluate a novel precision air pollution control approach (PAPCA) to mitigate severe urban haze events. The approach involves combining predictions of high PM 2.5 concentrations, with a hybrid trajectory-receptor model and a comprehensive 3-D atmospheric model, to pinpoint the origins of emissions leading to such events and to optimize emission controls. Results of the PAPCA application to five severe haze episodes in major urban areas in China suggest that this strategy has the potential to significantly mitigate severe urban haze by decreasing PM 2.5 peak concentrations by more than 60% from above 300 μg m -3 to below 100 μg m -3 , while requiring ~30% to 70% less emission controls as compared to complete emission reductions. The PAPCA strategy has the potential to tackle effectively severe urban haze pollution events with economic efficiency.

Role of photoexcited nitrogen dioxide chemistry on ozone formation and emission control strategy over the Pearl River Delta, China

EPA Science Inventory

A new hydroxyl radical formation pathway via photo-excited nitrogen dioxide chemistry is incorporated into a chemistry-only box model as well as a 3D air quality model to examine its potential role on ozone formation and emission control strategy over the Pearl River Delta region...

Diesel Emission Control -- Sulfur Effects (DECSE) Program; Phase I Interim Data Report No. 2: NO{sub x} Adsorber Catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

DOE; ORNL; NREL

1999-10-15

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 (NOx) 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 formore » multiple levels of fuel sulfur content. This interim report discusses the results of the DECSE test program that demonstrates the potential of NOx adsorber catalyst technology across the range of diesel engine operation with a fuel economy penalty less than 4%.« less

[Research advances in control of N2O emission from municipal solid waste landfill sites].

PubMed

Cai, Chuan-Yu; Li, Bo; Lü, Hao-Hao; Wu, Wei-Xiang

2012-05-01

Landfill is one of the main approaches for municipal solid waste treatment, and landfill site is a main emission source of greenhouse gases nitrous oxide (N2O) and methane (CH4). As a high-efficient trace greenhouse gas, N2O has a very high warming potential, with a warming capacity 296 times of CO2, and has a long-term stability in atmosphere, giving greater damage to the ozone layer. Aiming at the researches in the control of N2O emission from municipal solid waste landfill sites, this paper summarized the characteristics and related affecting factors of the N2O emission from the landfill sites, and put forward a series of the measures adaptable to the N2O emission control of present municipal solid waste landfill sites in China. Some further research focuses on the control of N2O emission from the landfill sites were also presented.

Reducing air pollutant emissions at airports by controlling aircraft ground operations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gelinas, C.G.; Fan, H.S.L.

1979-02-01

Potential reductions in air pollutant emissions were determined for four stategies to control aircraft ground operations at two case study airports, Los Angeles and San Francisco International Airports. Safety, cost, and fuel savings associated with strategy implementation were examined. Two strategies, aircraft towing and shutdown of one engine during taxi operations, provided significant emission reductions. However, there are a number of safety problems associated with aircraft towing. The shutdown of one engine while taxiing was found to be the most viable strategy because of substantial emission reductions, cost benefits resulting from fuel savings, and no apparent safety problems.

Neural-network-based navigation and control of unmanned aerial vehicles for detecting unintended emissions

NASA Astrophysics Data System (ADS)

Zargarzadeh, H.; Nodland, David; Thotla, V.; Jagannathan, S.; Agarwal, S.

2012-06-01

Unmanned Aerial Vehicles (UAVs) are versatile aircraft with many applications, including the potential for use to detect unintended electromagnetic emissions from electronic devices. A particular area of recent interest has been helicopter unmanned aerial vehicles. Because of the nature of these helicopters' dynamics, high-performance controller design for them presents a challenge. This paper introduces an optimal controller design via output feedback control for trajectory tracking of a helicopter UAV using a neural network (NN). The output-feedback control system utilizes the backstepping methodology, employing kinematic, virtual, and dynamic controllers and an observer. Optimal tracking is accomplished with a single NN utilized for cost function approximation. The controller positions the helicopter, which is equipped with an antenna, such that the antenna can detect unintended emissions. The overall closed-loop system stability with the proposed controller is demonstrated by using Lyapunov analysis. Finally, results are provided to demonstrate the effectiveness of the proposed control design for positioning the helicopter for unintended emissions detection.

Greenhouse gas emission and groundwater pollution potential of soils amended with raw swine manure, dry and wet pyrolyzed swine biochars

USDA-ARS?s Scientific Manuscript database

The objective of this research is to study the greenhouse gas emission and groundwater pollution potentials of the soils amended with raw swine solid and swine biochars made from different thermochemical conditions. Triplicate sets of small pots were designed: 1) control soil with a 50/50 mixture of...

Model predictive control of a lean-burn gasoline engine coupled with a passive selective catalytic reduction system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Pingen; Lin, Qinghua; Prikhodko, Vitaly Y.

Lean-burn gasoline engines have demonstrated 10–20% engine efficiency gain over stoichiometric engines and are widely considered as a promising technology for meeting the 54.5 miles-per-gallon (mpg) Corporate Average Fuel Economy standard by 2025. Nevertheless, NOx emissions control for lean-burn gasoline for meeting the stringent EPA Tier 3 emission standards has been one of the main challenges towards the commercialization of highly-efficient lean-burn gasoline engines in the United States. Passive selective catalytic reduction (SCR) systems, which consist of a three-way catalyst and SCR, have demonstrated great potentials of effectively reducing NOx emissions for lean gasoline engines but may cause significant fuelmore » penalty due to ammonia generation via rich engine combustion. The purpose of this study is to develop a model-predictive control (MPC) scheme for a lean-burn gasoline engine coupled with a passive SCR system to minimize the fuel penalty associated with passive SCR operation while satisfying stringent NOx and NH3 emissions requirements. Simulation results demonstrate that the MPC-based control can reduce the fuel penalty by 47.7% in a simulated US06 cycle and 32.0% in a simulated UDDS cycle, compared to the baseline control, while achieving over 96% deNOx efficiency and less than 15 ppm tailpipe ammonia slip. The proposed MPC control can potentially enable high engine efficiency gain for highly-efficient lean-burn gasoline engine while meeting the stringent EPA Tier 3 emission standards.« less

Potential of Diesel Engine, Emission Technology

DOT National Transportation Integrated Search

1980-03-01

This report surveys diesel engine emission technologies applicable to passenger cars and light trucks. The general design and operating features are presented and discussed. Current and state-of-the-art concepts are reviewed with the focus on control...

Impact of biodiesel on regulated and unregulated emissions, and redox and proinflammatory properties of PM emitted from heavy-duty vehicles.

PubMed

Karavalakis, Georgios; Gysel, Nicholas; Schmitz, Debra A; Cho, Arthur K; Sioutas, Constantinos; Schauer, James J; Cocker, David R; Durbin, Thomas D

2017-04-15

The emissions and the potential health effects of particulate matter (PM) were assessed from two heavy-duty trucks with and without emission control aftertreatment systems when operating on CARB ultra-low sulfur diesel (ULSD) and three different biodiesel blends. The CARB ULSD was blended with soy-based biodiesel, animal fat biodiesel, and waste cooking oil biodiesel at 50vol%. Testing was conducted over the EPA Urban Dynamometer Driving Schedule (UDDS) in triplicate for both trucks. The aftertreatment controls effectively decreased PM mass and number emissions, as well as the polycyclic aromatic hydrocarbons (PAHs) compared to the uncontrolled truck. Emissions of nitrogen oxides (NO x ) exhibited increases with the biodiesel blends, showing some feedstock dependency for the controlled truck. The oxidative potential of the emitted PM, measured by means of the dithiothreitol (DTT) assay, showed reductions with the use of biodiesel blends relative to CARB ULSD for the uncontrolled truck. Overall, the cellular responses to the particles from each fuel were reflective of the chemical content, i.e., particles from CARB ULSD were the most reactive and exhibited the highest cellular responses. Copyright © 2017 Elsevier B.V. All rights reserved.

Diminished mercury emission from waters with duckweed cover

NASA Astrophysics Data System (ADS)

Wollenberg, Jennifer L.; Peters, Stephen C.

2009-06-01

Duckweeds (Lemnaceae) are a widely distributed type of floating vegetation in freshwater systems. Under suitable conditions, duckweeds form a dense vegetative mat on the water surface, which reduces light penetration into the water column and limits gas exchange at the water-air interface by decreasing the area of open water surface. Experiments were conducted to determine whether duckweed decreases mercury emission by limiting gas diffusion across the water-air interface and attenuating light, or, conversely, enhances emission via transpiration of mercury vapor. Microcosm flux chamber experiments indicate that duckweed decreases mercury emission from the water surface compared to open water controls. Fluxes under duckweed were 17-67% lower than in controls, with lower fluxes occurring at higher percent cover. The decrease in mercury emission suggests that duckweed may limit emission through one of several mechanisms, including limited gas transport across the air-water interface, decreased photoreactions due to light attenuation, and plant-mercury interactions. The results of this experiment were applied to a model lake system to illustrate the magnitude of potential effects on mercury cycling. The mercury retained in the lake as a result of hindered emission may increase bioaccumulation potential in lakes with duckweed cover.

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.

The effect of diet manipulation on nitrous oxide and methane emissions from manure application to incubated grassland soils

NASA Astrophysics Data System (ADS)

Cardenas, L. M.; Chadwick, D.; Scholefield, D.; Fychan, R.; Marley, C. L.; Jones, R.; Bol, R.; Well, R.; Vallejo, A.

Changes to agricultural management, particularly of the nitrogen (N) input to farms, have great potential for mitigating emissions of N containing gases, especially the greenhouse gas nitrous oxide (N 2O). Manipulating diets fed to livestock is a potential method for controlling N excretion and emissions of greenhouse gases (GHG's) to the atmosphere. We selected three slurries derived from sheep that had been fed, either ensiled ryegrass ( Lolium hybridicum), lucerne ( Medicago sativa) or kale ( Brassica oleracea) and applied them to a grassland soil from the UK in a laboratory experiment using a special He/O 2 atmosphere incubation facility. The resulting fluxes of N 2O, CH 4 and N 2 were measured, with the largest total N fluxes generated by the ryegrass slurry treatment (14.23 ryegrass, 10.84 lucerne, 13.88 kale and 4.40 kg N ha -1 from the control). Methane was emitted only from the ryegrass slurry treatment. The isotopomer signatures for N 2O in the control and lucerne slurry treatments indicated that denitrification was the main process responsible for N 2O emissions.

Assessment of Emerging Regional Air Quality (AQ) and Greenhouse Gas (GHG) Impacts and Potential Mitigation Strategies in U.S. Energy Sectors

NASA Astrophysics Data System (ADS)

Kinnon, Michael Mac

The current domestic reliance on high-emitting fossil fuels for energy needs is the key driver of U.S. greenhouse gas (GHG) and pollutant emissions driving both climate change and regional air quality (AQ) concerns. Moving forward, emission sources in U.S. energy sectors will be subjected to changes driven by numerous phenomena, including technology evolution, environmental impacts, sustainability goals, and socioeconomic factors. This evolution will directly affect emissions source-related impacts on regional AQ that effective emissions control strategies must account for, including relative source contributions. Though previous studies have evaluated the emissions and AQ impacts of different sectors, technologies and fuels, most previous studies have assessed emissions impacts only without using advanced atmospheric models to accurately account for both spatial and temporal emissions perturbations and atmospheric chemistry and transport. In addition, few previous studies have considered the integration of multiple technologies and fuels in different U.S. regions.. Finally, most studies do not project emissions several decades into the future to assess what sources should be targeted with priority over time. These aspects are critical for understanding how both emissions sources and potential mitigation strategies impact the formation and fate of primary and secondary pollutants, including ground-level ozone and particulate matter concentrations. Therefore, this work utilizes a set of modeling tools to project and then to spatially and temporally resolve emissions as input into a 3-D Eulerian AQ model to assess how sources of emissions contribute to future atmospheric pollutant burdens. Further, analyses of the potential impacts of alternative energy strategies contained in potential mitigation strategies are conducted for priority targets to develop an understanding of how to maximize AQ benefits and avoid unforeseen deleterious tradeoffs between GHG reduction and AQ. Findings include changes in the relative contribution to AQ that elevate the importance of addressing emissions from all sectors and sources including some that may be more difficult to control, including industry, petroleum refineries, and nonlight duty vehicle transportation sources. Additionally, mitigation strategies must consider the full range of life cycle and system effects in order to avoid AQ tradeoffs spatially and temporally.

Multi-objective optimisation of wastewater treatment plant control to reduce greenhouse gas emissions.

PubMed

Sweetapple, Christine; Fu, Guangtao; Butler, David

2014-05-15

This study investigates the potential of control strategy optimisation for the reduction of operational greenhouse gas emissions from wastewater treatment in a cost-effective manner, and demonstrates that significant improvements can be realised. A multi-objective evolutionary algorithm, NSGA-II, is used to derive sets of Pareto optimal operational and control parameter values for an activated sludge wastewater treatment plant, with objectives including minimisation of greenhouse gas emissions, operational costs and effluent pollutant concentrations, subject to legislative compliance. Different problem formulations are explored, to identify the most effective approach to emissions reduction, and the sets of optimal solutions enable identification of trade-offs between conflicting objectives. It is found that multi-objective optimisation can facilitate a significant reduction in greenhouse gas emissions without the need for plant redesign or modification of the control strategy layout, but there are trade-offs to consider: most importantly, if operational costs are not to be increased, reduction of greenhouse gas emissions is likely to incur an increase in effluent ammonia and total nitrogen concentrations. Design of control strategies for a high effluent quality and low costs alone is likely to result in an inadvertent increase in greenhouse gas emissions, so it is of key importance that effects on emissions are considered in control strategy development and optimisation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Control Strategy Tool (CoST)

EPA Pesticide Factsheets

The EPA Control Strategy Tool (CoST) is a software tool for projecting potential future control scenarios, their effects on emissions and estimated costs. This tool uses the NEI and the Control Measures Dataset as key inputs. CoST outputs are projections of future control scenarios.

CONTROL OF DIOXIN, FURAN, AND MERCURY EMISSIONS FROM MUNICIPAL WASTE COMBUSTORS

EPA Science Inventory

There is a significant public and scientific concern over the potential risks of air pollution emissions from municipal waste combustors (MWCs). The primary pollutants of concern are polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/PCDFs), and mercury (Hg). Depending on...

Effectiveness evaluation of temporary emission control action in 2016 in winter in Shijiazhuang, China

NASA Astrophysics Data System (ADS)

Liu, Baoshuang; Cheng, Yuan; Zhou, Ming; Liang, Danni; Dai, Qili; Wang, Lu; Jin, Wei; Zhang, Lingzhi; Ren, Yibin; Zhou, Jingbo; Dai, Chunling; Xu, Jiao; Wang, Jiao; Feng, Yinchang; Zhang, Yufen

2018-05-01

To evaluate the environmental effectiveness of the control measures for atmospheric pollution in Shijiazhuang, China, a large-scale controlling experiment for emission sources of atmospheric pollutants (i.e. a temporary emission control action, TECA) was designed and implemented during 1 November 2016 to 9 January 2017. Compared to the no-control action and heating period (NCAHP), under unfavourable meteorological conditions, the mean concentrations of PM2.5, PM10, SO2, NO2, and chemical species (Si, Al, Ca2+, Mg2+) in PM2.5 during the control action and heating period (CAHP) still decreased by 8, 8, 5, 19, 30.3, 4.5, 47.0, and 45.2 %, respectively, indicating that the control measures for atmospheric pollution were effective. The effects of control measures in suburbs were better than those in urban area, especially for the control effects of particulate matter sources. The control effects for emission sources of carbon monoxide (CO) were not apparent during the TECA period, especially in suburbs, likely due to the increasing usage of domestic coal in suburbs along with the temperature decreasing.The results of positive matrix factorization (PMF) analysis showed that crustal dust, secondary sources, vehicle emissions, coal combustion and industrial emissions were main PM2.5 sources. Compared to the whole year (WY) and the no-control action and no-heating period (NCANHP), the contribution concentrations and proportions of coal combustion to PM2.5 increased significantly during other stages of the TECA period. The contribution concentrations and proportions of crustal dust and vehicle emissions to PM2.5 decreased noticeably during the CAHP compared to other stages of the TECA period. The contribution concentrations and proportions of industrial emissions to PM2.5 during the CAHP decreased noticeably compared to the NCAHP. The pollutants' emission sources during the CAHP were in effective control, especially for crustal dust and vehicles. However, the necessary coal heating for the cold winter and the unfavourable meteorological conditions had an offset effect on the control measures for emission sources to some degree. The results also illustrated that the discharge of pollutants might still be enormous even under such strict control measures.The backward trajectory and potential source contribution function (PSCF) analysis in the light of atmospheric pollutants suggested that the potential source areas mainly involved the surrounding regions of Shijiazhuang, i.e. south of Hebei and north of Henan and Shanxi. The regional nature of the atmospheric pollution in the North China Plain revealed that there is an urgent need for making cross-boundary control policies in addition to local control measures given the high background level of pollutants.The TECA is an important practical exercise but it cannot be advocated for as the normalized control measures for atmospheric pollution in China. The direct cause of atmospheric pollution in China is the emission of pollutants exceeding the air environment's self-purification capacity, which is caused by an unreasonable and unhealthy pattern for economic development in China.

Assessment of Pneumatic Controller Emission Measurements ...

EPA Pesticide Factsheets

Oil and Natural Gas (ONG) production facilities have the potential to emit greenhouse gases such as methane (CH4) and other hydrocarbons (HCs) to the atmosphere. ONG production sites have multiple emission sources including storage tank venting, enclosed combustion devices, engine exhaust, pneumatic controllers and uncontrolled leaks. Accounting for up to 37.8 percent of CH4 emissions, pneumatic controllers are one of the most significant sources of CH4 in ONG production field operations. Recent measurement studies used the only commercially-available high volume sampling (HVS) technology (Bacharach Hi Flow Sampler, Bacharach, Inc., New Kensington, PA) to quantify CH4 emission rates of pneumatic devices on ONG production pads and compare to inventory estimates. Other studies indicate that this HVS may malfunction, causing underestimates of emissions in certain scenarios encountered in ONG production and should not be used for some sources such as heavy emissions from condensate storage tanks. The HVS malfunction can occur on relatively large emissions, where the measured leak concentrations exceed 5%, and is ascribed to a sensor transition failure in the instrument. The HVS malfunction is believed to be exacerbated by several factors (large emission rates, amount of non-CH4 HCs in the emission stream, non-optimal HVS calibration frequency, firmware, and emission measurement coupling geometries). The degree to which HVS measurements of emissions from pneumatic co

Density-controlled, solution-based growth of ZnO nanorod arrays via layer-by-layer polymer thin films for enhanced field emission

NASA Astrophysics Data System (ADS)

Weintraub, Benjamin; Chang, Sehoon; Singamaneni, Srikanth; Han, Won Hee; Choi, Young Jin; Bae, Joonho; Kirkham, Melanie; Tsukruk, Vladimir V.; Deng, Yulin

2008-10-01

A simple, scalable, and cost-effective technique for controlling the growth density of ZnO nanorod arrays based on a layer-by-layer polyelectrolyte polymer film is demonstrated. The ZnO nanorods were synthesized using a low temperature (T = 90 °C), solution-based method. The density-control technique utilizes a polymer thin film pre-coated on the substrate to control the mass transport of the reactant to the substrate. The density-controlled arrays were investigated as potential field emission candidates. The field emission results revealed that an emitter density of 7 nanorods µm-2 and a tapered nanorod morphology generated a high field enhancement factor of 5884. This novel technique shows promise for applications in flat panel display technology.

Flexible NO(x) abatement from power plants in the eastern United States.

PubMed

Sun, Lin; Webster, Mort; McGaughey, Gary; McDonald-Buller, Elena C; Thompson, Tammy; Prinn, Ronald; Ellerman, A Denny; Allen, David T

2012-05-15

Emission controls that provide incentives for maximizing reductions in emissions of ozone precursors on days when ozone concentrations are highest have the potential to be cost-effective ozone management strategies. Conventional prescriptive emissions controls or cap-and-trade programs consider all emissions similarly regardless of when they occur, despite the fact that contributions to ozone formation may vary. In contrast, a time-differentiated approach targets emissions reductions on forecasted high ozone days without imposition of additional costs on lower ozone days. This work examines simulations of such dynamic air quality management strategies for NO(x) emissions from electric generating units. Results from a model of day-specific NO(x) pricing applied to the Pennsylvania-New Jersey-Maryland (PJM) portion of the northeastern U.S. electrical grid demonstrate (i) that sufficient flexibility in electricity generation is available to allow power production to be switched from high to low NO(x) emitting facilities, (ii) that the emission price required to induce EGUs to change their strategies for power generation are competitive with other control costs, (iii) that dispatching strategies, which can change the spatial and temporal distribution of emissions, lead to ozone concentration reductions comparable to other control technologies, and (iv) that air quality forecasting is sufficiently accurate to allow EGUs to adapt their power generation strategies.

Synthesis of Carbon Dots with Multiple Color Emission by Controlled Graphitization and Surface Functionalization.

PubMed

Miao, Xiang; Qu, Dan; Yang, Dongxue; Nie, Bing; Zhao, Yikang; Fan, Hongyou; Sun, Zaicheng

2018-01-01

Multiple-color-emissive carbon dots (CDots) have potential applications in various fields such as bioimaging, light-emitting devices, and photocatalysis. The majority of the current CDots to date exhibit excitation-wavelength-dependent emissions with their maximum emission limited at the blue-light region. Here, a synthesis of multiple-color-emission CDots by controlled graphitization and surface function is reported. The CDots are synthesized through controlled thermal pyrolysis of citric acid and urea. By regulating the thermal-pyrolysis temperature and ratio of reactants, the maximum emission of the resulting CDots gradually shifts from blue to red light, covering the entire light spectrum. Specifically, the emission position of the CDots can be tuned from 430 to 630 nm through controlling the extent of graphitization and the amount of surface functional groups, COOH. The relative photoluminescence quantum yields of the CDots with blue, green, and red emission reach up to 52.6%, 35.1%, and 12.9%, respectively. Furthermore, it is demonstrated that the CDots can be uniformly dispersed into epoxy resins and be fabricated as transparent CDots/epoxy composites for multiple-color- and white-light-emitting devices. This research opens a door for developing low-cost CDots as alternative phosphors for light-emitting devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Time-Resolved Stark Spectroscopy in CdSe Nanoplatelets: Exciton Binding Energy, Polarizability, and Field-Dependent Radiative Rates.

PubMed

Scott, Riccardo; Achtstein, Alexander W; Prudnikau, Anatol V; Antanovich, Artsiom; Siebbeles, Laurens D A; Artemyev, Mikhail; Woggon, Ulrike

2016-10-12

We present a study of the application potential of CdSe nanoplatelets (NPLs), a model system for colloidal 2D materials, as field-controlled emitters. We demonstrate that their emission can be changed by 28% upon application of electrical fields up to 175 kV/cm, a very high modulation depth for field-controlled nanoemitters. From our experimental results we estimate the exciton binding energy in 5.5 monolayer CdSe nanoplatelets to be E B = 170 meV; hence CdSe NPLs exhibit highly robust excitons which are stable even at room temperature. This opens up the possibility to tune the emission and recombination dynamics efficiently by external fields. Our analysis further allows a quantitative discrimination of spectral changes of the emission energy and changes in PL intensity related to broadening of the emission line width as well as changes in the intrinsic radiative rates which are directly connected to the measured changes in the PL decay dynamics. With the developed field-dependent population model treating all occurring field-dependent effects in a global analysis, we are able to quantify, e.g., the ground state exciton transition dipole moment (3.0 × 10 -29 Cm) and its polarizability, which determine the radiative rate, as well as the (static) exciton polarizability (8.6 × 10 -8 eV cm 2 /kV 2 ), all in good agreement with theory. Our results show that an efficient field control over the exciton recombination dynamics, emission line width, and emission energy in these nanoparticles is feasible and opens up application potential as field-controlled emitters.

DEMONSTRATION OF POTENTIAL FOR SELECTIVE CATALYTIC REDUCTION AND DIESEL PARTICULATE FILTERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

McGILL,R; KHAIR, M; SHARP, C

2003-08-24

This project addresses the potential for Selective Catalytic Reduction (SCR) devices (using urea as reductant) together with Diesel Particulate Filters (DPF) and low-pressure loop exhaust gas recirculation (EGR) to achieve future stringent emissions standards for heavy-duty engines powering Class 8 vehicles. Two emission control systems consisting of the three technologies (EGR, SCR, and DPF) were calibrated on a Caterpillar C-12 heavy-duty diesel engine. Results of these calibrations showed good promise in meeting the 2010 heavy-duty emission standards as set forth by the Environmental Protection Agency (EPA). These two emission control systems were developed to evaluate a series of fuels thatmore » have similar formulations except for their sulfur content. Additionally, one fuel, code-named BP15, was also evaluated. This fuel was prepared by processing straight-run distillate stocks through a commercial, single stage hydrotreater employing high activity catalyst at maximum severity. An additional goal of this program is to provide data for an on-going EPA technology review that evaluates progress toward meeting 2007/2010 emission standards. These emissions levels were to be achieved not only on the transient test cycles but in other modes of operation such as the steady-state Euro-III style emission test known as the OICA (Organisation Internationale des Compagnies d'Automobiles) or the ESC (European Stationary Cycle). Additionally, hydrocarbon and carbon monoxide emissions standards are to be met.« less

Lean, premixed, prevaporized fuel combustor conceptual design study

NASA Technical Reports Server (NTRS)

Fiorentino, A. J.; Greene, W.; Kim, J.

1979-01-01

Four combustor concepts, designed for the energy efficient engine, utilize variable geometry or other flow modulation techniques to control the equivalence ratio of the initial burning zone. Lean conditions are maintained at high power to control oxides of nitrogen while near stoichometric conditions are maintained at low power for low CO and THC emissions. Each concept was analyzed and ranked for its potential in meeting the goals of the program. Although the primary goal of the program is a low level of nitric oxide emissions at stratospheric cruise conditions, both the ground level EPA emission standards and combustor performance and operational requirements typical of advanced subsonic aircraft engines are retained as goals as well. Based on the analytical projections made, two of the concepts offer the potential of achieving the emission goals; however, the projected operational characteristics and reliability of any concept to perform satisfactorily over an entire aircraft flight envelope would require extensive experimental substantiation before engine adaptation can be considered.

Primary production control of methane emission from wetlands

NASA Technical Reports Server (NTRS)

Whiting, G. J.; Chanton, J. P.

1993-01-01

Based on simultaneous measurements of CO2 and CH4 exchange in wetlands extending from subarctic peatlands to subtropical marshes, a positive correlation between CH4 emission and net ecosystem production is reported. It is suggested that net ecosystem production is a master variable integrating many factors which control CH4 emission in vegetated wetlands. It is found that about 3 percent of the daily net ecosystem production is emitted back to the atmosphere as CH4. With projected stimulation of primary production and soil microbial activity in wetlands associated with elevated atmospheric CO2 concentration, the potential for increasing CH4 emission from inundated wetlands, further enhancing the greenhouse effect, is examined.

Analyzing and forecasting CO2 emission reduction in China's steel industry

NASA Astrophysics Data System (ADS)

Gao, Chengkang; Wang, Dan; Zhao, Baohua; Chen, Shan; Qin, Wei

2015-03-01

Recent measures of carbon dioxide emissions from the steel industry of China have indicated a high rate of total CO2 emissions from the industry, even compared to the rest of the world. So, CO2 emission reduction in China's steel industry was analyzed, coupling the whole process and scenarios analysis. First, assuming that all available advanced technologies are almost adopted, this study puts forward some key potential-sectors and explores an optimal technical route for reducing CO2 emissions from the Chinese steel industry based on whole process analysis. The results show that in the stages of coking, sintering, and iron making, greater potential for reducing emissions would be fulfilled by taking some technological measures. If only would above well-developed technologies be fulfill, the CO2 emissions from 5 industry production stages would be reduced substantially, and CO2 emissions per ton of steel could be decreased to 1.24 (ton/ton-steel) by 2020. At the same time, the scenarios analysis indicates that if mature carbon-reducing technologies are adopted, and if the difference between steel output growth rate and the GDP growth rate could be controlled below 3%, CO2 emissions from China's steel industry would approach the goal of reducing CO2 emissions per GDP unit by 40%-45% of the 2005 level by 2020. This indicates that the focus of carbon dioxide emissions reduction in China lies in policy adjustments in order to enhance technological application, and lies in reasonably controlling the pace of growth of GDP and steel output.

Adiabatic passage in photon-echo quantum memories

NASA Astrophysics Data System (ADS)

Demeter, Gabor

2013-11-01

Photon-echo-based quantum memories use inhomogeneously broadened, optically thick ensembles of absorbers to store a weak optical signal and employ various protocols to rephase the atomic coherences for information retrieval. We study the application of two consecutive, frequency-chirped control pulses for coherence rephasing in an ensemble with a “natural” inhomogeneous broadening. Although propagation effects distort the two control pulses differently, chirped pulses that drive adiabatic passage can rephase atomic coherences in an optically thick storage medium. Combined with spatial phase-mismatching techniques to prevent primary echo emission, coherences can be rephased around the ground state to achieve secondary echo emission with close to unit efficiency. Potential advantages over similar schemes working with π pulses include greater potential signal fidelity, reduced noise due to spontaneous emission, and better capability for the storage of multiple memory channels.

Impact of elevated CO2, water table, and temperature changes on CO2 and CH4 fluxes from arctic tundra soils

NASA Astrophysics Data System (ADS)

Zona, Donatella; Haynes, Katherine; Deutschman, Douglas; Bryant, Emma; McEwing, Katherine; Davidson, Scott; Oechel, Walter

2015-04-01

Large uncertainties still exist on the response of tundra C emissions to future climate due, in part, to the lack of understanding of the interactive effects of potentially controlling variables on C emissions from Arctic ecosystems. In this study we subjected 48 soil cores (without active vegetation) from dominant arctic wetland vegetation types, to a laboratory manipulation of elevated atmospheric CO2, elevated temperature, and altered water table, representing current and future conditions in the Arctic for two growing seasons. To our knowledge this experiment comprised the most extensively replicated manipulation of intact soil cores in the Arctic. The hydrological status of the soil was the most dominant control on both soil CO2 and CH4 emissions. Despite higher soil CO2 emission occurring in the drier plots, substantial CO2 respiration occurred under flooded conditions, suggesting significant anaerobic respirations in these arctic tundra ecosystems. Importantly, a critical control on soil CO2 and CH4 fluxes was the original vascular plant cover. The dissolved organic carbon (DOC) concentration was correlated with cumulative CH4 emissions but not with cumulative CO2 suggesting C quality influenced CH4 production but not soil CO2 emissions. An interactive effect between increased temperature and elevated CO2 on soil CO2 emissions suggested a potential shift of the soils microbial community towards more efficient soil organic matter degraders with warming and elevated CO2. Methane emissions did not decrease over the course of the experiment, even with no input from vegetation. This result indicated that CH4 emissions are not carbon limited in these C rich soils. Overall CH4 emissions represented about 49% of the sum of total C (C-CO2 + C-CH4) emission in the wet treatments, and 15% in the dry treatments, representing a dominant component of the overall C balance from arctic soils.

Effects of Aftermarket Control Technologies on Gas and ...

EPA Pesticide Factsheets

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 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 semi-volatile organic carbon (OC1) sub-fraction. In addition, results suggest that chemical composition, rather than PM size, is re

Laser-heated emissive plasma probe.

PubMed

Schrittwieser, Roman; Ionita, Codrina; Balan, Petru; Gstrein, Ramona; Grulke, Olaf; Windisch, Thomas; Brandt, Christian; Klinger, Thomas; Madani, Ramin; Amarandei, George; Sarma, Arun K

2008-08-01

Emissive probes are standard tools in laboratory plasmas for the direct determination of the plasma potential. Usually they consist of a loop of refractory wire heated by an electric current until sufficient electron emission. Recently emissive probes were used also for measuring the radial fluctuation-induced particle flux and other essential parameters of edge turbulence in magnetized toroidal hot plasmas [R. Schrittwieser et al., Plasma Phys. Controlled Fusion 50, 055004 (2008)]. We have developed and investigated various types of emissive probes, which were heated by a focused infrared laser beam. Such a probe has several advantages: higher probe temperature without evaporation or melting and thus higher emissivity and longer lifetime, no deformation of the probe in a magnetic field, no potential drop along the probe wire, and faster time response. The probes are heated by an infrared diode laser with 808 nm wavelength and an output power up to 50 W. One probe was mounted together with the lens system on a radially movable probe shaft, and radial profiles of the plasma potential and of its oscillations were measured in a linear helicon discharge.

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...

Michigan`s air emission trading program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russette, T.M.; VanKolken, A.M.

1997-12-31

Michigan`s Emission Trading Program took effect on March 16, 1996 after two years of rule development by the Michigan Department of Environmental Quality, Air Quality Division and affected stakeholders. This program is based on the open market trading model and has been designed to (1) be consistent with existing federal and state rules and regulations, (2) integrate with existing air programs such as the permit program, and (3) address the needs of Michigan`s regulated community. Michigan`s Air Quality Division, along with other interested parties, initiated this program as part of market-based approaches to improve air quality through the reduction ofmore » criteria pollutants (except ozone) and volatile organic compounds. The Emission Trading rules offer potential benefits for Michigan companies that include increased operational flexibility, lower compliance costs, and/or money generated from the sale of the emission reduction credits. The environment also benefits from this program because the rules require that 10 percent of all registered emission reductions must be permanently retired as an air quality benefit. The emission trading program provides new opportunities for consulting firms to assist companies by identifying acceptable ways to generate and use emission reduction credits. Air pollution control companies may also see new opportunities by designing and installing control equipment in order to reduce air emissions. The role of consultants and equipment companies may expand to that of a broker selling and/or buying emission reduction credits on the Emission Trading Registry. Much has been learned since the conception of the air emission trading program. This paper will discuss how the program works in practice compared to what was envisioned in theory and the potential benefits from Michigan`s Emission Trading Program.« less

Arctic shipping emissions inventories and future scenarios

NASA Astrophysics Data System (ADS)

Corbett, J. J.; Lack, D. A.; Winebrake, J. J.; Harder, S.; Silberman, J. A.; Gold, M.

2010-04-01

The Arctic is a sensitive region in terms of climate change and a rich natural resource for global economic activity. Arctic shipping is an important contributor to the region's anthropogenic air emissions, including black carbon - a short-lived climate forcing pollutant especially effective in accelerating the melting of ice and snow. These emissions are projected to increase as declining sea ice coverage due to climate change allows for increased shipping activity in the Arctic. To understand the impacts of these increased emissions, scientists and modelers require high-resolution, geospatial emissions inventories that can be used for regional assessment modeling. This paper presents 5 km×5 km Arctic emissions inventories of important greenhouse gases, black carbon and other pollutants under existing and future (2050) scenarios that account for growth of shipping in the region, potential diversion traffic through emerging routes, and possible emissions control measures. Short-lived forcing of ~4.5 gigagrams of black carbon from Arctic shipping may increase climate forcing; a first-order calculation of global warming potential due to 2030 emissions in the high-growth scenario suggests that short-lived forcing of ~4.5 gigagrams of black carbon from Arctic shipping may increase climate forcing due to Arctic ships by at least 17% compared to warming from these vessels' CO2 emissions (~42 000 gigagrams). The paper also presents maximum feasible reduction scenarios for black carbon in particular. These emissions reduction scenarios will enable scientists and policymakers to evaluate the efficacy and benefits of technological controls for black carbon, and other pollutants from ships.

MERCURY CONTROL IN MUNICIPAL WASTE COMBUSTORS AND COAL-FIRED UTILITIES

EPA Science Inventory

Control of mercury (Hg) emissions from municipal waste combustors (MWCs) and coal-fired utilities has attracted attention due to current and potential regulations. Among several techniques evaluated for Hg control, dry sorbent injection (primarily injection of activated carbon) h...

Environmental and physical controls on northern high latitude methane fluxes across permafrost zones

Treesearch

D. Olefeldt; M.R. Turetsky; P.M. Crill; A.D. McGuire

2013-01-01

Methane (CH4) emissions from the northern high-latitude region represent potentially significant biogeochemical feedbacks to the climate system. We compiled a database of growing-season CH4 emissions from terrestrial ecosystems located across permafrost zones, including 303 sites described in 65 studies. Data on...

FURNACE SORBENT REACTIVITY TESTING FOR CONTROL OF SO2 EMISSIONS FROM ILLINOIS COALS

EPA Science Inventory

Research was undertaken to evaluate the potential of furnai sorbent injection (FSI) for sulf dioxide (S02) emission controlcoal-fired boilers utilizing coals indigenous to Illinois. Tests were run using four coals from the Illinois Basin and six calcium hydroxide [Ca(OH)2], sorbe...

STRATIFICATION OF PARTICULATE AND VOC POLLUTANTS IN PAINT SPRAY BOOTHS

EPA Science Inventory

The paper discusses flow management as part of a joint EPA/U.S. Air Force program on emissions from paint spray booths. he goal of the program is to identify and develop efficienct and economical emissions control concepts for this source. low management is one potential solution...

Potential of Diesel Engine, 1979 Summary Source Document

DOT National Transportation Integrated Search

1980-03-01

This document assesses the fuel economy potential of diesel engines in future passenger cars and light trucks. The primary technologies evaluated include: (1) engine control strategy and implementation, (2) the engine design variables, (3) emissions ...

Performance and Durability Assessment of Two Emission Control Technologies Installed on a Legacy High-Speed Marine Diesel Engine

DTIC Science & Technology

2015-11-05

program investigated cost- effective technologies to reduce emissions from legacy marine engines. High-speed, high-population engine models in both...respectively) were driven by health effects and environmental impacts. The U.S. Navy assessed its contribution to the domestic marine emission inventory...greatest potential. A laboratory developmental assessment was followed by a shipboard evaluation. Effective technology concepts applied to high

Advancing Understanding of Emissions from Oil and Natural ...

EPA Pesticide Factsheets

Executive Summary Environmentally responsible development of oil and gas assets requires well-developed emissions inventories and measurement techniques to verify emissions and the effectiveness of control strategies. To accurately model the oil and gas sector impacts on air quality, it is critical to have accurate activity data, emission factors and chemical speciation profiles for volatile organic compounds (VOCs) and nitrogen oxides (NOx). This report describes a U.S. Environmental Protection Agency (EPA) Office of Research and Development (ORD) Region 8 Regional Applied Research Effort (RARE) effort executed in Fiscal Year (FY) 2014 to FY 2016 that aimed to improve information on upstream oil and production emissions and identify areas where future work is needed. The project involved both field activities and data analysis and synthesis work with emphasis on product-related VOC emissions from well pads. In oil and gas basins with significant condensate and oil production, VOC emissions from well pads primarily arise from the separation of gas and liquid products and the storage process, with the control of emissions usually accomplished by enclosed combustion devices (ECDs), such as flares. Fugitive emissions of VOCs can originate from leaks and from potentially ineffective control systems. In the case of ECDs, byproducts of incomplete combustion may produce more highly reactive ozone precursor species. For both compliance and scientific purposes, the abili

Decrease of VOC emissions from vehicular emissions in Hong Kong from 2003 to 2015: Results from a tunnel study

NASA Astrophysics Data System (ADS)

Cui, Long; Wang, Xiao Liang; Ho, Kin Fai; Gao, Yuan; Liu, Chang; Hang Ho, Steven Sai; Li, Hai Wei; Lee, Shun Cheng; Wang, Xin Ming; Jiang, Bo Qiong; Huang, Yu; Chow, Judith C.; Watson, John G.; Chen, Lung-Wen

2018-03-01

Vehicular emissions are one of major anthropogenic sources of ambient volatile organic compounds (VOCs) in Hong Kong. During the past twelve years, the government of the Hong Kong Special Administrative Region has undertaken a series of air pollution control measures to reduce vehicular emissions in Hong Kong. Vehicular emissions were characterized by repeated measurement in the same roadway tunnel in 2003 and 2015. The total net concentration of measured VOCs decreased by 44.7% from 2003 to 2015. The fleet-average VOC emission factor decreased from 107.1 ± 44.8 mg veh-1 km-1 in 2003 to 58.8 ± 50.7 mg veh-1 km-1 in 2015, and the total ozone (O3) formation potential of measured VOCs decreased from 474.1 mg O3 veh-1 km-1 to 190.8 mg O3 veh-1 km-1. The emission factor of ethene, which is one of the key tracers for diesel vehicular emissions, decreased by 67.3% from 2003 to 2015 as a result of the strict control measures on diesel vehicular emissions. Total road transport VOC emissions is estimated to be reduced by 40% as compared with 2010 by 2020, which will be an important contributor to achieve the goal of total VOC emission reduction in the Pearl River Delta region. The large decrease of VOC emissions from on-road vehicles demonstrates the effectiveness of past multi-vehicular emission control strategy in Hong Kong.

Assessment of alternative disposal methods to reduce greenhouse gas emissions from municipal solid waste in India.

PubMed

Yedla, Sudhakar; Sindhu, N T

2016-06-01

Open dumping, the most commonly practiced method of solid waste disposal in Indian cities, creates serious environment and economic challenges, and also contributes significantly to greenhouse gas emissions. The present article attempts to analyse and identify economically effective ways to reduce greenhouse gas emissions from municipal solid waste. The article looks at the selection of appropriate methods for the control of methane emissions. Multivariate functional models are presented, based on theoretical considerations as well as the field measurements to forecast the greenhouse gas mitigation potential for all the methodologies under consideration. Economic feasibility is tested by calculating the unit cost of waste disposal for the respective disposal process. The purpose-built landfill system proposed by Yedla and Parikh has shown promise in controlling greenhouse gas and saving land. However, these studies show that aerobic composting offers the optimal method, both in terms of controlling greenhouse gas emissions and reducing costs, mainly by requiring less land than other methods. © The Author(s) 2016.

The difference of level CO2 emissions from the transportation sector between weekdays and weekend days on the City Centre of Pemalang

NASA Astrophysics Data System (ADS)

Sawitri, E.; Hardiman, G.; Buchori, I.

2017-06-01

The high growth of human activity potentially increases the number of vehicles and the use of fossil fuels that contribute the increase of CO2 emissions in atmosphere. Controlling CO2 emission that causes greenhouse effect becomes the main agenda of Indonesian Government. The first step control CO2 emissions is by measuring the level of CO2 emissions, especially CO2 emissions from fossil fuel consumption in the transport sector. This research aims to assess the level of CO2 emissions from transportation sector on the main roads in the city centre of Pemalang both in weekdays and weekend days. The methods applied to calculate CO2 emissions using Intergovernmental Panel on Climate Change (IPCC) 2006 method. For this, a survey on the number of vehicles passing through the main roads using hand tally counter is firstly done. The results, CO2 emissions in working day, i.e. 49,006.95 tons/year compared to weekend i.e. 38,865.50 tons/year.

A quantum dot single-photon source with on-the-fly all-optical polarization control and timed emission.

PubMed

Heinze, Dirk; Breddermann, Dominik; Zrenner, Artur; Schumacher, Stefan

2015-10-05

Sources of single photons are key elements for applications in quantum information science. Among the different sources available, semiconductor quantum dots excel with their integrability in semiconductor on-chip solutions and the potential that photon emission can be triggered on demand. Usually, the photon is emitted from a single-exciton ground state. Polarization of the photon and time of emission are either probabilistic or pre-determined by electronic properties of the system. Here, we study the direct two-photon emission from the biexciton. The two-photon emission is enabled by a laser pulse driving the system into a virtual state inside the band gap. From this intermediate state, the single photon of interest is then spontaneously emitted. We show that emission through this higher-order transition provides a versatile approach to generate a single photon. Through the driving laser pulse, polarization state, frequency and emission time of the photon can be controlled on-the-fly.

Drift waves control using emissive cathodes in the laboratory

NASA Astrophysics Data System (ADS)

Plihon, N.; Desangles, V.; De Giorgio, E.; Bousselin, G.; Marino, R.; Pustelnik, N.; Poye, A.

2017-12-01

Low frequency plasma fluctuations are known to be the cause of strong transport perpendicular to magnetic guiding field line. These low frequency drift waves have been studied in linear devices in the laboratory over the last two decades. Their excitation or mitigation have been addressed using different drives, such as ring biasing or electromagnetic low frequency fields. Here we present an experimental characterization of the behavior of drift waves when the profile of the background plasma rotation is controlled using hot emissive cathodes. We show that electron emission from the cathodes modify the plasma potential, which in turn controls the rotation profile. Mitigation or enhancement of drift waves (on the amplitude or azimuthal mode number) is observed depending on the plasma rotation profile.

Analysis of a photon assisted field emission device

NASA Astrophysics Data System (ADS)

Jensen, K. L.; Lau, Y. Y.; McGregor, D. S.

2000-07-01

A field emitter array held at the threshold of emission by a dc gate potential from which current pulses are triggered by the application of a laser pulse on the backside of the semiconductor may produce electron bunches ("density modulation") at gigahertz frequencies. We develop an analytical model of such optically controlled emission from a silicon tip using a modified Wentzel-Kramers-Brillouin and Airy function approach to solving Schrödinger's equation. Band bending and an approximation to the exchange-correlation effects on the image charge potential are included for an array of hyperbolic emitters with a distribution in tip radii and work function. For a simple relationship between the incident photon flux and the resultant electron density at the emission site, an estimation of the tunneling current is made. An example of the operation and design of such a photon-assisted field emission device is given.

Assessment of Pneumatic Controller Emission Measurements using a High Volume Sampler at the Oil and Natural Gas Production Pads in Utah

EPA Science Inventory

Oil and Natural Gas (ONG) production facilities have the potential to emit greenhouse gases such as methane (CH4) and other hydrocarbons (HCs) to the atmosphere. ONG production sites have multiple emission sources including storage tank venting, enclosed combustion devices, engin...

DYNAMIC EVALUATION OF REGIONAL AIR QUALITY MODELS: ASSESSING CHANGES TO O 3 STEMMING FROM CHANGES IN EMISSIONS AND METEOROLOGY

EPA Science Inventory

Regional-scale air quality models are used to estimate the response of air pollutants to potential emission control strategies as part of the decision-making process. Traditionally, the model predicted pollutant concentrations are evaluated for the “base case” to assess a model’s...

40 CFR 63.420 - Applicability.

Code of Federal Regulations, 2012 CFR

2012-07-01

...-CE)+0.17 (TE)+0.08(TES)+0.038(TI)+8.5×10-6(C)+KQ]+0.04(OE) where: ET = emissions screening factor for... efficiency limitation on potential to emit for the vapor processing system used to control emissions from... of external floating roof gasoline storage vessels with only primary seals; TES = total number of...

40 CFR 63.420 - Applicability.

Code of Federal Regulations, 2011 CFR

2011-07-01

...-CE)+0.17 (TE)+0.08(TES)+0.038(TI)+8.5×10-6(C)+KQ]+0.04(OE) where: ET = emissions screening factor for... efficiency limitation on potential to emit for the vapor processing system used to control emissions from... of external floating roof gasoline storage vessels with only primary seals; TES = total number of...

40 CFR 63.420 - Applicability.

Code of Federal Regulations, 2010 CFR

2010-07-01

...-CE)+0.17 (TE)+0.08(TES)+0.038(TI)+8.5×10-6(C)+KQ]+0.04(OE) where: ET = emissions screening factor for... efficiency limitation on potential to emit for the vapor processing system used to control emissions from... of external floating roof gasoline storage vessels with only primary seals; TES = total number of...

40 CFR 63.420 - Applicability.

Code of Federal Regulations, 2013 CFR

2013-07-01

...-CE)+0.17 (TE)+0.08(TES)+0.038(TI)+8.5×10-6(C)+KQ]+0.04(OE) where: ET = emissions screening factor for... efficiency limitation on potential to emit for the vapor processing system used to control emissions from... of external floating roof gasoline storage vessels with only primary seals; TES = total number of...

40 CFR 63.420 - Applicability.

Code of Federal Regulations, 2014 CFR

2014-07-01

...)(1-CE)+0.17 (TE)+0.08(TES)+0.038(TI)+8.5×10-6(C)+KQ]+0.04(OE) where: ET = emissions screening factor... efficiency limitation on potential to emit for the vapor processing system used to control emissions from... of external floating roof gasoline storage vessels with only primary seals; TES = total number of...

Standardized Emission Quantification and Control of Costs for Environmental Measures

NASA Astrophysics Data System (ADS)

Walter, J.; Hustedt, M.; Wesling, V.; Barcikowski, S.

Laser welding and soldering are important industrial joining processes. As is known, LGACs (Laser Generated Air Contaminants) cause costs for environmental measures during production of complex metallic components (steel, aluminium, magnesium, alloys). The hazardous potential of such processes has been assessed by analyzing the specific emissions with respect to relevant threshold limit values (TLVs). Avoiding and controlling emissions caused by laser processing of metals or metal composites is an important task. Using the experimental results, the planning of appropriate exhaust systems for laser processing is facilitated significantly. The costs quantified for environmental measures account for significant percentages of the total manufacturing costs.

Greenhouse gas emission and mitigation potential of changes in water management for two rice sites in Bangladesh

NASA Astrophysics Data System (ADS)

Begum, Khadiza; Kuhnert, Matthias; Yeluripati, Jagadeesh; Smith, Pete; Ogle, Stephen; Parton, William; Kader, Abdul; Sleutel, Steven

2017-04-01

Agriculture is one of the main contributors to greenhouse gas (GHG) emissions in Bangladesh and rice production is one of the largest sources of GHG emissions. This study considers measurements from two test sites, situated in Mymensingh (Bangladesh), to calibrate and validate the biogeochemical model DailyDayCent and estimate the mitigation potential of alternative management practices at the sites. There are two different N application treatments on the two test sites, which are on the first site a control with no N application and a mineral fertilizer application (120 kg N ha-1) and on the second site only a mineral fertilizer application (110 kg N ha-1). For mitigation, the water management is modified in a modelling approach to estimate the mitigation potential for reducing GHG emissions. The model shows partial agreement with the observations. The modifications to the water management, by changing from permanent wetting to alternate wetting, shows a decrease in GHG emissions of up to 46 % and 37 % for the two test sites, respectively. These tests enable an optimization of the management options to reduce the GHG emissions while maintaining yields.

Measurement of air pollutant emissions from Lome, Cotonou and Accra

NASA Astrophysics Data System (ADS)

Lee, James; Vaughan, Adam; Nelson, Bethany; Young, Stuart; Evans, Mathew; Morris, Eleanor; Ladkin, Russel

2017-04-01

High concentrations of airborne pollutants (e.g. the oxides of nitrogen, sulphur dioxide and carbon monoxide) in existing and evolving cities along the Guinea Coast cause respiratory diseases with potentially large costs to human health and the economic capacity of the local workforce. It is important to understand the rate of emission of such pollutants in order to model current and future air quality and provide guidance to the potential outcomes of air pollution abatement strategies. Often dated technologies and poor emission control strategies lead to substantial uncertainties in emission estimates calculated from vehicle and population number density statistics. The unreliable electrical supply in cities in the area has led to an increased reliance on small-scale diesel powered generators and these potentially present a significant source of emissions. The uncontrolled open incineration of waste adds a further very poorly constrained emission source within the cities. The DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa) project involved a field campaign which used highly instrumented aircraft capable of in situ measurements of a range of air pollutants. Seven flights using the UK British Antarctic Survey's Twin Otter aircraft specifically targeted air pollution emissions from cities in West Africa (4 x Accra, Ghana; 2 x Lome, Togo and 1 x Cotonou, Benin). Measurements of NO, NO2, SO2, CO, CH4 and CO2 were made at multiple altitudes upwind and downwind of the cities, with the mass balance technique used to calculate emission rates. These are then compared to the Emissions Database for Global Atmospheric Research (EDGAR) estimates. Ultimately the data will be used to inform on and potentially improve the emission estimates, which in turn should lead to better forecasting of air pollution in West African cities and help guide future air pollution abatement strategy.

Effect of Thaw Depth on Fluxes of CO2 and CH4 in Manipulated Arctic Coastal Tundra of Barrow, Alaska

NASA Astrophysics Data System (ADS)

Kim, Y.

2014-12-01

Changes in CO2 and CH4 emissions represent one of the most significant consequences of drastic climate change in the Arctic, by way of thawing permafrost, a deepened active layer, and decline of thermokarst lakes in the Arctic. This study conducted flux-measurements of CO2 and CH4, as well as environmental factors such as temperature, moisture, and thaw depth, as part of a water table manipulation experiment in the Arctic coastal plain tundra of Barrow, Alaska during autumn. The manipulation treatment consisted of draining, controlling, and flooding treated sections by adjusting standing water. Inundation increased CH4 emission by a factor of 4.3 compared to non-flooded sections. This may be due to the decomposition of organic matter under a limited oxygen environment by saturated standing water. On the other hand, CO2 emission in the dry section was 3.9-fold higher than in others. CH4 emission tends to increase with deeper thaw depth, which strongly depends on the water table; however, CO2 emission is not related to thaw depth. Quotients of global warming potential (GWPCO2) (dry/control) and GWPCH4 (wet/control) increased by 464 and 148 %, respectively, and GWPCH4 (dry/control) declined by 66 %. This suggests that CO2 emission in a drained section is enhanced by soil and ecosystem respiration, and CH4 emission in a flooded area is likely stimulated under an anoxic environment by inundated standing water. The findings of this manipulation experiment during the autumn period demonstrate the different production processes of CO2 and CH4, as well as different global warming potentials, coupled with change in thaw depth. Thus the outcomes imply that the expansion of tundra lakes leads the enhancement of CH4 release, and the disappearance of the lakes causes the stimulated CO2 production in response to the Arctic climate change.

Mixed-Potential NO x and NH 3 Sensors Fabricated by Commercial Manufacturing Methods [Mixed-Potential Sensors NO x and NH 3 Fabricated by Commercial Manufacturing Methods

DOE PAGES

Kreller, Cortney R.; Spernjak, Dusan; Li, Wenxia; ...

2014-08-12

Meeting EPA Tier 3 emissions reduction requirements while simultaneously increasing fuel economy to meet new CAFE standards will require optimization of advanced combustion strategies and emissions control technologies. There is an immediate need for suitable exhaust gas sensor technologies to monitor internal combustion engine tailpipe emissions and to control and maintain efficient operation of the engine and exhaust after treatment systems. NH 3, NO x, and HC sensors could enable onboard diagnostics and combustion control in lean-burn engines, analogous to the role of O 2 sensors in stoichiometric burn engines. Commercial manufacturing methods have been used to fabricate self-heated mixed-potentialmore » sensors in a planar automotive configuration. By altering materials composition and operating conditions, we are able to obtain sensitivity/selectivity to each NH 3, NO x and HCs. In addition, these devices exhibit stable performance over months of testing as a result of the stable morphology of the electrode/electrolyte/gas three-phase interface.« less

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

NASA Astrophysics Data System (ADS)

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

2014-12-01

Tropical savanna covers a large fraction of the global land area and thus may have a substantial effect on the global soil-atmosphere exchange of nitrogen. The pronounced seasonality of hygric conditions in this ecosystem affects strongly microbial process rates in the soil. As these microbial processes control the uptake, production, and release of nitrogen compounds, it is thought that this seasonality finally leads to strong temporal dynamics and varying magnitudes of gaseous losses to the atmosphere. However, given their areal extent and in contrast to other ecosystems, still few in-situ or laboratory studies exist that assess the soil-atmosphere exchange of nitrogen. We present laboratory incubation results from intact soil cores obtained from a natural savanna site in Northern Australia, where N2O, NO, and N2 emissions under controlled environmental conditions were investigated. Furthermore, in-situ measurements of high temporal resolution at this site recorded with automated static and dynamic chamber systems are discussed (N2O, NO). This data is then used to assess the performance of a process-based biogeochemical model (LandscapeDNDC), and the potential magnitude and dynamics of components of the site-scale nitrogen cycle where no measurements exist (biological nitrogen fixation and nitrate leaching). Our incubation results show that severe nutrient limitation of the soil only allows for very low N2O emissions (0.12 kg N ha-1 yr-1) and even a periodic N2O uptake. Annual NO emissions were estimated at 0.68 kg N ha-1 yr-1, while the release of inert nitrogen (N2) was estimated at 6.75 kg N ha-1 yr-1 (data excl. contribution by pulse emissions). We observed only minor N2O pulse emissions after watering the soil cores and initial rain events of the dry to wet season transition in-situ, but short-lived NO pulse emissions were substantial. Interestingly, some cores exhibited a very different N2O emission potential, indicating a substantial spatial variability of potential N release. For most soil moisture and temperature settings, N2 emissions dominated the release of gaseous nitrogen loss (82-99% of total gaseous N loss).

Shipping emission forecasts and cost-benefit analysis of China ports and key regions' control.

PubMed

Liu, Huan; Meng, Zhi-Hang; Shang, Yi; Lv, Zhao-Feng; Jin, Xin-Xin; Fu, Ming-Liang; He, Ke-Bin

2018-05-01

China established Domestic Emission Control Area (DECA) for sulphur since 2015 to constrain the increasing shipping emissions. However, future DECA policy-makings are not supported due to a lack of quantitive evaluations. To investigate the effects of current and possible Chinese DECAs policies, a model is presented for the forecast of shipping emissions and evaluation of potential costs and benefits of an DECA policy package set in 2020. It includes a port-level and regional-level projection accounting for shipping trade volume growth, share of ship types, and fuel consumption. The results show that without control measures, both SO 2 and particulate matter (PM) emissions are expected to increase by 15.3-61.2% in Jing-Jin-Ji, the Yangtze River Delta, and the Pearl River Delta from 2013 to 2020. However, most emissions can be reduced annually by the establishment of a DECA that depends on the size of the control area and the fuel sulphur content limit. Costs range from 0.667 to 1.561 billion dollars (control regional shipping emissions) based on current fuel price. A social cost method shows the regional control scenarios benefit-cost ratios vary from 4.3 to 5.1 with large uncertainty. Chemical transportation model combined with health model method is used to get the monetary health benefits and then compared with the results from social cost method. This study suggests that Chinese DECAs will reduce the projected emissions at a favorable benefit-cost ratio, and furthermore proposes policy combinations that provide high cost-effective benefits as a reference for future policy-making. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.

Role of surface and subsurface processes in scaling N2O emissions along riverine networks

PubMed Central

Marzadri, Alessandra; Dee, Martha M.; Tonina, Daniele; Bellin, Alberto; Tank, Jennifer L.

2017-01-01

Riverine environments, such as streams and rivers, have been reported as sources of the potent greenhouse gas nitrous oxide (N2O) to the atmosphere mainly via microbially mediated denitrification. Our limited understanding of the relative roles of the near-surface streambed sediment (hyporheic zone), benthic, and water column zones in controlling N2O production precludes predictions of N2O emissions along riverine networks. Here, we analyze N2O emissions from streams and rivers worldwide of different sizes, morphology, land cover, biomes, and climatic conditions. We show that the primary source of N2O emissions varies with stream and river size and shifts from the hyporheic–benthic zone in headwater streams to the benthic–water column zone in rivers. This analysis reveals that N2O production is bounded between two N2O emission potentials: the upper N2O emission potential results from production within the benthic–hyporheic zone, and the lower N2O emission potential reflects the production within the benthic–water column zone. By understanding the scaling nature of N2O production along riverine networks, our framework facilitates predictions of riverine N2O emissions globally using widely accessible chemical and hydromorphological datasets and thus, quantifies the effect of human activity and natural processes on N2O production. PMID:28400514

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

2017-07-01

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 NO x emissions and its reduction effect 27 provinces didn't accomplish their corresponding reduction targets. Economic development factor is the dominating driving factor of NO x emissions during the study period, while energy efficiency and technology improvement factors offset total NO x emissions in the majority of provinces. In addition, the industrial structure factor plays a more significant role in reducing the NO x 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 NO x emissions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Impact of policy on greenhouse gas emissions and economics of biodiesel production.

PubMed

Olivetti, Elsa; Gülşen, Ece; Malça, João; Castanheira, Erica; Freire, Fausto; Dias, Luis; Kirchain, Randolph

2014-07-01

As an alternative transportation fuel to petrodiesel, biodiesel has been promoted within national energy portfolio targets across the world. Early estimations of low lifecycle greenhouse gas (GHG) emissions of biodiesel were a driver behind extensive government support in the form of financial incentives for the industry. However, studies consistently report a high degree of uncertainty in these emissions estimates, raising questions concerning the carbon benefits of biodiesel. Furthermore, the implications of feedstock blending on GHG emissions uncertainty have not been explicitly addressed despite broad practice by the industry to meet fuel quality standards and to control costs. This work investigated the impact of feedstock blending on the characteristics of biodiesel by using a chance-constrained (CC) blend optimization method. The objective of the optimization is minimization of feedstock costs subject to fuel standards and emissions constraints. Results indicate that blending can be used to manage GHG emissions uncertainty characteristics of biodiesel, and to achieve cost reductions through feedstock diversification. Simulations suggest that emissions control policies that restrict the use of certain feedstocks based on their GHG estimates overlook blending practices and benefits, increasing the cost of biodiesel. In contrast, emissions control policies which recognize the multifeedstock nature of biodiesel provide producers with feedstock selection flexibility, enabling them to manage their blend portfolios cost effectively, potentially without compromising fuel quality or emissions reductions.

Combustion Dynamics and Control for Ultra Low Emissions in Aircraft Gas-Turbine Engines

NASA Technical Reports Server (NTRS)

DeLaat, John C.

2011-01-01

Future aircraft engines must provide ultra-low emissions and high efficiency at low cost while maintaining the reliability and operability of present day engines. The demands for increased performance and decreased emissions have resulted in advanced combustor designs that are critically dependent on efficient fuel/air mixing and lean operation. However, all combustors, but most notably lean-burning low-emissions combustors, are susceptible to combustion instabilities. These instabilities are typically caused by the interaction of the fluctuating heat release of the combustion process with naturally occurring acoustic resonances. These interactions can produce large pressure oscillations within the combustor and can reduce component life and potentially lead to premature mechanical failures. Active Combustion Control which consists of feedback-based control of the fuel-air mixing process can provide an approach to achieving acceptable combustor dynamic behavior while minimizing emissions, and thus can provide flexibility during the combustor design process. The NASA Glenn Active Combustion Control Technology activity aims to demonstrate active control in a realistic environment relevant to aircraft engines by providing experiments tied to aircraft gas turbine combustors. The intent is to allow the technology maturity of active combustion control to advance to eventual demonstration in an engine environment. Work at NASA Glenn has shown that active combustion control, utilizing advanced algorithms working through high frequency fuel actuation, can effectively suppress instabilities in a combustor which emulates the instabilities found in an aircraft gas turbine engine. Current efforts are aimed at extending these active control technologies to advanced ultra-low-emissions combustors such as those employing multi-point lean direct injection.

Precision tuning of InAs quantum dot emission wavelength by iterative laser annealing

NASA Astrophysics Data System (ADS)

Dubowski, Jan J.; Stanowski, Radoslaw; Dalacu, Dan; Poole, Philip J.

2018-07-01

Controlling the emission wavelength of quantum dots (QDs) over large surface area wafers is challenging to achieve directly through epitaxial growth methods. We have investigated an innovative post growth laser-based tuning procedure of the emission of self-assembled InAs QDs grown epitaxially on InP (001). A targeted blue shift of the emission is achieved with a series of iterative steps, with photoluminescence diagnostics employed between the steps to monitor the result of intermixing. We demonstrate tuning of the emission wavelength of ensembles of QDs to within approximately ±1 nm, while potentially better precision should be achievable for tuning the emission of individual QDs.

Photosynthesis-dependent isoprene emission from leaf to planet in a global carbon-chemistry-climate model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Unger, N.; Harper, K.; Zheng, Y.

2013-10-22

We describe the implementation of a biochemical model of isoprene emission that depends on the electron requirement for isoprene synthesis into the Farquhar/Ball- Berry leaf model of photosynthesis and stomatal conductance that is embedded within a global chemistry-climate simulation framework. The isoprene production is calculated as a function of electron transport-limited photosynthesis, intercellular carbon dioxide concentration, and canopy temperature. The vegetation biophysics module computes the photosynthetic uptake of carbon dioxide coupled with the transpiration of water vapor and the isoprene emission rate at the 30 min physical integration time step of the global chemistry-climate model. In the model, the ratemore » of carbon assimilation provides the dominant control on isoprene emission variability over canopy temperature. A control simulation representative of the present day climatic state that uses plant functional types (PFTs), prescribed phenology and generic PFT-specific isoprene emission potentials (fraction of electrons available for isoprene synthesis) reproduces 50% of the variability across different ecosystems and seasons in a global database of measured campaign-average fluxes. Compared to time-varying isoprene flux measurements at select sites, the model authentically captures the observed variability in the 30 min average diurnal cycle (R 2 = 64-96 %) and simulates the flux magnitude to within a factor of 2. The control run yields a global isoprene source strength of 451 TgC yr -1 that increases by 30% in the artificial absence of plant water stress and by 55% for potential natural vegetation.« less

Photosynthesis-dependent Isoprene Emission from Leaf to Planet in a Global Carbon-chemistry-climate Model

NASA Technical Reports Server (NTRS)

Unger, N.; Harper, K.; Zeng, Y.; Kiang, N. Y.; Alienov, I.; Arneth, A.; Schurgers, G.; Amelynck, C.; Goldstein, A.; Guenther, A.;

Photosynthesis-dependent isoprene emission from leaf to planet in a global carbon-chemistry-climate model

NASA Astrophysics Data System (ADS)

Unger, N.; Harper, K.; Zheng, Y.; Kiang, N. Y.; Aleinov, I.; Arneth, A.; Schurgers, G.; Amelynck, C.; Goldstein, A.; Guenther, A.; Heinesch, B.; Hewitt, C. N.; Karl, T.; Laffineur, Q.; Langford, B.; McKinney, K. A.; Misztal, P.; Potosnak, M.; Rinne, J.; Pressley, S.; Schoon, N.; Serça, D.

2013-10-01

We describe the implementation of a biochemical model of isoprene emission that depends on the electron requirement for isoprene synthesis into the Farquhar-Ball-Berry leaf model of photosynthesis and stomatal conductance that is embedded within a global chemistry-climate simulation framework. The isoprene production is calculated as a function of electron transport-limited photosynthesis, intercellular and atmospheric carbon dioxide concentration, and canopy temperature. The vegetation biophysics module computes the photosynthetic uptake of carbon dioxide coupled with the transpiration of water vapor and the isoprene emission rate at the 30 min physical integration time step of the global chemistry-climate model. In the model, the rate of carbon assimilation provides the dominant control on isoprene emission variability over canopy temperature. A control simulation representative of the present-day climatic state that uses 8 plant functional types (PFTs), prescribed phenology and generic PFT-specific isoprene emission potentials (fraction of electrons available for isoprene synthesis) reproduces 50% of the variability across different ecosystems and seasons in a global database of 28 measured campaign-average fluxes. Compared to time-varying isoprene flux measurements at 9 select sites, the model authentically captures the observed variability in the 30 min average diurnal cycle (R2 = 64-96%) and simulates the flux magnitude to within a factor of 2. The control run yields a global isoprene source strength of 451 TgC yr-1 that increases by 30% in the artificial absence of plant water stress and by 55% for potential natural vegetation.

Photosynthesis-dependent isoprene emission from leaf to planet in a global carbon-chemistry-climate model

NASA Astrophysics Data System (ADS)

Unger, N.; Harper, K.; Zheng, Y.; Kiang, N. Y.; Aleinov, I.; Arneth, A.; Schurgers, G.; Amelynck, C.; Goldstein, A.; Guenther, A.; Heinesch, B.; Hewitt, C. N.; Karl, T.; Laffineur, Q.; Langford, B.; McKinney, K. A.; Misztal, P.; Potosnak, M.; Rinne, J.; Pressley, S.; Schoon, N.; Serça, D.

2013-07-01

We describe the implementation of a biochemical model of isoprene emission that depends on the electron requirement for isoprene synthesis into the Farquhar/Ball-Berry leaf model of photosynthesis and stomatal conductance that is embedded within a global chemistry-climate simulation framework. The isoprene production is calculated as a function of electron transport-limited photosynthesis, intercellular carbon dioxide concentration, and canopy temperature. The vegetation biophysics module computes the photosynthetic uptake of carbon dioxide coupled with the transpiration of water vapor and the isoprene emission rate at the 30 min physical integration time step of the global chemistry-climate model. In the model, the rate of carbon assimilation provides the dominant control on isoprene emission variability over canopy temperature. A control simulation representative of the present day climatic state that uses 8 plant functional types (PFTs), prescribed phenology and generic PFT-specific isoprene emission potentials (fraction of electrons available for isoprene synthesis) reproduces 50% of the variability across different ecosystems and seasons in a global database of 28 measured campaign-average fluxes. Compared to time-varying isoprene flux measurements at 9 select sites, the model authentically captures the observed variability in the 30 min average diurnal cycle (R2= 64-96%) and simulates the flux magnitude to within a factor of 2. The control run yields a global isoprene source strength of 451 Tg C yr-1 that increases by 30% in the artificial absence of plant water stress and by 55% for potential natural vegetation.

Solid state carbon nanotube device for controllable trion electroluminescence emission

NASA Astrophysics Data System (ADS)

Liang, Shuang; Ma, Ze; Wei, Nan; Liu, Huaping; Wang, Sheng; Peng, Lian-Mao

2016-03-01

Semiconducting carbon nanotubes (CNTs) have a direct chirality-dependent bandgap and reduced dimensionality-related quantum confinement effects, which are closely related to the performance of optoelectronic devices. Here, taking advantage of the large energy separations between neutral singlet excitons and charged excitons, i.e. trions in CNTs, we have achieved for the first time all trion electroluminescence (EL) emission from chirality-sorted (8,3) and (8,4) CNT-based solid state devices. We showed that strong trion emission can be obtained as a result of localized impact excitation and electrically injected holes, with an estimated efficiency of ~5 × 10-4 photons per injected hole. The importance of contact-controlled carrier injection (including symmetric and asymmetric contact configurations) and EL spectral stability for gradually increasing bias were also investigated. The realization of electrically induced pure trion emission opens up a new opportunity for CNT film-based optoelectronic devices, providing a new degree of freedom in controlling the devices to extend potential applications in spin or magnetic optoelectronics fields.Semiconducting carbon nanotubes (CNTs) have a direct chirality-dependent bandgap and reduced dimensionality-related quantum confinement effects, which are closely related to the performance of optoelectronic devices. Here, taking advantage of the large energy separations between neutral singlet excitons and charged excitons, i.e. trions in CNTs, we have achieved for the first time all trion electroluminescence (EL) emission from chirality-sorted (8,3) and (8,4) CNT-based solid state devices. We showed that strong trion emission can be obtained as a result of localized impact excitation and electrically injected holes, with an estimated efficiency of ~5 × 10-4 photons per injected hole. The importance of contact-controlled carrier injection (including symmetric and asymmetric contact configurations) and EL spectral stability for gradually increasing bias were also investigated. The realization of electrically induced pure trion emission opens up a new opportunity for CNT film-based optoelectronic devices, providing a new degree of freedom in controlling the devices to extend potential applications in spin or magnetic optoelectronics fields. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07468a

Greenhouse Gas and Noxious Emissions from Dual Fuel Diesel and Natural Gas Heavy Goods Vehicles.

PubMed

Stettler, Marc E J; Midgley, William J B; Swanson, Jacob J; Cebon, David; Boies, Adam M

2016-02-16

Dual fuel diesel and natural gas heavy goods vehicles (HGVs) operate on a combination of the two fuels simultaneously. By substituting diesel for natural gas, vehicle operators can benefit from reduced fuel costs and as natural gas has a lower CO2 intensity compared to diesel, dual fuel HGVs have the potential to reduce greenhouse gas (GHG) emissions from the freight sector. In this study, energy consumption, greenhouse gas and noxious emissions for five after-market dual fuel configurations of two vehicle platforms are compared relative to their diesel-only baseline values over transient and steady state testing. Over a transient cycle, CO2 emissions are reduced by up to 9%; however, methane (CH4) emissions due to incomplete combustion lead to CO2e emissions that are 50-127% higher than the equivalent diesel vehicle. Oxidation catalysts evaluated on the vehicles at steady state reduced CH4 emissions by at most 15% at exhaust gas temperatures representative of transient conditions. This study highlights that control of CH4 emissions and improved control of in-cylinder CH4 combustion are required to reduce total GHG emissions of dual fuel HGVs relative to diesel vehicles.

A Techno-Economic Analysis of Emission Controls on Hydrocarbon Biofuel Production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhatt, Arpit; Zhang, Yimin; Davis, Ryan

Biofuels have the potential to reduce our dependency on petroleum-derived transportation fuels and decrease greenhouse gas (GHG) emissions. Although the overall GHG emissions from biofuels are expected to be lower when compared to those of petroleum fuels, the process of converting biomass feedstocks into biofuels emits various air pollutants, which may be subject to federal air quality regulation or emission limits. While prior research has evaluated the technical and economic feasibility of biofuel technologies, gaps still exist in understanding the regulatory issues associated with the biorefineries and their economic implications on biofuel production costs (referred to as minimum fuel sellingmore » price (MFSP) in this study). The aim of our research is to evaluate the economic impact of implementing emission reduction technologies at biorefineries and estimate the cost effectiveness of two primary control technologies that may be required for air permitting purposes. We analyze a lignocellulosic sugars-to-hydrocarbon biofuel production pathway developed by the National Renewable Energy Laboratory (NREL) and implement air emission controls in Aspen Plus to evaluate how they affect the MFSP. Results from this analysis can help inform decisions about biorefinery siting and sizing, as well as mitigate the risks associated with air permitting.« less

Chemical and toxicological properties of emissions from CNG transit buses equipped with three-way catalysts compared to lean-burn engines and oxidation catalyst technologies

NASA Astrophysics Data System (ADS)

Yoon, Seungju; Hu, Shaohua; Kado, Norman Y.; Thiruvengadam, Arvind; Collins, John F.; Gautam, Mridul; Herner, Jorn D.; Ayala, Alberto

2014-02-01

Chemical and toxicological properties of emissions from compressed natural gas (CNG) fueled transit buses with stoichiometric combustion engines and three-way catalyst (TWC) exhaust control systems were measured using a chassis dynamometer testing facility and compared to the data from earlier CNG engine and exhaust control technologies. Gaseous and particulate matter emissions from buses with stoichiometric engines and TWC were significantly lower than the emissions from buses with lean-burn engines. Carbonyls and volatile organic compounds (VOCs) from buses with stoichiometric engines and TWC were lower by more than 99% compared to buses with lean-burn engines. Elemental and organic carbons (EC and OC), polycyclic aromatic hydrocarbons (PAHs), and trace elements from buses with stoichiometric engines and TWC were effectively controlled and significantly lower than the emissions from buses with lean-burn engines. Potential mutagenicity measured using a microsuspension modification of the Salmonella/microsome assay was lower by more than 99% for buses with stoichiometric engines and TWC, compared to buses with lean-burn engines and OxC.

Precise Design of Phosphorescent Molecular Butterflies with Tunable Photoinduced Structural Change and Dual Emission.

PubMed

Zhou, Chenkun; Tian, Yu; Yuan, Zhao; Han, Mingu; Wang, Jamie; Zhu, Lei; Tameh, Maliheh Shaban; Huang, Chen; Ma, Biwu

2015-08-10

Photoinduced structural change (PSC) is a fundamental excited-state dynamic process in chemical and biological systems. However, precise control of PSC processes is very challenging, owing to the lack of guidelines for designing excited-state potential energy surfaces (PESs). A series of rationally designed butterfly-like phosphorescent binuclear platinum complexes that undergo controlled PSC by Pt-Pt distance shortening and exhibit tunable dual (greenish-blue and red) emission are herein reported. Based on the Bell-Evans-Polanyi principle, it is demonstrated how the energy barrier of the PSC, which can be described as a chemical-reaction-like process between the two energy minima on the first triplet excited-state PES, can be controlled by synthetic means. These results reveal a simple method to engineer the dual emission of molecular systems by manipulating PES to control PSC. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Carbon dioxide efficiency of terrestrial enhanced weathering.

PubMed

Moosdorf, Nils; Renforth, Phil; Hartmann, Jens

2014-05-06

Terrestrial enhanced weathering, the spreading of ultramafic silicate rock flour to enhance natural weathering rates, has been suggested as part of a strategy to reduce global atmospheric CO2 levels. We budget potential CO2 sequestration against associated CO2 emissions to assess the net CO2 removal of terrestrial enhanced weathering. We combine global spatial data sets of potential source rocks, transport networks, and application areas with associated CO2 emissions in optimistic and pessimistic scenarios. The results show that the choice of source rocks and material comminution technique dominate the CO2 efficiency of enhanced weathering. CO2 emissions from transport amount to on average 0.5-3% of potentially sequestered CO2. The emissions of material mining and application are negligible. After accounting for all emissions, 0.5-1.0 t CO2 can be sequestered on average per tonne of rock, translating into a unit cost from 1.6 to 9.9 GJ per tonne CO2 sequestered by enhanced weathering. However, to control or reduce atmospheric CO2 concentrations substantially with enhanced weathering would require very large amounts of rock. Before enhanced weathering could be applied on large scales, more research is needed to assess weathering rates, potential side effects, social acceptability, and mechanisms of governance.

Assessment of secondary sources of Persistent Organic Pollutants in the Arctic

NASA Astrophysics Data System (ADS)

Pisso, Ignacio; Eckhardt, Sabine; Breivik, Knut

2014-05-01

Persistent organic pollutants (POPs) including highly toxic pesticides and other chemicals accumulate in living tissues and magnify in food chains. POPs are subject to long-range transport and hence represent a serious public health issue even in regions where their production is regulated. Rational control strategies require an understanding of the overall relationship between environmental emissions of contaminants and environmental / human exposure. In this study, we assess the relationships between environmental emissions and potential human exposure of organic contaminants with emphasis on long-range atmospheric transport. We investigate whether atmospheric levels of POPs measured at Zeppelin observatory in Svalbard since the early '90s are controlled by primary or secondary emissions. We present statistical indications that the measurements are affected by secondary ocean emissions and discuss the applicability of different inverse modeling approaches.

Dynamics and controls of CO2 and CH4 emissions in the wetland of a montane permafrost region, northeast China

NASA Astrophysics Data System (ADS)

Liu, Xia; Guo, Yuedong; Hu, Haiqing; Sun, Chengkun; Zhao, Xikuan; Wei, Changlei

2015-12-01

To quantify the fluxes and examine the controls on greenhouse gas emissions from the permafrost marshes where the fate of the large quantity of soil organic carbon remains poorly understood, we measured carbon dioxide (CO2) and methane (CH4) emissions in the northern region of the Great Xing'an Mountains, northeast China, in the thawing seasons of 2011 and 2012. The mean CO2 and CH4 fluxes from the marshes were estimated at 403.47 and 0.14 mg m-2 h-1 on average during the two years. Soil temperature was determined as the primary control on the seasonal greenhouse gas emissions during the growing period. The Q10 values, calculated from the exponential regression between soil temperature and CO2 emissions, suggest that the sensitivity of CO2 flux to climate warming has a high spatially variability in the study area. Absorption of atmospheric CH4 was seasonally detected at the sites with lower water table, which confirms the potential of the natural marshes as CH4 sink when water table goes down due to climate change. When viewed from the ecosystem scale, the mean annual water table level and aboveground primary production were deemed as the dominant influencing factors for the mean annual fluxes, which suggests that there were different controls on the gas emissions at different spatial scales. Therefore, the primary controls of the CO2 and CH4 emissions at different spatial scales need to be surveyed in more detail when focusing on the future alteration of greenhouse gas emissions from permafrost marshes due to climate warming.

Control of odor and VOC emissions at wastewater treatment plants: Boston Harbor case study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Getter, R.; Breen, C.; Laquidara, M.

1994-12-31

Siting of the new wastewater treatment plant (WWTP) for the Massachusetts Water Resources Authority (MWRA) in Boston was based on an assumption of mitigation of total reduced sulfur (TRS) and volatile organic compound (VOC) emissions. Collection and treatment of exhaust streams from potential emission sources was recommended. Best Available Control Technology (BACT) for VOC control was conservatively suggested to consist of wet by carbon adsorption based on initial sampling performed in 1988 during facilities planning, which estimated uncontrolled VOC emissions in excess of 1,000 tons per year. This concept was carried forward to the design phase in 1990, concurrent withmore » an extensive air emissions testing and pilot treatment program at the NMRA`s existing primary treatment plant. Results of the pilot program, however, indicated source VOC concentrations well below what was expected as a result of the initial sampling study. Use of the 1990 pilot data in a top-down BACT analysis led to a recommendation to reconsider VOC control with carbon adsorption on the basis of prohibitive cost. This paper summarizes the background and permitting approach for five new odor control facilities on Deer Island for the Boston Harbor Project, with emphasis on the new primary treatment facilities. The paper also presents results from the 1990 emissions characterization and pilot program, providing generally applicable ideas for solving the difficulties of characterizing and estimating emissions for WWTPS. Results from operation of the pilot facilities illustrate the effectiveness of met scrubbing and carbon adsorption in removing TRS and VOCs from wastewater treatment exhaust air streams. In addition, pilot program results indicate the importance of flexibility in design of odor control systems to accommodate variations in concentrations of TRS and VOCS.« less

Practical guide: Tools and methodologies for an oil and gas industry emission inventory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson, C.C.; Killian, T.L.

1996-12-31

During the preparation of Title V Permit applications, the quantification and speciation of emission sources from oil and gas facilities were reevaluated to determine the {open_quotes}potential-to-emit.{close_quotes} The existing emissions were primarily based on EPA emission factors such as AP-42, for tanks, combustion sources, and fugitive emissions from component leaks. Emissions from insignificant activities and routine operations that are associated with maintenance, startups and shutdowns, and releases to control devices also required quantification. To reconcile EPA emission factors with test data, process knowledge, and manufacturer`s data, a careful review of other estimation options was performed. This paper represents the results ofmore » this analysis of emission sources at oil and gas facilities, including exploration and production, compressor stations and gas plants.« less

Tunable light emission by exciplex state formation between hybrid halide perovskite and core/shell quantum dots: Implications in advanced LEDs and photovoltaics.

PubMed

Sanchez, Rafael S; de la Fuente, Mauricio Solis; Suarez, Isaac; Muñoz-Matutano, Guillermo; Martinez-Pastor, Juan P; Mora-Sero, Ivan

2016-01-01

We report the first observation of exciplex state electroluminescence due to carrier injection between the hybrid lead halide perovskite (MAPbI3-xClx) and quantum dots (core/shell PbS/CdS). Single layers of perovskite (PS) and quantum dots (QDs) have been produced by solution processing methods, and their photoluminescent properties are compared to those of bilayer samples in both PS/QD and QD/PS configurations. Exciplex emission at lower energies than the band gap of both PS and QD has been detected. The exciplex emission wavelength of this mixed system can be simply tuned by controlling the QD size. Light-emitting diodes (LEDs) have been fabricated using those configurations, which provide light emission with considerably low turn-on potential. The "color" of the LED can also be tuned by controlling the applied bias. The presence of the exciplex state PS and QDs opens up a broad range of possibilities with important implications not only in tunable LEDs but also in the preparation of intermediate band gap photovoltaic devices with the potentiality of surpassing the Shockley-Queisser limit.

Tunable light emission by exciplex state formation between hybrid halide perovskite and core/shell quantum dots: Implications in advanced LEDs and photovoltaics

PubMed Central

Sanchez, Rafael S.; de la Fuente, Mauricio Solis; Suarez, Isaac; Muñoz-Matutano, Guillermo; Martinez-Pastor, Juan P.; Mora-Sero, Ivan

2016-01-01

We report the first observation of exciplex state electroluminescence due to carrier injection between the hybrid lead halide perovskite (MAPbI3–xClx) and quantum dots (core/shell PbS/CdS). Single layers of perovskite (PS) and quantum dots (QDs) have been produced by solution processing methods, and their photoluminescent properties are compared to those of bilayer samples in both PS/QD and QD/PS configurations. Exciplex emission at lower energies than the band gap of both PS and QD has been detected. The exciplex emission wavelength of this mixed system can be simply tuned by controlling the QD size. Light-emitting diodes (LEDs) have been fabricated using those configurations, which provide light emission with considerably low turn-on potential. The “color” of the LED can also be tuned by controlling the applied bias. The presence of the exciplex state PS and QDs opens up a broad range of possibilities with important implications not only in tunable LEDs but also in the preparation of intermediate band gap photovoltaic devices with the potentiality of surpassing the Shockley-Queisser limit. PMID:26844299

Greenhouse gas emissions from dairy manure management in a Mediterranean environment.

PubMed

Owen, Justine J; Silver, Whendee L

2017-03-01

Livestock agriculture is a major source of anthropogenic greenhouse gas (GHG) emissions, with a substantial proportion of emissions derived from manure management. Accurate estimates of emissions related to management practices and climate are needed for identifying the best approaches to minimize, and potentially mitigate, GHG emissions. Current emissions models such as those of the IPCC, however, are based on emissions factors that have not been broadly tested against field-scale measurements, due to a lack of data. We used a diverse set of measurements over 22 months across a range of substrate conditions on a working dairy to determine patterns and controls on soil-based GHG fluxes. Although dairy soils and substrates differed by management unit, GHG fluxes were poorly predicted by these or climate variables. The manure pile had the greatest GHG emissions, and though temperature increased and O 2 concentration decreased following mixing, we detected almost no change in GHG fluxes due to mixing. Corral fluxes were characterized by hotspots and hot moments driven by patterns in deposition. Annual scraping kept the soil and accumulated manure pack thin, producing drier conditions, particularly in the warm dry season. Summed over area, corral fluxes had the greatest non-CO 2 global warming potential. The field had net CH 4 consumption, but CH 4 uptake was insufficient to offset N 2 O emissions on an area basis. All sites emitted N 2 O with a similar or greater climate impact than CH 4 . Our results highlight the importance of N 2 O emissions, a less commonly measured GHG, from manure management and present potential opportunities for GHG emissions reductions. © 2016 by the Ecological Society of America.

Electron emission phenomena controlled by a transverse electric field in compound emitters

NASA Astrophysics Data System (ADS)

Olesik, Jadwiga; Calusinski, Bogdan; Olesik, Zygmunt

1996-09-01

Influence of an inner electric field on such emission phenomena like: secondary emission, photoemission and field emission has been investigated. The applied sample-emitter was a glass wafer (thickness 0.2 mm) covered on both sides by semiconducting films In2O3:Sn. A voltage (in the interval -2000V divided by 0V) generating transverse electric field was applied to one of the films. This film had a thickness of about 200 nm. The second film (emitting electrons) had a thickness 100 nm or 10 nm. The secondary emission measurements were made by the retarding field method using four grid retarding potential analyzer. It was found that the secondary emission coefficient changes non- monotonically with increasing field intensity. Electron emission measurements without using a primary electron beam were made with the electron multiplier cooperating with a multichannel pulse amplitude analyzer. The measurements were performed in the vacuum of about 2 multiplied by 10-6 Pa. Influence of film thickness on the intensity of field controlled emission and field controlled photoemission was also studied. It was also found that the frequency of counts (generated by electrons in the electron multiplier) depends on the polarizing voltage approximately in an exponential way. Some departures from this dependence can be observed at higher Upol voltages (above 1000 V). Thus, at an appropriate high voltage Upol conditions for a cascade emission are created. At lower voltages the conditions correspond to a semiconductor with a negative electron affinity.

Environmental Assessment for Toxecon Retrofit for Mercury and Multi-Pollutant Control, Presque Isle Power Plant, Marquette, Michigan

DOE Office of Scientific and Technical Information (OSTI.GOV)

N /A

This Environmental Assessment (EA) evaluates environmental issues associated with constructing and operating an integrated emissions control system proposed by We Energies and its project partners with cost-shared funding support by DOE. The proposed project would be demonstrated at the existing 90-MW Units 7, 8, and 9 of We Energies' coal-fired Presque Isle Power Plant in Marquette, Michigan. The commercial-scale demonstrate would allow utilities to make decisions regarding the integrated emissions control system as a viable commercial option. DOE's share of the funding for the 5-year demonstration project would be about $25 million, while $25 million would also be provided bymore » We Energies and its project partners. This project was selected by DOE under the Clean Coal Power Initiative (CCPI) for negotiation of a cooperative agreement to demonstrate the integration of technologies to reduce emissions of mercury (Hg) and particulate matter, as well as potentially control sulfur dioxide (SO{sub 2}), oxides of nitrogen (NO{sub x}) and hydrochloric acid (HCl) emissions. DOE's decision is whether or not to fund the project. The EA evaluates the principal environmental issues, including air quality, waste management, and traffic, that could result from construction and operation of the proposed project. The EA also considers two reasonably foreseeable scenarios that could result from the no-action alternative in which DOE would not provide cost-shared funding for the proposed project. Key findings include that potential air quality impacts resulting from the proposed project would generally be beneficial because plantwide air emissions would decrease or continue at the same level. The decrease in stack exit temperature would decrease the plume rise, which could result in increased downwind ground-level concentrations of those air pollutants experience little or no decrease in stack emissions. However, results of air dispersion modeling indicated that no major impacts would be expected relative to Prevention of Significant Deterioration increments and National Ambient Air Quality Standards.« less

Occupational exposure to diesel and gasoline emissions and lung cancer in Canadian men.

PubMed

Villeneuve, Paul J; Parent, Marie-Élise; Sahni, Vanita; Johnson, Kenneth C

2011-07-01

The International Agency for Research on Cancer classifies diesel exhaust as a probable human carcinogen; this decision is based largely from lung cancer evidence. Gasoline exhaust is classified as a possible carcinogen. Epidemiological studies are needed that improve upon some of the limitations of previous research with respect to the characterization of exposure, and the control for the potential confounding influence of smoking and other occupational exposures. Our objective was to investigate associations between occupational exposure to diesel and gasoline engine emissions and lung cancer. We used a case-control study design that involved men 40 years of age and older at the time of interview. Analyses are based on 1681 incident cases of lung cancer and 2,053 population controls. A self-reported questionnaire elicited a lifetime occupational history, including general tasks, and information on other potential risk factors. Occupational exposures to diesel and gasoline emissions, crystalline silica, and asbestos were assigned to each job held by study subjects by industrial hygienists who were blind to case-control status. Exposure metrics for diesel and gasoline emissions that were modeled included: ever exposure, cumulative exposure, and concentration of exposure. We found a dose-response relationship between cumulative occupational exposure to diesel engine emissions and lung cancer. This association was more pronounced for the squamous and large cell subtypes with adjusted odds ratios across the three increasing tertiles of cumulative lifetime exposure relative to those with no exposure of 0.99, 1.25, and 1.32 (p=0.04) for squamous cell carcinoma, and 1.06, 1.19, 1.68 (p=0.02) for large cell carcinoma. While the association with cumulative exposure to gasoline was weakly positive, it was not statistically significant. Our findings suggest that exposure to diesel engine emissions increases the risk of lung cancer particularly for squamous and large cell carcinoma subtypes. Crown Copyright © 2011. Published by Elsevier Inc. All rights reserved.

How best management practices affect emissions in gas turbine power plants-An important factor to consider when strengthening emission standards.

PubMed

Zeng, Jinghai; Xing, Min; Hou, Min; England, Glenn C; Yan, Jing

2018-04-27

The Beijing Municipal Environmental Protection Bureau (EPB) is considering strengthening the Emission Standard of Air Pollutants for Stationary Gas Turbines, originally published in 2011 (DB11/847-2011), with a focus on reducing nitrogen oxides (NOx) emissions. A feasibility study was conducted to evaluate the current operation of 12 existing combined-cycle gas turbine power plants and the design of two new plants in Beijing and their emission reduction potential, in comparison with a state-of-the-art power plant in California. The study found that best management practices (BMPs) could potentially improve the emission level of the power plants, and should be implemented to minimize emissions under current design characteristics. These BMPs include (1) more frequent tuning of turbine combustors; (2) onsite testing of natural gas characteristics in comparison to turbine manufacturer's specifics and tuning of turbine to natural gas quality; (3) onsite testing of aqueous ammonia to ensure adequate ammonia concentration in the mixed solution, and the purity of the solution; (4) more careful inspection of the heat recovery steam generator (HRSG), and the selective catalytic reduction (SCR) during operation and maintenance; (5) annual testing of the catalyst coupon on the SCR to ensure catalyst effectiveness; and (6) annual ammonia injection grid (AIG) tuning. The study found that without major modification to the plants, improving the management of the Beijing gas turbine power plants may potentially reduce the current hourly average NOx emission level of 5-10 parts per million (ppm; ranges reflects plant variation) by up to 20%. The exact improvement associated with each BMP for each facility requires more detailed analysis, and requires engagement of turbine, HRSG, and SCR manufacturers. This potential improvement is an important factor to consider when strengthening the emission standard. However, note that with the continuous needs of improving air quality within the area, more expensive control measures, such as retrofitting the turbines or the HRSGs, may be considered. This study analyzed the potential emission reductions associated with implementing the best management practices (BMPs) on the combined cycle and cogeneration power plants in Beijing. It determined that implementing the BMPs could potentially achieve up to 580 metric tonnes, or 0.6%, reductions of all NOx emissions in Beijing. Many other cities in China and Asia battling air quality issues may find the information useful in order to evaluate the emission reduction potential of their own gas turbine power plants.

[Method for environmental management in paper industry based on pollution control technology simulation].

PubMed

Zhang, Xue-Ying; Wen, Zong-Guo

2014-11-01

To evaluate the reduction potential of industrial water pollutant emissions and to study the application of technology simulation in pollutant control and environment management, an Industrial Reduction Potential Analysis and Environment Management (IRPAEM) model was developed based on coupling of "material-process-technology-product". The model integrated bottom-up modeling and scenario analysis method, and was applied to China's paper industry. Results showed that under CM scenario, the reduction potentials of waster water, COD and ammonia nitrogen would reach 7 x 10(8) t, 39 x 10(4) t and 0.3 x 10(4) t, respectively in 2015, 13.8 x 10(8) t, 56 x 10(4) t and 0.5 x 10(4) t, respectively in 2020. Strengthening the end-treatment would still be the key method to reduce emissions during 2010-2020, while the reduction effect of structure adjustment would be more obvious during 2015-2020. Pollution production could basically reach the domestic or international advanced level of clean production in 2015 and 2020; the index of wastewater and ammonia nitrogen would basically meet the emission standards in 2015 and 2020 while COD would not.

Impact of Uncertainty from Load-Based Reserves and Renewables on Dispatch Costs and Emissions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Bowen; Maroukis, Spencer D.; Lin, Yashen

2016-11-21

Aggregations of controllable loads are considered to be a fast-responding, cost-efficient, and environmental-friendly candidate for power system ancillary services. Unlike conventional service providers, the potential capacity from the aggregation is highly affected by factors like ambient conditions and load usage patterns. Previous work modeled aggregations of controllable loads (such as air conditioners) as thermal batteries, which are capable of providing reserves but with uncertain capacity. A stochastic optimal power flow problem was formulated to manage this uncertainty, as well as uncertainty in renewable generation. In this paper, we explore how the types and levels of uncertainty, generation reserve costs, andmore » controllable load capacity affect the dispatch solution, operational costs, and CO2 emissions. We also compare the results of two methods for solving the stochastic optimization problem, namely the probabilistically robust method and analytical reformulation assuming Gaussian distributions. Case studies are conducted on a modified IEEE 9-bus system with renewables, controllable loads, and congestion. We find that different types and levels of uncertainty have significant impacts on dispatch and emissions. More controllable loads and less conservative solution methodologies lead to lower costs and emissions.« less

Controllable synthesis of rice-shape Alq3 nanoparticles with single crystal structure

NASA Astrophysics Data System (ADS)

Xie, Wanfeng; Fan, Jihui; Song, Hui; Jiang, Feng; Yuan, Huimin; Wei, Zhixian; Ji, Ziwu; Pang, Zhiyong; Han, Shenghao

2016-10-01

We report the controllable growth of rice-shape nanoparticles of Alq3 by an extremely facile self-assembly approach. Possible mechanisms have been proposed to interpret the formation and controlled process of the single crystal nanoparticles. The field-emission performances (turn-on field 7 V μm-1, maximum current density 2.9 mA cm-2) indicate the potential application on miniaturized nano-optoelectronics devices of Alq3-based. This facile method can potentially be used for the controlled synthesis of other functional complexes and organic nanostructures.

Isolation of Coherent Synchrotron Emission During Relativistic Laser Plasma Interactions

NASA Astrophysics Data System (ADS)

Dromey, B.; Rykovanov, S. G.; Lewis, C. L. S.; Zepf, M.

Coherent Synchrotron Emission (CSE) from relativistic laser plasmas (Pukhov et al., Plas Phys Control Fusion 52:124039, 2010; Dromey et al., Nat Phys 8:804-808, 2012; Dromey et al., New J Phys 15:015025, 2013) has recently been identified as a unique platform for the generation of coherent extreme ultraviolet (XUV) and X-Ray radiation with clear potential for bright attosecond pulse production. Exploiting this potential requires careful selection of interaction geometry, spectral wavelength range and target characteristics to allow the generation of high fidelity single attosecond pulses. In the laboratory the first step on this road is to study the individual mechanisms driving the emission of coherent extreme ultraviolet and X-Ray radiation during laser solid interactions in isolation. Here we show how interactions can be tailored to permit the unambiguous observation of coherent synchrotron emission (CSE) and the implications of this geometry for the resulting harmonic spectrum over the duration of the interaction.

The importance of scattering, surface potential, and vanguard counter-potential in terahertz emission from gallium arsenide

NASA Astrophysics Data System (ADS)

Cortie, D. L.; Lewis, R. A.

2012-06-01

It is well established that under excitation by short (<1 ps), above-band-gap optical pulses, semiconductor surfaces may emit terahertz-frequency electromagnetic radiation via photocarrier diffusion (the dominant mechanism in InAs) or photocarrier drift (dominant in GaAs). Our three-dimensional ensemble Monte Carlo simulations allow multiple physical parameters to vary over wide ranges and provide unique direct insight into the factors controlling terahertz emission. We find for GaAs (in contrast to InAs), scattering and the surface potential are key factors. We further delineate in GaAs (as in InAs) the role of a vanguard counter-potential. The effects of varying dielectric constant, band-gap, and effective mass are similar in both emitter types.

Emissions of terpenoids, benzenoids, and other biogenic gas-phase organic compounds from agricultural crops and their potential implications for air quality

NASA Astrophysics Data System (ADS)

Gentner, D. R.; Ormeño, E.; Fares, S.; Ford, T. B.; Weber, R.; Park, J.-H.; Brioude, J.; Angevine, W. M.; Karlik, J. F.; Goldstein, A. H.

2013-11-01

Agriculture comprises a substantial fraction of land cover in many regions of the world, including California's San Joaquin Valley, which is out of compliance with state and federal standards for tropospheric ozone and particulate matter (PM2.5). Emissions from vegetation and other biogenic and anthropogenic sources react in the atmosphere to produce ozone and secondary organic aerosol, which comprises a substantial fraction of PM2.5. Using data from three measurement campaigns, we examine emissions of reactive gas-phase organic carbon from agricultural crops and their potential to impact regional air quality relative to anthropogenic emissions in California's San Joaquin Valley. Emission rates for a suite of biogenic terpenoid compounds were measured in a greenhouse for 25 representative crops from California in 2008, and ambient measurements of terpenoids and other biogenic compounds in the volatile and intermediate-volatility organic compound range were made over an orange orchard in a rural area of the San Joaquin Valley during two seasons in 2010: summer and spring flowering. When accounting for both emissions of reactive precursors and the deposition of ozone to an orange orchard, the net effect of the orange trees is a net source of ozone in the springtime during flowering, and relatively neutral for most of the summer until the fall when it becomes a sink. Flowering was a major emission event and caused a large increase in emissions including a suite of compounds that had not been measured in the atmosphere before. Such biogenic emission events need to be better parameterized in models as they have significant potential to impact regional air quality since emissions increase by an order of magnitude. In regions like the San Joaquin Valley, the mass of biogenic emissions from agricultural crops during the summer (without flowering) and the potential ozone and secondary organic aerosol formation from these emissions are on the same order as anthropogenic emissions from motor vehicles and must be considered in air quality models and secondary pollution control strategies.

Production, distribution, and cost of oxygenated gasoline blends as a CO control strategy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holmes, J.G; Dworsky, B.S.

1988-01-01

During the past two decades, efforts to reduce the contribution of automotive emissions to air pollution have focused principally on the development of more stringent emission standards for new vehicles, and the use of inspection and maintenance (I/M) programs. Despite the achievements in the last few years, motor vehicles have remained a major source of air pollution in urban areas. Further reductions in either the emission standards or in I/M program pass/fail cutpoints are not politically feasible, and alternative methods to achieve emission reductions are being investigated. One potential method is through the use of alternative fuels that can reducemore » tailpipe emissions. For example, the addition of alcohol or ether into gasoline has been shown to lean out the engine and cut carbon monoxide emissions. This paper compares the costs of producing and distribution methanol, ethanol, and MTBE blends as part of a carbon monoxide control strategy. It addresses the costs of production, distribution, infrastructure development, and retailing associated with each fuel blend.« less

Long-Term Temporal Trends of Polychlorinated Biphenyls and Their Controlling Sources in China.

PubMed

Zhao, Shizhen; Breivik, Knut; Liu, Guorui; Zheng, Minghui; Jones, Kevin C; Sweetman, Andrew J

2017-03-07

Polychlorinated biphenyls (PCBs) are industrial organic contaminants identified as persistent, bioaccumulative, toxic (PBT), and subject to long-range transport (LRT) with global scale significance. This study focuses on a reconstruction and prediction for China of long-term emission trends of intentionally and unintentionally produced (UP) ∑ 7 PCBs (UP-PCBs, from the manufacture of steel, cement and sinter iron) and their re-emissions from secondary sources (e.g., soils and vegetation) using a dynamic fate model (BETR-Global). Contemporary emission estimates combined with predictions from the multimedia fate model suggest that primary sources still dominate, although unintentional sources are predicted to become a main contributor from 2035 for PCB-28. Imported e-waste is predicted to play an increasing role until 2020-2030 on a national scale due to the decline of intentionally produced (IP) emissions. Hypothetical emission scenarios suggest that China could become a potential source to neighboring regions with a net output of ∼0.4 t year -1 by around 2050. However, future emission scenarios and hence model results will be dictated by the efficiency of control measures.

Enhanced winter soil frost reduces methane emission during the subsequent growing season in a boreal peatland.

PubMed

Zhao, Junbin; Peichl, Matthias; Nilsson, Mats B

2016-02-01

Winter climate change may result in reduced snow cover and could, consequently, alter the soil frost regime and biogeochemical processes underlying the exchange of methane (CH4 ) in boreal peatlands. In this study, we investigated the short-term (1-3 years) vs. long-term (11 years) effects of intensified winter soil frost (induced by experimental snow exclusion) on CH4 exchange during the following growing season in a boreal peatland. In the first 3 years (2004-2006), lower CH4 emissions in the treatment plots relative to the control coincided with delayed soil temperature increase in the treatment plots at the beginning of the growing season (May). After 11 treatment years (in 2014), CH4 emissions were lower in the treatment plots relative to the control over the entire growing season, resulting in a reduction in total growing season CH4 emission by 27%. From May to July 2014, reduced sedge leaf area coincided with lower CH4 emissions in the treatment plots compared to the control. From July to August, lower dissolved organic carbon concentrations in the pore water of the treatment plots explained 72% of the differences in CH4 emission between control and treatment. In addition, greater Sphagnum moss growth in the treatment plots resulted in a larger distance between the moss surface and the water table (i.e., increasing the oxic layer) which may have enhanced the CH4 oxidation potential in the treatment plots relative to the control in 2014. The differences in vegetation might also explain the lower temperature sensitivity of CH4 emission observed in the treatment plots relative to the control. Overall, this study suggests that greater soil frost, associated with future winter climate change, might substantially reduce the growing season CH4 emission in boreal peatlands through altering vegetation dynamics and subsequently causing vegetation-mediated effects on CH4 exchange. © 2015 John Wiley & Sons Ltd.

POTENTIAL ABATEMENT PRODUCTION AND MARKETING OF BYPRODUCT SULFURIC ACID IN THE U.S

EPA Science Inventory

The report gives results of an evaluation of the market potential for sulfur and sulfuric acid byproducts of combustion in power plant boilers. (Air quality regulations require control of SOx emissions from power plant boilers. Recovery of sulfur in useful form would avoid waste ...

Diffusion-controlled reference material for VOC emissions testing: proof of concept.

PubMed

Cox, S S; Liu, Z; Little, J C; Howard-Reed, C; Nabinger, S J; Persily, A

2010-10-01

Because of concerns about indoor air quality, there is growing awareness of the need to reduce the rate at which indoor materials and products emit volatile organic compounds (VOCs). To meet consumer demand for low emitting products, manufacturers are increasingly submitting materials to independent laboratories for emissions testing. However, the same product tested by different laboratories can result in very different emissions profiles because of a general lack of test validation procedures. There is a need for a reference material that can be used as a known emissions source and that will have the same emission rate when tested by different laboratories under the same conditions. A reference material was created by loading toluene into a polymethyl pentene film. A fundamental emissions model was used to predict the toluene emissions profile. Measured VOC emissions profiles using small-chamber emissions tests compared reasonably well to the emissions profile predicted using the emissions model, demonstrating the feasibility of the proposed approach to create a diffusion-controlled reference material. To calibrate emissions test chambers and improve the reproducibility of VOC emission measurements among different laboratories, a reference material has been created using a polymer film loaded with a representative VOC. Initial results show that the film's VOC emission profile measured in a conventional test chamber compares well to predictions based on independently determined material/chemical properties and a fundamental emissions model. The use of such reference materials has the potential to build consensus and confidence in emissions testing as well as 'level the playing field' for product testing laboratories and manufacturers.

A systems evaluation on the effectiveness of a catalyst retrofit program in China.

PubMed

Jones, M; Wilson, R; Norbeck, J M; Han, W; Hurley, R; Schuetzle, D

2001-09-01

A low-cost, rare-earth oxide (REO) catalyst has been recommended as part of China's retrofit program for Chinese carbureted vehicles. This study evaluated: (1) the emission reduction efficiency of the REO catalyst during chassis dynamometer testing on the FTP cycle; (2) the effect that fuel properties had on tailpipe emissions and catalyst efficiency; (3) the importance of vehicle premaintenance as part of a retrofit protocol; and (4) the emission reductions obtained following implementation of the program. Results also show that current in-use Chinese noncatalyst, carbureted vehicles operate excessively rich, resulting in extremely high emissions of CO, gaseous toxic compounds, and other non-methane hydrocarbon species (NMHC). Preretrofit maintenance alone has the potential to reduce these emissions by approximately 50%. Dynamometer emission tests showed emissions reductions of >95% for hydrocarbons, CO, and gaseous toxics after retrofit of the REO catalyst. In particular, the relative unit health risk associated with the decrease in emissions of airborne toxic compounds using unleaded Chinese fuel was reduced from 6.33 to 0.30. (Use of low-sulfur California Phase II gasoline rather than current in-use Chinese fuel reduced emissions further.) Following implementation of the program, a follow-up study showed that in-use emissions benefits were considerably less than anticipated, primarily because of poor quality control at the retrofit service centers, a less aggressive preretrofit maintenance procedure, and unauthorized modification to the recommended retrofit control system. Overall results indicate that a carefully controlled retrofit program using REO catalyst technology can reduce emissions significantly. However, well-defined implementation guidelines, and strict adherence to these guidelines are needed to achieve maximum benefits.

Probe into Gaseous Pollution and Assessment of Air Quality Benefit under Sector Dependent Emission Control Strategies over Megacities in Yangtze River Delta, China

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Xinyi; Gao, Yang; Fu, Joshua S.

On February 29th 2012, China published its new National Ambient Air Quality Standard (CH-NAAQS) aiming at revising the standards and measurements for both gaseous pollutants including ozone (O3), nitrogen dioxide (NO2), and sulfur dioxide (SO2), and also particle pollutants including PM10 and PM2.5. In order to understand the air pollution status regarding this new standard, the integrated MM5/CMAQ modeling system was applied over Yangtze River Delta (YRD) within this study to examine the criteria gaseous pollutants listed in the new CH-NAAQS. Sensitivity simulations were also conducted to assess the responses of gaseous pollutants under 8 different sector-dependent emission reduction scenariosmore » in order to evaluate the potential control strategies. 2006 was selected as the simulation year in order to review the air quality condition at the beginning of China’s 11th Five-Year-Plan (FYP, from 2006 to 2010), and also compared with air quality status in 2010 as the end of 11th FYP to probe into the effectiveness of the national emission control efforts. Base case simulation showed distinct seasonal variation for gaseous pollutants: SO2, and NO2 were found to have higher surface concentrations in winter while O3 was found to have higher concentrations in spring and summer than other seasons. According to the analyses focused on 3 megacities within YRD, Shanghai, Nanjing, and Hangzhou, we found different air quality conditions among the cities: NO2 was the primary pollutant that having the largest number of days exceeding the CH-NAAQS daily standard (80 μg/m3) in Shanghai (59 days) and Nanjing (27 days); SO2 was the primary pollutant with maximum number of days exceeding daily air quality standard (150 μg/m3) in Hangzhou (28 days), while O3 exceeding the daily maximum 8-hour standard (160 μg/m3) for relatively fewer days in all the three cities (9 days in Shanghai, 14 days in Nanjing, and 11 days in Hangzhou). Simulation results from predefined potential applicable emission control scenarios suggested significant air quality improvements from emission reduction: 90% of SO2 emission removed from power plant in YRD would be able to reduce more than 85% of SO2 pollution, 85% NOx emission reduction from power plant would reduce more than 60% of NO2 pollution, in terms of reducing the number of days exceeding daily air quality standard. NOx emission reduction from transportation and industry were also found to effectively reduce NO2 pollution but less efficient than emission control from power plants. We also found that multi-pollutants emission control including both NOx and VOC would be a better strategy than independent NOx control over YRD which is China’s 12th Five-Year-Plan (from 2011 to 2015), because O3 pollution would be increased as a side effect of NOx control and counteract NO2 pollution reduction benefit.« less

A case study of the relative effects of power plant nitrogen oxides and sulfur dioxide emission reductions on atmospheric nitrogen deposition.

PubMed

Vijayaraghavan, Krish; Seigneur, Christian; Bronson, Rochelle; Chen, Shu-Yun; Karamchandani, Prakash; Walters, Justin T; Jansen, John J; Brandmeyer, Jo Ellen; Knipping, Eladio M

2010-03-01

The contrasting effects of point source nitrogen oxides (NOx) and sulfur dioxide (SO2) air emission reductions on regional atmospheric nitrogen deposition are analyzed for the case study of a coal-fired power plant in the southeastern United States. The effect of potential emission reductions at the plant on nitrogen deposition to Escambia Bay and its watershed on the Florida-Alabama border is simulated using the three-dimensional Eulerian Community Multiscale Air Quality (CMAQ) model. A method to quantify the relative and individual effects of NOx versus SO2 controls on nitrogen deposition using air quality modeling results obtained from the simultaneous application of NOx and SO2 emission controls is presented and discussed using the results from CMAQ simulations conducted with NOx-only and SO2-only emission reductions; the method applies only to cases in which ambient inorganic nitrate is present mostly in the gas phase; that is, in the form of gaseous nitric acid (HNO3). In such instances, the individual effects of NOx and SO2 controls on nitrogen deposition can be approximated by the effects of combined NOx + SO2 controls on the deposition of NOy, (the sum of oxidized nitrogen species) and reduced nitrogen species (NHx), respectively. The benefit of controls at the plant in terms of the decrease in nitrogen deposition to Escambia Bay and watershed is less than 6% of the overall benefit due to regional Clean Air Interstate Rule (CAIR) controls.

Reactivity-controlled compression ignition drive cycle emissions and fuel economy estimations using vehicle system simulations

DOE PAGES

Curran, Scott J.; Gao, Zhiming; Wagner, Robert M.

2014-12-22

In-cylinder blending of gasoline and diesel to achieve reactivity-controlled compression ignition has been shown to reduce NO X and soot emissions while maintaining or improving brake thermal efficiency as compared with conventional diesel combustion. The reactivity-controlled compression ignition concept has an advantage over many advanced combustion strategies in that the fuel reactivity can be tailored to the engine speed and load, allowing stable low-temperature combustion to be extended over more of the light-duty drive cycle load range. In this paper, a multi-mode reactivity-controlled compression ignition strategy is employed where the engine switches from reactivity-controlled compression ignition to conventional diesel combustionmore » when speed and load demand are outside of the experimentally determined reactivity-controlled compression ignition range. The potential for reactivity-controlled compression ignition to reduce drive cycle fuel economy and emissions is not clearly understood and is explored here by simulating the fuel economy and emissions for a multi-mode reactivity-controlled compression ignition–enabled vehicle operating over a variety of US drive cycles using experimental engine maps for multi-mode reactivity-controlled compression ignition, conventional diesel combustion, and a 2009 port-fuel injected gasoline engine. Drive cycle simulations are completed assuming a conventional mid-size passenger vehicle with an automatic transmission. Multi-mode reactivity-controlled compression ignition fuel economy simulation results are compared with the same vehicle powered by a representative 2009 port-fuel injected gasoline engine over multiple drive cycles. Finally, engine-out drive cycle emissions are compared with conventional diesel combustion, and observations regarding relative gasoline and diesel tank sizes needed for the various drive cycles are also summarized.« less

Dendrochemical assessment of mercury releases from a pond and dredged-sediment landfill impacted by a chlor-alkali plant.

PubMed

Maillard, François; Girardclos, Olivier; Assad, Mohamad; Zappelini, Cyril; Pérez Mena, Julia Maria; Yung, Loïc; Guyeux, Christophe; Chrétien, Stéphane; Bigham, Gary; Cosio, Claudia; Chalot, Michel

2016-07-01

Although current Hg emissions from industrial activities may be accurately monitored, evidence of past releases to the atmosphere must rely on one or more environmental proxies. We used Hg concentrations in tree cores collected from poplars and willows to investigate the historical changes of Hg emissions from a dredged sediment landfill and compared them to a nearby control location. Our results demonstrated the potential value of using dendrochemistry to record historical Hg emissions from past industrial activities. Copyright © 2016 Elsevier Inc. All rights reserved.

Tunable long persistent luminescence in the second near-infrared window via crystal field control.

PubMed

Nie, Jianmin; Li, Yang; Liu, Shanshan; Chen, Qiuqun; Xu, Qi; Qiu, Jianrong

2017-09-29

Construction of an active composite as a biomarker with deeper tissue penetration and higher signal-to-noise ratio (SNR) is of great importance for the application in bioimaging. Here, we report a strategy for tuning the emission bandwidth and intensity via crystal field control in long persistent phosphors (LPPs). Ni 2+ -doped Zn 1+y Sn y Ga 2-x-2y O 4 phosphors, with a tunable emission band peaking from 1270 to 1430 nm in the second near-infrared (NIR) window, have been successfully prepared. Such featured materials have the advantages of low absorption and scattering as well as more efficient tissue penetration. The emission spectra can be controlled by tailoring the local crystal field around the activator precisely via substitution of Zn and Sn for Ga. Moreover, with high resolution and weak light disturbance, these developed multi-band afterglow phosphors exhibit great application potential in advanced optical imaging.

Polarisation-controlled single photon emission at high temperatures from InGaN quantum dots.

PubMed

Wang, T; Puchtler, T J; Zhu, T; Jarman, J C; Nuttall, L P; Oliver, R A; Taylor, R A

2017-07-13

Solid-state single photon sources with polarisation control operating beyond the Peltier cooling barrier of 200 K are desirable for a variety of applications in quantum technology. Using a non-polar InGaN system, we report the successful realisation of single photon emission with a g (2) (0) of 0.21, a high polarisation degree of 0.80, a fixed polarisation axis determined by the underlying crystallography, and a GHz repetition rate with a radiative lifetime of 357 ps at 220 K in semiconductor quantum dots. The temperature insensitivity of these properties, together with the simple planar epitaxial growth method and absence of complex device geometries, demonstrates that fast single photon emission with polarisation control can be achieved in solid-state quantum dots above the Peltier temperature threshold, making this system a potential candidate for future on-chip applications in integrated systems.

Comprehensive assessment of toxic emissions from coal-fired power plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1996-09-01

The 1990 Clean Air Act Amendments (CAAA) have two primary goals: pollution prevention and a market-based least-cost approach to emission control. To address air quality issues as well as permitting and enforcement, the 1990 CAAA contain 11 sections or titles. The individual amendment titles are as follows: Title I - National Ambient Air Quality Standards Title II - Mobile Sources Title III - Hazardous Air Pollutants Title IV - Acid Deposition Control Title V - Permits Title VI - Stratospheric Ozone Protection Chemicals Title VII - Enforcement Title VIII - Miscellaneous Provisions Title IX - Clean Air Research Title Xmore » - Disadvantaged Business Concerns Title XI - Clean Air Employment Transition Assistance Titles I, III, IV, and V will change or have the potential to change how operators of coal-fired utility boilers control, monitor, and report emissions. For the purpose of this discussion, Title III is the primary focus.« less

Identifying potential exposure reduction priorities using regional rankings based on emissions of known and suspected carcinogens to outdoor air in Canada.

PubMed

Setton, Eleanor M; Veerman, Basil; Erickson, Anders; Deschenes, Steeve; Cheasley, Roz; Poplawski, Karla; Demers, Paul A; Keller, C Peter

2015-08-22

Emissions inventories aid in understanding the sources of hazardous air pollutants and how these vary regionally, supporting targeted reduction actions. Integrating information on the relative toxicity of emitted pollutants with respect to cancer in humans helps to further refine reduction actions or recommendations, but few national programs exist in North America that use emissions estimates in this way. The CAREX Canada Emissions Mapping Project provides key regional indicators of emissions (total annual and total annual toxic equivalent, circa 2011) of 21 selected known and suspected carcinogens. The indicators were calculated from industrial emissions reported to the National Pollutant Release Inventory (NPRI) and estimates of emissions from transportation (airports, trains, and car and truck traffic) and residential heating (oil, gas and wood), in conjunction with human toxicity potential factors. We also include substance-specific annual emissions in toxic equivalent kilograms and annual emissions in kilograms, to allow for ranking substances within any region. For provinces and territories in Canada, the indicators suggest the top five substances contributing to the total toxic equivalent emissions in any region could be prioritized for further investigation. Residents of Quebec and New Brunswick may be more at risk of exposure to industrial emissions than those in other regions, suggesting that a more detailed study of exposure to industrial emissions in these provinces is warranted. Residential wood smoke may be an important emission to control, particularly in the north and eastern regions of Canada. Residential oil and gas heating, along with rail emissions contribute little to regional emissions and therefore may not be an immediate regional priority. The developed indicators support the identification of pollutants and sources for additional investigation when planning exposure reduction actions among Canadian provinces and territories, but have important limitations similar to other emissions inventory-based tools. Additional research is required to evaluate how the Emissions Mapping Project is used by different groups and organizations with respect to informing actions aimed at reducing Canadians' potential exposure to harmful air pollutants.

Does Aerosol Geoengineering the Earth's Climate Pass a Cost-Benefit Test?

NASA Astrophysics Data System (ADS)

Keller, K.; Urban, N.; Tuana, N.

2007-12-01

Anthropogenic carbon dioxide (CO2) emissions are changing the Earth's climate with potentially dangerous consequences. Ratified international agreements call for a reduction of CO2 emissions to avoid dangerous anthropogenic interference with the climate system. Recent studies have, however, proposed an alternative strategy: to geoengineer Earth's climate by injecting aerosol precursors into the stratosphere. It is often claimed that aerosol geoengineering would provide net economic benefits because geoengineering requires far lower near-term investments compared to deep cuts in CO2 emissions. However, aerosol geoengineering projects can also cause nontrivial economic costs. This is because aerosol geoengineering hinges on successfully counterbalancing the forcing effects of CO2 emissions (which decay over centuries) with the forcing effects of aerosol emissions (which decay within years). A failure to maintain this delicate balance can lead to abrupt climatic changes, with potentially substantial economic damages. Deferring cuts in CO2 emissions in favor of aerosol geoengineering is hence a deeply uncertain gamble, as it requires so far unknown institutions to reliably control aerosol forcings over centuries. Here we use a simple economic model to evaluate potential costs and benefits of aerosol geoengineering for a wide range of the deeply uncertain parameters. We show that aerosol geoengineering projects may cause economic damages that can far exceed the benefits and may hence fail a cost-benefit test.

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Shaughnessy, Eric; Heeter, Jenny; Keyser, David

Cities are increasingly taking actions such as building code enforcement, urban planning, and public transit expansion to reduce emissions of carbon dioxide in their communities and municipal operations. However, many cities lack the quantitative information needed to estimate policy impacts and prioritize city actions in terms of carbon abatement potential and cost effectiveness. This report fills this research gap by providing methodologies to assess the carbon abatement potential of a variety of city actions. The methodologies are applied to an energy use data set of 23,458 cities compiled for the U.S. Department of Energy’s City Energy Profile tool. The analysismore » estimates the national carbon abatement potential of the most commonly implemented actions in six specific policy areas. The results of this analysis suggest that, in aggregate, cities could reduce nationwide carbon emissions by about 210 million metric tons of carbon dioxide (MMT CO 2) per year in a "moderate abatement scenario" by 2035 and 480 MMT CO 2/year in a "high abatement scenario" by 2035 through these common actions typically within a city’s control in the six policy areas. The aggregate carbon abatement potential of these specific areas equates to a reduction of 3%-7% relative to 2013 U.S. emissions. At the city level, the results suggest the average city could reduce carbon emissions by 7% (moderate) to 19% (high) relative to current city-level emissions. City carbon abatement potential is sensitive to national and state policies that affect the carbon intensity of electricity and transportation. Specifically, the U.S. Clean Power Plan and further renewable energy cost reductions could reduce city carbon emissions overall, helping cities achieve their carbon reduction goals.« less

Demonstration of fuel switching on oceangoing vessels in the Gulf of Mexico.

PubMed

Browning, Louis; Hartley, Seth; Bandemehr, Angela; Gathright, Kenneth; Miller, Wayne

2012-09-01

Switching fuels from high-sulfur heavy fuel oils (HFO) to lower sulfur marine gas oils (MGO) on an oceangoing vessel (OGV) can substantially reduce both PM and SO(x) ship stack emissions, potentially resulting in significant human health and environmental benefits in Gulf of Mexico port communities. The International Maritime Organization (IMO) established an emission control area (ECA) within 200 nautical miles of the US. and Canadian coastlines and French territories off the coast of Canada with lower fuel sulfur standards effective beginning August 2012, where OGVs will need to switch from HFO to MGO. However some operators and other stakeholders, particularly in the Gulf of Mexico, may be unfamiliar with the benefits and requirements and ship operators may be concerned over potential implications for cost and operations. This first-ever US. Environmental Protection Agency (EPA)-sponsored fuel switching demonstration in the Gulf of Mexico was initiated to showcase the environmental and health benefits of as well as operational issues associated with, fuel switching through the following activities: (1) Fuel switching was conducted on typical container ships operating the Gulf of Mexico, as routine fuel switching has been demonstrated in California in recent years. Two vessels were employed in the demonstration: the Maersk Roubaix, which switched fuels entering Port of Houston, TX, and the Port of Progreso, Mexico, and the Hamburg Süd vessel Cap San Lorenzo, which switched fuels entering the Port of Houston and the Mexican Ports of Veracruz and Altamira. Operational and cost aspects were also noted. (2) Emissions reductions were quantified through both a calculation approach based on fuel use of the Maersk Line vessel Roubaix and in-stack monitoring of emissions from the Hamburg Süd Cap San Lorenzo. Pollutant emissions including PM, SO(x), NO(x), and PM component speciation were sampled during use of both fuels. These observations showed reductions (1-6%) in NO(x) and substantial reductions in PM (50-70%) and SO(x) (> 99%) depending on engine and load. (3) Emission inventories at three ports were calculated. (4) Potential health and environmental benefits to communities and ecosystems in the Gulf of Mexico were estimated through screening-level modeling of air dispersion and atmospheric deposition of ship emissions at the Port of Veracruz to indicate the substantial reductions available through fuel switching. The United States and Canada have recently adopted a North American Emission Control Area that will require a shift from high-sulfur to low-sulfur fuels in the marine transportation sector. Cleaner fuels are expected to reduce sulfur and particulate emissions. This paper verifies the feasibility of such switching operations, the potential to reduce emissions if extended to the Gulf of Mexico, and the associated environmental impacts of these emission reductions inland and to sensitive ecosystems.

COMBUSTION ADDITIVES FOR POLLUTION CONTROL - A STATE-OF-THE-ART REVIEW

EPA Science Inventory

The report is a state-of-the-art review of the potential of combustion-type fuel additives in reducing air pollutant emissions from oil and coal firing. It contains two complementary parts: a review of the relation of combustion mechanisms to additive action in controlling emissi...

Impacts of integrated nutrient management on methane emission, global warming potential and carbon storage capacity in rice grown in a northeast India soil.

PubMed

Bharali, Ashmita; Baruah, Kushal Kumar; Baruah, Sunitee Gohain; Bhattacharyya, Pradip

2018-02-01

Rice soil is a source of emission of two major greenhouse gases (methane (CH 4 ) and nitrous oxide (N 2 O)) and a sink of carbon dioxide (CO 2 ). The effect of inorganic fertilizers in combination with various organics (cow dung, green manure (Sesbania aculeata) Azolla compost, rice husk) on CH 4 emission, global warming potential, and soil carbon storage along with crop productivity were studied at university farm under field conditions. The experiment was conducted in a randomized block design for 2 years in a monsoon rice (cv. Ranjit) ecosystem (June-November, 2014 and 2015). Combined application of inorganic (NPK) with Sesbania aculeata resulted in high global warming potential (GWP) of 887.4 kg CO 2 ha -1 and low GWP of 540.6 kg CO 2 ha -1 was recorded from inorganic fertilizer applied field. Irrespective of the type of organic amendments, flag leaf photosynthesis of the rice crop increased over NPK application (control). There was an increase in CH 4 emission from the organic amended fields compared to NPK alone. The combined application of NPK and Azolla compost was effective in the buildup of soil carbon (16.93 g kg -1 ) and capacity of soil carbon storage (28.1 Mg C ha -1 ) with high carbon efficiency ratio (16.9). Azolla compost application along with NPK recorded 15.66% higher CH 4 emission with 27.43% yield increment over control. Azolla compost application significantly enhanced carbon storage of soil and improved the yielding ability of grain (6.55 Mg ha -1 ) over other treatments.

Emissions inventory and scenario analyses of air pollutants in Guangdong Province, China

NASA Astrophysics Data System (ADS)

Chen, Hui; Meng, Jing

2017-03-01

Air pollution, causing significantly adverse health impacts and severe environmental problems, has raised great concerns in China in the past few decades. Guangdong Province faces major challenges to address the regional air pollution problem due to the lack of an emissions inventory. To fill this gap, an emissions inventory of primary fine particles (PM2.5) is compiled for the year 2012, and the key precursors (sulfur dioxide, nitrogen oxides) are identified. Furthermore, policy packages are simulated during the period of 2012‒2030 to investigate the potential mitigation effect. The results show that in 2012, SO2, NO x , and PM2.5 emissions in Guangdong Province were as high as (951.7, 1363.6, and 294.9) kt, respectively. Industrial production processes are the largest source of SO2 and PM2.5 emissions, and transport is the top contributor of NO x emissions. Both the baseline scenario and policy scenario are constructed based on projected energy growth and policy designs. Under the baseline scenario, SO2, NO x , and PM2.5 emissions will almost double in 2030 without proper emissions control policies. The suggested policies are categorized into end-of- pipe control in power plants (ECP), end-of-pipe control in industrial processes (ECI), fuel improvement (FI), energy efficiency improvement (EEI), substitution-pattern development (SPD), and energy saving options (ESO). With the implementation of all these policies, SO2, NO x , and PM2.5 emissions are projected to drop to (303.1, 585.4, and 102.4) kt, respectively, in 2030. This inventory and simulated results will provide deeper insights for policy makers to understand the present situation and the evolution of key emissions in Guangdong Province.

Acidifier application rate impacts on ammonia emissions from US roaster chicken houses

NASA Astrophysics Data System (ADS)

Shah, Sanjay B.; Grimes, Jesse L.; Oviedo-Rondón, Edgar O.; Westerman, Philip W.

2014-08-01

Due to its potential environmental and public health impacts, emissions of ammonia (NH3) as well as several other gases from US livestock farms may be regulated. Broiler houses are important sources of NH3 emissions. However, there are no emissions data from roaster (8-12 wk old broilers, ˜4 kg ea.) houses. Producers treat the litter in broiler houses with acidifiers, such as sodium bisulfate (SBS, NaHSO4) to reduce ammonia production and protect bird health. However, there is very little data on the effect of acidifiers, particularly at high application rates on ammonia emissions. The impact of different SBS application rates [High (0.95-1.46 kg m-2, whole house), Medium (0.73 kg m-2, whole house), Low (0.37-0.49 kg m-2, whole house), and Control (0.37-0.49 kg m-2, brood chamber)] on ammonia emissions was evaluated in commercial roaster houses over 22 months spanning eight flocks. Ammonia emission from each fan was measured with an acid scrubber that operated only when the fan operated. Emissions were calculated using >95% measured data with the rest being estimated using robust methods. Exhaust ammonia-N concentrations were inversely correlated with the SBS application rates. Emission rates on animal unit (AU, where 1 AU = 500 kg live-mass) basis (ER, g d-1 AU-1) were reduced by 27, 13, and 5%, respectively, in the High, Medium, and Low treatments vs. the Control treatment (mean: 100 g d-1 AU-1, range: 86-114 g d-1 AU-1). Emission rates for the Control treatment measured in this study on roasters were mostly higher than ERs in the literature. Differences in ERs are not only due to diet, environmental and management conditions, but also due to measurement methods.

Green house gas emissions from composting and mechanical biological treatment.

PubMed

Amlinger, Florian; Peyr, Stefan; Cuhls, Carsten

2008-02-01

In order to carry out life-cycle assessments as a basis for far-reaching decisions about environmentally sustainable waste treatment, it is important that the input data be reliable and sound. A comparison of the potential greenhouse gas (GHG) emissions associated with each solid waste treatment option is essential. This paper addresses GHG emissions from controlled composting processes. Some important methodological prerequisites for proper measurement and data interpretation are described, and a common scale and dimension of emission data are proposed so that data from different studies can be compared. A range of emission factors associated with home composting, open windrow composting, encapsulated composting systems with waste air treatment and mechanical biological waste treatment (MBT) are presented from our own investigations as well as from the literature. The composition of source materials along with process management issues such as aeration, mechanical agitation, moisture control and temperature regime are the most important factors controlling methane (CH4), nitrous oxide (N2O) and ammoniac (NH3) emissions. If ammoniac is not stripped during the initial rotting phase or eliminated by acid scrubber systems, biofiltration of waste air provides only limited GHG mitigation, since additional N2O may be synthesized during the oxidation of NH3, and only a small amount of CH4 degradation occurs in the biofilter. It is estimated that composting contributes very little to national GHG inventories generating only 0.01-0.06% of global emissions. This analysis does not include emissions from preceding or post-treatment activities (such as collection, transport, energy consumption during processing and land spreading), so that for a full emissions account, emissions from these activities would need to be added to an analysis.

Thermal Emission Control via Bandgap Engineering in Aperiodically Designed Nanophotonic Devices.

PubMed

Maciá, Enrique

2015-05-20

Aperiodic photonic crystals can open up novel routes for more efficient photon management due to increased degrees of freedom in their design along with the unique properties brought about by the long-range aperiodic order as compared to their periodic counterparts. In this work we first describe the fundamental notions underlying the idea of thermal emission/absorption control on the basis of the systematic use of aperiodic multilayer designs in photonic quasicrystals. Then, we illustrate the potential applications of this approach in order to enhance the performance of daytime radiative coolers and solar thermoelectric energy generators.

Thermal Emission Control via Bandgap Engineering in Aperiodically Designed Nanophotonic Devices

PubMed Central

Maciá, Enrique

2015-01-01

Aperiodic photonic crystals can open up novel routes for more efficient photon management due to increased degrees of freedom in their design along with the unique properties brought about by the long-range aperiodic order as compared to their periodic counterparts. In this work we first describe the fundamental notions underlying the idea of thermal emission/absorption control on the basis of the systematic use of aperiodic multilayer designs in photonic quasicrystals. Then, we illustrate the potential applications of this approach in order to enhance the performance of daytime radiative coolers and solar thermoelectric energy generators. PMID:28347037

Refining Field Measurements of Methane Flux Rates from Abandoned Oil and Gas Wells

NASA Astrophysics Data System (ADS)

Lagron, C. S.; Kang, M.; Riqueros, N. S.; Jackson, R. B.

2015-12-01

Recent studies in Pennsylvania demonstrate the potential for significant methane emissions from abandoned oil and gas wells. A subset of tested wells was high emitting, with methane flux rates up to seven orders of magnitude greater than natural fluxes (up to 105 mg CH4/hour, or about 2.5LPM). These wells contribute disproportionately to the total methane emissions from abandoned oil and gas wells. The principles guiding the chamber design have been developed for lower flux rates, typically found in natural environments, and chamber design modifications may reduce uncertainty in flux rates associated with high-emitting wells. Kang et al. estimate errors of a factor of two in measured values based on previous studies. We conduct controlled releases of methane to refine error estimates and improve chamber design with a focus on high-emitters. Controlled releases of methane are conducted at 0.05 LPM, 0.50 LPM, 1.0 LPM, 2.0 LPM, 3.0 LPM, and 5.0 LPM, and at two chamber dimensions typically used in field measurements studies of abandoned wells. As most sources of error tabulated by Kang et al. tend to bias the results toward underreporting of methane emissions, a flux-targeted chamber design modification can reduce error margins and/or provide grounds for a potential upward revision of emission estimates.

The effects of electronic cigarette emissions on systemic cotinine levels, weight and postnatal lung growth in neonatal mice.

PubMed

McGrath-Morrow, Sharon A; Hayashi, Madoka; Aherrera, Angela; Lopez, Armando; Malinina, Alla; Collaco, Joseph M; Neptune, Enid; Klein, Jonathan D; Winickoff, Jonathan P; Breysse, Patrick; Lazarus, Philip; Chen, Gang

2015-01-01

Electronic cigarette (E-cigarettes) emissions present a potentially new hazard to neonates through inhalation, dermal and oral contact. Exposure to nicotine containing E-cigarettes may cause significant systemic absorption in neonates due to the potential for multi-route exposure. Systemic absorption of nicotine and constituents of E-cigarette emissions may adversely impact weight and lung development in the neonate. To address these questions we exposed neonatal mice to E-cigarette emissions and measured systemic cotinine levels and alveolar lung growth. Neonatal mice were exposed to E-cigarettes for the first 10 days of life. E-cigarette cartridges contained either 1.8% nicotine in propylene glycol (PG) or PG vehicle alone. Daily weights, plasma and urine cotinine levels and lung growth using the alveolar mean linear intercept (MLI) method were measured at 10 days of life and compared to room air controls. Mice exposed to 1.8% nicotine/PG had a 13.3% decrease in total body weight compared to room air controls. Plasma cotinine levels were found to be elevated in neonatal mice exposed to 1.8% nicotine/PG E-cigarettes (mean 62.34± 3.3 ng/ml). After adjusting for sex and weight, the nicotine exposed mice were found to have modestly impaired lung growth by MLI compared to room air control mice (p<.054 trial 1; p<.006 trial 2). These studies indicate that exposure to E-cigarette emissions during the neonatal period can adversely impact weight gain. In addition exposure to nicotine containing E-cigarettes can cause detectable levels of systemic cotinine, diminished alveolar cell proliferation and a modest impairment in postnatal lung growth.

Experimental assessment of the potential to decrease diesel NOx emissions beyond minimum requirements for Euro 6 Real Drive Emissions (RDE) compliance.

PubMed

Triantafyllopoulos, Georgios; Katsaounis, Dimitrios; Karamitros, Dimitrios; Ntziachristos, Leonidas; Samaras, Zissis

2018-03-15

The objective of this study was to test the potential for NO x emissions improvements on a typical Euro 6 diesel vehicle, following modifications to its emissions control system, under Real Drive Emissions (RDE) testing conditions. A commercially available car was selected and was first measured in its original configuration according to RDE on the road and an initial conformity factor (CF) of 5.4 was determined. Subsequent engine calibration and installation of a Selective Catalytic Reduction (SCR) device were conducted and tested on a fully transient engine dyno setup, which precisely reproduced the engine operation under the on-road RDE test. The NO x reduction achieved with those upgrades was 90%, leading to a CF of 0.53, with no CO 2 or fuel consumption penalty. These findings demonstrate that diesel vehicles can reach low NO x levels under real world driving conditions, when well-designed modern exhaust aftertreatment components are installed and properly calibrated. Copyright © 2017 Elsevier B.V. All rights reserved.

Aqueous synthesis of L-cysteine and mercaptopropionic acid co-capped ZnS quantum dots with dual emissions

NASA Astrophysics Data System (ADS)

Ren, Yingkun; Wang, Yongbo; Yang, Min; Liu, Enzhou; Hu, Xiaoyun; Zhang, Xu; Fan, Jun

2018-07-01

In this paper, L-cysteine (L-cys) and mercaptopropionic acid (MPA) co-capped ZnS quantum dots (QDs) with dual emissions have been successfully synthesized by a one-pot aqueous-phase synthesis method. The intensities of the dual emissions could be controlled by regulating the molar ratio of L-cys to MPA, and the fluorescence color also turned from blue to yellow accordingly. The relationship between the ligands and fluorescence was investigated and the results indicated that L-cys could cause two emissions and MPA improved the emission intensity. In addition, the L-cys-MPA co-capped ZnS QDs showed high photostability under UV irradiation. Therefore, the L-cys-MPA co-capped ZnS QDs, which show the dual emissions and tunable emission intensities, have great potentials for use in ratiometric fluorescence sensors and multicolor bioimaging.

40 CFR 264.301 - Design and operating requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... other factors which would influence the quality and mobility of the leachate produced and the potential... emission controls or metal casting molding sand, and such wastes do not contain constituents which would...

Geochemical Impacts to Groundwater from Geologic Carbon Sequestration: Controls on pH and Inorganic Carbon Concentrations from Reaction Path and Kinetic Modeling

EPA Science Inventory

Geologic carbon sequestration has the potential to cause long-term reductions in global emissions of carbon dioxide to the atmosphere. Safe and effective application of carbon sequestration technology requires an understanding of the potential risks to the quality of underground...

Minimizing the health and climate impacts of emissions from heavy-duty public transportation bus fleets through operational optimization.

PubMed

Gouge, Brian; Dowlatabadi, Hadi; Ries, Francis J

2013-04-16

In contrast to capital control strategies (i.e., investments in new technology), the potential of operational control strategies (e.g., vehicle scheduling optimization) to reduce the health and climate impacts of the emissions from public transportation bus fleets has not been widely considered. This case study demonstrates that heterogeneity in the emission levels of different bus technologies and the exposure potential of bus routes can be exploited though optimization (e.g., how vehicles are assigned to routes) to minimize these impacts as well as operating costs. The magnitude of the benefits of the optimization depend on the specific transit system and region. Health impacts were found to be particularly sensitive to different vehicle assignments and ranged from worst to best case assignment by more than a factor of 2, suggesting there is significant potential to reduce health impacts. Trade-offs between climate, health, and cost objectives were also found. Transit agencies that do not consider these objectives in an integrated framework and, for example, optimize for costs and/or climate impacts alone, risk inadvertently increasing health impacts by as much as 49%. Cost-benefit analysis was used to evaluate trade-offs between objectives, but large uncertainties make identifying an optimal solution challenging.

Ozone changes in response to the heavy-duty diesel truck control in the Pearl River Delta

NASA Astrophysics Data System (ADS)

Yu, Xin; Yuan, Zibing; Fung, J. C. H.; Xue, Jian; Li, Ying; Zheng, Junyu; Lau, A. K. H.

2014-05-01

In recent years, restricting heavy-duty diesel trucks from driving within urban areas during the daytime is implemented in major PRD cities (e.g. Guangzhou and Shenzhen). Potential effects of this traffic control policy on spatial and temporal variations of O3 concentrations are examined by CMAQ model system. Temporal profiles of mobile source emissions are modified to reflect the emission characteristics after the control. Our results show that: (1) with the updated mobile emission profile, there is a notable improvement in O3 simulation performance for urban sites, with reductions in both the nighttime O3 overestimation (up to 25 ppb) and the daytime underestimation on O3 peak values (up to 20 ppb); (2) although the control policies are only applied in urban locations, their effects may extend to much larger downwind areas. The results from this study provide basic information that is useful in understanding the effects of mobile control policies on ambient O3 in highly developing regions of China where similar strategies have been widely implemented.

Nitrous oxide production from temperate and tropical oyster species in response to nutrient loading

NASA Astrophysics Data System (ADS)

Chan, H.; Garate, M.; Moseman-Valtierra, S.

2016-02-01

Anthropogenic pollution, such as nitrogen (N), has the potential to increase greenhouse gas (GHG) emissions in marine ecosystems. Some organisms can be used as important biological indicators for GHG emissions to their environment based on their feeding habits. With large inputs of these anthropogenic pollutants, emissions of nitrous oxide (N2O), a potent GHG, can be potentially increased from temperate invertebrates, though not much is known about tropical invertebrates. Thus, we compared N2O emissions in response to N additions from the temperate oyster species Crassostrea virginica and compared it to a tropical species, Isognomon alatus, found in Puerto Rico. Oysters were exposed to two seawater treatments: (1) no nutrient addition (control) and (2) 100µM ammonium nitrate. Each treatment had 4-5 replicates. Measurements for dissolved N2O and nutrients were taken at the start of the incubation and then at two, four, and five hours by collecting water samples of each tank. Dissolved N2O concentrations were analyzed using gas chromatography. We hypothesized that the N addition treatment would produce more N2O for both Rhode Island and Puerto Rico. We found that there was no significant difference between the control and N enriched treatments for C. virginica over the short timespan, although the N enriched treatment did have a steady trend in increasing in N2O concentration over time. Further analysis is needed for the I. alatus, though we expect an increase in N2O emissions due to warmer water temperatures, which might enhance microbial metabolism and production of N2O. This differs from work previously done in a long-term experiment on C. virginica, which showed that N2O significantly in the N enriched treatment over 28-days. Our study shows that short-term pulses of N may not potentially increase N2O emissions, though further analysis is needed for longer-term exposures.

Effect of biogas generation on radon emissions from landfills receiving radium-bearing waste from shale gas development.

PubMed

Walter, Gary R; Benke, Roland R; Pickett, David A

2012-09-01

Dramatic increases in the development of oil and natural gas from shale formations will result in large quantities of drill cuttings, flowback water, and produced water. These organic-rich shale gas formations often contain elevated concentrations of naturally occurring radioactive materials (NORM), such as uranium, thorium, and radium. Production of oil and gas from these formations will also lead to the development of technologically enhanced NORM (TENORM) in production equipment. Disposal of these potentially radium-bearing materials in municipal solid waste (MSW) landfills could release radon to the atmosphere. Risk analyses of disposal of radium-bearing TENORM in MSW landfills sponsored by the Department of Energy did not consider the effect of landfill gas (LFG) generation or LFG control systems on radon emissions. Simulation of radon emissions from landfills with LFG generation indicates that LFG generation can significantly increase radon emissions relative to emissions without LFG generation, where the radon emissions are largely controlled by vapor-phase diffusion. Although the operation of LFG control systems at landfills with radon source materials can result in point-source atmospheric radon plumes, the LFG control systems tend to reduce overall radon emissions by reducing advective gas flow through the landfill surface, and increasing the radon residence time in the subsurface, thus allowing more time for radon to decay. In some of the disposal scenarios considered, the radon flux from the landfill and off-site atmospheric activities exceed levels that would be allowed for radon emissions from uranium mill tailings. Increased development of hydrocarbons from organic-rich shale formations has raised public concern that wastes from these activities containing naturally occurring radioactive materials, particularly radium, may be disposed in municipal solid waste landfills and endanger public health by releasing radon to the atmosphere. This paper analyses the processes by which radon may be emitted from a landfill to the atmosphere. The analyses indicate that landfill gas generation can significantly increase radon emissions, but that the actual level of radon emissions depend on the place of the waste, construction of the landfill cover, and nature of the landfill gas control system.

Active Combustion Control for Aircraft Gas-Turbine Engines-Experimental Results for an Advanced, Low-Emissions Combustor Prototype

NASA Technical Reports Server (NTRS)

DeLaat, John C.; Kopasakis, George; Saus, Joseph R.; Chang, Clarence T.; Wey, Changlie

2012-01-01

Lean combustion concepts for aircraft engine combustors are prone to combustion instabilities. Mitigation of instabilities is an enabling technology for these low-emissions combustors. NASA Glenn Research Center s prior activity has demonstrated active control to suppress a high-frequency combustion instability in a combustor rig designed to emulate an actual aircraft engine instability experience with a conventional, rich-front-end combustor. The current effort is developing further understanding of the problem specifically as applied to future lean-burning, very low-emissions combustors. A prototype advanced, low-emissions aircraft engine combustor with a combustion instability has been identified and previous work has characterized the dynamic behavior of that combustor prototype. The combustor exhibits thermoacoustic instabilities that are related to increasing fuel flow and that potentially prevent full-power operation. A simplified, non-linear oscillator model and a more physics-based sectored 1-D dynamic model have been developed to capture the combustor prototype s instability behavior. Utilizing these models, the NASA Adaptive Sliding Phasor Average Control (ASPAC) instability control method has been updated for the low-emissions combustor prototype. Active combustion instability suppression using the ASPAC control method has been demonstrated experimentally with this combustor prototype in a NASA combustion test cell operating at engine pressures, temperatures, and flows. A high-frequency fuel valve was utilized to perturb the combustor fuel flow. Successful instability suppression was shown using a dynamic pressure sensor in the combustor for controller feedback. Instability control was also shown with a pressure feedback sensor in the lower temperature region upstream of the combustor. It was also demonstrated that the controller can prevent the instability from occurring while combustor operation was transitioning from a stable, low-power condition to a normally unstable high-power condition, thus enabling the high-power condition.

CO2 Emissions from Direct Energy Use of Urban Households in India.

PubMed

Ahmad, Sohail; Baiocchi, Giovanni; Creutzig, Felix

2015-10-06

India hosts the world's second largest population and offers the world's largest potential for urbanization. India's urbanization trajectory will have crucial implications on its future GHG emission levels. Using household microdata from India's 60 largest cities, this study maps GHG emissions patterns and its determinants. It also ranks the cities with respect to their household actual and "counter-factual" GHG emissions from direct energy use. We find that household GHG emissions from direct energy use correlate strongly with income and household size; population density, basic urban services (municipal water, electricity, and modern cooking-fuels access) and cultural, religious, and social factors explain more detailed emission patterns. We find that the "greenest" cities (on the basis of household GHG emissions) are Bareilly and Allahabad, while the "dirtiest" cities are Chennai and Delhi; however, when we control for socioeconomic variables, the ranking changes drastically. In the control case, we find that smaller lower-income cities emit more than expected, and larger high-income cities emit less than expected in terms of counter-factual emissions. Emissions from India's cities are similar in magnitude to China's cities but typically much lower than those of comparable U.S. cities. Our results indicate that reducing urban heat-island effects and the associated cooling degree days by greening, switching to modern nonsolid cooking fuels, and anticipatory transport infrastructure investments are key policies for the low-carbon and inclusive development of Indian cities.

Reactivity-based industrial volatile organic compounds emission inventory and its implications for ozone control strategies in China

NASA Astrophysics Data System (ADS)

Liang, Xiaoming; Chen, Xiaofang; Zhang, Jiani; Shi, Tianli; Sun, Xibo; Fan, Liya; Wang, Liming; Ye, Daiqi

2017-08-01

Increasingly serious ozone (O3) pollution, along with decreasing NOx emission, is creating a big challenge in the control of volatile organic compounds (VOCs) in China. More efficient and effective measures are assuredly needed for controlling VOCs. In this study, a reactivity-based industrial VOCs emission inventory was established in China based on the concept of ozone formation potential (OFP). Key VOCs species, major VOCs sources, and dominant regions with high reactivity were identified. Our results show that the top 15 OFP-based species, including m/p-xylene, toluene, propene, o-xylene, and ethyl benzene, contribute 69% of the total OFP but only 30% of the total emission. The architectural decoration industry, oil refinery industry, storage and transport, and seven other sources constituted the top 10 OFP subsectors, together contributing a total of 85%. The provincial and spatial characteristics of OFP are generally consistent with those of mass-based inventory. The implications for O3 control strategies in China are discussed. We propose a reactivity-based national definition of VOCs and low-reactive substitution strategies, combined with evaluations of health risks. Priority should be given to the top 15 or more species with high reactivity through their major emission sources. Reactivity-based policies should be flexibly applied for O3 mitigation based on the sensitivity of O3 formation conditions.

Using surface water application to reduce 1,3-dichloropropene emission from soil fumigation.

PubMed

Gao, Suduan; Trout, Thomas J

2006-01-01

High emissions from soil fumigants increase the risk of detrimental impact on workers, bystanders, and the environment, and jeopardize future availability of fumigants. Efficient and cost-effective approaches to minimize emissions are needed. This study evaluated the potential of surface water application (or water seal) to reduce 1,3-dichloropropene (1,3-D) emissions from soil (Hanford sandy loam) columns. Treatments included dry soil (control), initial water application (8 mm of water just before fumigant application), initial plus a second water application (2.6 mm) at 12 h, initial plus two water applications (2.6 mm each time) at 12 and 24 h, standard high density polyethylene (HDPE) tarp, initial water application plus HDPE tarp, and virtually impermeable film (VIF) tarp. Emissions from the soil surface and distribution of 1,3-D in the soil-gas phase were monitored for 2 wk. Each water application abruptly reduced 1,3-D emission flux, which rebounded over a few hours. Peak emission rates were substantially reduced, but total emission reduction was small. Total fumigant emission was 51% of applied for the control, 46% for initial water application only, and 41% for the three intermittent water applications with the remaining water treatment intermediate. The HDPE tarp alone resulted in 45% emission, while initial water application plus HDPE tarp resulted in 38% emission. The most effective soil surface treatment was VIF tarp (10% emission). Surface water application can be as effective, and less expensive than, standard HDPE tarp. Frequent water application is required to substantially reduce emissions.

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

NASA Astrophysics Data System (ADS)

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

2014-12-01

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

Review on Variable Emissivity Materials and Devices Based on Smart Chromism

NASA Astrophysics Data System (ADS)

Lang, FengPei; Wang, Hao; Zhang, ShengJun; Liu, JingBing; Yan, Hui

2018-01-01

Variable emissivity material (VEM) can dynamically vary its emissivity and infrared radiation under certain conditions, which may find potential applications in infrared stealth/camouflage, solar thermal collector, spacecraft thermal control, and smart energy-saving windows. In this paper, the variable emissivity materials and devices based on electrochromism and thermochromism are introduced. The basic principle and present status of the research in these fields are overviewed. Four kinds of representative VEMs are extensively summarized, which are tungsten trioxides (WO3), conducting polymers (CPs), perovskite oxides (A_{1-{x}}B_{{x}}MO3), and vanadium dioxide (VO2). Finally, specific issues confronted with electrochromic and thermochromic materials and devices are prospected.

Emissions of terpenoids, benzenoids, and other biogenic gas-phase organic compounds from agricultural crops and their potential implications for air quality

NASA Astrophysics Data System (ADS)

Gentner, D. R.; Ormeño, E.; Fares, S.; Ford, T. B.; Weber, R.; Park, J.-H.; Brioude, J.; Angevine, W. M.; Karlik, J. F.; Goldstein, A. H.

2014-06-01

Agriculture comprises a substantial, and increasing, fraction of land use in many regions of the world. Emissions from agricultural vegetation and other biogenic and anthropogenic sources react in the atmosphere to produce ozone and secondary organic aerosol, which comprises a substantial fraction of particulate matter (PM2.5). Using data from three measurement campaigns, we examine the magnitude and composition of reactive gas-phase organic carbon emissions from agricultural crops and their potential to impact regional air quality relative to anthropogenic emissions from motor vehicles in California's San Joaquin Valley, which is out of compliance with state and federal standards for tropospheric ozone PM2.5. Emission rates for a suite of terpenoid compounds were measured in a greenhouse for 25 representative crops from California in 2008. Ambient measurements of terpenoids and other biogenic compounds in the volatile and intermediate-volatility organic compound ranges were made in the urban area of Bakersfield and over an orange orchard in a rural area of the San Joaquin Valley during two 2010 seasons: summer and spring flowering. We combined measurements from the orchard site with ozone modeling methods to assess the net effect of the orange trees on regional ozone. When accounting for both emissions of reactive precursors and the deposition of ozone to the orchard, the orange trees are a net source of ozone in the springtime during flowering, and relatively neutral for most of the summer until the fall, when it becomes a sink. Flowering was a major emission event and caused a large increase in emissions including a suite of compounds that had not been measured in the atmosphere before. Such biogenic emission events need to be better parameterized in models as they have significant potential to impact regional air quality since emissions increase by several factors to over an order of magnitude. In regions like the San Joaquin Valley, the mass of biogenic emissions from agricultural crops during the summer (without flowering) and the potential ozone and secondary organic aerosol formation from these emissions are on the same order as anthropogenic emissions from motor vehicles and must be considered in air quality models and secondary pollution control strategies.

Aged particles derived from emissions of coal-fired power plants: The TERESA field results

PubMed Central

Kang, Choong-Min; Gupta, Tarun; Ruiz, Pablo A.; Wolfson, Jack M.; Ferguson, Stephen T.; Lawrence, Joy E.; Rohr, Annette C.; Godleski, John; Koutrakis, Petros

2013-01-01

The Toxicological Evaluation of Realistic Emissions Source Aerosols (TERESA) study was carried out at three US coal-fired power plants to investigate the potential toxicological effects of primary and photochemically aged (secondary) particles using in situ stack emissions. The exposure system designed successfully simulated chemical reactions that power plant emissions undergo in a plume during transport from the stack to receptor areas (e.g., urban areas). Test atmospheres developed for toxicological experiments included scenarios to simulate a sequence of atmospheric reactions that can occur in a plume: (1) primary emissions only; (2) H2SO4 aerosol from oxidation of SO2; (3) H2SO4 aerosol neutralized by gas-phase NH3; (4) neutralized H2SO4 with secondary organic aerosol (SOA) formed by the reaction of α-pinene with O3; and (5) three control scenarios excluding primary particles. The aged particle mass concentrations varied significantly from 43.8 to 257.1 μg/m3 with respect to scenario and power plant. The highest was found when oxidized aerosols were neutralized by gas-phase NH3 with added SOA. The mass concentration depended primarily on the ratio of SO2 to NOx (particularly NO) emissions, which was determined mainly by coal composition and emissions controls. Particulate sulfate (H2SO4 + neutralized sulfate) and organic carbon (OC) were major components of the aged particles with added SOA, whereas trace elements were present at very low concentrations. Physical and chemical properties of aged particles appear to be influenced by coal type, emissions controls and the particular atmospheric scenarios employed. PMID:20462390

The potential of exceptional climate change education on individual lifetime carbon emissions

NASA Astrophysics Data System (ADS)

Cordero, E.; Centeno, D.; Todd, A. M.

2016-12-01

Strategies to mitigate climate change often center on clean technologies such as electric vehicles and solar panels, while the mitigation potential of a quality educational experience is rarely discussed. We investigate the role of education on individual carbon emissions using case studies from an intensive one-year university general education course focused on climate science and solutions. Results from this analysis demonstrate that students who completed the university course had significantly lower carbon emissions compared to a control group. If such an educational experience could be expanded throughout the United States, we estimate that education could be as valuable a climate change mitigation method as improving the fuel efficiency of automobiles. Relatedly, we also report on a new approach to apply real-time cloud based data to track the environmental impact of students during their participation in educational climate change programs. Such a tool would help illustrate the potential of education as a viable carbon mitigation strategy.

Generating CO(2)-credits through landfill in situ aeration.

PubMed

Ritzkowski, M; Stegmann, R

2010-04-01

Landfills are some of the major anthropogenic sources of methane emissions worldwide. The installation and operation of gas extraction systems for many landfills in Europe and the US, often including technical installations for energy recovery, significantly reduced these emissions during the last decades. Residual landfill gas, however, is still continuously produced after the energy recovery became economically unattractive, thus resulting in ongoing methane emissions for many years. By landfill in situ aeration these methane emissions can be widely avoided both, during the aeration process as well as in the subsequent aftercare period. Based on model calculations and online monitoring data the amount of avoided CO(2-eq). can be determined. For an in situ aerated landfill in northern Germany, acting as a case study, 83-95% (depending on the kind and quality of top cover) of the greenhouse gas emission potential could be reduced under strictly controlled conditions. Recently the United Nations Framework Convention on Climate Change (UNFCCC) has approved a new methodology on the "Avoidance of landfill gas emissions by in situ aeration of landfills" (UNFCCC, 2009). Based on this methodology landfill aeration projects might be considered for generation of Certified Emission Reductions (CERs) in the course of CDM projects. This paper contributes towards an evaluation of the potential of landfill aeration for methane emissions reduction. Copyright 2009 Elsevier Ltd. All rights reserved.

Emission Control Technologies for Thermal Power Plants

NASA Astrophysics Data System (ADS)

Nihalani, S. A.; Mishra, Y.; Juremalani, J.

2018-03-01

Coal thermal power plants are one of the primary sources of artificial air emissions, particularly in a country like India. Ministry of Environment and Forests has proposed draft regulation for emission standards in coal-fired power plants. This includes significant reduction in sulphur-dioxide, oxides of nitrogen, particulate matter and mercury emissions. The first step is to evaluate the technologies which represent the best selection for each power plant based on its configuration, fuel properties, performance requirements, and other site-specific factors. This paper will describe various technology options including: Flue Gas Desulfurization System, Spray Dryer Absorber (SDA), Circulating Dry Scrubber (CDS), Limestone-based Wet FGD, Low NOX burners, Selective Non Catalytic Reduction, Electrostatic Precipitator, Bag House Dust Collector, all of which have been evaluated and installed extensively to reduce SO2, NOx, PM and other emissions. Each control technology has its advantages and disadvantages. For each of the technologies considered, major features, potential operating and maintenance cost impacts, as well as key factors that contribute to the selection of one technology over another are discussed here.

Enhancing the luminescence of Eu3+ /Eu2+ ion-doped hydroxyapatite by fluoridation and thermal annealing.

PubMed

Van, Hoang Nhu; Tam, Phuong Dinh; Kien, Nguyen Duc Trung; Huy, Pham Thanh; Pham, Vuong-Hung

2017-08-01

This paper reports a novel way for the synthesis of a europium (Eu)-doped fluor-hydroxyapatite (FHA) nanostructure to control the luminescence of hydroxyapatite nanophosphor, particularly, by applying optimum fluorine concentrations, annealed temperatures and pH value. The Eu-doped FHA was made using the co-precipitation method followed by thermal annealing in air and reducing in a H 2 atmosphere to control the visible light emission center of the nanophosphors. The intensities of the OH - group decreased with the increasing fluorine concentrations. For the specimens annealed in air, the light emission center of the nanophosphor was 615 nm, which was emission from the Eu 3 + ion. However, when they were annealed in reduced gas (Ar + 5% H 2 ), a 448 nm light emission center from the Eu 2 + ion of FHA was observed. The presence of fluorine in Eu-doped FHA resulted in a significant enhancement of nanophosphor luminescence, which has potential application in light emission and nanomedicine. Copyright © 2016 John Wiley & Sons, Ltd.

Soil greenhouse gas emissions and carbon budgeting in a short-hydroperiod floodplain wetland

NASA Astrophysics Data System (ADS)

Batson, Jackie; Noe, Gregory B.; Hupp, Cliff R.; Krauss, Ken W.; Rybicki, Nancy B.; Schenk, Edward R.

2015-01-01

Understanding the controls on floodplain carbon (C) cycling is important for assessing greenhouse gas emissions and the potential for C sequestration in river-floodplain ecosystems. We hypothesized that greater hydrologic connectivity would increase C inputs to floodplains that would not only stimulate soil C gas emissions but also sequester more C in soils. In an urban Piedmont river (151 km2 watershed) with a floodplain that is dry most of the year, we quantified soil CO2, CH4, and N2O net emissions along gradients of floodplain hydrologic connectivity, identified controls on soil aerobic and anaerobic respiration, and developed a floodplain soil C budget. Sites were chosen along a longitudinal river gradient and across lateral floodplain geomorphic units (levee, backswamp, and toe slope). CO2 emissions decreased downstream in backswamps and toe slopes and were high on the levees. CH4 and N2O fluxes were near zero; however, CH4 emissions were highest in the backswamp. Annual CO2 emissions correlated negatively with soil water-filled pore space and positively with variables related to drier, coarser soil. Conversely, annual CH4 emissions had the opposite pattern of CO2. Spatial variation in aerobic and anaerobic respiration was thus controlled by oxygen availability but was not related to C inputs from sedimentation or vegetation. The annual mean soil CO2 emission rate was 1091 g C m-2 yr-1, the net sedimentation rate was 111 g C m-2 yr-1, and the vegetation production rate was 240 g C m-2 yr-1, with a soil C balance (loss) of -338 g C m-2 yr-1. This floodplain is losing C likely due to long-term drying from watershed urbanization.

Air pollutant emissions from Chinese households: A major and underappreciated ambient pollution source.

PubMed

Liu, Jun; Mauzerall, Denise L; Chen, Qi; Zhang, Qiang; Song, Yu; Peng, Wei; Klimont, Zbigniew; Qiu, Xinghua; Zhang, Shiqiu; Hu, Min; Lin, Weili; Smith, Kirk R; Zhu, Tong

2016-07-12

As part of the 12th Five-Year Plan, the Chinese government has developed air pollution prevention and control plans for key regions with a focus on the power, transport, and industrial sectors. Here, we investigate the contribution of residential emissions to regional air pollution in highly polluted eastern China during the heating season, and find that dramatic improvements in air quality would also result from reduction in residential emissions. We use the Weather Research and Forecasting model coupled with Chemistry to evaluate potential residential emission controls in Beijing and in the Beijing, Tianjin, and Hebei (BTH) region. In January and February 2010, relative to the base case, eliminating residential emissions in Beijing reduced daily average surface PM2.5 (particulate mater with aerodynamic diameter equal or smaller than 2.5 micrometer) concentrations by 14 ± 7 μg⋅m(-3) (22 ± 6% of a baseline concentration of 67 ± 41 μg⋅m(-3); mean ± SD). Eliminating residential emissions in the BTH region reduced concentrations by 28 ± 19 μg⋅m(-3) (40 ± 9% of 67 ± 41 μg⋅m(-3)), 44 ± 27 μg⋅m(-3) (43 ± 10% of 99 ± 54 μg⋅m(-3)), and 25 ± 14 μg⋅m(-3) (35 ± 8% of 70 ± 35 μg⋅m(-3)) in Beijing, Tianjin, and Hebei provinces, respectively. Annually, elimination of residential sources in the BTH region reduced emissions of primary PM2.5 by 32%, compared with 5%, 6%, and 58% achieved by eliminating emissions from the transportation, power, and industry sectors, respectively. We also find air quality in Beijing would benefit substantially from reductions in residential emissions from regional controls in Tianjin and Hebei, indicating the value of policies at the regional level.

Economic growth and carbon emission control

NASA Astrophysics Data System (ADS)

Zhang, Zhenyu

The question about whether environmental improvement is compatible with continued economic growth remains unclear and requires further study in a specific context. This study intends to provide insight on the potential for carbon emissions control in the absence of international agreement, and connect the empirical analysis with theoretical framework. The Chinese electricity generation sector is used as a case study to demonstrate the problem. Both social planner and private problems are examined to derive the conditions that define the optimal level of production and pollution. The private problem will be demonstrated under the emission regulation using an emission tax, an input tax and an abatement subsidy respectively. The social optimal emission flow is imposed into the private problem. To provide tractable analytical results, a Cobb-Douglas type production function is used to describe the joint production process of the desired output and undesired output (i.e., electricity and emissions). A modified Hamiltonian approach is employed to solve the system and the steady state solutions are examined for policy implications. The theoretical analysis suggests that the ratio of emissions to desired output (refer to 'emission factor'), is a function of productive capital and other parameters. The finding of non-constant emission factor shows that reducing emissions without further cutting back the production of desired outputs is feasible under some circumstances. Rather than an ad hoc specification, the optimal conditions derived from our theoretical framework are used to examine the relationship between desired output and emission level. Data comes from the China Statistical Yearbook and China Electric Power Yearbook and provincial information of electricity generation for the year of 1993-2003 are used to estimate the Cobb-Douglas type joint production by the full information maximum likelihood (FIML) method. The empirical analysis shed light on the optimal policies of emissions control required for achieving the social goal in a private context. The results suggest that the efficiency of abatement technology is crucial for the timing of executing the emission tax. And emission tax is preferred to an input tax, as long as the detection of emissions is not costly and abatement technology is efficient. Keywords: Economic growth, Carbon emission, Power generation, Joint production, China

Acid emissions monitoring needs in ceramic tile industry: challenges derived from new policy trends

NASA Astrophysics Data System (ADS)

Celades, Irina; Gomar, Salvador; Romero, Fernando; Chauhan, Amisha; Delpech, Bertrand; Jouhara, Hussam

2017-11-01

The emission of acid compounds during the manufacture of ceramic tiles is strongly related to the presence of precursors in the raw materials and/or fuels used, with some exceptions such as the production of thermal NOX. The stages with the potential to produce significant emissions of these compounds have been identified as the suspension spray drying and tile firing stages. The monitoring of emission levels of acid pollutants in these stages has turned in a great importance issue from a regulatory and industrial aspect. The DREAM project (https://www.spire2030.eu/dream) will tackle the regulation of acidic emissions focusing in the firing stage. The initial stages of the project have made it possible to identify the design requirements for the monitoring system. This will allow the control of acid pollutants emissions and other key parameters such as pressure, flow, temperature and humidity. One of the tasks developed has been the review and compilation of current emissions monitoring systems detailing technical specifications such as: position (in situ or extractive), measurement principle and frequency. The future policy trends in air pollution are encouraging the continuous monitoring across the European industry. The present document assesses the advantages regarding environmental impact control, highlighting the main challenges for the ceramic tile industry.

A case study of development and application of a streamlined control and response modeling system for PM2.5 attainment assessment in China.

PubMed

Long, Shicheng; Zhu, Yun; Jang, Carey; Lin, Che-Jen; Wang, Shuxiao; Zhao, Bin; Gao, Jian; Deng, Shuang; Xie, Junping; Qiu, Xuezhen

2016-03-01

This article describes the development and application of a streamlined air control and response modeling system with a novel response surface modeling-linear coupled fitting method and a new module to provide streamlined model data for PM2.5 attainment assessment in China. This method is capable of significantly reducing the dimensions required to establish a response surface model, as well as capturing more realistic response of PM2.5 to emission changes with a limited number of model simulations. The newly developed module establishes a data link between the system and the Software for Model Attainment Test-Community Edition (SMAT-CE), and has the ability to rapidly provide model responses to emission control scenarios for SMAT-CE using a simple interface. The performance of this streamlined system is demonstrated through a case study of the Yangtze River Delta (YRD) in China. Our results show that this system is capable of reproducing the Community Multi-Scale Air Quality (CMAQ) model simulation results with maximum mean normalized error<3.5%. It is also demonstrated that primary emissions make a major contribution to ambient levels of PM2.5 in January and August (e.g., more than 50% contributed by primary emissions in Shanghai), and Shanghai needs to have regional emission control both locally and in its neighboring provinces to meet China's annual PM2.5 National Ambient Air Quality Standard. The streamlined system provides a real-time control/response assessment to identify the contributions of major emission sources to ambient PM2.5 (and potentially O3 as well) and streamline air quality data for SMAT-CE to perform attainment assessments. Copyright © 2015. Published by Elsevier B.V.

Reduced binding potential of GABA-A/benzodiazepine receptors in individuals at ultra-high risk for psychosis: an [18F]-fluoroflumazenil positron emission tomography study.

PubMed

Kang, Jee In; Park, Hae-Jeong; Kim, Se Joo; Kim, Kyung Ran; Lee, Su Young; Lee, Eun; An, Suk Kyoon; Kwon, Jun Soo; Lee, Jong Doo

2014-05-01

Altered transmission of gamma-aminobutyric acid (GABA), a major inhibitory neurotransmitter, may contribute to the development of schizophrenia. The purpose of the present study was to investigate the presence of GABA-A/benzodiazepine (BZ) receptor binding abnormalities in individuals at ultra-high risk (UHR) for psychosis in comparison with normal controls using [(18)F]-fluoroflumazenil (FFMZ) positron emission tomography (PET). In particular, we set regions of interest in the striatum (caudate, putamen, and nucleus accumbens) and medial temporal area (hippocampus and parahippocampal gyrus). Eleven BZ-naive people at UHR and 15 normal controls underwent PET scanning using [(18)F]-FFMZ to measure GABA-A/BZ receptor binding potential. The regional group differences between UHR individuals and normal controls were analyzed using Statistical Parametric Mapping 8 software. Participants were evaluated using the structured interview for prodromal syndromes and neurocognitive function tasks. People at UHR demonstrated significantly reduced binding potential of GABA-A/BZ receptors in the right caudate. Altered GABAergic transmission and/or the imbalance of inhibitory and excitatory systems in the striatum may be present at the putative prodromal stage and play a pivotal role in the pathophysiology of psychosis.

Investigation of fugitive dust emissions from nepheline syenite mine tailings near Nephton, Ontario

NASA Astrophysics Data System (ADS)

Ogungbemide, Damilare Immanuel

A set of experiments was designed to investigate the factors--atmospheric and surficial--controlling fugitive dust emissions from the tailings ponds of UNIMIN Canada, a mining company that extracts and produces nepheline syenite (feldspar) at two adjacent sites (Nephton and Blue Mountain) located north of Havelock, Ontario. Using wind tunnel measurements, the combined influence of relative humidity and temperature (represented by the absolute matric potential, |psi|) on dust emission was quantified and modeled. About 300 experimental runs were conducted under various conditions of wind speed (4.5-6.25 ms -1), temperature (0-30°C) and relative humidity (10-70%). Generally, dust flux decreased as a logarithmic function of matric potential, with dust emission strongly suppressed for RH > 60% or |psi|<70 MPa. Field measurements also confirmed the role of relative humidity in suppressing dust emission. Irrigation, which is widely used by mines to control dust emissions, reduced ambient dust concentration at the study site only about 60% of the time, with the highest mitigation efficiencies (average of 90%) occurring when the total depth of water applied intermittently over a few hours was greater than 10 mm. In the absence of emergent vegetation, the terrestrial laser scanning (TLS) technique proved to be a promising method for detecting and estimating both spatial and temporal moisture content changes in the field environment, particularly for the very thin surface layer, which is the most important layer for dust emission. It is hoped that the results from this study will help mines to optimize their dust management programs for the range of climate and topographic conditions found at their sites, and also serve as a source of useful information and input data for atmospheric dispersion models, such as AERMOD and CALPUFF, whose accuracy depends on the quality of the input data such as the emission rate.

Emission of greenhouse gases from controlled incineration of cattle manure.

PubMed

Oshita, Kazuyuki; Sun, Xiucui; Taniguchi, Miki; Takaoka, Masaki; Matsukawa, Kazutsugu; Fujiwara, Taku

2012-01-01

Greenhouse gas emission is a potential limiting factor in livestock farming development. While incineration is one approach to minimize livestock manure, there are concerns about significant levels of nitrogen and organic compounds in manure as potential sources of greenhouse gas emissions (N2O and CH4). In this study, the effects of various incineration conditions, such as the furnace temperature and air ratio on N2O and CH4 formation behaviour, of cattle manure (as a representative livestock manure) were investigated in a pilot rotary kiln furnace. The results revealed that N2O emissions decreased with increasing temperature and decreasing air ratio. In addition, CH4 emissions tended to be high above 800 degrees C at a low air ratio. The emission factors for N2O and CH4 under the general conditions (combustion temperature of 800-850 degrees C and air ratio of 1.4) were determined to be 1.9-6.0% g-N2O-N/g-N and 0.0046-0.26% g-CH4/g-burning object, respectively. The emission factor for CH4 differed slightly from the published values between 0.16 and 0.38% g-CH4/g-burning object. However, the emission factor for N2O was much higher than the currently accepted value of 0.7% g-N2O-N/g-N and, therefore, it is necessary to revise the N2O emission factor for the incineration of livestock manure.

Temporal variation of aerobic methane oxidation over a tidal cycle in a wetland of northern Taiwan.

NASA Astrophysics Data System (ADS)

Lee, T. Y.; Wang, P. L.; Lin, L. H.

2017-12-01

Aerobic methanotrophy plays an important role in controlling methane emitted from wetlands. However, the activity of aerobic methanotrophy regulated by temporal fluctuation of oxygen and methane supply in tidal wetlands is not well known. This study aims to examine the dynamics of methane fluxes and potential aerobic methane consumption rates in a tidal wetland of northern Taiwan, where the variation of environmental characteristics, such as sulfate and methane concentration in pore water has been demonstrated during a tidal cycle. Two field campaigns were carried out in December of 2016 and March of 2017. Fluxes of methane emission, methane concentrations in surface sediments and oxygen profiles were measured at different tidal phases. Besides, batch incubations were conducted on surface sediments in order to quantify potential microbial methane consumption rates and to derive the kinetic parameters for aerobic methanotrophy. Our results demonstrated temporal changes of the surface methane concentration and the methane emission flux during a tidal cycle, while the oxygen flux into the sediment was kept at a similar magnitude. The methane flux was low when the surface was exposed for both shortest and longest periods of time. The potential aerobic methane oxidation rate was high for sample collected from the surface sediments exposed the longest. No correlation could be found between the potential aerobic methane oxidation rate and either the oxygen downward flux or methane emission flux. The decoupled relationships between these observed rates and fluxes suggest that, rather than aerobic methanotrophy, heterotrophic respirations exert a profound control on oxygen flux, and the methane emission is not only been affected by methane consumption but also methane production at depths. The maximum potential rate and the half saturation concentration determined from the batch incubations were high for the surface sediments collected in low tide, suggesting that aerobic methanotrophy could be modulated to reach peak activity once the influence of saline water is reduced to a low level.

Developing Shipping Emissions Assessments, Inventories and Scenarios (Invited)

NASA Astrophysics Data System (ADS)

Corbett, J. J.

2010-12-01

Inventories of shipping have been important contributions to scientific understanding of regional pollution and transboundary transport. These inventories have also been used to evaluate global scale environmental and climate effects and trends. However, these inventories also inform policy making decisions and this role is increasingly occurring within the timescale of scientific assessment. Shipping exhibits a growth trend for uncontrolled pollutants that is highly coupled to economic activity, and historically increasing faster than many other anthropogenic sources on a global and regional scale. Shipping emissions are being regulated asymmetrically in various dimensions. Some pollutants are being controlled more than others, some regions are subject to stricter controls, and correlated changes in operations are affecting unregulated pollutant emissions. Shipping inventories require more than current assessments, including historic and future scenarios. Generally conceived as sets of business-as-usual (BAU) and high-growth scenarios, ship inventories now also need regulatory control pathways and maximum feasible reduction (MFR) scenarios. In this context, shipping inventories also present other challenges to both scientists and policymakers. Systemic bias can occur in non-shipping assessments when emissions along well-traveled shipping lanes are ignored by far offshore scientific studies, even some campaigns that control very carefully the potential influence of the shipping platforms for their measurements. Examples where shipping may contribute understood and potential biases include: a. Health impacts from transboundary pollution b. Ozone trends over the Pacific c. Sulfur emissions from biogenic sources in Northern hemisphere d. Acidification of coastal waters (potential) e. Arctic impacts on snow and ice Other challenges exist. The fuels and technology used by ships are unique from other transportation, from other stationary sources - and these are changing with economic and regulatory influences differently from other sources. The shifting stock of vessels from new-builds serving primary markets in one region to aging vessel technologies serving secondary markets produces substantial differences in future activity projections. This is compounded by the emissions differences between vessels on liner schedules and ships with similar technologies operating on charter or spot-market bases. Different rates of change drive growth among vessel types differently, so regional pattern shifts will occur, and need to be forecast or depicted in scenarios. Regulatory pathways are emerging with less clarity, but affect regional marine inputs. Scientists who measure emissions need to engage engineering principles of combustion, economics principles of supply and demand, and policy inputs to produce inventories that are more coherent, and more useful to the emerging purposes. Moreover, advanced studies (e.g., inverse modeling, source attribution, and control scenario validation) require design of “closure experiments”, where modeling of inventory measurements and modeled ambient impacts is corroborated and reconciled with field stack measurements and field observation campaigns. The most recent shipping inventories and scenarios are now providing details that recognize and address these issues.

Economic Savings from Using Economic Incentives for Environmental Pollution Control (1999)

EPA Pesticide Factsheets

Economic incentives, such as emission taxes, effluent trading, deposit refund systems, information reporting requirements, liability for harm caused by pollution, and voluntary programs have the potential to achieve environmental objectives at lower cost.

Model assessment of atmospheric pollution control schemes for critical emission regions

NASA Astrophysics Data System (ADS)

Zhai, Shixian; An, Xingqin; Liu, Zhao; Sun, Zhaobin; Hou, Qing

2016-01-01

In recent years, the atmospheric environment in portions of China has become significantly degraded and the need for emission controls has become urgent. Because more international events are being planned, it is important to implement air quality assurance targeted at significant events held over specific periods of time. This study sets Yanqihu (YQH), Beijing, the location of the 2014 Beijing APEC (Asia-Pacific Economic Cooperation) summit, as the target region. By using the atmospheric inversion model FLEXPART, we determined the sensitive source zones that had the greatest impact on the air quality of the YQH region in November 2012. We then used the air-quality model Models-3/CMAQ and a high-resolution emissions inventory of the Beijing-Tianjian-Hebei region to establish emission reduction tests for the entire source area and for specific sensitive source zones. This was achieved by initiating emission reduction schemes at different ratios and different times. The results showed that initiating a moderate reduction of emissions days prior to a potential event is more beneficial to the air quality of Beijing than initiating a high-strength reduction campaign on the day of the event. The sensitive source zone of Beijing (BJ-Sens) accounts for 54.2% of the total source area of Beijing (BJ), but its reduction effect reaches 89%-100% of the total area, with a reduction efficiency 1.6-1.9 times greater than that of the entire area. The sensitive source zone of Huabei (HuaB-Sens.) only represents 17.6% of the total area of Huabei (HuaB), but its emission reduction effect reaches 59%-97% of the entire area, with a reduction efficiency 4.2-5.5 times greater than that of the total area. The earlier that emission reduction measures are implemented, the greater the effect they have on preventing the transmission of pollutants. In addition, expanding the controlling areas to sensitive provinces and cities around Beijing (HuaB-sens) can significantly accelerate the reduction effects compared to controlling measures only in the Beijing sensitive source zone (BJ-Sens). Therefore, when enacting emission reduction schemes, cooperating with surrounding provinces and cities, as well as narrowing the reduction scope to specific sensitive source zones prior to unfavorable meteorological conditions, can help reduce emissions control costs and improve the efficiency and maneuverability of emission reduction schemes.

Methane and CO2 emissions from China's hydroelectric reservoirs: a new quantitative synthesis.

PubMed

Li, Siyue; Zhang, Quanfa; Bush, Richard T; Sullivan, Leigh A

2015-04-01

Controversy surrounds the green credentials of hydroelectricity because of the potentially large emission of greenhouse gases (GHG) from associated reservoirs. However, limited and patchy data particularly for China is constraining the current global assessment of GHG releases from hydroelectric reservoirs. This study provides the first evaluation of the CO2 and CH4 emissions from China's hydroelectric reservoirs by considering the reservoir water surface and drawdown areas, and downstream sources (including spillways and turbines, as well as river downstream). The total emission of 29.6 Tg CO2/year and 0.47 Tg CH4/year from hydroelectric reservoirs in China, expressed as CO2 equivalents (eq), corresponds to 45.6 Tg CO2eq/year, which is 2-fold higher than the current GHG emission (ca. 23 Tg CO2eq/year) from global temperate hydropower reservoirs. China's average emission of 70 g CO2eq/kWh from hydropower amounts to 7% of the emissions from coal-fired plant alternatives. China's hydroelectric reservoirs thus currently mitigate GHG emission when compared to the main alternative source of electricity with potentially far great reductions in GHG emissions and benefits possible through relatively minor changes to reservoir management and design. On average, the sum of drawdown and downstream emission including river reaches below dams and turbines, which is overlooked by most studies, represents the equivalent of 42% of the CO2 and 92% of CH4 that emit from hydroelectric reservoirs in China. Main drivers on GHG emission rates are summarized and highlight that water depth and stratification control CH4 flux, and CO2 flux shows significant negative relationships with pH, DO, and Chl-a. Based on our finding, a substantial revision of the global carbon emissions from hydroelectric reservoirs is warranted.

Real-world emissions of in-use off-road vehicles in Mexico.

PubMed

Zavala, Miguel; Huertas, Jose Ignacio; Prato, Daniel; Jazcilevich, Aron; Aguilar, Andrés; Balam, Marco; Misra, Chandan; Molina, Luisa T

2017-09-01

Off-road vehicles used in construction and agricultural activities can contribute substantially to emissions of gaseous pollutants and can be a major source of submicrometer carbonaceous particles in many parts of the world. However, there have been relatively few efforts in quantifying the emission factors (EFs) and for estimating the potential emission reduction benefits using emission control technologies for these vehicles. This study characterized the black carbon (BC) component of particulate matter and NOx, CO, and CO 2 EFs of selected diesel-powered off-road mobile sources in Mexico under real-world operating conditions using on-board portable emissions measurements systems (PEMS). The vehicles sampled included two backhoes, one tractor, a crane, an excavator, two front loaders, two bulldozers, an air compressor, and a power generator used in the construction and agricultural activities. For a selected number of these vehicles the emissions were further characterized with wall-flow diesel particle filters (DPFs) and partial-flow DPFs (p-DPFs) installed. Fuel-based EFs presented less variability than time-based emission rates, particularly for the BC. Average baseline EFs in working conditions for BC, NOx, and CO ranged from 0.04 to 5.7, from 12.6 to 81.8, and from 7.9 to 285.7 g/kg-fuel, respectively, and a high dependency by operation mode and by vehicle type was observed. Measurement-base frequency distributions of EFs by operation mode are proposed as an alternative method for characterizing the variability of off-road vehicles emissions under real-world conditions. Mass-based reductions for black carbon EFs were substantially large (above 99%) when DPFs were installed and the vehicles were idling, and the reductions were moderate (in the 20-60% range) for p-DPFs in working operating conditions. The observed high variability in measured EFs also indicates the need for detailed vehicle operation data for accurately estimating emissions from off-road vehicles in emissions inventories. Measurements of off-road vehicles used in construction and agricultural activities in Mexico using on-board portable emissions measurements systems (PEMS) showed that these vehicles can be major sources of black carbon and NO X . Emission factors varied significantly under real-world operating conditions, suggesting the need for detailed vehicle operation data for accurately estimating emissions inventories. Tests conducted in a selected number of sampled vehicles indicated that diesel particle filters (DPFs) are an effective technology for control of diesel particulate emissions and can provide potentially large emissions reduction in Mexico if widely implemented.

Nature of air pollution, emission sources, and management in the Indian cities

NASA Astrophysics Data System (ADS)

Guttikunda, Sarath K.; Goel, Rahul; Pant, Pallavi

2014-10-01

The global burden of disease study estimated 695,000 premature deaths in 2010 due to continued exposure to outdoor particulate matter and ozone pollution for India. By 2030, the expected growth in many of the sectors (industries, residential, transportation, power generation, and construction) will result in an increase in pollution related health impacts for most cities. The available information on urban air pollution, their sources, and the potential of various interventions to control pollution, should help us propose a cleaner path to 2030. In this paper, we present an overview of the emission sources and control options for better air quality in Indian cities, with a particular focus on interventions like urban public transportation facilities; travel demand management; emission regulations for power plants; clean technology for brick kilns; management of road dust; and waste management to control open waste burning. Also included is a broader discussion on key institutional measures, like public awareness and scientific studies, necessary for building an effective air quality management plan in Indian cities.

Environmental control implications of generating electric power from coal. 1977 technology status report. Appendix D. Assessment of NO/sub x/ control technology for coal fired utility boilers. [Low-excess-air, staged combustion, flu gas recirculation and burner design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1977-12-01

An NOx control technology assessment study was conducted to examine the effectiveness of low-excess-air firing, staged combustion, flue gas recirculation, and current burner/boiler designs as applied to coal-fired utility boilers. Significant variations in NOx emissions exist with boiler type, firing method, and coal type, but a relative comparison of emissions control performance, cost, and operational considerations is presented for each method. The study emphasized the numerous operational factors that are of major importance to the user in selecting and implementing a combustion modification technique. Staged combustion and low-excess-air operation were identified as the most cost-effective methods for existing units. Closemore » control of local air/fuel ratios and rigorous combustion equipment maintenance are essential to the success of both methods. Flue gas recirculation is relatively ineffective and has the added concern of tube erosion. More research is needed to resolve potential corrosion concerns with low-NOx operating modes. Low-NOx burners in conjunction with a compartmentalized windbox are capable of meeting a 0.6-lb/million Btu emission level on new units. Advanced burner designs are being developed to meet research emission goals of approximately 0.25 lb/MBtu.« less

Rice emissions during field flooding and air pollution feedbacks across South Korea

NASA Astrophysics Data System (ADS)

So, C.; Diskin, G. S.; DiGangi, J. P.; Choi, Y.; Rana, M.; Hughes, S.; Blake, D. R.; Nault, B.; Schroeder, J.; Campuzano Jost, P.; Jimenez, J. L.; Kim, M. J.; Teng, A.; Crounse, J. D.; Wenneberg, P.; Kaser, L.; Mikoviny, T.; Müller, M.; Wisthaler, A.; Pusede, S. E.

2017-12-01

Nitrous oxide (N2O) and methane (CH4) are important long-lived greenhouse gases. Known anthropogenic sources of these gases include rice cultivation, which represents anywhere between 5% and 20% of methane emissions globally. Other volatile molecules are also produced by soil biogeochemistry when rice fields are flooded, including small organic oxygenates. Here, we use recent aircraft measurements from the KORUS-AQ experiment to describe controls over rice emissions of N2O and CH4 at regional-scales across the South Korean Peninsula. We also investigate potential emissions of molecular hydrogen and volatile alcohols and organic acids and consider the effect of aerosol nitrate and sulfate deposition on rice soil biogeochemistry on paddies downwind of polluted urban areas.

Regulation of the Rhythmic Emission of Plant Volatiles by the Circadian Clock.

PubMed

Zeng, Lanting; Wang, Xiaoqin; Kang, Ming; Dong, Fang; Yang, Ziyin

2017-11-13

Like other organisms, plants have endogenous biological clocks that enable them to organize their metabolic, physiological, and developmental processes. The representative biological clock is the circadian system that regulates daily (24-h) rhythms. Circadian-regulated changes in growth have been observed in numerous plants. Evidence from many recent studies indicates that the circadian clock regulates a multitude of factors that affect plant metabolites, especially emitted volatiles that have important ecological functions. Here, we review recent progress in research on plant volatiles showing rhythmic emission under the regulation of the circadian clock, and on how the circadian clock controls the rhythmic emission of plant volatiles. We also discuss the potential impact of other factors on the circadian rhythmic emission of plant volatiles.

Mobile environment for an emission spectrometer

NASA Astrophysics Data System (ADS)

Radziak, Kamil; Litwin, Dariusz; Galas, Jacek; Tyburska-Staniewska, Anna; Ramsza, Andrzej

2017-08-01

The paper describes a mobile application to be used in a chemical analytical laboratory. The program running under the control of Android operating system allows for preview of measurements recorded by the emission spectrometer. Another part of the application monitors operational and configuration parameters of the device in real time. The first part of this paper includes an overview of the atomic spectrometry. The second part contains a description of the application and its further potential development direction.

Dual fluorescence of excited state intra-molecular proton transfer of HBFO: mechanistic understanding, substituent and solvent effects.

PubMed

Yang, Wenjing; Chen, Xuebo

2014-03-07

A combined approach of the multiconfigurational perturbation theory with the Rice-Ramsperger-Kassel-Marcus methodology has been employed to calculate the minimum potential energy profiles and the rates of excited state intra-molecular proton transfer (ESIPT) for the WOLED material molecule of HBFO and its four meta- or para-substituted compounds in gas phase, acetonitrile and cyclohexane solvents. The kinetic control for these reactions is quantitatively determined and extensively studied on the basis of the accurate potential energy surfaces when the thermodynamic factor associated with the free energy change becomes negligible in the case of the existence of a significant barrier in the ESIPT process. These computational efforts contribute to a deep understanding of the ESIPT mechanism, dual emission characteristics, kinetic controlling factor, substituent and solvent effects for these material molecules. The white light emission is generated by the establishment of dynamic equilibrium between enol and keto forms in the charge transfer excited SCT((1)ππ*) state. The performance of white light emission is quantitatively demonstrated to be mainly sensitive to the molecular tailoring approach of the electronic properties of meta- or para- substituents by the modulation of the forward/backward ESIPT rate ratio. The quality of white light emission is slightly tunable through its surrounding solvent environment. These computational results will provide a useful strategy for the molecular design of OLED and WOLED materials.

Occupational exposure to lead and lung cancer: results from two case-control studies in Montreal, Canada.

PubMed

Wynant, Willy; Siemiatycki, Jack; Parent, Marie-Élise; Rousseau, Marie-Claude

2013-03-01

We investigated the association between workplace lead exposure and lung cancer risk, separately for organic lead and for inorganic lead, from either engine emissions or from other sources. Two population-based case-control studies were carried out in Montreal (1979-1986 and 1996-2002) to investigate occupational factors in relation to lung cancer among 1593 men with histologically confirmed incident lung cancer, and 1426 controls from the general population. Interviews elicited information on sociodemographic characteristics, lifetime smoking and occupational history. Chemists translated each job into potential chemical exposures. Cumulative indices of exposure were derived and classified into non-substantial and substantial exposure. ORs adjusted for several potential confounders including smoking, and 95% CIs were estimated by logistic regression. Lifetime prevalences of exposure in Study I were 3% for organic lead, 40% for inorganic lead from engine emissions and 17% for inorganic lead from other sources; corresponding prevalences in Study II were 4%, 19% and 16%, respectively. No associations were observed when comparing ever to never exposed subjects in pooled analyses (organic lead, OR=1.39, 95% CI 0.77 to 2.52; inorganic lead from engine emissions: OR=0.89, 95% CI 0.72 to 1.09; inorganic lead from other sources: OR=0.99, 95% CI 0.76 to 1.29). Nor were these exposures associated with lung cancer in subjects with substantial cumulative exposure. In this large study, using a blinded expert-based assessment of lifetime occupational exposure and adjustment for several potential confounders, we observed no increased risk of lung cancer with exposure to lead compounds.

Global Air Quality and Climate Impacts of Mitigating Short-lived Climate Pollution in China

NASA Astrophysics Data System (ADS)

Harper, K.; Unger, N.; Heyes, C.; Kiesewetter, G.; Klimont, Z.; Schoepp, W.; Wagner, F.

2014-12-01

China is a major emitter of harmful air pollutants, including the short-lived climate pollutants (SLCPs) and their precursors. Implementation of pollution control technologies provides a mechanism for simultaneously protecting human and ecosystem health and achieving near-term climate co-benefits; however, predicting the outcomes of technical and policy interventions is challenging because the SLCPs participate in both climate warming and cooling and share many common emission sources. Here, we present the results of a combined regional integrated assessment and global climate modeling study aimed at quantifying the near-term climate and air quality co-benefits of selective control of Chinese air pollution emissions. Results from IIASA's Greenhouse Gas - Air Pollution Interactions and Synergies (GAINS) integrated assessment model indicate that methane emission reductions make up > 75% of possible CO2-equivalent emission reductions of the SLCPs and their precursors in China in 2030. A multi-pollutant emission reduction scenario incorporating the 2030 Chinese pollution control measures with the highest potential for future climate impact is applied to the NASA ModelE2 - Yale Interactive Terrestrial Biosphere (NASA ModelE2-YIBs) global carbon - chemistry - climate model to assess the regional and long-range impacts of Chinese SLCP mitigation measures. Using model simulations that incorporate dynamic methane emissions and photosynthesis-dependent isoprene emissions, we quantify the impacts of Chinese reductions of the short-lived air pollutants on radiative forcing and on surface ozone and particulate air pollution. Present-day modeled methane mole fractions are evaluated against SCIAMACHY methane columns and NOAA ESRL/GMD surface flask measurements.

New potentials for conventional aircraft when powered by hydrogen-enriched gasoline

NASA Technical Reports Server (NTRS)

Menard, W. A.; Moynihan, P. I.; Rupe, J. H.

1976-01-01

Hydrogen enrichment for aircraft piston engines is under study in a new NASA program. The objective of the program is to determine the feasibility of inflight injection of hydrogen in general aviation aircraft engines to reduce fuel consumption and to lower emission levels. A catalytic hydrogen generator will be incorporated as part of the air induction system of a Lycoming turbocharged engine and will generate hydrogen by breaking down small amounts of the aviation gasoline used in the normal propulsion system. This hydrogen will then be mixed with gasoline and compressed air from the turbocharger before entering the engine combustion chamber. The paper summarizes the results of a systems analysis study. Calculations assuming a Beech Duke aircraft indicate that fuel savings on the order of 20% are possible. An estimate of the potential for the utilization of hydrogen enrichment to control exhaust emissions indicates that it may be possible to meet the 1979 Federal emission standards.

Co-Optimization of Internal Combustion Engines and Biofuels

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCormick, Robert L.

2016-03-08

The development of advanced engines has significant potential advantages in reduced aftertreatment costs for air pollutant emission control, and just as importantly for efficiency improvements and associated greenhouse gas emission reductions. There are significant opportunities to leverage fuel properties to create more optimal engine designs for both advanced spark-ignition and compression-ignition combustion strategies. The fact that biofuel blendstocks offer a potentially low-carbon approach to fuel production, leads to the idea of optimizing the entire fuel production-utilization value chain as a system from the standpoint of life cycle greenhouse gas emissions. This is a difficult challenge that has yet to bemore » realized. This presentation will discuss the relationship between chemical structure and critical fuel properties for more efficient combustion, survey the properties of a range of biofuels that may be produced in the future, and describe the ongoing challenges of fuel-engine co-optimization.« less

Is obesity associated with global warming?

PubMed

Squalli, J

2014-12-01

Obesity is a national epidemic that imposes direct medical and indirect economic costs on society. Recent scholarly inquiries contend that obesity also contributes to global warming. The paper investigates the relationship between greenhouse gas emissions and obesity. Cross-sectional state-level data for the year 2010. Multiple regression analysis using least squares with bootstrapped standard errors and quantile regression. States with higher rates of obesity are associated with higher CO2 and CH4 emissions (p < 0.05) and marginally associated with higher N2O emissions (p < 0.10), net of other factors. Reverting to the obesity rates of the year 2000 across the entire United States could decrease greenhouse gas emissions by about two percent, representing more than 136 million metric tons of CO2 equivalent. Future studies should establish clear causality between obesity and emissions by using longitudinal data while controlling for other relevant factors. They should also consider identifying means to net out the potential effects of carbon sinks, conversion of CH4 to energy, cross-state diversion, disposal, and transfer of municipal solid waste, and potentially lower energy consumption from increased sedentariness. Copyright © 2014 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

CO{sub 2} Emission Calculations and Trends

DOE R&D Accomplishments Database

Boden, T. A.; Marland, G.; Andres, R. J.

1995-06-01

Evidence that the atmospheric CO{sub 2}concentration has risen during the past several decades is irrefutable. Most of the observed increase in atmospheric CO{sub 2} is believed to result from CO{sub 2} releases from fossil-fuel burning. The United Nations (UN) Framework Convention on Climate Change (FCCC), signed in Rio de Janeiro in June 1992, reflects global concern over the increasing CO{sub 2} concentration and its potential impact on climate. One of the convention`s stated objectives was the stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. Specifically, the FCCC asked all 154 signing countries to conduct an inventory of their current greenhouse gas emissions, and it set nonbinding targets for some countries to control emissions by stabilizing them at 1990 levels by the year 2000. Given the importance of CO{sub 2} as a greenhouse gas, the relationship between CO{sub 2} emissions and increases in atmospheric CO{sub 2} levels, and the potential impacts of a greenhouse gas-induced climate change; it is important that comprehensive CO{sub 2} emissions records be compiled, maintained, updated, and documented.

Spatial and temporal variability of greenhouse gas emissions from a small and shallow temperate lake

NASA Astrophysics Data System (ADS)

Praetzel, Leandra; Schmiedeskamp, Marcel; Broder, Tanja; Hüttemann, Caroline; Jansen, Laura; Metzelder, Ulrike; Wallis, Ronya; Knorr, Klaus-Holger; Blodau, Christian

2017-04-01

Small inland waters (< 1 km2) have recently been discovered as significant sources and sinks in the global carbon cycle because they cover larger areas than previously assumed and exhibit a higher metabolic activity than larger lakes. They are further expected to be susceptible to changing climate conditions. So far, little is known about the spatial and temporal variability of carbon dioxide (CO2) and methane (CH4) emissions and in-lake dynamics of CH4 production and oxidation in small, epilimnetic lakes in the temperate zone. Of particular interest is the potential occurrence of "hot spots" and "hot moments" that could contribute significantly to total emissions. To address this knowledge gap, we determined CO2 and CH4 emissions and dynamics to identify their controlling environmental factors in a polymictic small (1.4 ha) and shallow (max. depth approx. 1.5 m) crater lake ("Windsborn") in the Eifel uplands in south-west Germany. As Lake Windsborn has a small catchment area (8 ha) and no surficial inflows, it serves well as a model system for the identification of factors and processes controlling emissions. In 2015, 2016 and 2017 we measured CO2 and CH4 gas fluxes with different techniques across the sediment/water and water/atmosphere interface. Atmospheric exchange was measured using mini-chambers equipped with CO2 sensors and with an infra-red greenhouse gas analyzer for high temporal resolution flux measurements. Ebullition of CH4 was quantified with funnel traps. Sediment properties were examined using pore-water peepers. All measurements were carried out along a transect covering both littoral and central parts of the lake. Moreover, a weather station on a floating platform in the center of the lake recorded meteorological data as well as CO2 concentration in different depths of the water column. So far, Lake Windsborn seems to be a source for both CO2 and CH4 on an annual scale. CO2 emissions generally increased from spring to summer. Even though CO2 uptake could be observed during some periods in spring and fall, CO2 emissions in the summer exceeded the uptake. CO2 and CH4 emissions also appeared to be spatially variable between littoral areas and the inner lake. Shallow areas turned out to be "hot spots" of CO2 emissions whereas CH4 emissions were - against our expectations - highest in the center of the lake. Moreover, CH4 ebullition contributed substantially to total CH4 emissions. Our results show the importance of spatially and temporally highly resolved long-term measurements of greenhouse gas emissions and of potential controlling factors to address diurnal, seasonal and inter-annual variability as well as possible feedbacks to climate change.

Incinerator toxic emissions: a brief summary of human health effects with a note on regulatory control.

PubMed

Rowat, S C

1999-05-01

Toxic emissions from municipal solid waste (MSW) and hazardous waste incineration are discussed, with reference to recent reviews and to government standards and controls. Studies of known effects of aromatic hydrocarbons, other organics, dioxins, metals, and gases, on fish, soils, plants, and particularly humans are briefly reviewed. A summary of potential problems with existing and proposed incineration is developed, including: (1) lack of toxicity data on unidentified organic emissions; (2) unavoidability of hazardous metal emissions as particles and volatiles; (3) inefficient stack operation resulting in unknown amounts of increased emissions; (4) formation in the stack of highly toxic dioxins and furans, especially under inefficient conditions, and their build-up in the environment and in human tissue; (5) the lack of adequate disposal techniques for incinerator fly ash and wash-water; (6) the contribution of emitted gases such as NO2, SO2 and HCL to smog, acid rain, and the formation of ozone, and the deleterious effects of these on human respiratory systems; (7) the effects and build-up in human tissue of other emitted organics such as benzene, toluene, polychlorinated biphenyls (PCBs), alkanes, alcohols, and phenols; (8) lack of pollution-control and real-time efficiency-monitoring equipment in existing installations. The inability of regulatory bodies historically to ensure compliance with emission standards is discussed, and a concluding opinion is offered that it is inadvisable to engage in new incinerator construction with present knowledge and conditions.

[Characteristics of ammonia volatilization and nitrous oxide emission from a paddy soil under continuous application of different slow/controlled release urea.

PubMed

Sun, Xiang Xin; Li, Dong Po; Wu, Zhi Jie; Cui, Ya Lan; Han, Mei; Li, Yong Hua; Yang, De Fu; Cui, Yong Kun

2016-06-01

The characteristics of ammonia volatilization and nitrous oxide emission from a paddy soil were examined under 9-year application of different slow/controlled release urea with the common large granule urea (U) as the control. The results showed that compared with the control, all slow/controlled release urea treatments, except 25.8% increase of ammonia volatilization under 1% 3,4-dimethylpyrazole phosphate (DMPP)+U, could decrease the ammonia volatilization. Polymer coated urea (PCU) dominated the highest reduction of 73.4% compared to U, followed by sulfur coated urea (SCU) (72.2%), 0.5% N-(N-butyl) thiophosphoric triamide (NBPT)+1% DMPP+U (71.9%), 1% hydroquinone (HQ)+3% dicyandiamide (DCD)+U (46.9%), 0.5% NBPT+U (43.2%), 1% HQ +U (40.2%), 3% DCD+U (25.5%), and the ammonia volatilization under different slow/controlled release urea treatments were statistically lower than that of U (P<0.05). 1% DMPP+U caused the lowest emission of N 2 O under different slow/controlled release urea treatments. The slow/controlled release urea also had a significant potential of N 2 O emission reduction: 1% DMPP+U showed the highest reduction of 74.9% compared to U, followed by PCU (62.1%), 1% HQ+3% DCD+U (54.7%), 0.5% NBPT+1% DMPP+U (42.2%), 3% DCD+U (35.9%), 1% HQ +U (28.9%), 0.5% NBPT+U (17.7%), SCU (14.5%), and N 2 O emissions under different slow/controlled release urea treatments were statistically lower than that of U (P<0.05). The comprehensive analysis showed that 0.5% NBPT+1% DMPP+U, SCU and PCU had similar effects on decreasing the ammonia volatilization and N 2 O emission and were remarkably better than the other treatments. The slow release urea with the combination of urease and nitrification inhibitors should be the first choice for reducing N loss and environmental pollution in paddy field, in view of the higher costs of coated urea fertilizers.

Vehicle charging and potential on the STS-3 mission

NASA Technical Reports Server (NTRS)

Williamson, R.

1983-01-01

An electron gun with fast pulse capability was used in the vehicle charging and potential experiment carried on the OSS-1 pallet to study dielectric charging, return current mechanisms, and the techniques required to manage the electrical charging of the orbiter. Return currents and charging of the dielectrics were measured during electron beam emission and plasma characteristics in the payload bay were determined in the absence of electron beam emission. The fast pulse electron generator, charge current probes, spherical retarding potential analyzer, and the digital control interface unit which comprise the experiment are described. Results show that the thrusters produce disturbances which are variable in character and magnitude. Strong ram/wake effects were seen in the ion densities in the bay. Vehicle potentials are variable with respect to the plasma and depend upon location on the vehicle relative to the main engine nozzles, the vehicle attitude, and the direction of the geomagnetic field.

Differential controls by climate and physiology over the emission rates of biogenic volatile organic compounds from mature trees in a semi-arid pine forest.

PubMed

Eller, Allyson S D; Young, Lindsay L; Trowbridge, Amy M; Monson, Russell K

2016-02-01

Drought has the potential to influence the emission of biogenic volatile organic compounds (BVOCs) from forests and thus affect the oxidative capacity of the atmosphere. Our understanding of these influences is limited, in part, by a lack of field observations on mature trees and the small number of BVOCs monitored. We studied 50- to 60-year-old Pinus ponderosa trees in a semi-arid forest that experience early summer drought followed by late-summer monsoon rains, and observed emissions for five BVOCs-monoterpenes, methylbutenol, methanol, acetaldehyde and acetone. We also constructed a throughfall-interception experiment to create "wetter" and "drier" plots. Generally, trees in drier plots exhibited reduced sap flow, photosynthesis, and stomatal conductances, while BVOC emission rates were unaffected by the artificial drought treatments. During the natural, early summer drought, a physiological threshold appeared to be crossed when photosynthesis ≅2 μmol m(-2) s(-1) and conductance ≅0.02 mol m(-2) s(-1). Below this threshold, BVOC emissions are correlated with leaf physiology (photosynthesis and conductance) while BVOC emissions are not correlated with other physicochemical factors (e.g., compound volatility and tissue BVOC concentration) that have been shown in past studies to influence emissions. The proportional loss of C to BVOC emission was highest during the drought primarily due to reduced CO2 assimilation. It appears that seasonal drought changes the relations among BVOC emissions, photosynthesis and conductance. When drought is relaxed, BVOC emission rates are explained mostly by seasonal temperature, but when seasonal drought is maximal, photosynthesis and conductance-the physiological processes which best explain BVOC emission rates-decline, possibly indicating a more direct role of physiology in controlling BVOC emission.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sokhansanj, Shahabaddine; Kuang, Xingya; Shankar, T.S.

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 effectmore » 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.« less

Changing Atmospheric Acidity and the Oceanic Solubility of Nutrients

NASA Astrophysics Data System (ADS)

Baker, Alex; Sarin, Manmohan; Duce, Robert; Jickells, Tim; Kanakidou, Maria; Myriokefalitakis, Stelios; Ito, Akinori; Turner, David; Mahowald, Natalie; Middag, Rob; Guieu, Cecile; Gao, Yuan; Croot, Peter; Shelley, Rachel; Perron, Morgane

2017-04-01

The atmospheric deposition of nutrients to the ocean is known to play a significant role in the marine carbon cycle. The impact of such deposition is dependent on the identity of the nutrient in question (e.g., N, P, Fe, Co, Zn, Ni, Cd), the location of the deposition, and the bioavailability of the deposited nutrient. Bioavailability is largely governed by the chemical speciation of a nutrient and, in general, insoluble species are not bioavailable. For Fe and P (and perhaps the other nutrient trace metals) solubility increases during transport through the atmosphere. The causes of this increase are complex, but interactions of aerosol particles with acids appears to play a significant role. Emissions of acidic (SO2 and NOx) and alkaline (NH3) gases have increased significantly since the Industrial Revolution, with a net increase in atmospheric acidity. This implies that Fe and P solubility may also have increased over this time period, potentially resulting in increased marine productivity. More recently, pollution controls have decreased emissions of SO2 from some regions and further reductions in SO2 and NOx are likely in the future. Emissions of NH3 are much more difficult to control however, and are projected to stabilise or increase slightly to the end of this century. Future anthropogenic emissions are thus likely to change the acidity of the atmosphere downwind of major urban / industrial centres, with potential consequences for the supply of soluble nutrients to the ocean. To address these issues UN/GESAMP Working Group 38, The Atmospheric Input of Chemicals to the Ocean, is convening a workshop on this topic at the University of East Anglia in February, 2017. The goals of this workshop are to review and synthesize the current scientific information on the solubility of aerosol-associated key biogeochemical elements, the biogeochemical controls on aerosol solubility, and the pH sensitivity of those controls; to consider the likely changes in solubility of key species into the future and the potential biogeochemical consequences of such changes; and to identify the key future research needs to reduce uncertainties in predictive capability in this area. The results, conclusions, and recommendations of this workshop will be presented.

The Impact of a Potential Shale Gas Development in Germany and the United Kingdom on Local and Regional Air Quality

NASA Astrophysics Data System (ADS)

Weger, L.; Lupascu, A.; Cremonese, L.; Butler, T. M.

2017-12-01

Numerous countries in Europe that possess domestic shale gas reserves are considering exploiting this unconventional gas resource as part of their energy transition agenda. While natural gas generates less CO2 emissions upon combustion compared to coal or oil, making it attractive as a bridge in the transition from fossil fuels to renewables, production of shale gas leads to emissions of CH4 and air pollutants such as NOx, VOCs and PM. These gases in turn influence the climate as well as air quality. In this study, we investigate the impact of a potential shale gas development in Germany and the United Kingdom on local and regional air quality. This work builds on our previous study in which we constructed emissions scenarios based on shale gas utilization in these counties. In order to explore the influence of shale gas production on air quality, we investigate emissions predicted from our shale gas scenarios with the Weather Research and Forecasting model with chemistry (WRF-Chem) model. In order to do this, we first design a model set-up over Europe and evaluate its performance for the meteorological and chemical parameters. Subsequently we add shale gas emissions fluxes based on the scenarios over the area of the grid in which the shale gas activities are predicted to occur. Finally, we model these emissions and analyze the impact on air quality on both a local and regional scale. The aims of this work are to predict the range of adverse effects on air quality, highlight the importance of emissions control strategies in reducing air pollution, to promote further discussion, and to provide policy makers with information for decision making on a potential shale gas development in the two study countries.

Variable cycle engines for advanced supersonic transports

NASA Technical Reports Server (NTRS)

Howlett, R. A.; Kozlowski, H.

1975-01-01

Variable Cycle Engines being studied for advanced commercial supersonic transports show potential for significant environmental and economic improvements relative to 1st generation SST engines. The two most promising concepts are: a Variable Stream Control Engine and a Variable Cycle Engine with a rear flow-control valve. Each concept utilizes variable components and separate burners to provide independent temperature and velocity control for two coannular flow streams. Unique fuel control techniques are combined with cycle characteristics that provide low fuel consumption, similar to a turbojet engine, for supersonic operation. This is accomplished while retaining the good subsonic performance features of a turbofan engine. A two-stream coannular nozzle shows potential to reduce jet noise to below FAR Part 36 without suppressors. Advanced burner concepts have the potential for significant reductions in exhaust emissions. In total, these unique engine concepts have the potential for significant overall improvements to the environmental and economic characteristics of advanced supersonic transports.

Sub-arctic Wetland Greenhouse Gases (CO2, CH4 & N2O) Emissions are Driven by Interactions of Environmental Controls and Herbivore Grazers

NASA Astrophysics Data System (ADS)

Kelsey, K.; Leffler, A. J.; Beard, K. H.; Choi, R. T.; Welker, J. M.

2015-12-01

Climate change is increasing temperatures, altering precipitation regimes and causing earlier growing seasons, particularly at northern latitudes. Such changes in local environmental conditions have the potential to affect biogeochemical cycling including the exchange of greenhouses gases between the atmosphere and the terrestrial biosphere. In addition to the effects of these environmental controls, animals such as migratory geese also influence biogeochemical cycles through grazing, trampling and delivering nutrient-rich fecal matter. In this work we aimed to quantify how local environmental conditions and the presence of grazing interact as drivers of emissions of three key greenhouse gases, CO2, CH4 and N2O, in coastal wetlands of the Yukon Kuskokwim Delta. We explored the magnitude of emissions across gradients of soil temperature and water table depth, and across vegetation types related to the presence of grazing, ranging from no vegetation through grazed and ungrazed vegetation. We also investigated emissions from grazed areas using experimental manipulations of the timing of grazing and advancement of the growing season. We found that local environmental conditions and use by grazers exert interacting controls on emissions of CO2, CH4 and N2O. Emissions of CO2 and CH4 were positively related to soil temperature and CH4 emissions were inversely related to water table depth, but the relationship varied by vegetation type. Net emissions of CO2 were greatest in ungrazed vegetation types (6.62 umols CO2 m-2 sec-1; p=0.0007) whereas CH4 emissions were greatest in the grazed vegetation (122.56 nmols CH4 m-2 sec-1; p=0.037). Flux of N2O was less than 1 nmol N2O m-2 sec-1 across all landscape positions under typical grazing and temperature conditions, but emissions were stimulated to over 10 nmols m-2 sec-1 when grazing occurred early relative to a typical season. Our results indicate that environmental conditions and the presence of migratory herbivores are both important controls on gas fluxes. Future climate change may alter regional gas flux and biosphere-atmosphere feedbacks both via direct environmental drivers and through climate-driven changes to populations or habits of grazers that also exert important controls on biogeochemical cycling in this region.

Low frequency aeration of pig slurry affects slurry characteristics and emissions of greenhouse gases and ammonia.

PubMed

Calvet, Salvador; Hunt, John; Misselbrook, Tom H

2017-07-01

Low frequency aeration of slurries may reduce ammonia (NH 3 ) and methane (CH 4 ) emissions without increasing nitrous oxide (N 2 O) emissions. The aim of this study was to quantify this potential reduction and to establish the underlying mechanisms. A batch experiment was designed with 6 tanks with 1 m 3 of pig slurry each. After an initial phase of 7 days when none of the tanks were aerated, a second phase of 4 weeks subjected three of the tanks to aeration (2 min every 6 h, airflow 10 m 3  h -1 ), whereas the other three tanks remained as a control. A final phase of 9 days was established with no aeration in any tank. Emissions of NH 3 , CH 4 , carbon dioxide (CO 2 ) and N 2 O were measured. In the initial phase no differences in emissions were detected, but during the second phase aeration increased NH 3 emissions by 20% with respect to the controls (8.48 vs. 7.07 g m -3  [slurry] d -1 , P < 0.05). A higher pH was found in the aerated tanks at the end of this phase (7.7 vs. 7.0 in the aerated and control tanks, respectively, P < 0.05). CH 4 emissions were 40% lower in the aerated tanks (2.04 vs. 3.39 g m -3  [slurry] d -1 , P < 0.05). These differences in NH 3 and CH 4 emissions remained after the aeration phase had finished. No effect was detected for CO 2 , and no relevant N 2 O emissions were detected during the experiment. Our results demonstrate that low frequency aeration of stored pig slurry increases slurry pH and increases NH 3 emissions.

Near Infrared Emission from Defects in Few-Layer Phosphorene

NASA Astrophysics Data System (ADS)

Aghaeimeibodi, Shahriar; Kim, Je-Hyung; Waks, Edo

Atomically thin films of black phosphorus have recently received significant attention as low dimensional optical materials with a direct exciton emission whose wavelength is tunable by controlling the number of layers. In addition to this excitonic emission, recent work has revealed emission from defect states and reported new methods to manipulate them. Monolayer phosphorene exhibits emission from localized defect states at wavelengths near 920 nm. Increasing the number of layers should shift defect emission to longer wavelengths, enabling the material to span a broader spectral range. But defect emission from few-layer phosphorene has not yet been reported. Here, we demonstrate a new class of near infrared defects in few layer phosphorene. Photoluminescence measurement shows a bright emission around 1240 nm with a sublinear growth of emission intensity with linear increase of excitation intensity, confirming the defect nature of this emission. From time-resolved lifetime measurements we determine an emission lifetime of 1.2 ns, in contrast to exciton and trion lifetimes from few layer phosphorene previously reported to be in the range of a few hundred picoseconds. This work highlights the potential of bright defects of phosphorene for near infrared optoelectronic applications.

Isoprene emission protects photosynthesis but reduces plant productivity during drought in transgenic tobacco (Nicotiana tabacum) plants.

PubMed

Ryan, Annette C; Hewitt, C Nicholas; Possell, Malcolm; Vickers, Claudia E; Purnell, Anna; Mullineaux, Philip M; Davies, William J; Dodd, Ian C

2014-01-01

Isoprene protects the photosynthetic apparatus of isoprene-emitting plants from oxidative stress. The role of isoprene in the response of plants to drought is less clear. Water was withheld from transgenic isoprene-emitting and non-emitting tobacco (Nicotiana tabacum) plants, to examine: the response of isoprene emission to plant water deficit; a possible relationship between concentrations of the drought-induced phytohormone abscisic acid (ABA) and isoprene; and whether isoprene affected foliar reactive oxygen species (ROS) and lipid peroxidation levels. Isoprene emission did not affect whole-plant water use, foliar ABA concentration or leaf water potential under water deficit. Compared with well-watered controls, droughted non-emitting plants significantly increased ROS content (31-46%) and lipid peroxidation (30-47%), concomitant with decreased operating and maximum efficiencies of photosystem II photochemistry and lower leaf and whole-plant water use efficiency (WUE). Droughted isoprene-emitting plants showed no increase in ROS content or lipid peroxidation relative to well-watered controls, despite isoprene emission decreasing before leaf wilting. Although isoprene emission protected the photosynthetic apparatus and enhanced leaf and whole-plant WUE, non-emitting plants had 8-24% more biomass under drought, implying that isoprene emission incurred a yield penalty. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Effect of spent mushroom substrate as a bulking agent on gaseous emissions and compost quality during pig manure composting.

PubMed

Li, Shuyan; Li, Danyang; Li, Jijin; Li, Yangyang; Li, Guoxue; Zang, Bing; Li, Yun

2018-05-01

The aim of this study was to investigate the gaseous emissions (CH 4 , N 2 O, and NH 3 ) and compost quality during the pig manure composting by adding spent mushroom substrate (SMS) as a bulking agent. The control treatment was also studied using corn stalk (CS) as a bulking agent. The experiment was conducted in a pilot scale composting reactor under aerobic condition with the initial C/N ratio of 20. Results showed that bulking agents significantly affected gaseous emissions and compost quality. Using SMS as a bulking agent improved composting efficiency by shortening the time for maturity. SMS increased germination index and humic acid of the final compost (by 13.44 and 41.94%, respectively) compared with CS. Furthermore, composting with SMS as a bulking agent could reduce nitrogen loss, NH 3 , and N 2 O emissions (by 13.57, 35.56, and 46.48%, respectively) compared with the control. SMS slightly increased CH 4 emission about 1.1 times of the CS. However, a 33.95% decrease in the global warming potential of CH 4 and N 2 O was obtained by adding SMS treatment. These results indicate that SMS is a favorable bulking agent for reducing gaseous emissions and increasing compost quality.

Ozone and its potential control strategy for Chon Buri city, Thailand.

PubMed

Prabamroong, Thayukorn; Manomaiphiboon, Kasemsan; Limpaseni, Wongpun; Sukhapan, Jariya; Bonnet, Sebastien

2012-12-01

This work studies O3 pollution for Chon Buri city in the eastern region of Thailand, where O3 has become an increased and serious concern in the last decade. It includes emission estimation and photochemical box modeling in support of investigating the underlying nature of O3 formation over the city and the roles of precursors emitted from sources. The year 2006 was considered and two single-day episodes (January 29 and February 14) were chosen for simulations. It was found that, in the city, the industrial sector is the largest emissions contributor for every O3 precursor (i.e., NO(x), non-methane volatile organic compounds or NMVOC, and CO), followed by on-road mobile group. Fugitive NMVOC is relatively large, emitted mainly from oil refineries and tank farms. Simulated results acceptably agree with observations for daily maximum O3 level in both episodes and evidently indicate the VOC-sensitive regime for O3 formation. This regime is also substantiated by morning NMVOC/NO(x) ratios observed in the city. The corresponding O3 isopleth diagrams suggest NMVOC control alone to lower elevated O3. In seeking a potential O3 control strategy for the city, a combination of brute-force sensitivity tests, an experimental design, statistical modeling, and cost optimization was employed. A number of emission subgroups were found to significantly contribute to O3 formation, based on the February 14 episode, for example, oil refinery (fugitive), tank farm (fugitive), passenger car (gasoline), and motorcycle (gasoline). But the cost-effective strategy suggests control only on the first two subgroups to meet the standard. The cost of implementing the strategy was estimated and found to be small (only 0.2%) compared to the gross provincial product generated by the entire province where the city is located within. These findings could be useful as a needed guideline to support O3 management for the city. Elevated O3 in the urban and industrial city of Chon Buri needs better understanding of the problem and technical guidelines for its management. With a city-specific emission inventory and air quality modeling, O3 formation was found to be VOC sensitive, and a cost-effective control strategy developed highlights fugitive emissions from the industrial sector to be controlled.

Elucidating secondary organic aerosol from diesel and gasoline vehicles through detailed characterization of organic carbon emissions

PubMed Central

Gentner, Drew R.; Isaacman, Gabriel; Worton, David R.; Chan, Arthur W. H.; Dallmann, Timothy R.; Davis, Laura; Liu, Shang; Day, Douglas A.; Russell, Lynn M.; Wilson, Kevin R.; Weber, Robin; Guha, Abhinav; Harley, Robert A.; Goldstein, Allen H.

2012-01-01

Emissions from gasoline and diesel vehicles are predominant anthropogenic sources of reactive gas-phase organic carbon and key precursors to secondary organic aerosol (SOA) in urban areas. Their relative importance for aerosol formation is a controversial issue with implications for air quality control policy and public health. We characterize the chemical composition, mass distribution, and organic aerosol formation potential of emissions from gasoline and diesel vehicles, and find diesel exhaust is seven times more efficient at forming aerosol than gasoline exhaust. However, both sources are important for air quality; depending on a region’s fuel use, diesel is responsible for 65% to 90% of vehicular-derived SOA, with substantial contributions from aromatic and aliphatic hydrocarbons. Including these insights on source characterization and SOA formation will improve regional pollution control policies, fuel regulations, and methodologies for future measurement, laboratory, and modeling studies. PMID:23091031

Development of on-board fuel metering and sensing system

NASA Astrophysics Data System (ADS)

Hemanth, Y.; Manikanta, B. S. S.; Thangaraja, J.; Bharanidaran, R.

2017-11-01

Usage of biodiesel fuels and their blends with diesel fuel has a potential to reduce the tailpipe emissions and reduce the dependence on crude oil imports. Further, biodiesel fuels exhibit favourable greenhouse gas emission and energy balance characteristics. While fossil fuel technology is well established, the technological implications of biofuels particularly biodiesel is not clearly laid out. Hence, the objective is to provide an on-board metering control in selecting the different proportions of diesel and bio-diesel blends. An on-board fuel metering system is being developed using PID controller, stepper motors and a capacitance sensor. The accuracy was tested with the blends of propanol-1, diesel and are found to be within 1.3% error. The developed unit was tested in a twin cylinder diesel engine with biodiesel blended diesel fuel. There was a marginal increase (5%) in nitric oxide and 14% increase in smoke emission with 10% biodiesel blended diesel at part load conditions.

Elucidating secondary organic aerosol from diesel and gasoline vehicles through detailed characterization of organic carbon emissions.

PubMed

Gentner, Drew R; Isaacman, Gabriel; Worton, David R; Chan, Arthur W H; Dallmann, Timothy R; Davis, Laura; Liu, Shang; Day, Douglas A; Russell, Lynn M; Wilson, Kevin R; Weber, Robin; Guha, Abhinav; Harley, Robert A; Goldstein, Allen H

2012-11-06

Emissions from gasoline and diesel vehicles are predominant anthropogenic sources of reactive gas-phase organic carbon and key precursors to secondary organic aerosol (SOA) in urban areas. Their relative importance for aerosol formation is a controversial issue with implications for air quality control policy and public health. We characterize the chemical composition, mass distribution, and organic aerosol formation potential of emissions from gasoline and diesel vehicles, and find diesel exhaust is seven times more efficient at forming aerosol than gasoline exhaust. However, both sources are important for air quality; depending on a region's fuel use, diesel is responsible for 65% to 90% of vehicular-derived SOA, with substantial contributions from aromatic and aliphatic hydrocarbons. Including these insights on source characterization and SOA formation will improve regional pollution control policies, fuel regulations, and methodologies for future measurement, laboratory, and modeling studies.

Reduction of CO2 and orbital debris: can CO2 emission trading principles be applied to debris reduction?

NASA Astrophysics Data System (ADS)

Orlando, Giovanni; Kinnersley, Mark; Starke, Juergen; Hugel, Sebastian; Hartner, Gloria; Singh, Sanjay; Loubiere, Vincent; Staebler, Dominik-Markus; O'Brien-Organ, Christopher; Schwindt, Stefan; Serreau, Francois; Sharma, Mohit

In the past years global pollution and the specific situation of global warming changes have been strongly influencing public opinion and thus obliged politicians to initiate/ negotiate in-ternational agreements to control, avoid or at least reduce the impact of CO2 emissions e.g. The Kyoto Protocol (1997) and the International Copenhagen conference on Climate Change (2009). In the orbital debris area the collision between the Iridium33 and Cosmos 2251 satel-lites in 2009 has again pushed to the forefront the discussion of the space pollution by space debris and the increasing risk of critical and catastrophic events during the nominal life time of space objects. It is shown by simulations that for Low Earth Orbits the critical debris situation is already achieved and the existing space objects will probably produce sufficient space debris elements -big enough -to support the cascade effect (Kessler Syndrome). In anal-ogy with CO2 emissions, potential recommendations / regulations to reduce the production of Space Debris or its permanence in orbit, are likely to open new markets involving Miti-gation and Removal of Space Debris. The principle approach for the CO2 emission trading model will be investigated and the applicability for the global space debris handling will be analysed. The major differences of the two markets will be derived and the consequences in-dicated. Potential alternative solutions will be proposed and discussed. For the example of the CO2 emission trading principles within EU and worldwide legal conditions for space debris (national / international laws and recommendations) will be considered as well as the commer-cial approach from the controlled situation of dedicated orders to a free / competitive market in steps. It is of interest to consider forms of potential industrial organisations and interna-tional co-operations to react on a similar architecture for the debris removal trading including incentives and penalties for the different potential customers as satellite operators, agencies or international organisations Giovanni.Orlando@astrium.eads.net Tel.: +49-421-539-4032 juergen.starke@astrium.eads.net Tel.: +49-421-539-4573

Global Warming Potential and Eutrophication Potential of Biofuel Feedstock Crops Produced in Florida, Measured Under Different Scenarios

DOE Office of Scientific and Technical Information (OSTI.GOV)

Izursa, Jose-Luis; Hanlon, Edward; Amponsah, Nana

2013-02-15

The agriculture sector is in a growing need to develop greenhouse gas (GHG) mitigation techniques to reduce the enhanced greenhouse effect. The challenge to the sector is not only to reduce net emissions but also increase production to meet growing demands for food, fiber, and biofuel. This study focuses on the changes in the GHG balance of three biofuel feedstock (biofuel sugarcane, energy-cane and sweet sorghum) considering changes caused by the adoption of conservationist practices such as reduced tillage, use of controlled-release fertilizers or when cultivation areas are converted from burned harvest to green harvest. Based on the Intergovernmental Panelmore » on Climate Change (IPCC) (2006) balance and the Tools for the Reduction and Assessment of Chemical and Other Environmental Impacts (TRACI) characterization factors published by the EPA, the annual emission balance includes use energy (diesel and electricity), equipment, and ancillary materials, according to the mean annual consumption of supplies per hectare. The total amounts of GWP were 2740, 1791, and 1910 kg CO2e ha-1 y-1 for biofuel sugarcane, energy-cane and sweet sorghum, respectively, when produced with conventional tillage and sugarcane was burned prior to harvesting. Applying reduced tillage practices, the GHG emissions reduced to 13% for biofuel sugarcane, 23% for energy-cane and 8% for sweet sorghum. A similar decrease occurs when a controlled-release fertilizer practice is adopted, which helps reduce the total emission balance in 5%, 12% and 19% for biofuel sugarcane, energy-cane and sweet sorghum, respectively and a 31% average reduction in eutrophication potential. Moreover, the GHG emissions for biofuel sugarcane, with the adoption of green harvest, would result in a smaller GHG balance of 1924 kg CO2e ha-1 y-1, providing an effect strategy for GHG mitigation while still providing a profitable yield in Florida.« less

Molecular mechanisms of water table lowering and nitrogen deposition in affecting greenhouse gas emissions from a Tibetan alpine wetland.

PubMed

Wang, Hao; Yu, Lingfei; Zhang, Zhenhua; Liu, Wei; Chen, Litong; Cao, Guangmin; Yue, Haowei; Zhou, Jizhong; Yang, Yunfeng; Tang, Yanhong; He, Jin-Sheng

2017-02-01

Rapid climate change and intensified human activities have resulted in water table lowering (WTL) and enhanced nitrogen (N) deposition in Tibetan alpine wetlands. These changes may alter the magnitude and direction of greenhouse gas (GHG) emissions, affecting the climate impact of these fragile ecosystems. We conducted a mesocosm experiment combined with a metagenomics approach (GeoChip 5.0) to elucidate the effects of WTL (-20 cm relative to control) and N deposition (30 kg N ha -1  yr -1 ) on carbon dioxide (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O) fluxes as well as the underlying mechanisms. Our results showed that WTL reduced CH 4 emissions by 57.4% averaged over three growing seasons compared with no-WTL plots, but had no significant effect on net CO 2 uptake or N 2 O flux. N deposition increased net CO 2 uptake by 25.2% in comparison with no-N deposition plots and turned the mesocosms from N 2 O sinks to N 2 O sources, but had little influence on CH 4 emissions. The interactions between WTL and N deposition were not detected in all GHG emissions. As a result, WTL and N deposition both reduced the global warming potential (GWP) of growing season GHG budgets on a 100-year time horizon, but via different mechanisms. WTL reduced GWP from 337.3 to -480.1 g CO 2 -eq m -2 mostly because of decreased CH 4 emissions, while N deposition reduced GWP from 21.0 to -163.8 g CO 2 -eq m -2 , mainly owing to increased net CO 2 uptake. GeoChip analysis revealed that decreased CH 4 production potential, rather than increased CH 4 oxidation potential, may lead to the reduction in net CH 4 emissions, and decreased nitrification potential and increased denitrification potential affected N 2 O fluxes under WTL conditions. Our study highlights the importance of microbial mechanisms in regulating ecosystem-scale GHG responses to environmental changes. © 2016 John Wiley & Sons Ltd.

Understanding Emissions from Control-Related Equipment used in Oil and Gas Production Operations to Support EPA’s Air Quality Modeling of Ozone Non-attainment Areas

EPA Science Inventory

Oil and gas production has increased significantly in the United States over the past ten years. Improperly maintained and controlled oil and gas extraction and production (E&P) processes have the potential to emit significant amounts of pollutants that can impact human health an...

Controls on boreal peat combustion and resulting emissions of carbon and mercury

NASA Astrophysics Data System (ADS)

Kohlenberg, Andrew J.; Turetsky, Merritt R.; Thompson, Dan K.; Branfireun, Brian A.; Mitchell, Carl P. J.

2018-03-01

Warming in the boreal forest region has already led to changes in the fire regime. This may result in increasing fire frequency or severity in peatlands, which could cause these ecosystems to shift from a net sink of carbon (C) to a net source of C to the atmosphere. Similar to C cycling, peatlands serve as a net sink for mercury (Hg), which binds strongly to organic matter and accumulates in peat over time. This stored Hg is also susceptible to re-release to the atmosphere during peat fires. Here we investigate the physical properties that influence depth of burn in experimental peat columns and the resulting emissions of CO, CO2, CH4, and gaseous and particulate Hg. As expected, bulk density and soil moisture content were important controls on depth of burn, CO2 emissions, and CO emissions. However, our results show that CH4 and Hg emissions are insensitive to combustion temperature or fuel moisture content. Emissions during the burning of peat, across a wide range of moisture conditions, were associated with low particulate Hg and high gaseous Hg release. Due to strong correlations between total Hg and CO emissions and because high Hg emissions occurred despite incomplete combustion of total C, our results suggest that Hg release during peat burning is governed by the thermodynamics of Hg reduction more so than by the release of Hg associated with peat combustion. Our measured emissions ratios, particularly for CH4:CO2, are higher than values typically used in the upscaling of boreal forest or peatland fire emissions. These emission ratios have important implications not only for our understanding of smouldering chemistry, but also for potential influences of peat fires on the Earth’s climate system.

Comparison of on-road emissions for hybrid and regular transit buses.

PubMed

Hallmark, Shauna L; Wang, Bo; Sperry, Robert

2013-10-01

Hybrid technology offers an attractive option for transit buses, since it has the potential to significantly reduce operating costs for transit agencies. The main impetus behind use of hybrid transit vehicles is fuel savings and reduced emissions. Laboratory tests have indicated that hybrid transit buses can have significantly lower emissions compared with conventional transit buses. However the number of studies is limited and laboratory tests may not represent actual driving conditions, since in-use vehicle operation differs from laboratory test cycles. This paper describes an on-road evaluation of in-use emission differences between hybrid-electric and conventional transit buses for the Ames, Iowa transit authority, CyRide. Emissions were collected on-road using a portable emissions monitoring system (PEMS) for three hybrid and two control buses. Emissions were collected for at least one operating bus day. Each bus was evaluated over the same route pattern, which utilizes the same driver. The number of passengers embarking or disembarking at each stop was collected by an on-board data collector so that passenger load could be included. Vehicle emissions are correlated to engine load demand, which is a function of factors such as vehicle load, speed, and acceleration. PEMS data are provided second by second and vehicle-specific power (VSP) was calculated for each row of data. Instantaneous data were stratified into the defined VSP bins and then average modal emission rates and standard errors were calculated for each bus for each pollutant. Pollutants were then compared by bus type. Carbon dioxide, carbon monoxide, and hydrocarbon emissions were higher for the regular buses across most VSP bins than for the hybrid buses. Nitrogen oxide emissions were unexpectedly higher for the hybrid buses than for the control buses.

Quantitative assessment of industrial VOC emissions in China: Historical trend, spatial distribution, uncertainties, and projection

NASA Astrophysics Data System (ADS)

Zheng, Chenghang; Shen, Jiali; Zhang, Yongxin; Huang, Weiwei; Zhu, Xinbo; Wu, Xuecheng; Chen, Linghong; Gao, Xiang; Cen, Kefa

2017-02-01

The temporal trends of industrial volatile organic compound (VOC) emissions was comprehensively summarized for the 2011 to 2013 period, and the projections for 2020 to 2050 for China were set. The results demonstrate that industrial VOC emissions in China increased from 15.3 Tg in 2011 to 29.4 Tg in 2013 at an annual average growth rate of 38.3%. Guangdong (3.45 Tg), Shandong (2.85 Tg), and Jiangsu (2.62 Tg) were the three largest contributors collectively accounting for 30.4% of the national total emissions in 2013. The top three average industrial VOC emissions per square kilometer were Shanghai (247.2 ton/km2), Tianjin (62.8 ton/km2), and Beijing (38.4 ton/km2), which were 12-80 times of the average level in China. The data from the inventory indicate that the use of VOC-containing products, as well as the production and use of VOCs as raw materials, as well as for storage and transportation contributed 75.4%, 10.3%, 9.1%, and 5.2% of the total emissions, respectively. ArcGIS was used to display the remarkable spatial distribution variation by allocating the emission into 1 km × 1 km grid cells with a population as surrogate indexes. Combined with future economic development and population change, as well as implementation of policy and upgrade of control technologies, three scenarios (scenarios A, B, and C) were set to project industrial VOC emissions for the years 2020, 2030, and 2050, which present the industrial VOC emissions in different scenarios and the potential of reducing emissions. Finally, the result shows that the collaborative control policies considerably influenced industrial VOC emissions.

Air toxics provisions of the Clean Air Act: Potential impacts on energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hootman, H.A.; Vernet, J.E.

1991-11-01

This report provides an overview of the provisions of the Clean Air Act and its Amendments of 1990 that identify hazardous air pollutant (HAP) emissions and addresses their regulation by the US Environmental Protection Agency (EPA). It defines the major energy sector sources of these HAPs that would be affected by the regulations. Attention is focused on regulations that would cover coke oven emissions; chromium emission from industrial cooling towers and the electroplating process; HAP emissions from tank vessels, asbestos-related activities, organic solvent use, and ethylene oxide sterilization; and emissions of air toxics from municipal waste combustors. The possible implicationsmore » of Title III regulations for the coal, natural gas, petroleum, uranium, and electric utility industries are examined. The report discusses five major databases of HAP emissions: (1) TRI (EPA's Toxic Release Inventory); (2) PISCES (Power Plant Integrated Systems: Chemical Emissions Studies developed by the Electric Power Research Institute); (3) 1985 Emissions Inventory on volatile organic compounds (used for the National Acid Precipitation Assessment Program); (4) Particulate Matter Species Manual (EPA); and (5) Toxics Emission Inventory (National Aeronautics and Space Administration). It also offers information on emission control technologies for municipal waste combustors.« less

Air toxics provisions of the Clean Air Act: Potential impacts on energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hootman, H.A.; Vernet, J.E.

1991-11-01

This report provides an overview of the provisions of the Clean Air Act and its Amendments of 1990 that identify hazardous air pollutant (HAP) emissions and addresses their regulation by the US Environmental Protection Agency (EPA). It defines the major energy sector sources of these HAPs that would be affected by the regulations. Attention is focused on regulations that would cover coke oven emissions; chromium emission from industrial cooling towers and the electroplating process; HAP emissions from tank vessels, asbestos-related activities, organic solvent use, and ethylene oxide sterilization; and emissions of air toxics from municipal waste combustors. The possible implicationsmore » of Title III regulations for the coal, natural gas, petroleum, uranium, and electric utility industries are examined. The report discusses five major databases of HAP emissions: (1) TRI (EPA`s Toxic Release Inventory); (2) PISCES (Power Plant Integrated Systems: Chemical Emissions Studies developed by the Electric Power Research Institute); (3) 1985 Emissions Inventory on volatile organic compounds (used for the National Acid Precipitation Assessment Program); (4) Particulate Matter Species Manual (EPA); and (5) Toxics Emission Inventory (National Aeronautics and Space Administration). It also offers information on emission control technologies for municipal waste combustors.« less

Reduced Binding Potential of GABA-A/Benzodiazepine Receptors in Individuals at Ultra-high Risk for Psychosis: An [18F]-Fluoroflumazenil Positron Emission Tomography Study

PubMed Central

Kang, Jee In; Park, Hae-Jeong; An, Suk Kyoon

2014-01-01

Background: Altered transmission of gamma-aminobutyric acid (GABA), a major inhibitory neurotransmitter, may contribute to the development of schizophrenia. The purpose of the present study was to investigate the presence of GABA-A/benzodiazepine (BZ) receptor binding abnormalities in individuals at ultra-high risk (UHR) for psychosis in comparison with normal controls using [18F]-fluoroflumazenil (FFMZ) positron emission tomography (PET). In particular, we set regions of interest in the striatum (caudate, putamen, and nucleus accumbens) and medial temporal area (hippocampus and parahippocampal gyrus). Methods: Eleven BZ-naive people at UHR and 15 normal controls underwent PET scanning using [18F]-FFMZ to measure GABA-A/BZ receptor binding potential. The regional group differences between UHR individuals and normal controls were analyzed using Statistical Parametric Mapping 8 software. Participants were evaluated using the structured interview for prodromal syndromes and neurocognitive function tasks. Results: People at UHR demonstrated significantly reduced binding potential of GABA-A/BZ receptors in the right caudate. Conclusions: Altered GABAergic transmission and/or the imbalance of inhibitory and excitatory systems in the striatum may be present at the putative prodromal stage and play a pivotal role in the pathophysiology of psychosis. PMID:23588475

Comparison of nitrogen monoxide emissions from several African tropical ecosystems and influence of season and fire

NASA Astrophysics Data System (ADS)

SerçA, D.; Delmas, R.; Le Roux, X.; Parsons, D. A. B.; Scholes, M. C.; Abbadie, L.; Lensi, R.; Ronce, O.; Labroue, L.

1998-12-01

NO emission rates from soils were measured for twelve major African ecosystems in four countries (Congo, Niger, Ivory Coast, and South Africa) and within four major phytogeographic domains: the Guineo-Congolese, Guinean, Sahelian, and Zambezian domains. Measurements were performed during wet and/or dry seasons. All the measurements were made with the same dynamic chamber device, which allowed true comparisons to be made. This study showed that emission rates strongly differed between ecosystems and exhibited a marked temporal variability. Ecosystem effect was highly significant during both the dry and wet seasons. Emission rates were low (<0.6 ng NO-N m-2 s-1) in Hyparrhenia and Loudetia savannas of the Guinean or Guineo-Congolese domains. Intermediate NO fluxes were obtained in rain forest and gallery forest ecosystems, in a broad-leafed savanna and in a seasonally wetted grassland (sandy soil) of the Zambezian domain, and in a dry fallow savanna of the Sahelian domain. Emission rates were maximum (>7 ng NO-N m-2 s-1) in a seasonally wetted grassland (site 2) and in particular sites subjected to various disturbances, for example soil fauna activity (termite mounds) or past human disturbance (Acacia patches-settlement site). Microbial activity potentials (i.e., carbon mineralization, nitrification, denitrification, and total net N mineralization) were determined for most of the soils where NO fluxes were measured. In some sites, these potential activities were useful to identify the major processes controlling NO emission rates. Denitrification potential was very low and could not explain substantial NO fluxes from broad- and fine-leafed savannas and Hyperihelia savannas of the Zambezian domain. Very low potentials of both nitrification and denitrification could be related to the low NO fluxes for the three Guinean savanna sites studied. NO fluxes were significantly higher during the wet season than the dry season in both savanna and forest ecosystems. Emission rates in savanna ecosystems were significantly increased within a few hours after fire. The measurements presented here provide a unique, consistent database which can be used to further analyze the processes involved in the spatial and temporal variations of NO emissions.

Nano-metal oxides: Exposure and engineering control assessment.

PubMed

Garcia, Alberto; Eastlake, Adrienne; Topmiller, Jennifer L; Sparks, Christopher; Martinez, Kenneth; Geraci, Charles L

2017-09-01

In January 2007, the National Institute for Occupational Safety and Health (NIOSH) conducted a field study to evaluate process specific emissions during the production of ENMs. This study was performed using the nanoparticle emission assessment technique (NEAT). During this study, it was determined that ENMs were released during production and cleaning of the process reactor. Airborne concentrations of silver, nickel, and iron were found both in the employee's personal breathing zone and area samples during reactor cleaning. At the completion of this initial survey, it was suggested that a flanged attachment be added to the local exhaust ventilation system.  NIOSH re-evaluated the facility in December 2011 to assess worker exposures following an increase in production rates. This study included a fully comprehensive emissions, exposure, and engineering control evaluation of the entire process. This study made use of the nanoparticle exposure assessment technique (NEAT 2.0). Data obtained from filter-based samples and direct reading instruments indicate that reactor cleanout increased the overall particle concentration in the immediate area. However, it does not appear that these concentrations affect areas outside of the production floor. As the distance between the reactor and the sample location increased, the observed particle number concentration decreased, creating a concentration gradient with respect to the reactor. The results of this study confirm that the flanged attachment on the local exhaust ventilation system served to decrease exposure potential.  Given the available toxicological data of the metals evaluated, caution is warranted. One should always keep in mind that occupational exposure levels were not developed specifically for nanoscale particles. With data suggesting that certain nanoparticles may be more toxic than the larger counterparts of the same material; employers should attempt to control emissions of these particles at the source, to limit the potential for exposure.

Non-agricultural ammonia emissions in urban China

NASA Astrophysics Data System (ADS)

Chang, Y. H.

2014-03-01

The non-agricultural ammonia (NH3) emissions in cities have received little attention but could rival agricultural sources in term of the efficiency in PM formation. The starting point for finding credible solutions is to comprehensively establish a city-specific Non-agricultural Ammonia Emission Inventory (NAEI) and identify the largest sources where efforts can be directed to deliver the largest impact. In this paper, I present a NAEI of 113 national key cities targeted on environmental protection in China in 2010, which for the first time covers NH3 emissions from pets, infants, smokers, green land, and household products. Results show that totally 210 478 Mg, the NH3 emissions from traffic, fuel combustion, waste disposal, pets, green land, human, and household products are 67 671 Mg, 56 275 Mg, 44 289 Mg, 23 355 Mg, 7509 Mg, 7312 Mg, and 4069 Mg, respectively. The NH3 emission intensity from the municipal districts ranges from 0.08 to 3.13 Mg km-2 yr-1, with a average of 0.84 Mg km-2 yr-1. The high NH3 emission intensities in Beijing-Tianjin-Hebei region, Yangtze River Delta region and Pearl River Delta region support the view that non-agricultural NH3 sources play a key role in city-scale NH3 emissions and thus have potentially important implications for secondary PM formation (ammonium-sulfate-nitrate system) in urban agglomeration of China. Therefore, in addition to current SO2 and NOx controls, China also needs to allocate more scientific, technical, and legal resources on controlling non-agricultural NH3 emissions in the future.

PREDICTION OF FORBIDDEN ULTRAVIOLET AND VISIBLE EMISSIONS IN COMET 67P/CHURYUMOV–GERASIMENKO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raghuram, Susarla; Galand, Marina; Bhardwaj, Anil, E-mail: raghuramsusarla@gmail.com

Remote observation of spectroscopic emissions is a potential tool for the identification and quantification of various species in comets. The CO Cameron band (to trace CO{sub 2}) and atomic oxygen emissions (to trace H{sub 2}O and/or CO{sub 2}, CO) have been used to probe neutral composition in the cometary coma. Using a coupled-chemistry-emission model, various excitation processes controlling the CO Cameron band and different atomic oxygen and atomic carbon emissions have been modeled in comet 67P/Churyumov–Gerasimenko at 1.29 AU (perihelion) and at 3 AU heliocentric distances, which is being explored by ESA's Rosetta mission. The intensities of the CO Cameronmore » band, atomic oxygen, and atomic carbon emission lines as a function of projected distance are calculated for different CO and CO{sub 2} volume mixing ratios relative to water. Contributions of different excitation processes controlling these emissions are quantified. We assess how CO{sub 2} and/or CO volume mixing ratios with respect to H{sub 2}O can be derived based on the observed intensities of the CO Cameron band, atomic oxygen, and atomic carbon emission lines. The results presented in this work serve as baseline calculations to understand the behavior of low out-gassing cometary coma and compare them with the higher gas production rate cases (e.g., comet Halley). Quantitative analysis of different excitation processes governing the spectroscopic emissions is essential to study the chemistry of inner coma and to derive neutral gas composition.« less

A spectral method for spatial downscaling

EPA Science Inventory

Complex computer models play a crucial role in air quality research. These models are used to evaluate potential regulatory impacts of emission control strategies and to estimate air quality in areas without monitoring data. For both of these purposes, it is important to calibrat...

A Framework for Evaluating Energy and Emissions of Connected and Automated Vehicles through Traffic Microsimulations

DOT National Transportation Integrated Search

2018-01-07

Connected and automated vehicles (CAV) are poised to transform surface transportation systems in the United States. Near-term CAV technologies like cooperative adaptive cruise control (CACC) have the potential to deliver energy efficiency and air qua...

Prescribed Grassland Burning Smoke Emission Measurements in the Northern Flint Hills Region

EPA Science Inventory

Historically, frequent wildfires were essential for the maintenance of native prairie fire adapted ecosystems. Today prescribed fires are used to control invasive woody species and potentially improve forage production in these same prairie ecosystems for the beef-cattle industry...

Management matters: Testing a mitigation strategy of nitrous oxide emissions on managed grassland

NASA Astrophysics Data System (ADS)

Fuchs, Kathrin; Hörtnagl, Lukas; Eugster, Werner; Koller, Patrick; Käslin, Florian; Merbold, Lutz

2017-04-01

The magnitude of greenhouse gas (GHG) exchange between managed grasslands and the atmosphere depends besides climate predominantly on management practices. While natural or extensively managed grasslands are known to function as GHG sinks, intensively managed grasslands are characterized by substantial nitrous oxide (N2O) emissions diminishing their sink function. One potential N2O mitigation strategy is to reduce the required amount of nitrogen (N) fertilizer input by using biological nitrogen fixation (BNF) via legumes. However, the effect of legumes on nitrous oxide emissions is still not fully understood. In this study we quantify net GHG fluxes from two differently managed grassland parcels (mitigation, control) and relate our results to productivity (yields). In addition, we aim at revealing the influence of various driver variables on N2O exchange. Our experimental setup consisted of an eddy covariance tower that measured the net exchange of the three major anthropogenic GHGs, nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2). Both grassland parcels can be covered with this tower due to two prevailing wind directions. GHG flux measurements were accompanied by measurements of commonly known driver variables such as water filled pore space, soil temperature, soil oxygen concentrations and mineral N to disentangle the soil meteorological influence of N2O fluxes from human drivers. Following organic fertilizer application, we measured elevated N2O emissions (>1 nmol m-2 s-1) at the control parcel and unchanged N2O emissions at the treatment parcel. Net annual fluxes were 54% and 50% lower at the experimental parcel in 2015 and 2016, respectively. Annual yields did not significantly differ between parcels, but were slightly lower at the experimental parcel compared to the control parcel. Significantly lower nitrous oxide fluxes under experimental management indicate that nitrous oxide emissions can be effectively reduced at very low costs with a clover-based management. Long-term effects on the N budget, implications for the quality of animal feed as well as potential consequences at the farming system level (i.e. manure management) need further evaluation.

Future Automotive Aftertreatment Solutions: The 150°C Challenge Workshop Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zammit, Michael; DiMaggio, Craig L.; Kim, Chang H.

2013-10-15

With future fuel economy standards enacted, the U.S. automotive manufacturers (OEMs) are committed to pursuing a variety of high risk/highly efficient stoichiometric and lean combustion strategies to achieve superior performance. In recognition of this need, the U.S. Department of Energy (DOE) has partnered with domestic automotive manufacturers through U.S. DRIVE to develop these advanced technologies. However, before these advancements can be introduced into the U.S. market, they must also be able to meet increasingly stringent emissions requirements. A significant roadblock to this implementation is the inability of current catalyst and aftertreatment technologies to provide the required activity at the muchmore » lower exhaust temperatures that will accompany highly efficient combustion processes and powertrain strategies. Therefore, the goal of this workshop and report is to create a U.S. DRIVE emission control roadmap that will identify new materials and aftertreatment approaches that offer the potential for 90% conversion of emissions at low temperature (150°C) and are consistent with highly efficient combustion technologies currently under investigation within U.S. DRIVE Advanced Combustion and Emission Control (ACEC) programs.« less

Soil greenhouse gas emissions and carbon budgeting in a short-hydroperiod floodplain wetland

USGS Publications Warehouse

Batson, Jackie; Noe, Gregory B.; Hupp, Cliff R.; Krauss, Ken W.; Rybicki, Nancy B.; Schenk, Edward R.

2015-01-01

Understanding the controls on floodplain carbon (C) cycling is important for assessing greenhouse gas emissions and the potential for C sequestration in river-floodplain ecosystems. We hypothesized that greater hydrologic connectivity would increase C inputs to floodplains that would not only stimulate soil C gas emissions but also sequester more C in soils. In an urban Piedmont river (151 km2 watershed) with a floodplain that is dry most of the year, we quantified soil CO2, CH4, and N2O net emissions along gradients of floodplain hydrologic connectivity, identified controls on soil aerobic and anaerobic respiration, and developed a floodplain soil C budget. Sites were chosen along a longitudinal river gradient and across lateral floodplain geomorphic units (levee, backswamp, and toe slope). CO2 emissions decreased downstream in backswamps and toe slopes and were high on the levees. CH4 and N2O fluxes were near zero; however, CH4emissions were highest in the backswamp. Annual CO2 emissions correlated negatively with soil water-filled pore space and positively with variables related to drier, coarser soil. Conversely, annual CH4 emissions had the opposite pattern of CO2. Spatial variation in aerobic and anaerobic respiration was thus controlled by oxygen availability but was not related to C inputs from sedimentation or vegetation. The annual mean soil CO2 emission rate was 1091 g C m−2 yr−1, the net sedimentation rate was 111 g C m−2 yr−1, and the vegetation production rate was 240 g C m−2 yr−1, with a soil C balance (loss) of −338 g C m−2 yr−1. This floodplain is losing C likely due to long-term drying from watershed urbanization.

Air pollutant emissions from Chinese households: A major and underappreciated ambient pollution source

PubMed Central

Liu, Jun; Mauzerall, Denise L.; Chen, Qi; Zhang, Qiang; Song, Yu; Peng, Wei; Klimont, Zbigniew; Qiu, Xinghua; Zhang, Shiqiu; Hu, Min; Lin, Weili; Smith, Kirk R.; Zhu, Tong

2016-01-01

As part of the 12th Five-Year Plan, the Chinese government has developed air pollution prevention and control plans for key regions with a focus on the power, transport, and industrial sectors. Here, we investigate the contribution of residential emissions to regional air pollution in highly polluted eastern China during the heating season, and find that dramatic improvements in air quality would also result from reduction in residential emissions. We use the Weather Research and Forecasting model coupled with Chemistry to evaluate potential residential emission controls in Beijing and in the Beijing, Tianjin, and Hebei (BTH) region. In January and February 2010, relative to the base case, eliminating residential emissions in Beijing reduced daily average surface PM2.5 (particulate mater with aerodynamic diameter equal or smaller than 2.5 micrometer) concentrations by 14 ± 7 μg⋅m−3 (22 ± 6% of a baseline concentration of 67 ± 41 μg⋅m−3; mean ± SD). Eliminating residential emissions in the BTH region reduced concentrations by 28 ± 19 μg⋅m−3 (40 ± 9% of 67 ± 41 μg⋅m−3), 44 ± 27 μg⋅m−3 (43 ± 10% of 99 ± 54 μg⋅m−3), and 25 ± 14 μg⋅m−3 (35 ± 8% of 70 ± 35 μg⋅m−3) in Beijing, Tianjin, and Hebei provinces, respectively. Annually, elimination of residential sources in the BTH region reduced emissions of primary PM2.5 by 32%, compared with 5%, 6%, and 58% achieved by eliminating emissions from the transportation, power, and industry sectors, respectively. We also find air quality in Beijing would benefit substantially from reductions in residential emissions from regional controls in Tianjin and Hebei, indicating the value of policies at the regional level. PMID:27354524

USER'S GUIDE: EMISSION CONTROL TECHNOLOGIES AND EMISSION FACTORS FOR UNPAVED ROAD FUGITIVE EMISSIONS

EPA Science Inventory

This document assists control agency personnel in evaluating unpaved road fugitive emissions control plans and helps industry personnel develop effective control strategies for unpaved roads. he brochure describes control techniques for reducing unpaved road emissions and methods...

40 CFR 86.1803-01 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

.... Auxiliary Emission Control Device (AECD) means any element of design which senses temperature, vehicle speed.... Critical emission-related components are those components which are designed primarily for emission control... control system is a unique group of emission control devices, auxiliary emission control devices, engine...

Isoprene emission potentials from European oak forests derived from canopy flux measurements: an assessment of uncertainties and inter-algorithm variability

NASA Astrophysics Data System (ADS)

Langford, Ben; Cash, James; Acton, W. Joe F.; Valach, Amy C.; Hewitt, C. Nicholas; Fares, Silvano; Goded, Ignacio; Gruening, Carsten; House, Emily; Kalogridis, Athina-Cerise; Gros, Valérie; Schafers, Richard; Thomas, Rick; Broadmeadow, Mark; Nemitz, Eiko

2017-12-01

Biogenic emission algorithms predict that oak forests account for ˜ 70 % of the total European isoprene budget. Yet the isoprene emission potentials (IEPs) that underpin these model estimates are calculated from a very limited number of leaf-level observations and hence are highly uncertain. Increasingly, micrometeorological techniques such as eddy covariance are used to measure whole-canopy fluxes directly, from which isoprene emission potentials can be calculated. Here, we review five observational datasets of isoprene fluxes from a range of oak forests in the UK, Italy and France. We outline procedures to correct the measured net fluxes for losses from deposition and chemical flux divergence, which were found to be on the order of 5-8 and 4-5 %, respectively. The corrected observational data were used to derive isoprene emission potentials at each site in a two-step process. Firstly, six commonly used emission algorithms were inverted to back out time series of isoprene emission potential, and then an average isoprene emission potential was calculated for each site with an associated uncertainty. We used these data to assess how the derived emission potentials change depending upon the specific emission algorithm used and, importantly, on the particular approach adopted to derive an average site-specific emission potential. Our results show that isoprene emission potentials can vary by up to a factor of 4 depending on the specific algorithm used and whether or not it is used in a big-leaf or canopy environment (CE) model format. When using the same algorithm, the calculated average isoprene emission potential was found to vary by as much as 34 % depending on how the average was derived. Using a consistent approach with version 2.1 of the Model for Emissions of Gases and Aerosols from Nature (MEGAN), we derive new ecosystem-scale isoprene emission potentials for the five measurement sites: Alice Holt, UK (10 500 ± 2500 µg m-2 h-1); Bosco Fontana, Italy (1610 ± 420 µg m-2 h-1); Castelporziano, Italy (121 ± 15 µg m-2 h-1); Ispra, Italy (7590 ± 1070 µg m-2 h-1); and the Observatoire de Haute Provence, France (7990 ± 1010 µg m-2 h-1). Ecosystem-scale isoprene emission potentials were then extrapolated to the leaf-level and compared to previous leaf-level measurements for Quercus robur and Quercus pubescens, two species thought to account for 50 % of the total European isoprene budget. The literature values agreed closely with emission potentials calculated using the G93 algorithm, which were 85 ± 75 and 78 ± 25 µg g-1 h-1 for Q. robur and Q. pubescens, respectively. By contrast, emission potentials calculated using the G06 algorithm, the same algorithm used in a previous study to derive the European budget, were significantly lower, which we attribute to the influence of past light and temperature conditions. Adopting these new G06 specific emission potentials for Q. robur (55 ± 24 µg g-1 h-1) and Q. pubescens (47 ± 16 µg g-1 h-1) reduced the projected European budget by ˜ 17 %. Our findings demonstrate that calculated isoprene emission potentials vary considerably depending upon the specific approach used in their calculation. Therefore, it is our recommendation that the community now adopt a standardised approach to the way in which micrometeorological flux measurements are corrected and used to derive isoprene, and other biogenic volatile organic compounds, emission potentials.

A comprehensive classification method for VOC emission sources to tackle air pollution based on VOC species reactivity and emission amounts.

PubMed

Li, Guohao; Wei, Wei; Shao, Xia; Nie, Lei; Wang, Hailin; Yan, Xiao; Zhang, Rui

2018-05-01

In China, volatile organic compound (VOC) control directives have been continuously released and implemented for important sources and regions to tackle air pollution. The corresponding control requirements were based on VOC emission amounts (EA), but never considered the significant differentiation of VOC species in terms of atmospheric chemical reactivity. This will adversely influence the effect of VOC reduction on air quality improvement. Therefore, this study attempted to develop a comprehensive classification method for typical VOC sources in the Beijing-Tianjin-Hebei region (BTH), by combining the VOC emission amounts with the chemical reactivities of VOC species. Firstly, we obtained the VOC chemical profiles by measuring 5 key sources in the BTH region and referencing another 10 key sources, and estimated the ozone formation potential (OFP) per ton VOC emission for these sources by using the maximum incremental reactivity (MIR) index as the characteristic of source reactivity (SR). Then, we applied the data normalization method to respectively convert EA and SR to normalized EA (NEA) and normalized SR (NSR) for various sources in the BTH region. Finally, the control index (CI) was calculated, and these sources were further classified into four grades based on the normalized CI (NCI). The study results showed that in the BTH region, furniture coating, automobile coating, and road vehicles are characterized by high NCI and need to be given more attention; however, the petro-chemical industry, which was designated as an important control source by air quality managers, has a lower NCI. Copyright © 2017. Published by Elsevier B.V.

Pay attention to non-wastewater emission pathways of pharmaceuticals into environments.

PubMed

Bu, Qingwei; Shi, Xiao; Yu, Gang; Huang, Jun; Wang, Bin; Wang, Jianbing

2016-12-01

Pharmaceuticals have been widely detected in the aquatic environment and demonstrated to be potential risks to humans and the environment. Understanding emission pathways of pharmaceuticals is essential to the control of pharmaceutical contamination for environmental management. The present study is aimed at testing the hypothesis that non-wastewater pathway is also significant to the emission of pharmaceuticals into the environment. To this end, we compared the actual production with the amount of 12 antibiotics obtained by back calculation from sewage concentrations in Beijing, Guangzhou and Chongqing. The results showed that for over a half of investigated antibiotics, the emission through non-wastewater pathways accounted for approximately 30-80% of the total emission, varying with individual antibiotics. It was revealed that non-wastewater emission pathways could be of significance for pharmaceuticals emitted into the environment, of which disposed by household waste could be among the most important non-wastewater pathways. Copyright © 2016 Elsevier Ltd. All rights reserved.

Using shape to turn off blinking for two-colour multiexciton emission in CdSe/CdS tetrapods

NASA Astrophysics Data System (ADS)

Mishra, Nimai; Orfield, Noah J.; Wang, Feng; Hu, Zhongjian; Krishnamurthy, Sachidananda; Malko, Anton V.; Casson, Joanna L.; Htoon, Han; Sykora, Milan; Hollingsworth, Jennifer A.

2017-05-01

Semiconductor nanostructures capable of emitting from two excited states and thereby of producing two photoluminescence colours are of fundamental and potential technological significance. In this limited class of nanocrystals, CdSe/CdS core/arm tetrapods exhibit the unusual trait of two-colour (red and green) multiexcitonic emission, with green emission from the CdS arms emerging only at high excitation fluences. Here we show that by synthetic shape-tuning, both this multi-colour emission process, and blinking and photobleaching behaviours of single tetrapods can be controlled. Specifically, we find that the properties of dual emission and single-nanostructure photostability depend on different structural parameters--arm length and arm diameter, respectively--but that both properties can be realized in the same nanostructure. Furthermore, based on results of correlated photoluminescence and transient absorption measurements, we conclude that hole-trap filling in the arms and partial state-filling in the core are necessary preconditions for the observation of multiexciton multi-colour emission.

Using shape to turn off blinking for two-colour multiexciton emission in CdSe/CdS tetrapods

PubMed Central

Mishra, Nimai; Orfield, Noah J.; Wang, Feng; Hu, Zhongjian; Krishnamurthy, Sachidananda; Malko, Anton V.; Casson, Joanna L.; Htoon, Han; Sykora, Milan; Hollingsworth, Jennifer A.

2017-01-01

Semiconductor nanostructures capable of emitting from two excited states and thereby of producing two photoluminescence colours are of fundamental and potential technological significance. In this limited class of nanocrystals, CdSe/CdS core/arm tetrapods exhibit the unusual trait of two-colour (red and green) multiexcitonic emission, with green emission from the CdS arms emerging only at high excitation fluences. Here we show that by synthetic shape-tuning, both this multi-colour emission process, and blinking and photobleaching behaviours of single tetrapods can be controlled. Specifically, we find that the properties of dual emission and single-nanostructure photostability depend on different structural parameters—arm length and arm diameter, respectively—but that both properties can be realized in the same nanostructure. Furthermore, based on results of correlated photoluminescence and transient absorption measurements, we conclude that hole-trap filling in the arms and partial state-filling in the core are necessary preconditions for the observation of multiexciton multi-colour emission. PMID:28497776

Using shape to turn off blinking for two-colour multiexciton emission in CdSe/CdS tetrapods

DOE PAGES

Mishra, Nimai; Orfield, Noah Jeremiah; Wang, Feng; ...

2017-05-12

Here, semiconductor nanostructures capable of emitting from two excited states and thereby of producing two photoluminescence colours are of fundamental and potential technological significance. In this limited class of nanocrystals, CdSe/CdS core/arm tetrapods exhibit the unusual trait of two-colour (red and green) multiexcitonic emission, with green emission from the CdS arms emerging only at high excitation fluences. Here we show that by synthetic shape-tuning, both this multi-colour emission process, and blinking and photobleaching behaviours of single tetrapods can be controlled. Specifically, we find that the properties of dual emission and single-nanostructure photostability depend on different structural parameters—arm length and armmore » diameter, respectively—but that both properties can be realized in the same nanostructure. Furthermore, based on results of correlated photoluminescence and transient absorption measurements, we conclude that hole-trap filling in the arms and partial state-filling in the core are necessary preconditions for the observation of multiexciton multi-colour emission.« less

Using shape to turn off blinking for two-colour multiexciton emission in CdSe/CdS tetrapods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mishra, Nimai; Orfield, Noah Jeremiah; Wang, Feng

Here, semiconductor nanostructures capable of emitting from two excited states and thereby of producing two photoluminescence colours are of fundamental and potential technological significance. In this limited class of nanocrystals, CdSe/CdS core/arm tetrapods exhibit the unusual trait of two-colour (red and green) multiexcitonic emission, with green emission from the CdS arms emerging only at high excitation fluences. Here we show that by synthetic shape-tuning, both this multi-colour emission process, and blinking and photobleaching behaviours of single tetrapods can be controlled. Specifically, we find that the properties of dual emission and single-nanostructure photostability depend on different structural parameters—arm length and armmore » diameter, respectively—but that both properties can be realized in the same nanostructure. Furthermore, based on results of correlated photoluminescence and transient absorption measurements, we conclude that hole-trap filling in the arms and partial state-filling in the core are necessary preconditions for the observation of multiexciton multi-colour emission.« less

Optical redox ratio differentiates early tissue transformations in DMBA-induced hamster oral carcinogenesis based on autofluorescence spectroscopy coupled with multivariate analysis

NASA Astrophysics Data System (ADS)

Sethupathi, R.; Gurushankar, K.; Krishnakumar, N.

2016-11-01

Fluorescence intensity measurements have the potential to facilitate the diagnoses of many pathological conditions. The changes in fluorescence intensity may be influenced by factors such as tissue architectures, endogenous fluorophores, cellular metabolism and light penetration depth in tissue. Two of the most diagnostically important endogenous fluorophores are reduced nicotinamide dinucleotide (NADH) and flavin adenine dinucleotide (FAD), which can be used to monitor dramatic metabolic changes in cells and tissues. The goal of this study is to investigate changes in the endogenous fluorophore emission and to quantify metabolic changes in the redox state of various tissue transformation conditions with respect to control tissues in dimethyl benz[a] anthracene (DMBA)-induced hamster oral carcinogenesis for measuring emission spectrum at 320 nm excitation. In the present study, collagen, NADH and FAD emission of well-differentiated squamous cell carcinoma (WDSCC) showed decreased intensity at ~385 nm, ~450 nm and ~520 nm compared to hyperplasia, dysplasia and control tissues. Furthermore, a significant decrease in the optical redox ratio is observed in WDSCC tissues, which indicates an increased metabolic activity compared to the control tissues. Moreover, the principal component linear discriminant analysis (PC-LDA) algorithm together with the leave-one-out cross-validation (LOOCV) method yield an overall diagnostic sensitivity of 77.7% and a specificity of 88.8% in the classification of control, hyperplasia, dysplasia and WDSCC tissues, respectively. The results from this study demonstrated that fluorescence-based tissue analysis combined with PC-LDA has tremendous potential for the effective discrimination of control from neoplastic tissues; furthermore it also detects early neoplastic changes prior to definite morphologic alteration.

Exchange pattern of gaseous elemental mercury in landfill: mercury deposition under vegetation coverage and interactive effects of multiple meteorological conditions.

PubMed

Tao, Zhengkai; Liu, Yang; Zhou, Meng; Chai, Xiaoli

2017-12-01

Landfill is known as a potential source of atmospheric Hg and an important component of the local or regional atmospheric Hg budget. This study investigated the gaseous elemental Hg surface-air fluxes under differing conditions at a typical municipal solid waste landfill site, highlighting the interactive effects of plant coverage and meteorological conditions. The results indicated that Hg fluxes exhibited a feature represented by diel variation. In particular, Hg deposition was observed under a condition of Kochia sieversiana coverage, whereas emission that occurred after K. sieversiana was removed. Hg emission was the dominant mode under conditions of Setaria viridis coverage and its removal; however, the average Hg emission flux with the S. viridis coverage was nearly four times lower than after its removal. These findings verified that the plant coverage should be a key factor influencing the Hg emission from landfills. In addition, Hg fluxes were correlated positively with solar radiation and air/soil temperature and correlated inversely with relative humidity under all conditions, except K. sieversiana coverage. This suggested that the interactive effects of meteorological conditions and plant coverage played a jointly significant role in the Hg emission from landfills. It was established that K. sieversiana can inhibit Hg emission efficiently, and therefore, it could potentially be suitable for use as a plant-based method to control Hg pollution from landfills.

Effect of heat waves on VOC emissions from vegetation and urban air quality

NASA Astrophysics Data System (ADS)

Churkina, G.; Kuik, F.; Lauer, A.; Bonn, B.; Butler, T. M.

2015-12-01

Programs to plant millions of trees in cities around the world aim at the reduction of summer temperatures, increase carbon storage, storm water control, provision of space for recreation, as well as poverty alleviation. Although these multiple benefits speak positively for urban greening programs, the programs do not take into account how close human and natural systems are coupled in urban areas. Elevated temperatures together with anthropogenic emissions of air and water pollutants distinguish the urban system. Urban and sub-urban vegetation responds to ambient changes and reacts with pollutants. Neglecting this coupling may lead to unforeseen drawbacks of urban greening programs. The potential for emissions of volatile organic compounds (VOC) from vegetation combined with anthropogenic emissions to produce ozone has long been recognized. This potential increases under rising temperatures. Here we investigate how heat waves affect emissions of VOC from urban vegetation and corresponding ground-level ozone. In this study we use Weather Research and Forecasting Model with coupled atmospheric chemistry (WRF-CHEM) to quantify these feedbacks in Berlin, Germany during the 2006 heat wave. VOC emissions from vegetation are simulated with MEGAN 2.0 coupled with WRF-CHEM. Our preliminary results indicate that contribution of VOCs from vegetation to ozone formation may increase by more than twofold during the heat wave period. We highlight the importance of the vegetation for urban areas under changing climate and discuss associated tradeoffs.

Experimental warming of a mountain tundra increases soil CO2 effluxes and enhances CH4 and N2O uptake at Changbai Mountain, China

PubMed Central

Zhou, Yumei; Hagedorn, Frank; Zhou, Chunliang; Jiang, Xiaojie; Wang, Xiuxiu; Li, Mai-He

2016-01-01

Climatic warming is expected to particularly alter greenhouse gas (GHG) emissions from soils in cold ecosystems such as tundra. We used 1 m2 open-top chambers (OTCs) during three growing seasons to examine how warming (+0.8–1.2 °C) affects the fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) from alpine tundra soils. Results showed that OTC warming increased soil CO2 efflux by 141% in the first growing season and by 45% in the second and third growing season. The mean CH4 flux of the three growing seasons was −27.6 and −16.7 μg CH4-C m−2h−1 in the warmed and control treatment, respectively. Fluxes of N2O switched between net uptake and emission. Warming didn’t significantly affect N2O emission during the first and the second growing season, but stimulated N2O uptake in the third growing season. The global warming potential of GHG was clearly dominated by soil CO2 effluxes (>99%) and was increased by the OTC warming. In conclusion, soil temperature is the main controlling factor for soil respiration in this tundra. Climate warming will lead to higher soil CO2 emissions but also to an enhanced CH4 uptake with an overall increase of the global warming potential for tundra. PMID:26880107

Quantifying Pollutant Emissions from Office Equipment Phase IReport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maddalena, R.L.; Destaillats, H.; Hodgson, A.T.

2006-12-01

Although office equipment has been a focal point for governmental efforts to promote energy efficiency through programs such as Energy Star, little is known about the relationship between office equipment use and indoor air quality. This report provides results of the first phase (Phase I) of a study in which the primary objective is to measure emissions of organic pollutants and particulate matter from a selected set of office equipment typically used in residential and office environments. The specific aims of the overall research effort are: (1) use screening-level measurements to identify and quantify the concentrations of air pollutants ofmore » interest emitted by major categories of distributed office equipment in a controlled environment; (2) quantify the emissions of air pollutants from generally representative, individual machines within each of the major categories in a controlled chamber environment using well defined protocols; (3) characterize the effects of ageing and use on emissions for individual machines spanning several categories; (4) evaluate the importance of operational factors that can be manipulated to reduce pollutant emissions from office machines; and (5) explore the potential relationship between energy consumption and pollutant emissions for machines performing equivalent tasks. The study includes desktop computers (CPU units), computer monitors, and three categories of desktop printing devices. The printer categories are: (1) printers and multipurpose devices using color inkjet technology; (2) low- to medium output printers and multipurpose devices employing monochrome or color laser technology; and (3) high-output monochrome and color laser printers. The literature review and screening level experiments in Phase 1 were designed to identify substances of toxicological significance for more detailed study. In addition, these screening level measurements indicate the potential relative importance of different categories of office equipment with respect to human exposures. The more detailed studies of the next phase of research (Phase II) are meant to characterize changes in emissions with time and may identify factors that can be modified to reduce emissions. These measurements may identify 'win-win' situations in which low energy consumption machines have lower pollutant emissions. This information will be used to compare machines to determine if some are substantially better than their peers with respect to their emissions of pollutants.« less

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

NASA Astrophysics Data System (ADS)

Venterea, R. T.; Baker, J. M.

2009-12-01

Cropped fields in the upper Midwest have the potential to emit relatively large quantities of N2O and NO resulting from soil transformation of N fertilizers applied to crops such as corn and potatoes. The mitigation of N2O emissions may be an effective strategy for offsetting greenhouse gas emissions. While the rate of N fertilizer application exerts some control over N trace gas emission rates, a variety of other management practices and environmental factors interact to regulate these emissions. Observation-based studies are essential for improving models, developing accurate inventories, and documenting offsets. Since 2003, we have been examining the effects of management factors including: tillage, crop rotation, irrigation, and fertilizer chemical form and application method on N2O and NO emissions from corn and potato production systems using chamber-based measurement techniques. A summary of our findings will be presented, including: Application of anhydrous ammonia resulted in twice the N2O emissions compared to urea fertilizer, and twice the NO emissions compared to liquid urea ammonium nitrate (UAN) fertilizer. Growing corn continuously compared to in rotation with soybeans did not alter the amount of N2O emitted during the corn growing season. Reduced tillage (RT), often promoted as a means of reducing carbon losses to the atmosphere, also altered soil N2O emissions. However, the impact of RT on N2O emissions was found to vary, in both magnitude and direction, as a function of N fertilizer management. In addition to these studies, our efforts to overcome some of the inherent limitations of chamber-based flux measurement techniques will be discussed.

40 CFR 75.72 - Determination of NOX mass emissions for common stack and multiple stack configurations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... the affected units as the difference between NOX mass emissions measured in the common stack and NOX... emissions using the maximum potential NOX emission rate, the maximum potential flow rate, and either the maximum potential CO2 concentration or the minimum potential O2 concentration (as applicable). The maximum...

Effects of soil temperature, flooding, and organic matter addition on N2O emissions from a soil of Hongze Lake wetland, China.

PubMed

Lu, Yan; Xu, Hongwen

2014-01-01

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

Enhanced marine sulphur emissions offset global warming and impact rainfall.

PubMed

Grandey, B S; Wang, C

2015-08-21

Artificial fertilisation of the ocean has been proposed as a possible geoengineering method for removing carbon dioxide from the atmosphere. The associated increase in marine primary productivity may lead to an increase in emissions of dimethyl sulphide (DMS), the primary source of sulphate aerosol over remote ocean regions, potentially causing direct and cloud-related indirect aerosol effects on climate. This pathway from ocean fertilisation to aerosol induced cooling of the climate may provide a basis for solar radiation management (SRM) geoengineering. In this study, we investigate the transient climate impacts of two emissions scenarios: an RCP4.5 (Representative Concentration Pathway 4.5) control; and an idealised scenario, based on RCP4.5, in which DMS emissions are substantially enhanced over ocean areas. We use mini-ensembles of a coupled atmosphere-ocean configuration of CESM1(CAM5) (Community Earth System Model version 1, with the Community Atmosphere Model version 5). We find that the cooling effect associated with enhanced DMS emissions beneficially offsets greenhouse gas induced warming across most of the world. However, the rainfall response may adversely affect water resources, potentially impacting human livelihoods. These results demonstrate that changes in marine phytoplankton activity may lead to a mixture of positive and negative impacts on the climate.

Enhanced marine sulphur emissions offset global warming and impact rainfall

PubMed Central

Grandey, B. S.; Wang, C.

2015-01-01

Artificial fertilisation of the ocean has been proposed as a possible geoengineering method for removing carbon dioxide from the atmosphere. The associated increase in marine primary productivity may lead to an increase in emissions of dimethyl sulphide (DMS), the primary source of sulphate aerosol over remote ocean regions, potentially causing direct and cloud-related indirect aerosol effects on climate. This pathway from ocean fertilisation to aerosol induced cooling of the climate may provide a basis for solar radiation management (SRM) geoengineering. In this study, we investigate the transient climate impacts of two emissions scenarios: an RCP4.5 (Representative Concentration Pathway 4.5) control; and an idealised scenario, based on RCP4.5, in which DMS emissions are substantially enhanced over ocean areas. We use mini-ensembles of a coupled atmosphere-ocean configuration of CESM1(CAM5) (Community Earth System Model version 1, with the Community Atmosphere Model version 5). We find that the cooling effect associated with enhanced DMS emissions beneficially offsets greenhouse gas induced warming across most of the world. However, the rainfall response may adversely affect water resources, potentially impacting human livelihoods. These results demonstrate that changes in marine phytoplankton activity may lead to a mixture of positive and negative impacts on the climate. PMID:26293204

Enhanced marine sulphur emissions offset global warming and impact rainfall

NASA Astrophysics Data System (ADS)

Grandey, B. S.; Wang, C.

2015-08-01

Artificial fertilisation of the ocean has been proposed as a possible geoengineering method for removing carbon dioxide from the atmosphere. The associated increase in marine primary productivity may lead to an increase in emissions of dimethyl sulphide (DMS), the primary source of sulphate aerosol over remote ocean regions, potentially causing direct and cloud-related indirect aerosol effects on climate. This pathway from ocean fertilisation to aerosol induced cooling of the climate may provide a basis for solar radiation management (SRM) geoengineering. In this study, we investigate the transient climate impacts of two emissions scenarios: an RCP4.5 (Representative Concentration Pathway 4.5) control; and an idealised scenario, based on RCP4.5, in which DMS emissions are substantially enhanced over ocean areas. We use mini-ensembles of a coupled atmosphere-ocean configuration of CESM1(CAM5) (Community Earth System Model version 1, with the Community Atmosphere Model version 5). We find that the cooling effect associated with enhanced DMS emissions beneficially offsets greenhouse gas induced warming across most of the world. However, the rainfall response may adversely affect water resources, potentially impacting human livelihoods. These results demonstrate that changes in marine phytoplankton activity may lead to a mixture of positive and negative impacts on the climate.

Application of strategies for sanitation management in wastewater treatment plants in order to control/reduce greenhouse gas emissions.

PubMed

Préndez, Margarita; Lara-González, Scarlette

2008-09-01

Greenhouse gases (GHG), basically methane (CH(4)), carbon dioxide (CO(2)) and nitrous oxide (N(2)O), occur at atmospheric concentrations of ppbv to ppmv under natural conditions. GHG have long mean lifetimes and are an important factor for the mean temperature of the Earth. However, increasing anthropogenic emissions could produce a scenario of progressive and cumulative effects over time, causing a potential "global climate change". Biological degradation of the organic matter present in wastewater is considered one of the anthropogenic sources of GHG. In this study, GHG emissions for the period 1990-2027 were estimated considering the sanitation process and the official domestic wastewater treatment startup schedule approved for the Metropolitan Region (MR) of Santiago, Chile. The methodology considers selected models proposed by the Intergovernmental Panel on Climate Change (IPCC) and some others published by different authors; these were modified according to national conditions and different sanitation and temporal scenarios. For the end of the modeled period (2027), results show emissions of about 65 Tg CO(2) equiv./year (as global warming potential), which represent around 50% of national emissions. These values could be reduced if certain sanitation management strategies were introduced in the environmental management by the sanitation company in charge of wastewater treatment.

Temporal Collinearity Amongst Modeled and Measured Pollutant Concentrations and Meteorology

EPA Science Inventory

The results from epidemiology time series models that relate air quality to human health are often used in determining the need for emission controls in the United States. These epidemiology models, however, can be sensitive to collinearity among co-variates, potentially magnify...

EVALUATION OF CONTROL STRATEGIES FOR VOLATILE ORGANIC COMPOUND IN INDOOR AIR

EPA Science Inventory

The Air and Energy Engineering Research Laboratory of the U.S. Environmental Protection Agency (U.S. EPA) conducts and sponsors research on technology to reduce or eliminate emissions of potentially toxic volatile organic compounds (VOCs) from industrial/commercial sources. The r...

Spacecraft potential control on ISEE-1

NASA Technical Reports Server (NTRS)

Gonfalone, A.; Pedersen, A.; Fahleson, U. V.; Faelthammar, C. G.; Mozer, F. S.; Torbert, R. B.

1979-01-01

Active control of the potential of the ISEE-1 satellite by the use of electron guns is reviewed. The electron guns contain a special cathode capable of emitting an electron current selectable between 10 to the -8th power and 10 to the -3rd power at energies from approximately .6 to 41 eV. Results obtained during flight show that the satellite potential can be stabilized at a value more positive than the normally positive floating potential. The electron guns also reduce the spin modulation of the spacecraft potential which is due to the aspect dependent photoemission of the long booms. Plasma parameters like electron temperature and density can be deduced from the variation of the spacecraft potential as a function of the gun current. The effects of electron beam emission on other experiments are briefly mentioned.

Nitrous Oxide Emissions Affected by Biochar and Nitrogen Stabilizers

NASA Astrophysics Data System (ADS)

Gao, S.; Cai, Z.; Xu, M.

2016-12-01

Both biochar and N fertilizer stabilizers (N transformation inhibitors) are potential strategies to reduce nitrous oxide (N2O) emissions from fertilization, but the mechanisms and/or N transformation processes affecting the N dynamics are not fully understood. This research investigated N2O emissions and N transformations in soil amended with biochar and N transformation inhibitors. The soil was a sandy loam soil and adjusted to 10% soil water content and incubated at 25oC. Biochar amendment at 1% (w/w), Agrotain® Ultra (urease inhibitor), Agrotain® Plus (urease and nitrification inhibitor), and N-Serve® 24 (nitrification inhibitor) as well as another potential nitrification inhibitor, potassium thiosulfate (KTS), at 0.25-1:1 K2O/N ratios (w/w) were tested. Emissions of N2O, soil mineral N species change, and soil pH were determined for 35 days after fertilizers were applied. Biochar, Agrotain® Ultra or Plus, or N-Serve® 24 all effectively reduced N2O emissions by more than 60% as compared to no amendment control. The KTS, however, was only effective in reducing N2O emissions at a high ratio (1:1 K2O/N, w/w). There was a strong correlation between N2O emission and the concentration of nitrite (NO2-) in soil but not other mineral species. All the amendments showed that their effects on N transformation and N2O emissions were completed within a few weeks after application. Laboratory analysis indicated that biochar affected the N dynamics most likely via adsorption of ammonium (NH4+) and the inhibitors by affecting N transformation rate. This research has gained further understanding on how biochar and N stabilizers affect N2O emissions and the knowledge can assist in developing mitigation strategies.

Understanding workers' exposure: Systematic review and data-analysis of emission potential for NOAA.

PubMed

Kuijpers, E; Bekker, C; Brouwer, D; le Feber, M; Fransman, W

2017-05-01

Exposure assessment for nano-objects, and their aggregates and agglomerates (NOAA), has evolved from explorative research toward more comprehensive exposure assessment, providing data to further develop currently used conservative control banding (CB) tools for risk assessment. This study aims to provide an overview of current knowledge on emission potential of NOAA across the occupational life cycle stages by a systematic review and subsequently use the results in a data analysis. Relevant parameters that influence emission were collected from peer-reviewed literature with a focus on the four source domains (SD) in the source-receptor conceptual framework for NOAA. To make the reviewed exposure data comparable, we applied an approach to normalize for workplace circumstances and measurement location, resulting in comparable "surrogate" emission levels. Finally, descriptive statistics were performed. During the synthesis of nanoparticles (SD1), mechanical reduction and gas phase synthesis resulted in the highest emission compared to wet chemistry and chemical vapor condensation. For the handling and transfer of bulk manufactured nanomaterial powders (SD2) the emission could be differentiated for five activity classes: (1) harvesting; (2) dumping; (3); mixing; (4) cleaning of a reactor; and (5) transferring. Additionally, SD2 was subdivided by the handled amount with cleaning further subdivided by energy level. Harvesting and dumping resulted in the highest emissions. Regarding processes with liquids (SD3b), it was possible to distinguish emissions for spraying (propellant gas, (high) pressure and pump), sonication and brushing/rolling. The highest emissions observed in SD3b were for propellant gas spraying and pressure spraying. The highest emissions for the handling of nano-articles (SD4) were found to nano-sized particles (including NOAA) for grinding. This study provides a valuable overview of emission assessments performed in the workplace during the occupational handling of NOAA. Analyses were made per source domain to derive emission levels which can be used for models to quantitatively predict the exposure.

Effects of agriculture upon the air quality and climate: research, policy, and regulations.

PubMed

Aneja, Viney P; Schlesinger, William H; Erisman, Jan Willem

2009-06-15

Scientific assessments of agricultural air quality, including estimates of emissions and potential sequestration of greenhouse gases, are an important emerging area of environmental science that offers significant challenges to policy and regulatory authorities. Improvements are needed in measurements, modeling, emission controls, and farm operation management. Controlling emissions of gases and particulate matter from agriculture is notoriously difficult as this sector affects the most basic need of humans, i.e., food. Current policies combine an inadequate science covering a very disparate range of activities in a complex industry with social and political overlays. Moreover, agricultural emissions derive from both area and point sources. In the United States, agricultural emissions play an important role in several atmospherically mediated processes of environmental and public health concerns. These atmospheric processes affect local and regional environmental quality, including odor, particulate matter (PM) exposure, eutrophication, acidification, exposure to toxics, climate, and pathogens. Agricultural emissions also contribute to the global problems caused by greenhouse gas emissions. Agricultural emissions are variable in space and time and in how they interact within the various processes and media affected. Most important in the U.S. are ammonia (where agriculture accounts for approximately 90% of total emissions), reduced sulfur (unquantified), PM25 (approximately 16%), PM110 (approximately 18%), methane (approximately 29%), nitrous oxide (approximately 72%), and odor and emissions of pathogens (both unquantified). Agriculture also consumes fossil fuels for fertilizer production and farm operations, thus emitting carbon dioxide (CO2), oxides of nitrogen (NO(x)), sulfur oxides (SO(x)), and particulates. Current research priorities include the quantification of point and nonpoint sources, the biosphere-atmosphere exchange of ammonia, reduced sulfur compounds, volatile organic compounds, greenhouse gases, odor and pathogens, the quantification of landscape processes, and the primary and secondary emissions of PM. Given the serious concerns raised regarding the amount and the impacts of agricultural air emissions, policies must be pursued and regulations must be enacted in orderto make real progress in reducing these emissions and their associated environmental impacts.

Sensor-based demand controlled ventilation

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Almeida, A.T.; Fisk, W.J.

In most buildings, occupancy and indoor pollutant emission rates vary with time. With sensor-based demand-controlled ventilation (SBDCV), the rate of ventilation (i.e., rate of outside air supply) also varies with time to compensate for the changes in pollutant generation. In other words, SBDCV involves the application of sensing, feedback and control to modulate ventilation. Compared to ventilation without feedback, SBDCV offers two potential advantages: (1) better control of indoor pollutant concentrations; and (2) lower energy use and peak energy demand. SBDCV has the potential to improve indoor air quality by increasing the rate of ventilation when indoor pollutant generation ratesmore » are high and occupants are present. SBDCV can also save energy by decreasing the rate of ventilation when indoor pollutant generation rates are low or occupants are absent. After providing background information on indoor air quality and ventilation, this report provides a relatively comprehensive discussion of SBDCV. Topics covered in the report include basic principles of SBDCV, sensor technologies, technologies for controlling air flow rates, case studies of SBDCV, application of SBDCV to laboratory buildings, and research needs. SBDCV appears to be an increasingly attractive technology option. Based on the review of literature and theoretical considerations, the application of SBDCV has the potential to be cost-effective in applications with the following characteristics: (a) a single or small number of dominant pollutants, so that ventilation sufficient to control the concentration of the dominant pollutants provides effective control of all other pollutants; (b) large buildings or rooms with unpredictable temporally variable occupancy or pollutant emission; and (c) climates with high heating or cooling loads or locations with expensive energy.« less

Spatially Refined Aerosol Direct Radiative Forcing Efficiencies

NASA Technical Reports Server (NTRS)

Henze, Daven K.; Shindell, Drew Todd; Akhtar, Farhan; Spurr, Robert J. D.; Pinder, Robert W.; Loughlin, Dan; Kopacz, Monika; Singh, Kumaresh; Shim, Changsub

2012-01-01

Global aerosol direct radiative forcing (DRF) is an important metric for assessing potential climate impacts of future emissions changes. However, the radiative consequences of emissions perturbations are not readily quantified nor well understood at the level of detail necessary to assess realistic policy options. To address this challenge, here we show how adjoint model sensitivities can be used to provide highly spatially resolved estimates of the DRF from emissions of black carbon (BC), primary organic carbon (OC), sulfur dioxide (SO2), and ammonia (NH3), using the example of emissions from each sector and country following multiple Representative Concentration Pathway (RCPs). The radiative forcing efficiencies of many individual emissions are found to differ considerably from regional or sectoral averages for NH3, SO2 from the power sector, and BC from domestic, industrial, transportation and biomass burning sources. Consequently, the amount of emissions controls required to attain a specific DRF varies at intracontinental scales by up to a factor of 4. These results thus demonstrate both a need and means for incorporating spatially refined aerosol DRF into analysis of future emissions scenario and design of air quality and climate change mitigation policies.

Impact of hydrochar on rice paddy CH4 and N2O emissions: A comparative study with pyrochar.

PubMed

Zhou, Beibei; Feng, Yanfang; Wang, Yueman; Yang, Linzhang; Xue, Lihong; Xing, Baoshan

2018-08-01

Hydrothermal carbonization (HTC) thermally converts wet biomasses to carbon materials, dramatically reducing energy use for drying and improving solid product yield compared to pyrolysis process. However, researches regarding agricultural usage of hydrochar (HC) are limited. In the present study, the influence of HC amendment on CH 4 and N 2 O emissions, as well as global warming potential (GWP) and greenhouse gas intensity (GHGI) were investigated. Additionally, pyrochar (PC) treatments as well as two char-free control treatments with (CKU) or without (CK) N fertilizer were also included for comparison. Chars were produced from wheat straw (WC) and saw dust (SC) and applied at different rates (0.5% and 3%, w/w). Both hydrochar and pyrochar decreased paddy CH 4 emissions when amended at a lower rate (0.5%) compared to CKU treatment, which was more obvious for pyrochar when applied at the rate of 3%. Contrarily, 3%-HC significantly stimulated CH 4 emissions, which were around 5 and 3 times higher than that of CKU for WC and SC, respectively. Furthermore, hydrochar showed the potential to decrease paddy N 2 O emissions (6.06-32.32%) at both application rates. However, N 2 O emissions with PC treatments varied depending on application rate (20.20-75.76%). GWP and GHGI values of 0.5%-HC and PC treatments were similar, 6.67-25.00% and 3.85-25.00% lower than those of CKU treatment, respectively. However, 3%-HC amendments led to significantly increased GWP and GHGI. This study suggested that application rate of hydrochar used in rice fields should be taken into serious consideration to fulfill its potential in GHGs mitigation and minimize environmental side effects. Copyright © 2018 Elsevier Ltd. All rights reserved.

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.

Evaluation of emission control strategies to reduce ozone pollution in the Paso del Norte region using a photochemical air quality modeling system

NASA Astrophysics Data System (ADS)

Valenzuela, Victor Hugo

Air pollution emissions control strategies to reduce ozone precursor pollutants are analyzed by applying a photochemical modeling system. Simulations of air quality conditions during an ozone episode which occurred in June, 2006 are undertaken by increasing or reducing area source emissions in Ciudad Juarez, Chihuahua, Mexico. Two air pollutants are primary drivers in the formation of tropospheric ozone. Oxides of nitrogen (NOx) and volatile organic compounds (VOC) undergo multiple chemical reactions under favorable meteorological conditions to form ozone, which is a secondary pollutant that irritates respiratory systems in sensitive individuals especially the elderly and young children. The U.S. Environmental Protection Agency established National Ambient Air Quality Standards (NAAQS) to limit ambient air pollutants such as ozone by establishing an 8-hour average concentration of 0.075 ppm as the threshold at which a violation of the standard occurs. Ozone forms primarily due reactions in the troposphere of NOx and VOC emissions generated primarily by anthropogenic sources in urban regions. Data from emissions inventories indicate area sources account for ˜15 of NOx and ˜45% of regional VOC emissions. Area sources include gasoline stations, automotive paint bodyshops and nonroad mobile sources. Multiplicity of air pollution emissions sources provides an opportunity to investigate and potentially implement air quality improvement strategies to reduce emissions which contribute to elevated ozone concentrations. A baseline modeling scenario was established using the CAMx photochemical air quality model from which a series of sensitivity analyses for evaluating air quality control strategies were conducted. Modifications to area source emissions were made by varying NOx and / or VOC emissions in the areas of particular interest. Model performance was assessed for each sensitivity analysis. Normalized bias (NB) and normalized error (NE) were used to identify variability of the PREDICTED to OBSERVED ozone concentrations of both BASELINE model and simulations with modified emissions assessed by the sensitivity analysis. All simulations were found to vary within acceptable ranges of these two criteria variables. Simulation results indicate ozone formation in the PdN region is VOC-limited. Under VOC-limited conditions, modifications to NOx emissions do not produce a marked increase or decrease in ozone concentrations. Modifications to VOC emissions generated the highest variability in ozone concentrations. Increasing VOC emissions by 75% produced results which minimized model bias and error when comparing PREDICTED and OBSERVED ozone concentrations. Increasing VOC emissions by 75% either alone or in combination with a 75% increase in NOx emissions generated PREDICTED ozone concentrations very near to OBSERVED ozone. By evaluating the changes in ambient ozone concentrations through photochemical modeling, air quality planners may identify the most efficient or effective VOC emissions control strategies for area sources. Among the strategies to achieve emissions reductions are installation of gasoline vapor recovery systems, replacing high-pressure low-volume surface coating paint spray guns with high-volume low-pressure spray paint guns, requiring emissions control booths for surface coating operations as well as undertaking solvent management practices, requiring the sale of low VOC paint solvents in the surface-coating industry, and requiring low-VOC solvents in the dry cleaning industry. Other strategies to reduce VOC emissions include initiating Eco-Driving strategies to reduce fuel consumption from mobile sources and minimize vehicle idling at the international ports of entry by reducing bridge wait times. This dissertation depicts a tool for evaluating impacts of emissions on regional air quality by addressing the highly unresolved fugitive emissions in the Paso del Norte region. It provides a protocol for decision makers to assess the effects of various emission control strategies in the region. Impacts of specific source categories such as the international ports of entry, gasoline stations, paint body shops, truck stops, and military installations on the regional air quality can be easily and systematically addressed in a timely manner in the future.

Emission color-tuned light-emitting diode microarrays of nonpolar In xGa 1–xN/GaN multishell nanotube heterostructures

DOE PAGES

Hong, Young Joon; Lee, Chul -Ho; Yoo, Jinkyoung; ...

2015-12-09

Integration of nanostructure lighting source arrays with well-defined emission wavelengths is of great importance for optoelectronic integrated monolithic circuitry. We report on the fabrication and optical properties of GaN-based p–n junction multishell nanotube microarrays with composition-modulated nonpolar m-plane In xGa 1–xN/GaN multiple quantum wells (MQWs) integrated on c-sapphire or Si substrates. The emission wavelengths were controlled in the visible spectral range of green to violet by varying the indium mole fraction of the In xGa 1–xN MQWs in the range 0.13 ≤ x ≤ 0.36. Homogeneous emission from the entire area of the nanotube LED arrays was achieved via themore » formation of MQWs with uniform QW widths and composition by heteroepitaxy on the well-ordered nanotube arrays. Importantly, the wavelength-invariant electroluminescence emission was observed above a turn-on of 3.0 V because both the quantum-confinement Stark effect and band filling were suppressed due to the lack of spontaneous inherent electric field in the m-plane nanotube nonpolar MQWs. Lastly, the method of fabricating the multishell nanotube LED microarrays with controlled emission colors has potential applications in monolithic nonpolar photonic and optoelectronic devices on commonly used c-sapphire and Si substrates.« less

40 CFR 60.1935 - What equations must I use?

Code of Federal Regulations, 2011 CFR

2011-07-01

...) Percent reduction in potential hydrogen chloride emissions. Calculate the percent reduction in potential hydrogen chloride emissions (%PHC1) using equation 3 of this section: ER06DE00.005 Where: %PHC1 = percent reduction of the potential hydrogen chloride emissions Ei = hydrogen chloride emission concentration as...

40 CFR 60.1935 - What equations must I use?

Code of Federal Regulations, 2010 CFR

2010-07-01

...) Percent reduction in potential hydrogen chloride emissions. Calculate the percent reduction in potential hydrogen chloride emissions (%PHC1) using equation 3 of this section: ER06DE00.005 Where: %PHC1 = percent reduction of the potential hydrogen chloride emissions Ei = hydrogen chloride emission concentration as...

Physical and biological controls over patterns of methane flux from wetland soils

NASA Astrophysics Data System (ADS)

Owens, S. M.; von Fischer, J. C.

2006-12-01

While methane (CH4) production and plant-facilitated gas transport both contribute to patterns of CH4 emissions from wetlands, the relative importance of each mechanism is uncertain. In flooded wetland soils, CH4 is produced by anaerobic methanogenic bacteria. In the absence of competing oxidizers (i.e. SO42-, NO3-, O2), CH4 production is limited by the availability of labile carbon, which is supplied from recent plant primary production (e.g. as root exudates) and converted by anaerobic fermenting bacteria into methanogenic substrate (e.g. acetate). Because diffusion of gases through saturated soils is extremely slow, the aerenchymous tissues of wetland plants provide the primary pathway for CH4 emissions in systems dominated by emergent vascular vegetation. Aerenchyma also function to shuttle atmospheric oxygen to belowground plant tissues for respiration. Consequentially, root radial oxygen loss results in an oxidized rhizosphere, which limits CH4 production and provides habitat for aerobic methanotrophic bacteria, potentially reducing CH4 emissions. To test the contribution of recent photosynthates on CH4 emissions, a shading experiment was conducted in a Juncus-dominated wetland in the Colorado Front Range. Shade treatments significantly reduced net ecosystem production (NEE) and gross primary production (GPP) compared to control plots (p=0.0194 and p=0.0551, respectively). While CH4 emissions did not significantly differ between treatments, CH4 flux rates were strongly correlated with NEE (p=0.0063) and GPP (p=0.0020), in support of the hypothesis that labile carbon from recent photosynthesis controls patterns of CH4 emissions. The relative importance of plant gas transport and methane consumption rates on CH4 emissions is not known. Methane flux is more tightly correlated with NEE than GPP, which may be explained by increased CH4 consumption or decreased CH4 production as a result of rhizospheric oxidation. The ability to predict future emissions of this important greenhouse gas will be improved by increased understanding of the controls regulating its emission. Future work will focus on developing a tracer technique using SF6 and 13C-labeled CH4 to determine how plant gas transport properties and CH4 consumption contribute to patterns of methane emissions from wetlands.

Radiated Emissions from a Remote-Controlled Airplane-Measured in a Reverberation Chamber

NASA Technical Reports Server (NTRS)

Ely, Jay J.; Koppen, Sandra V.; Nguyen, Truong X.; Dudley, Kenneth L.; Szatkowski, George N.; Quach, Cuong C.; Vazquez, Sixto L.; Mielnik, John J.; Hogge, Edward F.; Hill, Boyd L.;

Analysis of differential and active charging phenomena on ATS-5 and ATS-6

NASA Technical Reports Server (NTRS)

Olsen, R. C.; Whipple, E. C., Jr.

1980-01-01

Spacecraft charging on the differential charging and artificial particle emission experiments on ATS 5 and ATS 6 were studied. Differential charging of spacecraft surfaces generated large electrostatic barriers to spacecraft generated electrons, from photoemission, secondary emission, and thermal emitters. The electron emitter could partially or totally discharge the satellite, but the mainframe recharged negatively in a few 10's of seconds. The time dependence of the charging behavior was explained by the relatively large capacitance for differential charging in comparison to the small spacecraft to space capacitance. A daylight charging event on ATS 6 was shown to have a charging behavior suggesting the dominance of differential charging on the absolute potential of the mainframe. Ion engine operations and plasma emission experiments on ATS 6 were shown to be an effective means of controlling the spacecraft potential in eclipse and sunlight. Elimination of barrier effects around the detectors and improving the quality of the particle data are discussed.

Relationship between leukemia incidence and residing and/or working near the Pilgrim 1 nuclear power plant in Plymouth, Massachusetts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morris, M.S.

1992-01-01

To determine whether a strong association between leukemia incidence between 1978 and 1986 and potential for exposure to radiation emitted from the Pilgrim 1 nuclear power plant in Plymouth, Massachusetts was a spurious finding resulting from either (1) failure to account for temporal variation in the level of radioactivity released from the plant or (2) inattention to certain potentially confounding factors, additional age/sex-matched case-control analyses controlled for the effects of socioeconomic status (SES), work history, and cigarette smoking were performed with data collected in the Southeastern Massachusetts Health Investigation -- a study of leukemia among residents aged 13 and oldermore » of 22 southeastern Massachusetts towns. None of the additional analyses, including incorporation of emissions data into the exposure-assessment scheme and crude attempts to control for (1) medical-radiation exposure, (2) potential for exposure to pesticides sprayed on cranberry bogs, or (3) workplace exposure to radiation, chemical solvents, dust, or fumes, altered the finding of a statistically significant dose-response relationship between leukemia incidence and potential for exposure to radioactive emissions. The trend in the association over time was not entirely consistent, however, with the hypothesis that unusually large amounts of radioactivity reportedly released from the plant during the mid-1970s were responsible for the observed effects. Recommendations were made for further study of the Plymouth-area population for studies of this problem elsewhere.« less

Anomalous CO2 Emissions in Different Ecosystems Around the World

NASA Astrophysics Data System (ADS)

Sanchez-Canete, E. P.; Moya Jiménez, M. R.; Kowalski, A. S.; Serrano-Ortiz, P.; López-Ballesteros, A.; Oyonarte, C.; Domingo, F.

2016-12-01

As an important tool for understanding and monitoring ecosystem dynamics at ecosystem level, the eddy covariance (EC) technique allows the assessment of the diurnal and seasonal variation of the net ecosystem exchange (NEE). Despite the high temporal resolution data available, there are still many processes (in addition to photosynthesis and respiration) that, although they are being monitored, have been neglected. Only a few authors have studied anomalous CO2 emissions (non biological), and have related them to soil ventilation, photodegradation or geochemical processes. The aim of this study is: 1) to identify anomalous short term CO2 emissions in different ecosystems distributed around the world, 2) to determine the meteorological variables that are influencing these emissions, and 3) to explore the potential processes that can be involved. We have studied EC data together with other meteorological ancillary variables obtained from the FLUXNET database (version 2015) and have found more than 50 sites with anomalous CO2 emissions in different ecosystem types such as grasslands, croplands or savannas. Data were filtered according to the FLUXNET quality control flags (only data with quality control flag equal to 0 was used) and correlation analysis were performed with NEE and ancillary data. Preliminary results showed strong and highly significant correlations between meteorological variables and anomalous CO2 emissions. Correlation results showed clear differing behaviors between ecosystems types, which could be related to the different processes involved in the anomalous CO2 emissions. We suggest that anomalous CO2 emissions are happening globally and therefore, their contribution to the global net ecosystem carbon balance requires further investigation in order to better understand its drivers.

Observations and modeling of air quality trends over 1990-2010 across the Northern Hemisphere: China, the United States and Europe

NASA Astrophysics Data System (ADS)

Xing, J.; Mathur, R.; Pleim, J.; Hogrefe, C.; Gan, C.-M.; Wong, D. C.; Wei, C.; Gilliam, R.; Pouliot, G.

2015-03-01

Trends in air quality across the Northern Hemisphere over a 21-year period (1990-2010) were simulated using the Community Multiscale Air Quality (CMAQ) multiscale chemical transport model driven by meteorology from Weather Research and Forecasting (WRF) simulations and internally consistent historical emission inventories obtained from EDGAR. Thorough comparison with several ground observation networks mostly over Europe and North America was conducted to evaluate the model performance as well as the ability of CMAQ to reproduce the observed trends in air quality over the past 2 decades in three regions: eastern China, the continental United States and Europe. The model successfully reproduced the observed decreasing trends in SO2, NO2, 8 h O3 maxima, SO42- and elemental carbon (EC) in the US and Europe. However, the model fails to reproduce the decreasing trends in NO3- in the US, potentially pointing to uncertainties of NH3 emissions. The model failed to capture the 6-year trends of SO2 and NO2 in CN-API (China - Air Pollution Index) from 2005 to 2010, but reproduced the observed pattern of O3 trends shown in three World Data Centre for Greenhouse Gases (WDCGG) sites over eastern Asia. Due to the coarse spatial resolution employed in these calculations, predicted SO2 and NO2 concentrations are underestimated relative to all urban networks, i.e., US-AQS (US - Air Quality System; normalized mean bias (NMB) = -38% and -48%), EU-AIRBASE (European Air quality data Base; NMB = -18 and -54%) and CN-API (NMB = -36 and -68%). Conversely, at the rural network EU-EMEP (European Monitoring and Evaluation Programme), SO2 is overestimated (NMB from 4 to 150%) while NO2 is simulated well (NMB within ±15%) in all seasons. Correlations between simulated and observed O3 wintertime daily 8 h maxima (DM8) are poor compared to other seasons for all networks. Better correlation between simulated and observed SO42- was found compared to that for SO2. Underestimation of summer SO42- in the US may be associated with the uncertainty in precipitation and associated wet scavenging representation in the model. The model exhibits worse performance for NO3- predictions, particularly in summer, due to high uncertainties in the gas/particle partitioning of NO3- as well as seasonal variations of NH3 emissions. There are high correlations (R > 0.5) between observed and simulated EC, although the model underestimates the EC concentration by 65% due to the coarse grid resolution as well as uncertainties in the PM speciation profile associated with EC emissions. The almost linear response seen in the trajectory of modeled O3 changes in eastern China over the past 2 decades suggests that control strategies that focus on combined control of NOx and volatile organic compound (VOC) emissions with a ratio of 0.46 may provide the most effective means for O3 reductions for the region devoid of nonlinear response potentially associated with NOx or VOC limitation resulting from alternate strategies. The response of O3 is more sensitive to changes in NOx emissions in the eastern US because the relative abundance of biogenic VOC emissions tends to reduce the effectiveness of VOC controls. Increasing NH3 levels offset the relative effectiveness of NOx controls in reducing the relative fraction of aerosol NO3- formed from declining NOx emissions in the eastern US, while the control effectiveness was assured by the simultaneous control of NH3 emission in Europe.

The influence of microbial-based inoculants on N2O emissions from soil planted with corn (Zea mays L.) under greenhouse conditions with different nitrogen fertilizer regimens.

PubMed

Calvo, Pamela; Watts, Dexter B; Kloepper, Joseph W; Torbert, H Allen

2016-12-01

Nitrous oxide (N 2 O) emissions are increasing at an unprecedented rate owing to the increased use of nitrogen (N) fertilizers. Thus, new innovative management tools are needed to reduce emissions. One potential approach is the use of microbial inoculants in agricultural production. In a previous incubation study, we observed reductions in N 2 O emissions when microbial-based inoculants were added to soil (no plants present) with N fertilizers under laboratory incubations. This present study evaluated the effects of microbial-based inoculants on N 2 O and carbon dioxide (CO 2 ) emissions when applied to soil planted with corn (Zea mays L.) under controlled greenhouse conditions. Inoculant treatments consisted of (i) SoilBuilder (SB), (ii) a metabolite extract of SoilBuilder (SBF), and (iii) a mixture of 4 strains of plant-growth-promoting Bacillus spp. (BM). Experiments included an unfertilized control and 3 N fertilizers: urea, urea - ammonium nitrate with 32% N (UAN-32), and calcium - ammonium nitrate with 17% N (CAN-17). Cumulative N 2 O fluxes from pots 41 days after planting showed significant reductions in N 2 O of 15% (SB), 41% (BM), and 28% (SBF) with CAN-17 fertilizer. When UAN-32 was used, reductions of 34% (SB), 35% (SBF), and 49% (BM) were obtained. However, no reductions in N 2 O emissions occurred with urea. Microbial-based inoculants did not affect total CO 2 emissions from any of the fertilized treatments or the unfertilized control. N uptake was increased by an average of 56% with microbial inoculants compared with the control (nonmicrobial-based treatments). Significant increases in plant height, SPAD chlorophyll readings, and fresh and dry shoot mass were also observed when the microbial-based treatments were applied (with and without N). Overall, results demonstrate that microbial inoculants can reduce N 2 O emissions following fertilizer application depending on the N fertilizer type used and can enhance N uptake and plant growth. Future studies are planned to evaluate the effectiveness of these microbial inoculants in field-based trials and determine the mechanisms involved in N 2 O reduction.

Evaluating landfill aftercare strategies: A life cycle assessment approach.

PubMed

Turner, David A; Beaven, Richard P; Woodman, Nick D

2017-05-01

This study investigates the potential impacts caused by the loss of active environmental control measures during the aftercare period of landfill management. A combined mechanistic solute flow model and life cycle assessment (LCA) approach was used to evaluate the potential impacts of leachate emissions over a 10,000year time horizon. A continuum of control loss possibilities occurring at different times and for different durations were investigated for four different basic aftercare scenarios, including a typical aftercare scenario involving a low permeability cap and three accelerated aftercare scenarios involving higher initial infiltration rates. Assuming a 'best case' where control is never lost, the largest potential impacts resulted from the typical aftercare scenario. The maximum difference between potential impacts from the 'best case' and the 'worst case', where control fails at the earliest possible point and is never reinstated, was only a fourfold increase. This highlights potential deficiencies in standard life cycle impact assessment practice, which are discussed. Nevertheless, the results show how the influence of active control loss on the potential impacts of landfilling varies considerably depending on the aftercare strategy used and highlight the importance that leachate treatment efficiencies have upon impacts. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Ferrofluids Story

NASA Technical Reports Server (NTRS)

1993-01-01

A new Ferrofluidics exclusion seal promises improvement in controlling "fugitive emissions" -vapors that escape into the atmosphere from petroleum refining and chemical processing facilities. These are primarily volatile organic compounds, and their emissions are highly regulated by the EPA. The ferrofluid system consists of a primary mechanical seal working in tandem with a secondary seal. Ferrofluids are magnetic liquids - fluids in which microscopic metal particles have been suspended, allowing the liquid to be controlled by a magnetic force. The concept was developed in the early years of the Space program, but never used. Two Avco scientists, however, saw commercial potential in ferrofluids and formed a company. Among exclusion seal commercial applications are rotary feedthrough seals, hydrodynamic bearings and fluids for home and automotive loudspeakers. Ferrofluidics has subsidiaries throughout the world.

Reducing cyclone pressure drop with evasés

USDA-ARS?s Scientific Manuscript database

Cyclones are widely used to separate particles from gas flows and as air emissions control devices. Their cost of operation is proportional to the fan energy required to overcome their pressure drop. Evasés or exit diffusers potentially could reduce exit pressure losses without affecting collection...

Photochemical Conversion of Surrogate Emissions for Use in Toxicological Studies: Role of Particulate- and Gas-Phase Products

EPA Science Inventory

The production of photochemical atmospheres under controlled conditions in an irradiated chamber permits the manipulation of a variety of parameters that influences resulting air pollutant chemistry and potential biological effects. To date no studies have examined how contrastin...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, Young Joon; Lee, Chul -Ho; Yoo, Jinkyoung

Integration of nanostructure lighting source arrays with well-defined emission wavelengths is of great importance for optoelectronic integrated monolithic circuitry. We report on the fabrication and optical properties of GaN-based p–n junction multishell nanotube microarrays with composition-modulated nonpolar m-plane In xGa 1–xN/GaN multiple quantum wells (MQWs) integrated on c-sapphire or Si substrates. The emission wavelengths were controlled in the visible spectral range of green to violet by varying the indium mole fraction of the In xGa 1–xN MQWs in the range 0.13 ≤ x ≤ 0.36. Homogeneous emission from the entire area of the nanotube LED arrays was achieved via themore » formation of MQWs with uniform QW widths and composition by heteroepitaxy on the well-ordered nanotube arrays. Importantly, the wavelength-invariant electroluminescence emission was observed above a turn-on of 3.0 V because both the quantum-confinement Stark effect and band filling were suppressed due to the lack of spontaneous inherent electric field in the m-plane nanotube nonpolar MQWs. Lastly, the method of fabricating the multishell nanotube LED microarrays with controlled emission colors has potential applications in monolithic nonpolar photonic and optoelectronic devices on commonly used c-sapphire and Si substrates.« less

Study on feasible technical potential of coal to electricity in china

NASA Astrophysics Data System (ADS)

Jia, Dexiang; Tan, Xiandong

2017-01-01

The control of bulk coal is one of the important work of air pollution control in China’s future. Existing research mainly focuses on the adaptability, economy, construction and renovation plan, and operation optimization of specific energy substitution utilization, and lacks the strategy research of long-term layout of energy substitution utilization in large area. This paper puts forward a technical potential prediction method of coal to electricity based on the thermal equivalent method, which is based on the characteristics of regional coal consumption, and combined with the trend of adaptability and economy of energy substitution utilization. Also, the paper calculates the comprehensive benefit of coal to electricity according to the varieties of energy consumption and pollutant emission level of unit energy consumption in China’s future. The research result shows that the development technical potential of coal to electricity in China is huge, about 1.8 trillion kWh, including distributed electric heating, heat pump and electric heating boiler, mainly located in North China, East China, and Northeast China. The implementation of coal to electricity has remarkable comprehensive benefits in energy conservation and emission reduction, and improvement of energy consumption safety level. Case study shows the rationality of the proposed method.

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. Copyright © 2015. Published by Elsevier B.V.

Environmental and physical controls on northern terrestrial methane emissions across permafrost zones

USGS Publications Warehouse

Olefeldt, David; Turetsky, Merritt R.; Crill, Patrick M.; McGuire, A. David

2013-01-01

Methane (CH4) emissions from the northern high-latitude region represent potentially significant biogeochemical feedbacks to the climate system. We compiled a database of growing-season CH4 emissions from terrestrial ecosystems located across permafrost zones, including 303 sites described in 65 studies. Data on environmental and physical variables, including permafrost conditions, were used to assess controls on CH4 emissions. Water table position, soil temperature, and vegetation composition strongly influenced emissions and had interacting effects. Sites with a dense sedge cover had higher emissions than other sites at comparable water table positions, and this was an effect that was more pronounced at low soil temperatures. Sensitivity analysis suggested that CH4 emissions from ecosystems where the water table on average is at or above the soil surface (wet tundra, fen underlain by permafrost, and littoral ecosystems) are more sensitive to variability in soil temperature than drier ecosystems (palsa dry tundra, bog, and fen), whereas the latter ecosystems conversely are relatively more sensitive to changes of the water table position. Sites with near-surface permafrost had lower CH4 fluxes than sites without permafrost at comparable water table positions, a difference that was explained by lower soil temperatures. Neither the active layer depth nor the organic soil layer depth was related to CH4 emissions. Permafrost thaw in lowland regions is often associated with increased soil moisture, higher soil temperatures, and increased sedge cover. In our database, lowland thermokarst sites generally had higher emissions than adjacent sites with intact permafrost, but emissions from thermokarst sites were not statistically higher than emissions from permafrost-free sites with comparable environmental conditions. Overall, these results suggest that future changes to terrestrial high-latitude CH4 emissions will be more proximately related to changes in moisture, soil temperature, and vegetation composition than to increased availability of organic matter following permafrost thaw.

Project Final Report: Linking Plant Stress, Biogenic SOA, and CCN Production - A New Feedback in the Climate System?

DOE Office of Scientific and Technical Information (OSTI.GOV)

VanReken, Timothy; Balasingam, Muhunthan

2017-05-01

This project worked toward understanding the role of variable biogenic emissions in the formation of secondary organic aerosol (SOA), and in turn the potential for this aerosol to affect cloud droplet formation. It was premised on the idea that a changing climate could impose biogenic and abiogenic stresses on plants that would affect the emissions of volatile organic compounds (VOCs). The transformation of these VOCs to SOA and cloud condensation nuclei (CCN) implied the possibility of a feedback mechanism within the biosphere/atmosphere/climate system. The project’s activities centered on laboratory experiments to study the effects of stresses on plants and plant-derivedmore » material under controlled conditions, observing both the VOC emissions and the aerosol that formed from the oxidation of those VOCs. The results highlighted the potentially important contributions of stress and decomposition mechanisms to biogenic SOA formation. Related field measurements elucidated the conditions when these factors could be important in the ambient environment. The project also revealed repeated the complexity of the stress/VOC emission relationship, and the difficulty in expressing these relationships in a comprehensive manner.« less

Fate and potential environmental effects of methylenediphenyl diisocyanate and toluene diisocyanate released into the atmosphere.

PubMed

Tury, Bernard; Pemberton, Denis; Bailey, Robert E

2003-01-01

Information from a variety of sources has been collected and summarized to facilitate an overview of the atmospheric fate and potential environmental effects of emissions of methylenediphenyl diisocyanate (MDI) or toluene diisocyanate (TDI) to the atmosphere. Atmospheric emissions of both MDI and TDI are low, both in terms of concentration and mass, because of their low volatility and the need for careful control over all aspects of their lifecycle from manufacture through disposal. Typical emission losses for TDI are 25 g/t of TDI used in slabstock foam production. MDI emission losses are lower, often less than 1 g/t of MDI used. Dispersion modeling predicts that concentrations at the fenceline or beyond are very low for typical releases. Laboratory studies show that TDI (and by analogy MDI) does not react with water in the gas phase at a significant rate. The primary degradation reaction of these aromatic diisocyanates in the atmosphere is expected to be oxidation by OH radicals with an estimated half-life of one day. Laboratory studies also show that this reaction is not expected to result in increased ground-level ozone accumulation.

Characterization of the emissions impacts of hybrid excavators with a portable emissions measurement system (PEMS)-based methodology.

PubMed

Cao, Tanfeng; Russell, Robert L; Durbin, Thomas D; Cocker, David R; Burnette, Andrew; Calavita, Joseph; Maldonado, Hector; Johnson, Kent C

2018-04-13

Hybrid engine technology is a potentially important strategy for reduction of tailpipe greenhouse gas (GHG) emissions and other pollutants that is now being implemented for off-road construction equipment. The goal of this study was to evaluate the emissions and fuel consumption impacts of electric-hybrid excavators using a Portable Emissions Measurement System (PEMS)-based methodology. In this study, three hybrid and four conventional excavators were studied for both real world activity patterns and tailpipe emissions. Activity data was obtained using engine control module (ECM) and global positioning system (GPS) logged data, coupled with interviews, historical records, and video. This activity data was used to develop a test cycle with seven modes representing different types of excavator work. Emissions data were collected over this test cycle using a PEMS. The results indicated the HB215 hybrid excavator provided a significant reduction in tailpipe carbon dioxide (CO 2 ) emissions (from -13 to -26%), but increased diesel particulate matter (PM) (+26 to +27%) when compared to a similar model conventional excavator over the same duty cycle. Copyright © 2018 Elsevier B.V. All rights reserved.

40 CFR 63.652 - Emissions averaging provisions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... emissions average. This must include any Group 1 emission points to which the reference control technology... controls for a Group 1 emission point, the pollution prevention measure alone does not have to reduce... in control after November 15, 1990; (2) Group 1 emission points that are controlled by a reference...

40 CFR 63.652 - Emissions averaging provisions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... emissions average. This must include any Group 1 emission points to which the reference control technology... controls for a Group 1 emission point, the pollution prevention measure alone does not have to reduce... in control after November 15, 1990; (2) Group 1 emission points that are controlled by a reference...

Control of GHG emission at the microbial community level.

PubMed

Insam, H; Wett, B

2008-01-01

All organic material eventually is decomposed by microorganisms, and considerable amounts of C and N end up as gaseous metabolites. The emissions of greenhouse relevant gases like carbon dioxide, methane and nitrous oxides largely depend on physico-chemical conditions like substrate quality or the redox potential of the habitat. Manipulating these conditions has a great potential for reducing greenhouse gas emissions. Such options are known from farm and waste management, as well as from wastewater treatment. In this paper examples are given how greenhouse gas production might be reduced by regulating microbial processes. Biogas production from manure, organic wastes, and landfills are given as examples how methanisation may be used to save fossil fuel. Methane oxidation, on the other hand, might alleviate the problem of methane already produced, or the conversion of aerobic wastewater treatment to anaerobic nitrogen elimination through the anaerobic ammonium oxidation process might reduce N2O release to the atmosphere. Changing the diet of ruminants, altering soil water potentials or a change of waste collection systems are other measures that affect microbial activities and that might contribute to a reduction of carbon dioxide equivalents being emitted to the atmosphere.

Potential gases emissions from the combustion of municipal solid waste by bio-drying.

PubMed

Zhang, Dong-Qing; He, Pin-Jing; Shao, Li-Ming

2009-09-15

One aerobic and two combined hydrolytic-aerobic processes were set up to investigate the influence of bio-drying on the potential emissions of combustion gases and the quantitative relationships of potential emissions with organics degradation. Results showed that the bio-drying would result in the increase of the HCl and SO(2) emissions and potential for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) formation, but the decrease of NO(x) emissions in the combustion. The potential emissions of combustion gases were correlated with organics degradation (correlation coefficient, r=0.67 for HCl, r=0.96 for SO(2), r=0.91 for PCDD/Fs and r=-0.60 for NO(x)). Interestingly, the total emissions of combustion gases based on input waste could be minimized by bio-drying. The bio-drying caused a reduction of NO(x) emissions but a negligible variation of total emissions of HCl and SO(2) as well as the potential for total PCDD/Fs formation. Moreover, the bio-drying could significantly improve the ratio of gas emissions to low heating values. The mixed waste after bio-drying was more favorable for combustion and the combined process with insufficient aeration during the hydrolytic stage was proposed for the bio-drying operation.

Tunable and high-purity room temperature single-photon emission from atomic defects in hexagonal boron nitride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grosso, Gabriele; Moon, Hyowon; Lienhard, Benjamin

Two-dimensional van der Waals materials have emerged as promising platforms for solid-state quantum information processing devices with unusual potential for heterogeneous assembly. Recently, bright and photostable single photon emitters were reported from atomic defects in layered hexagonal boron nitride (hBN), but controlling inhomogeneous spectral distribution and reducing multi-photon emission presented open challenges. Here, we demonstrate that strain control allows spectral tunability of hBN single photon emitters over 6 meV, and material processing sharply improves the single photon purity. We observe high single photon count rates exceeding 7 × 10 6 counts per second at saturation, after correcting for uncorrelated photonmore » background. Furthermore, these emitters are stable to material transfer to other substrates. High-purity and photostable single photon emission at room temperature, together with spectral tunability and transferability, opens the door to scalable integration of high-quality quantum emitters in photonic quantum technologies.« less

Tunable and high-purity room temperature single-photon emission from atomic defects in hexagonal boron nitride

DOE PAGES

Grosso, Gabriele; Moon, Hyowon; Lienhard, Benjamin; ...

2017-09-26

Two-dimensional van der Waals materials have emerged as promising platforms for solid-state quantum information processing devices with unusual potential for heterogeneous assembly. Recently, bright and photostable single photon emitters were reported from atomic defects in layered hexagonal boron nitride (hBN), but controlling inhomogeneous spectral distribution and reducing multi-photon emission presented open challenges. Here, we demonstrate that strain control allows spectral tunability of hBN single photon emitters over 6 meV, and material processing sharply improves the single photon purity. We observe high single photon count rates exceeding 7 × 10 6 counts per second at saturation, after correcting for uncorrelated photonmore » background. Furthermore, these emitters are stable to material transfer to other substrates. High-purity and photostable single photon emission at room temperature, together with spectral tunability and transferability, opens the door to scalable integration of high-quality quantum emitters in photonic quantum technologies.« less

Calibration and validation of an activated sludge model for greenhouse gases no. 1 (ASMG1): prediction of temperature-dependent N₂O emission dynamics.

PubMed

Guo, Lisha; Vanrolleghem, Peter A

2014-02-01

An activated sludge model for greenhouse gases no. 1 was calibrated with data from a wastewater treatment plant (WWTP) without control systems and validated with data from three similar plants equipped with control systems. Special about the calibration/validation approach adopted in this paper is that the data are obtained from simulations with a mathematical model that is widely accepted to describe effluent quality and operating costs of actual WWTPs, the Benchmark Simulation Model No. 2 (BSM2). The calibration also aimed at fitting the model to typical observed nitrous oxide (N₂O) emission data, i.e., a yearly average of 0.5% of the influent total nitrogen load emitted as N₂O-N. Model validation was performed by challenging the model in configurations with different control strategies. The kinetic term describing the dissolved oxygen effect on the denitrification by ammonia-oxidizing bacteria (AOB) was modified into a Haldane term. Both original and Haldane-modified models passed calibration and validation. Even though their yearly averaged values were similar, the two models presented different dynamic N₂O emissions under cold temperature conditions and control. Therefore, data collected in such situations can potentially permit model discrimination. Observed seasonal trends in N₂O emissions are simulated well with both original and Haldane-modified models. A mechanistic explanation based on the temperature-dependent interaction between heterotrophic and autotrophic N₂O pathways was provided. Finally, while adding the AOB denitrification pathway to a model with only heterotrophic N₂O production showed little impact on effluent quality and operating cost criteria, it clearly affected N2O emission productions.

Impact of longevity on greenhouse gas emissions and profitability of individual dairy cows analysed with different system boundaries.

PubMed

Grandl, F; Furger, M; Kreuzer, M; Zehetmeier, M

2018-05-29

Dairy production systems are often criticized as being major emitters of greenhouse gases (GHG). In this context, the extension of the length of the productive life of dairy cows is gaining interest as a potential GHG mitigation option. In the present study, we investigated cow and system GHG emission intensity and profitability based on data from 30 dairy cows of different productive lifetime fed either no or limited amounts of concentrate. Detailed information concerning productivity, feeding and individual enteric methane emissions of the individuals was available from a controlled experiment and herd book databases. A simplified GHG balance was calculated for each animal based on the milk produced at the time of the experiment and for their entire lifetime milk production. For the lifetime production, we also included the emissions arising from potential beef produced by fattening the offspring of the dairy cows. This accounted for the effect that changes in the length of productive life will affect the replacement rate and thus the number of calves that can be used for beef production. Profitability was assessed by calculating revenues and full economic costs for the cows in the data set. Both emission intensity and profitability were most favourable in cows with long productive life, whereas cows that had not finished their first lactation performed particularly unfavourably with regard to their emissions per unit of product and rearing costs were mostly not repaid. Including the potential beef production, GHG emissions in relation to total production of animal protein also decreased with age, but the overall variability was greater, as the individual cow history (lifetime milk yield, twin births, stillbirths, etc.) added further sources of variation. The present results show that increasing the length of productive life of dairy cows is a viable way to reduce the climate impact and to improve profitability of dairy production.

Regional-scale carbon and greenhouse gas dynamics of organic matter amendments on grassland soils

NASA Astrophysics Data System (ADS)

Mayer, A.; Silver, W. L.

2017-12-01

While progress is being made toward emissions reductions, achieving the international warming target of no more than 2 °C by 2100 will require active removal of carbon dioxide from the atmosphere. This research explores the potential for grassland ecosystems to sequester soil carbon (C) and mitigate climate change over time. We parameterized a site-level biogeochemical model (DayCent) to predict the effect of compost applications on grassland net primary productivity, greenhouse gas emissions, and soil C storage and loss. We compare the results of the DayCent model from seven grassland regions across a broad climate gradient in CA. We also modeled the impact of climate change under a high emissions scenario (RCP 8.5) and reduced emissions scenario (RCP 4.5). Model results show that a single application of compost leads to a large net increase in soil C over several decades across all sites. Maximum soil C sequestration relative to control simulations occurred approximately 15 years after a ¼ inch compost was applied to the land, resulting in a maximum net C drawdown of approximately 6.6 Mg C/ha (Mendocino) by 2030 and a continued climate benefit from enhanced C storage through the end of the century. Compost application resulted in enhanced soil C in both climate scenarios, but the reduced emissions climate scenario resulted in greater net C storage than the high emissions scenario by 2100. This points to a virtuous cycle of simultaneous emissions reductions leading to enhanced climate change mitigation potential from land management strategies.

77 FR 34066 - Notice of Lodging of Consent Decree Under the Clean Air Act

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-08

... Organic Chemical Manufacturing Industry and Organic Hazardous Air Pollutants for Equipment Leaks). The... Defendants to implement an Enhanced Leak Detection and Repair Program to mitigate any potential excess emissions resulting from past CAA violations; implement controls on an API oil/water separator as additional...

Assessment of potential concerns associated with the use of cement kiln baghouse dust in FDOT concrete mixes.

DOT National Transportation Integrated Search

2013-08-01

As a means of controlling mercury (Hg) stack emissions at cement kiln operations, some facilities have proposed or have instituted a practice known as dust shuttling, where baghouse filter dust (BFD) is routed to be blended with the final cement prod...

Grassland Smoke Emission Measurement Supporting Multi-Modeling Framework Simulation of Rangeland Burning Practices for the Kansas Flint Hills Fire Experiment

EPA Science Inventory

Historically, frequent wildfires were essential for the maintenance of native prairie fire adapted ecosystems. Today prescribed fires are used to control invasive woody species and potentially improve forage production in these same prairie ecosystems for the beef-cattle industry...

High-Voltage MOSFET Switching Circuit

NASA Technical Reports Server (NTRS)

Jensen, Kenneth A.

1995-01-01

Circuit reliably switches power at supply potential of minus 1,500 V, with controlled frequency and duty cycle. Used in argon-plasma ion-bombardment equipment for texturing copper electrodes, as described in "Texturing Copper To Reduce Secondary Emission of Electrons" (LEW-15898), also adapted to use in powering gaseous flash lamps and stroboscopes.

40 CFR 63.9375 - What definitions apply to this subpart?

Code of Federal Regulations, 2012 CFR

2012-07-01

... malfunction, regardless or whether or not such failure is permitted by this subpart. Engine means any internal.... Malfunction means any sudden, infrequent, and not reasonably preventable failure of air pollution control... potential to cause, the emission limitations in an applicable standard to be exceeded. Failures that are...

40 CFR 63.9375 - What definitions apply to this subpart?

Code of Federal Regulations, 2014 CFR

2014-07-01

... malfunction, regardless or whether or not such failure is permitted by this subpart. Engine means any internal.... Malfunction means any sudden, infrequent, and not reasonably preventable failure of air pollution control... potential to cause, the emission limitations in an applicable standard to be exceeded. Failures that are...

40 CFR 63.9375 - What definitions apply to this subpart?

Code of Federal Regulations, 2013 CFR

2013-07-01

... malfunction, regardless or whether or not such failure is permitted by this subpart. Engine means any internal.... Malfunction means any sudden, infrequent, and not reasonably preventable failure of air pollution control... potential to cause, the emission limitations in an applicable standard to be exceeded. Failures that are...

40 CFR 63.9375 - What definitions apply to this subpart?

Code of Federal Regulations, 2011 CFR

2011-07-01

... malfunction, regardless or whether or not such failure is permitted by this subpart. Engine means any internal.... Malfunction means any sudden, infrequent, and not reasonably preventable failure of air pollution control... potential to cause, the emission limitations in an applicable standard to be exceeded. Failures that are...

Volatile organic compounds (VOCs) source profiles of on-road vehicle emissions in China.

PubMed

Hong-Li, Wang; Sheng-Ao, Jing; Sheng-Rong, Lou; Qing-Yao, Hu; Li, Li; Shi-Kang, Tao; Cheng, Huang; Li-Ping, Qiao; Chang-Hong, Chen

2017-12-31

Volatile Organic Compounds (VOCs) source profiles of on-road vehicles were widely studied as their critical roles in VOCs source apportionment and abatement measures in megacities. Studies of VOCs source profiles from on-road motor vehicles from 2001 to 2016 were summarized in this study, with a focus on the comparisons among different studies and the potential impact of different factors. Generally, non-methane hydrocarbons dominated the source profile of on-road vehicle emissions. Carbonyls, potential important components of vehicle emission, were seldom considered in VOCs emissions of vehicles in the past and should be paid more attention to in further study. VOCs source profiles showed some variations among different studies, and 6 factors were extracted and studied due to their impact to VOCs source profile of on-road vehicles. Vehicle types, being dependent on engine types, and fuel types were two dominant factors impacting VOCs sources profiles of vehicles. In comparison, impacts of ignitions, driving conditions and accumulated mileage were mainly due to their influence on the combustion efficiency. An opening and interactive database of VOCs from vehicle emissions was critically essential in future, and mechanisms of sharing and inputting relative research results should be formed to encourage researchers join the database establishment. Correspondingly, detailed quality assurance and quality control procedures were also very important, which included the information of test vehicles and test methods as detailed as possible. Based on the community above, a better uncertainty analysis could be carried out for the VOCs emissions profiles, which was critically important to understand the VOCs emission characteristics of the vehicle emissions. Copyright © 2017 Elsevier B.V. All rights reserved.

The global economic long-term potential of modern biomass in a climate-constrained world

NASA Astrophysics Data System (ADS)

Klein, David; Humpenöder, Florian; Bauer, Nico; Dietrich, Jan Philipp; Popp, Alexander; Bodirsky, Benjamin Leon; Bonsch, Markus; Lotze-Campen, Hermann

2014-07-01

Low-stabilization scenarios consistent with the 2 °C target project large-scale deployment of purpose-grown lignocellulosic biomass. In case a GHG price regime integrates emissions from energy conversion and from land-use/land-use change, the strong demand for bioenergy and the pricing of terrestrial emissions are likely to coincide. We explore the global potential of purpose-grown lignocellulosic biomass and ask the question how the supply prices of biomass depend on prices for greenhouse gas (GHG) emissions from the land-use sector. Using the spatially explicit global land-use optimization model MAgPIE, we construct bioenergy supply curves for ten world regions and a global aggregate in two scenarios, with and without a GHG tax. We find that the implementation of GHG taxes is crucial for the slope of the supply function and the GHG emissions from the land-use sector. Global supply prices start at 5 GJ-1 and increase almost linearly, doubling at 150 EJ (in 2055 and 2095). The GHG tax increases bioenergy prices by 5 GJ-1 in 2055 and by 10 GJ-1 in 2095, since it effectively stops deforestation and thus excludes large amounts of high-productivity land. Prices additionally increase due to costs for N2O emissions from fertilizer use. The GHG tax decreases global land-use change emissions by one-third. However, the carbon emissions due to bioenergy production increase by more than 50% from conversion of land that is not under emission control. Average yields required to produce 240 EJ in 2095 are roughly 600 GJ ha-1 yr-1 with and without tax.

Effect of Soil Nutrient on Production and Diversity of Volatile Terpenoids from Plants

PubMed Central

Ormeño, E; Fernandez, C

2012-01-01

Terpenoid production (emission and storage) within foliage plays direct and indirect defensive and protective functions for the plant, mediates complex trophic relationships and controls the oxidation capacity of the atmosphere. Both biotic and abiotic conditions alter terpenoid production, with herbivory, light and temperature effects being reasonably well understood. In this manuscript, the state of the science about nutrient effect on terpenoid production is reviewed. The focus is on isoprene emissions and mono- and sesquiterpenoid emissions and concentrations according to fertilizing treatments and their potential interaction with other environmental factors. Ecological, physiological, biochemical and biophysical hypothesis formulated over research investigations are exposed and several points are highlighted as future research perspectives which could help to elucidate the apparent contrasting results. PMID:23097639

Natural gas anodes for aluminium electrolysis in molten fluorides.

PubMed

Haarberg, Geir Martin; Khalaghi, Babak; Mokkelbost, Tommy

2016-08-15

Industrial primary production of aluminium has been developed and improved over more than 100 years. The molten salt electrolysis process is still suffering from low energy efficiency and considerable emissions of greenhouse gases (CO2 and PFC). A new concept has been suggested where methane is supplied through the anode so that the CO2 emissions may be reduced significantly, the PFC emissions may be eliminated and the energy consumption may decrease significantly. Porous carbon anodes made from different graphite grades were studied in controlled laboratory experiments. The anode potential, the anode carbon consumption and the level of HF gas above the electrolyte were measured during electrolysis. In some cases it was found that the methane oxidation was effectively participating in the anode process.

High efficiency and stable white OLED using a single emitter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Jian

2016-01-18

The ultimate objective of this project was to demonstrate an efficient and stable white OLED using a single emitter on a planar glass substrate. The focus of the project is on the development of efficient and stable square planar phosphorescent emitters and evaluation of such class of materials in the device settings. Key challenges included improving the emission efficiency of molecular dopants and excimers, controlling emission color of emitters and their excimers, and improving optical and electrical stability of emissive dopants. At the end of this research program, the PI has made enough progress to demonstrate the potential of excimer-basedmore » white OLED as a cost-effective solution for WOLED panel in the solid state lighting applications.« less

Constructing a sustainable power sector in China: current and future emissions of coal-fired power plants from 2010 to 2030

NASA Astrophysics Data System (ADS)

Tong, D.; Zhang, Q.

2017-12-01

As the largest energy infrastructure in China, power sector consumed more coal than any other sector and threatened air quality and greenhouse gas (GHG) abatement target. In this work, we assessed the evolution of coal-fired power plants in China during 2010-2030 and the evolution of associated emissions for the same period by using a unit-based emission projection model which integrated the historical power plants information, turnover of the future power plant fleet, and the evolution of end-of-pipe control technologies. We found that, driven by the stringent environmental legislation, SO2, NOx, and PM2.5 emissions from China's coal-fired power plants decreased by 49%, 45%, and 24% respectively during 2010-2015, comparing to 14% increase of coal consumption and 15% increase in CO2 emissions. We estimated that under current national energy development planning, coal consumption and CO2 emissions from coal-fired power plants will continue to increase until 2030, in which against the China's Intended Nationally Determined Contributions (INDCs) targets. Early retirement of old and low-efficient power plants will cumulatively reduce 2.2 Pg CO2 emissions from the baseline scenario during 2016-2030, but still could not curb CO2 emissions from the peak before 2030. Owing to the implementation of "near zero" emission control policy, we projected that emissions of air pollutants will significantly decrease during the same period under all scenarios, indicating the decoupling trends of air pollutants and CO2 emissions. Although with limited direct emission reduction benefits, increasing operating hours of power plants could avoid 236 GW of new power plants construction, which could indirectly reduce emissions embodied in the construction activity. Our results identified a more sustainable pathway for China's coal-fired power plants, which could reduce air pollutant emissions, improve the energy efficiency, and slow down the construction of new units. However, continuous construction of new coal-fired power plants driven by increased electricity demand would pose a potential threat to climate change mitigation and China's peak carbon pledge, and more aggressive CO2 emission reduction policy should be implemented in the future.

Optical redox ratio using endogenous fluorescence to assess the metabolic changes associated with treatment response of bioconjugated gold nanoparticles in streptozotocin-induced diabetic rats

NASA Astrophysics Data System (ADS)

Adavallan, K.; Gurushankar, K.; Nazeer, Shaiju S.; Gohulkumar, M.; Jayasree, Ramapurath S.; Krishnakumar, N.

2017-06-01

Fluorescence spectroscopic techniques have the potential to assess the metabolic changes during disease development and evaluation of treatment response in a non-invasive and label-free manner. The present study aims to evaluate the effect of mulberry-mediated gold nanoparticles (MAuNPs) in comparison with mulberry leaf extract alone (MLE) for monitoring endogenous fluorophores and to quantify the metabolic changes associated with mitochondrial redox states during streptozotocin-induced diabetic liver tissues using fluorescence spectroscopy. Two mitochondrial metabolic coenzymes, reduced nicotinamide dinucleotide (NADH) and oxidized flavin adenine dinucleotide (FAD) are autofluorescent and are important optical biomarkers to estimate the redox state of a cell. Significant differences in the autofluorescence spectral signatures between the control and the experimental diabetic animals have been noticed under the excitation wavelength at 320 nm with emission ranging from 350-550 nm. A direct correlation between the progression of diabetes and the levels of collagen and optical redox ratio was observed. The results revealed that a significant increase in the emission of collagen in diabetic liver tissues as compared with the control liver tissues. Moreover, there was a significant decrease in the optical redox ratio (FAD/(FAD  +  NADH)) observed in diabetic control liver tissues, which indicates an increased oxidative stress compared to the liver tissues of control rats. Further, the extent of increased oxidative stress was confirmed by the reduced levels of reduced glutathione (GSH) in diabetic liver tissues. On a comparative basis, treatment with MAuNPs was found to be more effective than MLE for reducing the progression of diabetes and improving the optical redox ratio to a near normal range in streptozotocin-induced diabetic liver tissues. Furthermore, principal component analysis followed by linear discriminant analysis (PC-LDA) has been used to classify the autofluorescence emission spectra from the control and the experimental group of diabetic rats. The results of this study raise the important possibility that fluorescence spectroscopy in conjunction with multivariate statistical analysis has tremendous potential for monitoring or potentially predicting responses to therapy.

Satellite Spacecraft Charging Control Materials.

DTIC Science & Technology

1980-04-01

Surface potential in terms of beam energy 923.4.4 Typical current recordings 92 3 - 5 Analysis III 3.5.1 Background ill 3.5.2 Silica fabric behaviour 114...3521 surface potentials, leakage and secondary electron emission currents 114 3521-1 variation with time 114I 3521-2 variation with the beam energy ...Irradiations 51 Figure 15 Silica Fabric - FEP - Aluminum Foil Composite 56 Figure 16 Electron Energy Spectrum After Scattering through and Aluminum Foil

Gallium Nitride Nanowires and Heterostructures: Toward Color-Tunable and White-Light Sources.

PubMed

Kuykendall, Tevye R; Schwartzberg, Adam M; Aloni, Shaul

2015-10-14

Gallium-nitride-based light-emitting diodes have enabled the commercialization of efficient solid-state lighting devices. Nonplanar nanomaterial architectures, such as nanowires and nanowire-based heterostructures, have the potential to significantly improve the performance of light-emitting devices through defect reduction, strain relaxation, and increased junction area. In addition, relaxation of internal strain caused by indium incorporation will facilitate pushing the emission wavelength into the red. This could eliminate inefficient phosphor conversion and enable color-tunable emission or white-light emission by combining blue, green, and red sources. Utilizing the waveguiding modes of the individual nanowires will further enhance light emission, and the properties of photonic structures formed by nanowire arrays can be implemented to improve light extraction. Recent advances in synthetic methods leading to better control over GaN and InGaN nanowire synthesis are described along with new concept devices leading to efficient white-light emission. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Clean Air Act: A time to assess impacts and management options

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldberg, T.; Repa, E.

The Clean Air Act Amendments of 1990 significantly altered the complexion of air emission regulation and for the first time established requirements for comprehensive emission control strategies. None of the provisions of this act will have as great an impact on the waste management industry as will the General Operating Permit Provisions of Title V. Title V establishes a program for issuing operating permits to all major sources (and certain other sources) of air pollutants in the U.S. These permits will collect in one place all applicable requirements, limitations, and conditions governing regulated air emissions. While past air regulations governedmore » specific air emissions sources, as of November 1993 the law requires states and localities to regulate emissions from all major stationary sources that directly emit, or have the potential to emit, 100 tons or more of any pollutant, 10 tons or more of a single hazardous air pollutant, or 25 tons or more of two or more hazardous air pollutants.« less

Terahertz Focusing and Polarization Control in Large-Area Bias-Free Semiconductor Emitters

NASA Astrophysics Data System (ADS)

Carthy, Joanna L.; Gow, Paul C.; Berry, Sam A.; Mills, Ben; Apostolopoulos, Vasilis

2018-03-01

We show that, when large-area multiplex terahertz semiconductor emitters, that work on diffusion currents and Schottky potentials, are illuminated by ultrashort optical pulses they can radiate a directional electromagnetic terahertz pulse which is controlled by the angular spectrum of the incident optical beam. Using the lens that focuses the incident near-infrared pulse, we have demonstrated THz emission focusing in free space, at the same point where the optical radiation would focus. We investigated the beam waist and Gouy phase shift of the THz emission as a function of frequency. We also show that the polarization profile of the emitted THz can be tailored by the metallic patterning on the semiconductor, demonstrating radial polarization when a circular emitter design is used. Our techniques can be used for fast THz beam steering and mode control for efficiently coupling to waveguides without the need for THz lenses or parabolic mirrors.

Kudzu (Pueraria montana) invasion doubles emissions of nitric oxide and increases ozone pollution.

PubMed

Hickman, Jonathan E; Wu, Shiliang; Mickley, Loretta J; Lerdau, Manuel T

2010-06-01

The nitrogen-fixing legume kudzu (Pueraria montana) is a widespread invasive plant in the southeastern United States with physiological traits that may lead to important impacts on ecosystems and the atmosphere. Its spread has the potential to raise ozone levels in the region by increasing nitric oxide (NO) emissions from soils as a consequence of increasing nitrogen (N) inputs and cycling in soils. We studied the effects of kudzu invasions on soils and trace N gas emissions at three sites in Madison County, Georgia in 2007 and used the results to model the effects of kudzu invasion on regional air quality. We found that rates of net N mineralization increased by up to 1,000%, and net nitrification increased by up to 500% in invaded soils in Georgia. Nitric oxide emissions from invaded soils were more than 100% higher (2.81 vs. 1.24 ng NO-N cm(-2) h(-1)). We used the GEOS-Chem chemical transport model to evaluate the potential impact of kudzu invasion on regional atmospheric chemistry and air quality. In an extreme scenario, extensive kudzu invasion leads directly to an increase in the number of high ozone events (above 70 ppb) of up to 7 days each summer in some areas, up from 10 to 20 days in a control scenario with no kudzu invasion. These results establish a quantitative link between a biological invasion and ozone formation and suggest that in this extreme scenario, kudzu invasion can overcome some of the air quality benefits of legislative control.

The role of ecophysiology in determining monoterpene concentrations and emissions from pinyon pine under drought conditions

NASA Astrophysics Data System (ADS)

Trowbridge, A. M.; Adams, H. D.; Breshears, D. D.; Stoy, P.; Monson, R. K.

2012-12-01

While much research has focused on the primary metabolic mechanisms underlying pinyon pine's sensitivity to severe and abrupt drought conditions, there remains a gap in our knowledge concerning how the resulting shift in carbon allocation toward plant secondary compounds, particularly monoterpenes, affects both atmospheric process and ecological species interactions. Because of the large global emission rate of monoterpenes and their effect on atmospheric chemistry, identifying the primary controls over and sensitivities to environmental change is critical for global emission models. Furthermore, monoterpenes are also known to impact insect behavior and act as defense compounds against herbivores, contributing to fluctuations in the population densities of herbivores either directly through toxicity, or indirectly by influencing an insect's susceptibility to parasitism. While pinyon mortality events are thought to be exacerbated by their susceptibility to herbivores resulting from weakened secondary chemical defenses, the impact of current and predicted drought on the chemical defense status of pinyons and the potential consequences for atmospheric composition and ecological interactions remains unknown. We performed a manipulative field study to untangle the effects of drought on plant carbon assimilation, growth, and defense throughout the year. Transplanting pinyons from their natural habitat into a desert environment, we were able to increase mean annual temperature by ~4 degrees C. Throughout the growing season, we measured pinyon physiology and monoterpene composition and emissions under different water (well-watered, ambient, or drought-stresed) and temperature (natural pinyon habitat or desert transplants) regimes. We hypothesized that increased drought would increase tissue concentrations in accordance with the carbon-nutrient balance hypothesis (CNBH). Furthermore, we predicted that higher temperatures and lower water availability together would influence monoterpene emission rates, but only through shifts in tissue concentrations. Our results showed that neither total needle monoterpene concentrations nor emission rates differed between sites, and furthermore, foliar concentrations were not a significant predictor of emissions. Rather, stomatal conductance was significantly and positively correlated with monoterpene emission rates below 1 μg C gDW-1 h-1, explaining 10% of the variation in the data when measured across the growing season, but only in the pinyon pine native habitat. However, we also observed periods of emission rates > 1 μg C gDW-1 h-1at both sites during the month of June, which were not controlled by stomatal conductance or tissue monoterpene concentration. Thus, there appear to be yet-to-be-identified phenological factors that exert control over these extremely high mid-season emission rates. Our results suggest that drought has no significant influence over tissue monoterpene concentrations in this system, which are likely under tight genetic control. However, drought and phenology may exert dominant controls over the emission of monoterpenes through influences on stomatal conductance and other plant processes. Our results demonstrate a greater role than previously recognized for ecophysiological processes in controlling monoterpene fluxes from semi-arid conifer species.

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

NASA Astrophysics Data System (ADS)

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

2017-04-01

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

Predicted impact of thermal power generation emission control measures in the Beijing-Tianjin-Hebei region on air pollution over Beijing, China.

PubMed

Wang, Liqiang; Li, Pengfei; Yu, Shaocai; Mehmood, Khalid; Li, Zhen; Chang, Shucheng; Liu, Weiping; Rosenfeld, Daniel; Flagan, Richard C; Seinfeld, John H

2018-01-17

Widespread economic growth in China has led to increasing episodes of severe air pollution, especially in major urban areas. Thermal power plants represent a particularly important class of emissions. Here we present an evaluation of the predicted effectiveness of a series of recently proposed thermal power plant emission controls in the Beijing-Tianjin-Hebei (BTH) region on air quality over Beijing using the Community Multiscale Air Quality(CMAQ) atmospheric chemical transport model to predict CO, SO 2 , NO 2 , PM 2.5 , and PM 10 levels. A baseline simulation of the hypothetical removal of all thermal power plants in the BTH region is predicted to lead to 38%, 23%, 23%, 24%, and 24% reductions in current annual mean levels of CO, SO 2 , NO 2 , PM 2.5 , and PM 10 in Beijing, respectively. Similar percentage reductions are predicted in the major cities in the BTH region. Simulations of the air quality impact of six proposed thermal power plant emission reduction strategies over the BTH region provide an estimate of the potential improvement in air quality in the Beijing metropolitan area, as a function of the time of year.

Simulating the Impact of Premixed Charge Compression Ignition on Light-Duty Diesel Fuel Economy and Emissions of Particulates and NOx

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Zhiming; Daw, C Stuart; Wagner, Robert M

2013-01-01

We utilize the Powertrain Systems Analysis Toolkit (PSAT) combined with transient engine and aftertreatment component models implemented in Matlab/Simulink to simulate the effect of premixed charge compression ignition (PCCI) on the fuel economy and emissions of light-duty diesel-powered conventional and hybrid electric vehicles (HEVs). Our simulated engine is capable of both conventional diesel combustion (CDC) and premixed charge compression ignition (PCCI) over real transient driving cycles. Our simulated aftertreatment train consists of a diesel oxidation catalyst (DOC), lean NOx trap (LNT), and catalyzed diesel particulate filter (DPF). The results demonstrate that, in the simulated conventional vehicle, PCCI can significantly reducemore » fuel consumption and emissions by reducing the need for LNT and DPF regeneration. However, the opportunity for PCCI operation in the simulated HEV is limited because the engine typically experiences higher loads and multiple stop-start transients that are outside the allowable PCCI operating range. Thus developing ways of extending the PCCI operating range combined with improved control strategies for engine and emissions control management will be especially important for realizing the potential benefits of PCCI in HEVs.« less

Influence of Light and Temperature on Monoterpene Emission Rates from Slash Pine

PubMed Central

Tingey, David T.; Manning, Marybeth; Grothaus, Louis C.; Burns, Walter F.

1980-01-01

There is a growing awareness of vegetation's role as a source of potentially reactive hydrocarbons that may serve as photochemical oxidant precursors. This study assessed the influence of light and temperature, independently, on monoterpene emissions from slash pine (Pinus elliottii Engelm.). Plants were preconditioned in a growth chamber, then transferred to an environmentally controlled gas exchange chamber. Samples of the chamber atmosphere were collected; the monoterpenes were concentrated cryogenically and measured by gas chromatography. Five monoterpenes (α-pinene, β-pinene, myrcene, limonene, and β-phellandrene) were present in the vapor phase surrounding the plants in sufficient quantity for reliable measurement. Light did not directly influence monoterpene emission rates since the emissions were similar in both the dark and at various light intensities. Monoterpene emission rates increased exponentially with temperature (i. e. emissions depend on temperature in a log-linear manner). The summed emissions of the five monoterpenes ranged from 3 to 21 micrograms C per gram dry weight per hour as temperature was increased from 20 to 46 C. Initially, emission rates from heat-stressed needles were similar to healthy needles, but rates decreased 11% per day. Daily carbon loss through monoterpene emissions accounted for approximately 0.4% of the carbon fixed during photosynthesis. PMID:16661285

Influence of light and temperature on monoterpene emission rates from slash pine.

PubMed

Tingey, D T; Manning, M; Grothaus, L C; Burns, W F

1980-05-01

There is a growing awareness of vegetation's role as a source of potentially reactive hydrocarbons that may serve as photochemical oxidant precursors. This study assessed the influence of light and temperature, independently, on monoterpene emissions from slash pine (Pinus elliottii Engelm.). Plants were preconditioned in a growth chamber, then transferred to an environmentally controlled gas exchange chamber. Samples of the chamber atmosphere were collected; the monoterpenes were concentrated cryogenically and measured by gas chromatography. Five monoterpenes (alpha-pinene, beta-pinene, myrcene, limonene, and beta-phellandrene) were present in the vapor phase surrounding the plants in sufficient quantity for reliable measurement. Light did not directly influence monoterpene emission rates since the emissions were similar in both the dark and at various light intensities. Monoterpene emission rates increased exponentially with temperature (i. e. emissions depend on temperature in a log-linear manner). The summed emissions of the five monoterpenes ranged from 3 to 21 micrograms C per gram dry weight per hour as temperature was increased from 20 to 46 C. Initially, emission rates from heat-stressed needles were similar to healthy needles, but rates decreased 11% per day. Daily carbon loss through monoterpene emissions accounted for approximately 0.4% of the carbon fixed during photosynthesis.

A Regionally-Specific Assessment of the Carbon Abatement Potential of Biochar

NASA Astrophysics Data System (ADS)

Birch, G.; Field, J.; Keske, C.; DeFoort, M.; Cotrufo, M.

2012-12-01

Biochar, the solid carbon-rich co-product of certain bioenergy conversion technologies, is receiving a great deal of attention as a strategy for sequestering carbon in soils and improving the performance of agricultural systems. Several studies have attempted to quantify the lifecycle carbon abatement potential of biochar systems, considering emissions associated with feedstock provisioning and processing, energy co-production, agronomic system impacts (yield increases and nitrous oxide emission suppression), and the recalcitrance of biochar in soil, as well as accounting for the carbon abatement value of using the char as a fuel that is foregone when it is used as a soil amendment instead. These assessments typically focus on biochar production in advanced, efficient slow pyrolysis systems, despite the fact that much biochar is currently produced through small-scale carbonization or gasification systems that lack energy recovery or even emission control capability. Here, a mechanistic biochar system assessment model is presented, capable of estimating system carbon abatement value and profitability for different feedstocks, conversion technologies and temperatures, and application into different agricultural soils. The variation of biochar recalcitrance in soil as a function of production temperature is considered, and agricultural impacts are assessed in the context of biochar's liming value, an effect that is straightforward to quantify and that has often been implicated in observed crop yield increases or nitrous oxide emission reductions. The analysis is rigorous in that tradeoffs between biochar production quantity and quality are endogenized, but conservative in that other potential agronomic benefits of biochar (e.g. improved soil water holding capacity) are not considered. This model is applied to a case study of bioenergy and biochar co-production in northern Colorado using beetle-killed pine wood and slash as a feedstock. Preliminary results suggest that a) high system carbon abatement potentials are possible in the case study scenario, but only in systems that control air pollutant emissions and recover energy; b) biochar has more value as a soil amendment than a fuel when produced at high temperatures and applied to soils of low pH and low buffering capacity; and c) the carbon abatement value of agronomic impacts in temperate systems is relatively minor compared to other parts of the lifecycle. Additional results will be presented for which an optimal system design is identified and the analysis scaled-up to reflect the total beetle-kill feedstock availability in the state of Colorado in order to estimate the total regional carbon-mitigation potential of the technology.

Cooking with Fire: The Mutagenicity- and PAH-Emission ...

EPA Pesticide Factsheets

Emissions from solid fuels used for cooking cause ~4 million premature deaths per year. Advanced solid-fuel cookstoves are a potential solution, but they should be assessed by appropriate performance indicators, including biological effects. We evaluated two categories of solid-fuel cookstoves for 8 pollutant- and 4 mutagenicity-emission factors, correlated the mutagenicity-emission factors, and compared them to those of other combustion emissions. We burned red oak in a 3-stone fire (TSF), a natural-draft stove (NDS), and a forced-draft stove (FDS); we combusted propane as a liquified petroleum gas control fuel. We determined emission factors based on useful energy (megajoules delivered, MJd) for carbon monoxide, nitrogen oxides (NOx), black carbon, methane, total hydrocarbons, 32 polycyclic aromatic hydrocarbons, PM2.5, levoglucosan (a wood-smoke marker), and mutagenicity in Salmonella. Other than NOx the emission factors per MJd correlated highly among each other (r2 ≥ 0.92); NOx correlated 0.58-0.76 with the other emission factors. Excluding NOx, the NDS and FDS reduced the emission factors on average 68 and 92%, respectively, relative to the TSF. Nonetheless, the mutagenicity-emission factor based on fuel energy used (MJthermal) for the most efficient stove (FDS) was intermediate to that of a large diesel bus engine and a small diesel generator. Both mutagenicity- and pollutant-emission factors may be informative for characterizing cookstove

Two-step fabrication of ZnO-PVP composites with tunable visible emissions

NASA Astrophysics Data System (ADS)

Agulto, Verdad C.; Empizo, Melvin John F.; Kawano, Keisuke; Minami, Yuki; Yamanoi, Kohei; Sarukura, Nobuhiko; Yago, Allan Christopher C.; Sarmago, Roland V.

2018-02-01

We report a two-step fabrication of zinc oxide-polyvinylpyrrolidone (ZnO-PVP) composites for potential phosphor-based applications. The composites are fabricated by initially preparing ZnO microrods using hydrothermal growth method and then dip-coating the microrods into aqueous PVP solutions with varying molar concentrations. The as-prepared ZnO microrods exhibit smooth surfaces and broad visible emissions, while the ZnO-PVP composites have pitted surfaces with shifted and reduced visible emissions. These changes in the structural and optical properties, which are found to depend on the PVP concentration, are attributed to the adsorption of PVP on the microrod surface. Although the surface morphology and visible emission are modified by PVP, the composites still maintain a hexagonal wurtzite crystal structure and near-band-edge ultraviolet (UV) emission similar with the as-prepared microrods. Our results therefore suggest that the ZnO-PVP composites can be used as phosphors that offer not only properties found in both ZnO and PVP but also tunable visible emissions which can be controlled during material fabrication.

Spin-controlled ultrafast vertical-cavity surface-emitting lasers

NASA Astrophysics Data System (ADS)

Höpfner, Henning; Lindemann, Markus; Gerhardt, Nils C.; Hofmann, Martin R.

2014-05-01

Spin-controlled semiconductor lasers are highly attractive spintronic devices providing characteristics superior to their conventional purely charge-based counterparts. In particular, spin-controlled vertical-cavity surface emitting lasers (spin-VCSELs) promise to offer lower thresholds, enhanced emission intensity, spin amplification, full polarization control, chirp control and ultrafast dynamics. Most important, the ability to control and modulate the polarization state of the laser emission with extraordinarily high frequencies is very attractive for many applications like broadband optical communication and ultrafast optical switches. We present a novel concept for ultrafast spin-VCSELs which has the potential to overcome the conventional speed limitation for directly modulated lasers by the relaxation oscillation frequency and to reach modulation frequencies significantly above 100 GHz. The concept is based on the coupled spin-photon dynamics in birefringent micro-cavity lasers. By injecting spin-polarized carriers in the VCSEL, oscillations of the coupled spin-photon system can by induced which lead to oscillations of the polarization state of the laser emission. These oscillations are decoupled from conventional relaxation oscillations of the carrier-photon system and can be much faster than these. Utilizing these polarization oscillations is thus a very promising approach to develop ultrafast spin-VCSELs for high speed optical data communication in the near future. Different aspects of the spin and polarization dynamics, its connection to birefringence and bistability in the cavity, controlled switching of the oscillations, and the limitations of this novel approach will be analysed theoretically and experimentally for spin-polarized VCSELs at room temperature.

Simulated Fuel Economy and Emissions Performance during City and Interstate Driving for a Heavy-Duty Hybrid Truck

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daw, C. Stuart; Gao, Zhiming; Smith, David E.

2013-04-08

We compare simulated fuel economy and emissions for both conventional and hybrid class 8 heavy-duty diesel trucks operating over multiple urban and highway driving cycles. Both light and heavy freight loads were considered, and all simulations included full aftertreatment for NOx and particulate emissions controls. The aftertreatment components included a diesel oxidation catalyst (DOC), urea-selective catalytic NOx reduction (SCR), and a catalyzed diesel particulate filter (DPF). Our simulated hybrid powertrain was configured with a pre-transmission parallel drive, with a single electric motor between the clutch and gearbox. A conventional HD truck with equivalent diesel engine and aftertreatment was also simulatedmore » for comparison. Our results indicate that hybridization can significantly increase HD fuel economy and improve emissions control in city driving. However, there is less potential hybridization benefit for HD highway driving. A major factor behind the reduced hybridization benefit for highway driving is that there are fewer opportunities to utilize regenerative breaking. Our aftertreatment simulations indicate that opportunities for passive DPF regeneration are much greater for both hybrid and conventional trucks during highway driving due to higher sustained exhaust temperatures. When passive DPF regeneration is extensively utilized, the fuel penalty for particulate control is virtually eliminated, except for the 0.4%-0.9% fuel penalty associated with the slightly higher exhaust backpressure.« less

Top-down control of methane emission and nitrogen cycling by waterfowl.

PubMed

Winton, R Scott; Richardson, Curtis J

2017-01-01

Aquatic herbivores impose top-down control on the structure of wetland ecosystems, but the biogeochemical consequences of herbivory on methane (CH 4 ) and nitrogen (N) are poorly known. To investigate the top-down effects of waterfowl on wetland biogeochemistry, we implemented exclosure experiments in a major waterfowl overwintering wetland in the southeastern United States over two growing seasons. We found that herbivory inhibited the oxidation of CH 4 , leading to a mean increase in emission by 230% over control plots, and prevented nitrification, as indicated by low nitrate availability and undetectable emissions of nitrous oxide. Herbivory reduced belowground biomass of macrophytes, retarding the subsequent spring emergence of aerenchymous stems, effectively starving wetland soils of oxygen necessary for CH 4 oxidation and nitrification. The recognition that important populations of aquatic herbivores may influence the capacity for wetlands to emit greenhouse gases and cycle N is particularly salient in the context of climate change and nutrient pollution mitigation goals. For example, our results suggest that (1) annual emissions of 23 Gg CH 4 /yr from ~57 000 ha of publicly owned waterfowl impoundments in the southeastern United States could be tripled by overgrazing and that (2) waterfowl impoundments may export as much N as agricultural fields. We discuss potential implications for habitat management in the context of historic wetland loss and waterfowl population recovery. © 2016 by the Ecological Society of America.

Mutagenicity and Pollutant Emission Factors of Solid-Fuel Cookstoves: Comparison with Other Combustion Sources

PubMed Central

Mutlu, Esra; Warren, Sarah H.; Ebersviller, Seth M.; Kooter, Ingeborg M.; Schmid, Judith E.; Dye, Janice A.; Linak, William P.; Gilmour, M. Ian; Jetter, James J.; Higuchi, Mark; DeMarini, David M.

2016-01-01

Background: Emissions from solid fuels used for cooking cause ~4 million premature deaths per year. Advanced solid-fuel cookstoves are a potential solution, but they should be assessed by appropriate performance indicators, including biological effects. Objective: We evaluated two categories of solid-fuel cookstoves for eight pollutant and four mutagenicity emission factors, correlated the mutagenicity emission factors, and compared them to those of other combustion emissions. Methods: We burned red oak in a 3-stone fire (TSF), a natural-draft stove (NDS), and a forced-draft stove (FDS), and we combusted propane as a liquified petroleum gas control fuel. We determined emission factors based on useful energy (megajoules delivered, MJd) for carbon monoxide, nitrogen oxides (NOx), black carbon, methane, total hydrocarbons, 32 polycyclic aromatic hydrocarbons, PM2.5, levoglucosan (a wood-smoke marker), and mutagenicity in Salmonella. Results: With the exception of NOx, the emission factors per MJd were highly correlated (r ≥ 0.97); the correlation for NOx with the other emission factors was 0.58–0.76. Excluding NOx, the NDS and FDS reduced the emission factors an average of 68 and 92%, respectively, relative to the TSF. Nevertheless, the mutagenicity emission factor based on fuel energy used (MJthermal) for the most efficient stove (FDS) was between those of a large diesel bus engine and a small diesel generator. Conclusions: Both mutagenicity and pollutant emission factors may be informative for characterizing cookstove performance. However, mutagenicity emission factors may be especially useful for characterizing potential health effects and should be evaluated in relation to health outcomes in future research. An FDS operated as intended by the manufacturer is safer than a TSF, but without adequate ventilation, it will still result in poor indoor air quality. Citation: Mutlu E, Warren SH, Ebersviller SM, Kooter IM, Schmid JE, Dye JA, Linak WP, Gilmour MI, Jetter JJ, Higuchi M, DeMarini DM. 2016. Mutagenicity and pollutant emission factors of solid-fuel cookstoves: comparison with other combustion sources. Environ Health Perspect 124:974–982; http://dx.doi.org/10.1289/ehp.1509852 PMID:26895221

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brosha, Eric L; Mukundan, Rangachary; Nelson, Mark A

The purpose of this research effort is to develop a low cost on-board Nitrogen Oxide (NO{sub x})/Ammonia (NH{sub 3}) sensor that can not only be used for emissions control but has the potential to improve efficiency through better monitoring of the combustion process and feedback control in both vehicle and stationary systems. Over the past decade, Los AJamos National Laboratory (LANL) has developed a unique class of electrochemical gas sensors for the detection of carbon monoxide, hydrocarbons, hydrogen and nitrogen oxides. These sensors are based on the mixed-potential phenomenon and are a modification of the existing automotive lambda (oxygen) sensormore » and have the potential to meet the stringent sensitivity, selectivity and stability requirements of an on-board emissions/engine control sensor system. The current state of the art LANL technology is based on the stabilization of the electrochemical interfaces and relies on an externally heated, hand-made, tape cast device. We are now poised to apply our patented sensing principles in a mass production sensor platform that is more suitable for real world engine-out testing such as on dynamometers for vehicle applications and for exhaust-out testing in heavy boilers/SCR systems in power plants. In this present work, our goal is to advance towards commercialization of this technology by packaging the unique LANL sensor design in a standard automotive sensor-type platform. This work is being performed with the help of a leading US technical ceramics firm, utilizing commercial manufacturing techniques. Initial tape cast platforms with screen printed metal oxide and Pt sensor electrodes have shown promising results but also clearly show the need for us to optimize the electrode and electrolyte compositions/morphologies and interfaces of these devices in order to demonstrate a sensitive, selective, and stable NO{sub x} sensor. Our previous methods and routes to preparing stable and reproducible mixed potential sensors - in bulk, tape cast, and thin film variants - need to be adapted as a necessary adjunct to address materials challenges resulting from the implementation of commercial manufacturing methods. We also modified the electrodes to demonstrate a NH{sub 3} sensor that can be used in conjunction with the NO{sub x} sensor for feedback control of emissions systems. Once desirable properties are achieved, we will work closely with potential customers in order to dynamometer and boiler test these devices. Ultimately, this will accurately gauge the level of readiness of mixed potential sensor technology for commercialization and eventual use of this important electrochemical technology.« less

Direct measurements of methane emissions from abandoned oil and gas wells in Pennsylvania.

PubMed

Kang, Mary; Kanno, Cynthia M; Reid, Matthew C; Zhang, Xin; Mauzerall, Denise L; Celia, Michael A; Chen, Yuheng; Onstott, Tullis C

2014-12-23

Abandoned oil and gas wells provide a potential pathway for subsurface migration and emissions of methane and other fluids to the atmosphere. Little is known about methane fluxes from the millions of abandoned wells that exist in the United States. Here, we report direct measurements of methane fluxes from abandoned oil and gas wells in Pennsylvania, using static flux chambers. A total of 42 and 52 direct measurements were made at wells and at locations near the wells ("controls") in forested, wetland, grassland, and river areas in July, August, October 2013 and January 2014, respectively. The mean methane flow rates at these well locations were 0.27 kg/d/well, and the mean methane flow rate at the control locations was 4.5 × 10(-6) kg/d/location. Three out of the 19 measured wells were high emitters that had methane flow rates that were three orders of magnitude larger than the median flow rate of 1.3 × 10(-3) kg/d/well. Assuming the mean flow rate found here is representative of all abandoned wells in Pennsylvania, we scaled the methane emissions to be 4-7% of estimated total anthropogenic methane emissions in Pennsylvania. The presence of ethane, propane, and n-butane, along with the methane isotopic composition, indicate that the emitted methane is predominantly of thermogenic origin. These measurements show that methane emissions from abandoned oil and gas wells can be significant. The research required to quantify these emissions nationally should be undertaken so they can be accurately described and included in greenhouse gas emissions inventories.

40 CFR 63.325 - Determination of equivalent emission control technology.

Code of Federal Regulations, 2010 CFR

2010-07-01

... control technology. 63.325 Section 63.325 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Determination of equivalent emission control technology. (a) Any person requesting that the use of certain... equivalent emission reductions: (1) Diagrams, as appropriate, illustrating the emission control technology...

Decadal changes in emissions of volatile organic compounds (VOCs) from on-road vehicles with intensified automobile pollution control: Case study in a busy urban tunnel in south China.

PubMed

Zhang, Yanli; Yang, Weiqiang; Simpson, Isobel; Huang, Xinyu; Yu, Jianzhen; Huang, Zhonghui; Wang, Zhaoyi; Zhang, Zhou; Liu, Di; Huang, Zuzhao; Wang, Yujun; Pei, Chenglei; Shao, Min; Blake, Donald R; Zheng, Junyu; Huang, Zhijiong; Wang, Xinming

2018-02-01

In the efforts at controlling automobile emissions, it is important to know in what extent air pollutants from on-road vehicles could be truly reduced. In 2014 we conducted tests in a heavily trafficked tunnel in south China to characterize emissions of volatile organic compounds (VOC) from on-road vehicle fleet and compared our results with those obtained in the same tunnel in 2004. Alkanes, aromatics, and alkenes had average emission factors (EFs) of 338, 63, and 42 mg km -1 in 2014 against that of 194, 129, and 160 mg km -1 in 2004, respectively. In 2014, LPG-related propane, n-butane and i-butane were the top three non-methane hydrocarbons (NMHCs) with EFs of 184 ± 21, 53 ± 6 and 31 ± 3 mg km -1 ; the gasoline evaporation marker i-pentane had an average EF of 17 ± 3 mg km -1 ; ethylene and propene were the top two alkenes with average EFs of 16 ± 1 and 9.7 ± 0.9 mg km -1 , respectively; isoprene had no direct emission from vehicles; toluene showed the highest EF of 11 ± 2 mg km -1 among the aromatics; and acetylene had an average EF of 7 ± 1 mg km -1 . While EFs of total NMHCs decreased only 9% from 493 ± 120 mg km -1 in 2004 to 449 ± 40 mg km -1 in 2014, their total ozone formation potential (OFP) decreased by 57% from 2.50 × 10 3  mg km -1 in 2004 to 1.10 × 10 3  mg km -1 in 2014, and their total secondary organic aerosol formation potential (SOAFP) decreased by 50% from 50 mg km -1 in 2004 to 25 mg km -1 in 2014. The large drop in ozone and SOA formation potentials could be explained by reduced emissions of reactive alkenes and aromatics, due largely to fuel transition from gasoline/diesel to LPG for taxis/buses and upgraded vehicle emission standards. Copyright © 2017 Elsevier Ltd. All rights reserved.

A unifying conceptual model for the environmental responses of isoprene emissions from plants.

PubMed

Morfopoulos, Catherine; Prentice, Iain C; Keenan, Trevor F; Friedlingstein, Pierre; Medlyn, Belinda E; Peñuelas, Josep; Possell, Malcolm

2013-11-01

Isoprene is the most important volatile organic compound emitted by land plants in terms of abundance and environmental effects. Controls on isoprene emission rates include light, temperature, water supply and CO2 concentration. A need to quantify these controls has long been recognized. There are already models that give realistic results, but they are complex, highly empirical and require separate responses to different drivers. This study sets out to find a simpler, unifying principle. A simple model is presented based on the idea of balancing demands for reducing power (derived from photosynthetic electron transport) in primary metabolism versus the secondary pathway that leads to the synthesis of isoprene. This model's ability to account for key features in a variety of experimental data sets is assessed. The model simultaneously predicts the fundamental responses observed in short-term experiments, namely: (1) the decoupling between carbon assimilation and isoprene emission; (2) a continued increase in isoprene emission with photosynthetically active radiation (PAR) at high PAR, after carbon assimilation has saturated; (3) a maximum of isoprene emission at low internal CO2 concentration (ci) and an asymptotic decline thereafter with increasing ci; (4) maintenance of high isoprene emissions when carbon assimilation is restricted by drought; and (5) a temperature optimum higher than that of photosynthesis, but lower than that of isoprene synthase activity. A simple model was used to test the hypothesis that reducing power available to the synthesis pathway for isoprene varies according to the extent to which the needs of carbon assimilation are satisfied. Despite its simplicity the model explains much in terms of the observed response of isoprene to external drivers as well as the observed decoupling between carbon assimilation and isoprene emission. The concept has the potential to improve global-scale modelling of vegetation isoprene emission.

The impact of municipal solid waste management on greenhouse gas emissions in the United States.

PubMed

Weitz, Keith A; Thorneloe, Susan A; Nishtala, Subba R; Yarkosky, Sherry; Zannes, Maria

2002-09-01

Technological advancements, environmental regulations, and emphasis on resource conservation and recovery have greatly reduced the environmental impacts of municipal solid waste (MSW) management, including emissions of greenhouse gases (GHGs). This study was conducted using a life-cycle methodology to track changes in GHG emissions during the past 25 years from the management of MSW in the United States. For the baseline year of 1974, MSW management consisted of limited recycling, combustion without energy recovery, and landfilling without gas collection or control. This was compared with data for 1980, 1990, and 1997, accounting for changes in MSW quantity, composition, management practices, and technology. Over time, the United States has moved toward increased recycling, composting, combustion (with energy recovery) and landfilling with gas recovery, control, and utilization. These changes were accounted for with historical data on MSW composition, quantities, management practices, and technological changes. Included in the analysis were the benefits of materials recycling and energy recovery to the extent that these displace virgin raw materials and fossil fuel electricity production, respectively. Carbon sinks associated with MSW management also were addressed. The results indicate that the MSW management actions taken by U.S. communities have significantly reduced potential GHG emissions despite an almost 2-fold increase in waste generation. GHG emissions from MSW management were estimated to be 36 million metric tons carbon equivalents (MMTCE) in 1974 and 8 MMTCE in 1997. If MSW were being managed today as it was in 1974, GHG emissions would be approximately 60 MMTCE.

Methane Emissions from Semi-natural, Drained and Re-wetted Peatlands in Germany

NASA Astrophysics Data System (ADS)

Tiemeyer, B.; Bechtold, M.; Albiac Borraz, E.; Augustin, J.; Drösler, M.; Beetz, S.; Beyer, C.; Eickenscheidt, T.; Fiedler, S.; Förster, C.; Giebels, M.; Glatzel, S.; Heinichen, J.; Höper, H.; Leiber-Sauheitl, K.; Peichl-Brak, M.; Rosskopf, N.; Sommer, M.; Zeitz, J.; Freibauer, A.

2014-12-01

Drained peatlands contribute around 5% to the total German greenhouse gas emissions. While these areas are hotspots for carbon dioxide (CO2) and nitrous oxide (N2O) emissions, some re-wetted peatlands may emit large amounts of methane (CH4). To quantify the GHG emission reductions achieved by the re-wetting of peatlands, the reduced CO2 emissions and the potential CH4fluxes need to be balanced. We synthesized methane flux data from 14 peatlands with 122 sites. At each site, methane fluxes were measured for one to three years with static chambers. The sites comprise arable land, intensive and extensive grassland, forest and peat mining areas as well as semi-natural and re-wetted peatlands on both bog peat, fen peat and other soils rich in organic carbon. Besides the groundwater table we consider further potential drivers for the CH4fluxes such as soil properties (carbon, nitrogen, pH, and physical properties), climatic parameters, land use, and vegetation composition. Annual methane fluxes ranged from low uptake rates (around -1 g CH4-C m² a-1) to very high emissions (> 200 g CH4-C m² a-1). Intensively drained sites showed very low emissions, while for annual mean water levels higher than 5-10 cm below ground, elevated emissions of more than 20 g CH4-C may occur. At some re-wetted sites CH4 emissions of more than 100 g CH4-C m² a-1 were measured, which roughly equal the Global Warming Potential of the CO2-emissions from intensively drained agricultural sites. These high fluxes were probably caused by a combination of nutrient-rich conditions, the dieback of poorly adapted plants and a fast accumulation of organic sediments. However, this was the exception and not the rule even for very wet re-wetted sites. Achieving a model efficiency of 0.72 during cross-validation, a boosted regression tree (BRT) model was well able to describe logarithmic CH4-fluxes. Groundwater level, biotope type, soil nitrogen content, and ponding duration during summer were the most important controls. Combining the BRT model with soil, land use, and groundwater table maps as well as weather data, methane fluxes were upscaled for Germany.

Radio-Frequency-Controlled Urea Dosing for NH₃-SCR Catalysts: NH₃ Storage Influence to Catalyst Performance under Transient Conditions.

PubMed

Dietrich, Markus; Hagen, Gunter; Reitmeier, Willibald; Burger, Katharina; Hien, Markus; Grass, Philippe; Kubinski, David; Visser, Jaco; Moos, Ralf

2017-11-28

Current developments in exhaust gas aftertreatment led to a huge mistrust in diesel driven passenger cars due to their NO x emissions being too high. The selective catalytic reduction (SCR) with ammonia (NH₃) as reducing agent is the only approach today with the capability to meet upcoming emission limits. Therefore, the radio-frequency-based (RF) catalyst state determination to monitor the NH₃ loading on SCR catalysts has a huge potential in emission reduction. Recent work on this topic proved the basic capability of this technique under realistic conditions on an engine test bench. In these studies, an RF system calibration for the serial type SCR catalyst Cu-SSZ-13 was developed and different approaches for a temperature dependent NH₃ storage were determined. This paper continues this work and uses a fully calibrated RF-SCR system under transient conditions to compare different directly measured and controlled NH₃ storage levels, and NH₃ target curves. It could be clearly demonstrated that the right NH₃ target curve, together with a direct control on the desired level by the RF system, is able to operate the SCR system with the maximum possible NO x conversion efficiency and without NH₃ slip.

Deterministic control of the emission from light sources in 1D nanoporous photonic crystals (Conference Presentation)

NASA Astrophysics Data System (ADS)

Galisteo-López, Juan F.

2017-02-01

Controlling the emission of a light source demands acting on its local photonic environment via the local density of states (LDOS). Approaches to exert such control on large scale samples, commonly relying on self-assembly methods, usually lack from a precise positioning of the emitter within the material. Alternatively expensive and time consuming techniques can be used to produce samples of small dimensions where a deterministic control on emitter position can be achieved. In this work we present a full solution process approach to fabricate photonic architectures containing nano-emitters which position can be controlled with nanometer precision over squared milimiter regions. By a combination of spin and dip coating we fabricate one-dimensional (1D) nanoporous photonic crystals, which potential in different fields such as photovoltaics or sensing has been previously reported, containing monolayers of luminescent polymeric nanospheres. We demonstrate how, by modifying the position of the emitters within the photonic crystal, their emission properties (photoluminescence intensity and angular distribution) can be deterministically modified. Further, the nano-emitters can be used as a probe to study the LDOS distribution within these systems with a spatial resolution of 25 nm (provided by the probe size) carrying out macroscopic measurements over squared milimiter regions. Routes to enhance light-matter interaction in this kind of systems by combining them with metallic surfaces are finally discussed.

Responses of Soil CO2 Fluxes to Short-Term Experimental Warming in Alpine Steppe Ecosystem, Northern Tibet

PubMed Central

Lu, Xuyang; Fan, Jihui; Yan, Yan; Wang, Xiaodan

2013-01-01

Soil carbon dioxide (CO2) emission is one of the largest fluxes in the global carbon cycle. Therefore small changes in the size of this flux can have a large effect on atmospheric CO2 concentrations and potentially constitute a powerful positive feedback to the climate system. Soil CO2 fluxes in the alpine steppe ecosystem of Northern Tibet and their responses to short-term experimental warming were investigated during the growing season in 2011. The results showed that the total soil CO2 emission fluxes during the entire growing season were 55.82 and 104.31 g C m-2 for the control and warming plots, respectively. Thus, the soil CO2 emission fluxes increased 86.86% with the air temperature increasing 3.74°C. Moreover, the temperature sensitivity coefficient (Q 10) of the control and warming plots were 2.10 and 1.41, respectively. The soil temperature and soil moisture could partially explain the temporal variations of soil CO2 fluxes. The relationship between the temporal variation of soil CO2 fluxes and the soil temperature can be described by exponential equation. These results suggest that warming significantly promoted soil CO2 emission in the alpine steppe ecosystem of Northern Tibet and indicate that this alpine ecosystem is very vulnerable to climate change. In addition, soil temperature and soil moisture are the key factors that controls soil organic matter decomposition and soil CO2 emission, but temperature sensitivity significantly decreases due to the rise in temperature. PMID:23536854

Responses of soil CO2 fluxes to short-term experimental warming in alpine steppe ecosystem, Northern Tibet.

PubMed

Lu, Xuyang; Fan, Jihui; Yan, Yan; Wang, Xiaodan

2013-01-01

Soil carbon dioxide (CO2) emission is one of the largest fluxes in the global carbon cycle. Therefore small changes in the size of this flux can have a large effect on atmospheric CO2 concentrations and potentially constitute a powerful positive feedback to the climate system. Soil CO2 fluxes in the alpine steppe ecosystem of Northern Tibet and their responses to short-term experimental warming were investigated during the growing season in 2011. The results showed that the total soil CO2 emission fluxes during the entire growing season were 55.82 and 104.31 g C m(-2) for the control and warming plots, respectively. Thus, the soil CO2 emission fluxes increased 86.86% with the air temperature increasing 3.74°C. Moreover, the temperature sensitivity coefficient (Q 10) of the control and warming plots were 2.10 and 1.41, respectively. The soil temperature and soil moisture could partially explain the temporal variations of soil CO2 fluxes. The relationship between the temporal variation of soil CO2 fluxes and the soil temperature can be described by exponential equation. These results suggest that warming significantly promoted soil CO2 emission in the alpine steppe ecosystem of Northern Tibet and indicate that this alpine ecosystem is very vulnerable to climate change. In addition, soil temperature and soil moisture are the key factors that controls soil organic matter decomposition and soil CO2 emission, but temperature sensitivity significantly decreases due to the rise in temperature.

Adsorbents for capturing mercury in coal-fired boiler flue gas.

PubMed

Yang, Hongqun; Xu, Zhenghe; Fan, Maohong; Bland, Alan E; Judkins, Roddie R

2007-07-19

This paper reviews recent advances in the research and development of sorbents used to capture mercury from coal-fired utility boiler flue gas. Mercury emissions are the source of serious health concerns. Worldwide mercury emissions from human activities are estimated to be 1000 to 6000 t/annum. Mercury emissions from coal-fired power plants are believed to be the largest source of anthropogenic mercury emissions. Mercury emissions from coal-fired utility boilers vary in total amount and speciation, depending on coal types, boiler operating conditions, and configurations of air pollution control devices (APCDs). The APCDs, such as fabric filter (FF) bag house, electrostatic precipitator (ESP), and wet flue gas desulfurization (FGD), can remove some particulate-bound and oxidized forms of mercury. Elemental mercury often escapes from these devices. Activated carbon injection upstream of a particulate control device has been shown to have the best potential to remove both elemental and oxidized mercury from the flue gas. For this paper, NORIT FGD activated carbon was extensively studied for its mercury adsorption behavior. Results from bench-, pilot- and field-scale studies, mercury adsorption by coal chars, and a case of lignite-burned mercury control were reviewed. Studies of brominated carbon, sulfur-impregnated carbon and chloride-impregnated carbon were also reviewed. Carbon substitutes, such as calcium sorbents, petroleum coke, zeolites and fly ash were analyzed for their mercury-adsorption performance. At this time, brominated activated carbon appears to be the best-performing mercury sorbent. A non-injection regenerable sorbent technology is briefly introduced herein, and the issue of mercury leachability is briefly covered. Future research directions are suggested.

Impact of Airspace Charges on Transatlantic Aircraft Trajectories

NASA Technical Reports Server (NTRS)

Sridhar, Banavar; Ng, Hok K.; Linke, Florian; Chen, Neil Y.

2015-01-01

Aircraft flying over the airspace of different countries are subject to over-flight charges. These charges vary from country to country. Airspace charges, while necessary to support the communication, navigation and surveillance services, may lead to aircraft flying routes longer than wind-optimal routes and produce additional carbon dioxide and other gaseous emissions. This paper develops an optimal route between city pairs by modifying the cost function to include an airspace cost whenever an aircraft flies through a controlled airspace without landing or departing from that airspace. It is assumed that the aircraft will fly the trajectory at a constant cruise altitude and constant speed. The computationally efficient optimal trajectory is derived by solving a non-linear optimal control problem. The operational strategies investigated in this study for minimizing aircraft fuel burn and emissions include flying fuel-optimal routes and flying cost-optimal routes that may completely or partially reduce airspace charges en route. The results in this paper use traffic data for transatlantic flights during July 2012. The mean daily savings in over-flight charges, fuel cost and total operation cost during the period are 17.6 percent, 1.6 percent, and 2.4 percent respectively, along the cost- optimal trajectories. The transatlantic flights can potentially save $600,000 in fuel cost plus $360,000 in over-flight charges daily by flying the cost-optimal trajectories. In addition, the aircraft emissions can be potentially reduced by 2,070 metric tons each day. The airport pairs and airspace regions that have the highest potential impacts due to airspace charges are identified for possible reduction of fuel burn and aircraft emissions for the transatlantic flights. The results in the paper show that the impact of the variation in fuel price on the optimal routes is to reduce the difference between wind-optimal and cost-optimal routes as the fuel price increases. The additional fuel consumption is quantified using the 30 percent variation in fuel prices during March 2014 to March 2015.

Improved attribution of climate forcing to emissions by pollutant and sector

NASA Astrophysics Data System (ADS)

Shindell, D. T.

2009-12-01

Evaluating multi-component climate change mitigation strategies requires knowledge of the diverse direct and indirect effects of emissions. Methane, ozone and aerosols are linked through atmospheric chemistry so that emissions of a single pollutant can affect several species. I will show new calculations of atmospheric composition changes, radiative forcing, and the global warming potential (GWP) for increased emissions of tropospheric ozone and aerosol precursors in a coupled composition-climate model. The results demonstrate that gas-aerosol interactions substantially alter the relative importance of the various emissions, suggesting revisions to the GWPs used in international carbon trading. Additionally, I will present results showing how the net climate impact of particular activities depends strongly upon non-CO2 forcing agents for some sectors. These results will be highlighted by discussing the interplay between air quality emissions controls and climate for the case of emissions from coal-fired power plants. The changing balance between CO2 and air quality pollutants from coal plants may have contributed to the 20th century spatial and temporal patterns of climate change, and is likely to continue to do so as more and more plants are constructed in Asia.

Greenhouse Gas Emissions from Reservoir Water Surfaces: A ...

EPA Pesticide Factsheets

Collectively, reservoirs are an important anthropogenic source of greenhouse gases (GHGs) to the atmosphere. Attempts to model reservoir GHG fluxes, however, have been limited by inconsistencies in methodological approaches and data availability. An increase in the number of published reservoir GHG flux estimates during the last 15 years warrants a comprehensive analysis of the magnitude and potential controls on these fluxes. Here we synthesize worldwide reservoir CH4, CO2, and N2O emission data and estimate that GHG emissions from reservoirs account for 80.2 Tmol CO2 equivalents yr-1, thus constituting approximately 5% of anthropogenic radiative forcing. The majority (93%) of these emissions are from CH4, and mainly in the form of bubbles. While age and latitude have historically been linked to reservoir GHG emissions, we found that factors related to reservoir nutrient status and rainfall were better predictors. In particular, nutrient-rich eutrophic reservoirs were found to have an order of magnitude higher per-area CH4 fluxes, on average, than their nutrient-poor oligotrophic counterparts. Therefore, management measures to reduce reservoir eutrophication may result in an important co-benefit, the reduction of GHG emissions to the atmosphere. Greenhouse gas emissions (GHG)

40 CFR 1045.801 - What definitions apply to this part?

Code of Federal Regulations, 2011 CFR

2011-07-01

... emission control device means any element of design that senses temperature, motive speed, engine RPM... of design that controls or reduces the emissions of regulated pollutants from an engine. Emission... POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION MARINE ENGINES AND VESSELS...

40 CFR 1045.801 - What definitions apply to this part?

Code of Federal Regulations, 2014 CFR

2014-07-01

... emission control device means any element of design that senses temperature, motive speed, engine RPM... of design that controls or reduces the emissions of regulated pollutants from an engine. Emission... POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION MARINE ENGINES AND VESSELS...

40 CFR 1045.801 - What definitions apply to this part?

Code of Federal Regulations, 2012 CFR

2012-07-01

... emission control device means any element of design that senses temperature, motive speed, engine RPM... of design that controls or reduces the emissions of regulated pollutants from an engine. Emission... POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION MARINE ENGINES AND VESSELS...

40 CFR 1045.801 - What definitions apply to this part?

Code of Federal Regulations, 2010 CFR

2010-07-01

... emission control device means any element of design that senses temperature, motive speed, engine RPM... of design that controls or reduces the emissions of regulated pollutants from an engine. Emission... POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION MARINE ENGINES AND VESSELS...

An aluminium nitride light-emitting diode with a wavelength of 210 nanometres.

PubMed

Taniyasu, Yoshitaka; Kasu, Makoto; Makimoto, Toshiki

2006-05-18

Compact high-efficiency ultraviolet solid-state light sources--such as light-emitting diodes (LEDs) and laser diodes--are of considerable technological interest as alternatives to large, toxic, low-efficiency gas lasers and mercury lamps. Microelectronic fabrication technologies and the environmental sciences both require light sources with shorter emission wavelengths: the former for improved resolution in photolithography and the latter for sensors that can detect minute hazardous particles. In addition, ultraviolet solid-state light sources are also attracting attention for potential applications in high-density optical data storage, biomedical research, water and air purification, and sterilization. Wide-bandgap materials, such as diamond and III-V nitride semiconductors (GaN, AlGaN and AlN; refs 3-10), are potential materials for ultraviolet LEDs and laser diodes, but suffer from difficulties in controlling electrical conduction. Here we report the successful control of both n-type and p-type doping in aluminium nitride (AlN), which has a very wide direct bandgap of 6 eV. This doping strategy allows us to develop an AlN PIN (p-type/intrinsic/n-type) homojunction LED with an emission wavelength of 210 nm, which is the shortest reported to date for any kind of LED. The emission is attributed to an exciton transition, and represents an important step towards achieving exciton-related light-emitting devices as well as replacing gas light sources with solid-state light sources.

Variability in methane emissions from West Siberia's shallow boreal lakes on a regional scale and its environmental controls

NASA Astrophysics Data System (ADS)

Sabrekov, Aleksandr F.; Runkle, Benjamin R. K.; Glagolev, Mikhail V.; Terentieva, Irina E.; Stepanenko, Victor M.; Kotsyurbenko, Oleg R.; Maksyutov, Shamil S.; Pokrovsky, Oleg S.

2017-08-01

Small lakes represent an important source of atmospheric CH4 from northern wetlands. However, spatiotemporal variations in flux magnitudes and the lack of knowledge about their main environmental controls contribute large uncertainty into the global CH4 budget. In this study, we measured methane fluxes from small lakes using chambers and bubble traps. Field investigations were carried out in July-August 2014 within the West Siberian middle and southern taiga zones. The average and median of measured methane chamber fluxes were 0.32 and 0.30 mgCH4 m-2 h-1 for middle taiga lakes and 8.6 and 4.1 mgCH4 m-2 h-1 for southern taiga lakes, respectively. Pronounced flux variability was found during measurements on individual lakes, between individual lakes and between zones. To analyze these differences and the influences of environmental controls, we developed a new dynamic process-based model. It shows good performance with emission rates from the southern taiga lakes and poor performance for individual lakes in the middle taiga region. The model shows that, in addition to well-known controls such as temperature, pH and lake depth, there are significant variations in the maximal methane production potential between these climatic zones. In addition, the model shows that variations in gas-filled pore space in lake sediments are capable of controlling the total methane emissions from individual lakes. The CH4 emissions exhibited distinct zonal differences not only in absolute values but also in their probability density functions: the middle taiga lake fluxes were best described by a lognormal distribution while the southern taiga lakes followed a power-law distribution. The latter suggests applicability of self-organized criticality theory for methane emissions from the southern taiga zone, which could help to explain the strong variability within individual lakes.

Assessing the co-benefits of greenhouse gas reduction: health benefits of particulate matter related inspection and maintenance programs in Bangkok, Thailand.

PubMed

Li, Ying; Crawford-Brown, Douglas J

2011-04-15

Since the 1990s, the capital city of Thailand, Bangkok has been suffering from severe ambient particulate matter (PM) pollution mainly attributable to its wide use of diesel-fueled vehicles and motorcycles with poor emission performance. While the Thai government strives to reduce emissions from transportation through enforcing policy measures, the link between specific control policies and associated health impacts is inadequately studied. This link is especially important in exploring the co-benefits of greenhouse gas emissions reductions, which often brings reduction in other pollutants such as PM. This paper quantifies the health benefits potentially achieved by the new PM-related I/M programs targeting all diesel vehicles and motorcycles in the Bangkok Metropolitan Area (BMA). The benefits are estimated by using a framework that integrates policy scenario development, exposure assessment, exposure-response assessment and economic valuation. The results indicate that the total health damage due to the year 2000 PM emissions from vehicles in the BMA was equivalent to 2.4% of Thailand's GDP. Under the business-as-usual (BAU) scenario, total vehicular PM emissions in the BMA will increase considerably over time due to the rapid growth in vehicle population, even if the fleet average emission rates are projected to decrease over time as the result of participation of Thailand in post-Copenhagen climate change strategies. By 2015, the total health damage is estimated to increase by 2.5 times relative to the year 2000. However, control policies targeting PM emissions from automobiles, such as the PM-oriented I/M programs, could yield substantial health benefits relative to the BAU scenario, and serve as co-benefits of greenhouse gas control strategies. Despite uncertainty associated with the key assumptions used to estimate benefits, we find that with a high level confidence, the I/M programs will produce health benefits whose economic impacts considerably outweigh the expenditures on policy implementation. Copyright © 2011 Elsevier B.V. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2016-05-01

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

The long-run effects of economic, demographic, and political indices on actual and potential CO2 emissions.

PubMed

Adom, Philip Kofi; Kwakwa, Paul Adjei; Amankwaa, Afua

2018-07-15

This study examines the long-run drivers of potential and actual CO 2 emissions in Ghana, a sub-Saharan Africa country. The use of the former helps address the reverse causality problem and capture the true long-run effects. The Stock-Watson dynamic OLS is used with data from 1970 to 2014. The result shows that potential CO 2 emissions improve model efficiency. Income (except in "other sector") and financial development (except in manufacturing and construction sector) have compelling positive and negative effects on actual and potential CO 2 emissions, respectively. A higher price (oil and electricity) reduces actual and potential CO 2 emissions, but electricity price is more vital in residential, buildings and commercial and public services sector, while oil price is crucial in the transport sector. Democracy lowers actual and potential CO 2 emissions in the aggregate (insignificant) and transport sectors but raises it in the manufacturing and construction sector. The effect is, however, inconsistent for the remaining sectors. Urbanization raises aggregate actual and potential CO 2 emissions, but the effect is inconsistent for the transport sector. The findings have important implications for policy formulation. Copyright © 2018 Elsevier Ltd. All rights reserved.

40 CFR 1060.230 - How do I select emission families?

Code of Federal Regulations, 2011 CFR

2011-07-01

... family if they are the same in all the following aspects: (1) Emission control strategy and design. (2... POLLUTION CONTROLS CONTROL OF EVAPORATIVE EMISSIONS FROM NEW AND IN-USE NONROAD AND STATIONARY EQUIPMENT... emission characteristics throughout their useful life. (b) Group fuel lines into the same emission family...

40 CFR 76.10 - Alternative emission limitations.

Code of Federal Regulations, 2013 CFR

2013-07-01

...; and (ii) The installed NOX emission control system has been designed to meet the applicable emission... that the unit and NOX emission control system were operated in accordance with the bid and design specifications on which the design of the NOX emission control system was based; and (C) Unit operating data as...

40 CFR 1060.230 - How do I select emission families?

Code of Federal Regulations, 2013 CFR

2013-07-01

... family if they are the same in all the following aspects: (1) Emission control strategy and design. (2... POLLUTION CONTROLS CONTROL OF EVAPORATIVE EMISSIONS FROM NEW AND IN-USE NONROAD AND STATIONARY EQUIPMENT... emission characteristics throughout their useful life. (b) Group fuel lines into the same emission family...

40 CFR 1060.230 - How do I select emission families?

Code of Federal Regulations, 2012 CFR

2012-07-01

... family if they are the same in all the following aspects: (1) Emission control strategy and design. (2... POLLUTION CONTROLS CONTROL OF EVAPORATIVE EMISSIONS FROM NEW AND IN-USE NONROAD AND STATIONARY EQUIPMENT... emission characteristics throughout their useful life. (b) Group fuel lines into the same emission family...

40 CFR 76.10 - Alternative emission limitations.

Code of Federal Regulations, 2010 CFR

2010-07-01

...; and (ii) The installed NOX emission control system has been designed to meet the applicable emission... that the unit and NOX emission control system were operated in accordance with the bid and design specifications on which the design of the NOX emission control system was based; and (C) Unit operating data as...

40 CFR 1060.230 - How do I select emission families?

Code of Federal Regulations, 2010 CFR

2010-07-01

... family if they are the same in all the following aspects: (1) Emission control strategy and design. (2... POLLUTION CONTROLS CONTROL OF EVAPORATIVE EMISSIONS FROM NEW AND IN-USE NONROAD AND STATIONARY EQUIPMENT... emission characteristics throughout their useful life. (b) Group fuel lines into the same emission family...

40 CFR 1060.230 - How do I select emission families?

Code of Federal Regulations, 2014 CFR

2014-07-01

... family if they are the same in all the following aspects: (1) Emission control strategy and design. (2... POLLUTION CONTROLS CONTROL OF EVAPORATIVE EMISSIONS FROM NEW AND IN-USE NONROAD AND STATIONARY EQUIPMENT... emission characteristics throughout their useful life. (b) Group fuel lines into the same emission family...

Hydrocarbon emission fingerprints from contemporary vehicle/engine technologies with conventional and new fuels

NASA Astrophysics Data System (ADS)

Montero, Larisse; Duane, Matthew; Manfredi, Urbano; Astorga, Covadonga; Martini, Giorgio; Carriero, Massimo; Krasenbrink, Alois; Larsen, B. R.

2010-06-01

The present paper presents results from the analysis of 29 individual C 2-C 9 hydrocarbons (HCs) specified in the European Commission Ozone Directive. The 29 HCs are measured in exhaust from common, contemporary vehicle/engine/fuel technologies for which very little or no data is available in the literature. The obtained HC emission fingerprints are compared with fingerprints deriving from technologies that are being phased out in Europe. Based on the total of 138 emission tests, thirteen type-specific fingerprints are extracted (Mean ± SD percentage contributions from individual HCs to the total mass of the 29 HCs), essential for receptor modelling source apportionment. The different types represent exhaust from Euro3 and Euro4 light-duty (LD) diesel and petrol-vehicles, Euro3 heavy-duty (HD) diesel exhaust, and exhaust from 2-stroke preEuro, Euro1 and Euro2 mopeds. The fuels comprise liquefied petroleum gas, petrol/ethanol blends (0-85% ethanol), and mineral diesel in various blends (0-100%) with fatty acid methyl esters, rapeseed methyl esters palm oil methyl esters, soybean oil methyl or sunflower oil methyl esters. Type-specific tracer compounds (markers) are identified for the various vehicle/engine/fuel technologies. An important finding is an insignificant effect on the HC fingerprints of varying the test driving cycle, indicating that combining HC fingerprints from different emission studies for receptor modelling purposes would be a robust approach. The obtained results are discussed in the context of atmospheric ozone formation and health implications from emissions (mg km -1 for LD and mopeds and mg kW h -1 for HD, all normalised to fuel consumption: mg dm -3 fuel) of the harmful HCs, benzene and 1,3-butadiene. Another important finding is a strong linear correlation of the regulated "total" hydrocarbon emissions (tot-HC) with the ozone formation potential of the 29 HCs (ΣPO 3 = (1.66 ± 0.04) × tot-RH; r2 = 0.93). Tot-HC is routinely monitored in emission control laboratories, whereas C 2-C 9 are not. The revealed strong correlations broadens the usability of data from vehicle emission control laboratories and facilitates the comparison of the ozone formation potential of HCs in exhaust from of old and new vehicle/engine/fuel technologies.

40 CFR 1060.101 - What evaporative emission requirements apply under this part?

Code of Federal Regulations, 2010 CFR

2010-07-01

.... (c) Section 1060.104 describes running loss emission control requirements for fuel systems. (d... AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EVAPORATIVE EMISSIONS FROM NEW AND IN-USE NONROAD... related requirements as follows: (a) Section 1060.102 describes permeation emission control requirements...

Global Analysis, Interpretation, and Modelling: First Science Conference

NASA Technical Reports Server (NTRS)

Sahagian, Dork

1995-01-01

Topics considered include: Biomass of termites and their emissions of methane and carbon dioxide - A global database; Carbon isotope discrimination during photosynthesis and the isotope ratio of respired CO2 in boreal forest ecosystems; Estimation of methane emission from rice paddies in mainland China; Climate and nitrogen controls on the geography and timescales of terrestrial biogeochemical cycling; Potential role of vegetation feedback in the climate sensitivity of high-latitude regions - A case study at 6000 years B.P.; Interannual variation of carbon exchange fluxes in terrestrial ecosystems; and Variations in modeled atmospheric transport of carbon dioxide and the consequences for CO2 inversions.

The potential for land sparing to offset greenhouse gas emissions from agriculture

NASA Astrophysics Data System (ADS)

Lamb, Anthony; Green, Rhys; Bateman, Ian; Broadmeadow, Mark; Bruce, Toby; Burney, Jennifer; Carey, Pete; Chadwick, David; Crane, Ellie; Field, Rob; Goulding, Keith; Griffiths, Howard; Hastings, Astley; Kasoar, Tim; Kindred, Daniel; Phalan, Ben; Pickett, John; Smith, Pete; Wall, Eileen; Zu Ermgassen, Erasmus K. H. J.; Balmford, Andrew

2016-05-01

Greenhouse gas emissions from global agriculture are increasing at around 1% per annum, yet substantial cuts in emissions are needed across all sectors. The challenge of reducing agricultural emissions is particularly acute, because the reductions achievable by changing farming practices are limited and are hampered by rapidly rising food demand. Here we assess the technical mitigation potential offered by land sparing--increasing agricultural yields, reducing farmland area and actively restoring natural habitats on the land spared. Restored habitats can sequester carbon and can offset emissions from agriculture. Using the UK as an example, we estimate net emissions in 2050 under a range of future agricultural scenarios. We find that a land-sparing strategy has the technical potential to achieve significant reductions in net emissions from agriculture and land-use change. Coupling land sparing with demand-side strategies to reduce meat consumption and food waste can further increase the technical mitigation potential--however, economic and implementation considerations might limit the degree to which this technical potential could be realized in practice.

Diacetyl emissions and airborne dust from butter flavorings used in microwave popcorn production.

PubMed

Boylstein, Randy; Piacitelli, Chris; Grote, Ardith; Kanwal, Richard; Kullman, Greg; Kreiss, Kathleen

2006-10-01

In microwave popcorn workers, exposure to butter flavorings has been associated with fixed obstructive lung disease resembling bronchiolitis obliterans. Inhalation toxicology studies have shown severe respiratory effects in rats exposed to vapors from a paste butter flavoring, and to diacetyl, a diketone found in most butter flavorings. To gain a better understanding of worker exposures, we assessed diacetyl emissions and airborne dust levels from butter flavorings used by several microwave popcorn manufacturing companies. We heated bulk samples of 40 different butter flavorings (liquids, pastes, and powders) to approximately 50 degrees C and used gas chromatography, with a mass selective detector, to measure the relative abundance of volatile organic compounds emitted. Air sampling was conducted for diacetyl and for total and respirable dust during the mixing of powder, liquid, or paste flavorings with heated soybean oil at a microwave popcorn plant. To further examine the potential for respiratory exposures to powders, we measured dust generated during different simulated methods of manual handling of several powder butter flavorings. Powder flavorings were found to give off much lower diacetyl emissions than pastes or liquids. The mean diacetyl emissions from liquids and pastes were 64 and 26 times larger, respectively, than the mean of diacetyl emissions from powders. The median diacetyl emissions from liquids and pastes were 364 and 72 times larger, respectively, than the median of diacetyl emissions from powders. Fourteen of 16 powders had diacetyl emissions that were lower than the diacetyl emissions from any liquid flavoring and from most paste flavorings. However, simulated handling of powder flavorings showed that a substantial amount of the airborne dust generated was of respirable size and could thus pose its own respiratory hazard. Companies that use butter flavorings should consider substituting flavorings with lower diacetyl emissions and the use of ventilation and enclosure engineering controls to minimize exposures. Until controls are fully implemented, companies should institute mandatory respiratory protection for all exposed workers.

NREL Fuels and Engines Research: Maximizing Vehicle Efficiency and

Science.gov Websites

Laboratory, we analyze the effects of fuel chemistry on ignition and the potential emissions impacts. Our lab research. It can be used to investigate fuel chemistry effects on current and near-term engine technology , independent control allows for deeper interrogation of fuel effects on future-generation engine strategies

Anaerobic soil disinfestation impact on soil nutrients dynamics and nitrous oxide emissions in fresh-market tomato

USDA-ARS?s Scientific Manuscript database

Anaerobic soil disinfestation (ASD) is proposed as a pre-plant, non-chemical soil disinfestation technique to control several soilborne phytosanitary issues. Limited information is available on the impact of ASD on soil fertility, plant growth, and potential nutrient loss. The objectives of the curr...

Control of Groundwater Pollution from Animal Feeding Operations: A Farm-Level Dynamic Model for Policy Analysis

NASA Astrophysics Data System (ADS)

Wang, J.; Baerenklau, K.

2012-12-01

Consolidation in livestock production generates higher farm incomes due to economies of scale, but it also brings waste disposal problems. Over-application of animal waste on adjacent land produces adverse environmental and health effects, including groundwater nitrate pollution. The situation is particularly noticeable in California. In respond to this increasingly severe problem, EPA published a type of command-and-control regulation for concentrated animal feeding operations (CAFOs) in 2003. The key component of the regulation is its nutrient management plans (NMPs), which intend to limit the land application rates of animal waste. Although previous studies provide a full perspective on potential economic impacts for CAFOs to meet nutrient standards, their models are static and fail to reflect changes in management practices other than spreading manure on additional land and changing cropping patterns. We develop a dynamic environmental-economic modeling framework for representative CAFOs. The framework incorporates four models (i.e., animal model, crop model, hydrologic model, and economic model) that include various components such as herd management, manure handling system, crop rotation, water sources, irrigation system, waste disposal options, and pollutant emissions. We also include the dynamics of soil characteristics in the rootzone as well as the spatial heterogeneity of the irrigation system. The operator maximizes discounted total farm profit over multiple periods subject to environmental regulations. Decision rules from the dynamic optimization problem demonstrate best management practices for CAFOs to improve their economic and environmental performance. Results from policy simulations suggest that direct quantity restrictions of emission or incentive-based emission policies are much more cost-effective than the standard approach of limiting the amount of animal waste that may be applied to fields (as shown in the figure below); reason being, policies targeting intermediate pollution and final pollution create incentives for the operator to examine the effects of other management practices to reduce pollution in addition to controlling the polluting inputs. Incentive-based mechanisms are slightly more cost-effective than quantity controls when seasonal emissions fluctuate. Our approach demonstrates the importance of taking into account the spatial & temporal dynamics in the rootzone and the integrated effects of water, nitrogen, and salinity on crop yield and nitrate emissions. It also highlights the significant role the environment can play in pollution control and the potential benefits from designing policies that acknowledge this role.oss of Total Net Farm Income Under Alternative Policies

Mitochondrial uncoupling in skeletal muscle by UCP1 augments energy expenditure and glutathione content while mitigating ROS production.

PubMed

Adjeitey, Cyril Nii-Klu; Mailloux, Ryan J; Dekemp, Robert A; Harper, Mary-Ellen

2013-08-01

Enhancement of proton leaks in muscle tissue represents a potential target for obesity treatment. In this study, we examined the bioenergetic and physiological implications of increased proton leak in skeletal muscle. To induce muscle-specific increases in proton leak, we used mice that selectively express uncoupling protein-1 (UCP1) in skeletal muscle tissue. UCP1 expression in muscle mitochondria was ∼13% of levels in brown adipose tissue (BAT) mitochondria and caused increased GDP-sensitive proton leak. This was associated with an increase in whole body energy expenditure and a decrease in white adipose tissue content. Muscle UCP1 activity had divergent effects on mitochondrial ROS emission and glutathione levels compared with BAT. UCP1 in muscle increased total mitochondrial glutathione levels ∼7.6 fold. Intriguingly, unlike in BAT mitochondria, leak through UCP1 in muscle controlled mitochondrial ROS emission. Inhibition of UCP1 with GDP in muscle mitochondria increased ROS emission ∼2.8-fold relative to WT muscle mitochondria. GDP had no impact on ROS emission from BAT mitochondria from either genotype. Collectively, these findings indicate that selective induction of UCP1-mediated proton leak in muscle can increase whole body energy expenditure and decrease adiposity. Moreover, ectopic UCP1 expression in skeletal muscle can control mitochondrial ROS emission, while it apparently plays no such role in its endogenous tissue, brown fat.

Mitochondrial uncoupling in skeletal muscle by UCP1 augments energy expenditure and glutathione content while mitigating ROS production

PubMed Central

Adjeitey, Cyril Nii-Klu; Mailloux, Ryan J.; deKemp, Robert A.

2013-01-01

Enhancement of proton leaks in muscle tissue represents a potential target for obesity treatment. In this study, we examined the bioenergetic and physiological implications of increased proton leak in skeletal muscle. To induce muscle-specific increases in proton leak, we used mice that selectively express uncoupling protein-1 (UCP1) in skeletal muscle tissue. UCP1 expression in muscle mitochondria was ∼13% of levels in brown adipose tissue (BAT) mitochondria and caused increased GDP-sensitive proton leak. This was associated with an increase in whole body energy expenditure and a decrease in white adipose tissue content. Muscle UCP1 activity had divergent effects on mitochondrial ROS emission and glutathione levels compared with BAT. UCP1 in muscle increased total mitochondrial glutathione levels ∼7.6 fold. Intriguingly, unlike in BAT mitochondria, leak through UCP1 in muscle controlled mitochondrial ROS emission. Inhibition of UCP1 with GDP in muscle mitochondria increased ROS emission ∼2.8-fold relative to WT muscle mitochondria. GDP had no impact on ROS emission from BAT mitochondria from either genotype. Collectively, these findings indicate that selective induction of UCP1-mediated proton leak in muscle can increase whole body energy expenditure and decrease adiposity. Moreover, ectopic UCP1 expression in skeletal muscle can control mitochondrial ROS emission, while it apparently plays no such role in its endogenous tissue, brown fat. PMID:23757405

Co-development of climate smart flooded rice farming systems

NASA Astrophysics Data System (ADS)

de Neergaard, Andreas; Stoumann Jensen, Lars; Ly, Proyuth; Pandey, Arjun; Duong Vu, Quynh; Tariq, Azeem; Islam, Syed; van Groenigen, Jan Willem; Sander, Bjoern Ole; de Tourdonnet, Stephane; Van Mai, Trinh; Wassmann, Reiner

2017-04-01

Mid-season drainage in flooded rice is known to reduce CH4 emission, while effects on N2O emission are more variable. Banning of crop-residue burning, and growing markets for organically fertilized rice, are resulting in systems with larger reactive C input, and potentially larger methane emissions. Tight farming systems with 2 or 3 annual crops are effective in mitigating emissions, in that the land sparing value is high, but put serious constraints on mitigation options under increased C input scenarios. In a series of field (Cambodia, Philippines and Vietnam) and greenhouse experiments, we investigated the effect of a variety of organic amendments and wetting and drying cycles on yield and GHG emissions. Specifically we have tested the effect of inserting very early, or even-pre-planting drainage, as a means to accelerate turnover of straw or other C sources, and reduce methane emission later in the season. Overall, our results showed that drying periods had minimal impact on yields, while reducing overall GHG emission. Methane emission was strongly controlled by C availability in the substrate (on equal total C-input basis), increasing in the order: biochar-composts-animal manure-fresh material. Nitrous oxide emissions generally increased with draining cycles, but did not lead to overall increase in GHG emissions as its contribution was balanced by lowered CH4 emissions. Growth chamber experiments showed that methane emission was significantly reduced for extended periods after re-flooding, hence the idea of early drainage was developed. Meanwhile, Cambodian farmers expressed concerns over re-supply of water after drainage. In response to that, we tested if early-season drainage could replace mid-season drainage. With addition of labile carbon substrates (straw) duration of early season drainage was more important for reducing GHG emissions, than duration of mid-season drainage, and had the highest potential for total emission reduction. In a farmers-field trial in Vietnam, pre-planting and early season drainage was tested in spring and summer rice, under individual and community water management regimes, and at 2 straw application levels. Pre-season drainage was difficult for farmers to implement, due to the short duration of fallow between cropping seasons. Early season drainage was most effective in lowering methane emissions at both straw application levels. Unsurprisingly, the well-managed drainage control (community system) was significantly more effective in mitigating emissions, than the individually water management. Surveys among farming communities in Philippines, subject to agricultural campaigns on alternate-wetting-and-drying showed higher adoption among farmers who actively pumped water to their fields, compared to gravity-fed water supply, due to the direct savings experienced by farmers pumping water. Several other factors positively influenced adoption of mitigation techniques, including education level, access to extension services, wealth and farm size, and age of farmer (negatively correlated to adoption rate). In conclusion, drainage periods are even more important to mitigate emissions when including organic manures or residues in flooded rice, and early-season drainage should be further explored as a more safe and convenient option for smallholders. Participatory development of climate smart prototypes will be essential, and a model for such is presented.

40 CFR 1039.801 - What definitions apply to this part?

Code of Federal Regulations, 2012 CFR

2012-07-01

... operation in water. Auxiliary emission-control device means any element of design that senses temperature... element of design that controls or reduces the emissions of regulated pollutants from an engine. Emission... POLLUTION CONTROLS CONTROL OF EMISSIONS FROM NEW AND IN-USE NONROAD COMPRESSION-IGNITION ENGINES Definitions...

40 CFR 1039.801 - What definitions apply to this part?

Code of Federal Regulations, 2010 CFR

2010-07-01

... operation in water. Auxiliary emission-control device means any element of design that senses temperature... element of design that controls or reduces the emissions of regulated pollutants from an engine. Emission... POLLUTION CONTROLS CONTROL OF EMISSIONS FROM NEW AND IN-USE NONROAD COMPRESSION-IGNITION ENGINES Definitions...

40 CFR 1039.801 - What definitions apply to this part?

Code of Federal Regulations, 2011 CFR

2011-07-01

... operation in water. Auxiliary emission-control device means any element of design that senses temperature... element of design that controls or reduces the emissions of regulated pollutants from an engine. Emission... POLLUTION CONTROLS CONTROL OF EMISSIONS FROM NEW AND IN-USE NONROAD COMPRESSION-IGNITION ENGINES Definitions...

40 CFR 1060.103 - What permeation emission control requirements apply for fuel tanks?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false What permeation emission control... AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EVAPORATIVE EMISSIONS FROM NEW AND IN-USE NONROAD AND STATIONARY EQUIPMENT Emission Standards and Related Requirements § 1060.103 What permeation...

[Effects of biochar application three-years ago on global warming potentials of CH4 and N2O in a rice-wheat rotation system.

PubMed

Wu, Zhen; Dong, Yu Bing; Xiong, Zheng Qin

2018-01-01

To evaluate the long-term effects of biochar amendment on greenhouse gas emissions (GHGs), a field experiment was conducted to examine the effects of 3-year field-aged biochar (B 3 ) and fresh biochar (B 0 ) on global warming potential (GWP) and greenhouse gas intensity (GHGI) of methane (CH 4 ) and nitrous oxide (N 2 O) in a typical rice-wheat rotation system. Four treatments were established as control without nitrogen fertilizer (CK), urea without biochar (N), urea with fresh biochar amended in 2015 (NB 0 ), and urea with 3-year field-aged biochar amended in 2012 (NB 3 ). Results showed that both the NB 0 and NB 3 treatments obviously increased soil pH, soil organic carbon (SOC), total nitrogen (TN) and influenced the potential activity of functional microorganisms related to GHGs compared to the N treatment. Relative to the N treatment, the NB 3 treatment significantly improved crop yield by 14.1% while reduced the CH 4 and N 2 O emissions by 9.0% and 34.0%, respectively. In addition, the NB 0 treatment significantly improved crop yield by 9.3%, while reduced the N 2 O emission by 38.6% though increased the CH 4 emissions by 4.7% relative to the N treatment. Moreover, both the NB 0 and NB 3 treatments could significantly reduce both GWP and GHGI, with NB 3 being more effective in simultaneously mitigating the GHGs emissions and enhancing crop yield. Since field-aged biochar showed obvious effects on GHGs mitigation and carbon sequestration after 3 years, biochar incorporations had long-term effect on GHGs mitigation and crop production in the rice-wheat rotation system.

[Emissions from dairy industry and the influence of herd management].

PubMed

Dämmgen, Ulrich; Brade, Wilfried; Haenel, Hans-Dieter; Rösemann, Claus; Dämmgen, Jürgen; Meyer, Ulrich

2017-08-11

The purpose of this paper is to identify specific emission-reduction opportunities in dairy herds arising from aspects of useful herd management with the potential to reduce emissions, which are within the scope of veterinary activities. In future, it might be one of a veterinarian's advisory capacities to deal with the aspect of climate and environmental protection in animal husbandry. The models involved are similar to those of the national agricultural emission inventory. They allow quantifying the impacts of improved animal health, extended productive lifespan and grazing of an entire dairy herd (cows, calves, heifers and bulls) on emissions from the herd itself, in addition to those originating from the entire production chain, including provision of primary energy, water, feed production and processing. Ammonia emissions are the main focus. The reductions achieved here are not huge, though noticeable. They do not create extra costs. As can be shown, improved animal health and welfare are also environmentally beneficial. The reduction of greenhouse gas and air pollutant (eutrophying and acidifying gases and particles) emissions is an acknowledged political goal. If Germany wants to achieve the emission ceilings it has agreed to, agriculture will have to contribute. Planning will have to precede action if agriculture is itself to keep control of the processes.

Sectoral linkage analysis of three main air pollutants in China's industry: Comparing 2010 with 2002.

PubMed

He, Weiwei; Wang, Yuan; Zuo, Jian; Luo, Yincheng

2017-11-01

To investigate the driving forces of air pollution in China, the changes in linkages amongst inter-industrial air pollutant emissions were analyzed by hypothetical extraction method under the input-output framework. Results showed that the emissions of SO 2 , soot and dust from industrial sources increased by 56.46%, 36.95% and 11.69% respectively in 2010, compared with 2002. As major contributors to emissions, the power and gas sectors were responsible for the growing SO 2 emissions, the nonmetal products sector for soot emissions, and the metals mining, smelting and pressing sectors for dust emissions. The increasing volume of emissions was mainly driven by the growing demand in the transport equipment and electrical equipment sectors. In addition, the expansion in the metals mining, smelting and pressing sectors could result in even more severe air pollution. Therefore, potential effective strategies to control air pollution in China are: (1) reducing the demand of major import sectors in the equipment manufacturing industry; (2) promoting R&D in low-emissions-production technologies to the power and gas sectors, the metals mining, smelting and pressing sectors, and the nonmetal products sector, and (3) auditing the considerable industrial scale expansion in the metals mining, smelting and pressing sectors and optimizing the industrial structure. Copyright © 2017 Elsevier Ltd. All rights reserved.

Numerical Study of Low Emission Gas Turbine Combustor Concepts

NASA Technical Reports Server (NTRS)

Yang, Song-Lin

2002-01-01

To further reduce pollutant emissions, such as CO, NO(x), UHCs, etc., in the next few decades, innovative concepts of gas turbine combustors must be developed. Several concepts, such as the LIPP (Lean- Premixed- Prevaporized), RQL (Rich-Burn Quick-Quench Lean-Burn), and LDI (Lean-Direct-Injection), have been under study for many years. To fully realize the potential of these concepts, several improvements, such as inlet geometry, air swirler, aerothermochemistry control, fuel preparation, fuel injection and injector design, etc., must be made, which can be studied through the experimental method and/or the numerical technique. The purpose of this proposal is to use the CFD technique to study, and hence, to guide the design process for low emission gas turbine combustors. A total of 13 technical papers have been (or will be) published.

Potential for biological nitrification inhibition to reduce nitrification and N2O emissions in pasture crop-livestock systems.

PubMed

Subbarao, G V; Rao, I M; Nakahara, K; Sahrawat, K L; Ando, Y; Kawashima, T

2013-06-01

Agriculture and livestock production systems are two major emitters of greenhouse gases. Methane with a GWP (global warming potential) of 21, and nitrous oxide (N2O) with a GWP of 300, are largely emitted from animal production agriculture, where livestock production is based on pasture and feed grains. The principal biological processes involved in N2O emissions are nitrification and denitrification. Biological nitrification inhibition (BNI) is the natural ability of certain plant species to release nitrification inhibitors from their roots that suppress nitrifier activity, thus reducing soil nitrification and N2O emission. Recent methodological developments (e.g. bioluminescence assay to detect BNIs in plant root systems) have led to significant advances in our ability to quantify and characterize the BNI function. Synthesis and release of BNIs from plants is a highly regulated process triggered by the presence of NH4 + in the rhizosphere, which results in the inhibitor being released precisely where the majority of the soil-nitrifier population resides. Among the tropical pasture grasses, the BNI function is strongest (i.e. BNI capacity) in Brachiaria sp. Some feed-grain crops such as sorghum also have significant BNI capacity present in their root systems. The chemical identity of some of these BNIs has now been established, and their mode of inhibitory action on Nitrosomonas has been characterized. The ability of the BNI function in Brachiaria pastures to suppress N2O emissions and soil nitrification potential has been demonstrated; however, its potential role in controlling N2O emissions in agro-pastoral systems is under investigation. Here we present the current status of our understanding on how the BNI functions in Brachiaria pastures and feed-grain crops such as sorghum can be exploited both genetically and, from a production system's perspective, to develop low-nitrifying and low N2O-emitting production systems that would be economically profitable and ecologically sustainable.

Brownfields and health risks--air dispersion modeling and health risk assessment at landfill redevelopment sites.

PubMed

Ofungwu, Joseph; Eget, Steven

2006-07-01

Redevelopment of landfill sites in the New Jersey-New York metropolitan area for recreational (golf courses), commercial, and even residential purposes seems to be gaining acceptance among municipal planners and developers. Landfill gas generation, which includes methane and potentially toxic nonmethane compounds usually continues long after closure of the landfill exercise phase. It is therefore prudent to evaluate potential health risks associated with exposure to gas emissions before redevelopment of the landfill sites as recreational, commercial, and, especially, residential properties. Unacceptably high health risks would call for risk management measures such as limiting the development to commercial/recreational rather than residential uses, stringent gas control mechanisms, interior air filtration, etc. A methodology is presented for applying existing models to estimate residual landfill hazardous compounds emissions and to quantify associated health risks. Besides the toxic gas constituents of landfill emissions, other risk-related issues concerning buried waste, landfill leachate, and explosive gases were qualitatively evaluated. Five contiguously located landfill sites in New Jersey intended for residential and recreational redevelopment were used to exemplify the approach.

New potentials for conventional aircraft when powered by hydrogen-enriched gasoline

NASA Technical Reports Server (NTRS)

Menard, W. A.; Moynihan, P. I.; Rupe, J. H.

1976-01-01

Hydrogen enrichment for aircraft piston engines is under study in a new NASA program. The objective of the program is to determine the feasibility of inflight injection of hydrogen in general aviation aircraft engines to reduce fuel consumption and to lower emission levels. A catalytic hydrogen generator will be incorporated as part of the air induction system of a Lycoming turbocharged engine and will generate hydrogen by breaking down small amounts of the aviation gasoline used in the normal propulsion system. This hydrogen will then be mixed with gasoline and compressed air from the turbocharger before entering the engine combustion chamber. The special properties of the hydrogen-enriched gasoline allow the engine to operate at ultralean fuel/air ratios, resulting in higher efficiencies and hence less fuel consumption. This paper summarizes the results of a systems analysis study. Calculations assuming a Beech Duke aircraft indicate that fuel savings on the order of 20% are possible. An estimate of the potential for the utilization of hydrogen enrichment to control exhaust emissions indicates that it may be possible to meet the 1979 Federal emission standards.

Buoyancy Effects in Fully-Modulated, Turbulent Diffusion Flames

NASA Technical Reports Server (NTRS)

Hermanson, J. C.; Johari, H.; Ghaem-Maghami, E.; Stocker, D. P.; Hegde, U. G.; Page, K. L.

2003-01-01

Pulsed combustion appears to have the potential to provide for rapid fuel/air mixing, compact and economical combustors, and reduced exhaust emissions. The objective of this experiment (PuFF, for Pulsed-Fully Flames) is to increase the fundamental understanding of the fuel/air mixing and combustion behavior of pulsed, turbulent diffusion flames by conducting experiments in microgravity. In this research the fuel jet is fully-modulated (i.e., completely shut off between pulses) by an externally controlled valve system. This gives rise to drastic modification of the combustion and flow characteristics of flames, leading to enhanced fuel/air mixing compared to acoustically excited or partially-modulated jets. Normal-gravity experiments suggest that the fully-modulated technique also has the potential for producing turbulent jet flames significantly more compact than steady flames with no increase in exhaust emissions. The technique also simplifies the combustion process by avoiding the acoustic forcing generally present in pulsed combustors. Fundamental issues addressed in this experiment include the impact of buoyancy on the structure and flame length, temperatures, radiation, and emissions of fully-modulated flames.

Brain inflammation accompanies amyloid in the majority of mild cognitive impairment cases due to Alzheimer's disease.

PubMed

Parbo, Peter; Ismail, Rola; Hansen, Kim V; Amidi, Ali; Mårup, Frederik H; Gottrup, Hanne; Brændgaard, Hans; Eriksson, Bengt O; Eskildsen, Simon F; Lund, Torben E; Tietze, Anna; Edison, Paul; Pavese, Nicola; Stokholm, Morten G; Borghammer, Per; Hinz, Rainer; Aanerud, Joel; Brooks, David J

2017-07-01

See Kreisl (doi:10.1093/awx151) for a scientific commentary on this article.Subjects with mild cognitive impairment associated with cortical amyloid-β have a greatly increased risk of progressing to Alzheimer's disease. We hypothesized that neuroinflammation occurs early in Alzheimer's disease and would be present in most amyloid-positive mild cognitive impairment cases. 11C-Pittsburgh compound B and 11C-(R)-PK11195 positron emission tomography was used to determine the amyloid load and detect the extent of neuroinflammation (microglial activation) in 42 mild cognitive impairment cases. Twelve age-matched healthy control subjects had 11C-Pittsburgh compound B and 10 healthy control subjects had 11C-(R)-PK11195 positron emission tomography for comparison. Amyloid-positivity was defined as 11C-Pittsburgh compound B target-to-cerebellar ratio above 1.5 within a composite cortical volume of interest. Supervised cluster analysis was used to generate parametric maps of 11C-(R)-PK11195 binding potential. Levels of 11C-(R)-PK11195 binding potential were measured in a selection of cortical volumes of interest and at a voxel level. Twenty-six (62%) of 42 mild cognitive impairment cases showed a raised cortical amyloid load compared to healthy controls. Twenty-two (85%) of the 26 amyloid-positive mild cognitive impairment cases showed clusters of increased cortical microglial activation accompanying the amyloid. There was a positive correlation between levels of amyloid load and 11C-(R)-PK11195 binding potentials at a voxel level within subregions of frontal, parietal and temporal cortices. 11C-(R)-PK11195 positron emission tomography reveals increased inflammation in a majority of amyloid positive mild cognitive impairment cases, its cortical distribution overlapping that of amyloid deposition. © The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The southern Brazilian grassland biome: soil carbon stocks, fluxes of greenhouse gases and some options for mitigation.

PubMed

Pillar, V D; Tornquist, C G; Bayer, C

2012-08-01

The southern Brazilian grassland biome contains highly diverse natural ecosystems that have been used for centuries for grazing livestock and that also provide other important environmental services. Here we outline the main factors controlling ecosystem processes, review and discuss the available data on soil carbon stocks and greenhouse gases emissions from soils, and suggest opportunities for mitigation of climatic change. The research on carbon and greenhouse gases emissions in these ecosystems is recent and the results are still fragmented. The available data indicate that the southern Brazilian natural grassland ecosystems under adequate management contain important stocks of organic carbon in the soil, and therefore their conservation is relevant for the mitigation of climate change. Furthermore, these ecosystems show a great and rapid loss of soil organic carbon when converted to crops based on conventional tillage practices. However, in the already converted areas there is potential to mitigate greenhouse gas emissions by using cropping systems based on no soil tillage and cover-crops, and the effect is mainly related to the potential of these crop systems to accumulate soil organic carbon in the soil at rates that surpass the increased soil nitrous oxide emissions. Further modelling with these results associated with geographic information systems could generate regional estimates of carbon balance.

Characterization of in-use light-duty gasoline vehicle emissions by remote sensing in Beijing: impact of recent control measures.

PubMed

Zhou, Yu; Fu, Lixin; Cheng, Linglin

2007-09-01

China's national government and Beijing city authorities have adopted additional control measures to reduce the negative impact of vehicle emissions on Beijing's air quality. An evaluation of the effectiveness of these measures may provide guidance for future vehicle emission control strategy development. In-use emissions from light-duty gasoline vehicles (LDGVs) were investigated at five sites in Beijing with remote sensing instrumentation. Distance-based mass emission factors were derived with fuel consumption modeled on real world data. The results show that the recently implemented aggressive control strategies are significantly reducing the emissions of on-road vehicles. Older vehicles are contributing substantially to the total fleet emissions. An earlier program to retrofit pre-Euro cars with three-way catalysts produced little emission reduction. The impact of model year and driving conditions on the average mass emission factors indicates that the durability of vehicles emission controls may be inadequate in Beijing.

The Impact of a Potential Shale Gas Development in Germany and the United Kingdom on Pollutant and Greenhouse Gas Emissions

NASA Astrophysics Data System (ADS)

Weger, L.; Cremonese, L.; Bartels, M. P.; Butler, T. M.

2016-12-01

Several European countries with domestic shale gas reserves are considering extracting this natural gas resource to complement their energy transition agenda. Natural gas, which produces lower CO2 emissions upon combustion compared to coal or oil, has the potential to serve as a bridge in the transition from fossil fuels to renewables. However, the generation of shale gas leads to emissions of CH4 and pollutants such as PM, NOx and VOCs, which in turn impact climate as well as local and regional air quality. In this study, we explore the impact of a potential shale gas development in Europe, specifically in Germany and the United Kingdom, on emissions of greenhouse gases and pollutants. In order to investigate the effect on emissions, we first estimate a range of wells drilled per year and production volume for the two countries under examination based on available geological information and on regional infrastructural and economic limitations. Subsequently we assign activity data and emissions factors to the well development, gas production and processing stages of shale gas generation to enable emissions quantification. We then define emissions scenarios to explore different storylines of potential shale gas development, including low emissions (high level of regulation), high emissions (low level of regulation) and middle emissions scenarios, which influence fleet make-up, emission factor and activity data choices for emissions quantification. The aim of this work is to highlight important variables and their ranges, to promote discussion and communication of potential impacts, and to construct possible visions for a future shale gas development in the two study countries. In a follow-up study, the impact of pollutant emissions from these scenarios on air quality will be explored using the Weather Research and Forecasting model with chemistry (WRF-Chem) model.

A comprehensive evaluation of the influence of air combustion and oxy-fuel combustion flue gas constituents on Hg(0) re-emission in WFGD systems.

PubMed

Ochoa-González, Raquel; Díaz-Somoano, Mercedes; Martínez-Tarazona, M Rosa

2014-07-15

This paper evaluates the influence of the main constituents of flue gases from coal combustion (CO2, O2, N2 and water vapor), in air and oxy-fuel combustion conditions on the re-emission of Hg(0) in wet scrubbers. It was observed that the concentration of water vapor does not affect the re-emission of mercury, whereas O2 and CO2 have a notable influence. High concentrations of O2 in the flue gas prevent the re-emission of Hg(0) due to the reaction of oxygen with the metals present in low oxidation states. High concentrations of CO2, which cause a decrease in the pH and the redox potential of gypsum slurries, reduce the amount of Hg(0) that is re-emitted. As a consequence, the high content of CO2 in oxy-fuel combustion may decrease the re-emission of Hg(0) due to the solubility of CO2 in the suspension and the decrease in the pH. It was also found that O2 affects the stabilization of Hg(2+) species in gypsum slurries. The results of this study confirm that the amount of metals present in limestone as well as the redox potential and pH of the slurries in wet desulphurization plants need to be strictly controlled to reduce Hg(0) re-emissions from power plants operating under oxy-fuel combustion conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

Photoluminescence imaging of solitary dopant sites in covalently doped single-wall carbon nanotubes

DOE PAGES

Hartmann, Nicolai F.; Yalcin, Sibel Ebru; Adamska, Lyudmyla; ...

2015-11-11

Covalent dopants in semiconducting single wall carbon nanotubes (SWCNTs) are becoming important as routes for introducing new photoluminescent emitting states with potential for enhanced quantum yields, new functionality, and as species capable of near-IR room-temperature single photon emission. The origin and behavior of the dopant-induced emission is thus important to understand as a key requirement for successful room-T photonics and optoelectronics applications. Here, we use direct correlated two-color photoluminescence imaging to probe how the interplay between the SWCNT bright E 11 exciton and solitary dopant sites yields the dopant-induced emission for three different dopant species: oxygen, 4-methoxybenzene, and 4-bromobenzene. Wemore » introduce a route to control dopant functionalization to a low level as a means for introducing spatially well-separated solitary dopant sites. Resolution of emission from solitary dopant sites and correlation to their impact on E 11 emission allows confirmation of dopants as trapping sites for localization of E 11 excitons following their diffusive transport to the dopant site. Imaging of the dopant emission also reveals photoluminescence intermittency (blinking), with blinking dynamics being dependent on the specific dopant. Density functional theory calculations were performed to evaluate the stability of dopants and delineate the possible mechanisms of blinking. Furthermore, theoretical modeling suggests that the trapping of free charges in the potential well created by permanent dipoles introduced by dopant atoms/groups is likely responsible for the blinking, with the strongest effects being predicted and observed for oxygen-doped SWCNTs.« less

Effect of atmospheric ageing on volatility and ROS of biodiesel exhaust nano-particles

NASA Astrophysics Data System (ADS)

Pourkhesalian, A. M.; Stevanovic, S.; Rahman, M. M.; Faghihi, E. M.; Bottle, S. E.; Masri, A. R.; Brown, R. J.; Ristovski, Z. D.

2015-03-01

In the prospect of limited energy resources and climate change, effects of alternative biofuels on primary emissions are being extensively studied. Our two recent studies have shown that biodiesel fuel composition has a~significant impact on primary particulate matter emissions. It was also shown that particulate matter caused by biodiesels was substantially different from the emissions due to petroleum diesel. Emissions appeared to have higher oxidative potential with the increase in oxygen content and decrease of carbon chain length and unsaturation levels of fuel molecules. Overall, both studies concluded that chemical composition of biodiesel is more important than its physical properties in controlling exhaust particle emissions. This suggests that the atmospheric ageing processes, including secondary organic aerosol formation, of emissions from different fuels will be different as well. In this study, measurements were conducted on a modern common-rail diesel engine. To get more information on realistic properties of tested biodiesel particulate matter once they are released into the atmosphere, particulate matter was exposed to atmospheric oxidants, ozone and ultra-violet light; and the change in their properties was monitored for different biodiesel blends. Upon the exposure to oxidative agents, the chemical composition of the exhaust changes. It triggers the cascade of photochemical reactions resulting in the partitioning of semi-volatile compounds between the gas and particulate phase. In most of the cases, aging lead to the increase in volatility and oxidative potential, and the increment of change was mainly dependent on the chemical composition of fuels as the leading cause for the amount and the type of semi-volatile compounds present in the exhaust.

Relative impact of short-term emissions controls on gas and particle-phase oxidative potential during the 2015 China Victory Day Parade in Beijing, China

NASA Astrophysics Data System (ADS)

Huang, Wei; Fang, Dongqing; Shang, Jing; Li, Zhengqiang; Zhang, Yang; Huo, Peng; Liu, Zhaoying; Schauer, James J.; Zhang, Yuanxun

2018-06-01

A field observation focusing on reactive oxygen species (ROS) was conducted before, during, and after the 2015 China Victory Day Parade to understand the influence of short-term emissions controls on atmospheric oxidative activity. The hourly average concentrations of PM2.5, SO2, NO, NO2, CO, O3, as well as gas and particle-phase ROS, were measured using a series of online instruments. PM2.5 concentrations during control days were significantly lower than non-control days, which directly lead to the "Parade Blue", yet reductions of most gaseous pollutants except SO2 were not so obvious as PM. Similarly, the control measures also led to a great loss of particle-phase ROS throughout the control period, while the reduction of ROS in gas phase was not obvious until the more stringent measures implemented since September 1. Furthermore, only weak positive correlations were observed among ROS and some other measured species, indicating ROS concentrations were affected by a number of comprehensive factors that single marker could not capture. Meanwhile, meteorological condition and regional transportation were also shown to be the minor factors affecting atmospheric oxidizing capacity. The results of this observation mainly revealed the control measures were conducive to reducing particle-related ROS. However, the reduction of gas-phase ROS activity was less effective given the menu of controls employed for the 2015 China Victory Day Parade. Therefore, short-term emissions controls only aimed to PM reduction and visibility improvement will produce the blue sky but will not equivalently reduce the gas-phase ROS. Supplemental control measures will be needed to further reduce gas-phase ROS concentrations.

Potential Impact of the National Plan for Future Electric Power Supply on Air Quality in Korea

NASA Astrophysics Data System (ADS)

Shim, C.; Hong, J.

2014-12-01

Korean Ministry of Trade, Industry and Energy (MOTIE) announced the national plan for Korea's future electric power supply (2013 - 2027) in 2013. According to the plan, the national demand for electricity will be increased by 60% compared to that of 2010 and primary energy sources for electric generation will still lean on the fossil fuels such as petroleum, LNG, and coal, which would be a potential threat to air quality of Korea. This study focused on two subjects: (1) How the spatial distribution of the primary air pollutant's emissions (i.e., NOx, SOx, CO, PM) will be changed and (2) How the primary emission changes will influence on the national ambient air quality including ozone in 2027. We used GEOS-Chem model simulation with modification of Korean emissions inventory (Clean Air Policy Support System (CAPSS)) to simulate the current and future air quality in Korea. The national total emissions of CO, NOx, SOx, PM in year 2027 will be increased by 3%, 8%, 13%, 2%, respectively compared to 2010 and there are additional concern that the future location of the power plants will be closer to the Seoul Metropolitan Area (SMA), where there are approximately 20 million population vulnerable to the potentially worsened air quality. While there are slight increase of concentration of CO, NOx, SOx, and PM in 2027, the O3 concentration is expected to be similar to the level of 2010. Those results may imply the characteristics of air pollution in East Asia such as potentially severe O3 titration and poorer O3/CO or O3/NOx ratio. Furthermore, we will discuss on the impact of transboundary pollution transport from China in the future, which is one of the large factors to control the air quality of Korea.

The rate of aucubin, a secondary metabolite in Plantago lanceolata and potential nitrification inhibitor, needed to reduce ruminant urine patch nitrous oxide emissions

NASA Astrophysics Data System (ADS)

Gardiner, C. A.; Clough, T.; Cameron, K.; Di, H.; Edwards, G. R.

2017-12-01

Nitrous oxide (N2O) losses derived from grazing ruminant livestock urine patches account for 40% of global N2O emissions. It has been shown that Plantago lanceolata, an herb species used in grazed pastures, contains an active secondary metabolite (aucubin) that has the potential to be excreted by grazing ruminants and inhibit nitrification in the urine patch, a key step in soil N2O production. However, the urinary excretion rate of aucubin needed to significantly reduce urine patch N2O emissions remains unknown. Aucubin was dissolved in bovine urine at three rates (47, 243, and 486 kg ha-1), based on rates used in Dietz et al. (2013) and the calculated highest potential aucubin application rate, from Gardiner et al. (2017). A control, along with a urine treatment and the three aucubin treatments (all urine applied at 700 kg N ha-1), was applied to 20 g soil and incubated in the laboratory for 35 d. Soils were monitored for surface pH, inorganic N concentration (NH4+/NO3-), and gas (N2O and CO2) fluxes. This experiment is currently underway and the results will be presented at the conference. Dietz M, Machill S, Hoffmann H, Schmidtke K 2013. Inhibitory effects of Plantago lanceolata L. on soil N mineralization. Plant and Soil 368: 445-458. Gardiner CA, Clough TJ, Cameron KC, Di HJ, Edwards GR, de Klein CAM 2017. The potential inhibitory effects of Plantago lanceolata and its active secondary metabolite aucubin on soil nitrification and nitrous oxide emissions under ruminant urine patch conditions. Manuscript submitted for publication.

A Review on Mitigation Technologies for Controlling Urban Heat Island Effect in Housing and Settlement Areas

NASA Astrophysics Data System (ADS)

Andoni, Heri; Wonorahardjo, Surjamanto

2018-05-01

Urban Heat Island (UHI) has many harm impacts to urban and human life, the examples are increased building and energy consumption, increased air pollutants emissions, compromised human comfort and health, and many more. Despite UHI phenomenon and those impacts has been realized long enough by the experts along with development of major cities in the world, but its mitigation technology has not been well developed. This paper discusses few mitigation technologies for UHI phenomenon that have been developed by experts. Some mitigation technologies such as double skin façade, shading strategies, and many more are discussed in this study, include the strengths and the weaknesses of each strategy. The focus of the study is mainly on the potential of building skin engineering in which thermal conductivity, infrared emissivity, and specific heat factors. The selected case discussed are buildings made of heavy weight materials. The result in this study reveals a potential map where thermal insulation is one potential strategy to reduce the intensity of UHI through the reduction of heat emissions of heavy building materials components. By this study, improvement of the urban life in its relation to UHI are expected to occur, especially in housing and settlements area.

An overview of monitoring and reduction strategies for health and climate change related emissions in the Middle East and North Africa region

NASA Astrophysics Data System (ADS)

Abbass, Rana Alaa; Kumar, Prashant; El-Gendy, Ahmed

2018-02-01

This review assesses the current state of air pollution in the Middle East and North Africa (MENA) region. Emission types and sources in the region are identified and quantified to understand the monitoring, legislative and reduction needs through a systematic review of available literature. It is found that both health (e.g., particulate matter, PM; and heavy metals) and climate change (e.g., carbon dioxide and methane) emissions are increasing with the time. Regarding health emissions, over 99% of the MENA population is exposed to PM levels that exceed the standards set by the World Health Organization (WHO). The dominant source of climate change emissions is the energy sector contributing ∼38% of CO2 emissions, followed by the transport sector at ∼25%. Numerous studies have been carried out on air pollution in the region, however, there is a lack of comprehensive regional studies that would provide a holistic assessment. Most countries have air quality monitoring systems in place, however, the data is not effectively evaluated to devise pollution reduction strategies. Moreover, comprehensive emission inventories for the individual countries in the region are also lacking. The legislative and regulatory systems in MENA region follow the standards set by international environmental entities such as the WHO and the U.S. Environmental Protection Agency but their effective reinforcement remains a concern. It is concluded that the opportunities for emission reduction and control could be best implemented in the road transportation sector using innovative technologies. One of the potential ways forward is to channel finance flows from fossil fuel subsidies to upgrade road transport with public transportation systems such as buses and trains, as suggested by a 'high shift' scenario for MENA region. Furthermore, emission control programs and technologies are more effective when sponsored and implemented by the private sector; the success of Saudi Aramco in supporting national emission monitoring is one such example. Finally, an energy-pollution-water nexus is assessed for the region as an integrated approach to address its urban issues. The assessment of topic areas covered clearly suggests a need to control the main sources of air pollution to limit its relatively high impact on the human health in the MENA region.

[Impact of Phosphogypsum Wastes on the Wheat Growth and CO2 Emissions and Evaluation of Economic-environmental Benefit].

PubMed

Li, Ji; Wu, Hong-sheng; Gao, Zhi-qiu; Shang, Xiao-xia; Zheng, Pei-hui; Yin, Jin; Kakpa, Didier; Ren, Qian-qi; Faustin, Ogou Katchele; Chen, Su-yun; Xu, Ya; Yao, Tong-yan; Ji, Wei; Qian, Jing-shan; Ma, Shi-jie

2015-08-01

Phosphogypsum is a phosphorus chemical waste which has not been managed and reused well, resultantly, causing environmental pollution and land-occupation. Phosphogypsum wastes were used as a soil amendment to assess the effect on wheat growth, yield and CO2 emissions from winter wheat fields. Its economic and environmental benefits were analyzed at the same time. The results showed that wheat yield was increased by 37.71% in the treatment of phosphogypsum of 2 100 kg x hm(-2). Compared with the control treatment, throughout the wheat growing season, CO2 emission was accumulatively reduced by 3% in the treatment of phosphogypsum waste of 1050 kg x hm(-2), while reduced by 8% , 10% , and 6% during the jointing stage, heading date and filling period of wheat, respectively; while CO2 emission was accumulatively reduced by 7% in the treatment of phosphogypsum waste of 2 100 kg x hm(-2) throughout the wheat growing season, as reduced by 11% , 4% , and 12% during the reviving wintering stage, heading date and filling period of wheat, respectively. It was better for CO2 emission reduction in the treatment of a larger amount of phosphogypsum waste. In the case of application of phosphogypsum waste residue within a certain range, the emission intensity of CO2 ( CO2 emissions of per unit of fresh weight or CO2 emissions of per unit of yield) , spike length, fresh weight and yield showed a significantly negative correlation--the longer the ear length, the greater fresh weight and yield and the lower the CO2 emissions intensity. As to the carbon trading, phosphogypsum utilization was of high economic and environmental benefits. Compared with the control, the ratio of input to output changed from 1: 8.3 to 1: 10.7, which in the same situation of investment the output could be increased by 28.92% ; phosphogypsum as a greenhouse gas reducing agent in the wheat field, it could decrease the cost and increase the environmental benefit totally about 290 yuan per unit of ton. The results demonstrated phosphogypsum wastes could obviously decrease the CO2 emission from field soil and had a great potential to control agricultural greenhouse gases. Hopefully it has an important application perspective for the low-carbon, ecological and sustainable agricultural development.

The Effect of Chemical Amendments Used for Phosphorus Abatement on Greenhouse Gas and Ammonia Emissions from Dairy Cattle Slurry: Synergies and Pollution Swapping.

PubMed

Brennan, Raymond B; Healy, Mark G; Fenton, Owen; Lanigan, Gary J

2015-01-01

Land application of cattle slurry can result in incidental and chronic phosphorus (P) loss to waterbodies, leading to eutrophication. Chemical amendment of slurry has been proposed as a management practice, allowing slurry nutrients to remain available to plants whilst mitigating P losses in runoff. The effectiveness of amendments is well understood but their impacts on other loss pathways (so-called 'pollution swapping' potential) and therefore the feasibility of using such amendments has not been examined to date. The aim of this laboratory scale study was to determine how the chemical amendment of slurry affects losses of NH3, CH4, N2O, and CO2. Alum, FeCl2, Polyaluminium chloride (PAC)- and biochar reduced NH3 emissions by 92, 54, 65 and 77% compared to the slurry control, while lime increased emissions by 114%. Cumulative N2O emissions of cattle slurry increased when amended with alum and FeCl2 by 202% and 154% compared to the slurry only treatment. Lime, PAC and biochar resulted in a reduction of 44, 29 and 63% in cumulative N2O loss compared to the slurry only treatment. Addition of amendments to slurry did not significantly affect soil CO2 release during the study while CH4 emissions followed a similar trend for all of the amended slurries applied, with an initial increase in losses followed by a rapid decrease for the duration of the study. All of the amendments examined reduced the initial peak in CH4 emissions compared to the slurry only treatment. There was no significant effect of slurry amendments on global warming potential (GWP) caused by slurry land application, with the exception of biochar. After considering pollution swapping in conjunction with amendment effectiveness, the amendments recommended for further field study are PAC, alum and lime. This study has also shown that biochar has potential to reduce GHG losses arising from slurry application.

The Effect of Chemical Amendments Used for Phosphorus Abatement on Greenhouse Gas and Ammonia Emissions from Dairy Cattle Slurry: Synergies and Pollution Swapping

PubMed Central

Brennan, Raymond B.; Healy, Mark G.; Fenton, Owen; Lanigan, Gary J.

2015-01-01

Land application of cattle slurry can result in incidental and chronic phosphorus (P) loss to waterbodies, leading to eutrophication. Chemical amendment of slurry has been proposed as a management practice, allowing slurry nutrients to remain available to plants whilst mitigating P losses in runoff. The effectiveness of amendments is well understood but their impacts on other loss pathways (so-called ‘pollution swapping’ potential) and therefore the feasibility of using such amendments has not been examined to date. The aim of this laboratory scale study was to determine how the chemical amendment of slurry affects losses of NH3, CH4, N2O, and CO2. Alum, FeCl2, Polyaluminium chloride (PAC)- and biochar reduced NH3 emissions by 92, 54, 65 and 77% compared to the slurry control, while lime increased emissions by 114%. Cumulative N2O emissions of cattle slurry increased when amended with alum and FeCl2 by 202% and 154% compared to the slurry only treatment. Lime, PAC and biochar resulted in a reduction of 44, 29 and 63% in cumulative N2O loss compared to the slurry only treatment. Addition of amendments to slurry did not significantly affect soil CO2 release during the study while CH4 emissions followed a similar trend for all of the amended slurries applied, with an initial increase in losses followed by a rapid decrease for the duration of the study. All of the amendments examined reduced the initial peak in CH4 emissions compared to the slurry only treatment. There was no significant effect of slurry amendments on global warming potential (GWP) caused by slurry land application, with the exception of biochar. After considering pollution swapping in conjunction with amendment effectiveness, the amendments recommended for further field study are PAC, alum and lime. This study has also shown that biochar has potential to reduce GHG losses arising from slurry application. PMID:26053923

The Effect of Dietary Replacement of Ordinary Rice with Red Yeast Rice on Nutrient Utilization, Enteric Methane Emission and Rumen Archaeal Diversity in Goats.

PubMed

Wang, L Z; Zhou, M L; Wang, J W; Wu, D; Yan, T

2016-01-01

Twenty castrated Boer crossbred goats were used in the present study with two treatments to examine the effect of dietary replacement of ordinary rice with red yeast rice on nutrient utilization, enteric methane emission and ruminal archaea structure and composition. Two treatment diets contained (DM basis) 70.0% of forage, 21.8% of concentrates and 8.2% of either ordinary rice (control) or red yeast rice (RYR). Nutrient utilization was measured and enteric methane emissions were determined in respiration chambers. Results showed that RYR had significantly lower digestibility of N and organic matter compared to control group. However, feeding red yeast rice did not affect N retention as g/d or a proportion of N intake, and reduced heat production as MJ/d or as a proportion of metabolizable energy intake, thus leading to a higher proportion of metabolizable energy intake to be retained in body tissue. RYR also had significantly lower methane emissions either as g/d, or as a proportion of feed intake. Although feeding red yeast rice had no negative effect on any rumen fermentation variables, it decreased serum contents of total cholesterol, triglycerides, HDL-cholesterol and LDL-cholesterol. In the present study, 75616 archaeal sequences were generated and clustered into 2364 Operational Taxonomic Units. At the genus level, the predominant archaea in the rumen of goats was Methanobrevibacter, which was significantly inhibited with the supplementation of red yeast rice. In conclusion, red yeast rice is a potential feed ingredient for mitigation of enteric methane emissions of goats. However, caution should be taken when it is used because it may inhibit the digestibility of some nutrients. Further studies are required to evaluate its potential with different diets and animal species, as well as its effects on animal health and food safety.

The blue skies in Beijing during APEC 2014: A quantitative assessment of emission control efficiency and meteorological influence

NASA Astrophysics Data System (ADS)

Liu, Hongli; He, Jing; Guo, Jianping; Miao, Yucong; Yin, Jinfang; Wang, Yuan; Xu, Hui; Liu, Huan; Yan, Yan; Li, Yuan; Zhai, Panmao

2017-10-01

Most previous studies attributed the alleviation of aerosol pollution to either emission control measures or favorable meteorological conditions. However, our understanding of their quantitative contribution is far from complete. In this study, based on model simulation using the CMA (China Meteorological Administration) Unified Atmospheric Chemistry Environment for aerosols (CUACE/Aero), in combination with simultaneous ground-based hourly PM2.5 observations, we aim to quantify the relative contributions of the emission control measures and meteorology to the blue-skies seen in Beijing during the Asia-Pacific Economic Cooperation (APEC) summit held in November of 2014. A series of model simulations have been performed over Beijing-Tianjin-Hebei (BTH) region by implementing nine different emission control schemes. To investigate the relative contributions of the emission control measures and meteorology, the study period has been divided into five episodes. Overall, the CUACE/Aero model can reasonably well reproduce the temporal and spatial evolution of PM2.5 during APEC 2014, although the model performance varies by different time periods and regions of interest. Model results show the emission control measures on average reduced the PM2.5 concentration by 41.3% in urban areas of Beijing and 39.7% in Huairou district, respectively, indicating emission control plays a significant role for the blue skies observed. Among all the emission control measures under investigation, local emission control in Beijing contributed the largest to the reduction of PM2.5 concentrations with a reduction of 35.5% in urban area of Beijing and 34.8% in Huairou, in contrast with the vehicle emission control in Hebei that contributed the least with a reduction of less than 1%. The emission control efficiency in five episodes has been assessed quantitatively, which falls in the range of 36.2%-41.2% in urban area of Beijing and 34.9%-40.7% in Huairou, indicative of no significant episode and geographic dependence in the emission control efficiency. The emission control measures and meteorology, however, alternated to dominate the absolute reduction of PM2.5 concentrations. When the weather conditions are unfavorable, emission control measures outperformed meteorology with a reduction of 55.3-59.4 μg/m3 in urban area of Beijing and 32.5-33 μg/m3 in Huairou. Conversely, when the northwesterly winds prevailed, meteorology tends to outweigh the role of emission control in accounting for the drop of PM2.5. The atmospheric dilution conditions are determined through the model calculation of the mass inflow of PM2.5 per unit volume near the surface. Our findings have significant implications for effective planning and implementation of emission control measures.

Denitrification nitrogen gas formation and gene expression in alpine grassland soil as affected by climate change conditions

NASA Astrophysics Data System (ADS)

Chen, Zhe; Wang, Changhui; Gschwendtner, Silvia; Schloter, Michael; Butterbach-Bahl, Klaus; Dannenmann, Michael

2013-04-01

Due to methodological problems, reliable data on soil dinitrogen (N2) emission by denitrification are extremely scarce, and the impacts of climate change on nitrogen (N) gas formation by denitrification and N gas product ratios as well as the underlying microbial drivers remain unclear. We combined the helium-gas-flow-soil-core technique for simultaneously quantification of nitrous oxide (N2O) and N2 emission with the reverse transcript qPCR technology. Our goals were to characterize denitrification dynamics and N gas product ratios in alpine grassland soil as affected by climate change conditions and to evaluate relationships between denitrification gene expression and N gas emission. We used soils from the pre-alpine grassland Terrestrial Environmental Observatory (TERENO), exposed to ambient temperature and precipitation (control treatment), or three years of simulated climate change conditions (increased temperature, reduction of summer precipitation and reduced snow cover). Soils were amended with glucose and nitrate and incubated subsequently at 1) 5°C and 20% oxygen; 2) 5°C and 0% oxygen; 3) 20°C and 0% oxygen until stabilization of N gas emissions in each incubation step. After switching incubation conditions to 0% oxygen and 20°C, N2O emission peaked immediately and declined again, followed by a delayed peak in N2 emission. The dynamics of cnorB gene expression, encoding the reduction of nitric oxide (NO) to N2O, followed the N2O emission pattern, while nosZ gene expression, encoding N2O reduction to N2 followed the course of N2 emission. The mean N2O:N2 ratios were 1.31 + 0.10 and 1.56 + 0.16 for control and climate change treatment respectively, but the denitrification potential was overall lower in climate change treatment. Hence, simulated climate change promoted N2O but lessened N2 emission. This stimulation of N2O was in accordance with increased cnorB gene expression in soil of the climate change treatment. N mass balance calculations revealed that denitrification N gas formation accounted for 21%, dissimilatory nitrate reduction to ammonium for 8%, and microbial immobilization for 73% of nitrate consumption. Overall, our study shows that changes in climate exert feedback on denitrification N gas formation and N gas product ratios via changes in microbial activity at the level of single denitrification steps. The close relationships found between denitrification N gas formation, N gas product ratios and denitrification gene expression suggests a large potential of molecular methods to predict denitrification dynamics in soil.

Gas phase emissions from cooking processes and their secondary aerosol production potential

NASA Astrophysics Data System (ADS)

Klein, Felix; Platt, Stephen; Bruns, Emily; Termime-roussel, Brice; Detournay, Anais; Mohr, Claudia; Crippa, Monica; Slowik, Jay; Marchand, Nicolas; Baltensperger, Urs; Prevot, Andre; El Haddad, Imad

2014-05-01

Long before the industrial evolution and the era of fossil fuels, high concentrations of aerosol particles were alluded to in heavily populated areas, including ancient Rome and medieval London. Recent radiocarbon measurements (14C) conducted in modern megacities came as a surprise: carbonaceous aerosol (mainly organic aerosol, OA), a predominant fraction of particulate matter (PM), remains overwhelmingly non-fossil despite extensive fossil fuel combustion. Such particles are directly emitted (primary OA, POA) or formed in-situ in the atmosphere (secondary OA, SOA) via photochemical reactions of volatile organic compounds (VOCs). Urban levels of non-fossil OA greatly exceed the levels measured in pristine environments strongly impacted by biogenic emissions, suggesting a contribution from unidentified anthropogenic non-fossil sources to urban OA. Positive matrix factorization (PMF) techniques applied to ambient aerosol mass spectrometer (AMS, Aerodyne) data identify primary cooking emissions (COA) as one of the main sources of primary non-fossil OA in major cities like London (Allan et al., 2010), New York (Sun et al., 2011) and Beijing (Huang et al., 2010). Cooking processes can also emit VOCs that can act as SOA precursors, potentially explaining in part the high levels of oxygenated OA (OOA) identified by the AMS in urban areas. However, at present, the chemical nature of these VOCs and their secondary aerosol production potential (SAPP) remain virtually unknown. The approach adopted here involves laboratory quantification of PM and VOC emission factors from the main primary COA emitting processes and their SAPP. Primary emissions from deep-fat frying, vegetable boiling, vegetable frying and meat cooking for different oils, meats and vegetables were analysed under controlled conditions after ~100 times dilution. A high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and a high resolution proton transfer time-of-flight mass spectrometer (PTR-ToF-MS) were used to quantify OA and VOC emissions, respectively. SOA production potential of the different emissions was quantified by introducing them into the PSI mobile smog chamber and a potential aerosol chamber (PAM) where they were photochemically aged. The measurements of primary emissions suggest that the COA factor identified in ambient atmospheric aerosols is mostly related to fat release from frying with vegetable oils or grilling fatty-meats. In contrast, vegetable cooking (boiling and frying) was associated with significant VOC emissions. The VOC emissions from frying consist mainly of aldehydes which are formed through breaking of fatty acids. Gas phase composition, emission factors and SAPP from all these processes will be presented. This work was supported by the Swiss National Science Foundation as well as the Swiss Federal Office for the Environment. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n.° 290605 (COFUND: PSI-FELLOW). J. Allan et al, Atmos. Chem. Phys. 10, 647-668 (2010) X.-F. Huang et al, Atmos. Chem. Phys. 10, 8933-8945 (2010) Y.-L. Sun et al, Atmos. Chem. Phys. 11, 1581-1602 (2011)

Impact of pollution controls in Beijing on atmospheric oxygenated volatile organic compounds (OVOCs) during the 2008 Olympic Games: observation and modeling implications

NASA Astrophysics Data System (ADS)

Liu, Y.; Yuan, B.; Li, X.; Shao, M.; Lu, S.; Li, Y.; Chang, C.-C.; Zhu, T.

2014-10-01

Oxygenated volatile organic compounds (OVOCs) are important products of the photo-oxidation of hydrocarbons. They influence the oxidizing capacity and the ozone forming potential of the atmosphere. In the summer of 2008 two months' emission restrictions were enforced in Beijing to improve air quality during the Olympic Games. Observation evidence has been reported in related studies that these control measures were efficient in reducing the concentrations of primary anthropogenic pollutants (CO, NOx and non-methane hydrocarbons, i.e. NMHCs) by 30-40%. In this study, the influence of the emission restrictions on ambient levels of OVOCs was explored using a neural network analysis with consideration of meteorological conditions. Statistically significant reductions in formaldehyde (HCHO), acetaldehyde (CH3CHO), methyl ethyl ketone (MEK) and methanol were found to be 12.9, 15.8, 17.1 and 19.6%, respectively, when the restrictions were in place. The effect of emission control on acetone was not detected in neural network simulations, probably due to pollution transport from surrounding areas outside Beijing. Although the ambient levels of most NMHCs were decreased by ~35% during the full control period, the emission ratios of reactive hydrocarbons attributed to vehicular emissions did not present obvious difference. A zero-dimensional box model based on Master Chemical Mechanism version 3.2 (MCM3.2) was applied to evaluate how OVOCs productions respond to the reduced precursors during the emission controlled period. On average, secondary HCHO was produced from the oxidation of anthropogenic alkenes (54%), isoprene (30%) and aromatics (15%). The importance of biogenic source for the total HCHO formation was almost on a par with that of anthropogenic alkenes during the daytime. Anthropogenic alkenes and alkanes dominated the photochemical production of other OVOCs such as acetaldehyde, acetone and MEK. The relative changes of modelled aldehydes, methyl vinyl ketone and methacrolein (MVK + MACR) before and during the pollution controlled period were comparable to the estimated reductions in the neural network, reflecting that current mechanisms can largely explain secondary production of those species under urban conditions. However, it is worthy to notice that the box model overestimated the measured concentrations of aldehydes by a factor of 1.4-1.7, and simulated MEK was in good agreement with the measurements when primary sources were taken into consideration. These results suggest that the understanding of OVOCs budget in the box model remains incomplete, there is still considerable uncertainty in particular missing sinks (unknown chemical reactions and physical dilution processes) for aldehydes and absence of direct emissions for ketones.

Results from conceptual design study of potential early commercial MHD/steam power plants

NASA Technical Reports Server (NTRS)

Hals, F.; Kessler, R.; Swallom, D.; Westra, L.; Zar, J.; Morgan, W.; Bozzuto, C.

1981-01-01

This paper presents conceptual design information for a potential early MHD power plant developed in the second phase of a joint study of such plants. Conceptual designs of plant components and equipment with performance, operational characteristics and costs are reported on. Plant economics and overall performance including full and part load operation are reviewed. Environmental aspects and the methods incorporated in plant design for emission control of sulfur and nitrogen oxides are reviewed. Results from reliability/availability analysis conducted are also included.

40 CFR 270.27 - Specific Part B information requirements for air emission controls for tanks, surface...

Code of Federal Regulations, 2010 CFR

2010-07-01

... requirements for air emission controls for tanks, surface impoundments, and containers. 270.27 Section 270.27... information requirements for air emission controls for tanks, surface impoundments, and containers. (a) Except... containers that use air emission controls in accordance with the requirements of 40 CFR part 264, subpart CC...

40 CFR 270.27 - Specific Part B information requirements for air emission controls for tanks, surface...

Code of Federal Regulations, 2013 CFR

2013-07-01

... requirements for air emission controls for tanks, surface impoundments, and containers. 270.27 Section 270.27... information requirements for air emission controls for tanks, surface impoundments, and containers. (a) Except... containers that use air emission controls in accordance with the requirements of 40 CFR part 264, subpart CC...

40 CFR 270.27 - Specific Part B information requirements for air emission controls for tanks, surface...

Code of Federal Regulations, 2011 CFR

2011-07-01

... requirements for air emission controls for tanks, surface impoundments, and containers. 270.27 Section 270.27... information requirements for air emission controls for tanks, surface impoundments, and containers. (a) Except... containers that use air emission controls in accordance with the requirements of 40 CFR part 264, subpart CC...

40 CFR 270.27 - Specific Part B information requirements for air emission controls for tanks, surface...

Code of Federal Regulations, 2012 CFR

2012-07-01

... requirements for air emission controls for tanks, surface impoundments, and containers. 270.27 Section 270.27... information requirements for air emission controls for tanks, surface impoundments, and containers. (a) Except... containers that use air emission controls in accordance with the requirements of 40 CFR part 264, subpart CC...

40 CFR 270.27 - Specific Part B information requirements for air emission controls for tanks, surface...

Code of Federal Regulations, 2014 CFR

2014-07-01

... requirements for air emission controls for tanks, surface impoundments, and containers. 270.27 Section 270.27... information requirements for air emission controls for tanks, surface impoundments, and containers. (a) Except... containers that use air emission controls in accordance with the requirements of 40 CFR part 264, subpart CC...

Effects of dicyandiamide and acetylene on N2O emissions and ammonia oxidizers in a fluvo-aquic soil applied with urea.

PubMed

Wang, Qing; Zhang, Li-Mei; Shen, Ju-Pei; Du, Shuai; Han, Li-Li; He, Ji-Zheng

2016-11-01

Ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) are crucial for N 2 O emission as they carry out the key step of nitrification. Dicyandiamide (DCD) and acetylene (C 2 H 2 ) are typical nitrification inhibitors (NIs), while the comparative effects of these NIs on N 2 O production and ammonia oxidizers' (AOB and AOA) growth are unclear. Four treatments including a control, urea, urea + DCD, and urea + C 2 H 2 were set up to investigate their effect of inhibiting soil nitrification, nitrification-related N 2 O emission as well as the growth of ammonia oxidizers with a fluvo-aquic soil using microcosms for 28 days. N 2 O emission and net nitrification rate increased after the application of urea, but were significantly restrained in urea + NI treatments, while C 2 H 2 was more effective in reducing N 2 O emission and nitrification rate than DCD. The abundance of AOB, which was significantly correlated with N 2 O emission and net nitrification rate, was more inhibited by C 2 H 2 than DCD. Furthermore, the application of urea in all the soils had little impact on the AOA community, while obvious shifts of AOB community structure were found compared with the control. All AOB sequences fell within Nitrosospira cluster 3, and the AOA community was clustered to group 1.1b. Collectively, it indicated that application of urea combined with NIs (DCD or C 2 H 2 ) could potentially alter N 2 O emission, mainly through regulating the growth of AOB but not AOA in this fluvo-aquic soil.

Impacts of the Minamata Convention for Mercury Emissions from Coal-fired Power Generation in Asia

NASA Astrophysics Data System (ADS)

Giang, A.; Stokes, L. C.; Streets, D. G.; Corbitt, E. S.; Selin, N. E.

2014-12-01

We explore the potential implications of the recently signed United Nations Minamata Convention on Mercury for emissions from coal-fired power generation in Asia, and the impacts of these emissions changes on deposition of mercury worldwide by 2050. We use qualitative interviews, document analysis, and engineering analysis to create plausible technology scenarios consistent with the Convention, taking into account both technological and political factors. We translate these scenarios into possible emissions inventories for 2050, based on IPCC development scenarios, and then use the GEOS-Chem global transport model to evaluate the effect of these different technology choices on mercury deposition over geographic regions and oceans. We find that China is most likely to address mercury control through co-benefits from technologies for SO2, NOx, and particulate matter (PM) capture that will be required to attain its existing air quality goals. In contrast, India is likely to focus on improvements to plant efficiency such as upgrading boilers, and coal washing. Compared to current technologies, we project that these changes will result in emissions decreases of approximately 140 and 190 Mg/yr for China and India respectively in 2050, under an A1B development scenario. With these emissions reductions, simulated average gross deposition over India and China are reduced by approximately 10 and 3 μg/m2/yr respectively, and the global average concentration of total gaseous mercury (TGM) is reduced by approximately 10% in the Northern hemisphere. Stricter, but technologically feasible, requirements for mercury control in both countries could lead to an additional 200 Mg/yr of emissions reductions. Modeled differences in concentration and deposition patterns between technology suites are due to differences in both the mercury removal efficiency of technologies and their resulting stack speciation.

Optimizing power cylinder lubrication on a large bore natural gas engine

NASA Astrophysics Data System (ADS)

Luedeman, Matthew R.

More than 6000 integral compressors, located along America's natural gas pipelines, pump natural gas across the United States. These compressors are powered by 2-stroke, large bore natural gas burning engines. Lowering the operating costs, reducing the emissions, and ensuring that these engines remain compliant with future emission regulations are the drivers for this study. Substantial research has focused on optimizing efficiency and reducing the fuel derived emissions on this class of engine. However, significantly less research has focused on the effect and reduction of lubricating oil derived emissions. This study evaluates the impact of power cylinder lubricating oil on overall engine emissions with an emphasis on reducing oxidation catalyst poisoning. A traditional power cylinder lubricator was analyzed; power cylinder lubricating oil was found to significantly impact exhaust emissions. Lubricating oil was identified as the primary contributor of particulate matter production in a large bore natural gas engine. The particulate matter was determined to be primarily organic carbon, and most likely direct oil carryover of small oil droplets. The particulate matter production equated to 25% of the injected oil at a nominal power cylinder lubrication rate. In addition, power cylinder friction is considered the primary contributor to friction loss in the internal combustion engine. This study investigates the potential for optimizing power cylinder lubrication by controlling power cylinder injection to occur at the optimal time in the piston cycle. By injecting oil directly into the ring pack, it is believed that emissions, catalyst poisoning, friction, and wear can all be reduced. This report outlines the design and theory of two electronically controlled lubrication systems. Experimental results and evaluation of one of the systems is included.

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. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Effects of Particle Filters and Selective Catalytic Reduction on In-Use Heavy-Duty Diesel Truck Emissions

NASA Astrophysics Data System (ADS)

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

2016-12-01

Heavy-duty diesel trucks (HDDT) are a major source of nitrogen oxides (NOx) and black carbon (BC) in urban environments, contributing to persistent ozone and particulate matter air quality problems. Diesel particle filters (DPFs) and selective catalytic reduction (SCR) systems that target PM and NOx emissions, respectively, have recently become standard equipment on new HDDT. DPFs can also be installed on older engines as a retrofit device. Previous work has shown that DPF and SCR systems can reduce NOx and BC emissions by up to 70% and 90%, respectively, compared to modern trucks without these after-treatment controls (Preble et al., ES&T 2015). DPFs can have the undesirable side-effect of increasing ultrafine particle (UFP) and nitrogen dioxide (NO2) emissions. While SCR systems can partially mitigate DPF-related NO2 increases, these systems can emit nitrous oxide (N2O), a potent greenhouse gas. We report new results from a study of HDDT emissions conducted in fall 2015 at the Port of Oakland and Caldecott Tunnel in California's San Francisco Bay Area. We report pollutant emission factors (g kg-1) for emitted NOx, NO2, BC, PM2.5, UFP, and N2O on a truck-by-truck basis. Using a roadside license plate recognition system, we categorize each truck by its engine model year and installed after-treatment controls. From this, we develop emissions profiles for trucks with and without DPF and SCR. We evaluate the effectiveness of these devices as a function of their age to determine whether degradation is an issue. We also compare the emission profiles of trucks traveling at low speeds along a level, arterial road en route to the port and at high speeds up a 4% grade highway approaching the tunnel. Given the climate impacts of BC and N2O, we also examine the global warming potential of emissions from trucks with and without DPF and SCR.

CO2 emissions driven by wind are produced at global scale

NASA Astrophysics Data System (ADS)

Rosario Moya, M.; Sánchez-Cañete, Enrique P.; Kowalski, Andrew S.; Serrano-Ortiz, Penélope; López-Ballesteros, Ana; Oyonarte, Cecilio; Domingo, Francisco

2017-04-01

As an important tool for understanding and monitoring ecosystem dynamics at ecosystem level, the eddy covariance (EC) technique allows the assessment of the diurnal and seasonal variation of the net ecosystem exchange (NEE). Despite the high temporal resolution data, there are still many processes (in addition to photosynthesis and respiration) that, although they are being monitored, have been neglected. Only a few authors have studied anomalous CO2 emissions (non biological), and have related them to soil ventilation, photodegradation or geochemical processes. The aims of this study are: 1) to identify anomalous daytime CO2 emissions in different ecosystems distributed around the world, 2) to determine the meteorological variables that influence these emissions, and 3) to explore the potential processes which can be involved. We have studied EC data together with other meteorological ancillary variables obtained from the FLUXNET database and have found more than 50 sites with anomalous CO2 emissions in different ecosystem types such as grasslands, croplands or savannas. Data were filtered according to the FLUXNET quality control flags (only data with maximum quality were used, i.e. control flag equal to 0) and daytime (shortwave radiation incoming > 50 W m-2). Partial Spearman correlation analyses were performed between NEE and ancillary data: air temperature, vapour pressure deficit, soil temperature, precipitation, atmospheric pressure, soil water content, incoming photosynthetic photon flux density, friction velocity and net radiation. When necessary, ancillary variables were gap-filled using the MDS method (Reichstein et al. 2005). Preliminary results showed strong and highly significant correlations between friction velocity and anomalous CO2 emissions, suggesting that these emissions were mainly produced by ventilation events. Anomalous CO2 emissions were found mainly in arid ecosystems and sites with hot and dry summers. We suggest that anomalous CO2 emissions occur globally and therefore, their contribution to the global NEE requires further investigation in order to better understand its drivers.

Harnessing Insect-Microbe Chemical Communications To Control Insect Pests of Agricultural Systems.

PubMed

Beck, John J; Vannette, Rachel L

2017-01-11

Insect pests cause serious economic, yield, and food safety problems to managed crops worldwide. Compounding these problems, insect pests often vector pathogenic or toxigenic microbes to plants. Previous work has considered plant-insect and plant-microbe interactions separately. Although insects are well-understood to use plant volatiles to locate hosts, microorganisms can produce distinct and abundant volatile compounds that in some cases strongly attract insects. In this paper, we focus on the microbial contribution to plant volatile blends, highlighting the compounds emitted and the potential for variation in microbial emission. We suggest that these aspects of microbial volatile emission may make these compounds ideal for use in agricultural applications, as they may be more specific or enhance methods currently used in insect control or monitoring. Our survey of microbial volatiles in insect-plant interactions suggests that these emissions not only signal host suitability but may indicate a distinctive time frame for optimal conditions for both insect and microbe. Exploitation of these host-specific microbe semiochemicals may provide important microbe- and host-based attractants and a basis for future plant-insect-microbe chemical ecology investigations.

Audible acoustics in high-shear wet granulation: application of frequency filtering.

PubMed

Hansuld, Erin M; Briens, Lauren; McCann, Joe A B; Sayani, Amyn

2009-08-13

Previous work has shown analysis of audible acoustic emissions from high-shear wet granulation has potential as a technique for end-point detection. In this research, audible acoustic emissions (AEs) from three different formulations were studied to further develop this technique as a process analytical technology. Condenser microphones were attached to three different locations on a PMA-10 high-shear granulator (air exhaust, bowl and motor) to target different sound sources. Size, flowability and tablet break load data was collected to support formulator end-point ranges and interpretation of AE analysis. Each formulation had a unique total power spectral density (PSD) profile that was sensitive to granule formation and end-point. Analyzing total PSD in 10 Hz segments identified profiles with reduced run variability and distinct maxima and minima suitable for routine granulation monitoring and end-point control. A partial least squares discriminant analysis method was developed to automate selection of key 10 Hz frequency groups using variable importance to projection. The results support use of frequency refinement as a way forward in the development of acoustic emission analysis for granulation monitoring and end-point control.

Development of High Temperature Gas Sensor Technology

NASA Technical Reports Server (NTRS)

Hunter, Gary W.; Chen, Liang-Yu; Neudeck, Philip G.; Knight, Dak; Liu, Chung-Chiun; Wu, Quing-Hai; Zhou, Huan-Jun

1997-01-01

The measurement of engine emissions is important for their monitoring and control. However, the ability to measure these emissions in-situ is limited. We are developing a family of high temperature gas sensors which are intended to operate in harsh environments such as those in an engine. The development of these sensors is based on progress in two types of technology: (1) The development of SiC-based semiconductor technology; and (2) Improvements in micromachining and microfabrication technology. These technologies are being used to develop point-contact sensors to measure gases which are important in emission control especially hydrogen, hydrocarbons, nitrogen oxides, and oxygen. The purpose of this paper is to discuss the development of this point-contact sensor technology. The detection of each type of gas involves its own challenges in the fields of materials science and fabrication technology. Of particular importance is sensor sensitivity, selectivity, and stability in long-term, high temperature operation. An overview is presented of each sensor type with an evaluation of its stage of development. It is concluded that this technology has significant potential for use in engine applications but further development is necessary.

Experimental investigation of homogeneous charge compression ignition combustion of biodiesel fuel with external mixture formation in a CI engine.

PubMed

Ganesh, D; Nagarajan, G; Ganesan, S

2014-01-01

In parallel to the interest in renewable fuels, there has also been increased interest in homogeneous charge compression ignition (HCCI) combustion. HCCI engines are being actively developed because they have the potential to be highly efficient and to produce low emissions. Even though HCCI has been researched extensively, few challenges still exist. These include controlling the combustion at higher loads and the formation of a homogeneous mixture. To obtain better homogeneity, in the present investigation external mixture formation method was adopted, in which the fuel vaporiser was used to achieve excellent HCCI combustion in a single cylinder air-cooled direct injection diesel engine. In continuation of our previous works, in the current study a vaporised jatropha methyl ester (JME) was mixed with air to form a homogeneous mixture and inducted into the cylinder during the intake stroke to analyze the combustion, emission and performance characteristics. To control the early ignition of JME vapor-air mixture, cooled (30 °C) Exhaust gas recirculation (EGR) technique was adopted. The experimental result shows 81% reduction in NOx and 72% reduction in smoke emission.

Atmospheric volatilization of methyl bromide, 1,3-dichloropropene, and propargyl bromide through two plastic films: transfer coefficient and temperature effect

NASA Astrophysics Data System (ADS)

Wang, D.; Yates, S. R.; Gan, J.; Knuteson, J. A.

Atmospheric emission of methyl bromide (MeBr) and its potential alternative chemicals such as 1,3-dichloropropene (1,3-D) and propargyl bromide (PrBr) can contribute to air pollution and ozone depletion (for MeBr). One of the main sources of these chemicals is from agricultural soil fumigation. To understand the volatilization dynamics, emission of MeBr, 1,3-D, and PrBr through a polyethylene-based high-barrier film (HBF) and a virtually impermeable film (VIF) was measured using an air flow and sampling system that produced >90% mass balance. The experiment was conducted outdoors and was subjected to ambient daily temperature variations. The HBF film was found to be very permeable to 1,3-D and PrBr, but somewhat less permeable to MeBr. The VIF film was very impermeable to 1,3-D, PrBr, or MeBr. Measured volatilization flux, in general, exhibited strong diurnal variations which were controlled by film temperature. Unlike the HBF film, a time lag (˜12 h) was observed between high-temperatures and high-emission flux values for the VIF film. An impermeable film may be used as an effective means of controlling the atmospheric emission of MeBr and its alternative chemicals.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tierno, S. P., E-mail: sp.tierno@upm.es; Donoso, J. M.; Domenech-Garret, J. L.

The interaction between an electron emissive wall, electrically biased in a plasma, is revisited through a simple fluid model. We search for realistic conditions of the existence of a non-monotonic plasma potential profile with a virtual cathode as it is observed in several experiments. We mainly focus our attention on thermionic emission related to the operation of emissive probes for plasma diagnostics, although most conclusions also apply to other electron emission processes. An extended Bohm criterion is derived involving the ratio between the two different electron densities at the potential minimum and at the background plasma. The model allows amore » phase-diagram analysis, which confirms the existence of the non-monotonic potential profiles with a virtual cathode. This analysis shows that the formation of the potential well critically depends on the emitted electron current and on the velocity at the sheath edge of cold ions flowing from the bulk plasma. As a consequence, a threshold value of the governing parameter is required, in accordance to the physical nature of the electron emission process. The latter is a threshold wall temperature in the case of thermionic electrons. Experimental evidence supports our numerical calculations of this threshold temperature. Besides this, the potential well becomes deeper with increasing electron emission, retaining a fraction of the released current which limits the extent of the bulk plasma perturbation. This noninvasive property would explain the reliable measurements of plasma potential by using the floating potential method of emissive probes operating in the so-called strong emission regime.« less

Lead Emissions and Population Vulnerability in the Detroit (Michigan, USA) Metropolitan Area, 2006-2013: A Spatial and Temporal Analysis.

PubMed

Moody, Heather; Grady, Sue C

2017-11-23

Objective : The purpose of this research is to geographically model airborne lead emission concentrations and total lead deposition in the Detroit Metropolitan Area (DMA) from 2006 to 2013. Further, this study characterizes the racial and socioeconomic composition of recipient neighborhoods and estimates the potential for IQ (Intelligence Quotient) loss of children residing there. Methods : Lead emissions were modeled from emitting facilities in the DMA using AERMOD (American Meteorological Society/Environmental Protection Agency Regulatory Model). Multilevel modeling was used to estimate local racial residential segregation, controlling for poverty. Global Moran's I bivariate spatial autocorrelation statistics were used to assess modeled emissions with increasing segregation. Results : Lead emitting facilities were primarily located in, and moving to, highly black segregated neighborhoods regardless of poverty levels-a phenomenon known as environmental injustice. The findings from this research showed three years of elevated airborne emission concentrations in these neighborhoods to equate to a predicted 1.0 to 3.0 reduction in IQ points for children living there. Across the DMA there are many areas where annual lead deposition was substantially higher than recommended for aquatic (rivers, lakes, etc.) and terrestrial (forests, dunes, etc.) ecosystems. These lead levels result in decreased reproductive and growth rates in plants and animals, and neurological deficits in vertebrates. Conclusions : This lead-hazard and neighborhood context assessment will inform future childhood lead exposure studies and potential health consequences in the DMA.

40 CFR 59.664 - What are the requirements for importing portable fuel containers into the United States?

Code of Federal Regulations, 2010 CFR

2010-07-01

... STANDARDS FOR CONSUMER AND COMMERCIAL PRODUCTS Control of Evaporative Emissions From New and In-Use Portable Fuel Containers Special Compliance Provisions § 59.664 What are the requirements for importing portable... bond to cover any potential compliance or enforcement actions under the Clean Air Act if you cannot...

Monoterpene emissions from an understory species, Pteridium aquilinum

NASA Astrophysics Data System (ADS)

Madronich, Monica B.; Greenberg, James P.; Wessman, Carol A.; Guenther, Alex B.

2012-07-01

Monoterpene emissions from the dominant understory species Pteridium aquilinum (Bracken fern) in a mixed temperate forest were measured in the field during the summers of 2006, 2007 and 2008. The results showed that Bracken fern emitted monoterpenes at different rates depending if the plants were located in the understory or in open areas. Understory plants emitted monoterpene levels ranging from 0.002 to 13 μgC gdw-1 h-1. Open area plants emitted monoterpene levels ranging from 0.005 to 2.21 μgC gdw-1 h-1. During the summer of 2008 greenhouse studies were performed to complement the field studies. Only 3% of the greenhouse Bracken fern plants emitted substantial amounts of monoterpenes. The average emission, 0.15 μgC gdw-1 h-1 ± 0.9 μgC gdw-1 h-1, was much lower than that observed in the field. The factors controlling monoterpene emissions are not clear, but this study provides evidence of the potential importance of understory vegetation to ecosystem total hydrocarbon emissions and emphasizes the need for longer-term field studies.

Long term plant biomonitoring in the vicinity of waste incinerators in The Netherlands.

PubMed

van Dijk, Chris; van Doorn, Wim; van Alfen, Bert

2015-03-01

Since the mid-nineties new waste incineration plants have come into operation in the Netherlands. Burning of waste can result in the emission of potentially toxic compounds. Although the incineration plants must comply with strict conditions concerning emission control, public concern on the possible impact on human health and the environment still exists. Multiple year (2004-2013) biomonitoring programs were set up around three waste incinerators for early detection of possible effects of stack emissions on the quality of crops and agricultural products. The results showed that the emissions did not affect the quality of crops and cow milk. Concentrations of heavy metals, PAHs and dioxins/PCBs were generally similar to background levels and did not exceed standards for maximum allowable concentrations in foodstuffs (e.g. vegetables and cow milk). Some exceedances of the fluoride standard for cattle feed were found almost every year in the maximum deposition areas of two incinerators. Biomonitoring with leafy vegetables can be used to monitor the real impact of these emissions on agricultural crops and to communicate with all stakeholders. Copyright © 2014 Elsevier Ltd. All rights reserved.

Quantification of Methane and Ammonia Emissions in a Naturally Ventilated Barn by Using Defined Criteria to Calculate Emission Rates.

PubMed

Schmithausen, Alexander J; Schiefler, Inga; Trimborn, Manfred; Gerlach, Katrin; Südekum, Karl-Heinz; Pries, Martin; Büscher, Wolfgang

2018-05-16

Extensive experimentation on individual animals in respiration chambers has already been carried out to evaluate the potential of dietary changes and opportunities to mitigate CH₄ emissions from ruminants. Although it is difficult to determine the air exchange rate of open barn spaces, measurements at the herd level should provide similarly reliable and robust results. The primary objective of this study was (1) to define a validity range (data classification criteria (DCC)) for the variables of wind velocity and wind direction during long-term measurements at barn level; and (2) to apply this validity range to a feeding trial in a naturally cross-flow ventilated dairy barn. The application of the DCC permitted quantification of CH₄ and NH₃ emissions during a feeding trial consisting of four periods. Differences between the control group (no supplement) and the experimental group fed a ration supplemented with condensed Acacia mearnsii tannins (CT) became apparent. Notably, CT concentrations of 1% and 3% of ration dry matter did not reduce CH₄ emissions. In contrast, NH₃ emissions decreased 34.5% when 3% CT was supplemented. The data confirm that quantification of trace gases in a naturally ventilated barn at the herd level is possible.

Atlantic ocean surface waters buffer declining atmospheric concentrations of persistent organic pollutants.

PubMed

Nizzetto, Luca; Lohmann, Rainer; Gioia, Rosalinda; Dachs, Jordi; Jones, Kevin C

2010-09-15

Decreasing environmental concentrations of some persistent organic pollutants (POPs) have been observed at local or regional scales in continental areas after the implementation of international measures to curb primary emissions. A decline in primary atmospheric emissions can result in re-emissions of pollutants from the environmental capacitors (or secondary sources) such as soils and oceans. This may be part of the reason why concentrations of some POPs such as polychlorinated biphenyls (PCBs) have not declined significantly in the open oceanic areas, although re-emission of POPs from open ocean water has barely been documented. In contrast, results from this study show that several polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) have undergone a marked decline (2-3 orders of magnitude for some homologues) over a major portion of the remote oligotrophic Atlantic Ocean. The decline appears to be faster than that observed over continental areas, implicating an important role of oceanic geochemical controls on levels and cycling of some POPs. For several lower chlorinated PCDD/Fs, we observed re-emission from surface water back to the atmosphere. An assessment of the effectiveness of the main sink processes highlights the role of degradation in surface waters as potentially key to explaining the different behavior between PCDD/Fs and PCBs and controlling their overall residence time in the ocean/atmosphere system. This study provides experimental evidence that the ocean has a buffering capacity - dependent on individual chemicals - which moderates the rate at which the system will respond to an underlying change in continental emissions.

Spectral and angular-selective thermal emission from gallium-doped zinc oxide thin film structures

NASA Astrophysics Data System (ADS)

Sakr, Enas; Bermel, Peter

2017-02-01

Simultaneously controlling both the spectral and angular emission of thermal photons can qualitatively change the nature of thermal radiation, and offers a great potential to improve a broad range of applications, including infrared light sources and thermophotovoltaic (TPV) conversion of waste heat to electricity. For TPV in particular, frequency-selective emission is necessary for spectral matching with a photovoltaic converter, while directional emission is needed to maximize the fraction of emission reaching the receiver at large separation distances. This can allow the photovoltaics to be moved outside vacuum encapsulation. In this work, we demonstrate both directionally and spectrally-selective thermal emission for p-polarization, using a combination of an epsilon-near-zero (ENZ) thin film backed by a metal reflector, a high contrast grating, and an omnidirectional mirror. Gallium-doped zinc oxide is selected as an ENZ material, with cross-over frequency in the near-infrared. The proposed structure relies on coupling guided modes (instead of plasmonic modes) to the ENZ thin film using the high contrast grating. The angular width is thus controlled by the choice of grating period. Other off-directional modes are then filtered out using the omnidirectional mirror, thus enhancing frequency selectivity. Our emitter design maintains both a high view factor and high frequency selectivity, leading to a factor of 8.85 enhancement over a typical blackbody emitter, through a combination of a 22.26% increase in view factor and a 6.88x enhancement in frequency selectivity. This calculation assumes a PV converter five widths away from the same width emitter in 2D at 1573 K.

MEMS Louvers for Thermal Control

NASA Technical Reports Server (NTRS)

Champion, J. L.; Osiander, R.; Darrin, M. A. Garrison; Swanson, T. D.

1998-01-01

Mechanical louvers have frequently been used for spacecraft and instrument thermal control purposes. These devices typically consist of parallel or radial vanes, which can be opened or closed to vary the effective emissivity of the underlying surface. This project demonstrates the feasibility of using Micro-Electromechanical Systems (MEMS) technology to miniaturize louvers for such purposes. This concept offers the possibility of substituting the smaller, lighter weight, more rugged, and less costly MEMS devices for such mechanical louvers. In effect, a smart skin that self adjusts in response to environmental influences could be developed composed of arrays of thousands of miniaturized louvers. Several orders of magnitude size, weight, and volume decreases are potentially achieved using micro-electromechanical techniques. The use of this technology offers substantial benefits in spacecraft/instrument design, integration and testing, and flight operations. It will be particularly beneficial for the emerging smaller spacecraft and instruments of the future. In addition, this MEMS thermal louver technology can form the basis for related spacecraft instrument applications. The specific goal of this effort was to develop a preliminary MEMS device capable of modulating the effective emissivity of radiators on spacecraft. The concept pursued uses hinged panels, or louvers, in a manner such that heat emitted from the radiators is a function of louver angle. An electrostatic comb drive or other such actuator can control the louver position. The initial design calls for the louvers to be gold coated while the underlying surface is of high emissivity. Since, the base MEMS material, silicon, is transparent in the InfraRed (IR) spectrum, the device has a minimum emissivity when closed and a maximum emissivity when open. An initial set of polysilicon louver devices was designed at the Johns Hopkins Applied Physics Laboratory in conjunction with the Thermal Engineering Branch at NASA's Goddard Space Flight Center.

A technical, economic, and environmental assessment of amine-based CO2 capture technology for power plant greenhouse gas control.

PubMed

Rao, Anand B; Rubin, Edward S

2002-10-15

Capture and sequestration of CO2 from fossil fuel power plants is gaining widespread interest as a potential method of controlling greenhouse gas emissions. Performance and cost models of an amine (MEA)-based CO2 absorption system for postcombustion flue gas applications have been developed and integrated with an existing power plant modeling framework that includes multipollutant control technologies for other regulated emissions. The integrated model has been applied to study the feasibility and cost of carbon capture and sequestration at both new and existing coal-burning power plants. The cost of carbon avoidance was shown to depend strongly on assumptions about the reference plant design, details of the CO2 capture system design, interactions with other pollution control systems, and method of CO2 storage. The CO2 avoidance cost for retrofit systems was found to be generally higher than for new plants, mainly because of the higher energy penalty resulting from less efficient heat integration as well as site-specific difficulties typically encountered in retrofit applications. For all cases, a small reduction in CO2 capture cost was afforded by the SO2 emission trading credits generated by amine-based capture systems. Efforts are underway to model a broader suite of carbon capture and sequestration technologies for more comprehensive assessments in the context of multipollutant environmental management.

Effect of Corn Dried Distiller Grains with Solubles (DDGS) in Dairy Cow Diets on Manure Bioenergy Production Potential

PubMed Central

Massé, Daniel I.; Jarret, Guillaume; Benchaar, Chaouki; Saady, Noori M. Cata

2014-01-01

Simple Summary Among the measures proposed to reduce environmental pollution from the livestock sector, animal nutrition has a strong potential to reduce enteric and manure storages methane emissions. Changes in diet composition also affect the bioenergy potential of dairy manures. Corn dried distillers grains with solubles (DDGS), which are rich in fat, can be included in animal diets to reduce enteric methane (CH4) emissions, while increasing the bioenergy potential of the animal manure during anaerobic digestion. The inclusion of 30% DDGS in the cow diet caused a significant increase of 14% in daily bioenergy production (NL methane day−1·cow−1). abstract The main objective of this study was to obtain scientifically sound data on the bioenergy potential of dairy manures from cows fed different levels of corn dried distillers grains with solubles (DDGS). Three diets differing in corn DDGS content were formulated: 0% corn DDGS (DDGS0; control diet), 10% corn DDGS (DDGS10) and 30% corn DDGS (DDGS30). Bioenergy production was determined in psychrophilic (25 ± 1 °C) sequencing batch reactors (SBRs) fed 3 g COD L−1·day−1 during a two-week feeding period followed by a two-week react period. Compared to the control diet, adding DDGS10 and DDGS30 to the dairy cow diet increased the daily amount of fat excreted in slurry by 29% and 70%, respectively. The addition of DDGS30 increased the cows’ daily production of fresh feces and slurry by 15% and 11%, respectively. Furthermore, the incorporation of DDGS30 in the diet increased the daily amounts of dry matter (DM), volatile solids (VS), neutral detergent fiber (NDF), acid detergent fiber (ADF) and hemicellulose by 18%, 18%, 30%, 15% and 53%, respectively, compared to the control diet. While the addition of DDGS did not significantly affect the specific CH4 production per kg VS compared to the control diet, DDGS30 increased the per cow daily CH4 production by 14% compared to the control diet. PMID:26479885

40 CFR 86.1803-01 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... which are designed primarily for emission control, or whose failure may result in a significant increase... waiver of emission data submission requirements under § 86.1829-01. Element of design means any control... a motor vehicle or motor vehicle engine. Emission control system is a unique group of emission...

40 CFR 94.211 - Emission-related maintenance instructions for purchasers.

Code of Federal Regulations, 2014 CFR

2014-07-01

... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM MARINE COMPRESSION-IGNITION ENGINES..., replacement, or repair of the emission control devices and systems may be performed by any engine repair... and necessary to ensure the proper functioning of the engine's emission control systems. If the...

40 CFR 94.211 - Emission-related maintenance instructions for purchasers.

Code of Federal Regulations, 2012 CFR

2012-07-01

... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM MARINE COMPRESSION-IGNITION ENGINES..., replacement, or repair of the emission control devices and systems may be performed by any engine repair... and necessary to ensure the proper functioning of the engine's emission control systems. If the...

40 CFR 94.211 - Emission-related maintenance instructions for purchasers.

Code of Federal Regulations, 2013 CFR

2013-07-01

... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM MARINE COMPRESSION-IGNITION ENGINES..., replacement, or repair of the emission control devices and systems may be performed by any engine repair... and necessary to ensure the proper functioning of the engine's emission control systems. If the...

Reports related to Emissions Control Areas for Marine Vessels

EPA Pesticide Factsheets

Reports related to Marine Emissions Control Areas including Global Trade and Fuels Assessment, Modeling Sulfur Oxides Emissions Transport From Ships at Sea, Commercial Marine Emission Inventory Development

40 CFR 63.3555 - How do I determine the outlet THC emissions and add-on control device emission destruction or...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 12 2010-07-01 2010-07-01 true How do I determine the outlet THC.../outlet Concentration Option § 63.3555 How do I determine the outlet THC emissions and add-on control... section to determine either the outlet THC emissions or add-on control device emission destruction or...

40 CFR 63.3555 - How do I determine the outlet THC emissions and add-on control device emission destruction or...

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 13 2013-07-01 2012-07-01 true How do I determine the outlet THC... Control Efficiency/outlet Concentration Option § 63.3555 How do I determine the outlet THC emissions and... methods in this section to determine either the outlet THC emissions or add-on control device emission...

40 CFR 63.3555 - How do I determine the outlet THC emissions and add-on control device emission destruction or...

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 13 2014-07-01 2014-07-01 false How do I determine the outlet THC... Control Efficiency/outlet Concentration Option § 63.3555 How do I determine the outlet THC emissions and... methods in this section to determine either the outlet THC emissions or add-on control device emission...

40 CFR 63.3555 - How do I determine the outlet THC emissions and add-on control device emission destruction or...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 12 2011-07-01 2009-07-01 true How do I determine the outlet THC.../outlet Concentration Option § 63.3555 How do I determine the outlet THC emissions and add-on control... section to determine either the outlet THC emissions or add-on control device emission destruction or...

40 CFR 63.3555 - How do I determine the outlet THC emissions and add-on control device emission destruction or...

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 13 2012-07-01 2012-07-01 false How do I determine the outlet THC... Control Efficiency/outlet Concentration Option § 63.3555 How do I determine the outlet THC emissions and... methods in this section to determine either the outlet THC emissions or add-on control device emission...

40 CFR 75.19 - Optional SO2, NOX, and CO2 emissions calculation for low mass emissions (LME) units.

Code of Federal Regulations, 2011 CFR

2011-07-01

... (or group of identical units) equipped with SCR (or SNCR) and uses dry low-NOX technology to control... with add-on NOX emission controls, and for units that use dry low-NOX technology, the owner or operator... mass emissions unit that uses dry low-NOX premix technology to control NOX emissions, proper operation...

77 FR 45337 - U.S. Environmental Solutions Toolkit

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-31

... services relevant to (a) groundwater remediation; (b) mercury emissions control from power plants; (c...) Groundwater remediation (b) Mercury emissions control from power plants (c) Emissions control from large...

Active Pattern Factor Control for Gas Turbine Engines

NASA Technical Reports Server (NTRS)

May, James E.

1998-01-01

Small variations in fuel/air mixture ratios within gas turbine combustors can result in measurable, and potentially detrimental, exit thermal gradients. Thermal gradients can increase emissions, as well as shorten the design life of downstream turbomachinery, particularly stator vanes. Uniform temperature profiles are usually sought through careful design and manufacturing of related combustor components. However, small componentto-component variations as well as numerous aging effects degrade system performance. To compensate for degraded thermal performance, researchers are investigating active, closed-loop control schemes.

40 CFR 1054.205 - What must I include in my application?

Code of Federal Regulations, 2012 CFR

2012-07-01

... emission family's specifications and other basic parameters of the engine's design and emission controls. List the fuel type on which your engines are designed to operate (for example, all-season gasoline... emission control systems operate. Describe the evaporative emission controls and show how your design will...

40 CFR 1054.205 - What must I include in my application?

Code of Federal Regulations, 2011 CFR

2011-07-01

... emission family's specifications and other basic parameters of the engine's design and emission controls. List the fuel type on which your engines are designed to operate (for example, all-season gasoline... emission control systems operate. Describe the evaporative emission controls and show how your design will...

40 CFR 1054.205 - What must I include in my application?

Code of Federal Regulations, 2010 CFR

2010-07-01

... emission family's specifications and other basic parameters of the engine's design and emission controls. List the fuel type on which your engines are designed to operate (for example, all-season gasoline... emission control systems operate. Describe the evaporative emission controls and show how your design will...

40 CFR 1054.205 - What must I include in my application?

Code of Federal Regulations, 2013 CFR

2013-07-01

... emission family's specifications and other basic parameters of the engine's design and emission controls. List the fuel type on which your engines are designed to operate (for example, all-season gasoline... emission control systems operate. Describe the evaporative emission controls and show how your design will...

40 CFR 1054.205 - What must I include in my application?

Code of Federal Regulations, 2014 CFR

2014-07-01

... emission family's specifications and other basic parameters of the engine's design and emission controls. List the fuel type on which your engines are designed to operate (for example, all-season gasoline... emission control systems operate. Describe the evaporative emission controls and show how your design will...

40 CFR 63.1332 - Emissions averaging provisions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... other controls for a Group 1 storage vessel, batch process vent, aggregate batch vent stream, continuous... in control after November 15, 1990. (2) Group 1 emission points, identified in paragraph (c)(3) of... applicable reference control technology or standard and the emissions allowed for the Group 1 emission point...

40 CFR 63.1332 - Emissions averaging provisions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... other controls for a Group 1 storage vessel, batch process vent, aggregate batch vent stream, continuous... in control after November 15, 1990. (2) Group 1 emission points, identified in paragraph (c)(3) of... reference control technology or standard and the emissions allowed for the Group 1 emission point. Said...

40 CFR 1060.104 - What running loss emission control requirements apply?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false What running loss emission control... STATIONARY EQUIPMENT Emission Standards and Related Requirements § 1060.104 What running loss emission control requirements apply? (a) Engines and equipment must meet running loss requirements as follows: (1...

40 CFR 1060.525 - How do I test fuel systems for diurnal emissions?

Code of Federal Regulations, 2010 CFR

2010-07-01

... fuel tanks, and volume-compensating air bags. (b) You may subtract your fuel tank's permeation...) AIR POLLUTION CONTROLS CONTROL OF EVAPORATIVE EMISSIONS FROM NEW AND IN-USE NONROAD AND STATIONARY... diurnal emission standard. (8) For emission control technologies that rely on a sealed fuel system, you...

40 CFR 1060.525 - How do I test fuel systems for diurnal emissions?

Code of Federal Regulations, 2011 CFR

2011-07-01

... fuel tanks, and volume-compensating air bags. (b) You may subtract your fuel tank's permeation...) AIR POLLUTION CONTROLS CONTROL OF EVAPORATIVE EMISSIONS FROM NEW AND IN-USE NONROAD AND STATIONARY... diurnal emission standard. (8) For emission control technologies that rely on a sealed fuel system, you...

Effect of irrigation, nitrogen application, and a nitrification inhibitor on nitrous oxide, carbon dioxide and methane emissions from an olive (Olea europaea L.) orchard.

PubMed

Maris, S C; Teira-Esmatges, M R; Arbonés, A; Rufat, J

2015-12-15

Drip irrigation combined with nitrogen (N) fertigation is applied in order to save water and improve nutrient efficiency. Nitrification inhibitors reduce greenhouse gas emissions. A field study was conducted to compare the emissions of nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) associated with the application of N fertiliser through fertigation (0 and 50kgNha(-1)), and 50kgNha(-1)+nitrification inhibitor in a high tree density Arbequina olive orchard. Spanish Arbequina is the most suited variety for super intensive olive groves. This system allows reducing production costs and increases crop yield. Moreover its oil has excellent sensorial features. Subsurface drip irrigation markedly reduced N2O and N2O+N2 emissions compared with surface drip irrigation. Fertiliser application significantly increased N2O+N2, but not N2O emissions. Denitrification was the main source of N2O. The N2O losses (calculated as emission factor) ranging from -0.03 to 0.14% of the N applied, were lower than the IPCC (2007) values. The N2O+N2 losses were the largest, equivalent to 1.80% of the N applied, from the 50kgNha(-1)+drip irrigation treatment which resulted in water filled pore space >60% most of the time (high moisture). Nitrogen fertilisation significantly reduced CO2 emissions in 2011, but only for the subsurface drip irrigation strategies in 2012. The olive orchard acted as a net CH4 sink for all the treatments. Applying a nitrification inhibitor (DMPP), the cumulative N2O and N2O+N2 emissions were significantly reduced with respect to the control. The DMPP also inhibited CO2 emissions and significantly increased CH4 oxidation. Considering global warming potential, greenhouse gas intensity, cumulative N2O emissions and oil production, it can be concluded that applying DMPP with 50kgNha(-1)+drip irrigation treatment was the best option combining productivity with keeping greenhouse gas emissions under control. Copyright © 2015 Elsevier B.V. All rights reserved.

Viewing the effects of anthropogenic emission control from the change of CO2 concentration observed by GOSAT in China during the 2014 APEC summit

NASA Astrophysics Data System (ADS)

Lei, L.; Zhong, H.; Liu, L.; Yang, S., Sr.

2016-12-01

The growth of the global anthropogenic carbon emission stalled in 2014, according to data from International Energy Agency (IEA). This paper presents a practical application of satellite observation for detecting the regional enhancement of CO2 induced by underlying anthropogenic CO2 emissions especially during the 2014 Asia-Pacific Economic Cooperation (APEC) summit. We collected the column averaged dry air mole fraction (XCO2) data from Greenhouse Observation SATellite (GOSAT) from Jan. 2010 to Dec. 2015, which are provided by Japan GOSAT project team. The spatial change of the 5-year averaged XCO2 derived by gap filling [Zeng et al., TGRS, 2014], as shown in Fig.1, demonstrated that high XCO2prefer to correspond to the most intensive power plants. We calculated the regional contrasts between source and almost without emission (Fig.2), which are defined based on emission and potential temperature. The source, which is defined around Beijing, has many big power plants (Fig.1). The regional contrast showed 1-3 ppm with large seasonal variations while it is the lowest in summer due to influence of biospheric fluxes and especially show abnormal fluctuation in autumn 2014 (Fig.3). XCO2 fell from 398.9 ppm in 15-30 Oct. before APEC to 395.7 ppm during 1-11 Nov. 2014 APEC in source area around Beijing, and the contrast decreased from 4.5 ppm to 1.0 ppm (Table 1). This abnormal decline of XCO2 likely indicate the effects of controlling action for strong local source emissions such as closed many small inefficient coal-fired power plants from the beginning of 2014, banned on burning straw, especially in addition to temporally shut down the big coal-power plants and limiting the number of vehicles running during the APEC summit within the large zone covering the six provinces around Beijing. The large reduction was reported in aerosol of 50% above during the APEC summit (Sun et al., Sci. report, 2016). Our results agree to the potential of satellite observations to contribute to the verification of the reported anthropogenic CO2 emissions discussed in Keppel-Aleks et al. (ACP, 2013). Acknowledgement: We are greatly acknowledging the data products provided by NIES GOSAT Project and CARMA.

40 CFR 1039.801 - What definitions apply to this part?

Code of Federal Regulations, 2014 CFR

2014-07-01

... operation in water. Auxiliary emission-control device means any element of design that senses temperature... suppression operations. Emission-control system means any device, system, or element of design that controls... POLLUTION CONTROLS CONTROL OF EMISSIONS FROM NEW AND IN-USE NONROAD COMPRESSION-IGNITION ENGINES Definitions...

Modeling Impacts of Alternative Practices on Net Global Warming Potential and Greenhouse Gas Intensity from Rice–Wheat Annual Rotation in China

PubMed Central

Wang, Jinyang; Zhang, Xiaolin; Liu, Yinglie; Pan, Xiaojian; Liu, Pingli; Chen, Zhaozhi; Huang, Taiqing; Xiong, Zhengqin

2012-01-01

Background Evaluating the net exchange of greenhouse gas (GHG) emissions in conjunction with soil carbon sequestration may give a comprehensive insight on the role of agricultural production in global warming. Materials and Methods Measured data of methane (CH4) and nitrous oxide (N2O) were utilized to test the applicability of the Denitrification and Decomposition (DNDC) model to a winter wheat – single rice rotation system in southern China. Six alternative scenarios were simulated against the baseline scenario to evaluate their long-term (45-year) impacts on net global warming potential (GWP) and greenhouse gas intensity (GHGI). Principal Results The simulated cumulative CH4 emissions fell within the statistical deviation ranges of the field data, with the exception of N2O emissions during rice-growing season and both gases from the control treatment. Sensitivity tests showed that both CH4 and N2O emissions were significantly affected by changes in both environmental factors and management practices. Compared with the baseline scenario, the long-term simulation had the following results: (1) high straw return and manure amendment scenarios greatly increased CH4 emissions, while other scenarios had similar CH4 emissions, (2) high inorganic N fertilizer increased N2O emissions while manure amendment and reduced inorganic N fertilizer scenarios decreased N2O emissions, (3) the mean annual soil organic carbon sequestration rates (SOCSR) under manure amendment, high straw return, and no-tillage scenarios averaged 0.20 t C ha−1 yr−1, being greater than other scenarios, and (4) the reduced inorganic N fertilizer scenario produced the least N loss from the system, while all the scenarios produced comparable grain yields. Conclusions In terms of net GWP and GHGI for the comprehensive assessment of climate change and crop production, reduced inorganic N fertilizer scenario followed by no-tillage scenario would be advocated for this specified cropping system. PMID:23029173

Microfabricated Chemical Sensors for Safety and Emission Control Applications

NASA Technical Reports Server (NTRS)

Hunter, G. W.; Neudeck, P. G.; Chen, L.-Y.; Knight, D.; Liu, C. C.; Wu, Q. H.

1998-01-01

Chemical sensor technology is being developed for leak detection, emission monitoring, and fire safety applications. The development of these sensors is based on progress in two types of technology: 1) Micromachining and microfabrication (MicroElectroMechanical Systems (MEMS)-based) technology to fabricate miniaturized sensors. 2) The development of high temperature semiconductors, especially silicon carbide. Using these technologies, sensors to measure hydrogen, hydrocarbons, nitrogen oxides, carbon monoxide, oxygen, and carbon dioxide are being developed. A description is given of each sensor type and its present stage of development. It is concluded that microfabricated sensor technology has significant potential for use in a range of aerospace applications.

A Probabilistic System Analysis of Intelligent Propulsion System Technologies

NASA Technical Reports Server (NTRS)

Tong, Michael T.

2007-01-01

NASA s Intelligent Propulsion System Technology (Propulsion 21) project focuses on developing adaptive technologies that will enable commercial gas turbine engines to produce fewer emissions and less noise while increasing reliability. It features adaptive technologies that have included active tip-clearance control for turbine and compressor, active combustion control, turbine aero-thermal and flow control, and enabling technologies such as sensors which are reliable at high operating temperatures and are minimally intrusive. A probabilistic system analysis is performed to evaluate the impact of these technologies on aircraft CO2 (directly proportional to fuel burn) and LTO (landing and takeoff) NO(x) reductions. A 300-passenger aircraft, with two 396-kN thrust (85,000-pound) engines is chosen for the study. The results show that NASA s Intelligent Propulsion System technologies have the potential to significantly reduce the CO2 and NO(x) emissions. The results are used to support informed decisionmaking on the development of the intelligent propulsion system technology portfolio for CO2 and NO(x) reductions.

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

Reversed oxygen sensing using colloidal quantum wells towards highly emissive photoresponsive varnishes

PubMed Central

Lorenzon, Monica; Christodoulou, Sotirios; Vaccaro, Gianfranco; Pedrini, Jacopo; Meinardi, Francesco; Moreels, Iwan; Brovelli, Sergio

2015-01-01

Colloidal quantum wells combine the advantages of size-tunable electronic properties with vast reactive surfaces that could allow one to realize highly emissive luminescent-sensing varnishes capable of detecting chemical agents through their reversible emission response, with great potential impact on life sciences, environmental monitoring, defence and aerospace engineering. Here we combine spectroelectrochemical measurements and spectroscopic studies in a controlled atmosphere to demonstrate the ‘reversed oxygen-sensing’ capability of CdSe colloidal quantum wells, that is, the exposure to oxygen reversibly increases their luminescence efficiency. Spectroelectrochemical experiments allow us to directly relate the sensing response to the occupancy of surface states. Magneto-optical measurements demonstrate that, under vacuum, heterostructured CdSe/CdS colloidal quantum wells stabilize in their negative trion state. The high starting emission efficiency provides a possible means to enhance the oxygen sensitivity by partially de-passivating the particle surfaces, thereby enhancing the density of unsaturated sites with a minimal cost in term of luminescence losses. PMID:25910499

In-situ acoustic signature monitoring in additive manufacturing processes

NASA Astrophysics Data System (ADS)

Koester, Lucas W.; Taheri, Hossein; Bigelow, Timothy A.; Bond, Leonard J.; Faierson, Eric J.

2018-04-01

Additive manufacturing is a rapidly maturing process for the production of complex metallic, ceramic, polymeric, and composite components. The processes used are numerous, and with the complex geometries involved this can make quality control and standardization of the process and inspection difficult. Acoustic emission measurements have been used previously to monitor a number of processes including machining and welding. The authors have identified acoustic signature measurement as a potential means of monitoring metal additive manufacturing processes using process noise characteristics and those discrete acoustic emission events characteristic of defect growth, including cracks and delamination. Results of acoustic monitoring for a metal additive manufacturing process (directed energy deposition) are reported. The work investigated correlations between acoustic emissions and process noise with variations in machine state and deposition parameters, and provided proof of concept data that such correlations do exist.

Radio-Frequency-Controlled Urea Dosing for NH3-SCR Catalysts: NH3 Storage Influence to Catalyst Performance under Transient Conditions

PubMed Central

Dietrich, Markus; Hagen, Gunter; Reitmeier, Willibald; Burger, Katharina; Hien, Markus; Grass, Philippe; Kubinski, David; Visser, Jaco; Moos, Ralf

2017-01-01

Current developments in exhaust gas aftertreatment led to a huge mistrust in diesel driven passenger cars due to their NOx emissions being too high. The selective catalytic reduction (SCR) with ammonia (NH3) as reducing agent is the only approach today with the capability to meet upcoming emission limits. Therefore, the radio-frequency-based (RF) catalyst state determination to monitor the NH3 loading on SCR catalysts has a huge potential in emission reduction. Recent work on this topic proved the basic capability of this technique under realistic conditions on an engine test bench. In these studies, an RF system calibration for the serial type SCR catalyst Cu-SSZ-13 was developed and different approaches for a temperature dependent NH3 storage were determined. This paper continues this work and uses a fully calibrated RF-SCR system under transient conditions to compare different directly measured and controlled NH3 storage levels, and NH3 target curves. It could be clearly demonstrated that the right NH3 target curve, together with a direct control on the desired level by the RF system, is able to operate the SCR system with the maximum possible NOx conversion efficiency and without NH3 slip. PMID:29182589

Prescribed fire as a means of reducing forest carbon emissions in the western United States.

PubMed

Wiedinmyer, Christine; Hurteau, Matthew D

2010-03-15

Carbon sequestration by forested ecosystems offers a potential climate change mitigation benefit. However, wildfire has the potential to reverse this benefit In the western United States, climate change and land management practices have led to increases in wildfire intensity and size. One potential means of reducing carbon emissions from wildfire is the use of prescribed burning,which consumes less biomass and therefore releases less carbon to the atmosphere. This study uses a regional fire emissions model to estimate the potential reduction in fire emissions when prescribed burning is applied in dry, temperate forested systems of the western U.S. Daily carbon dioxide (CO(2)) fire emissions for 2001-2008 were calculated for the western U.S. for two cases: a default wildfire case and one in which prescribed burning was applied. Wide-scale prescribed fire application can reduce CO(2) fire emissions for the western U.S. by 18-25%1 in the western U.S., and by as much as 60% in specific forest systems. Although this work does not address important considerations such as the feasibility of implementing wide-scale prescribed fire management or the cumulative emissions from repeated prescribed burning, it does provide constraints on potential carbon emission reductions when prescribed burning is used.

Variations in the methane budget over the last two millennia

NASA Astrophysics Data System (ADS)

Derendorp, L.

2012-06-01

Leaf litter is available at the Earth’s surface in large quantities. During the decomposition of leaf litter, volatile compounds can be released into the atmosphere, where they potentially influence local air quality, atmospheric chemistry or the global climate. In this thesis the focus was on the emission of C2-C5 hydrocarbons, molecular hydrogen (H2), carbon monoxide (CO) and methyl chloride (CH3Cl) from leaf litter and the factors that control the emissions were investigated. For different plant species, the emission rates of several C2-C5 hydrocarbons increased with temperature between 20 and 100°C according to the Arrhenius relation. When leaf litter was irradiated with UV, the emission increased linearly with the intensity of the UV. UVB radiation was more efficient in the generation of hydrocarbons from leaf litter than UVA. A simple upscaling showed that C2-C5 hydrocarbon emissions from leaf litter are likely insignificant for their global budgets, but may have a small influence on atmospheric chemistry on the local scale. Senescent and dead plant material releases carbon monoxide (CO), methane and larger hydrocarbons upon heating or irradiation with UV, but emissions of hydrogen (H2) have not been reported. In this study, H2 was released from leaf litter of Sequoiadendron giganteum in detectable amounts at temperatures above 45°C, whereas CO was also emitted at ambient temperature. Leaf litter has been identified as a potentially important source of CH3Cl. However, the factors controlling the emissions are unclear. Laboratory experiments have been performed in which CH3Cl emissions were measured from leaf litter of different plant species. For each investigated plant species, the CH3Cl emission rate strongly increased with temperature according to the Arrhenius relation. However, at constant temperature, large differences between different plants were observed. Therefore, CH3Cl emissions were measured from halophyte leaf litter with a varying chloride content, but no significant correlation between the CH3Cl emission rate and the chloride content of the plant material was observed. A limited set of field experiments was performed in which CH3Cl emissions were measured. Leaf litter emitted CH3Cl, but only in periods with fresh leaf litter fall. Outside these periods, the flux from leaf litter was zero or even slightly negative. The CH3Cl emission rate increased with temperature, but the temperature increase did not follow the Arrhenius relation as was observed in the laboratory experiments. The global importance of leaf litter as a source of CH3Cl was investigated using the global chemistry transport model TM5. Forward simulations with different emission scenarios indicated that at station Trinidad Head (mid-latitudes of North America), a substantial seasonal emission from leaf litter was required to match the measured CH3Cl mixing ratios at this station. Inversions performed with the TM4-4D-Var system indicated that the main CH3Cl sources were located in the Tropics, whereas the mid- and high latitudes were only a minor source. Sensitivity studies performed to investigate the robustness of the optimized emissions indicated that more than 90% of the global net emissions was located in the Tropics.

GaAs1-xBix/GaNyAs1-y type-II quantum wells: novel strain-balanced heterostructures for GaAs-based near- and mid-infrared photonics.

PubMed

Broderick, Christopher A; Jin, Shirong; Marko, Igor P; Hild, Konstanze; Ludewig, Peter; Bushell, Zoe L; Stolz, Wolfgang; Rorison, Judy M; O'Reilly, Eoin P; Volz, Kerstin; Sweeney, Stephen J

2017-04-19

The potential to extend the emission wavelength of photonic devices further into the near- and mid-infrared via pseudomorphic growth on conventional GaAs substrates is appealing for a number of communications and sensing applications. We present a new class of GaAs-based quantum well (QW) heterostructure that exploits the unusual impact of Bi and N on the GaAs band structure to produce type-II QWs having long emission wavelengths with little or no net strain relative to GaAs, while also providing control over important laser loss processes. We theoretically and experimentally demonstrate the potential of GaAs 1-x Bi x /GaN y As 1-y type-II QWs on GaAs and show that this approach offers optical emission and absorption at wavelengths up to ~3 µm utilising strain-balanced structures, a first for GaAs-based QWs. Experimental measurements on a prototype GaAs 0.967 Bi 0.033 /GaN 0.062 As 0.938 structure, grown via metal-organic vapour phase epitaxy, indicate good structural quality and exhibit both photoluminescence and absorption at room temperature. The measured photoluminescence peak wavelength of 1.72 μm is in good agreement with theoretical calculations and is one of the longest emission wavelengths achieved on GaAs to date using a pseudomorphically grown heterostructure. These results demonstrate the significant potential of this new class of III-V heterostructure for long-wavelength applications.

GaAs1-xBix/GaNyAs1-y type-II quantum wells: novel strain-balanced heterostructures for GaAs-based near- and mid-infrared photonics

NASA Astrophysics Data System (ADS)

Broderick, Christopher A.; Jin, Shirong; Marko, Igor P.; Hild, Konstanze; Ludewig, Peter; Bushell, Zoe L.; Stolz, Wolfgang; Rorison, Judy M.; O'Reilly, Eoin P.; Volz, Kerstin; Sweeney, Stephen J.

2017-04-01

The potential to extend the emission wavelength of photonic devices further into the near- and mid-infrared via pseudomorphic growth on conventional GaAs substrates is appealing for a number of communications and sensing applications. We present a new class of GaAs-based quantum well (QW) heterostructure that exploits the unusual impact of Bi and N on the GaAs band structure to produce type-II QWs having long emission wavelengths with little or no net strain relative to GaAs, while also providing control over important laser loss processes. We theoretically and experimentally demonstrate the potential of GaAs1-xBix/GaNyAs1-y type-II QWs on GaAs and show that this approach offers optical emission and absorption at wavelengths up to ~3 µm utilising strain-balanced structures, a first for GaAs-based QWs. Experimental measurements on a prototype GaAs0.967Bi0.033/GaN0.062As0.938 structure, grown via metal-organic vapour phase epitaxy, indicate good structural quality and exhibit both photoluminescence and absorption at room temperature. The measured photoluminescence peak wavelength of 1.72 μm is in good agreement with theoretical calculations and is one of the longest emission wavelengths achieved on GaAs to date using a pseudomorphically grown heterostructure. These results demonstrate the significant potential of this new class of III-V heterostructure for long-wavelength applications.

Future impacts of distributed power generation on ambient ozone and particulate matter concentrations in the San Joaquin Valley of California.

PubMed

Vutukuru, Satish; Carreras-Sospedra, Marc; Brouwer, Jacob; Dabdub, Donald

2011-12-01

Distributed power generation-electricity generation that is produced by many small stationary power generators distributed throughout an urban air basin-has the potential to supply a significant portion of electricity in future years. As a result, distributed generation may lead to increased pollutant emissions within an urban air basin, which could adversely affect air quality. However, the use of combined heating and power with distributed generation may reduce the energy consumption for space heating and air conditioning, resulting in a net decrease of pollutant and greenhouse gas emissions. This work used a systematic approach based on land-use geographical information system data to determine the spatial and temporal distribution of distributed generation emissions in the San Joaquin Valley Air Basin of California and simulated the potential air quality impacts using state-of-the-art three-dimensional computer models. The evaluation of the potential market penetration of distributed generation focuses on the year 2023. In general, the air quality impacts of distributed generation were found to be small due to the restrictive 2007 California Air Resources Board air emission standards applied to all distributed generation units and due to the use of combined heating and power. Results suggest that if distributed generation units were allowed to emit at the current Best Available Control Technology standards (which are less restrictive than the 2007 California Air Resources Board standards), air quality impacts of distributed generation could compromise compliance with the federal 8-hr average ozone standard in the region.

Future Impacts of Distributed Power Generation on Ambient Ozone and Particulate Matter Concentrations in the San Joaquin Valley of California.

PubMed

Vutukuru, Satish; Carreras-Sospedra, Marc; Brouwer, Jacob; Dabdub, Donald

2011-12-01

Distributed power generation-electricity generation that is produced by many small stationary power generators distributed throughout an urban air basin-has the potential to supply a significant portion of electricity in future years. As a result, distributed generation may lead to increased pollutant emissions within an urban air basin, which could adversely affect air quality. However, the use of combined heating and power with distributed generation may reduce the energy consumption for space heating and air conditioning, resulting in a net decrease of pollutant and greenhouse gas emissions. This work used a systematic approach based on land-use geographical information system data to determine the spatial and temporal distribution of distributed generation emissions in the San Joaquin Valley Air Basin of California and simulated the potential air quality impacts using state-of-the-art three-dimensional computer models. The evaluation of the potential market penetration of distributed generation focuses on the year 2023. In general, the air quality impacts of distributed generation were found to be small due to the restrictive 2007 California Air Resources Board air emission standards applied to all distributed generation units and due to the use of combined heating and power. Results suggest that if distributed generation units were allowed to emit at the current Best Available Control Technology standards (which are less restrictive than the 2007 California Air Resources Board standards), air quality impacts of distributed generation could compromise compliance with the federal 8-hr average ozone standard in the region. [Box: see text].

GaAs1−xBix/GaNyAs1−y type-II quantum wells: novel strain-balanced heterostructures for GaAs-based near- and mid-infrared photonics

PubMed Central

Broderick, Christopher A.; Jin, Shirong; Marko, Igor P.; Hild, Konstanze; Ludewig, Peter; Bushell, Zoe L.; Stolz, Wolfgang; Rorison, Judy M.; O’Reilly, Eoin P.; Volz, Kerstin; Sweeney, Stephen J.

2017-01-01

The potential to extend the emission wavelength of photonic devices further into the near- and mid-infrared via pseudomorphic growth on conventional GaAs substrates is appealing for a number of communications and sensing applications. We present a new class of GaAs-based quantum well (QW) heterostructure that exploits the unusual impact of Bi and N on the GaAs band structure to produce type-II QWs having long emission wavelengths with little or no net strain relative to GaAs, while also providing control over important laser loss processes. We theoretically and experimentally demonstrate the potential of GaAs1−xBix/GaNyAs1−y type-II QWs on GaAs and show that this approach offers optical emission and absorption at wavelengths up to ~3 µm utilising strain-balanced structures, a first for GaAs-based QWs. Experimental measurements on a prototype GaAs0.967Bi0.033/GaN0.062As0.938 structure, grown via metal-organic vapour phase epitaxy, indicate good structural quality and exhibit both photoluminescence and absorption at room temperature. The measured photoluminescence peak wavelength of 1.72 μm is in good agreement with theoretical calculations and is one of the longest emission wavelengths achieved on GaAs to date using a pseudomorphically grown heterostructure. These results demonstrate the significant potential of this new class of III-V heterostructure for long-wavelength applications. PMID:28422129

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)). Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of biochar and other amendments on the physical properties and greenhouse gas emissions of an artificially degraded soil.

PubMed

Mukherjee, A; Lal, R; Zimmerman, A R

2014-07-15

Short and long-term impacts of biochar on soil properties under field conditions are poorly understood. In addition, there is a lack of field reports of the impacts of biochar on soil physical properties, gaseous emissions and C stability, particularly in comparison with other amendments. Thus, three amendments - biochar produced from oak at 650°C, humic acid (HA) and water treatment residual - (WTR) were added to a scalped silty-loam soil @ 0.5% (w/w) in triplicated plots under soybean. Over the 4-month active growing season, all amendments significantly increased soil pH, but the effect of biochar was the greatest. Biochar significantly increased soil-C by 7%, increased sub-nanopore surface area by 15% and reduced soil bulk density by 13% compared to control. However, only WTR amendment significantly increased soil nanopore surface area by 23% relative to the control. While total cumulative CH4 and CO2 emissions were not significantly affected by any amendment, cumulative N2O emission was significantly decreased in the biochar-amended soil (by 92%) compared to control over the growing period. Considering both the total gas emissions and the C removed from the atmosphere as crop growth and C added to the soil, WTR and HA resulted in net soil C losses and biochar as a soil C gain. However, all amendments reduced the global warming potential (GWP) of the soil and biochar addition even produced a net negative GWP effect. The short observation period, low application rate and high intra-treatment variation resulted in fewer significant effects of the amendments on the physicochemical properties of the soils than one might expect indicating further possible experimentation altering these variables. However, there was clear evidence of amendment-soil interaction processes affecting both soil properties and gaseous emissions, particularly for biochar, that might lead to greater changes with additional field emplacement time. Copyright © 2014 Elsevier B.V. All rights reserved.

[Synergistic emission reduction of chief air pollutants and greenhouse gases-based on scenario simulations of energy consumptions in Beijing].

PubMed

Xie, Yuan-bo; Li, Wei

2013-05-01

It is one of the common targets and important tasks for energy management and environmental control of Beijing to improve urban air quality while reducing the emissions of greenhouse gases (GHG). Here, based on the interim and long term developmental planning and energy structure of the city, three energy consumption scenarios in low, moderate and high restrictions were designed by taking the potential energy saving policies and environmental targets into account. The long-range energy alternatives planning (LEAP) model was employed to predict and evaluate reduction effects of the chief air pollutants and GHG during 2010 to 2020 under the three given scenarios. The results showed that if urban energy consumption system was optimized or adjusted by exercising energy saving and emission reduction and pollution control measures, the predicted energy uses will be reduced by 10 to 30 million tons of coal equivalents by 2020. Under the two energy scenarios with moderate and high restrictions, the anticipated emissions of SO2, NOx, PM10, PM2.5, VOC and GHG will be respectively reduced to 71 to 100.2, 159.2 to 218.7, 89.8 to 133.8, 51.4 to 96.0, 56.4 to 74.8 and 148 200 to 164 700 thousand tons. Correspondingly, when compared with the low-restriction scenario, the reducing rate will be 53% to 67% , 50% to 64% , 33% to 55% , 25% to 60% , 41% to 55% and 26% to 34% respectively. Furthermore, based on a study of synergistic emission reduction of the air pollutants and GHG, it was proposed that the adjustment and control of energy consumptions shall be intensively developed in the three sectors of industry, transportation and services. In this way the synergistic reduction of the emissions of chief air pollutants and GHG will be achieved; meanwhile the pressures of energy demands may be deliberately relieved.

Methods proposed to achieve air quality standards for mobile sources and technology surveillance.

PubMed Central

Piver, W T

1975-01-01

The methods proposed to meet the 1975 Standards of the Clean Air Act for mobile sources are alternative antiknocks, exhaust emission control devices, and alternative engine designs. Technology surveillance analysis applied to this situation is an attempt to anticipate potential public and environmental health problems from these methods, before they happen. Components of this analysis are exhaust emission characterization, environmental transport and transformation, levels of public and environmental exposure, and the influence of economics on the selection of alternative methods. The purpose of this presentation is to show trends as a result of the interaction of these different components. In no manner can these trends be interpreted explicitly as to what will really happen. Such an analysis is necessary so that public and environmental health officials have the opportunity to act on potential problems before they become manifest. PMID:50944

Can biochar serve as a toop to reduce soil GHG costs of agricultural production in the long term?

NASA Astrophysics Data System (ADS)

Kammann, Claudia; Finke, Christoph; Schröder, Matthias; Schmidt, Hans-Peter; Lima, Amanda; Teixeira, Wenceslau; Clough, Tim; Müller, Christoph

2013-04-01

With a growing world population and growing demands for bioenergy there is an urgent need to improve the greenhouse gas (GHG) emission-to-yield ratio of agricultural production. 'Young, production-fresh biochar has repeatedly been observed to reduce N2O emissions in a variety of agricultural soils, but it is unknown how long initial N2O-reducing effects will persist. Biochar-amended soils may even develop a potential for higher N2O emissions decades after Biochar application due to the formation of higher soil organic matter stocks when mineral N is applied. Unfortunately the longest-running field trials are not older than a few years, thus our ability for predictions is rather limited. To investigate the long-term effect that Biochar addition to soils may have on soil GHG emissions we conducted three different laboratory incubation studies with potential 'long-term analogs' that may offer insights: (I) N-rich Biochar-manure compost, versus pure manure-compost, or manure-compost were the same amount of untreated, fresh Biochar was added; (II) temperate soil from a 100-year old charcoal making (kiln) site in Germany compared to the original adjacent forest soil; and (III) two tropical Terra preta soils (secondary forest and cultivation) compared to their respective adjacent ferralsols. None of the studies indicated that old, "aged" Biochar in soils or substrates will increase the risk for N2O losses. The Biochar-compost (I) still had significantly reduced N2O emissions, or was the same as the control. However, its biological activity (respiration) was significantly increased (122% of ctrl). In contrast, the fresh Biochar addition significantly reduced N2O emissions to 39% of the control, accompanied by significantly reduced respiration rates (50% of ctrl.). The kiln-area soil (II), compared to the corresponding adjacent forest soil (both at 60% of their respective WHCmax), did not exhibit higher N2O emissions after N-fertilization over the course of one month. The kiln soils' NH4+ concentration, net nitrification and respiration, and also its methane consumption activity were all significantly increased but the labile organic-C content was reduced. The overall N2O+CH4 greenhouse gas balance of the kiln soil (expressed in CO2 equivalents) was significantly improved over that of the adjacent forest soil. Terra preta soils (III) did not show an increased potential for N2O formation before or after NH4NO3 application. Only the adjacent secondary-forest soil exhibited a sharp but quickly declining N2O emission peak. Here, again, the biological activity of the Terra preta soils was always greater than those of the corresponding adjacent ferralsols. We therefore conclude that, although the initial N2O-emission reducing capability of (untreated) biochar additions will not last forever, the danger of accelerated N2O formation in Biochar-amended soils will likely not be large in the long run. Moreover, the improved CO2-to-N2O emission-ratios (soil respiration, as an indicator for soil fertility) observed throughout the investigated analogs in space and time provide room for careful optimism that biochar may indeed be a suitable management tool to improve GHG-emission-to-yield ratios of agricultural production in the long run.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huo, Hong; Cai, Hao; Zhang, Qiang

We evaluated the fuel-cycle emissions of greenhouse gases (GHGs) and air pollutants (NOx, SO2, PM10, and PM2.5) of electric vehicles (EVs) in China and the United States (U.S.), two of the largest potential markets for EVs in the world. Six of the most economically developed and populated regions in China and the U.S. were selected. The results showed that EV fuel-cycle emissions depend substantially on the carbon intensity and cleanness of the electricity mix, and vary significantly across the regions studied. In those regions with a low share of coal-based electricity (e.g., California), EVs can reduce GHG and air pollutantmore » emissions (except for PM) significantly compared with conventional vehicles. However, in the Chinese regions and selected U.S. Midwestern states where coal dominates in the generation mix, EVs can reduce GHG emissions but increase the total and urban emissions of air pollutants. In 2025, EVs will offer greater reductions in GHG and air pollutant emissions because emissions from power plants will be better controlled; EVs in the Chinese regions examined, however, may still increase SO2 and PM emissions. Reductions of 60–85% in GHGs and air pollutants could be achieved were EVs charged with 80% renewable electricity or the electricity generated from the best available technologies of coal-fired power plants, which are futuristic power generation scenarios.« less

Methane production potential and emission at different water levels in the restored reed wetland of Hangzhou Bay

PubMed Central

Sheng, Xuancai; Wu, Ming; Wu, Hao; Ning, Xiao

2017-01-01

Changes in the hydrological conditions of coastal wetlands may potentially affect the role of wetlands in the methane (CH4) cycle. In this study, the CH4 production potential and emissions from restored coastal reed wetlands at different water levels were examined in eastern China at a field scale in two phenological seasons. Results showed that the total CH4 flux from reeds at various water levels were positive, indicating that they were “sources” of CH4. During the peak growing season, CH4 flux from reeds was greater than that during the spring thaw. CH4 flux from reeds in inundated conditions was greater than that in non-inundated conditions. The CH4 production potential during the peak growing season was far greater than that during the spring thaw. However, the effect of water level on wetland CH4 production potential differed among seasons. The correlations among CH4 production potential, soil properties and CH4 flux change at different water level. These results demonstrate that water level was related to CH4 production and CH4 flux. The growing season also plays a role in CH4 fluxes. Controlling the hydrological environment in restored wetlands has important implications for the maintenance of their function as carbon sinks. PMID:28968419

DOE Office of Scientific and Technical Information (OSTI.GOV)

Couth, R.; Trois, C., E-mail: troisc@ukzn.ac.za

Highlights: Black-Right-Pointing-Pointer The financial/social/institutional sustainability of waste management in Africa is analysed. Black-Right-Pointing-Pointer This note is a compendium of a study on the potential for GHG control via improved zero waste in Africa. Black-Right-Pointing-Pointer This study provides the framework for Local Authorities for realizing sustained GHG reductions. - Abstract: Greenhouse gas (GHG) emissions per person from urban waste management activities are greater in sub-Saharan African countries than in other developing countries, and are increasing as the population becomes more urbanised. Waste from urban areas across Africa is essentially dumped on the ground and there is little control over the resultingmore » gas emissions. The clean development mechanism (CDM), from the 1997 Kyoto Protocol has been the vehicle to initiate projects to control GHG emissions in Africa. However, very few of these projects have been implemented and properly registered. A much more efficient and cost effective way to control GHG emissions from waste is to stabilise the waste via composting and to use the composted material as a soil improver/organic fertiliser or as a component of growing media. Compost can be produced by open windrow or in-vessel composting plants. This paper shows that passively aerated open windrows constitute an appropriate low-cost option for African countries. However, to provide an usable compost material it is recommended that waste is processed through a materials recovery facility (MRF) before being composted. The paper demonstrates that material and biological treatment (MBT) are viable in Africa where they are funded, e.g. CDM. However, they are unlikely to be instigated unless there is a replacement to the Kyoto Protocol, which ceases for Registration in December 2012.« less

40 CFR 1045.120 - What emission-related warranty requirements apply to me?

Code of Federal Regulations, 2014 CFR

2014-07-01

... (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION MARINE ENGINES AND... purchaser that the new engine, including all parts of its emission control system, meets two conditions: (1... generous than we require. The emission-related warranty for an engine may not be shorter than any published...

40 CFR 86.1803-01 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... operator prior to procurement. Auxiliary Emission Control Device (AECD) means any element of design which... components are those components which are designed primarily for emission control, or whose failure may... of design means any control system (i.e., computer software, electronic control system, emission...

40 CFR 86.1803-01 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... prior to procurement. Auxiliary Emission Control Device (AECD) means any element of design which senses... components are those components which are designed primarily for emission control, or whose failure may... of design means any control system (i.e., computer software, electronic control system, emission...

Verification of a level-3 diesel emissions control strategy for transport refrigeration units

NASA Astrophysics Data System (ADS)

Shewalla, Umesh

Transport Refrigeration Units (TRUs) are refrigeration systems used to control the environment of temperature sensitive products while they are being transported from one place to another in trucks, trailers or shipping containers. The TRUs typically use an internal combustion engine to power the compressor of the refrigeration unit. In the United States TRUs are most commonly powered by diesel engines which vary from 9 to 40 horsepower. TRUs are capable of both heating and cooling. The TRU engines are relatively small, inexpensive and do not use emissions reduction techniques such as exhaust gas recirculation (EGR). A significant number of these engines operate in highly populated areas like distribution centers, truck stops, and other facilities which make them one of the potential causes for health risks to the people who live and work nearby. Diesel particulate matter (PM) is known for its adverse effects on both human beings and the environment. Considering these effects, regulatory bodies have imposed limitations on the PM emissions from a TRU engine. The objective of this study was to measure and analyze the regulated emissions from a TRU engine under both engine out and particulate filter system out conditions during pre-durability (when the filter system was new) and post-durability test (after the filter system was subjected to 1000 hours in-field trial). The verification program was performed by the Center for Alternative Fuel, Engines and Emissions (CAFEE) at West Virginia University (WVU). In this program, a catalyzed silicon carbide (SiC) diesel particulate filter (DPF) was evaluated and verified as a Level-3 Verified Diesel Emissions Control Strategy (VDECS) (. 85% PM reduction) under California Air Resources Board (CARB) regulations 2702 [1]. The emissions result showed that the filter system reduced diesel PM by a percentage of 96 +/- 1 over ISO 8178-C1 [2] cycle and 92 +/- 5 over EPA TRU [3] cycle, qualifying as a Level 3 VDECS. The percentage emission reduction in hydrocarbons (HC) and carbon monoxide (CO) was 76.8 +/- 4.8 and 72.2 +/- 5.2, respectively over both ISO 8178-C1 [2] and EPA TRU [3] cycles. It was also observed that there was 3.6 +/- 2.9 and 7.2 +/- 3.1 percentage reduction in oxides of nitrogen (NOx) and nitric oxide (NO), respectively with a slight increase in fuel consumption and carbon dioxide as a consequence of increased exhaust back pressure. It is required by the CARB regulations that the diesel emissions control strategy must not increase emissions of NO2 by more than 20% by mass over the baseline value. In this study, it was observed that the total increase in NO2 level was 5.6 +/- 2.6 percent, well within the limit specified by the CARB.