Evolution of trace gases and particles emitted by a chaparral fire in California

Treesearch

S. K. Akagi; J. S. Craven; J. W. Taylor; G. R. McMeeking; R. J. Yokelson; I. R. Burling; S. P. Urbanski; C. E. Wold; J. H. Seinfeld; H. Coe; M. J. Alvarado; D. R. Weise

2012-01-01

Biomass burning (BB) is a major global source of trace gases and particles. Accurately representing the production and evolution of these emissions is an important goal for atmospheric chemical transport models. We measured a suite of gases and aerosols emitted from an 81 hectare prescribed fire in chaparral fuels on the central coast of California, US on 17 November...

Atmosphere-Ocean Coupling through Trace Gases

NASA Astrophysics Data System (ADS)

Tegtmeier, S.; Atlas, E. L.; Krüger, K.; Lennartz, S. T.; Marandino, C. A.; Patra, P. K.; Quack, B.; Schlundt, C.

2017-12-01

Halogen- and sulfur-containing trace gases, as well as other volatile organic compounds (VOCs, such as isoprene) from biogeochemical marine sources are important constituents of the ocean and the atmosphere. These compounds exert wide-ranging influence on atmospheric chemical processes and climate interactions, as well as on human health in coastal regions. In their reactive form, they can affect the oxidizing capacity of the air and lead to the formation of new particles or the growth of existing ones. In this contribution, marine derived halogen-, sulfur-, and oxygen-containing compounds will be discussed. Their net flux into the atmosphere and their impact on atmospheric processes is analyzed based on observations and model simulations.

Pilot Institute on Global Change on Trace Gases and the Biosphere, 1988

NASA Technical Reports Server (NTRS)

Eddy, J. A.; Moore, B.

1998-01-01

Table of Contents: Summary; Background; General Framework for a Series of Institutes on Global Change; The 1988 Pilot Institute on Global Changes: Trace Gases and the Biosphere; Budget; List of Acronyms; and Attachments.

Method for detecting trace impurities in gases

DOEpatents

Freund, Samuel M.; Maier, II, William B.; Holland, Redus F.; Beattie, Willard H.

1981-01-01

A technique for considerably improving the sensitivity and specificity of infrared spectrometry as applied to quantitative determination of trace impurities in various carrier or solvent gases is presented. A gas to be examined for impurities is liquefied and infrared absorption spectra of the liquid are obtained. Spectral simplification and number densities of impurities in the optical path are substantially higher than are obtainable in similar gas-phase analyses. Carbon dioxide impurity (.about.2 ppm) present in commercial Xe and ppm levels of Freon 12 and vinyl chloride added to liquefied air are used to illustrate the method.

Method for detecting trace impurities in gases

DOEpatents

Freund, S.M.; Maier, W.B. II; Holland, R.F.; Beattie, W.H.

A technique for considerably improving the sensitivity and specificity of infrared spectrometry as applied to quantitative determination of trace impurities in various carrier or solvent gases is presented. A gas to be examined for impurities is liquefied and infrared absorption spectra of the liquid are obtained. Spectral simplification and number densities of impurities in the optical path are substantially higher than are obtainable in similar gas-phase analyses. Carbon dioxide impurity (approx. 2 ppM) present in commercial Xe and ppM levels of Freon 12 and vinyl chloride added to liquefied air are used to illustrate the method.

Greenhouse effect of chlorofluorocarbons and other trace gases

NASA Technical Reports Server (NTRS)

Hansen, James; Lacis, Andrew; Prather, Michael

1989-01-01

A comparison is made of the radiative (greenhouse) forcing of the climate system due to changes of atmospheric chlorofluorocarbons and other trace gases. It is found that CFCs, defined to include chlorofluorocarbons, chlorocarbons, and fluorocarbons, now provide about one-quater of current annual increases in anthropogenic greenhouse climate forcing. If the growth rates of CFC production in the early 1970s had continued to the present, current annual growth of climate forcing due to CFCs would exceed that due to CO2.

Epiphytic cryptogams as a source of bioaerosols and trace gases

NASA Astrophysics Data System (ADS)

Ruckteschler, Nina; Hrabe de Angelis, Isabella; Zartman, Charles E.; Araùjo, Alessandro; Pöschl, Ulrich; Manzi, Antonio O.; Andreae, Meinrat O.; Pöhlker, Christopher; Weber, Bettina

2016-04-01

Cryptogamic covers comprise (cyano-)bacteria, algae, lichens, bryophytes, fungi, and archaea in varying proportions. These organisms do not form flowers, but reproduce by spores or cell cleavage with these reproductive units being dispersed via the atmosphere. As so-called poikilohydric organisms they are unable to regulate their water content, and their physiological activity pattern mainly follows the external water conditions. We hypothesize, that both spore dispersal and the release of trace gases are governed by the moisture patterns of these organisms and thus they could have a greater impact on the atmosphere than previously thought. In order to test this hypothesis, we initiated experiments at the study site Amazonian Tall Tower Observatory (ATTO) in September 2014. We installed microclimate sensors in epiphytic cryptogams at four different heights of a tree to monitor the activity patterns of these organisms. Self-developed moisture probes are used to analyze the water status of the organisms accompanied by light and temperature sensors. The continuously logged data are linked to ongoing measurements of trace gases and particulate bioaerosols to analyze these for the relevance of cryptogams. Here, we are particularly interested in diurnal cycles of coarse mode particles and the atmospheric abundance of fine potassium-rich particles from a currently unknown biogenic source. Based upon the results of this field study we also investigate the bioaerosol and trace gas release patterns of cryptogamic covers under controlled conditions. With this combined approach of field and laboratory experiments we aim to disclose the role of cryptogamic covers in bioaerosol and trace gas release patterns in the Amazonian rainforest.

Climate-chemical interactions and effects of changing atmospheric trace gases

NASA Technical Reports Server (NTRS)

Ramanathan, V.; Callis, L.; Cess, R.; Hansen, J.; Isaksen, I.

1987-01-01

The paper considers trace gas-climate effects including the greenhouse effect of polyatomic trace gases, the nature of the radiative-chemical interactions, and radiative-dynamical interactions in the stratosphere, and the role of these effects in governing stratospheric climate change. Special consideration is given to recent developments in the investigations of the role of oceans in governing the transient climate responses, and a time-dependent estimate of the potential trace gas warming from the preindustrial era to the early 21st century. The importance of interacting modeling and observational efforts is emphasized. One of the problems remaining on the observational front is the lack of certainty in current estimates of the rate of growth of CO, O3, and NOx; the primary challenge is the design of a strategy that will minimize the sampling errors.

Monitoring shipping emissions with MAX-DOAS measurements of reactive trace gases

NASA Astrophysics Data System (ADS)

Wittrock, Folkard; Peters, Enno; Seyler, André; Kattner, Lisa; Mathieu-Üffing, Barbara; Burrows, John P.; Chirkov, Maksym; Meier, Andreas C.; Richter, Andreas; Schönhardt, Anja; Schmolke, Stefan; Theobald, Norbert

2014-05-01

Air pollution from ships contributes to overall air quality problems and it has direct health effects on the population in particular in coastal regions, and in harbor cities. In order to reduce the emissions the International Maritime Organisation (IMO) have tightened the regulations for air pollution. E.g. Sulfur Emission Control Areas (SECA) have been introduced where the sulfur content of marine fuel is limited. However, up to now there is no regular monitoring system available to verify that ships are complying with the new regulations. Furthermore measurements of reactive trace gases in marine environments are in general sparse. The project MeSMarT (Measurements of shipping emissions in the marine troposphere, www.mesmart.de) has been established as a cooperation between the University of Bremen and the German Bundesamt für Seeschifffahrt und Hydrographie (Federal Maritime and Hydrographic Agency) with support of the Helmholtz Research Centre Geesthacht to estimate the influence of ship emissions on the chemistry of the atmospheric boundary layer and to establish a monitoring system for main shipping routes. Here we present MAX-DOAS observations of NO2 and SO2 carried out during ship campaigns in the North and Baltic Sea and from two permanent sites close to the Elbe river (Wedel, Germany) and on the island Neuwerk close to the mouths of Elbe and Weser river. Mixing ratios of both trace gases have been retrieved using different approaches (pure geometric and taking into account the radiative transfer) and compared to in situ and air borne observations (see Kattner et al., Monitoring shipping emissions with in-situ measurements of trace gases, and Meier et al., Airborne measurements of NO2 shipping emissions using imaging DOAS) observations. Furthermore simple approaches have been used to calculate emission factors of NOx and SO2 for single ships.

A measurement system for the atmospheric trace gases CH4 and CO

NASA Technical Reports Server (NTRS)

Condon, E. P.

1977-01-01

A system for measuring ambient clean air levels of the atmospheric trace gases methane and carbon monoxide is described. The analytical method consists of a gas chromatographic technique that incorporates sample preconcentration with catalytic conversion of CO to CH4 and subsequent flame ionization detection of these gases. The system has sufficient sensitivity and repeatability to make the precise measurements required to establish concentration profiles for CO and CH4 in the planetary boundary layer. A discussion of the bottle sampling program being conducted to obtain the samples for the concentration profiles is also presented.

Survey of Instrumentation for the Measurement of Stratospheric Trace Gases and Particulates (CIAP)

DOT National Transportation Integrated Search

1971-11-01

A survey was conducted to determine the applicability of presently available instrumentation to the direct and/or remote measure of trace gases and particulates within the stratosphere. Consideration was also given to techniques under development whe...

Quantifying sources and sinks of trace gases using space-borne measurements: current and future science.

PubMed

Palmer, Paul I

2008-12-28

We have been observing the Earth's upper atmosphere from space for several decades, but only over the past decade has the necessary technology begun to match our desire to observe surface air pollutants and climate-relevant trace gases in the lower troposphere, where we live and breathe. A new generation of Earth-observing satellites, capable of probing the lower troposphere, are already orbiting hundreds of kilometres above the Earth's surface with several more ready for launch or in the planning stages. Consequently, this is one of the most exciting times for the Earth system scientists who study the countless current-day physical, chemical and biological interactions between the Earth's land, ocean and atmosphere. First, I briefly review the theory behind measuring the atmosphere from space, and how these data can be used to infer surface sources and sinks of trace gases. I then present some of the science highlights associated with these data and how they can be used to improve fundamental understanding of the Earth's climate system. I conclude the paper by discussing the future role of satellite measurements of tropospheric trace gases in mitigating surface air pollution and carbon trading.

Mid-Infrared OPO for High Resolution Measurements of Trace Gases in the Mars Atmosphere

NASA Technical Reports Server (NTRS)

Yu, Anthony W.; Numata,Kenji; Riris, haris; Abshire, James B.; Allan, Graham; Sun, Xiaoli; Krainak, Michael A.

2008-01-01

The Martian atmosphere is composed primarily (>95%) of CO2 and N2 gas, with CO, O2, CH4, and inert gases such as argon comprising most of the remainder. It is surprisingly dynamic with various processes driving changes in the distribution of CO2, dust, haze, clouds and water vapor on global scales in the meteorology of Mars atmosphere [I]. The trace gases and isotopic ratios in the atmosphere offer important but subtle clues as to the origins of the planet's atmosphere, hydrology, geology, and potential for biology. In the search for life on Mars, an important process is the ability of bacteria to metabolize inorganic substrates (H2, CO2 and rock) to derive energy and produce methane as a by-product of anaerobic metabolism. Trace gases have been measured in the Mars atmosphere from Earth, Mars orbit, and from the Mars surface. The concentration of water vapor and various carbon-based trace gases are observed in variable concentrations. Within the past decade multiple groups have reported detection of CH4, with concentrations in the 10's of ppb, using spectroscopic observations from Earth [2]. Passive spectrometers in the mid-infrared (MIR) are restricted to the sunlit side of the planet, generally in the mid latitudes, and have limited spectral and spatial resolution. To accurately map the global distribution and to locate areas of possibly higher concentrations of these gases such as plumes or vents requires an instrument with high sensitivity and fine spatial resolution that also has global coverage and can measure during both day and night. Our development goal is a new MIR lidar capable of measuring, on global scales, with sensitivity, resolution and precision needed to characterize the trace gases and isotopic ratios of the Martian atmosphere. An optical parametric oscillator operating in the MIR is well suited for this instrument. The sufficient wavelength tuning range of the OPO can extend the measurements to other organic molecules, CO2, atmospheric water

Improved aqueous scrubber for collection of soluble atmospheric trace gases

NASA Technical Reports Server (NTRS)

Cofer, W. R., III; Talbot, R. W.; Collins, V. G.

1985-01-01

A new concentration technique for the extraction and enrichment of water-soluble atmospheric trace gases has been developed. The gas scrubbing technique efficiently extracts soluble gases from a large volume flow rate of air sample into a small volume of refluxed trapping solution. The gas scrubber utilizes a small nebulizing nozzle that mixes the incoming air with an aqueous extracting solution to form an air/droplet mist. The mist provides excellent interfacial surface areas for mass transfer. The resulting mist sprays upward through the reaction chamber until it impinges upon a hydrophobic membrane that virtually blocks the passage of droplets but offers little resistance to the existing gas flow. Droplets containing the scrubbed gases coalesce on the membrane and drip back into the reservoir for further refluxing. After a suitable concentration period, the extracting solution containing the analyte can be withdrawn for analysis. The nebulization-reflex concentration technique is more efficient (maximum flow of gas through the minimum volume of extractant) than conventional bubbler/impinger gas extraction techniques and is offered as an alternative method.

Method for removing acid gases from a gaseous stream

DOEpatents

Gorin, Everett; Zielke, Clyde W.

1981-01-01

In a process for hydrocracking a heavy aromatic polynuclear carbonaceous feedstock containing reactive alkaline constituents to produce liquid hydrocarbon fuels boiling below about 475.degree. C. at atmospheric pressure by contacting the feedstock with hydrogen in the presence of a molten metal halide catalyst, thereafter separating a gaseous stream containing hydrogen, at least a portion of the hydrocarbon fuels and acid gases from the molten metal halide and regenerating the molten metal halide, thereby producing a purified molten metal halide stream for recycle to the hydrocracking zone, an improvement comprising; contacting the gaseous acid gas, hydrogen and hydrocarbon fuels-containing stream with the feedstock containing reactive alkaline constituents to remove acid gases from the acid gas containing stream. Optionally at least a portion of the hydrocarbon fuels are separated from gaseous stream containing hydrogen, hydrocarbon fuels and acid gases prior to contacting the gaseous stream with the feedstock.

Sensitivity of RF-driven Plasma Filaments to Trace Gases

NASA Astrophysics Data System (ADS)

Burin, M. J.; Czarnocki, C. J.; Czarnocki, K.; Zweben, S. J.; Zwicker, A.

2011-10-01

Filamentary structures have been observed in many types of plasma discharges in both natural (e.g. lightning) and industrial systems (e.g. dielectric barrier discharges). Recent progress has been made in characterizing these structures, though various aspects of their essential physics remain unclear. A common example of this phenomenon can be found within a toy plasma globe (or plasma ball), wherein a primarily neon gas mixture near atmospheric pressure clearly and aesthetically displays filamentation. Recent work has provided the first characterization of these plasma globe filaments [Campanell et al., Physics of Plasmas 2010], where it was noticed that discharges of pure gases tend not to produce filaments. We have extended this initial work to investigate in greater detail the dependence of trace gases on filamentation within a primarily Neon discharge. Our preliminary results using a custom globe apparatus will be presented, along with some discussion of voltage dependencies. Newly supported by the NSF/DOE Partnership in Basic Plasma Science and Engineering.

Tracking Oxidation During Transport of Trace Gases in Air from the Northern to Southern Hemisphere

NASA Astrophysics Data System (ADS)

Montzka, S. A.; Moore, F. L.; Atlas, E. L.; Parrish, D. D.; Miller, B. R.; Sweeney, C.; McKain, K.; Hall, B. D.; Siso, C.; Crotwell, M.; Hintsa, E. J.; Elkins, J. W.; Blake, D. R.; Barletta, B.; Meinardi, S.; Claxton, T.; Hossaini, R.

2017-12-01

Trace gas mole fractions contain the imprint of recent influences on an air mass such as sources, transport, and oxidation. Covariations among the many gases measured from flasks during ATom and HIPPO, and from the ongoing NOAA cooperative air sampling program enable recent influences to be identified from a wide range of sources including industrial activity, biomass burning, emissions from wetlands, and uptake by terrestrial ecosystems. In this work we explore the evolution of trace gas concentrations owing to atmospheric oxidation as air masses pass through the tropics, the atmospheric region with the highest concentrations of the hydroxyl radical. Variations in C2-C5 hydrocarbon concentrations downwind of source regions provide a measure of photochemical ageing in an air mass since emission, but they become less useful when tracking photochemical ageing as air is transported from the NH into the SH owing to their low mixing ratios, lifetimes that are very short relative to transport times, non-industrial sources in the tropics (e.g., biomass burning), and southern hemispheric sources. Instead, we consider a range of trace gases and trace gas pairs that provide a measure of photochemical processing as air transits the tropics. To be useful in this analysis, these trace gases would have lifetimes comparable to interhemispheric transport times, emissions arising from only the NH at constant relative magnitudes, and concentrations sufficient to allow precise and accurate measurements in both hemispheres. Some anthropogenically-emitted chlorinated hydrocarbons meet these requirements and have been measured during ATom, HIPPO, and from NOAA's ongoing surface sampling efforts. Consideration of these results and their implications for tracking photochemical processing in air as it is transported across the tropics will be presented.

Low to middle tropospheric profiles and biosphere/troposphere fluxes of acidic gases in the summertime Canadian taiga

NASA Technical Reports Server (NTRS)

Klemm, O.; Talbot, R. W.; Fitzgerald, D. R.; Klemm, K. I.; Lefer, B. L.

1994-01-01

We report features of acidic gases in the troposphere from 9 to 5000 m altitude above ground over the Canadian taiga in the summer of 1990. The measurements were conducted at a 30-m meteorological tower and from the NASA Wallops Electra aircraft as part of the joint U.S.-Canadian Arctic Boundary Layer Expedition (ABLE) 3B Northern Wetland Studies (NOWES). We sampled air for acidic gases using the mist chamber collector coupled with subsequent analysis using ion chromatography. At the tower we collected samples at two heights during a 13-day period, including diurnal studies. Using eddy flux and profile data, we estimated the biosphere/troposphere fluxes of nitric, formic, and acetic acids and sulfur dioxide. For the organic acids, emissions from the taiga in the afternoon hours and deposition during the predawn morning hours were observed. The flux intensities alone were however not high enough to explain the observed changes in mixing ratios. The measured deposition fluxes of nitric acid were high enough to have a significant influence on its mixing ratio in the boundary layer. On three days we measured vertical profiles of nitric, formic, and acetic acids through the lower to midtroposphere. We found that the chemical composition of the troposphere was extremely heterogenous. Pronounced layers of polluted air were readily apparent from our measurements. Local photochemical production and episodic long-range transport of trace components, originating from biomass burning and possibly industrial emissions, appear to have a strong influence on the composition of the troposphere and biosphere/troposphere fluxes of acidic gases at this site.

CO2 lidar for measurements of trace gases and wind velocities

NASA Technical Reports Server (NTRS)

Hess, R. V.

1982-01-01

CO2 lidar systems technology and signal processing requirements relevant to measurement needs and sensitivity are discussed. Doppler processing is similar to microwave radar, with signal reception controlled by a computer capable of both direct and heterodyne operations. Trace gas concentrations have been obtained with the NASA DIAL system, and trace gas transport has been determined with Doppler lidar measurements for wind velocity and turbulence. High vertical resolution measurement of trace gases, wind velocity, and turbulence are most important in the planetary boundary layer and in regions between the PBL and the lower stratosphere. Shear measurements are critical for airport operational safety. A sensitivity analysis for heterodyne detection with the DIAL system and for short pulses using a Doppler lidar system is presented. The development of transient injection locking techniques, as well as frequency stability by reducing chirp and catalytic control of closed cycle CO2 laser chemistry, is described.

Opo lidar sounding of trace atmospheric gases in the 3 - 4 μm spectral range

NASA Astrophysics Data System (ADS)

Romanovskii, Oleg A.; Sadovnikov, Sergey A.; Kharchenko, Olga V.; Yakovlev, Semen V.

2018-04-01

The applicability of a KTA crystal-based laser system with optical parametric oscillators (OPO) generation to lidar sounding of the atmosphere in the spectral range 3-4 μm is studied in this work. A technique developed for lidar sounding of trace atmospheric gases (TAG) is based on differential absorption lidar (DIAL) method and differential optical absorption spectroscopy (DOAS). The DIAL-DOAS technique is tested to estimate its efficiency for lidar sounding of atmospheric trace gases. The numerical simulation performed shows that a KTA-based OPO laser is a promising source of radiation for remote DIAL-DOAS sounding of the TAGs under study along surface tropospheric paths. A possibility of using a PD38-03-PR photodiode for the DIAL gas analysis of the atmosphere is shown.

The effects of biomass burning on the concentration of trace gases in the atmosphere

NASA Technical Reports Server (NTRS)

Donaldson, Leon M.

1988-01-01

Over the past several years, there has been considerable interest concerning the global effects of biomass burning on concentrations of trace gases in the atmosphere. The paucity of reported studies and investigations into the effects of the Greenhouse Gases such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), up until about a decade ago, would suggest that the topic was not then one of universal concern. Efforts are now being made to understand the biogenic, anthropogenic and photochemical sources of atmospheric trace gases. Biomass burning which includes the burning of forests for clearing, the burning of vegetative stubble after harvesting, and lightning and human-induced wildfires is but one consideration under the general paradigm of atmospheric perturbations. A team of researchers from the Langley Research Center, along with the Canadian Forest Ministry, Ontario, Canada collaborated in an experiment in a deforestration effort through a prescribed burn. Through a specially designed experimental modeling and instrumentation, a substantial pre-burn data set was collected. The primary focus of the pre-burn experimental activities was the emission of nitrous oxide (N2O) gas from selected sites.

Parallel-plate wet denuder coupled ion chromatograph for near-real-time detection of trace acidic gases in clean room air.

PubMed

Takeuchi, Masaki; Tsunoda, Hiromichi; Tanaka, Hideji; Shiramizu, Yoshimi

2011-01-01

This paper describes the performance of our automated acidic (CH(3)COOH, HCOOH, HCl, HNO(2), SO(2), and HNO(3)) gases monitor utilizing a parallel-plate wet denuder (PPWD). The PPWD quantitatively collects gaseous contaminants at a high sample flow rate (∼8 dm(3) min(-1)) compared to the conventional methods used in a clean room. Rapid response to any variability in the sample concentration enables near-real-time monitoring. In the developed monitor, the analyte collected with the PPWD is pumped into one of two preconcentration columns for 15 min, and determined by means of ion chromatography. While one preconcentration column is used for chromatographic separation, the other is used for loading the sample solution. The system allows continuous monitoring of the common acidic gases in an advanced semiconductor manufacturing clean room. 2011 © The Japan Society for Analytical Chemistry

Mobile Platforms for Continuous Spatial Measurements of Urban Trace Gases and Criteria Pollutants

NASA Astrophysics Data System (ADS)

Fasoli, B.; Mitchell, L.; Bares, R.; Crosman, E.; Bush, S. E.; Horel, J.; Lin, J. C.; Bowling, D. R.; Ehleringer, J. R.

2015-12-01

Surface-based observations of atmospheric trace gases and criteria pollutants provide critical data on how emissions and pollutant concentrations vary over time. However, traditional stationary measurement sites only quantify concentrations at a single point in space, limiting our ability to understand spatial patterns. Using trace gas instrumentation capable of making continuous high-frequency (~1s) measurements, we have developed mobile platforms to complement stationary observation sites in order to better constrain the heterogeneity and complexities of urban emissions. These compact trace gas and criteria pollutant measurement systems are capable of precisely measuring CO2, CH4 PM2.5, O3, NOx, and several meteorological parameters on TRAX, Salt Lake City's light-rail system, and in a van-based mobile laboratory. Using case study observations, we discuss mobile measurement methodologies and the practical applications of mobile trace gas sampling platforms.

Greenhouse Trace Gases in Deadwood

NASA Astrophysics Data System (ADS)

Covey, Kristofer; Bueno de Mesquita, Cliff; Oberle, Brad; Maynard, Dan; Bettigole, Charles; Crowther, Thomas; Duguid, Marlyse; Steven, Blaire; Zanne, Amy; Lapin, Marc; Ashton, Mark; Oliver, Chad; Lee, Xuhui; Bradford, Mark

2016-04-01

Deadwood, long recognized as playing an important role in carbon cycling in forest ecosystems, is more recently drawing attention for its potential role in the cycling of other greenhouse trace gases. We report data from four independent studies measuring internal gas concentrations in deadwood in in three Quercus dominated upland forest systems in the Northeastern and Central United States. Mean methane concentrations in deadwood were 23 times atmospheric levels, indicating a lower bound, mean radial wood surface area flux of ~6 x 10-4 μmol CH4 m-2 s-1. Site, decay class, diameter, and species were all highly significant predictors of methane abundance in deadwood, and log diameter and decay stage interacted as important controls limiting methane concentrations in the smallest and most decayed logs. Nitrous oxide concentrations were negatively correlated with methane and on average ~25% lower than ambient, indicating net consumption of nitrous oxide. These data suggest nonstructural carbohydrates fuel archaeal methanogens and confirm the potential for widespread in situ methanogenesis in both living and deadwood. Applying this understanding to estimate methane emissions from microbial activity in living trees implies a potential global flux of 65.6±12.0 Tg CH4 yr-1, more than 20 times greater than currently considered.

Column amounts of trace gases from ground based FTIR measurements in the late north polar winters 1990 and 1991

NASA Technical Reports Server (NTRS)

Adrian, Gabriele; Blumenstock, Thomas; Fischer, Herbert; Frank, Eckard; Gerhardt, Lothar; Gulde, Thomas; Maucher, Guido; Oelhaf, Hermann; Thomas, Peter; Trieschmann, Olaf

1994-01-01

Two FTIR spectrometers were employed in the late winters 1990 and 1991 in Esrange, North Sweden, and in Ny Aalesund, Spitsbergen to detect zenith column amounts of several trace gases. Time series of column amounts of the trace gases O3, N2O, CH4, HNO3, NO2, CHl, and HF have been derived from the measured spectra. Additionally, some information on the vertical distribution of HCl could be obtained by analyzing the spectral line shapes. The results are interpreted in terms of dynamical and chemical processes.

NATIONAL- AND STATE-LEVEL EMISSIONS ESTIMATES OF RADIATIVELY IMPORTANT TRACE GASES (RITGS) FROM ANTHROPOGENIC SOURCES

EPA Science Inventory

The report documents the development of national- and state- level emissions estimates of radiatively important trace gases (RlTGs). Emissions estimates are presented for the principal anthropogenic sources of carbon dioxide (CO2), methane (CH4), chlorofluorocarbons (CFCs), and o...

The temporal and spatial variability of halogenated trace gases in the upper troposphere.

NASA Astrophysics Data System (ADS)

Oram, D.; O'Sullivan, D.; Brenninkmeijer, C.; van Velthoven, P.; Sturges, W.

2007-12-01

Halogenated trace gases play an important role in stratospheric and tropospheric chemistry, particularly affecting ozone concentrations. In addition they have direct and indirect effects on radiative forcing, and impact on tropospheric reactivity. Data from the CARIBIC project (Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrumented Container) have been used in conjunction with back-trajectory analysis to further our understanding of the chemical composition, inter-hemispheric distribution and source regions of halogenated compounds in the upper troposphere and lower stratosphere. Whole air samples collected within CARIBIC, have been analyzed using gas chromatography mass spectrometry for around 35 halocarbons and related trace gases, among them many potent greenhouse gases and species important for ozone depletion. The large spatial and temporal coverage of the CARIBIC project has enabled new work to be done investigating recent inter-annual trends in the CFCs, halons, and other anthropogenic halocarbons, as well as identifying clear inter-hemispheric and seasonal variability for a number of species, such as methylene chloride, HCFCs, methyl chloride, methyl bromide, methyl iodide and several reactive short lived bromo and chloro carbons. In this paper results from the CARIBIC flights to China and the Philippines will be highlighted, to discuss anthropogenic emissions of ozone depleting and greenhouse gases, from Asia and Africa. Data from flights to South America will also be presented. As production and consumption of many of these substances are being phased out in Europe and North America, emissions from Asia, Africa and also South America are becoming increasingly more important. Emissions from these regions are also of interest, as the most significant sources are often collocated with regions of convection in the tropics and sub-tropics. Thus enabling a greater proportion of the substances emitted to reach the stratosphere, where

Analysis of Process Gases and Trace Contaminants in Membrane-Aerated Gaseous Effluent Streams.

NASA Technical Reports Server (NTRS)

Coutts, Janelle L.; Lunn, Griffin Michael; Meyer, Caitlin E.

2015-01-01

In membrane-aerated biofilm reactors (MABRs), hollow fibers are used to supply oxygen to the biofilms and bulk fluid. A pressure and concentration gradient between the inner volume of the fibers and the reactor reservoir drives oxygen mass transport across the fibers toward the bulk solution, providing the fiber-adhered biofilm with oxygen. Conversely, bacterial metabolic gases from the bulk liquid, as well as from the biofilm, move opposite to the flow of oxygen, entering the hollow fiber and out of the reactor. Metabolic gases are excellent indicators of biofilm vitality, and can aid in microbial identification. Certain gases can be indicative of system perturbations and control anomalies, or potentially unwanted biological processes occurring within the reactor. In confined environments, such as those found during spaceflight, it is important to understand what compounds are being stripped from the reactor and potentially released into the crew cabin to determine the appropriateness or the requirement for additional mitigation factors. Reactor effluent gas analysis focused on samples provided from Kennedy Space Center's sub-scale MABRs, as well as Johnson Space Center's full-scale MABRs, using infrared spectroscopy and gas chromatography techniques. Process gases, such as carbon dioxide, oxygen, nitrogen, nitrogen dioxide, and nitrous oxide, were quantified to monitor reactor operations. Solid Phase Microextraction (SPME) GC-MS analysis was used to identify trace volatile compounds. Compounds of interest were subsequently quantified. Reactor supply air was examined to establish target compound baseline concentrations. Concentration levels were compared to average ISS concentration values and/or Spacecraft Maximum Allowable Concentration (SMAC) levels where appropriate. Based on a review of to-date results, current trace contaminant control systems (TCCS) currently on board the ISS should be able to handle the added load from bioreactor systems without the need

A fiber optic sensor with a metal organic framework as a sensing material for trace levels of water in industrial gases.

PubMed

Ohira, Shin-Ichi; Miki, Yusuke; Matsuzaki, Toru; Nakamura, Nao; Sato, Yu-ki; Hirose, Yasuo; Toda, Kei

2015-07-30

Industrial gases such as nitrogen, oxygen, argon, and helium are easily contaminated with water during production, transfer and use, because there is a high volume fraction of water in the atmosphere (approximately 1.2% estimated with the average annual atmospheric temperature and relative humidity). Even trace water (<1 parts per million by volume (ppmv) of H2O, dew point < -76 °C) in the industrial gases can cause quality problems in the process such as production of semiconductors. Therefore, it is important to monitor and to control trace water levels in industrial gases at each supplying step, and especially during their use. In the present study, a fiber optic gas sensor was investigated for monitoring trace water levels in industrial gases. The sensor consists of a film containing a metal organic framework (MOF). MOFs are made of metals coordinated to organic ligands, and have mesoscale pores that adsorb gas molecules. When the MOF, copper benzene-1,3,5-tricarboxylate (Cu-BTC), was used as a sensing material, we investigated the color of Cu-BTC with water adsorption changed both in depth and tone. Cu-BTC crystals appeared deep blue in dry gases, and then changed to light blue in wet gases. An optical gas sensor with the Cu-BTC film was developed using a light emitting diode as the light source and a photodiode as the light intensity detector. The sensor showed a reversible response to trace water, did not require heating to remove the adsorbed water molecules. The sample gas flow rate did not affect the sensitivity. The obtained limit of detection was 40 parts per billion by volume (ppbv). The response time for sample gas containing 2.5 ppmvH2O was 23 s. The standard deviation obtained for daily analysis of 1.0 ppmvH2O standard gas over 20 days was 9%. Furthermore, the type of industrial gas did not affect the sensitivity. These properties mean the sensor will be applicable to trace water detection in various industrial gases. Copyright © 2015 Elsevier B

Global emissions of trace gases, particulate matter, and hazardous air pollutants from open burning of domestic waste.

PubMed

Wiedinmyer, Christine; Yokelson, Robert J; Gullett, Brian K

2014-08-19

The open burning of waste, whether at individual residences, businesses, or dump sites, is a large source of air pollutants. These emissions, however, are not included in many current emission inventories used for chemistry and climate modeling applications. This paper presents the first comprehensive and consistent estimates of the global emissions of greenhouse gases, particulate matter, reactive trace gases, and toxic compounds from open waste burning. Global emissions of CO2 from open waste burning are relatively small compared to total anthropogenic CO2; however, regional CO2 emissions, particularly in many developing countries in Asia and Africa, are substantial. Further, emissions of reactive trace gases and particulate matter from open waste burning are more significant on regional scales. For example, the emissions of PM10 from open domestic waste burning in China is equivalent to 22% of China's total reported anthropogenic PM10 emissions. The results of the emissions model presented here suggest that emissions of many air pollutants are significantly underestimated in current inventories because open waste burning is not included, consistent with studies that compare model results with available observations.

Climate-chemical interactions and greenhouse effects of trace gases

NASA Technical Reports Server (NTRS)

Shi, Guang-Yu; Fan, Xiao-Biao

1994-01-01

A completely coupled one-dimensional radiative-convective (RC) and photochemical-diffusion (PC) model has been developed recently and used to study the climate-chemical interactions. The importance of radiative-chemical interactions within the troposphere and stratosphere has been examined in some detail. We find that increases of radiatively and/or chemically active trace gases such as CO2, CH4 and N2O have both the direct effects and the indirect effects on climate change by changing the atmospheric O3 profile through their interaction with chemical processes in the atmosphere. It is also found that the climatic effect of ozone depends strongly on its vertical distribution throughout the troposphere and stratosphere, as well on its column amount in the atmosphere.

Potential for the use of reconstructed IASI radiances in the detection of atmospheric trace gases

NASA Astrophysics Data System (ADS)

Atkinson, N. C.; Hilton, F. I.; Illingworth, S. M.; Eyre, J. R.; Hultberg, T.

2010-02-01

Principal component (PC) analysis has received considerable attention as a technique for the extraction of meteorological signals from hyperspectral infra-red sounders such as the Infrared Atmospheric Sounding Interferometer (IASI) and the Atmospheric Infrared Sounder (AIRS). In addition to achieving substantial bit-volume reductions for dissemination purposes, the technique can also be used to generate reconstructed radiances in which random instrument noise has been suppressed. To date, most studies have been in the context of Numerical Weather Prediction (NWP). This study examines the potential of PC analysis for chemistry applications. A major concern in the use of PC analysis for chemistry has been that the spectral features associated with trace gases may not be well represented in the reconstructed spectra, either due to deficiencies in the training set or due to the limited number of PC scores used in the radiance reconstruction. In this paper we show examples of reconstructed IASI radiances for several trace gases: ammonia, sulphur dioxide, methane and carbon monoxide. It is shown that care must be taken in the selection of spectra for the initial training set: an iterative technique, in which outlier spectra are added to a base training set, gives the best results. For the four trace gases examined, the chemical signatures are retained in the reconstructed radiances, whilst achieving a substantial reduction in instrument noise. A new regional re-transmission service for IASI is scheduled to start in 2010, as part of the EUMETSAT Advanced Retransmission Service (EARS). For this EARS-IASI service it is intended to include PC scores as part of the data stream. The paper describes the generation of the reference eigenvectors for this new service.

High sensitivity detection of trace gases at atmospheric pressure using tunable diode lasers

NASA Technical Reports Server (NTRS)

Reid, J.; Sinclair, R. L.; Grant, W. B.; Menzies, R. T.

1985-01-01

A detailed study of the detection of trace gases at atmospheric pressure using tunable diode lasers is described. The influence of multipass cells, retroreflectors and topographical targets is examined. The minimum detectable infrared absorption ranges from 0.1 percent for a pathlength of 1.2 km to 0.01 percent over short pathlengths. The factors which limit this sensitivity are discussed, and the techniques are illustrated by monitoring atmospehric CO2 and CH4.

Potential for the use of reconstructed IASI radiances in the detection of atmospheric trace gases

NASA Astrophysics Data System (ADS)

Atkinson, N. C.; Hilton, F. I.; Illingworth, S. M.; Eyre, J. R.; Hultberg, T.

2010-07-01

Principal component (PC) analysis has received considerable attention as a technique for the extraction of meteorological signals from hyperspectral infra-red sounders such as the Infrared Atmospheric Sounding Interferometer (IASI) and the Atmospheric Infrared Sounder (AIRS). In addition to achieving substantial bit-volume reductions for dissemination purposes, the technique can also be used to generate reconstructed radiances in which random instrument noise has been reduced. Studies on PC analysis of hyperspectral infrared sounder data have been undertaken in the context of numerical weather prediction, instrument monitoring and geophysical variable retrieval, as well as data compression. This study examines the potential of PC analysis for chemistry applications. A major concern in the use of PC analysis for chemistry is that the spectral features associated with trace gases may not be well represented in the reconstructed spectra, either due to deficiencies in the training set or due to the limited number of PC scores used in the radiance reconstruction. In this paper we show examples of reconstructed IASI radiances for several trace gases: ammonia, sulphur dioxide, methane and carbon monoxide. It is shown that care must be taken in the selection of spectra for the initial training set: an iterative technique, in which outlier spectra are added to a base training set, gives the best results. For the four trace gases examined, key features of the chemical signatures are retained in the reconstructed radiances, whilst achieving a substantial reduction in instrument noise. A new regional re-transmission service for IASI is scheduled to start in 2010, as part of the EUMETSAT Advanced Retransmission Service (EARS). For this EARS-IASI service it is intended to include PC scores as part of the data stream. The paper describes the generation of the reference eigenvectors for this new service.

What can surface measurements of long-lived trace gases tell us about interannual variability in UTLS transport?

NASA Astrophysics Data System (ADS)

Ray, E. A.; Daniel, J. S.; Montzka, S. A.; Portmann, R. W.; Yu, P.; Rosenlof, K. H.; Moore, F. L.

2017-12-01

We use surface measurements of a number of long-lived trace gases, including CFC-11, CFC-12 and N2O, and a 3-box model to estimate the interannual variability of bulk stratospheric transport characteristics. Coherent features among the different surface measurements suggest that there have been periods over the last two decades with significant variability in the amount of stratospheric loss transported downward to the troposphere both globally and between the NH and SH. This is especially apparent around the year 2000 and in the recent period since 2013 when surface measurements suggest an overall slowdown of the transport of stratospheric air to the troposphere as well as a shift towards a relatively stronger stratospheric circulation in the SH compared to the NH. We compare these results to stratospheric satellite measurements, residual circulation estimates and global model simulations to check for consistency. The implications of not accounting for interannual variability in stratospheric loss transported to the surface in emission estimates of long-lived trace gases can be significant, including for those gases monitored by the Montreal Protocol and/or of climatic importance.

Development of Optical Parametric Amplifier for Lidar Measurements of Trace Gases on Earth and Mars

NASA Technical Reports Server (NTRS)

Numata, Kenji; Riris, Haris; Li, Steve; Wu, Stewart; Kawa, Stephen R.; Krainak, Michael; Abshire, James

2011-01-01

Trace gases in planetary atmospheres offer important clues as to the origins of the planet's hydrology, geology. atmosphere. and potential for biology. Wc report on the development effort of a nanosecond-pulsed optical parametric amplifier (OPA) for remote trace gas measurements for Mars and Earth. The OP A output light is single frequency with high spectral purity and is widely tunable both at 1600 nm and 3300 nm with an optical-optical conversion efficiency of approximately 40%. We demonstrated open-path atmospheric measurements ofCH4 (3291 nm and 1651 nm). CO2 (1573 nm), H20 (1652 nm) with this laser source.

Measurements of Trace Gases Using a Tunable Diode Laser

NASA Technical Reports Server (NTRS)

Jost, Hans-Juerg

2005-01-01

This report is the final report for "Measurements of Trace Gases Using a Tunable Diode Laser." The tasks outlined in the proposal are listed below with a brief comment. The publications and the conference presentations are listed. Finally, the important publications are attached. The Cooperative Agreement made possible a research effort to produce high- precision and high-accuracy in-situ measurements of carbon monoxide, methane and nitrous oxide on the WB-57 during the CRYSTAL-FACE and pre-AVE field campaigns and to analyze these measurements. These measurements of CO and CH4 were of utmost importance to studies of the radiative effects of clouds. Some important results of the CRYSTAL-FACE program were contained in two scientific papers (attached). This Cooperative Agreement allowed the participation of the Argus instrument in the program and the analysis of the data.

In situ measurements and modeling of reactive trace gases in a small biomass burning plume

NASA Astrophysics Data System (ADS)

Müller, Markus; Anderson, Bruce E.; Beyersdorf, Andreas J.; Crawford, James H.; Diskin, Glenn S.; Eichler, Philipp; Fried, Alan; Keutsch, Frank N.; Mikoviny, Tomas; Thornhill, Kenneth L.; Walega, James G.; Weinheimer, Andrew J.; Yang, Melissa; Yokelson, Robert J.; Wisthaler, Armin

2016-03-01

An instrumented NASA P-3B aircraft was used for airborne sampling of trace gases in a plume that had emanated from a small forest understory fire in Georgia, USA. The plume was sampled at its origin to derive emission factors and followed ˜ 13.6 km downwind to observe chemical changes during the first hour of atmospheric aging. The P-3B payload included a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS), which measured non-methane organic gases (NMOGs) at unprecedented spatiotemporal resolution (10 m spatial/0.1 s temporal). Quantitative emission data are reported for CO2, CO, NO, NO2, HONO, NH3, and 16 NMOGs (formaldehyde, methanol, acetonitrile, propene, acetaldehyde, formic acid, acetone plus its isomer propanal, acetic acid plus its isomer glycolaldehyde, furan, isoprene plus isomeric pentadienes and cyclopentene, methyl vinyl ketone plus its isomers crotonaldehyde and methacrolein, methylglyoxal, hydroxy acetone plus its isomers methyl acetate and propionic acid, benzene, 2,3-butanedione, and 2-furfural) with molar emission ratios relative to CO larger than 1 ppbV ppmV-1. Formaldehyde, acetaldehyde, 2-furfural, and methanol dominated NMOG emissions. No NMOGs with more than 10 carbon atoms were observed at mixing ratios larger than 50 pptV ppmV-1 CO. Downwind plume chemistry was investigated using the observations and a 0-D photochemical box model simulation. The model was run on a nearly explicit chemical mechanism (MCM v3.3) and initialized with measured emission data. Ozone formation during the first hour of atmospheric aging was well captured by the model, with carbonyls (formaldehyde, acetaldehyde, 2,3-butanedione, methylglyoxal, 2-furfural) in addition to CO and CH4 being the main drivers of peroxy radical chemistry. The model also accurately reproduced the sequestration of NOx into peroxyacetyl nitrate (PAN) and the OH-initiated degradation of furan and 2-furfural at an average OH concentration of 7.45 ± 1.07 × 106 cm-3 in the

In situ measurements and modeling of reactive trace gases in a small biomass burning plume

NASA Astrophysics Data System (ADS)

Müller, M.; Anderson, B.; Beyersdorf, A.; Crawford, J. H.; Diskin, G.; Eichler, P.; Fried, A.; Keutsch, F. N.; Mikoviny, T.; Thornhill, K. L.; Walega, J. G.; Weinheimer, A. J.; Yang, M.; Yokelson, R.; Wisthaler, A.

2015-11-01

An instrumented NASA P-3B aircraft was used for airborne sampling of trace gases in a plume that had emanated from a small forest understory fire in Georgia, USA. The plume was sampled at its origin for deriving emission factors and followed ~ 13.6 km downwind for observing chemical changes during the first hour of atmospheric aging. The P-3B payload included a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS), which measured non-methane organic gases (NMOGs) at unprecedented spatio-temporal resolution (10 m/0.1 s). Quantitative emission data are reported for CO2, CO, NO, NO2, HONO, NH3 and 16 NMOGs (formaldehyde, methanol, acetonitrile, propene, acetaldehyde, formic acid, acetone plus its isomer propanal, acetic acid plus its isomer glycolaldehyde, furan, isoprene plus isomeric pentadienes and cyclopentene, methyl vinyl ketone plus its isomers crotonaldehyde and methacrolein, methylglyoxal, hydroxy acetone plus its isomers methyl acetate and propionic acid, benzene, 2,3-butandione and 2-furfural) with molar emission ratios relative to CO larger than 1 ppbV ppmV-1. Formaldehyde, acetaldehyde, 2-furfural and methanol dominated NMOG emissions. No NMOGs with more than 10 carbon atoms were observed at mixing ratios larger than 50 ppbV ppmV-1 CO emitted. Downwind plume chemistry was investigated using the observations and a 0-D photochemical box model simulation. The model was run on a near-explicit chemical mechanism (MCM v3.3) and initialized with measured emission data. Ozone formation during the first hour of atmospheric aging was well captured by the model, with carbonyls (formaldehyde, acetaldehyde, 2,3-butanedione, methylglyoxal, 2-furfural) in addition to CO and CH4 being the main drivers of peroxy radical chemistry. The model also accurately reproduced the sequestration of NOx into PAN and the OH-initiated degradation of furan and 2-furfural at an average OH concentration of 7.45 ± 1.07 × 106 cm-3 in the plume. Formaldehyde, acetone

Noble Gases Trace Earth's Subducted Water Flux

NASA Astrophysics Data System (ADS)

Smye, A.; Jackson, C.; Konrad-Schmolke, M.; Parman, S. W.; Ballentine, C. J.

2016-12-01

Volatile elements are transported from Earth's surface reservoirs back into the mantle during subduction of oceanic lithosphere [e.g. 1]. Here, we investigate the degree to which the fate of slab-bound noble gases and water are linked through the subduction process. Both water and noble gases are soluble in ring-structured minerals, such as amphibole, that are common constituents of subducted oceanic lithosphere. Heating and burial during subduction liberates noble gases and water from minerals through a combination of diffusion and dissolution. Combining a kinetic model, parameterized for noble gas fractionation in amphibole [2], with thermodynamic phase equilibria calculations, we quantify the effect of subduction dehydration on the elemental composition of slab-bound noble gases. Results show that post-arc slab water and noble gas fluxes are highly correlated. Hot subduction zones, which likely dominate over geologic history, efficiently remove noble gases and water from the down-going slab; furthermore, kinetic fractionation of noble gases is predicted to occur beneath the forearc. Conversely, hydrated portions of slab mantle in cold subduction zones transport noble gases and water to depths exceeding 200 km. Preservation of seawater-like abundances of Ar, Kr and Xe in the convecting mantle [1] implies that recycling of noble gases and water occurred during cold subduction and that the subduction efficiency of these volatile elements has increased over geological time, driven by secular cooling of the mantle. [1] Holland, G. and Ballentine, C. (2006). Nature 441, 186-191. [2] Jackson et al. (2013). Nat.Geosci. 6, 562-565.

Process for removal of ammonia and acid gases from contaminated waters

DOEpatents

King, C. Judson; MacKenzie, Patricia D.

1985-01-01

Contaminating basic gases, i.e., ammonia, and acid gases, e.g., carbon dioxide, are removed from process waters or waste waters in a combined extraction and stripping process. Ammonia in the form of ammonium ion is extracted by an immiscible organic phase comprising a liquid cation exchange component, especially an organic phosphoric acid derivative, and preferably di-2-ethyl hexyl phosphoric acid, dissolved in an alkyl hydrocarbon, aryl hydrocarbon, higher alcohol, oxygenated hydrocarbon, halogenated hydrocarbon, and mixtures thereof. Concurrently, the acidic gaseous contaminants are stripped from the process or waste waters by stripping with steam, air, nitrogen, or the like. The liquid cation exchange component has the ammonia stripped therefrom by heating, and the component may be recycled to extract additional amounts of ammonia.

Process for removal of ammonia and acid gases from contaminated waters

DOEpatents

King, C.J.; Mackenzie, P.D.

1982-09-03

Contaminating basic gases, i.e., ammonia and acid gases, e.g., carbon dioxide, are removed from process waters or waste waters in a combined extraction and stripping process. Ammonia in the form of ammonium ion is extracted by an immiscible organic phase comprising a liquid cation exchange component, especially an organic phosphoric acid derivative, and preferably di-2-ethyl hexyl phosphoric acid, dissolved in an alkyl hydrocarbon, aryl hydrocarbon, higher alcohol, oxygenated hydrocarbon, halogenated hydrocarbon, and mixtures thereof. Concurrently, the acidic gaseous contaminants are stripped from the process or waste waters by stripping with stream, air, nitrogen, or the like. The liquid cation exchange component has the ammonia stripped therefrom by heating, and the component may be recycled to extract additional amounts of ammonia.

Method and apparatus for detecting and measuring trace impurities in flowing gases

DOEpatents

Taylor, Gene W.; Dowdy, Edward J.

1979-01-01

Trace impurities in flowing gases may be detected and measured by a dynamic atomic molecular emission spectrograph utilizing as its energy source the energy transfer reactions of metastable species, atomic or molecular, with the impurities in the flowing gas. An electronically metastable species which maintains a stable afterglow is formed and mixed with the flowing gas in a region downstream from and separate from the region in which the metastable species is formed. Impurity levels are determined quantitatively by the measurement of line and/or band intensity as a function of concentration employing emission spectroscopic techniques.

Environmental factors controlling transient and seasonal changes of trace gases within shallow vadose zone

NASA Astrophysics Data System (ADS)

Pla, Concepcion; Galiana-Merino, Juan Jose; Cuezva, Soledad; Fernandez-Cortes, Angel; Garcia-Anton, Elena; Cuevas, Jaime; Cañaveras, Juan Carlos; Sanchez-Moral, Sergio; Benavente, David

2014-05-01

Shallow vadose environments below soil, mainly caves, show significant seasonal and even daily variations in gas composition of ground air, which involves the exchange of large amounts of gases, e.g. greenhouse gases (GHGs) as CO2 or CH4, with the lower troposphere. To understand better the role of caves as a sink or depot of GHGs, geochemical tracing of air (atmosphere, soil and ground air) was performed at Rull cave (southeast Spain) by monitoring CH4, CO2 and the stable carbon isotopic delta13C[CO2] using cavity ring-down spectroscopy (CRDS). A comprehensive microclimatic monitoring of exterior and cave atmosphere was simultaneously conducted to GHGs-tracking, including factors as temperature, barometric pressure, relative humidity and concentration of CO2 and 222Rn. The analysis of the measured data allows understanding outgassing and isolation processes taking place in the karst cavity. Annual patterns of gases behaviour can be distinguished, depending on the prevailing relationship between outer atmosphere, indoor atmosphere and soil system. Cave air temperature fluctuates around 15.7 ºC and relative humidity remains higher than 96% the whole annual cycle. The mean concentration of 222Rn is 1584 Bq m-3 while CO2 remains 1921 ppm. When external temperature is higher of indoor temperature (April-October), the highest levels of both trace gases are reached, while levels drop to its lowest values in the coldest months. Preliminary results obtained show an annual variation in concentration of CO2 inside the cave between 3300 ppm and 900 ppm, whereas corresponding isotopic signal delta13CO2 varies between -24‰ and -21‰. The results have been studied by Keeling model that approximates the isotopic signal of the source contribution in a resulting air mix. The values registered inside the cave were represented joined to results for exterior air (average values round 410 ppm of CO2 and -9 ‰ for delta13C). Value obtained is -27‰ pointing to a high influence of

Recent trends in the variability of halogenated trace gases over the United States

NASA Astrophysics Data System (ADS)

Hurst, Dale F.; Bakwin, Peter S.; Elkins, James W.

1998-10-01

Recent trends in the atmospheric variability of seven halogenated trace gases are determined from three years (November 1994 through October 1997) of hourly gas chromatographic measurements at a 610 m tower in North Carolina and 17 months (June 1996 through October 1997) of similar measurements at a 450 m tower in Wisconsin. Production of five of these gases, CCl3F (CFC-11), CCl2F2 (CFC-12), CCl2FCClF2 (CFC-113), CH3CCl3 (methyl chloroform), and CCl4 (carbon tetrachloride), is now strictly regulated in the United States and other developed countries under international legislation. C2Cl4 (tetrachloroethene) and SF6 (sulfur hexafluoride) are currently produced without restriction, but requests for voluntary cutbacks in C2Cl4 emissions have been made, at least in the United States. Atmospheric variability of these gases is examined at several sampling heights on the towers, but trends are deduced using only nighttime data at the top sampling level of each tower to minimize variability driven by local emissions and the diurnal cycle of the planetary boundary layer, leaving regional emissions as the main source of day-to-day variability. Significant downward trends are determined for CFC-12, CFC-113, CH3CCl3, and C2Cl4 variability at both towers, reflecting decreased emissions of these gases in two regions of the United States. Trends in CFC-11, CCl4, and SF6 variability at both towers are not significantly different from zero.

The airborne mass spectrometer AIMS - Part 2: Measurements of trace gases with stratospheric or tropospheric origin in the UTLS

NASA Astrophysics Data System (ADS)

Jurkat, Tina; Kaufmann, Stefan; Voigt, Christiane; Schäuble, Dominik; Jeßberger, Philipp; Ziereis, Helmut

2016-04-01

Understanding the role of climate-sensitive trace gas variabilities in the upper troposphere and lower stratosphere region (UTLS) and their impact on its radiative budget requires accurate measurements. The composition of the UTLS is governed by transport and chemistry of stratospheric and tropospheric constituents, such as chlorine, nitrogen oxide and sulfur compounds. The Atmospheric chemical Ionization Mass Spectrometer AIMS has been developed to accurately measure a set of these constituents on aircraft by means of chemical ionization. Here we present a setup using SF5- reagent ions for the simultaneous measurement of trace gas concentrations of HCl, HNO3 and SO2 in the pptv to ppmv (10-12 to 10-6 mol mol-1) range with in-flight and online calibration called AIMS-TG (Atmospheric chemical Ionization Mass Spectrometer for measurements of trace gases). Part 1 of this paper (Kaufmann et al., 2016) reports on the UTLS water vapor measurements with the AIMS-H2O configuration. The instrument can be flexibly switched between two configurations depending on the scientific objective of the mission. For AIMS-TG, a custom-made gas discharge ion source has been developed for generation of reagent ions that selectively react with HCl, HNO3, SO2 and HONO. HNO3 and HCl are routinely calibrated in-flight using permeation devices; SO2 is continuously calibrated during flight adding an isotopically labeled 34SO2 standard. In addition, we report on trace gas measurements of HONO, which is sensitive to the reaction with SF5-. The detection limit for the various trace gases is in the low 10 pptv range at a 1 s time resolution with an overall uncertainty of the measurement of the order of 20 %. AIMS has been integrated and successfully operated on the DLR research aircraft Falcon and HALO (High Altitude LOng range research aircraft). As an example, measurements conducted during the TACTS/ESMVal (Transport and Composition of the LMS/UT and Earth System Model Validation) mission with

The Atmosphere of Crystal Cave: Understanding Sources and Sinks of Trace Gases

NASA Astrophysics Data System (ADS)

Jarnot, A. W.; Hughes, S.; Blake, D. R.

2016-12-01

The atmospheric chemistry of cave systems has not been previously studied in depth; however, cave systems are prime locations to study potential sources and sinks for trace gas pollutants. Relatively constant temperatures, humidity, minimal air flow, and lack of sunlight create a stable environment that allows for biogeochemical processes to go on uninterrupted for extended periods of time. Carbonyl sulfide (OCS) is one of the main contributors to air pollution globally, but many OCS sinks are not fully understood. A preliminary analysis of cave air from Crystal Cave in Sequoia National Park yielded OCS concentrations of 35.2 ± 0.7 pptv, approximately 16 times lower than the average concentration of 568 ± 8 pptv measured outside of the cave. In addition, the concentrations of several other trace gases such as alpha-pinene and methyl bromide were found to be abnormally low (10.5 ± 0.3 pptv inside and 387 ± 8 pptv for alpha-pinene, and 387 ± 8 pptv inside and 11.1 ± 0.4 pptv outside for methyl bromide). The cave air was found to be well-mixed as the concentrations of long lived halocarbons such as CFC-12 were similar inside and outside of the cave (545 ± 5 pptv and 538 ± 4 pptv, respectively). This indicates that there may be one or more factors causing the cave to act a sink for several trace gas species. Further sampling and analysis of the atmosphere in the cave is required to draw any concrete conclusions about the unique environment presented here. The information gathered will help elucidate mechanisms for trace gas degradation, which could yield information about global trace gas budgets and their effect on global air quality.

Trace Gases and Aerosols Simulated Over the Indian Domain: Evaluation of the Model Wrf-Chem

NASA Astrophysics Data System (ADS)

Michael, M.; Yadav, A.; Tripathi, S. N.; Venkataraman, C.; Kanawade, V. P.

2012-12-01

As the anthropogenic emissions from the Asian countries contribute substantially to the global aerosol loading, the study of the distribution of trace gases and aerosols over this region has received increasing attention in recent years. In the present work, the aerosol properties over the Indian domain during the pre-monsoon season has been addressed. The "online" meteorological and chemical transport Weather Research and Forecasting-Chemistry (WRF-Chem) model has been implemented over Indian subcontinent for three consecutive summers in 2008, 2009 and 2010.The initial and boundary conditions are obtained from NCAR reanalysis data. The global emission inventories (REanalysis of the TROpospheric chemical composition (RETRO) and Emissions Database for Global Atmospheric Research (EDGAR)) have been used and are projected for the period of study using the method provided in Ohara et al. (2007). The emission rates of sulfur dioxide, black carbon, organic carbon and PM2.5 available in the global inventory are replaced with the high resolution emission inventory developed over India for the present study. The model simulates meteorological parameters, trace gases and particulate matter. Simulated mixing ratios of trace gases (Ozone, carbon monoxide, nitrogen oxides, and SO2) are compared with ground based as well as satellite observations over India with specific focus on Indo-Gangetic Plain. Simulated aerosol optical depth are in good agreement with those observed by Aerosol Robotic Network (AERONET). The vertical profiles of extinction coefficient have been compared with the Micro Pulse Lidar Network (MPLnet) data. The simulated mass concentration of BC shows very good agreement with those observed at a few ground stations. The vertical profiles of BC have also been compared with aircraft observations carried out during summer of 2008 and 2009, resulting in good agreement. This study shows that WRF-Chem model captures many important features of the observations and

WET EFFLUENT PARALLEL PLATE DIFFUSION DENUDER COUPLED CAPILLARY ION CHROMATOGRAPH FOR THE DETERMINATION OF ATMOSPHERIC TRACE GASES. (R825344)

EPA Science Inventory

We describe an inexpensive, compact parallel plate diffusion denuder coupled capillary IC system for the determination of soluble ionogenic atmospheric trace gases. The active sampling area (0.6×10 cm) of the denuder is formed in a novel manner by thermally bonding silica ge...

Application of ion chemistry and the SIFT technique to the quantitative analysis of trace gases in air and on breath

NASA Astrophysics Data System (ADS)

Smith, David; Španěl, Patrik

Our major objective in this paper is to describe a new method we have developed for the analysis of trace gases at partial pressures down to the ppb level in atmospheric air, with special emphasis on the detection and quantification of trace gases on human breath. It involves the use of our selected ion flow tube (Sift) technique which we previously developed and used extensively for the study of gas phase ionic reactions occurring in ionized media such as the terrestrial atmosphere and interstellar gas clouds. Before discussing this analytical technique we describe the results of our very recent Sift and flowing afterglow (FA) studies of the reactions of the H3O+ and OH- ions, of their hydrates H3O+(H2O)1,2,3 and OH- (H2O)1,2, and of NO+ and O2+, with several hydrocarbons and oxygen-bearing organic molecules, studies that are very relevant to our trace gas analytical studies. Then follows a detailed discussion of the application of our Sift technique to trace gas analysis, after which we present some results obtained for the analyses of laboratory air, the breath of a healthy non-smoking person, the breath of a person who regularly smokes cigarettes, the complex vapours emitted by banana and onion, and the molecules present in a butane/air flame. We show how the quantitative analysis of breath can be achieved from only a single exhalation and in real time (the time response of the instrument is only about 20 ms). We also show how the time variation of breath gases over long time periods can be followed, using the decay of ethanol on the breath after the ingestion of distilled liquor as an example, yet simultaneously following several other trace gases including acetone and isoprene which are very easily detected on the breath of all individuals because of their relatively high partial pressures (typically 100 to 1000 ppb). The breath of a smoker is richer in complex molecules, some nitrogen containing organics apparently being very evident at the 5 to 50 ppb level

Trans-Pacific transport and evolution of aerosols and trace gases from Asia during the INTEX-B field campaign

NASA Astrophysics Data System (ADS)

Adhikary, B.; Carmichael, G. R.; Kulkarni, S.; Wei, C.; Tang, Y.; Dallura, A.; Mena-Carrasco, M.; Streets, D. G.; Zhang, Q.; Pierce, R. B.; Al-Saadi, J. A.; Emmons, L. K.; Pfister, G. G.; Avery, M. A.; Barrick, J. D.; Blake, D. R.; Brune, W. H.; Cohen, R. C.; Dibb, J. E.; Fried, A.; Heikes, B. G.; Huey, L. G.; O'Sullivan, D. W.; Sachse, G. W.; Shetter, R. E.; Singh, H. B.; Campos, T. L.; Cantrell, C. A.; Flocke, F. M.; Dunlea, E. J.; Jimenez, J. L.; Weinheimer, A. J.; Crounse, J. D.; Wennberg, P. O.; Schauer, J. J.; Stone, E. A.; Jaffe, D. A.; Reidmiller, D. R.

2009-08-01

The Sulfur Transport and dEposition Model (STEM) developed at the University of Iowa is applied to the analysis of observations obtained during the Intercontinental Chemical Transport Experiment-Phase B (INTEX-B), conducted over the Pacific Ocean during the 2006 North American spring season. This paper reports on the model performance of meteorological parameters, trace gases, aerosols and photolysis rate (J-values) predictions with the NASA DC-8 and NSF/NCAR C-130 airborne measurements along with observations from three surface sites Mt. Bachelor, Trinidad Head and Kathmandu, Nepal. In general the model shows appreciable skill in predicting many of the important aspects of the observed distributions. The major meteorological parameters driving long range transport are accurately predicted by the WRF simulations used in this study. Furthermore, the STEM model predicts aerosols and trace gases concentrations within a standard deviation of most of the observed mean values. The results also point towards areas where model improvements are needed; e.g., the STEM model underestimates CO (15% for the DC8 and 6% for the C-130), whereas it overpredicts PAN (by a factor of two for both aircraft). The errors in the model calculations are attributed to uncertainty in emissions estimates and uncertainty in the top and lateral boundary conditions. Results from a series of sensitivity simulations examining the impact of the growth of emissions in Asia from 2000 to 2006, the importance of biomass burning, the effect of using boundary conditions from different global models, and the role of heterogeneous chemistry on the predictions are also presented. The impacts of heterogeneous reactions at specific times during dust transport episodes can be significant, and in the presence of dust both sulfate and nitrate aerosol production is increased and gas phase nitric acid levels are reduced appreciably (~50%). The aging of the air masses during the long range transport over the Pacific

LIDAR technology for measuring trace gases on Mars and Earth

NASA Astrophysics Data System (ADS)

Riris, H.; Abshire, J. B.; Graham, Allan; Hasselbrack, William; Rodriguez, Mike; Sun, Xiaoli; Weaver, Clark; Mao, Jianping; Kawa, Randy; Li, Steve; Numata, Kenji; Wu, Stewart

2017-11-01

Trace gases and their isotopic ratios in planetary atmospheres offer important but subtle clues as to the origins of a planet's atmosphere, hydrology, geology, and potential for biology. An orbiting laser remote sensing instrument is capable of measuring trace gases on a global scale with unprecedented accuracy, and higher spatial resolution that can be obtained by passive instruments. For Earth we have developed laser technique for the remote measurement of the tropospheric CO2, O2, and CH4 concentrations from space. Our goal is to develop a space instrument and mission approach for active CO2 measurements. Our technique uses several on and off-line wavelengths tuned to the CO2 and O2 absorption lines. This exploits the atmospheric pressure broadening of the gas lines to weigh the measurement sensitivity to the atmospheric column below 5 km and maximizes sensitivity to CO2 changes in the boundary layer where variations caused by surface sources and sinks are largest. Simultaneous measurements of O2 column use a selected region in the Oxygen A-band. Laser altimetry and atmospheric backscatter can also be measured simultaneously, which permits determining the surface height and measurements made to thick cloud tops and through aerosol layers. We use the same technique but with a different transmitter at 1.65 um to measure methane concentrations. Methane is also a very important trace gas on earth, and a stronger greenhouse gas than CO2 on a per molecule basis. Accurate, global observations are needed in order to better understand climate change and reduce the uncertainty in the carbon budget. Although carbon dioxide is currently the primary greenhouse gas of interest, methane can have a much larger impact on climate change. Methane levels have remained relatively constant over the last decade but recent observations in the Arctic have indicated that levels may be on the rise due to permafrost thawing. NASA's Decadal Survey underscored the importance of Methane as a

A study of atmospheric mixing of trace gases by aerial sampling with a multi-rotor drone

NASA Astrophysics Data System (ADS)

Chang, Chih-Chung; Chang, Chih-Yuan; Wang, Jia-Lin; Lin, Ming-Ren; Ou-Yang, Chang-Feng; Pan, Hsiang-Hsu; Chen, Yen-Chen

2018-07-01

We exploited a novel sampling vehicle, a multi-rotor drone carrying a remote-controlled whole air sampling device, to collect aerial samples with high sample integrity and preservation conditions. An array of 106 volatile organic compounds (VOCs), CO, CH4, and CO2 were analyzed and compared between the aerial samples (300-m height) and the ground-level samples in pairs to inspect for vertical mixing of the trace gases at a coastal site under three different meteorological conditions of local circulation, frontal passage, and high-pressure peripheral circulation. A rather homogeneous composition was observed for the sample pairs immediately after the frontal passage, indicating a well-mixed condition below 300 m. In contrast, inhomogeneous mixing was observed for the sample pairs under the other two conditions (local circulation and high-pressure peripheral circulation), suggesting different layers of air masses. Furthermore, information of unique source markers, composition profiles, and lifetimes of compounds were used to differentiate the origins of the air masses aloft and at the surface to substantiate the observed inhomogeneity. The study demonstrates that, with the availability of the near-surface aerial sampling coupling with in-laboratory analysis, detailed compositions of trace gases can now be readily obtained with superior data quality. Based on the distinctive chemical compositions, the sources, transport, and atmospheric mixing of the airborne pollutants in the near-surface atmosphere can be better studied and understood.

Gases and trace elements in soils at the North Silver Bell deposit, Pima County, Arizona

USGS Publications Warehouse

Hinkle, M.E.; Dilbert, C.A.

1984-01-01

Soil samples were collected over the North Silver Bell porphyry copper deposit near Tucson, Arizona. Volatile elements and compounds in gases derived from the soils and metallic elements in the soils were analyzed in order: (1) to see which volatile constituents of the soils might be indicative of the ore body or the alteration zones; and (2) to distinguish the ore and alteration zones by comparison of trace elements in the soil. Plots of analytical data on trace elements in soils indicated a typical distribution pattern for metals around a porphyry copper deposit, with copper, molybdenum, and arsenic concentrations higher over the ore body, and zinc, lead, and silver concentrations higher over the alteration zones. Higher than average concentrations of helium, carbon disulfide, and sulfur dioxide adsorbed on soils were found over the ore body, whereas higher concentrations of carbon dioxide and carbonyl sulfide were found over the alteration zones. ?? 1984.

Source apportionment of particulate matter and trace gases near a major refinery near the Houston Ship Channel

NASA Astrophysics Data System (ADS)

Wallace, Henry W.; Sanchez, Nancy P.; Flynn, James H.; Erickson, Mathew H.; Lefer, Barry L.; Griffin, Robert J.

2018-01-01

From February 7 to 27, 2015, a mobile air quality laboratory was deployed to a location proximate to a major refinery, the Port of Houston, and several neighborhoods to conduct measurements of atmospheric trace gases and particulate matter. Two statistical models were utilized to apportion the sources of pollution impacting this site and the denizens of the nearby neighborhoods. Positive matrix factorization (PMF) was performed on the organic signal of the aerosol mass spectra, resulting in five factors totaling an average of 4.1 μg/m3 of the organic aerosol: hydrocarbon-like (0.67 μg/m3), cooking (0.35 μg/m3) biomass burning (1.14 μg/m3), low-volatility oxidized (1.15 μg/m3), and semi-volatile oxidized (0.78 μg/m3). Principal component analysis was performed on daytime and nighttime data, including concentrations from PMF output, of other PM1 components, and of trace gases. This generated five daytime and five nighttime factors that explained 74.5% and 73.0% of the variance, respectively. The most important factors impacting this site were from mobile source exhaust and petrochemical aromatic compound emissions. Together these two factors also constitute most of the observed carcinogens.

Carbon Dioxide Information Analysis Center and World Data Center for Atmospheric Trace Gases, Fiscal Year 2002 Annual Report

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

Cushman, R.M.

2003-08-28

The Carbon Dioxide Information Analysis Center (CDIAC), which includes the World Data Center (WDC) for Atmospheric Trace Gases, is the primary global change data and information analysis center of the U.S. Department of Energy (DOE). More than just an archive of data sets and publications, CDIAC has, since its inception in 1982, enhanced the value of its holdings through intensive quality assurance, documentation, and integration. Whereas many traditional data centers are discipline-based (for example, meteorology or oceanography), CDIAC's scope includes potentially anything and everything that would be of value to users concerned with the greenhouse effect and global climate change,more » including atmospheric concentrations and atmospheric emissions of carbon dioxide (CO{sub 2}) and other radiatively active gases; the role of the terrestrial biosphere and the oceans in the biogeochemical cycles of greenhouse gases; long-term climate trends; the effects of elevated CO{sub 2} on vegetation; and the vulnerability of coastal areas to rising sea levels.« less

Satellite Observations of Trace Gases and Their Application for Studying Air Quality Near Oil and Gas Operations

NASA Astrophysics Data System (ADS)

Kollonige, D. E.; Thompson, A. M.; Nichols, M.; Fasnacht, Z.; Martins, D. K.; Dickerson, R. R.

2014-12-01

The increase in the natural gas component of the energy sector has led many state and local municipalities to begin regulation of emissions from the oil and natural gas operators with air quality (AQ) as a concern. "Top-down" measurements of trace gases in the air above wells complement "bottom-up" inventories, used by EPA and AQ stakeholders, through a more accurate depiction of regional variability of methane and other species near and downwind of oil and gas operations. Satellite observations of methane, nitrogen dioxide, formaldehyde, ozone, and other carbon gases enhance the spatial and temporal coverage of the data needed to demonstrate any long-term impacts from shale gas development. As part of a NASA AQAST (Air Quality Applied Sciences Team) project, we are evaluating satellite measurements of trace gases in regions with oil and gas operations for their application as a "top-down" constraint. For validation of the satellite instruments' sensitivities to emitted gases, we focus on regions where the DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) campaign deployed with ground and aircraft measurements, including, Maryland (2011), California and Texas (2013), and Colorado (2014). We compare vertical distributions of methane and volatile organic compounds (VOCs) nearby and downwind of oil and gas wells to locate any regional differences during the campaign time periods. This allows for better characterization of the satellite observations and their limitations for application in air quality studies in similar environments. Taking advantage of current EOS-era satellites' data records, we also analyze methane anomalies and gas correlations in the free troposphere from 2005 to present to identify trends for basins with oil and gas extraction sites and their influence on background concentrations downwind of wells. In most regions with oil and gas activity, we see continually

Spatial Variability of Trace Gases During DISCOVER-AQ: Planning for Geostationary Observations of Atmospheric Composition

NASA Technical Reports Server (NTRS)

Follette-Cook, Melanie B.; Pickering, K.; Crawford, J.; Appel, W.; Diskin, G.; Fried, A.; Loughner, C.; Pfister, G.; Weinheimer, A.

2015-01-01

Results from an in-depth analysis of trace gas variability in MD indicated that the variability in this region was large enough to be observable by a TEMPO-like instrument. The variability observed in MD is relatively similar to the other three campaigns with a few exceptions: CO variability in CA was much higher than in the other regions; HCHO variability in CA and CO was much lower; MD showed the lowest variability in NO2All model simulations do a reasonable job simulating O3 variability. For CO, the CACO simulations largely under over estimate the variability in the observations. The variability in HCHO is underestimated for every campaign. NO2 variability is slightly overestimated in MD, more so in CO. The TX simulation underestimates the variability in each trace gas. This is most likely due to missing emissions sources (C. Loughner, manuscript in preparation).Future Work: Where reasonable, we will use these model outputs to further explore the resolvability from space of these key trace gases using analyses of tropospheric column amounts relative to satellite precision requirements, similar to Follette-Cook et al. (2015).

Composition and Trends of Short-Lived Trace Gases in the UT/LS over Europe Observed by the CARIBIC Aircraft

NASA Astrophysics Data System (ADS)

Baker, A. K.; Brenninkmeijer, C. A.; Oram, D. E.; O'Sullivan, D. A.; Slemr, F.; Schuck, T. J.

2009-12-01

The CARIBIC project (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) involves the monthly deployment of an instrument container equipped to make atmospheric measurements from aboard a commercial airliner, and has operated since 2005 from aboard a Lufthansa Airbus 340-600 . Measurements from the container include in-situ trace gas and aerosol analyses and the collection of aerosol and whole air samples for post-flight laboratory analysis. Measurements made from the sampling flasks include greenhouse gas (GHG), halocarbon and nonmethane hydrocarbon (NMHC) analysis. CARIBIC flights originate in Frankfurt, Germany with routes to India, East Asia, South America, North America and Africa, and typical aircraft cruising altitudes of 10-12km allow for the monitoring of the upper troposphere/lower stratosphere (UT/LS) along these routes. Data collected during the aircraft’s departure from and return to Frankfurt provide a 4 year time series of near-monthly measurements of the composition of the UT/LS above Europe. Here we present a discussion of the composition of short-lived trace gases in the whole air samples collected above Europe during CARIBIC flights. Over 150 air samples were collected between May 2005 and July 2009, or about 4 samples per month. Of the whole air samples collected, about 45% showed influence by stratospheric air (i.e. very low values of GHG, NMHC and halocarbons, elevated O3, high potential vorticity). The remaining samples were representative of the upper troposphere; back trajectories for these samples indicate that a little over half were collected in air masses that had been in the boundary layer within the previous 8 days. The predominant source regions for these samples were the Gulf of Mexico and continental North America. Owing to their wide range of chemical lifetimes and the varying composition of emissions, short-lived trace gases transported to the UT/LS can be useful indicators of source

40 CFR 62.14103 - Emission limits for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.

Code of Federal Regulations, 2010 CFR

2010-07-01

... combustor metals, acid gases, organics, and nitrogen oxides. 62.14103 Section 62.14103 Protection of... combustor metals, acid gases, organics, and nitrogen oxides. (a) The emission limits for municipal waste combustor metals are specified in paragraphs (a)(1) through (a)(3) of this section. (1) The owner or...

Exomars orbiter science and data-relay mission / looking for trace gases on Mars

NASA Astrophysics Data System (ADS)

Fratacci, Olivier

EXOMARS Orbiter Module: looking for trace gas on Mars and providing data relay support for future Mars Surface assets O.Fratacci, M.Mesrine, H.Renault, Thales Alenia Space France B.Musetti, M.Montagna, Thales Alenia Space Italy M.Kesselmann, M.Barczewski OHB P.Mitschdoerfer, D.Dellantonio Euro-pean Space Agency / ESTEC The European Space Agency (ESA) in a joint cooperation with NASA, will launch in 2016 the EXOMARS spacecraft composite to develop European landing technologies and provide a science orbiter with data-relay capability around Mars until end 2022. The spacecraft composite is composed of the Orbitr Module (OM), provided by TAS-France, an entry descent and landing demonstrator module (EDM) provided by TAS-Italy, and a set of six scientific payloads to be selected by the JPL during 2010. Recent observations of the planet Mars have indicated detection of methane as well as temporal, perhaps spatial variability in the detected signal while current photochemical models cannot explain the presence of methane in the atmosphere of Mars nor its reported rapid variations in space and time. The triple scientific objectives that drive the selection of these six instruments for the Exomars 2016 mission is to detect trace gases in Mars atmosphere, to characterise their spatial and temporal variation and to explore the source of the key trace gases (e.g. methane) on the surface. The launch is scheduled in January 2016 from Kennedy Space Center (KSC) using an ATLAS V 421 launcher with a total launch mass of 4.4 tons. After release of the EDM on Mars, the OM will perform the Mars Orbit Insertion manoeuvre and then reduce its elliptic orbit by implementing the first European Aerobraking around Mars for about 6 to 9 months, to finally end on a circular 400x400km orbit with an altitude in the range of 350km to 420km. From this orbit, a science phase will follow lasting 2 years in which the Mars atmosphere and surface is continuously observed. Science instruments composed of

Fundamental Understanding of the Interaction of Acid Gases with CeO 2 : From Surface Science to Practical Catalysis

DOE PAGES

Tumuluri, Uma; Rother, Gernot; Wu, Zili

2016-03-21

Acid gases including CO 2, SO 2, and NO x are ubiquitous in large-scale energy applications including heterogeneous catalysis. The adverse environmental and health effects of these acid gases have resulted in high interest in the research and development of technologies to remove or convert these acid gases. The main challenge for the development of these technologies is to develop catalysts that are highly efficient, stable, and cost-effective, and many catalysts have been reported in this regard. CeO 2 and CeO 2-based catalysts have gained prominence in the removal and conversion of CO 2, SO 2, and NO x becausemore » of their structural robustness and redox and acid–base properties. In this article, we provide a brief overview of the application of CeO 2 and CeO 2-based catalysts for the removal of CO 2, SO 2, and NO x gases with an emphasis on the fundamental understanding of the interactions of these acid gases with CeO 2. The studies summarized in this review range from surface science using single crystals and thin films with precise crystallographic planes to practical catalysis applications of nanocrystalline and polycrystalline CeO 2 materials with defects and dopants. After an introduction to the properties of CeO 2 surfaces, their catalytic properties for conversions of different acid gases are reviewed and discussed. Lastly, we find that the surface atomic structure, oxygen vacancies, and surface acid–base properties of CeO 2 play vital roles in the surface chemistry and structure evolution during the interactions of acid gases with CeO 2 and CeO 2-based catalysts.« less

Fundamental Understanding of the Interaction of Acid Gases with CeO 2 : From Surface Science to Practical Catalysis

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

Tumuluri, Uma; Rother, Gernot; Wu, Zili

Acid gases including CO 2, SO 2, and NO x are ubiquitous in large-scale energy applications including heterogeneous catalysis. The adverse environmental and health effects of these acid gases have resulted in high interest in the research and development of technologies to remove or convert these acid gases. The main challenge for the development of these technologies is to develop catalysts that are highly efficient, stable, and cost-effective, and many catalysts have been reported in this regard. CeO 2 and CeO 2-based catalysts have gained prominence in the removal and conversion of CO 2, SO 2, and NO x becausemore » of their structural robustness and redox and acid–base properties. In this article, we provide a brief overview of the application of CeO 2 and CeO 2-based catalysts for the removal of CO 2, SO 2, and NO x gases with an emphasis on the fundamental understanding of the interactions of these acid gases with CeO 2. The studies summarized in this review range from surface science using single crystals and thin films with precise crystallographic planes to practical catalysis applications of nanocrystalline and polycrystalline CeO 2 materials with defects and dopants. After an introduction to the properties of CeO 2 surfaces, their catalytic properties for conversions of different acid gases are reviewed and discussed. Lastly, we find that the surface atomic structure, oxygen vacancies, and surface acid–base properties of CeO 2 play vital roles in the surface chemistry and structure evolution during the interactions of acid gases with CeO 2 and CeO 2-based catalysts.« less

40 CFR 60.52b - Standards for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.

Code of Federal Regulations, 2013 CFR

2013-07-01

... metals, acid gases, organics, and nitrogen oxides. 60.52b Section 60.52b Protection of Environment... § 60.52b Standards for municipal waste combustor metals, acid gases, organics, and nitrogen oxides. (a... (total mass), corrected to 7 percent oxygen. (d) The limits for nitrogen oxides are specified in...

40 CFR 60.52b - Standards for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.

Code of Federal Regulations, 2012 CFR

2012-07-01

... metals, acid gases, organics, and nitrogen oxides. 60.52b Section 60.52b Protection of Environment... § 60.52b Standards for municipal waste combustor metals, acid gases, organics, and nitrogen oxides. (a... (total mass), corrected to 7 percent oxygen. (d) The limits for nitrogen oxides are specified in...

40 CFR 60.52b - Standards for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.

Code of Federal Regulations, 2011 CFR

2011-07-01

... metals, acid gases, organics, and nitrogen oxides. 60.52b Section 60.52b Protection of Environment... § 60.52b Standards for municipal waste combustor metals, acid gases, organics, and nitrogen oxides. (a... (total mass), corrected to 7 percent oxygen. (d) The limits for nitrogen oxides are specified in...

40 CFR 60.52b - Standards for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.

Code of Federal Regulations, 2014 CFR

2014-07-01

... metals, acid gases, organics, and nitrogen oxides. 60.52b Section 60.52b Protection of Environment... § 60.52b Standards for municipal waste combustor metals, acid gases, organics, and nitrogen oxides. (a... (total mass), corrected to 7 percent oxygen. (d) The limits for nitrogen oxides are specified in...

Trends in source gases

NASA Technical Reports Server (NTRS)

Ehhalt, D. H.; Fraser, P. J.; Albritton, D.; Cicerone, R. J.; Khalil, M. A. K.; Legrand, M.; Makide, Y.; Rowland, F. S.; Steele, L. P.; Zander, R.

1989-01-01

Source gases are defined as those gases that, by their breakdown, introduce into the stratosphere halogen, hydrogen, and nitrogen compounds that are important in stratospheric ozone destruction. Given here is an update of the existing concentration time series for chlorocarbons, nitrous oxide, and methane. Also reviewed is information on halogen containing species and the use of these data for establishing trends. Also reviewed is evidence on trends in trace gases that influence tropospheric chemistry and thus the tropospheric lifetimes of source gases, such as carbon dioxide, carbon monoxide, or nitrogen oxides. Much of the information is given in tabular form.

Microwave limb sounder. [measuring trace gases in the upper atmosphere

NASA Technical Reports Server (NTRS)

Gustincic, J. J. (Inventor)

1981-01-01

Trace gases in the upper atmosphere can be measured by comparing spectral noise content of limb soundings with the spectral noise content of cold space. An offset Cassegrain antenna system and tiltable input mirror alternately look out at the limb and up at cold space at an elevation angle of about 22. The mirror can also be tilted to look at a black body calibration target. Reflection from the mirror is directed into a radiometer whose head functions as a diplexer to combine the input radiation and a local ocillator (klystron) beam. The radiometer head is comprised of a Fabry-Perot resonator consisting of two Fabry-Perot cavities spaced a number of half wavelengths apart. Incoming radiation received on one side is reflected and rotated 90 deg in polarization by the resonator so that it will be reflected by an input grid into a mixer, while the klystron beam received on the other side is also reflected and rotated 90 deg, but not without passing some energy to be reflected by the input grid into the mixer.

Tracing enhanced oil recovery signatures in casing gases from the Lost Hills oil field using noble gases

USGS Publications Warehouse

Barry, Peter H.; Kulongoski, Justin; Landon, Matthew K.; Tyne, R.L.; Gillespie, Janice; Stephens, Michael; Hillegonds, D.J.; Byrne, D.J.; Ballentine, C.J.

2018-01-01

Enhanced oil recovery (EOR) and hydraulic fracturing practices are commonly used methods to improve hydrocarbon extraction efficiency; however the environmental impacts of such practices remain poorly understood. EOR is particularly prevalent in oil fields throughout California where water resources are in high demand and disposal of high volumes of produced water may affect groundwater quality. Consequently, it is essential to better understand the fate of injected (EOR) fluids in California and other subsurface petroleum systems, as well as any potential effect on nearby aquifer systems. Noble gases can be used as tracers to understand hydrocarbon generation, migration, and storage conditions, as well as the relative proportions of oil and water present in the subsurface. In addition, a noble gas signature diagnostic of injected (EOR) fluids can be readily identified. We report noble gas isotope and concentration data in casing gases from oil production wells in the Lost Hills oil field, northwest of Bakersfield, California, and injectate gas data from the Fruitvale oil field, located within the city of Bakersfield. Casing and injectate gas data are used to: 1) establish pristine hydrocarbon noble-gas signatures and the processes controlling noble gas distributions, 2) characterize the noble gas signature of injectate fluids, 3) trace injectate fluids in the subsurface, and 4) construct a model to estimate EOR efficiency. Noble gas results range from pristine to significantly modified by EOR, and can be best explained using a solubility exchange model between oil and connate/formation fluids, followed by gas exsolution upon production. This model is sensitive to oil-water interaction during hydrocarbon expulsion, migration, and storage at reservoir conditions, as well as any subsequent modification by EOR.

Response of trace gases to the disrupted 2015-2016 quasi-biennial oscillation

NASA Astrophysics Data System (ADS)

Tweedy, Olga V.; Kramarova, Natalya A.; Strahan, Susan E.; Newman, Paul A.; Coy, Lawrence; Randel, William J.; Park, Mijeong; Waugh, Darryn W.; Frith, Stacey M.

2017-06-01

The quasi-biennial oscillation (QBO) is a quasiperiodic alternation between easterly and westerly zonal winds in the tropical stratosphere, propagating downward from the middle stratosphere to the tropopause with a period that varies from 24 to 32 months ( ˜ 28 months on average). The QBO wind oscillations affect the distribution of chemical constituents, such as ozone (O3), water vapor (H2O), nitrous oxide (N2O), and hydrochloric acid (HCl), through the QBO-induced meridional circulation. In the 2015-2016 winter, radiosonde observations revealed an anomaly in the downward propagation of the westerly phase, which was disrupted by the upward displacement of the westerly phase from ˜ 30 hPa up to 15 hPa and the sudden appearance of easterlies at 40 hPa. Such a disruption is unprecedented in the observational record from 1953 to the present. In this study we show the response of trace gases to this QBO disruption using O3, HCl, H2O, and temperature from the Aura Microwave Limb Sounder (MLS) and total ozone measurements from the Solar Backscatter Ultraviolet (SBUV) Merged Ozone Data Set (MOD). Results reveal the development of positive anomalies in stratospheric equatorial O3 and HCl over ˜ 50-30 hPa in May-September of 2016 and a substantial decrease in O3 in the subtropics of both hemispheres. The SBUV observations show near-record low levels of column ozone in the subtropics in 2016, resulting in an increase in the surface UV index during northern summer. Furthermore, cold temperature anomalies near the tropical tropopause result in a global decrease in stratospheric water vapor.

Measuring fluxes of trace gases and energy between ecosystems and the atmosphere - the state and future of the eddy covariance method.

PubMed

Baldocchi, Dennis

2014-12-01

The application of the eddy covariance flux method to measure fluxes of trace gas and energy between ecosystems and the atmosphere has exploded over the past 25 years. This opinion paper provides a perspective on the contributions and future opportunities of the eddy covariance method. First, the paper discusses the pros and cons of this method relative to other methods used to measure the exchange of trace gases between ecosystems and the atmosphere. Second, it discusses how the use of eddy covariance method has grown and evolved. Today, more than 400 flux measurement sites are operating world-wide and the duration of the time series exceed a decade at dozens of sites. Networks of tower sites now enable scientists to ask scientific questions related to climatic and ecological gradients, disturbance, changes in land use, and management. The paper ends with discussions on where the field of flux measurement is heading. Topics discussed include role of open access data sharing and data mining, in this new era of big data, and opportunities new sensors that measure a variety of trace gases, like volatile organic carbon compounds, methane and nitrous oxide, and aerosols, may yield. © 2014 John Wiley & Sons Ltd.

An approach for retrieval of atmospheric trace gases CO II, CH 4 and CO from the future Canadian micro earth observation satellite (MEOS)

NASA Astrophysics Data System (ADS)

Trishchenko, Alexander P.; Khlopenkov, Konstantin V.; Wang, Shusen; Luo, Yi; Kruzelecky, Roman V.; Jamroz, Wes; Kroupnik, Guennadi

2007-10-01

Among all trace gases, the carbon dioxide and methane provide the largest contribution to the climate radiative forcing and together with carbon monoxide also to the global atmospheric carbon budget. New Micro Earth Observation Satellite (MEOS) mission is proposed to obtain information about these gases along with some other mission's objectives related to studying cloud and aerosol interactions. The miniature suit of instruments is proposed to make measurements with reduced spectral resolution (1.2nm) over wide NIR range 0.9μm to 2.45μm and with high spectral resolution (0.03nm) for three selected regions: oxygen A-band, 1.5μm-1.7μm band and 2.2μm-2.4μm band. It is also planned to supplement the spectrometer measurements with high spatial resolution imager for detailed characterization of cloud and surface albedo distribution within spectrometer field of view. The approaches for cloud/clear-sky identification and column retrievals of above trace gases are based on differential absorption technique and employ the combination of coarse and high-resolution spectral data. The combination of high and coarse resolution spectral data is beneficial for better characterization of surface spectral albedo and aerosol effects. An additional capability for retrieval of the vertical distribution amounts is obtained from the combination of nadir and limb measurements. Oxygen A-band path length will be used for normalization of trace gas retrievals.

Measurements of Trace Gases in the Tropical Tropopause Layer

NASA Technical Reports Server (NTRS)

Marcy, T. P.; Popp, P. J.; Gao, R. S.; Fahey, D. W.; Ray, E. A.; Richard, E. C.; Thompson, T. L.; Atlas, E. L.; Lowenstein, M.; Wofsy, S. C.;

Quantification of Aerosol Derived Particulate Matter and Trace gases in the Coastal Belt of Kochi, Kerala, India

NASA Astrophysics Data System (ADS)

H, S. C.

2016-02-01

Aerosol chemistry is a window to unravel the various environmental health hazard problems. This open forum which deals with the study of formation, interaction, transformation of aerosol species, which could enable in the assessment of biogeochemical cycling of anthropogenic and toxic species. It also preserves the temperature balance and reservoir and sink for nutrients, trace metals and organic species. An inventory of air pollutants is a proactive and necessary first step towards the control of air pollution. Surveys and studies on the sources of pollution and their apportionment to different sources are a pre-requisite for alleviating environmental disorder. The Kochi City (The Queen of Arabian Sea), Kerala, India is a fast growing industrial region where mounting urbanization has been affecting the quality of the atmospheric environment. Cochin estuarine environment is progressively affected by marine pollution concomitant by industrial hazardous chemicals and municipal waste. Further, rapid urbanization and industrialization has lead to lofting and large scale advection of these omnipresent species in the atmosphere. Studies were conducted to assess the significance and potential impact occupied to these ubiquitous species. The major gaseous pollutants include gases like sulphur dioxide, nitrogen dioxide, ammonia and particulate matter (PM). An attempt was performed to unravel the inorganic species in the atmosphere and programmed by means of quantification of PM10 and trace gases. Their distribution pattern and outcomes are inferred.

Atmos/Atlas 3 Infrared Profile Measurements of Trace Gases in The November 1994 Tropical and Subtropical Upper Troposphere

NASA Technical Reports Server (NTRS)

Rinsland, C. P.; Gunson, M. R.; Wang, P.-H.; Arduini, R. F.; Baum, B. A.; Minnis, P.; Minnis, P.; Goldman, A.; Abrams, M. C.; Zander, R.;

40 CFR 60.33b - Emission guidelines for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.

Code of Federal Regulations, 2012 CFR

2012-07-01

... combustor metals, acid gases, organics, and nitrogen oxides. 60.33b Section 60.33b Protection of Environment..., acid gases, organics, and nitrogen oxides. (a) The emission limits for municipal waste combustor metals... oxygen. (d) For approval, a State plan shall include emission limits for nitrogen oxides at least as...

40 CFR 60.33b - Emission guidelines for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.

Code of Federal Regulations, 2013 CFR

2013-07-01

... combustor metals, acid gases, organics, and nitrogen oxides. 60.33b Section 60.33b Protection of Environment..., acid gases, organics, and nitrogen oxides. (a) The emission limits for municipal waste combustor metals... oxygen. (d) For approval, a State plan shall include emission limits for nitrogen oxides at least as...

40 CFR 60.33b - Emission guidelines for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.

Code of Federal Regulations, 2011 CFR

2011-07-01

... combustor metals, acid gases, organics, and nitrogen oxides. 60.33b Section 60.33b Protection of Environment..., acid gases, organics, and nitrogen oxides. (a) The emission limits for municipal waste combustor metals... oxygen. (d) For approval, a State plan shall include emission limits for nitrogen oxides at least as...

40 CFR 60.33b - Emission guidelines for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.

Code of Federal Regulations, 2014 CFR

2014-07-01

... combustor metals, acid gases, organics, and nitrogen oxides. 60.33b Section 60.33b Protection of Environment..., acid gases, organics, and nitrogen oxides. (a) The emission limits for municipal waste combustor metals... oxygen. (d) For approval, a State plan shall include emission limits for nitrogen oxides at least as...

Clostridium stain which produces acetic acid from waste gases

DOEpatents

Gaddy, James L.

1997-01-01

A method and apparatus for converting waste gases from industrial processes such as oil refining, carbon black, coke, ammonia, and methanol production, into useful products. The method includes introducing the waste gases into a bioreactor where they are fermented to various organic acids or alcohols by anaerobic bacteria within the bioreactor. These valuable end products are then recovered, separated and purified. In an exemplary recovery process, the bioreactor raffinate is passed through an extraction chamber into which one or more non-inhibitory solvents are simultaneously introduced to extract the product. Then, the product is separated from the solvent by distillation. Gas conversion rates can be maximized by use of centrifuges, hollow fiber membranes, or other means of ultrafiltration to return entrained anaerobic bacteria from the bioreactor raffinate to the bioreactor itself, thus insuring the highest possible cell concentration.

Clostridium strain which produces acetic acid from waste gases

DOEpatents

Gaddy, J.L.

1997-01-14

A method and apparatus are disclosed for converting waste gases from industrial processes such as oil refining, carbon black, coke, ammonia, and methanol production, into useful products. The method includes introducing the waste gases into a bioreactor where they are fermented to various organic acids or alcohols by anaerobic bacteria within the bioreactor. These valuable end products are then recovered, separated and purified. In an exemplary recovery process, the bioreactor raffinate is passed through an extraction chamber into which one or more non-inhibitory solvents are simultaneously introduced to extract the product. Then, the product is separated from the solvent by distillation. Gas conversion rates can be maximized by use of centrifuges, hollow fiber membranes, or other means of ultrafiltration to return entrained anaerobic bacteria from the bioreactor raffinate to the bioreactor itself, thus insuring the highest possible cell concentration. 4 figs.

The airborne mass spectrometer AIMS - Part 2: Measurements of trace gases with stratospheric or tropospheric origin in the UTLS

NASA Astrophysics Data System (ADS)

Jurkat, T.; Kaufmann, S.; Voigt, C.; Schäuble, D.; Jeßberger, P.; Ziereis, H.

2015-12-01

Understanding the role of climate-sensitive trace gas variabilities in the upper troposphere and lower stratosphere region (UTLS) and their impact on its radiative budget requires accurate measurements. The composition of the UTLS is governed by transport and chemistry of stratospheric and tropospheric constituents, such as chlorine, nitrogen oxide and sulphur components. The Airborne chemical Ionization Mass Spectrometer AIMS has been developed to accurately measure a set of these constituents on aircraft by means of chemical ionization. Here we present a setup using chemical ionization with SF5- reagent ions for the simultaneous measurement of trace gas concentrations in the pptv to ppmv (10-12 to 10-6 mol mol-1) range of HCl, HNO3 and SO2 with in-flight and online calibration called AIMS-TG. Part 1 of this paper (Kaufmann et al., 2015) reports on the UTLS water vapour measurements with the AIMS-H2O configuration. The instrument can be flexibly switched between two configurations depending on the scientific objective of the mission. For AIMS-TG, a custom-made gas discharge ion source has been developed generating a characteristic ionization scheme. HNO3 and HCl are routinely calibrated in-flight using permeation devices, SO2 is permanently calibrated during flight adding an isotopically labelled 34SO2 standard. In addition, we report on trace gas measurements of HONO which is sensitive to the reaction with SF5-. The detection limit for the various trace gases is in the low ten pptv range at a 1 s time resolution with an overall uncertainty of the measurement in the order of 20 %. AIMS has been integrated and successfully operated on the DLR research aircraft Falcon and HALO. Exemplarily, measurements conducted during the TACTS/ESMVal mission with HALO in 2012 are presented, focusing on a classification of tropospheric and stratospheric influences in the UTLS region. Comparison of AIMS measurements with other measurement techniques allow to draw a comprehensive

OH reactivity and potential SOA yields from volatile organic compounds and other trace gases measured in controlled laboratory biomass burns

Treesearch

J. B. Gilman; C. Warneke; W. C. Kuster; P. D. Goldan; P. R. Veres; J. M. Roberts; J. A. de Gouw; I. R. Burling; R. J. Yokelson

2010-01-01

A comprehensive suite of instruments were used to characterize volatile organic compounds (VOCs) and other trace gases (e.g., CO, CH4, NO2, etc.) emitted from controlled burns of various fuel types common to the Southeastern and Southwestern United States. These laboratory-based measurements were conducted in February 2009 at the U.S. Department of Agriculture’s Fire...

Nighttime chemical evolution of aerosol and trace gases in a power plant plume: Implications for secondary organic nitrate and organosulfate aerosol formation, NO₃ radical chemistry, and N₂O₅ heterogeneous hydrolysis

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

Zaveri, Rahul A.; Berkowitz, Carl M.; Brechtel, Fred J.

Chemical evolution of aerosols and trace gases in the Salem Harbor power plant plume was monitored with the DOE G-1 aircraft on the night of July 30-31, 2002. Quasi-Lagrangian sampling in the plume at increasing downwind distances/processing times was guided by a constant-volume tetroon that was released near the power plant at sunset. While no evidence of fly ash particles was found, concentrations of particulate organics, sulfate, and nitrate were higher in the plume than in the nearby background air. These species were internally mixed and the particles were acidic, suggesting that particulate nitrate was in the form of organicmore » nitrate. The enhanced particulate organic and nitrate masses in the plume were inferred to be as secondary organic aerosol, possibly formed from the NO3 radical-initiated oxidation of isoprene and other trace organic gases in the presence of acidic sulfate particles. The enhanced particulate sulfate concentrations observed in the plume were attributed to direct emissions of gaseous SO3/H2SO4 from the power plant. Furthermore, concentration of nucleation mode particles was significantly higher in the plume than in background air, suggesting that some of the emitted H2SO4 had nucleated to form new particles. Spectromicroscopic analyses of particle samples suggested that some sulfate was likely in the form of organosulfates. Constrained Lagrangian model analysis of the aircraft and tetroon observations showed that heterogeneous hydrolysis of N2O5 was negligibly slow. These results have significant implications for several scientific and regulatory issues related to the impacts of power plant emissions on atmospheric chemistry, air quality, visibility, and climate.« less

Analysis and Modeling of Trace Gases and Aerosols in Severe Convection: The 22 June 2012 DC3 Case

NASA Astrophysics Data System (ADS)

Barth, M. C.; Apel, E. C.; Bela, M.; Fried, A.; Fuchs, B.; Pickering, K. E.; Pollack, I. B.; Rutledge, S. A.

2016-12-01

The Deep Convective Clouds and Chemistry (DC3) field campaign aimed to quantify and characterize the dynamics, physics, lightning, and transport of trace gases and aerosols in convection, as well as the chemical aging of convective outflow plumes in the upper troposphere. These goals were met by deploying radars, lightning mapping arrays, weather balloons, and aircraft to sample storms in northeast Colorado, west Texas to central Oklahoma, and northern Alabama. Here, we use one case, 22 June 2012 severe convection in northeast Colorado and southwest Nebraska, as an example for quantifying and predicting convective transport of trace gases and aerosols, lightning flash rate, lightning production of nitrogen oxides, and subsequent ozone production downwind of the storms. This case was unique in that one severe storm ingested a wildfire smoke plume at 7 km altitude while other storms in the area did not. Several analyses of this case have been done using the aircraft composition measurements, dual-Doppler and polarimetric radar products, and lightning mapping array data. It was determined that the storm unaffected by the High Park fire smoke plume had a 4.8±0.9%/km entrainment rate and estimated scavenging efficiencies of CH2O, H2O2, CH3OOH, SO2, and HNO3 of 41±4%, 79±19, 44±47%, 92±4%, 95±12%, respectively. Total (intracloud and cloud-to-ground) lightning flash rates were 98-106 flashes per minute when the aircraft were sampling the outflow of the storms, resulting in an estimate of lightning-NOx production of 142±25 moles NO per flash. Box modeling simulations estimate the production of O3 in the convective outflow of these storms to be 11-14 ppbv over 2 days. These results are used to evaluate the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to learn how well a state-of-the-art model represents the storm processing of trace gases. The WRF-Chem simulations are analyzed further to examine the effect of aerosols in the smoke plume on

Origin, speciation, and fluxes of trace-element gases at Augustine volcano, Alaska: Insights into magma degassing and fumarolic processes

NASA Astrophysics Data System (ADS)

Symonds, Robert B.; Reed, Mark H.; Rose, William I.

1992-02-01

Thermochemical modeling predicts that trace elements in the Augustine gas are transported from near-surface magma as simple chloride (NaCl, KCl, FeCl 2, ZnCl 2, PbCl 2, CuCl, SbCl 3, LiCl, MnCl 2, NiCl 2, BiCl, SrCl 2), oxychloride (MoO 2Cl 2), sulfide (AsS), and elemental (Cd) gas species. However, Si, Ca, Al, Mg, Ti, V, and Cr are actually more concentrated in solids, beta-quartz (SiO 2), wollastonite (CaSiO 3), anorthite (CaAl 2Si 2O 8), diopside (CaMgSi 2O 6), sphene (CaTiSiO 5), V 2O 3(c), and Cr 2O 3(c), respectively, than in their most abundant gaseous species, SiF 4, CaCl 2, AlF 2O, MgCl 2 TiCl 4, VOCl 3, and CrO 2Cl 2. These computed solids are not degassing products, but reflect contaminants in our gas condensates or possible problems with our modeling due to "missing" gas species in the thermochemical data base. Using the calculated distribution of gas species and the COSPEC SO 2 fluxes, we have estimated the emission rates for many species (e.g., COS, NaCl, KCl, HBr, AsS, CuCl). Such forecasts could be useful to evaluate the effects of these trace species on atmospheric chemistry. Because of the high volatility of metal chlorides (e.g., FeCl 2, NaCl, KCl, MnCl 2, CuCl), the extremely HCl-rich Augustine volcanic gases are favorable for transporting metals from magma. Thermochemical modeling shows that equilibrium degassing of magma near 870°C can account for the concentrations of Fe, Na, K, Mn, Cu, Ni and part of the Mg in the gases escaping from the dome fumaroles on the 1986 lava dome. These calculations also explain why gases escaping from the lower temperature but highly oxidized moat vents on the 1976 lava dome should transport less Fe, Na, K, Mn and Ni, but more Cu; oxidation may also account for the larger concentrations of Zn and Mo in the moat gases. Nonvolatile elements (e.g., Al, Ca, Ti, Si) in the gas condensates came from eroded rock particles that dissolved in our samples or, for Si, from contamination from the silica sampling tube. Only a

Oil and gas exploration system and method for detecting trace amounts of hydrocarbon gases in the atmosphere

DOEpatents

Wamsley, Paula R.; Weimer, Carl S.; Nelson, Loren D.; O'Brien, Martin J.

2003-01-01

An oil and gas exploration system and method for land and airborne operations, the system and method used for locating subsurface hydrocarbon deposits based upon a remote detection of trace amounts of gases in the atmosphere. The detection of one or more target gases in the atmosphere is used to indicate a possible subsurface oil and gas deposit. By mapping a plurality of gas targets over a selected survey area, the survey area can be analyzed for measurable concentration anomalies. The anomalies are interpreted along with other exploration data to evaluate the value of an underground deposit. The system includes a differential absorption lidar (DIAL) system with a spectroscopic grade laser light and a light detector. The laser light is continuously tunable in a mid-infrared range, 2 to 5 micrometers, for choosing appropriate wavelengths to measure different gases and avoid absorption bands of interference gases. The laser light has sufficient optical energy to measure atmospheric concentrations of a gas over a path as long as a mile and greater. The detection of the gas is based on optical absorption measurements at specific wavelengths in the open atmosphere. Light that is detected using the light detector contains an absorption signature acquired as the light travels through the atmosphere from the laser source and back to the light detector. The absorption signature of each gas is processed and then analyzed to determine if a potential anomaly exists.

Detection of Matrix Elements and Trace Impurities in Cu(In, Ga)Se2 Photovoltaic Absorbers Using Surface Analytical Techniques.

PubMed

Kim, Min Jung; Lee, Jihye; Kim, Seon Hee; Kim, Haidong; Lee, Kang-Bong; Lee, Yeonhee

2015-10-01

Chalcopyrite Cu(In, Ga)Se2 (CIGS) thin films are well known as the next-generation solar cell materials notable for their high absorption coefficient for solar radiation, suitable band gap, and ability for deposition on flexible substrate materials, allowing the production of highly flexible and lightweight solar panels. To improve solar cell performances, a quantitative and depth-resolved elemental analysis of photovoltaic thin films is much needed. In this study, Cu(In, Ga)Se2 thin films were prepared on molybdenum back contacts deposited on soda-lime glass substrates via three-stage evaporation. Surface analyses via AES and SIMS were used to characterize the CIGS thin films and compare their depth profiles. We determined the average concentration of the matrix elements, Cu, In, Ga, and Se, using ICP-AES, XRF, and EPMA. We also obtained depth profiling results using TOF-SIMS, magnetic sector SIMS and AES, and APT, a sub-nanometer resolution characterization technique that enables three-dimensional elemental mapping. The SIMS technique, with its high detection limit and ability to obtain the profiles of elements in parallel, is a powerful tool for monitoring trace elements in CIGS thin films. To identify impurities in a CIGS layer, the distribution of trace elements was also observed according to depth by SIMS and APT.

Knudsen cell: Investigations about the uptake of important traces gases on ambient airborne mineral dust

NASA Astrophysics Data System (ADS)

Horn, Sabrina; Herrmann, Hartmut

2013-04-01

Mineral dust constitutes one of the largest mass fractions of natural aerosol. Its emission is estimated between 800 - 2000 Tg/a]. The dust is emitted through sand and dust storms in the arid regions of our planet, in particular by the great desserts such as the Sahara. The complex chemical composition of mineral dust is similar to crust material, because the dust is produced by soil erosion. The main components of mineral dust are SiO2 and Al2O3, whereas the active oxides (Fe2O3, TiO2) show some variety in content due to the dust source region. Mineral dust particles can be transported over several 1000 km and during its transport the surface can be changed by the uptake of water vapor and trace gases. On such modified surfaces homo- and heterogeneous reactions can occur. Trace gas uptakes play an important role in atmospheric chemistry as sinks or sources for several gaseous species. Hence, it is necessary to study these reactions. Among several experimental setups, the Knudsen cell is one of the promising tools to study reactive uptakes from the gas phase and the release of products formed by dust surface-mediated reactions. The Knudsen cell, implemented by Golden et al. in 1975, is a high vacuum flow reactor operating under molecular flow conditions, i.e., gas-wall collisions are highly preferred over gas-gas collisions. Despite several Knudsen cell studies examining the reaction between different traces gases and model dust surfaces constituted of not more than a few components, no measurements utilizing collected ambient mineral dust are done so far. For a better understanding of the chemistry on mineral dust surfaces gas uptake measurements will be done with a Knudsen cell. The first measurements are done with isopropanol on TiO2. Afterwards there are studies with different substrates like, Al2O3 (α- and γ-phase), FeO2, Arizona test dust, air collected mineral dust from the Cap Verde islands. In the beginning SO2, NO2 and HNO3 will be used.

Trace element geochemistry of volcanic gases and particles from 1983-1984 eruptive episodes of Kilauea Volcano

NASA Astrophysics Data System (ADS)

Crowe, Bruce M.; Finnegan, David L.; Zoller, William H.; Boynton, William V.

1987-12-01

Compositional data have been obtained for volcanic gases and particles collected from fume emitted at the Pu'u O'o vent on the east rift zone of Kilauea volcano. The samples were collected by pumping fume through a filter pack system consisting of a front stage particulate filter followed by four base-treated filters (7LiOH). Particles and condensed phases are trapped on the particulate filter, and acidic gases are collected on the treated filters. The filters are analyzed for 30 elements by instrumental neutron activation analysis. Fume samples were collected from the Pu'u O'o vent for two eruptive episodes: (1) 7 days after episode 11 (cooling vent samples) and (2) the waning stage of episode 13 (active vent samples). Additional samples were collected by aircraft from the gas plume released during the lava fountaining phase of episode 17 (aircraft samples). Element concentrations in the vent gases were > 104 μg m-3 for S, Cl, and F. Enrichment factors (EFs) for the volcanic fume versus the source magma were calculated using the volatile element Br as the reference element for normalization and the U.S. Geological Survey standard BHVO-1 as the magma standard. This removes the ash dilution effect obtained by using an ash constituent (Al, Sc, or Mg) as the reference element. Bromine-normalized EFs (× 105) range from 101 to 102 for Na, K, and Cu; 102 to 105 for Zn, W, Sb, In, Ir, Ag, F, and As; and > 105 for Au, Cd, Re, Cl, Se, and S. The highest enrichment factors are for aircraft samples collected during the most gas-rich phase of an eruption cycle. Metal and volatile-element data form two groups: (1) elements showing little or no variation in abundance ratios with sample type (group 1: Cl, Br, and Re) and (2) elements that show significant variation in abundance ratios by sample type (group 2: Zn, W, Sb, In, Ir, Au, and Cd). Bivariate plots of elements of the first group versus elements of the second group separate by sample type. The separation corresponds to

Characteristics of Fine Particles in an Urban Atmosphere-Relationships with Meteorological Parameters and Trace Gases.

PubMed

Zhang, Tianhao; Zhu, Zhongmin; Gong, Wei; Xiang, Hao; Fang, Ruimin

2016-08-10

Atmospheric fine particles (diameter < 1 μm) attract a growing global health concern and have increased in urban areas that have a strong link to nucleation, traffic emissions, and industrial emissions. To reveal the characteristics of fine particles in an industrial city of a developing country, two-year measurements of particle number size distribution (15.1 nm-661 nm), meteorological parameters, and trace gases were made in the city of Wuhan located in central China from June 2012 to May 2014. The annual average particle number concentrations in the nucleation mode (15.1 nm-30 nm), Aitken mode (30 nm-100 nm), and accumulation mode (100 nm-661 nm) reached 4923 cm(-3), 12193 cm(-3) and 4801 cm(-3), respectively. Based on Pearson coefficients between particle number concentrations and meteorological parameters, precipitation and temperature both had significantly negative relationships with particle number concentrations, whereas atmospheric pressure was positively correlated with the particle number concentrations. The diurnal variation of number concentration in nucleation mode particles correlated closely with photochemical processes in all four seasons. At the same time, distinct growth of particles from nucleation mode to Aitken mode was only found in spring, summer, and autumn. The two peaks of Aitken mode and accumulation mode particles in morning and evening corresponded obviously to traffic exhaust emissions peaks. A phenomenon of "repeated, short-lived" nucleation events have been created to explain the durability of high particle concentrations, which was instigated by exogenous pollutants, during winter in a case analysis of Wuhan. Measurements of hourly trace gases and segmental meteorological factors were applied as proxies for complex chemical reactions and dense industrial activities. The results of this study offer reasonable estimations of particle impacts and provide references for emissions control strategies in industrial cities of developing

Characteristics of Fine Particles in an Urban Atmosphere—Relationships with Meteorological Parameters and Trace Gases

PubMed Central

Zhang, Tianhao; Zhu, Zhongmin; Gong, Wei; Xiang, Hao; Fang, Ruimin

2016-01-01

Atmospheric fine particles (diameter < 1 μm) attract a growing global health concern and have increased in urban areas that have a strong link to nucleation, traffic emissions, and industrial emissions. To reveal the characteristics of fine particles in an industrial city of a developing country, two-year measurements of particle number size distribution (15.1 nm–661 nm), meteorological parameters, and trace gases were made in the city of Wuhan located in central China from June 2012 to May 2014. The annual average particle number concentrations in the nucleation mode (15.1 nm–30 nm), Aitken mode (30 nm–100 nm), and accumulation mode (100 nm–661 nm) reached 4923 cm−3, 12193 cm−3 and 4801 cm−3, respectively. Based on Pearson coefficients between particle number concentrations and meteorological parameters, precipitation and temperature both had significantly negative relationships with particle number concentrations, whereas atmospheric pressure was positively correlated with the particle number concentrations. The diurnal variation of number concentration in nucleation mode particles correlated closely with photochemical processes in all four seasons. At the same time, distinct growth of particles from nucleation mode to Aitken mode was only found in spring, summer, and autumn. The two peaks of Aitken mode and accumulation mode particles in morning and evening corresponded obviously to traffic exhaust emissions peaks. A phenomenon of “repeated, short-lived” nucleation events have been created to explain the durability of high particle concentrations, which was instigated by exogenous pollutants, during winter in a case analysis of Wuhan. Measurements of hourly trace gases and segmental meteorological factors were applied as proxies for complex chemical reactions and dense industrial activities. The results of this study offer reasonable estimations of particle impacts and provide references for emissions control strategies in industrial cities of

Marine cycling of the climate relevant trace gases carbonyl sulfide (OCS) and carbon disulfide (CS2) in the Peruvian upwelling regime

NASA Astrophysics Data System (ADS)

Lennartz, Sinikka; von Hobe, Marc; Booge, Dennis; Gonçalves-Araujo, Rafael; Bracher, Astrid; Röttgers, Rüdiger; Ksionzek, Kerstin B.; Koch, Boris P.; Fischer, Tim; Bittig, Henry; Quack, Birgit; Krüger, Kirstin; Marandino, Christa A.

2017-04-01

The ocean is a major source for the climate relevant trace gases carbonyl sulfide (OCS) and carbon disulfide (CS2). While the greenhouse gas CS2 quickly oxidizes to OCS in the atmosphere, the atmospheric lifetime of OCS of 2-7 years leads to an accumulation of this gas and makes it the most abundant reduced sulfur compound in the atmosphere. OCS has a counteracting effect on the climate: in the troposphere, it acts as a greenhouse gas causing warming, whereas it also sustains the stratospheric aerosol layer, and thus increases Earth's albedo causing cooling. To better constrain the important oceanic source of these trace gases, the marine cycling needs to be well understood and quantified. For OCS, the production and consumption processes are identified, but photoproduction and light-independent production rates remain to be quantified across different regions. In contrast, the processes that influence the oceanic cycling of CS2 are less well understood. Here we present new data from a cruise to the Peruvian upwelling regime and relate measurements of OCS and CS2 to key parameters, such as dissolved organic sulfur, chromophoric and fluorescent dissolved organic matter. We use a 1D water column model to further constrain their production and degradation rates. A focus is set on the influence of oxygen on the marine cycling of these two gases in oxygen depleted zones in the ocean, which are expected to expand in the future.

Observations of tropospheric trace gases from GOSAT thermal infrared spectra

NASA Astrophysics Data System (ADS)

Ohyama, Hirofumi; Shiomi, Kei; Kawakami, Shuji; Nakajima, Masakatsu; Maki, Takashi; Deushi, Makoto

2013-04-01

Thermal And Near infrared Sensor for carbon Observation-Fourier Transform Spectrometer (TANSO-FTS), which is one of the sensors onboard the Greenhouse gases Observing SATellite (GOSAT), measures the sunlight backscattered by the Earth's surface and atmosphere as well as the thermal radiance emitted from the Earth. Atmospheric trace gases such as ozone (O3), water vapor (H2O and HDO), methanol (CH3OH) and ammonia (NH3) are derived from the thermal infrared spectral radiance recorded with the TANSO-FTS by an optimal estimation retrieval approach. TANSO-FTS total ozone columns are compared with Dobson spectrophotometer and Ozone Monitoring Instrument (OMI) data. The TANSO-FTS total ozone retrievals exhibit a positive bias of 3-4% with a root-mean-square difference of 2-6% compared to the Dobson and OMI measurements. We compare TANSO-FTS tropospheric ozone columns to those from ozonesonde data as well as from a three-dimensional chemical-climate model (MRI-CCM2). The TANSO-FTS data have high correlations with the ozonesonde data. The seasonal trends of the retrieved tropospheric ozone are consistent with those of the ozonesonde data. The spatial distribution of the tropospheric ozone from the TANSO-FTS and MRI-CCM2 shows good agreement, especially in the high-level tropospheric ozone regions. We also retrieve tropospheric H2O and HDO profiles simultaneously, accounting for the cross correlations between the water isotopes. The joint retrieval results in precise estimation of the isotope ratio by partial cancellation of systematic errors common to both H2O and HDO. The retrieved profiles and columns are compared with radiosonde, GPS, and ground-based high-resolution FTS data. The temporal and spatial variations of the precipitable water and the isotope ratio are consistent with those of the validation data. Finally, air pollutants such as CH3OH and NH3 are retrieved using the retrieved ozone and water vapor. We present the latitudinal and seasonal variations of CH3OH

Horizonal and Vertical Spatial Patterns of Radon and Other Soil-gases Across the El Pilar Fault Trace at Guaraphiche, Edo. Surce (Venezuela)

NASA Astrophysics Data System (ADS)

LaBrecque, J. J.

2002-05-01

Soil-gases (radon, thoron, carbon dioxide and hydrogen) were measured at 63-cm depths along a transect perpendicular to the rupture (fault trace) from the 1997 Caricao earthquake (Mw=6.9) at Guarapiche, state of Sucre (Venezuela). The transect was about 40 meters long with ten sampling points with the spacings was smaller near the rupture. The shapes of the horizontal spatial patterns for radon (Rn-222), thoron (Rn-220) and total radon (Rn-222+Rn-220) were similar; the gas concentrations increased from both ends of the transect toward the rupture where a dip (valley) occurred. Both carbon dioxide and hydrogen gases showed anomalous values at the same sampling points. Twin peaks (anomalies) had been previously reported and suggested that they were due to blockage in the rupture. We have also determined soil-gases from 25-cm to 155-cm depths near the rupture and at the ends of the transect. The results showed that the soil-gas concentrations were not only higher in the upper levels (less than 65-cm) near the fault trace but were similar or greater than the lower levels. Thus, producing the twin peaks when soil-gas sampling was performed at the 65-cm depth. When the sampling was performed at only 45-cm depth the dip over the rupture was much less and the patterns looked more like a broad doublet peak. In conclusion, one can clearly see that not only positive soil-gas anomalies can occur over a fault trace but also negative ones too. 1) This work was partially funded by a research contract from the Venezuelan National Science Foundation (CONICIT Proyecto S1-95000448). 2) Mailing Address: Centro de Quimica, 8424 NW 56th Street, Suite 00204,Miami, Fl 33166 (USA). E-mail jjlabrec@ivic.ve FAX: +58-212-504-1214

Towards uncertainty estimates in global operational forecasts of trace gases in the Copernicus Atmosphere Monitoring System

NASA Astrophysics Data System (ADS)

Huijnen, V.; Bouarar, I.; Chabrillat, S. H.; Christophe, Y.; Thierno, D.; Karydis, V.; Marecal, V.; Pozzer, A.; Flemming, J.

2017-12-01

Operational atmospheric composition analyses and forecasts such as developed in the Copernicus Atmosphere Monitoring Service (CAMS) rely on modules describing emissions, chemical conversion, transport and removal processing, as well as data assimilation methods. The CAMS forecasts can be used to drive regional air quality models across the world. Critical analyses of uncertainties in any of these processes are continuously needed to advance the quality of such systems on a global scale, ranging from the surface up to the stratosphere. With regard to the atmospheric chemistry to describe the fate of trace gases, the operational system currently relies on a modified version of the CB05 chemistry scheme for the troposphere combined with the Cariolle scheme to describe stratospheric ozone, as integrated in ECMWF's Integrated Forecasting System (IFS). It is further constrained by assimilation of satellite observations of CO, O3 and NO2. As part of CAMS we have recently developed three fully independent schemes to describe the chemical conversion throughout the atmosphere. These parameterizations originate from parent model codes in MOZART, MOCAGE and a combination of TM5/BASCOE. In this contribution we evaluate the correspondence and elemental differences in the performance of the three schemes in an otherwise identical model configuration (excluding data-assimilation) against a large range of in-situ and satellite-based observations of ozone, CO, VOC's and chlorine-containing trace gases for both troposphere and stratosphere. This analysis aims to provide a measure of model uncertainty in the operational system for tracers that are not, or poorly, constrained by data assimilation. It aims also to provide guidance on the directions for further model improvement with regard to the chemical conversion module.

Ultrasensitive detection of atmospheric trace gases using frequency modulation spectroscopy

NASA Technical Reports Server (NTRS)

Cooper, David E.

1986-01-01

Frequency modulation (FM) spectroscopy is a new technique that promises to significantly extend the state-of-the-art in point detection of atmospheric trace gases. FM spectroscopy is essentially a balanced bridge optical heterodyne approach in which a small optical absorption or dispersion from an atomic or molecular species of interest generates an easily detected radio frequency (RF) signal. This signal can be monitored using standard RF signal processing techniques and is, in principle, limited only by the shot noise generated in the photodetector by the laser source employed. The use of very high modulation frequencies which exceed the spectral width of the probed absorption line distinguishes this technique from the well-known derivative spectroscopy which makes use of low (kHz) modulation frequencies. FM spectroscopy was recently extended to the 10 micron infrared (IR) spectral region where numerous polyatomic molecules exhibit characteristic vibrational-rotational bands. In conjunction with tunable semiconductor diode lasers, the quantum-noise-limited sensitivity of the technique should allow for the detection of absorptions as small as .00000001 in the IR spectral region. This sensitivity would allow for the detection of H2O2 at concentrations as low as 1 pptv with an integration time of 10 seconds.

Validation of Global Climatologies of Trace Gases Using NASA Global Tropospheric Experiment (GTE) Data

NASA Technical Reports Server (NTRS)

Courchaine, Brian; Venable, Jessica C.

1995-01-01

Methane is an important trace gas because it is a greenhouse gas that affects the oxidative capacity of the atmosphere. It is produced from biological and anthropogenic sources, and is increasing globally at a rate of approximately 0.6% per year [Climate Change 1992, IPCC]. By using National Oceanic and Atmospheric Administration/Climate Monitoring and Diagnostics Laboratory (NOAA/CMDL) ground station data, a global climatology of methane values was produced. Unfortunately, because the NOAA/CMDL ground stations are so sparse, the global climatology is low resolution. In order to compensate for this low resolution data, it was compared to in-situ flight data obtained from the NASA Global Tropospheric Experiment (GTE). The smoothed ground station data correlated well with the flight data. Thus, for the first time it is shown that the smoothing process used to make global contours of methane using the ground stations is a plausible way to approximate global atmospheric concentrations of the gas. These verified climatologies can be used for testing large-scale models of chemical production, destruction, and transport. This project develops the groundwork for further research in building global climatologies from sparse ground station data and studying the transport and distribution of trace gases.

[Trace analysis of aristolochic acid A].

PubMed

Liu, Yalin; Gao, Huimin; Wang, Zhimin; Zhang, Qiwei

2010-12-01

A HPLC method for limit detection of aristolochic acid A in the Chinese herbs containing aristolochic acid or suspected-containing aristolochic acid and their preparations was established. The samples were analyzed on an Alltima C18 column eluted with methanol-water-acetic acid (68:32:1.5) as the mobile phase. Flow rate was at 1.0 mL x min(-1) and the detection wavelength was at 390 nm. The calibration curve was linear over the range from 0.016 to 0.51 g (r = 0.9993) and LOD was 4 ng. The average recovery was 101.2% with RSD of 2.01%. The procedures of sample preparation were systematically investigated. The contents of aristolochic acid A in Radix et Rhizoma Asari bought from market or drugstore were fluctuated from 3.1 to 26.6 microg x g(-1) and 3 of 11 samples accorded with the quality requirement of current Chinese Pharmacopoeia. Among 15 batches samples of Chinese medicaments, only one sample was found to contain aristolochic acid A. The present investigation shows that the method is sensitive and repeatable and it could be used for the limit detection of aristolochic acid A in the Chinese herbal medicines containing trace amount of aristolochic acid A or suspected-containing aristolochic acid A and their preparations.

Measurements of Long-Lived Trace Gases from Commercial Aircraft Platforms: Development of Instrumentation

NASA Technical Reports Server (NTRS)

2002-01-01

The upper troposphere (6-12 km altitude) is a poorly understood and highly vulnerable region of the atmosphere. It is important because many trace species, including ozone, have their greatest impact as greenhouse (infrared-absorbing) gases in this region. The addition of relatively small amounts of anthropogenic chemicals, such as nitrogen oxides, can have a dramatic effect on the abundance of ozone. Some of these pollutants are deposited directly, e.g., by aircraft, while others are transported in. The primary goal of this project was to measure several chemical compounds in the upper troposphere that will help us to understand how air is to transported to that part of the atmosphere; that is, does it come down from the stratosphere, does it rise from the surface via convection, and so on. To obtain adequate sampling to accomplish this goal, we proposed to make measurements from revenue aircraft during normal flight operations.

Dating of young groundwater using four anthropogenic trace gases (SF6, SF5CF3, CFC-12 and Halon-1301): methodology and first results.

PubMed

Bartyzel, Jakub; Rozanski, Kazimierz

2016-01-01

A dedicated, GC-based analytical system is presented which allows detection of four anthropogenic trace gases (SF6, SF5CF3, CFC-12 and Halon-1301) in a single water sample, with detection limits and measurement uncertainties sufficiently low to employ them as quantitative indicators of groundwater age. The gases dissolved in water are extracted in the field using the method based on a dynamic head-space concept. In the laboratory, the investigated gases are cryogenically enriched, separated and measured using an electron capture detector. Reproducibility of the analyses is in the order of 2-5 %. The investigated tracers were measured in several production wells located in the recharge area of an intensively exploited aquifer in southern Poland. While the piston-flow ages of groundwater in the investigated wells revealed internal consistency, they appeared to be generally smaller than the ages derived from time series of tritium content in those wells, interpreted by lumped-parameter models. This difference stems mainly from significantly longer travel times of tritium through the unsaturated zone, when compared to the gaseous tracers being used. The results of this study highlight the benefits of using multiple tracing in quantifying timescales of groundwater flow in shallow aquifer systems.

Adsorption of humic acids and trace metals in natural waters

NASA Technical Reports Server (NTRS)

Leung, W. H.

1982-01-01

Studies concerning the interactions between suspended hydrous iron oxide and dissolved humic acids and trace metals are reported. As a major component of dissolved organic matters and its readiness for adsorption at the solid/water interface, humic acids may play a very important role in the organometallic geochemistry of suspended sediments and in determining the fate and distribution of trace metals, pesticides and anions in natural water systems. Most of the solid phases in natural waters contain oxides and hydroxides. The most simple promising theory to describe the interactions of hydrous iron oxide interface is the surface complex formation model. In this model, the adsorptions of humic acids on hydrous iron oxide may be interpreted as complex formation of the organic bases (humic acid oxyanions) with surface Fe ions. Measurements on adsorptions were made in both fresh water and seawater. Attempts have been made to fit our data to Langmuir adsorption isotherm. Adsorption equilibrium constants were determined.

Metagenomic evidence for metabolism of trace atmospheric gases by high-elevation desert Actinobacteria

PubMed Central

Lynch, Ryan C.; Darcy, John L.; Kane, Nolan C.; Nemergut, Diana R.; Schmidt, Steve K.

2014-01-01

Previous surveys of very dry Atacama Desert mineral soils have consistently revealed sparse communities of non-photosynthetic microbes. The functional nature of these microorganisms remains debatable given the harshness of the environment and low levels of biomass and diversity. The aim of this study was to gain an understanding of the phylogenetic community structure and metabolic potential of a low-diversity mineral soil metagenome that was collected from a high-elevation Atacama Desert volcano debris field. We pooled DNA extractions from over 15 g of volcanic material, and using whole genome shotgun sequencing, observed only 75–78 total 16S rRNA gene OTUs3%. The phylogenetic structure of this community is significantly under dispersed, with actinobacterial lineages making up 97.9–98.6% of the 16S rRNA genes, suggesting a high degree of environmental selection. Due to this low diversity and uneven community composition, we assembled and analyzed the metabolic pathways of the most abundant genome, a Pseudonocardia sp. (56–72% of total 16S genes). Our assembly and binning efforts yielded almost 4.9 Mb of Pseudonocardia sp. contigs, which accounts for an estimated 99.3% of its non-repetitive genomic content. This genome contains a limited array of carbohydrate catabolic pathways, but encodes for CO2 fixation via the Calvin cycle. The genome also encodes complete pathways for the catabolism of various trace gases (H2, CO and several organic C1 compounds) and the assimilation of ammonia and nitrate. We compared genomic content among related Pseudonocardia spp. and estimated rates of non-synonymous and synonymous nucleic acid substitutions between protein coding homologs. Collectively, these comparative analyses suggest that the community structure and various functional genes have undergone strong selection in the nutrient poor desert mineral soils and high-elevation atmospheric conditions. PMID:25566214

40 CFR 60.54a - Standard for municipal waste combustor acid gases.

Code of Federal Regulations, 2014 CFR

2014-07-01

... for Municipal Waste Combustors for Which Construction Is Commenced After December 20, 1989 and On or Before September 20, 1994 § 60.54a Standard for municipal waste combustor acid gases. (a)-(b) [Reserved... 40 Protection of Environment 7 2014-07-01 2014-07-01 false Standard for municipal waste combustor...

Biomass burning and the production of greenhouse gases

NASA Technical Reports Server (NTRS)

Levine, Joel S.

1991-01-01

The present discussion of related aspects of biomass burning describes a technique for estimating the instantaneous emission of trace gases generated by such fires on the basis of satellite imagery, and notes that burning results in significantly enhanced biogenic emissions of N2O, NO, and CH4. Biomass burning therefore has both immediate and long-term impacts on the trace-gas content of the atmosphere. The effects of Kuwait's oil fires, which encompass both combustion gases and particulates, are compared with those of the more general problem.

Community Radiative Transfer Model Applications - A Study of the Retrieval of Trace Gases in the Atmosphere from Cross-track Infrared Sounder (CrIS) Data of a Full-spectral Resolution

NASA Astrophysics Data System (ADS)

Liu, Q.; Nalli, N. R.; Tan, C.; Zhang, K.; Iturbide, F.; Wilson, M.; Zhou, L.

2015-12-01

The Community Radiative Transfer Model (CRTM) [3] operationally supports satellite radiance assimilation for weather forecasting, sensor data verification, and the retrievals of satellite products. The CRTM has been applied to UV and visible sensors, infrared and microwave sensors. The paper will demonstrate the applications of the CRTM, in particular radiative transfer in the retrieva algorithm. The NOAA Unique CrIS/ATMS Processing System (NUCAPS) operationally generates vertical profiles of atmospheric temperature (AVTP) and moisture (AVMP) from Suomi NPP Cross-track Infrared Sounder (CrIS) and Advanced Technology Microwave Sounder (ATMS) measurements. Current operational CrIS data have reduced spectral resolution: 1.25 cm-1 for a middle wave band and 2.5 cm-1 for a short-wave wave band [1]. The reduced spectral data largely degraded the retrieval accuracy of trace gases. CrIS full spectral data are also available now which have single spectral resolution of 0.625 cm-1 for all of the three bands: long-wave band, middle wave band, and short-wave band. The CrIS full-spectral resolution data is critical to the retrieval of trace gases such as O3, CO [2], CO2, and CH4. In this paper, we use the Community Radiative Transfer Model (CRTM) to study the impact of the CrIS spectral resolution on the retrieval accuracy of trace gases. The newly released CRTM version 2.2.1 can simulates Hamming-apodized CrIS radiance of a full-spectral resolution. We developed a small utility that can convert the CRTM simulated radiance to un-apodized radiance. The latter has better spectral information which can be helpful to the retrievals of the trace gases. The retrievals will be validated using both NWP model data as well as the data collected during AEROSE expeditions [4]. We will also discuss the sensitivity on trace gases between apodized and un-apodized radiances. References[1] Gambacorta, A., et al.(2013), IEEE Lett., 11(9), doi:10.1109/LGRS.2014.230364, 1639-1643. [2] Han, Y., et

Transport of Asian Aerosols and Trace Gases to North America During the INTEX-B Field Campaign: A Regional Chemical Transport Model Analysis.

NASA Astrophysics Data System (ADS)

Adhikary, B.; Kulkarni, S.; Carmichael, G. R.; Tang, Y.; Dallura, A.; Mena, M.; Streets, D.; Zhang, Q.

2007-12-01

The Intercontinental Chemical Transport Experiment-Phase B (INTEX-B) was conducted over the Pacific Ocean during the 2006 North American spring season. One of the scientific objectives of the INTEX-B field campaign was to quantify the transport and chemical evolution/aging of Asian air pollution into North America. The field campaign deployed multiple experimental platforms such as satellites, aircrafts and surface measurements stations to study the pollution outflow to North America. Three dimensional chemical transport models were used to provide chemical weather forecasts and assist in flight planning during the mission. The Sulfur Transport and dEposition Model (STEM) is a regional chemical transport model developed at the University of Iowa. The STEM model was involved in providing chemical weather forecasts and assist in flight planning during the INTEX-B intensive field campaign. In this study we will report the STEM model performance of aerosols and trace gases in its ability to capture the pollutant plume with experimental observations obtained from the field campaign. The study will then relate the emissions of trace gases and aerosols to atmospheric composition, sources and sinks using the newly developed emissions inventory for the INTEX-B field campaign.

Organic acids and selected nitrogen species for ABLE-3

NASA Technical Reports Server (NTRS)

Talbot, Robert W.

1991-01-01

The NASA Global Tropospheric Experiment (GTE) executed airborne science missions aboard the NASA Wallops Electra (NA429) in the North American high latitude (greater than 45 deg North) atmosphere during Jul. to Aug. 1988 and Jul. to Aug. 1990. These missions were part of GTE's Atmospheric Boundary Layer Experiment (ABLE). The 1988 mission , ABLE-3A, examined the ecosystems of Alaska as a source and/or sink for important tropospheric gases and particles, and gained new information on the chemical composition of the Arctic atmosphere during the summertime. During 1990 the second high latitude mission, ABLE-3B, focused on the Hudson Bay Lowland and Labrador regions of Canada. Both of these missions provided benchmark data sets on atmosphere biosphere exchange and atmospheric chemistry over largely uninhabited regions of North America. In support of the GTE/ABLE-3A and -3B field missions, the University of New Hampshire flew instrumentation aboard the Wallops Electra research aircraft to provide measurements of the trace gases nitric (HNO3), formic (HCOOH), and acetic (CH3COOH) acid. In addition, measurements were conducted to determine the major water soluble ionic composition of the atmospheric aerosol. For ABLE-3B, groundbased measurements of the acidic trace gases were also performed from the NASA micrometerological tower situated at Schefferville, Laborador. These measurements were aimed at assessing dry deposition of acidic gases to the taiga ecosystem in the Laborador region of Canada.

Using the full IASI spectrum for the physical retrieval of temperature, H2O, HDO, O3, minor and trace gases

NASA Astrophysics Data System (ADS)

Serio, C.; Blasi, M. G.; Liuzzi, G.; Masiello, G.; Venafra, S.

2017-02-01

IASI (Infrared Atmospheric Sounder Interferometer) is flying on the European MetOp series of weather satellites. Besides acquiring temperature and humidity data, IASI also observes the infrared emission of the main minor and trace atmospheric components with high precision. The retrieval of these gases would be highly beneficial to the efforts of scientists monitoring Earths climate. IASI retrieval capability and algorithms have been mostly driven by Numerical Weather Prediction centers, whose limited resources for data transmission and computing is hampering the full exploitation of IASI information content. The quest for real or nearly real time processing has affected the precision of the estimation of minor and trace gases, which are normally retrieved on a very coarse spatial grid. The paper presents the very first retrieval of the complete suite of IASI target parameters by exploiting all its 8461 channels. The analysis has been exemplified for sea surface and the target parameters will include sea surface temperature, temperature profile, water vapour and HDO profiles, ozone profile, total column amount of CO, CO2, CH4, N2O, SO2, HNO3, NH3, OCS and CF4. Concerning CO2, CH4 and N2O, it will be shown that their colum amount can be obtained for each single IASI IFOV (Instantaneous Field of View) with a precision better than 1-2%, which opens the possibility to analyze, e.g., the formation of regional patterns of greenhouse gases. To assess the quality of the retrieval, a case study has been set up which considers two years of IASI soundings over the Hawaii, Manua Loa validation station.

Field measurements of trace gases and aerosols emitted by peat fires in Central Kalimantan, Indonesia, during the 2015 El Niño

NASA Astrophysics Data System (ADS)

Stockwell, Chelsea E.; Jayarathne, Thilina; Cochrane, Mark A.; Ryan, Kevin C.; Putra, Erianto I.; Saharjo, Bambang H.; Nurhayati, Ati D.; Albar, Israr; Blake, Donald R.; Simpson, Isobel J.; Stone, Elizabeth A.; Yokelson, Robert J.

2016-09-01

Peat fires in Southeast Asia have become a major annual source of trace gases and particles to the regional-global atmosphere. The assessment of their influence on atmospheric chemistry, climate, air quality, and health has been uncertain partly due to a lack of field measurements of the smoke characteristics. During the strong 2015 El Niño event we deployed a mobile smoke sampling team in the Indonesian province of Central Kalimantan on the island of Borneo and made the first, or rare, field measurements of trace gases, aerosol optical properties, and aerosol mass emissions for authentic peat fires burning at various depths in different peat types. This paper reports the trace gas and aerosol measurements obtained by Fourier transform infrared spectroscopy, whole air sampling, photoacoustic extinctiometers (405 and 870 nm), and a small subset of the data from analyses of particulate filters. The trace gas measurements provide emission factors (EFs; grams of a compound per kilogram biomass burned) for up to ˜ 90 gases, including CO2, CO, CH4, non-methane hydrocarbons up to C10, 15 oxygenated organic compounds, NH3, HCN, NOx, OCS, HCl, etc. The modified combustion efficiency (MCE) of the smoke sources ranged from 0.693 to 0.835 with an average of 0.772 ± 0.053 (n = 35), indicating essentially pure smoldering combustion, and the emissions were not initially strongly lofted. The major trace gas emissions by mass (EF as g kg-1) were carbon dioxide (1564 ± 77), carbon monoxide (291 ± 49), methane (9.51 ± 4.74), hydrogen cyanide (5.75 ± 1.60), acetic acid (3.89 ± 1.65), ammonia (2.86 ± 1.00), methanol (2.14 ± 1.22), ethane (1.52 ± 0.66), dihydrogen (1.22 ± 1.01), propylene (1.07 ± 0.53), propane (0.989 ± 0.644), ethylene (0.961 ± 0.528), benzene (0.954 ± 0.394), formaldehyde (0.867 ± 0.479), hydroxyacetone (0.860 ± 0.433), furan (0.772 ± 0.035), acetaldehyde (0.697 ± 0.460), and acetone (0.691 ± 0.356). These field data support significant revision

Trace element geochemistry of volcanic gases and particles from 1983--1984 eruptive episodes of Kilauea volcano

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

Crowe, B.M.; Finnegan, D.L.; Zoller, W.H.

1987-12-10

Compositional data have been obtained for volcanic gases and particles collected from fume emitted at the Pu'u O'o vent on the east rift zone of Kilauea volcano. The samples were collected by pumping fume through a filter pack system consisting of a front stage particulate filter followed by four base-treated filters (/sup 7/LiOH). Particles and condensed phases are trapped on the particulate filter, and acidic gases are collected on the treated filters. The filters are analyzed for 30 elements by instrumental neutron activation analysis. Fume samples were collected from the Pu'u O'o vent for two eruptive episodes: (1) 7 daysmore » after episode 11 (cooling vent samples) and (2) the stage of episode 13 (active vent samples).« less

Average rainwater pH, concepts of atmospheric acidity, and buffering in open systems

NASA Astrophysics Data System (ADS)

Liljestrand, Howard M.

The system of water equilibrated with a constant partial pressure of CO 2, as a reference point for pH acidity-alkalinity relationships, has nonvolatile acidity and alkalinity components as conservative quantities, but not [H +]. Simple algorithms are presented for the determination of the average pH for combinations of samples both above and below pH 5.6. Averaging the nonconservative quantity [H +] yields erroneously low mean pH values. To extend the open CO 2 system to include other volatile atmospheric acids and bases distributed among the gas, liquid and particulate matter phases, a theoretical framework for atmospheric acidity is presented. Within certain oxidation-reduction limitations, the total atmospheric acidity (but not free acidity) is a conservative quantity. The concept of atmospheric acidity is applied to air-water systems approximating aerosols, fogwater, cloudwater and rainwater. The buffer intensity in hydrometeors is described as a function of net strong acidity, partial pressures of acid and base gases and the water to air ratio. For high liquid to air volume ratios, the equilibrium partial pressures of trace acid and base gases are set by the pH or net acidity controlled by the nonvolatile acid and base concentrations. For low water to air volume ratios as well as stationary state systems such as precipitation scavenging with continuous emissions, the partial pressures of trace gases (NH 3, HCl, HNO 3, SO 2 and CH 3COOH) appear to be of greater or equal importance as carbonate species as buffers in the aqueous phase.

Impact of Convection and Long Range Transport on Short-Lived Trace Gases in the UT/LS

NASA Astrophysics Data System (ADS)

Atlas, E. L.; Schauffler, S.; Navarro, M. A.; Lueb, R.; Hendershot, R.; Ueyama, R.

2017-12-01

Chemical composition of the air in the upper troposphere/lower stratosphere is controlled by a balance of transport, photochemistry, and physical processes, such as interactions with clouds, ice, and aerosol. The chemistry of the air masses that reach the upper troposphere can potentially have profound impacts on the chemistry in the near tropopause region. For example, the transport of reactive organic halogens and their transformation to inorganic halogen species, e.g., Br, BrO, etc., can have a significant impact on ozone budgets in this region and even deeper the stratosphere. Trace gas measurements in the region near the tropopause can also indicate potential sources of surface emissions that are transported to high altitudes. Measurement of trace gases, including such compounds as non-methane hydrocarbons, hydrochlorofluorocarbons, halogenated solvents, methyl halides, etc., can be used to characterize source emissions from industrial, urban, biomass burning, or marine origins. Recent airborne research campaigns have been conducted to better characterize the chemical composition and variations in the UT/LS region. This presentation will discuss these measurements, with a special emphasis on the role of convection and transport in modifying the chemical composition of the UT/LS.

Biological production of acetic acid from waste gases with Clostridium ljungdahlii

DOEpatents

Gaddy, James L.

1998-01-01

A method and apparatus for converting waste gases from industrial processes such as oil refining, carbon black, coke, ammonia, and methanol production, into useful products. The method includes introducing the waste gases into a bioreactor where they are fermented to various organic acids or alcohols by anaerobic bacteria within the bioreactor. These valuable end products are then recovered, separated and purified. In an exemplary recovery process, the bioreactor raffinate is passed through an extraction chamber into which one or more non-inhibitory solvents are simultaneously introduced to extract the product. Then, the product is separated from the solvent by distillation. Gas conversion rates can be maximized by use of centrifuges, hollow fiber membranes, or other means of ultrafiltration to return entrained anaerobic bacteria from the bioreactor raffinate to the bioreactor itself, thus insuring the highest possible cell concentration.

Biological production of acetic acid from waste gases with Clostridium ljungdahlii

DOEpatents

Gaddy, J.L.

1998-09-15

A method and apparatus are disclosed for converting waste gases from industrial processes such as oil refining, carbon black, coke, ammonia, and methanol production, into useful products. The method includes introducing the waste gases into a bioreactor where they are fermented to various organic acids or alcohols by anaerobic bacteria within the bioreactor. These valuable end products are then recovered, separated and purified. In an exemplary recovery process, the bioreactor raffinate is passed through an extraction chamber into which one or more non-inhibitory solvents are simultaneously introduced to extract the product. Then, the product is separated from the solvent by distillation. Gas conversion rates can be maximized by use of centrifuges, hollow fiber membranes, or other means of ultrafiltration to return entrained anaerobic bacteria from the bioreactor raffinate to the bioreactor itself, thus insuring the highest possible cell concentration. 5 figs.

Nighttime chemical evolution of aerosol and trace gases in a power plant plume: Implications for secondary organic nitrate and organosulfate aerosol formation, NO3 radical chemistry, and N2O5 heterogeneous hydrolysis

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

Zaveri, R.A.; Kleinman, L.; Berkowitz, C. M.

2010-06-01

Nighttime chemical evolution of aerosol and trace gases in a coal-fired power plant plume was monitored with the Department of Energy Grumman Gulfstream-1 aircraft during the 2002 New England Air Quality Study field campaign. Quasi-Lagrangian sampling in the plume at increasing downwind distances and processing times was guided by a constant-volume balloon that was released near the power plant at sunset. While no evidence of fly ash particles was found, concentrations of particulate organics, sulfate, and nitrate were higher in the plume than in the background air. The enhanced sulfate concentrations were attributed to direct emissions of gaseous H{sub 2}SO{submore » 4}, some of which had formed new particles as evidenced by enhanced concentrations of nucleation-mode particles in the plume. The aerosol species were internally mixed and the particles were acidic, suggesting that particulate nitrate was in the form of organic nitrate. The enhanced particulate organic and nitrate masses in the plume were inferred as secondary organic aerosol, which was possibly formed from NO{sub 3} radical-initiated oxidation of isoprene and other trace organic gases in the presence of acidic sulfate particles. Microspectroscopic analysis of particle samples suggested that some sulfate was in the form of organosulfates. Microspectroscopy also revealed the presence of sp{sup 2} hybridized C = C bonds, which decreased with increasing processing time in the plume, possibly because of heterogeneous chemistry on particulate organics. Constrained plume modeling analysis of the aircraft and tetroon observations showed that heterogeneous hydrolysis of N{sub 2}O{sub 5} was negligibly slow. These results have significant implications for several issues related to the impacts of power plant emissions on air quality and climate.« less

Measurements of Acidic Gases and Aerosol Species Aboard the NASA DC-8 Aircraft During the Pacific Exploratory Mission in the Tropics (PEM-Tropics A)

NASA Technical Reports Server (NTRS)

Talbot, Robert W.; Dibb, Jack E.

1999-01-01

We received funding to provide measurements of nitric acid (HNO3), formic acid (HCOOH), acetic acid (CH3COOH), and the chemical composition of aerosols aboard the NASA Ames DC-8 research aircraft during the PEM-Tropics A mission. These measurements were successfully completed and the final data resides in the electronic archive (ftp-gte.larc.nasa.gov) at NASA Langley Research Center. For the PEM-Tropics A mission the University of New Hampshire group was first author of four different manuscripts. Three of these have now appeared in the Journal of Geophysical Research-Atmospheres, included in the two section sections on PEM-Tropics A. The fourth manuscript has just recently been submitted to this same journal as a stand alone paper. All four of these papers are included in this report. The first paper (Influence of biomass combustion emissions on the distribution of acidic trace gases over the Southern Pacific basin during austral springtime) describes the large-scale distributions of HNO3, HCOOH, and CH3COOH. Arguments were presented to show, particularly in the middle tropospheric region, that biomass burning emissions from South America and Africa were a major source of acidic gases over the South Pacific basin. The second paper (Aerosol chemical composition and distribution during the Pacific Exploratory Mission (PEM) Tropics) covers the aerosol aspects of our measurement package. Compared to acidic gases, O3, and selected hydrocarbons, the aerosol chemistry showed little influence from biomass burning emissions. The data collected in the marine boundary layer showed a possible marine source of NH3 to the troposphere in equatorial areas. This source had been speculated on previously, but our data was the first collected from an airborne platform to show its large-scale features. The third paper (Constraints on the age and dilution of Pacific Exploratory Mission-Tropics biomass burning plumes from the natural radionuclide tracer Pb-210) utilized the unexpectedly

Seasonal and spatial changes in trace gases over megacities from Aura TES observations: two case studies

NASA Astrophysics Data System (ADS)

Cady-Pereira, Karen E.; Payne, Vivienne H.; Neu, Jessica L.; Bowman, Kevin W.; Miyazaki, Kazuyuki; Marais, Eloise A.; Kulawik, Susan; Tzompa-Sosa, Zitely A.; Hegarty, Jennifer D.

2017-08-01

The Aura Tropospheric Emission Spectrometer (TES) is collecting closely spaced observations over 19 megacities. The objective is to obtain measurements that will lead to better understanding of the processes affecting air quality in and around these cities, and to better estimates of the seasonal and interannual variability. We explore the TES measurements of ozone, ammonia, methanol and formic acid collected around the Mexico City metropolitan area (MCMA) and in the vicinity of Lagos (Nigeria). The TES data exhibit seasonal signals that are correlated with Atmospheric Infrared Sounder (AIRS) CO and Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD), with in situ measurements in the MCMA and with Goddard Earth Observing System (GEOS)-Chem model output in the Lagos area. TES was able to detect an extreme pollution event in the MCMA on 9 April 2013, which is also evident in the in situ data. TES data also show that biomass burning has a greater impact south of the city than in the caldera where Mexico City is located. TES measured enhanced values of the four species over the Gulf of Guinea south of Lagos. Since it observes many cities from the same platform with the same instrument and applies the same retrieval algorithms, TES data provide a very useful tool for easily comparing air quality measures of two or more cities. We compare the data from the MCMA and Lagos, and show that, while the MCMA has occasional extreme pollution events, Lagos consistently has higher levels of these trace gases.

Trace Gases and Aerosol Optical Properties Over the US Mid-Atlantic During Summer 2001

NASA Astrophysics Data System (ADS)

Doddridge, B. G.; Piety, C. A.

2001-12-01

Anthropogenic emissions from rapid urban sprawl, commuter/commercial traffic and industrialization along the East Coast of the United States have a profound effect on urban and regional air quality. During summer 2001 we used a light aircraft research platform operated from North Carolina northward through Pennsylvania measuring meteorological scalars, selected trace gases and aerosol optical properties on selected pollution episode days. The goal of this research is to gain an improved understanding of the sources, sinks, transport and photochemical transformations controlling the observed abundance of photochemical oxidants and fine particulate haze over the U.S. Mid-Atlantic region. The aircraft research capabilities will be described, over 60 research flights totaling in excess of 160 flight hours summarized, and key findings presented. Although westerly transport of remnant ozone and haze along with precursors can make substantial contributions to observed urban corridor air quality aloft, significant production downwind of the urban center often can occur within the planetary boundary layer during the afternoon hours.

Trapping, chemistry, and export of trace gases in the South Asian summer monsoon observed during CARIBIC flights in 2008

NASA Astrophysics Data System (ADS)

Rauthe-Schöch, Armin; Baker, Angela K.; Schuck, Tanja J.; Brenninkmeijer, Carl A. M.; Zahn, Andreas; Hermann, Markus; Stratmann, Greta; Ziereis, Helmut; van Velthoven, Peter F. J.; Lelieveld, Jos

2016-03-01

The CARIBIC (Civil Aircraft for the Regular Investigation of the Atmosphere Based on an Instrument Container) passenger aircraft observatory performed in situ measurements at 10-12 km altitude in the South Asian summer monsoon anticyclone between June and September 2008. These measurements enable us to investigate this atmospheric region (which so far has mostly been observed from satellites) using the broad suite of trace gases and aerosol particles measured by CARIBIC. Elevated levels of a variety of atmospheric pollutants (e.g. carbon monoxide, total reactive nitrogen oxides, aerosol particles, and several volatile organic compounds) were recorded. The measurements provide detailed information about the chemical composition of air in different parts of the monsoon anticyclone, particularly of ozone precursors. While covering a range of 3500 km inside the monsoon anticyclone, CARIBIC observations show remarkable consistency, i.e. with distinct latitudinal patterns of trace gases during the entire monsoon period. Using the CARIBIC trace gas and aerosol particle measurements in combination with the Lagrangian particle dispersion model FLEXPART, we investigated the characteristics of monsoon outflow and the chemical evolution of air masses during transport. The trajectory calculations indicate that these air masses originated mainly from South Asia and mainland Southeast Asia. Estimated photochemical ages of the air were found to agree well with transport times from a source region east of 90-95° E. The photochemical ages of the air in the southern part of the monsoon anticyclone were systematically younger (less than 7 days) and the air masses were mostly in an ozone-forming chemical mode. In its northern part the air masses were older (up to 13 days) and had unclear ozone formation or destruction potential. Based on analysis of forward trajectories, several receptor regions were identified. In addition to predominantly westward transport, we found evidence for

Trapping, chemistry and export of trace gases in the South Asian summer monsoon observed during CARIBIC flights in 2008

NASA Astrophysics Data System (ADS)

Rauthe-Schöch, A.; Baker, A. K.; Schuck, T. J.; Brenninkmeijer, C. A. M.; Zahn, A.; Hermann, M.; Stratmann, G.; Ziereis, H.; van Velthoven, P. F. J.; Lelieveld, J.

2015-03-01

The CARIBIC (Civil Aircraft for the Regular Investigation of the Atmosphere Based on an Instrument Container) passenger aircraft observatory performed in situ measurements at 10-12 km altitude in the South Asian summer monsoon anticyclone between June and September 2008. These measurements enable us to investigate this atmospheric region, which so far has mostly been observed from satellites, using the broad suite of trace gases and aerosols measured by CARIBIC. Elevated levels of a range of atmospheric pollutants were recorded e.g. carbon monoxide, total reactive nitrogen oxides, aerosol particles and several volatile organic compounds. The measurements provide detailed information about the chemical composition of air in different parts of the monsoon anticyclone, particularly of ozone precursors. While covering a range of 3500 km inside the monsoon anticyclone, CARIBIC observations show remarkable consistency, i.e. with regular latitudinal patterns of trace gases during the entire monsoon period. Trajectory calculations indicate that these air masses originated mainly from South Asia and Mainland Southeast Asia. Using the CARIBIC trace gas and aerosol measurements in combination with the Lagrangian particle dispersion model FLEXPART we investigated the characteristics of monsoon outflow and the chemical evolution of air masses during transport. Estimated photochemical ages of the air were found to agree well with transport times from a source region east of 95° E. The photochemical ages of the air in the southern part of the monsoon anticyclone were consistently younger (less than 7 days) and the air masses mostly in an ozone forming chemical regime. In its northern part the air masses were older (up to 13 days) and had unclear ozone formation or destruction potential. Based on analysis of forward trajectories several receptor regions were identified. In addition to predominantly westward transport, we found evidence for efficient transport (within 10 days) to

Dynamics of submarine groundwater discharge and associated fluxes of dissolved nutrients, carbon, and trace gases to the coastal zone (Okatee River estuary, South Carolina)

USGS Publications Warehouse

Porubsky, W.P.; Weston, N.B.; Moore, W.S.; Ruppel, C.; Joye, S.B.

2014-01-01

Multiple techniques, including thermal infrared aerial remote sensing, geophysical and geological data, geochemical characterization and radium isotopes, were used to evaluate the role of groundwater as a source of dissolved nutrients, carbon, and trace gases to the Okatee River estuary, South Carolina. Thermal infrared aerial remote sensing surveys illustrated the presence of multiple submarine groundwater discharge sites in Okatee headwaters. Significant relationships were observed between groundwater geochemical constituents and 226Ra activity in groundwater with higher 226Ra activity correlated to higher concentrations of organics, dissolved inorganic carbon, nutrients, and trace gases to the Okatee system. A system-level radium mass balance confirmed a substantial submarine groundwater discharge contribution of these constituents to the Okatee River. Diffusive benthic flux measurements and potential denitrification rate assays tracked the fate of constituents in creek bank sediments. Diffusive benthic fluxes were substantially lower than calculated radium-based submarine groundwater discharge inputs, showing that advection of groundwater-derived nutrients dominated fluxes in the system. While a considerable potential for denitrification in tidal creek bank sediments was noted, in situ denitrification rates were nitrate-limited, making intertidal sediments an inefficient nitrogen sink in this system. Groundwater geochemical data indicated significant differences in groundwater chemical composition and radium activity ratios between the eastern and western sides of the river; these likely arose from the distinct hydrological regimes observed in each area. Groundwater from the western side of the Okatee headwaters was characterized by higher concentrations of dissolved organic and inorganic carbon, dissolved organic nitrogen, inorganic nutrients and reduced metabolites and trace gases, i.e. methane and nitrous oxide, than groundwater from the eastern side

The airborne Laser Absorption Spectrometer - A new instrument of remote measurement of atmospheric trace gases

NASA Technical Reports Server (NTRS)

Shumate, M. S.; Menzies, R. T.

1978-01-01

The Laser Absorption Spectrometer is a portable instrument developed by JPL for remote measurement of trace gases from an aircraft platform. It contains two carbon dioxide lasers, two optical heterodyne receivers, appropriate optics to aim the lasers at the ground and detect the backscattered energy, and signal processing and recording electronics. Operating in the differential-absorption mode, it is possible to monitor one atmospheric gas at a time and record the data in real time. The system can presently measure ozone, ethylene, water vapor, and chlorofluoromethanes with high sensitivity. Airborne measurements were made in early 1977 from the NASA/JPL twin-engine Beechcraft and in May 1977 from the NASA Convair 990 during the ASSESS-II Shuttle Simulation Study. These flights resulted in measurements of ozone concentrations in the lower troposphere which were compared with ground-based values provided by the Air Pollution Control District. This paper describes the details of the instrument and results of the airborne measurements.

Recent developments in high altitude aircraft sampling - Mount St. Helens and stratospheric trace gases

NASA Astrophysics Data System (ADS)

Leifer, R.; Sommers, K. G.; Guggenheim, S. F.; Fisenne, I.

1981-02-01

An ultra-clean, low volume gas sampling system (CLASS), flown aboard a high altitude aircraft (WB-57F), and providing information on stratospheric trace gases is presented. Attention is given to the instrument design and the electronic control design. Since remote operation is mandatory on the WB-57F, a servo pressure transducer, electrical pressure switch for automatic shutdown, and a mechanical safety relief valve were installed on the sampling manifold, indicated on the CLASS flow chart. The electronic control system consists of hermetically sealed solid state timers, relays, and a stepping switch, for controlling the compressor pump and solenoid valves. In designing the automatic control system, vibration, shock, acceleration, extreme low temperature, and aircraft safety were important considerations. CLASS was tested on three separate occasions, and tables of analytical data from these flights are presented. Readiness capability was demonstrated when the Mount St. Helens eruption plume of May 18, 1980, was intercepted, and it was concluded that no large injection of Rn-222 entered the stratosphere or troposphere from the eruption.

Trace analysis of impurities in bulk gases by gas chromatography-pulsed discharge helium ionization detection with "heart-cutting" technique.

PubMed

Weijun, Yao

2007-10-12

A method has been developed for the detection of low-nL/L-level impurities in bulk gases such as H(2), O(2), Ar, N(2), He, methane, ethylene and propylene, respectively. The solution presented here is based upon gas chromatography-pulsed discharge helium ionization detection (GC-PDHID) coupled with three two-position valves, one two-way solenoid valve and four packed columns. During the operation, the moisture and heavy compounds are first back-flushed via a pre-column. Then the trace impurities (except CO(2) which is diverted to a separate analytical column for separation and detection) together with the matrix enter onto a main column, followed by the heart-cut of the impurities onto a longer analytical column for complete separation. Finally the detection is performed by PDHID. This method has been applied to different bulk gases and the applicability of detecting impurities in H(2), Ar, and N(2) are herewith demonstrated. As an example, the resulting detection limit of 100 nL/L and a dynamic range of 100-1000 nL/L have been obtained using an Ar sample containing methane.

Biological cycling of atmospheric trace gases

NASA Technical Reports Server (NTRS)

Hitchcock, D. R.; Wechsler, A. E.

1972-01-01

A detailed critical review was conducted of present knowledge of the influence of biological processes on the cycling of selected atmospheric gas constituents--methane, carbon monoxide, and gaseous compounds of nitrogen (nitrous oxide, ammonia, nitric oxide, and nitrogen dioxide) and sulfur (hydrogen sulfide and sulfur dioxide). The identification was included of biological and other sources of each gas, a survey of abundance measurements reported in the literature, and a review of the atmospheric fate of each contituent. Information is provided on which to base conclusions regarding the importance of biological processes on the atmospheric distribution and surface-atmosphere exchange of each constituent, and a basis for estimating the adequacy of present knowledge of these factors. A preliminary analysis was conducted of the feasibility of monitoring the biologically influenced temporal and spatial variations in abundance of these gases in the atmosphere from satellites.

Source gases: Concentrations, emissions, and trends

NASA Technical Reports Server (NTRS)

Fraser, Paul J.; Harriss, Robert; Penkett, Stuart A.; Makide, Yoshihiro; Sanhueza, Eugenio; Alyea, Fred N.; Rowland, F. Sherwood; Blake, Don; Sasaki, Toru; Cunnold, Derek M.

1991-01-01

Source gases are defined as those gases that influence levels of stratospheric ozone (O3) by transporting species containing halogen, hydrogen, and nitrogen to the stratosphere. Examples are the CFC's, methane (CH4), and nitrous oxide (N2O). Other source gases that also come under consideration in an atmospheric O3 context are those that are involved in the O3 or hydroxyl (OH) radical chemistry of the troposphere. Examples are CH4, carbon monoxide (CO), and nonmethane hydrocarbons (NMHC's). Most of the source gases, along with carbon dioxide (CO2) and water vapor (H2O), are climatically significant and thus affect stratospheric O3 levels by their influence on stratospheric temperatures. Carbonyl sulphide (COS) could affect stratospheric O3 through maintenance of the stratospheric sulphate aerosol layer, which may be involved in heterogeneous chlorine-catalyzed O3 destruction. The previous reviews of trends and emissions of source gases, either from the context of their influence on atmospheric O3 or global climate change, are updated. The current global abundances and concentration trends of the trace gases are given in tabular format.

Isothermal absorption of soluble gases by atmospheric nanoaerosols

NASA Astrophysics Data System (ADS)

Elperin, T.; Fominykh, A.; Krasovitov, B.; Lushnikov, A.

2013-01-01

We investigate mass transfer during the isothermal absorption of atmospheric trace soluble gases by a single droplet whose size is comparable to the molecular mean free path in air at normal conditions. It is assumed that the trace reactant diffuses to the droplet surface and then reacts with the substances inside the droplet according to the first-order rate law. Our analysis applies a flux-matching theory of transport processes in gases and assumes constant thermophysical properties of the gases and liquids. We derive an integral equation of Volterra type for the transient molecular flux density to a liquid droplet and solve it numerically. Numerical calculations are performed for absorption of sulfur dioxide (SO2), dinitrogen trioxide (N2O3), and chlorine (Cl2) by liquid nanoaerosols accompanied by chemical dissociation reaction. It is shown that during gas absorption by nanoaerosols, the kinetic effects play a significant role, and neglecting kinetic effects leads to a significant overestimation of the soluble gas flux into a droplet during the entire period of gas absorption.

Isothermal absorption of soluble gases by atmospheric nanoaerosols.

PubMed

Elperin, T; Fominykh, A; Krasovitov, B; Lushnikov, A

2013-01-01

We investigate mass transfer during the isothermal absorption of atmospheric trace soluble gases by a single droplet whose size is comparable to the molecular mean free path in air at normal conditions. It is assumed that the trace reactant diffuses to the droplet surface and then reacts with the substances inside the droplet according to the first-order rate law. Our analysis applies a flux-matching theory of transport processes in gases and assumes constant thermophysical properties of the gases and liquids. We derive an integral equation of Volterra type for the transient molecular flux density to a liquid droplet and solve it numerically. Numerical calculations are performed for absorption of sulfur dioxide (SO(2)), dinitrogen trioxide (N(2)O(3)), and chlorine (Cl(2)) by liquid nanoaerosols accompanied by chemical dissociation reaction. It is shown that during gas absorption by nanoaerosols, the kinetic effects play a significant role, and neglecting kinetic effects leads to a significant overestimation of the soluble gas flux into a droplet during the entire period of gas absorption.

Development of 2-D-MAX-DOAS and retrievals of trace gases and aerosols optical properties

NASA Astrophysics Data System (ADS)

Ortega, Ivan

Air pollution is a major problem worldwide that adversely a_ects human health, impacts ecosystems and climate. In the atmosphere, there are hundreds of important compounds participating in complex atmospheric reactions linked to air quality and climate. Aerosols are relevant because they modify the radiation balance, a_ect clouds, and thus Earth albedo. The amount of aerosol is often characterized by the vertical integral through the entire height of the atmosphere of the logarithm fraction of incident light that is extinguished called Aerosol Optical Depth (AOD). The AOD at 550 nm (AOD550) over land is 0.19 (multi annual global mean), and that over oceans is 0.13. About 43 % of the Earth surface shows AOD550 smaller than 0.1. There is a need for measurement techniques that are optimized to measure aerosol optical properties under low AOD conditions, sample spatial scales that resemble satellite ground-pixels and atmospheric models, and help integrate remote sensing and in-situ observations to obtain optical closure on the effects of aerosols and trace gases in our changing environment. In this work, I present the recent development of the University of Colorado two dimensional (2-D) Multi-AXis Differential Optical Absorption Spectroscopy (2-D-MAX-DOAS) instrument to measure the azimuth and altitude distribution of trace gases and aerosol optical properties simultaneously with a single instrument. The instrument measures solar scattered light from any direction in the sky, including direct sun light in the hyperspectral domain. In Chapter 2, I describe the capabilities of 2-D measurements in the context of retrievals of azimuth distributions of nitrogen dioxide (NO2), formaldehyde (HCHO), and glyoxal (CHOCHO), which are precursors for tropospheric O3 and aerosols. The measurements were carried out during the Multi-Axis DOAS Comparison campaign for Aerosols and Trace gases (MAD-CAT) campaign in Mainz, Germany and show the ability to bridge spatial scales to

Method for monitoring stack gases for uranium activity

DOEpatents

Beverly, C.R.; Ernstberger, E.G.

1985-07-03

A method for monitoring the stack gases of a purge cascade of gaseous diffusion plant for uranium activity. A sample stream is taken from the stack gases and contacted with a volume of moisture-laden air for converting trace levels of uranium hexafluoride, if any, in the stack gases into particulate uranyl fluoride. A continuous strip of filter paper from a supply roll is passed through this sampling stream to intercept and gather any uranyl fluoride in the sampling stream. This filter paper is then passed by an alpha scintillation counting device where any radioactivity on the filter paper is sensed so as to provide a continuous monitoring of the gas stream for activity indicative of the uranium content in the stack gases. 1 fig.

Method for monitoring stack gases for uranium activity

DOEpatents

Beverly, Claude R.; Ernstberger, Harold G.

1988-01-01

A method for monitoring the stack gases of a purge cascade of a gaseous diffusion plant for uranium activity. A sample stream is taken from the stack gases and contacted with a volume of moisture-laden air for converting trace levels of uranium hexafluoride, if any, in the stack gases into particulate uranyl fluoride. A continuous strip of filter paper from a supply roll is passed through this sampling stream to intercept and gather any uranyl fluoride in the sampling stream. This filter paper is then passed by an alpha scintillation counting device where any radioactivity on the filter paper is sensed so as to provide a continuous monitoring of the gas stream for activity indicative of the uranium content in the stack gases.

Note: A dual temperature closed loop batch reactor for determining the partitioning of trace gases within CO2-water systems.

PubMed

Warr, Oliver; Rochelle, Christopher A; Masters, Andrew J; Ballentine, Christopher J

2016-01-01

An experimental approach is presented which can be used to determine partitioning of trace gases within CO2-water systems. The key advantages of this system are (1) The system can be isolated with no external exchange, making it ideal for experiments with conservative tracers. (2) Both phases can be sampled concurrently to give an accurate composition at each phase at any given time. (3) Use of a lower temperature flow loop outside of the reactor removes contamination and facilitates sampling. (4) Rapid equilibration at given pressure/temperature conditions is significantly aided by stirring and circulating the water phase using a magnetic stirrer and high-pressure liquid chromatography pump, respectively.

Applications of an NMHC isotope analysis system on trace gases from plant and CARIBIC samples

NASA Astrophysics Data System (ADS)

Zuiderweg, A.; Holzinger, R.; Röckmann, T.; Brenninkmeijer, C. A. M.

2009-04-01

Isotope analysis can be a useful tool in constraining the budgets (sources and sinks) of atmospheric trace species and is increasingly applied for organic constituents. We present initial results from an automated system for isotope ratio measurements on atmospheric hydrocarbons. The inlet system is flexible and allows analysis of trace gases from medium size to large ambient air samples (5-300L) as well as CO2-concentrates from samples that have been extracted offline. Long-term testing has shown this system to be stable to 1.5‰ vs. VPDB (or better) across all tested C2-C6 compounds, and methyl chloride. This system has now been utilized to analyze emissions rates and isotopic fractionation of 7 NMHCs from Sequoia leaf litter under conditions of UV exposure. These experiments indicate, for example, δ13C depletion in methyl chloride (CH3Cl) In the range of -90 to -113 v. VPDB with continuously increasing emission rates reaching to 3.26 ng/h/gdw after constant UV exposure of 7 hours, in a dynamic reactor. Other experiments with variation in UV exposure were also undertaken, indicating variation in emission rates and δ13C with UV intensity. In addition, first results from analysis of samples from concentrates taken during the CARIBIC II (http://www.caribic-atmospheric.com/) campaign, beginning with flight 26 (return flight, Male, Maldives, to Dusseldorf, Germany, August 2000), which features flight path air originating from over the Atlantic Ocean and the Indian subcontinent, is presented.

Photoacoustic trace detection of gases at the parts-per-quadrillion level with a moving optical grating.

PubMed

Xiong, Lian; Bai, Wenyu; Chen, Feifei; Zhao, Xian; Yu, Fapeng; Diebold, Gerald J

2017-07-11

The amplitude of the photoacoustic effect for an optical source moving at the sound speed in a one-dimensional geometry increases linearly in time without bound in the linear acoustic regime. Here, use of this principle is described for trace detection of gases, using two frequency-shifted beams from a CO 2 laser directed at an angle to each other to give optical fringes that move at the sound speed in a cavity with a longitudinal resonance. The photoacoustic signal is detected with a high-[Formula: see text], piezoelectric crystal with a resonance on the order of [Formula: see text] kHz. The photoacoustic cell has a design analogous to a hemispherical laser resonator and can be adjusted to have a longitudinal resonance to match that of the detector crystal. The grating frequency, the length of the resonator, and the crystal must all have matched frequencies; thus, three resonances are used to advantage to produce sensitivity that extends to the parts-per-quadrillion level.

Measurements of trace contaminants in closed-type plant cultivation chambers

NASA Astrophysics Data System (ADS)

Tani, A.; Kiyota, M.; Aiga, I.; Nitta, K.; Tako, Y.; Ashida, A.; Otsubo, K.; Saito, T.

Trace contaminants generated in closed facilities can cause abnormal plant growth. We present measurement data of trace contaminants released from soils, plants, and construction materials. We mainly used two closed chambers, a Closed-type Plant and Mushroom Cultivation Chamber (PMCC) and Closed-type Plant Cultivation Equipment (CPCE). Although trace gas budgets from soils obtained in this experiment are only one example, the results indicate that the budgets of trace gases, as well as CO_2 and O_2, change greatly with the degree of soil maturation and are dependent on the kind of substances in the soil. Both in the PMCC and in the CPCE, trace gases such as dioctyl phthalate (DOP), dibutyl phthalate (DBP), toluene and xylene were detected. These gases seemed to be released from various materials used in the construction of these chambers. The degree of increase in these trace gas levels was dependent on the relationship between chamber capacity and plant quantity. Results of trace gas measurement in the PMCC, in which lettuce and shiitake mushroom were cultivated, showed that ethylene was released both from lettuce and from the mushroom culture bed. The release rates were about 90 ng bed^-1 h^-1 for the shiitake mushroom culture bed (volume is 1700 cm^3) and 4.1 ~ 17.3 ng dm^-2h^-1 (leaf area basis) for lettuce. Higher ethylene release rates per plant and per unit leaf area were observed in mature plants than in young plants.

Humic substances and trace metals associated with Fe and Al oxides deposited in an acidic mountain stream

USGS Publications Warehouse

McKnight, Diane M.; Wershaw, R. L.; Bencala, K.E.; Zellweger, G.W.; Feder, G.L.

1992-01-01

Hydrous iron and aluminum oxides are deposited on the streambed in the confluence of the Snake River and Deer Creek, two streams in the Colorado Rocky Mountains. The Snake River is acidic and has high concentrations of dissolved Fe and Al. These metals precipitate at the confluence with the pristine, neutral pH, Deer Creek because of the greater pH (4.5-6.0) in the confluence. The composition of the deposited oxides changes consistently with distance downstream, with the most upstream oxide samples having the greatest Fe and organic carbon content. Fulvic acid accounts for most of the organic content of the oxides. Results indicate that streambed oxides in the confluence are not saturated with respect to their capacity to sorb dissolved humic substances from streamwater. The contents of several trace metals (Mn, Zn, Cu, Pb, Ni and Co) also decrease with distance downstream and are correlated with both the Fe and organic carbon contents. Strong metal-binding sites associated with the sorbed fulvic acid are more than sufficient to account for the trace metal content of the oxides. Complexation of trace metals by sorbed fulvic acid may explain the observed downstream decrease in trace metal content.

Critical issues in trace gas biogeochemistry and global change.

PubMed

Beerling, David J; Nicholas Hewitt, C; Pyle, John A; Raven, John A

2007-07-15

The atmospheric composition of trace gases and aerosols is determined by the emission of compounds from the marine and terrestrial biospheres, anthropogenic sources and their chemistry and deposition processes. Biogenic emissions depend upon physiological processes and climate, and the atmospheric chemistry is governed by climate and feedbacks involving greenhouse gases themselves. Understanding and predicting the biogeochemistry of trace gases in past, present and future climates therefore demands an interdisciplinary approach integrating across physiology, atmospheric chemistry, physics and meteorology. Here, we highlight critical issues raised by recent findings in all of these key areas to provide a framework for better understanding the past and possible future evolution of the atmosphere. Incorporating recent experimental and observational findings, especially the influence of CO2 on trace gas emissions from marine algae and terrestrial plants, into earth system models remains a major research priority. As we move towards this goal, archives of the concentration and isotopes of N2O and CH4 from polar ice cores extending back over 650,000 years will provide a valuable benchmark for evaluating such models. In the Pre-Quaternary, synthesis of theoretical modelling with geochemical and palaeontological evidence is also uncovering the roles played by trace gases in episodes of abrupt climatic warming and ozone depletion. Finally, observations and palaeorecords across a range of timescales allow assessment of the Earth's climate sensitivity, a metric influencing our ability to decide what constitutes 'dangerous' climate change.

Capture of trace sulfur gases from binary mixtures by single-walled carbon nanotube arrays: a molecular simulation study.

PubMed

Wang, Wenjuan; Peng, Xuan; Cao, Dapeng

2011-06-01

Adsorption of H(2)S and SO(2) pure gases and their selective capture from the H(2)S-CH(4), H(2)S-CO(2), SO(2)-N(2), and SO(2)-CO(2) binary mixtures by the single-walled carbon nanotubes (SWNT) are investigated via using the grand canonical Monte Carlo (GCMC) method. It is found that the (20, 20) SWNT with larger diameter shows larger capacity for H(2)S and SO(2) pure gases at T = 303 K, in which the uptakes reach 16.31 and 16.03 mmol/g, respectively. However, the (6,6) SWNT with small diameter exhibits the largest selectivity for binary mixtures containing trace sulfur gases at T = 303 K and P = 100 kPa. By investigating the effect of pore size on the separation of gas mixtures, we found that the optimized pore size is 0.81 nm for separation of H(2)S-CH(4), H(2)S-CO(2), and SO(2)-N(2) binary mixtures, while it is 1.09 nm for the SO(2)-CO(2) mixture. The effects of concentration and temperature on the selectivity of sulfide are also studied at the optimal pore size. It is found that the concentration (ppm) of sulfur components has little effect on selectivity of SWNTs for these binary mixtures. However, the selectivity decreases obviously with the increase of temperature. To improve the adsorption capacities, we further modify the surface of SWNTs with the functional groups. The selectivities of H(2)S-CO(2) and SO(2)-CO(2) mixtures are basically uninfluenced by the site density, while the increase of site density can improve the selectivity of H(2)S-CH(4) mixture doubly. It is expected that this work could provide useful information for sulfur gas capture.

The Effects of Various Amendments on Trace Element Stabilization in Acidic, Neutral, and Alkali Soil with Similar Pollution Index

PubMed Central

Kim, Min-Suk; Min, Hyun-Gi; Lee, Sang-Hwan; Kim, Jeong-Gyu

2016-01-01

Many studies have examined the application of soil amendments, including pH change-induced immobilizers, adsorbents, and organic materials, for soil remediation. This study evaluated the effects of various amendments on trace element stabilization and phytotoxicity, depending on the initial soil pH in acid, neutral, and alkali conditions. As in all types of soils, Fe and Ca were well stabilized on adsorption sites. There was an effect from pH control or adsorption mechanisms on the stabilization of cationic trace elements from inorganic amendments in acidic and neutral soil. Furthermore, acid mine drainage sludge has shown great potential for stabilizing most trace elements. In a phytotoxicity test, the ratio of the bioavailable fraction to the pseudo-total fraction significantly affected the uptake of trace elements by bok choy. While inorganic amendments efficiently decreased the bioavailability of trace elements, significant effects from organic amendments were not noticeable due to the short-term cultivation period. Therefore, the application of organic amendments for stabilizing trace elements in agricultural soil requires further study. PMID:27835687

The Effects of Various Amendments on Trace Element Stabilization in Acidic, Neutral, and Alkali Soil with Similar Pollution Index.

PubMed

Kim, Min-Suk; Min, Hyun-Gi; Lee, Sang-Hwan; Kim, Jeong-Gyu

2016-01-01

Many studies have examined the application of soil amendments, including pH change-induced immobilizers, adsorbents, and organic materials, for soil remediation. This study evaluated the effects of various amendments on trace element stabilization and phytotoxicity, depending on the initial soil pH in acid, neutral, and alkali conditions. As in all types of soils, Fe and Ca were well stabilized on adsorption sites. There was an effect from pH control or adsorption mechanisms on the stabilization of cationic trace elements from inorganic amendments in acidic and neutral soil. Furthermore, acid mine drainage sludge has shown great potential for stabilizing most trace elements. In a phytotoxicity test, the ratio of the bioavailable fraction to the pseudo-total fraction significantly affected the uptake of trace elements by bok choy. While inorganic amendments efficiently decreased the bioavailability of trace elements, significant effects from organic amendments were not noticeable due to the short-term cultivation period. Therefore, the application of organic amendments for stabilizing trace elements in agricultural soil requires further study.

High temperature abatement of acid gases from waste incineration. Part I: experimental tests in full scale plants.

PubMed

Biganzoli, Laura; Racanella, Gaia; Rigamonti, Lucia; Marras, Roberto; Grosso, Mario

2015-02-01

In recent years, several waste-to-energy plants in Italy have experienced an increase of the concentration of acid gases (HCl, SO2 and HF) in the raw gas. This is likely an indirect effect of the progressive decrease of the amount of treated municipal waste, which is partially replaced by commercial waste. The latter is characterised by a higher variability of its chemical composition because of the different origins, with possible increase of the load of halogen elements such as chlorine (Cl) and fluorine (F), as well as of sulphur (S). A new dolomitic sorbent was then tested in four waste-to-energy plants during standard operation as a pre-cleaning stage, to be directly injected at high temperature in the combustion chamber. For a sorbent injection of about 6 kg per tonne of waste, the decrease of acid gases concentration downstream the boiler was in the range of 7-37% (mean 23%) for HCl, 34-95% (mean 71%) for SO2 and 39-80% (mean 63%) for HF. This pre-abatement of acid gases allowed to decrease the feeding rate of the traditional low temperature sorbent (sodium bicarbonate in all four plants) by about 30%. Furthermore, it was observed by the plant operators that the sorbent helps to keep the boiler surfaces cleaner, with a possible reduction of the fouling phenomena and a consequent increase of the specific energy production. A preliminary quantitative estimate was carried out in one of the four plants. Copyright © 2014 Elsevier Ltd. All rights reserved.

Application of ion-induced nucleation mass spectrometry in the analysis of trace gases evolved from a polyimide film during the thermal curing stages

NASA Technical Reports Server (NTRS)

Smith, A. C.

1982-01-01

Trace gases evolved from a polyimide film during its thermal curing stages have been studied using ion-induced nucleation mass spectrometry. The technique involved exposing the test gas sample to a low energy beta source and recording the masses of the ion-induced molecular clusters formed in the reaction chamber. On the basis of the experimentally observed molecular cluster spectra, it has been concluded that the dominant trace component had a molecular weight of 87 atomic mass units. This component has been identified as a molecule of dimethylacetamide (DMAC) which had been used as a solvent in the preparation of the test polyimide specimen. This identification has been further confirmed by comparing the spectra of the test gas sample and the DMAC calibration sample obtained with a conventional mass spectrometer. The advantages of the ion-induced nucleation mass spectrometer versus the conventional mass spectrometer are discussed.

Process for the removal of acid forming gases from exhaust gases

DOEpatents

Chang, Shih-Ger; Liu, David K.

1992-01-01

Exhaust gases are treated to remove NO or NO.sub.x and SO.sub.2 by contacting the gases with an aqueous emulsion or suspension of yellow phosphorus preferably in a wet scrubber. The pressure is not critical, and ambient pressures are used. Hot water temperatures are best, but economics suggest about 50.degree. C. are attractive. The amount of yellow phosphorus used will vary with the composition of the exhaust gas, less than 3% for small concentrations of NO, and 10% or higher for concentrations above say 1000 ppm. Similarly, the pH will vary with the composition being treated, and it is adjusted with a suitable alkali. For mixtures of NO.sub.x and SO.sub.2, alkalis that are used for flue gas desulfurization are preferred. With this process, 100% of the by-products created are usable, and close to 100% of the NO or NO and SO.sub.2 can be removed in an economic fashion.

Process for the removal of acid forming gases from exhaust gases

DOEpatents

Chang, S.G.; Liu, D.K.

1992-11-17

Exhaust gases are treated to remove NO or NO[sub x] and SO[sub 2] by contacting the gases with an aqueous emulsion or suspension of yellow phosphorus preferably in a wet scrubber. The pressure is not critical, and ambient pressures are used. Hot water temperatures are best, but economics suggest about 50 C is attractive. The amount of yellow phosphorus used will vary with the composition of the exhaust gas, less than 3% for small concentrations of NO, and 10% or higher for concentrations above say 1000 ppm. Similarly, the pH will vary with the composition being treated, and it is adjusted with a suitable alkali. For mixtures of NO[sub x] and SO[sub 2], alkalis that are used for flue gas desulfurization are preferred. With this process, 100% of the by-products created are usable, and close to 100% of the NO or NO[sub x] and SO[sub 2] can be removed in an economic fashion. 9 figs.

Biological production of products from waste gases

DOEpatents

Gaddy, James L.

2002-01-22

A method and apparatus are designed for converting waste gases from industrial processes such as oil refining, and carbon black, coke, ammonia, and methanol production, into useful products. The method includes introducing the waste gases into a bioreactor where they are fermented to various products, such as organic acids, alcohols, hydrogen, single cell protein, and salts of organic acids by anaerobic bacteria within the bioreactor. These valuable end products are then recovered, separated and purified.

Trace gas emissions from the marine biosphere.

PubMed

Liss, Peter S

2007-07-15

A wide variety of trace gases (e.g. dimethyl sulphide, organohalogens, ammonia, non-methane and oxygenated hydrocarbons, volatile oxygenated organics and nitrous oxide) are formed in marine waters by biological and photochemical processes. This leads in many, but not all, cases to supersaturation of the water relative to marine air concentrations and a net flux of trace gas to the atmosphere. Since the gases are often in their reduced forms in the water, once in the atmosphere they are subject to oxidation by photolysis or radical attack to form chemically reactive species that can affect the oxidizing capacity of the air. They can also lead to the formation of new particles or the growth of existing ones that can then contribute to both direct and indirect (via the formation of cloud condensation nuclei) aerosol effects on climate. These cycles are discussed with respect to their impacts on the chemistry of the atmosphere, climate and human health. This whole topic was the subject of an extensive review (Nightingale & Liss 2003 In Treatise in geochemistry (eds H. D. Holland & K. K. Turekian), pp. 49-81) and what will be attempted here is a brief update of the earlier paper. There is no attempt to be comprehensive either in terms of gases covered or to give a complete review of all the recent literature. It is a personal view of recent advances both from my own research group as well as significant work from others. Questions raised at the meeting 'Trace gas biogeochemistry and global change' are dealt with at appropriate places in the text (rather than at the end of the piece). Discussion of each of the gases or group of gases is given in the following separate sections.

Differential Effects of Low-Molecular-Weight Organic Acids on the Mobilization of Soil-Borne Arsenic and Trace Metals.

PubMed

Nworie, Obinna Elijah; Qin, Junhao; Lin, Chuxia

2017-08-21

A batch experiment was conducted to examine the effects of six low-molecular-weight organic acids on the mobilization of arsenic and trace metals from a range of contaminated soils. The results showed that the organic acids behaved differently when reacting with soil-borne As and trace metals. Oxalic acid and acetic acid had the strongest and weakest capacity to mobilize the investigated elements, respectively. The solubilisation of iron oxides by the organic acids appears to play a critical role in mobilizing other trace metals and As. Apart from acidification and complexation, reductive dissolution played a dominant role in the dissolution of iron oxides in the presence of oxalic acid, while acidification tended to be more important for dissolving iron oxides in the presence of other organic acids. The unique capacity of oxalic acid to solubilize iron oxides tended to affect the mobilization of other elements in different ways. For Cu, Mn, and Zn, acidification-driven mobilization was likely to be dominant while complexation might play a major role in Pb mobilization. The formation of soluble Fe and Pb oxalate complexes could effectively prevent arsenate or arsenite from combining with these metals to form solid phases of Fe or Pb arsenate or arsenite.

Infrared measurements of atmospheric gases above Mauna Loa, Hawaii, in February 1987

NASA Technical Reports Server (NTRS)

Rinsland, C. P.; Goldman, A.; Murcray, F. J.; Murcray, F. H.; Blatherwick, R. D.

1988-01-01

The IR absorptions spectra of 13 minor and trace atmospheric gases, recorded by the NOAA's Geophysical Monitoring for Climate Change (GMCC) program station at Mauna Loa, Hawaii, for four days in February 1987, were analyzed to determine simultaneous total vertical column amounts for these gases. Comparisons with other data indicate that the NOAA GMCC surface volume mixing ratios are good measures of the mean volume mixing ratios of these gases in the troposphere and that Mauna Loa is a favorable site for IR monitoring of atmospheric gases. The ozone total columns deduced from the IR spectra agreed with the correlative Umkehr observations.

Trace Gas Retrievals from the GeoTASO Aircraft Instrument During the DISCOVER-AQ Campaigns

NASA Astrophysics Data System (ADS)

Nowlan, C. R.; Liu, X.; Leitch, J. W.; Liu, C.; Gonzalez Abad, G.; Chance, K.; Delker, T.; Good, W. S.; Murcray, F.; Ruppert, L.; Kaptchen, P. F.; Loughner, C.; Follette-Cook, M. B.; Pickering, K. E.

2014-12-01

The Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) instrument is a recently-developed passive remote sensing instrument capable of making 2-D measurements of trace gases from aircraft. GeoTASO was developed under NASA's Instrument Incubator program and is a test-bed instrument for the Geostationary Coastal and Air Pollution Events (GEO-CAPE) decadal survey and the upcoming Tropospheric Emissions: Monitoring of Pollution (TEMPO) satellite missions. The instrument collects spectra of backscattered UV-visible radiation for the detection of tropospheric trace gases such as NO2, ozone, formaldehyde and SO2. GeoTASO flew on the NASA HU-25C Falcon aircraft during the 2013 (Texas) and 2014 (Colorado) DISCOVER-AQ field campaigns, making satellite-analog measurements of trace gases at a spatial resolution of approximately 500x500 m over urban areas, power plants and other industrial sources of pollution. We present the GeoTASO retrieval algorithms, trace gas measurement results, and validation comparisons with ground-based observations and other aircraft instruments during these campaigns.

Acid Rain

USGS Publications Warehouse

Bricker, Owen P.; Rice, Karen C.

1995-01-01

Although acid rain is fading as a political issue in the United States and funds for research in this area have largely disappeared, the acidity of rain in the Eastern United States has not changed significantly over the last decade, and it continues to be a serious environmental problem. Acid deposition (commonly called acid rain) is a term applied to all forms of atmospheric deposition of acidic substances - rain, snow, fog, acidic dry particulates, aerosols, and acid-forming gases. Water in the atmosphere reacts with certain atmospheric gases to become acidic. For example, water reacts with carbon dioxide in the atmosphere to produce a solution with a pH of about 5.6. Gases that produce acids in the presence of water in the atmosphere include carbon dioxide (which converts to carbonic acid), oxides of sulfur and nitrogen (which convert to sulfuric and nitric acids}, and hydrogen chloride (which converts to hydrochloric acid). These acid-producing gases are released to the atmosphere through natural processes, such as volcanic emissions, lightning, forest fires, and decay of organic matter. Accordingly, precipitation is slightly acidic, with a pH of 5.0 to 5.7 even in undeveloped areas. In industrialized areas, most of the acid-producing gases are released to the atmosphere from burning fossil fuels. Major emitters of acid-producing gases include power plants, industrial operations, and motor vehicles. Acid-producing gases can be transported through the atmosphere for hundreds of miles before being converted to acids and deposited as acid rain. Because acids tend to build up in the atmosphere between storms, the most acidic rain falls at the beginning of a storm, and as the rain continues, the acids "wash out" of the atmosphere.

Note: A dual temperature closed loop batch reactor for determining the partitioning of trace gases within CO{sub 2}-water systems

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

Warr, Oliver, E-mail: oliver.warr@earth.ox.ac.uk; Ballentine, Christopher J.; Rochelle, Christopher A.

An experimental approach is presented which can be used to determine partitioning of trace gases within CO{sub 2}-water systems. The key advantages of this system are (1) The system can be isolated with no external exchange, making it ideal for experiments with conservative tracers. (2) Both phases can be sampled concurrently to give an accurate composition at each phase at any given time. (3) Use of a lower temperature flow loop outside of the reactor removes contamination and facilitates sampling. (4) Rapid equilibration at given pressure/temperature conditions is significantly aided by stirring and circulating the water phase using a magneticmore » stirrer and high-pressure liquid chromatography pump, respectively.« less

El Chichon - Composition of plume gases and particles

NASA Technical Reports Server (NTRS)

Kotra, J. P.; Finnegan, D. L.; Zoller, W. H.; Hart, M. A.; Moyers, J. L.

1983-01-01

Aircraft measurements were made of trace gases, atmospheric particles, and condensed acid volatiles in the plume of El Chichon volcano, Chiapas, Mexico, in November 1982. Hydrogen sulfide was the primary gaseous sulfur species in the plume at the time of collection. Concentrations of 28 elements were determined by neutron activation analysis of particulate material from the plume. The volatile elements sulfur, chlorine, arsenic, selenium, bromine, antimony, iodine, tungsten, and mercury were enriched relative to bulk pyroclastic material by factors of 60 to 20,000. Arsenic, antimony, and selenium were associated predominantly with small (not greater than 3 micrometer) particles. Calcium and sodium were present almost exclusively on larger particles and aluminum and manganese were bimodally distributed. Ashladen particulate material injected into the stratosphere during the early violent eruptions was enriched by factors of 10 to 30 relative to ash in some of the same elements observed in the quiescent plume.

[Remote sensing of atmospheric trace gas by airborne passive FTIR].

PubMed

Gao, Min-quang; Liu, Wen-qing; Zhang, Tian-shu; Liu, Jian-guo; Lu, Yi-huai; Wang, Ya-ping; Xu, Liang; Zhu, Jun; Chen, Jun

2006-12-01

The present article describes the details of aviatic measurement for remote sensing trace gases in atmosphere under various surface backgrounds with airborne passive FTIR. The passive down viewing and remote sensing technique used in the experiment is discussed. The method of acquiring atmospheric trace gases infrared characteristic spectra in complicated background and the algorithm of concentration retrieval are discussed. The concentrations of CO and N2O of boundary-layer atmosphere in experimental region below 1000 m are analyzed quantitatively. This measurement technique and the data analysis method, which does not require a previously measured background spectrum, allow fast and mobile remote detection and identification of atmosphere trace gas in large area, and also can be used for urgent monitoring of pollution accidental breakout.

A Pilot-Scale Evaluation of a New Technology to Control NO(x) Emissions from Boilers at KSC: Hydrogen Peroxide Injection into Boiler Flue Gases Followed by Wet Scrubbing of Acid Gases

NASA Technical Reports Server (NTRS)

Cooper, C. David

1997-01-01

Emissions of nitrogen oxides NO(x) are a significant problem in the United States. NO(x) are formed in any combustion process, therefore it is not surprising that NO(x) are emitted from the boilers at KSC. Research at UCF has shown (in the laboratory) that injecting H2O2 into hot simulated flue gases can oxidize the NO and NO2 to their acid gas forms, HNO2 and HNO3, respectively. These acid gases are much more water soluble than their counterparts, and theoretically can be removed easily by wet scrubbing. This technology was of interest to NASA, both for their boilers at KSC, and for their combustion sources elsewhere. However, it was necessary to field test the technology and to provide pilot-scale data to aid in design of full-scale facilities. Hence this project was initiated in May of 1996.

Analysis of trace inorganic anions in weak acid salts by single pump cycling-column-switching ion chromatography.

PubMed

Huang, Zhongping; Ni, Chengzhu; Zhu, Zhuyi; Pan, Zaifa; Wang, Lili; Zhu, Yan

2015-05-01

The application of ion chromatography with the single pump cycling-column-switching technique was described for the analysis of trace inorganic anions in weak acid salts within a single run. Due to the hydrogen ions provided by an anion suppressor electrolyzing water, weak acid anions could be transformed into weak acids, existing as molecules, after passing through the suppressor. Therefore, an anion suppressor and ion-exclusion column were adopted to achieve on-line matrix elimination of weak acid anions with high concentration for the analysis of trace inorganic anions in weak acid salts. A series of standard solutions consisting of target anions of various concentrations from 0.005 to 10 mg/L were analyzed, with correlation coefficients r ≥ 0.9990. The limits of detection were in the range of 0.67 to 1.51 μg/L, based on the signal-to-noise ratio of 3 and a 25 μL injection volume. Relative standard deviations for retention time, peak area, and peak height were all less than 2.01%. A spiking study was performed with satisfactory recoveries between 90.3 and 104.4% for all anions. The chromatographic system was successfully applied to the analysis of trace inorganic anions in five weak acid salts. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Variations of trace gases over the Bay of Bengal during the summer monsoon

NASA Astrophysics Data System (ADS)

Girach, I. A.; Ojha, Narendra; Nair, Prabha R.; Tiwari, Yogesh K.; Kumar, K. Ravi

2018-02-01

In situ measurements of near-surface ozone (O3), carbon monoxide (CO), and methane (CH4) were carried out over the Bay of Bengal (BoB) as a part of the Continental Tropical Convergence Zone (CTCZ) campaign during the summer monsoon season of 2009. O3, CO and CH4 mixing ratios varied in the ranges of 8-54 ppbv, 50-200 ppbv and 1.57-2.15 ppmv, respectively during 16 July-17 August 2009. The spatial distribution of mean tropospheric O3 from satellite retrievals is found to be similar to that in surface O3 observations, with higher levels over coastal and northern BoB as compared to central BoB. The comparison of in situ measurements with the Monitoring Atmospheric Composition & Climate (MACC) global reanalysis shows that MACC simulations reproduce the observations with small mean biases of 1.6 ppbv, -2.6 ppbv and 0.07 ppmv for O3, CO and CH4, respectively. The analysis of diurnal variation of O3 based on observations and the simulations from Weather Research and Forecasting coupled with Chemistry (WRF-Chem) at a stationary point over the BoB did not show a net photochemical build up during daytime. Satellite retrievals show limitations in capturing CH4 variations as measured by in situ sample analysis highlighting the need of more shipborne in situ measurements of trace gases over this region during monsoon.

Trace gas emissions from chaparral and boreal forest fires

NASA Technical Reports Server (NTRS)

Cofer, Wesley R., III; Levine, Joel S.; Sebacher, Daniel I.; Winstead, Edward L.; Riggan, Philip J.; Stocks, Brian J.; Brass, James A.; Ambrosia, Vincent G.

1989-01-01

Using smoke samples collected during low-level helicopter flights, the mixing ratios of CO2, CO, CH4, total nonmethane hydrocarbons, H2, and N2O over burning chaparral in southern California and over a burning boreal forest site in northern Ontario, Canada, were determined. Carbon dioxide-normalized emission ratios were determined for each trace gas for conditions of flaming, mixed, and smoldering combustion. The emission ratios for these trace gases were found to be highest for the smoldering combustion, generally thought to be the least efficient combustion stage. However, high emission ratios for these gases could be also produced during very vigorous flaming combustion.

Predicting the toxicity of sediment-associated trace metals with simultaneously extracted trace metal: Acid-volatile sulfide concentrations and dry weight-normalized concentrations: A critical comparison

USGS Publications Warehouse

Long, E.R.; MacDonald, D.D.; Cubbage, J.C.; Ingersoll, C.G.

1998-01-01

The relative abilities of sediment concentrations of simultaneously extracted trace metal: acid-volatile sulfide (SEM: AVS) and dry weight-normalized trace metals to correctly predict both toxicity and nontoxicity were compared by analysis of 77 field-collected samples. Relative to the SEM:AVS concentrations, sediment guidelines based upon dry weight-normalized concentrations were equally or slightly more accurate in predicting both nontoxic and toxic results in laboratory tests.

Retrieval of trace gas concentrations over Summit Station, Greenland using moderate-resolution spectral infrared radiances

NASA Astrophysics Data System (ADS)

Bahramvash Shams, S.; Walden, V. P.; Turner, D. D.

2017-12-01

Measurements of trace gases at high temporal resolution are important for understanding variations and trends at high latitudes. Trace gases over Greenland can be influenced by both long-range transport from pollution sources as well as local chemical processes. Satellite retrievals are an important data source in the polar regions, but accurate ground-based measurements are needed for proper validation, especially in data sparse regions. A moderate-resolution (0.5 cm-1) Fourier transform infrared spectrometer (FTIR), the Polar Atmospheric Emitted Radiance Interferometer (P-AERI), has been operated at Summit Station, Greenland as part of the ICECAPS project since 2010. In this study, trace gas concentrations, including ozone, nitrous oxide, and methane are retrieved using different optimal estimation retrieval codes. We first present results of retrieved gases using synthetic spectra (from a radiative transfer model) that mimic P-AERI measurements to evaluate systematic errors in the inverse models. We also retrieve time series of trace gas concentrations during periods of clear skies over Summit. We investigate the amount of vertical information that can be obtained with moderate resolution spectra for each of the trace gases, and also the impact of the seasonal variation of atmospheric water vapor on the retrievals. Data from surface observations and ozonesondes obtained by the NOAA Global Monitoring Division are used to improve the retrievals and as validation.

Trace gases over Northern Eurasia: background level and disturbing factors

NASA Astrophysics Data System (ADS)

Skorokhod, A.; Shumsky, R.; Pankratova, N.; Moiseenko, K.; Vasileva, A.; Berezina, E.; Elansky, N.

2012-04-01

Atmospheric air composition over the vast and low inhabited areas of Northern Eurasia is still poorly studied because of lack of the precise direct measurements. This harms to accuracy of both global and regional models which simulate climatological and ecosystem changes in that highly important region. In this work background trace gases (such as O3, NO, NO2, CO) concentrations and their variability are considered on base of results of continuous measurements at ZOTTO station in the middle of Siberia which have been carried out since March, 2007. Also factors implying background regime (like long-range transport, wild fires emissions) are analyzed. To compliment study data of TROICA train-based campaigns which have been regularly provided across Russia for many years (1995-2010) are used. The concentration of ozone has a pronounced seasonal variation with a clear peak in spring (40-45 ppbv in average and up to 80 ppbv in extreme cases) and minimum in winter. Average ozone level is about 20 ppbv that corresponds to the background conditions. Enhanced concentration in March-July is due to increased stratospheric-tropospheric exchange. In autumn and winter distribution of ozone is close to uniform. Photochemical processes under low light and air temperature does not cause the generation of ozone. Sink on the snow surface is very small, and therefore the diurnal variations are absent. In general, seasonal variations correspond to the average seasonal course, which is typical for Russia. The analysis of diurnal ozone variations in Zotino in different seasons showed that the maximum rate of ozone formation is observed in summer from 9 to 15 h local time and is 1-2 ppbv/hour. It correlates well with the data on the isoprene emissions and others biogenic VOC reacting with OH- radical. Thus they are biogenic VOC emissions that seem to be the main factor of the lower troposphere oxidation power in summer. In other seasons it is significantly lower. NOx concentration does

Interaction between common organic acids and trace nucleation species in the Earth's atmosphere.

PubMed

Xu, Yisheng; Nadykto, Alexey B; Yu, Fangqun; Herb, J; Wang, Wei

2010-01-14

Atmospheric aerosols formed via nucleation in the Earth's atmosphere play an important role in the aerosol radiative forcing associated directly with global climate changes and public health. Although it is well-known that atmospheric aerosol particles contain organic species, the chemical nature of and physicochemical processes behind atmospheric nucleation involving organic species remain unclear. In the present work, the interaction of common organic acids with molecular weights of 122, 116, 134, 88, 136, and 150 (benzoic, maleic, malic, pyruvic, phenylacetic, and tartaric acids) with nucleation precursors and charged trace species has been investigated. We found a moderate strong effect of the organic species on the stability of neutral and charged ionic species. In most cases, the free energies of the mixed H(2)SO(4)-organic acid dimer formation are within 1-1.5 kcal mol(-1) of the (H(2)SO(4))(NH(3)) formation energy. The interaction of the organic acids with trace ionic species is quite strong, and the corresponding free energies far exceed those of the (H(3)O(+))(H(2)SO(4)) and (H(3)O(+))(H(2)SO(4))(2) formation. These considerations lead us to conclude that the aforementioned organic acids may possess a substantial capability of stabilizing both neutral and positively charged prenucleation clusters, and thus, they should be studied further with regard to their involvement in the gas-to-particle conversion in the Earth's atmosphere.

Processes to remove acid forming gases from exhaust gases

DOEpatents

Chang, Shih-Ger

1994-01-01

The present invention relates to a process for reducing the concentration of NO in a gas, which process comprises: (A) contacting a gas sample containing NO with a gaseous oxidizing agent to oxidize the NO to NO.sub.2 ; (B) contacting the gas sample of step (A) comprising NO.sub.2 with an aqueous reagent of bisulfite/sulfite and a compound selected from urea, sulfamic acid, hydrazinium ion, hydrazoic acid, nitroaniline, sulfanilamide, sulfanilic acid, mercaptopropanoic acid, mercaptosuccinic acid, cysteine or combinations thereof at between about 0.degree. and 100.degree. C. at a pH of between about 1 and 7 for between about 0.01 and 60 sec; and (C) optionally contacting the reaction product of step (A) with conventional chemical reagents to reduce the concentrations of the organic products of the reaction in step (B) to environ-mentally acceptable levels. Urea or sulfamic acid are preferred, especially sulfamic acid, and step (C) is not necessary or performed.

Processes to remove acid forming gases from exhaust gases

DOEpatents

Chang, S.G.

1994-09-20

The present invention relates to a process for reducing the concentration of NO in a gas, which process comprises: (A) contacting a gas sample containing NO with a gaseous oxidizing agent to oxidize the NO to NO[sub 2]; (B) contacting the gas sample of step (A) comprising NO[sub 2] with an aqueous reagent of bisulfite/sulfite and a compound selected from urea, sulfamic acid, hydrazinium ion, hydrazoic acid, nitroaniline, sulfanilamide, sulfanilic acid, mercaptopropanoic acid, mercaptosuccinic acid, cysteine or combinations thereof at between about 0 and 100 C at a pH of between about 1 and 7 for between about 0.01 and 60 sec; and (C) optionally contacting the reaction product of step (A) with conventional chemical reagents to reduce the concentrations of the organic products of the reaction in step (B) to environmentally acceptable levels. Urea or sulfamic acid are preferred, especially sulfamic acid, and step (C) is not necessary or performed. 16 figs.

Assessment of acid leachable trace metals in sediment cores from River Uppanar, Cuddalore, Southeast coast of India.

PubMed

Ayyamperumal, T; Jonathan, M P; Srinivasalu, S; Armstrong-Altrin, J S; Ram-Mohan, V

2006-09-01

An acid leachable technique is employed in core samples (C1, C2 and C3) to develop a baseline data on the sediment quality for trace metals of River Uppanar, Cuddalore, southeast coast of India. Acid leachable metals (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn and Cd) indicate peak values at the sulphidic phase and enrichment of metals in the surface layers are due to the anthropogenic activities. Association of trace metals with Fe, Mn indicates their adsorption onto Fe-Mn oxyhydroxides and their correlation with S indicate that they are precipitated as metal sulphides. Factor analysis identified three possible types of geochemical associations and the supremacy of trace metals along with Fe, Mn, S and mud supports their geochemical associations. Factor analysis also signifies that anthropogenic activities have affected both the estuarine and fresh water regions of River Uppanar.

A new WRF-Chem treatment for studying regional-scale impacts of cloud processes on aerosol and trace gases in parameterized cumuli

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

Berg, L. K.; Shrivastava, M.; Easter, R. C.

A new treatment of cloud effects on aerosol and trace gases within parameterized shallow and deep convection, and aerosol effects on cloud droplet number, has been implemented in the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) version 3.2.1 that can be used to better understand the aerosol life cycle over regional to synoptic scales. The modifications to the model include treatment of the cloud droplet number mixing ratio; key cloud microphysical and macrophysical parameters (including the updraft fractional area, updraft and downdraft mass fluxes, and entrainment) averaged over the population of shallow clouds, or a single deep convectivemore » cloud; and vertical transport, activation/resuspension, aqueous chemistry, and wet removal of aerosol and trace gases in warm clouds. These changes have been implemented in both the WRF-Chem chemistry packages as well as the Kain–Fritsch (KF) cumulus parameterization that has been modified to better represent shallow convective clouds. Testing of the modified WRF-Chem has been completed using observations from the Cumulus Humilis Aerosol Processing Study (CHAPS). The simulation results are used to investigate the impact of cloud–aerosol interactions on regional-scale transport of black carbon (BC), organic aerosol (OA), and sulfate aerosol. Based on the simulations presented here, changes in the column-integrated BC can be as large as –50% when cloud–aerosol interactions are considered (due largely to wet removal), or as large as +40% for sulfate under non-precipitating conditions due to sulfate production in the parameterized clouds. The modifications to WRF-Chem are found to account for changes in the cloud droplet number concentration (CDNC) and changes in the chemical composition of cloud droplet residuals in a way that is consistent with observations collected during CHAPS. Efforts are currently underway to port the changes described here to the latest version of WRF-Chem, and it

Local and transboundary factors' impacts on trace gases and aerosol during haze episode in 2015 El Niño in Malaysia.

PubMed

Samsuddin, Nur Adilla Che; Khan, Md Firoz; Maulud, Khairul Nizam Abdul; Hamid, Ahmad Hazuwan; Munna, Fahia Tarannum; Rahim, Muhammad Aizat Ab; Latif, Mohd Talib; Akhtaruzzaman, Md

2018-07-15

Southeast Asian haze is a semi-natural phenomenon that chokes the region each year during the dry monsoon season. Smoke-haze episodes caused by the vegetation and peat fires in Indonesia severely affected large parts of Malaysia during the 2015 El Niño phenomenon. This study aimed to evaluate the factors that influenced the concentrations of aerosol and trace gases during the 2015 haze and non-haze period on a semi-urban site in the southern part of Malaysian peninsula that facing Sumatra (Muar, Site A), and on an urban site near to Kuala Lumpur, influenced by the city centre (Cheras, Site B). Local land use data and the cluster of air mass weighted backward trajectory were used to identify the potential factors from local sources and the transboundary region, respectively. The annual median concentrations of PM 10 for semi-urban and urban sites were 45.0μg/m 3 and 47.0μg/m 3 , respectively for the study period (Jan-Dec 2015) from the hourly observation dataset. The highest PM 10 concentrations during the haze were 358μg/m 3 and 415μg/m 3 for the two sites, respectively, representing absolutely unhealthy air. However, the trace gases were within the safe threshold. The average concentrations of PM 10 and carbon monoxide were two fold higher during the haze than the non-haze episodes on both sites. Nitrogen dioxide was more influenced by haze compared with sulphur dioxide and ozone. The results of the land use change suggest that the local factor can also partially affect the air pollution on the urban area (Site B) but more visible in 2015. The results of the backward trajectory and the wildfire radiative power showed that the smoke-haze episodes that affected Malaysia in 2015 were mainly initiated in the Indonesian Sumatra and Kalimantan regions. This study provides a very useful information towards the impacted region during El Niño haze episode. Copyright © 2017 Elsevier B.V. All rights reserved.

A new WRF-Chem treatment for studying regional-scale impacts of cloud processes on aerosol and trace gases in parameterized cumuli

DOE PAGES

Berg, L. K.; Shrivastava, M.; Easter, R. C.; ...

2015-02-24

A new treatment of cloud effects on aerosol and trace gases within parameterized shallow and deep convection, and aerosol effects on cloud droplet number, has been implemented in the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) version 3.2.1 that can be used to better understand the aerosol life cycle over regional to synoptic scales. The modifications to the model include treatment of the cloud droplet number mixing ratio; key cloud microphysical and macrophysical parameters (including the updraft fractional area, updraft and downdraft mass fluxes, and entrainment) averaged over the population of shallow clouds, or a single deep convectivemore » cloud; and vertical transport, activation/resuspension, aqueous chemistry, and wet removal of aerosol and trace gases in warm clouds. These changes have been implemented in both the WRF-Chem chemistry packages as well as the Kain–Fritsch (KF) cumulus parameterization that has been modified to better represent shallow convective clouds. Testing of the modified WRF-Chem has been completed using observations from the Cumulus Humilis Aerosol Processing Study (CHAPS). The simulation results are used to investigate the impact of cloud–aerosol interactions on regional-scale transport of black carbon (BC), organic aerosol (OA), and sulfate aerosol. Based on the simulations presented here, changes in the column-integrated BC can be as large as –50% when cloud–aerosol interactions are considered (due largely to wet removal), or as large as +40% for sulfate under non-precipitating conditions due to sulfate production in the parameterized clouds. The modifications to WRF-Chem are found to account for changes in the cloud droplet number concentration (CDNC) and changes in the chemical composition of cloud droplet residuals in a way that is consistent with observations collected during CHAPS. Efforts are currently underway to port the changes described here to the latest version of WRF-Chem, and it

Trace gas detection in hyperspectral imagery using the wavelet packet subspace

NASA Astrophysics Data System (ADS)

Salvador, Mark A. Z.

This dissertation describes research into a new remote sensing method to detect trace gases in hyperspectral and ultra-spectral data. This new method is based on the wavelet packet transform. It attempts to improve both the computational tractability and the detection of trace gases in airborne and spaceborne spectral imagery. Atmospheric trace gas research supports various Earth science disciplines to include climatology, vulcanology, pollution monitoring, natural disasters, and intelligence and military applications. Hyperspectral and ultra-spectral data significantly increases the data glut of existing Earth science data sets. Spaceborne spectral data in particular significantly increases spectral resolution while performing daily global collections of the earth. Application of the wavelet packet transform to the spectral space of hyperspectral and ultra-spectral imagery data potentially improves remote sensing detection algorithms. It also facilities the parallelization of these methods for high performance computing. This research seeks two science goals, (1) developing a new spectral imagery detection algorithm, and (2) facilitating the parallelization of trace gas detection in spectral imagery data.

Where do California's greenhouse gases come from?

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

Fischer, Marc

2009-12-11

Last March, more than two years after California passed legislation to slash greenhouse gas emissions 25 percent by 2020, Lawrence Berkeley National Laboratory scientist Marc Fischer boarded a Cessna loaded with air monitoring equipment and crisscrossed the skies above Sacramento and the Bay Area. Instruments aboard the aircraft measured a cocktail of greenhouse gases: carbon dioxide from fossil fuel use, methane from livestock and landfills, CO2 from refineries and power plants, traces of nitrous oxide from agriculture and fuel use, and industrially produced other gases like refrigerants. The flight was part of the Airborne Greenhouse Gas Emissions Survey, a collaborationmore » between Berkeley Lab, the National Oceanic and Atmospheric Administration, and the University of California, and UC Davis to pinpoint the sources of greenhouse gases in central California. The survey is intended to improve inventories of the states greenhouse gas emissions, which in turn will help scientists verify the emission reductions mandated by AB-32, the legislation enacted by California in 2006.« less

Understanding Biogenic and Anthropogenic Trace Gas Variations Measured Near Cool, CA in June 2010

NASA Astrophysics Data System (ADS)

Klein, B. Z.; Flowers, B. A.; Gorkowski, K.; Dubey, M. K.; Knighton, W. B.; Floerchinger, C.; Herndon, S. C.; Fast, J. D.; Zaveri, R. A.

2011-12-01

Trace gas signatures produced by forested and urban areas differ greatly. Forested areas are dominated by gases produced during photosynthesis and respiration: CO2 and volatile organic compounds (VOCs) including terpenes and isoprene. Urban areas are heavily influenced by vehicle exhaust emissions and have elevated levels of CO, NOx and aromatic hydrocarbons such as benzene. Ozone is produced as a byproduct of both of these sources; it is produced when NOx from urban areas reacts with either anthropogenic or biogenic hydrocarbons. The Carbonaceous Aerosol and Radiative Effects Study (CARES) campaign was conducted during June 2010, in part to observe the evolution of urban air masses as they mix into rural locations and to better understand anthropogenic-biogenic photochemical interactions. The campaign included two ground-based sampling sites, one in Sacramento, CA (T0) and one downwind, approximately 70km NE, rurally located near Cool, CA (T1). In situ measurements of CO2, CO, O3, NO and multiple different VOCs were performed at the T1 site during the study, and are analyzed here to gain insights into the chemistry and transport of these trace gases. Comparisons between these trace gases coupled with transport modeling is used to delineate biogenic and anthropogenic sources. Additionally, comparisons between trace gases produced predominately by biogenic sources provide valuable information on how meteorology affects their production. Two atmospheric models (HYSPLIT back-trajectories and WRF forecasts) are used to predict transport episodes, where polluted air masses from the Sacramento or more distant San Francisco areas are transported to Cool. The two models display significant overlap for eleven different transport episodes during the study period. Both models also agree on two transport-free multiple-day periods. By examining the periods during which the models are in agreement, we are able to characterize with high certainty the trace gas signatures of local

Advanced Global Atmospheric Gases Experiment (AGAGE)

NASA Technical Reports Server (NTRS)

Prinn, Ronald G.; Kurylo, Michael (Technical Monitor)

2004-01-01

We seek funding from NASA for the third year (2005) of the four-year period January 1, 2003 - December 31, 2006 for continued support of the MIT contributions to the multi-national global atmospheric trace species measurement program entitled Advanced Global Atmospheric Gases Experiment (AGAGE). The case for real-time high-frequency measurement networks like AGAGE is very strong and the observations and their interpretation are widely recognized for their importance to ozone depletion and climate change studies and to verification issues arising from the Montreal Protocol (ozone) and Kyoto Protocol (climate). The proposed AGAGE program is distinguished by its capability to measure over the globe at high frequency almost all of the important species in the Montreal Protocol and almost all of the significant non-CO2 gases in the Kyoto Protocol.

Low-Energy Collisions of Protonated Enantiopure Amino Acids with Chiral Target Gases

NASA Astrophysics Data System (ADS)

Kulyk, K.; Rebrov, O.; Ryding, M.; Thomas, R. D.; Uggerud, E.; Larsson, M.

2017-12-01

Here we report on the gas-phase interactions between protonated enantiopure amino acids ( l- and d-enantiomers of Met, Phe, and Trp) and chiral target gases [( R)- and ( S)-2-butanol, and ( S)-1-phenylethanol] in 0.1-10.0 eV low-energy collisions. Two major processes are seen to occur over this collision energy regime, collision-induced dissociation and ion-molecule complex formation. Both processes were found to be independent of the stereo-chemical composition of the interacting ions and targets. These data shed light on the currently debated mechanisms of gas-phase chiral selectivity by demonstrating the inapplicability of the three-point model to these interactions, at least under single collision conditions. [Figure not available: see fulltext.

Characteristics of aerosol particles and trace gases in ship exhaust plumes

NASA Astrophysics Data System (ADS)

Drewnick, F.; Diesch, J.; Borrmann, S.

2011-12-01

Gaseous and particulate matter from marine vessels gain increasing attention due to their significant contribution to the anthropogenic burden of the atmosphere, implying the change of the atmospheric composition and the impact on local and regional air quality and climate (Eyring et al., 2010). As ship emissions significantly affect air quality of onshore regions, this study deals with various aspects of gas and particulate plumes from marine traffic measured near the Elbe river mouth in northern Germany. In addition to a detailed investigation of the chemical and physical particle properties from different types of commercial marine vessels, we will focus on the chemistry of ship plumes and their changes while undergoing atmospheric processing. Measurements of the ambient aerosol, various trace gases and meteorological parameters using a mobile laboratory (MoLa) were performed on the banks of the Lower Elbe which is passed on average, daily by 30 ocean-going vessels reaching the port of Hamburg, the second largest freight port of Europe. During 5 days of sampling from April 25-30, 2011 170 commercial marine vessels were probed at a distance of about 1.5-2 km with high temporal resolution. Mass concentrations in PM1, PM2.5 and PM10 and number as well as PAH and black carbon (BC) concentrations in PM1 were measured; size distribution instruments covered the size range from 6 nm up to 32 μm. The chemical composition of the non-refractory aerosol in the submicron range was measured by means of an Aerosol Mass Spectrometer (Aerodyne HR-ToF-AMS). Gas phase species analyzers monitored various trace gas concentrations in the air and a weather station provided meteorological parameters. Additionally, a wide spectrum of ship information for each vessel including speed, size, vessel type, fuel type, gross tonnage and engine power was recorded via Automatic Identification System (AIS) broadcasts. Although commercial marine vessels powered by diesel engines consume high

Field Measurements of Trace Gases and Aerosols Emitted by Undersampled Combustion Sources Including Wood and Dung Cooking Fires, Garbage and Crop Residue Burning, and Indonesian Peat Fires

NASA Astrophysics Data System (ADS)

Stockwell, C.; Jayarathne, T. S.; Goetz, D.; Simpson, I. J.; Selimovic, V.; Bhave, P.; Blake, D. R.; Cochrane, M. A.; Ryan, K. C.; Putra, E. I.; Saharjo, B.; Stone, E. A.; DeCarlo, P. F.; Yokelson, R. J.

2017-12-01

Field measurements were conducted in Nepal and in the Indonesian province of Central Kalimantan to improve characterization of trace gases and aerosols emitted by undersampled combustion sources. The sources targeted included cooking with a variety of stoves, garbage burning, crop residue burning, and authentic peat fires. Trace gas and aerosol emissions were studied using a land-based Fourier transform infrared spectrometer, whole air sampling, photoacoustic extinctiometers (405 and 870nm), and filter samples that were analyzed off-line. These measurements were used to calculate fuel-based emission factors (EFs) for up to 90 gases, PM2.5, and PM2.5 constituents. The aerosol optical data measured included EFs for the scattering and absorption coefficients, the single scattering albedo (at 870 and 405 nm), as well as the absorption Ångström exponent. The emissions varied significantly by source, although light absorption by both brown and black carbon (BrC and BC, respectively) was important for all non-peat sources. For authentic peat combustion, the emissions of BC were negligible and absorption was dominated by organic aerosol. The field results from peat burning were in reasonable agreement with recent lab measurements of smoldering Kalimantan peat and compare well to the limited data available from other field studies. The EFs can be used with estimates of fuel consumption to improve regional emissions inventories and assessments of the climate and health impacts of these undersampled sources.

Adsorption and reaction mechanism of arsenic vapors over γ-Al2O3 in the simulated flue gas containing acid gases.

PubMed

Hu, Hongyun; Chen, Dunkui; Liu, Huan; Yang, Yuhan; Cai, Hexun; Shen, Junhao; Yao, Hong

2017-08-01

Arsenic emission from fuel combustion and metal smelting flue gas causes serious pollution. Addition of sorbents is a promising way for the arsenic capture from high temperature flue gas. However, it is difficult to remove arsenic from SO 2 /HCl-rich flue gas due to the competitive reaction of the sorbents with arsenic and these acid gases. To solve this problem, arsenic adsorption over γ-Al 2 O 3 was studied in this work to evaluate its adsorption mechanism, resistance to acid gases as well as regeneration behavior. The results show that γ-Al 2 O 3 had good resistance to acid gases and the arsenic adsorption by γ-Al 2 O 3 could be effectively carried out at a wide temperature range between 573 and 1023 K. Nevertheless, adsorption at higher-temperature (like 1173 K) leaded to the decrease of surface area and the rearrangement of crystal structure of γ-Al 2 O 3 , reducing the active sites for arsenic adsorption. The adsorption of arsenic was confirmed to occur at different active sites in γ-Al 2 O 3 by forming various adsorbed species. Increasing temperature facilitated arsenic transformation into more stable chemisorbed As 3+ and As 5+ which were difficult to remove through thermal treatment regeneration. Fortunately, the regeneration of spent γ-Al 2 O 3 could be well performed using NaOH solution. Copyright © 2017 Elsevier Ltd. All rights reserved.

Process for the removal of acid forming gases from exhaust gases and production of phosphoric acid

DOEpatents

Chang, Shih-Ger; Liu, David K.

1992-01-01

Exhaust gases are treated to remove NO or NO.sub.x and SO.sub.2 by contacting the gases with an aqueous emulsion or suspension of yellow phosphorous preferably in a wet scrubber. The addition of yellow phosphorous in the system induces the production of O.sub.3 which subsequently oxidizes NO to NO.sub.2. The resulting NO.sub.2 dissolves readily and can be reduced to form ammonium ions by dissolved SO.sub.2 under appropriate conditions. In a 20 acfm system, yellow phosphorous is oxidized to yield P.sub.2 O.sub.5 which picks up water to form H.sub.3 PO.sub.4 mists and can be collected as a valuable product. The pressure is not critical, and ambient pressures are used. Hot water temperatures are best, but economics suggest about 50.degree. C. The amount of yellow phosphorus used will vary with the composition of the exhaust gas, less than 3% for small concentrations of NO, and 10% or higher for concentrations above say 1000 ppm. Similarly, the pH will vary with the composition being treated, and it is adjusted with a suitable alkali. For mixtures of NO.sub.x and SO.sub.2, alkalis that are used for flue gas desulfurization are preferred. With this process, better than 90% of SO.sub.2 and NO in simulated flue gas can be removed. Stoichiometric ratios (P/NO) ranging between 0.6 and 1.5 were obtained.

Raman scattering investigations of the interaction of a COV with pure and acid doped ice particles

NASA Astrophysics Data System (ADS)

Facq, S.; Oancea, A.; Focsa, C.; Chazallon, B.

2009-04-01

Ice present in polar stratosphere is as well a common component of the troposphere, particularly in cirrus clouds widespread in tropopause and upper troposphere region. With water droplets, ice constitutes the condensed matter that can interact with atmospheric trace gases via many different trapping processes (co-deposition i.e; incorporation during growing ice conditions, adsorption, freezing etc). The incorporation of trace gases in ice surface/volume can both affect the atmospheric chemistry and the ice structure and reactivity. This can therefore modify the nature and composition of the incorporated species in ice, or in the gas phase. Recently, field measurements have demonstrated the presence of nitric acid in ice particles from cirrus clouds(1,2) (concentration between 0.63 wt% and 2.5 wt %). Moreover, laboratory experiments have shown that the uptake of atmospheric trace gases can be enhanced up to 1 or 2 orders of magnitude in these doped ice particles. Among trace gases capable to interact with atmospheric condensed matter figure volatile organic compounds such as aldehydes, ketones and alcohols (ex: ethanol and methanol). They play an important role in the upper troposphere (3,4) and snowpack chemistry (5) as they can be easily photolysed, producing free radicals and so influence the oxidizing capacity and the ozone-budget of the atmosphere (3,4). The temperature range at which these physico-chemical processes occur extents between ~ 190 K and 273K. Interaction between ice and trace gases are therefore largely dependent on the ice surface properties as well as on the phase formation dynamic (crystalline or not). This study aims to examine and characterize the incorporation of a COV (ex: ethanol), at the surface or in the volume of ice formed by different growth mechanisms (vapour deposition or droplets freezing). Vibrational spectra of water OH and ethanol CH-spectral regions are analysed using confocal micro-Raman spectroscopy at different temperatures

Balloon-borne photoionization mass spectrometer for measurement of stratospheric gases

NASA Technical Reports Server (NTRS)

Aikin, A. C.; Maier, E. J. R.

1978-01-01

A balloon-borne photoionization mass spectrometer used to measure stratospheric trace gases is described. Ions are created with photons from high-intensity krypton discharge lamps and a quadrupole mass analyzer is employed for ion identification. Differential pumping is achieved with liquid helium cryopumping. To insure measurement of unperturbed stratospheric air, the entire system is contained in a sealed gondola and the atmospheric sample is taken some distance away during descent. The photoionization technique allows the detection of a low ionization potential constituent, such as nitric oxide, at less than a part in one billion in the presence of the major atmospheric gases and their isotopes. Operation of the mass spectrometer system was demonstrated during a daytime flight from Palestine, Texas on 26 April 1977. The sensitivity achieved and the unique selectivity afforded by this technique offer a capability for trace constituent measurement not possible with the more conventional electron impact ionization approach.

Preparation and analysis of zero gases for the measurement of trace VOCs in air monitoring

NASA Astrophysics Data System (ADS)

Englert, Jennifer; Claude, Anja; Demichelis, Alessia; Persijn, Stefan; Baldan, Annarita; Li, Jianrong; Plass-Duelmer, Christian; Michl, Katja; Tensing, Erasmus; Wortman, Rina; Ghorafi, Yousra; Lecuna, Maricarmen; Sassi, Guido; Sassi, Maria Paola; Kubistin, Dagmar

2018-06-01

Air quality observations are performed globally to monitor the status of the atmosphere and its level of pollution and to assess mitigation strategies. Regulations of air quality monitoring programmes in various countries demand high-precision measurements for harmful substances often at low trace concentrations. These requirements can only be achieved by using high-quality calibration gases including high-purity zero gas. For volatile organic compound (VOC) observations, zero gas is defined as being hydrocarbon-free and can be, for example, purified air, nitrogen or helium. It is essential for the characterisation of the measurement devices and procedures, for instrument operation as well as for calibrations. Two commercial and one self-built gas purifiers were tested for their VOC removal efficiency following a standardised procedure. The tested gas purifiers included one adsorption cartridge with an inorganic media and two types of metal catalysts. A large range of VOCs were investigated, including the most abundant species typically measured at air monitoring stations. Both catalysts were able to remove a large range of VOCs whilst the tested adsorption cartridge was not suitable to remove light compounds up to C4. Memory effects occurred for the adsorption cartridge when exposed to higher concentration. This study emphasises the importance of explicitly examining a gas purifier for its intended application before applying it in the field.

Climate change and trace gases.

PubMed

Hansen, James; Sato, Makiko; Kharecha, Pushker; Russell, Gary; Lea, David W; Siddall, Mark

2007-07-15

Palaeoclimate data show that the Earth's climate is remarkably sensitive to global forcings. Positive feedbacks predominate. This allows the entire planet to be whipsawed between climate states. One feedback, the 'albedo flip' property of ice/water, provides a powerful trigger mechanism. A climate forcing that 'flips' the albedo of a sufficient portion of an ice sheet can spark a cataclysm. Inertia of ice sheet and ocean provides only moderate delay to ice sheet disintegration and a burst of added global warming. Recent greenhouse gas (GHG) emissions place the Earth perilously close to dramatic climate change that could run out of our control, with great dangers for humans and other creatures. Carbon dioxide (CO2) is the largest human-made climate forcing, but other trace constituents are also important. Only intense simultaneous efforts to slow CO2 emissions and reduce non-CO2 forcings can keep climate within or near the range of the past million years. The most important of the non-CO2 forcings is methane (CH4), as it causes the second largest human-made GHG climate forcing and is the principal cause of increased tropospheric ozone (O3), which is the third largest GHG forcing. Nitrous oxide (N2O) should also be a focus of climate mitigation efforts. Black carbon ('black soot') has a high global warming potential (approx. 2000, 500 and 200 for 20, 100 and 500 years, respectively) and deserves greater attention. Some forcings are especially effective at high latitudes, so concerted efforts to reduce their emissions could preserve Arctic ice, while also having major benefits for human health, agricultural productivity and the global environment.

Polar Vortex Dynamics During Spring and Fall Diagnosed Using ATMOS Trace Gas Observation

NASA Technical Reports Server (NTRS)

Manney, G.; Michelsen, H.; Santee, M.; Gunson, M.; Irion, F.; Roche, A.; Livesey, N.

1999-01-01

Trace gases measured by the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument during the Mar/Apr 1992(AT-1), Apr 1993(AT-2), and Nov 1994(AT-3) space-shuttle missions have been mapped into equivalent latitude/potential temperature (EqL/0) coordinates.

Differential Radiometers Using Fabry-Perot Interferometric Technique for Remote Sensing Determination of Various Atmospheric Trace Gases

NASA Technical Reports Server (NTRS)

Georgieva, E. M.; Heaps, W. S.; Wilson, E. L.

2007-01-01

New type of remote sensing instrument based upon the Fabry-Perot inte rferometric technique has been developed at NASA's Goddard Space Flight Center. Fabry-Perot interferometry (FPI) is a well known, powerful spectroscopic technique and one of its many applications is to be use d to measure greenhouse gases and also some harmful species in the at mosphere. With this technique, absorption of particular species is me asured and related to its concentration. A solid Fabry-Perot etalon is used as a frequency filter to restrict the measurement to particular absorption bands of the gas of interest. With adjusting the thicknes s of the etalon that separation (in frequency) of the transmitted fri nges can be made equal to the almost constant separation of the gas a bsorption lines. By adjusting the temperature of the etalon, which changes the index of refi-action of its material, the transmission fring es can be brought into nearly exact correspondence with absorption li nes of the particular species. With this alignment between absorption lines and fringes, changes in the amount of a species in the atmosph ere strongly affect the amount of light transmitted by the etalon and can be related to gas concentration. The instrument that we have dev eloped detects the absorption of various atmospheric trace gases in d irect or reflected sunlight. Our instrument employing Fabry-Perot interferometer makes use of two features to achieve high sensitivity. The first is high spectral resolution enabling one to match the width of an atmospheric absorption feature by the instrumental band pass. The second is high optical throughput enabled by using multiple spectral lines simultaneously. For any species that one wishes to measure, thi s first feature is available while the use of multiple spectral features can be employed only for species with suitable spectra and freedom from interfering species in the same wavelength region. We have deve loped an instrument for use as ground based

Trace Gases - A Warning Signs of Impending Major Seismic Activity

NASA Astrophysics Data System (ADS)

Baijnath, J.; Freund, F.; Li, J.

2013-12-01

isopropanol and with a highly reduced butyn containing triple-bonded C and an aromatic ring were used. Multiple tests were conducted to study the interaction of stressed-activated positive hole charge carriers with organic versus inorganic and dry versus moist materials. This study suggests that the appearance of certain trace gases may be useful as a pre-earthquake indicator.

Characterization and analyses of acid-extractable and leached trace elements in dental cements.

PubMed

Camilleri, J; Kralj, P; Veber, M; Sinagra, E

2012-08-01

Determination of the elemental constitution and investigation of the total and leachable arsenic, chromium and lead in Portland cement, pure tricalcium silicate, Biodentine, Bioaggregate and mineral trioxide aggregate (MTA) Angelus. The chemical composition of Portland cement, MTA Angelus, tricalcium silicate cement, Biodentine and Bioaggregate was determined using X-ray fluorescence (XRF). Measurements of arsenic, lead and chromium were taken with inductively coupled plasma-mass spectrometry (ICP-MS), following acid digestion on the hydrated material and on leachates of cements soaked in Hank's balanced salt solution (HBSS). All the cements investigated had a similar oxide composition with the main oxide being calcium and silicon oxide. Both the Portland cement and MTA Angelus had an additional aluminium oxide. The dental cements included a radiopacifying material. All the materials tested had higher acid-extractable arsenic content than the level set by ISO 9917-1 (2007) and an acceptable level of lead. Regardless these high levels of trace elements present in the materials, the leaching in HBSS was minimal for all the dental material tested in contrast to the high levels displayed by Portland cement. Dental materials based on tricalcium silicate cement and MTA Angelus release minimal quantities of trace elements when in contact with simulated body fluids. The results of acid extraction could be affected by nonspecific matrix effects by the cement. © 2012 International Endodontic Journal.

Biological production of ethanol from waste gases with Clostridium ljungdahlii

DOEpatents

Gaddy, James L.

2000-01-01

A method and apparatus for converting waste gases from industrial processes such as oil refining, carbon black, coke, ammonia, and methanol production, into useful products is disclosed. The method includes introducing the waste gases into a bioreactor where they are fermented to various product, such as organic acids, alcohols H.sub.2, SCP, and salts of organic acids by anaerobic bacteria within the bioreactor. These valuable end products are then recovered, separated and purified.

Microscopic evaluation of trace metals in cloud droplets in an acid precipitation region.

PubMed

Li, Weijun; Wang, Yan; Collett, Jeffrey L; Chen, Jianmin; Zhang, Xiaoye; Wang, Zifa; Wang, Wenxing

2013-05-07

Mass concentrations of soluble trace metals and size, number, and mixing properties of nanometal particles in clouds determine their toxicity to ecosystems. Cloud water was found to be acidic, with a pH of 3.52, at Mt. Lu (elevation 1,165 m) in an acid precipitation region in South China. A combination of Inductively Coupled Plasma Mass Spectrometry (ICPMS) and Transmission Electron Microscopy (TEM) for the first time demonstrates that the soluble metal concentrations and solid metal particle number are surprisingly high in acid clouds at Mt. Lu, where daily concentrations of SO2, NO2, and PM10 are 18 μg m(-3), 7 μg m(-3), and 22 μg m(-3). The soluble metals in cloudwater with the highest concentrations were zinc (Zn, 200 μg L(-1)), iron (Fe, 88 μg L(-1)), and lead (Pb, 77 μg L(-1)). TEM reveals that 76% of cloud residues include metal particles that range from 50 nm to 1 μm diameter with a median diameter of 250 nm. Four major metal-associated particle types are Pb-rich (35%), fly ash (27%), Fe-rich (23%), and Zn-rich (15%). Elemental mapping shows that minor soluble metals are distributed within sulfates of cloud residues. Emissions of fine metal particles from large, nonferrous industries and coal-fired power plants with tall stacks were transported upward to this high elevation. Our results suggest that the abundant trace metals in clouds aggravate the impacts of acid clouds or associated precipitation on the ecosystem and human health.

Trace gas emissions from burning Florida wetlands

NASA Astrophysics Data System (ADS)

Cofer, Wesley R.; Levine, Joel S.; Winstead, Edward L.; Lebel, Peter J.; Koller, Albert M.; Hinkle, C. Ross

1990-02-01

Measurements of biomass burn-produced trace gases are presented that were obtained using a helicopter at low altitudes above burning Florida wetlands on November 9, 1987, and from both helicopter and light-aircraft samplings on November 7, 1988. Carbon dioxide (CO2) normalized emission ratios (ΔX/ΔCO2; V/V; where X is trace gas) for carbon monoxide (CO), hydrogen (H2), methane (CH4), total nonmethane hydrocarbons (TNMHC), and nitrous oxide (N2O) were obtained over burning graminoid wetlands consisting primarily of Spartina bakeri and Juncus roemerianus. Some interspersed scrub oak (Quercus spp) and saw palmetto (Screnoa repens) were also burned. No significant differences were observed in the emission ratios determined for these gases from samples collected over flaming, mixed, and smoldering phases of combustion during the 1987 fire. Combustion-categorized differences in emission ratios were small for the 1988 fire. Combustion efficiency was relatively good (low emission ratios for reduced gases) for both fires. We believe that the consistently low emission ratios were a unique result of graminoid wetlands fires, in which the grasses and rushes (both small-size fuels) burned rapidly down to standing water and were quickly extinguished. Consequently, the efficiency of the combustion was good and the amount and duration of smoldering combustion was greatly diminished.

Gas chromatography/trace analysis of derivatized azelaic acid as a stability marker.

PubMed

Alzweiri, Muhammed; Tarawneh, Ruba; Khanfar, Mohammad A

2013-10-01

Azelaic acid, a naturally occurring saturated dicarboxylic acid, is found in many topical formulations for its various medical benefits or as a byproduct of the oxidative decomposition of unsaturated fatty acids. The poor volatility of azelaic acid hinders its applicability in GC analysis. Therefore, azelaic acid was derivatized by methylation and silylation procedures to enhance its volatility for GC analysis. Accordingly, dimethyl azelate (DMA) and di(trimethylsilyl) azelate were synthesized and characterized by GC-MS. Subsequently, a GC with flame ionization detection method was developed and validated to analyze trace amounts of azelaic acid in some marketed skin creams. Unlike DMA, di(trimethylsilyl) azelate was chemically unstable and degraded within few hours. Nonane was used as a stable internal standard. Variability due to derivatization and extraction was controlled by a standard addition procedure. DMA analysis was linear in a wide concentration range (100 ng/mL to 100 mg/mL). Moreover, the method was accurate (96.4-103.4%) and precise with inter- and intraday variability <2.0% and LOQ and LOD of 100 and 10 ng/mL, respectively. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Origins of geothermal gases at Yellowstone

USGS Publications Warehouse

Lowenstern, Jacob B.; Bergfeld, Deborah; Evans, William C.; Hunt, Andrew G.

2015-01-01

Gas emissions at the Yellowstone Plateau Volcanic Field (YPVF) reflect open-system mixing of gas species originating from diverse rock types, magmas, and crustal fluids, all combined in varying proportions at different thermal areas. Gases are not necessarily in chemical equilibrium with the waters through which they vent, especially in acid sulfate terrain where bubbles stream through stagnant acid water. Gases in adjacent thermal areas often can be differentiated by isotopic and gas ratios, and cannot be tied to one another solely by shallow processes such as boiling-induced fractionation of a parent liquid. Instead, they inherit unique gas ratios (e.g., CH4/He) from the dominant rock reservoirs where they originate, some of which underlie the Quaternary volcanic rocks. Steam/gas ratios (essentially H2O/CO2) of Yellowstone fumaroles correlate with Ar/He and N2/CO2, strongly suggesting that H2O/CO2 is controlled by addition of steam boiled from water rich in atmospheric gases. Moreover, H2O/CO2 varies systematically with geographic location, such that boiling is more enhanced in some areas than others. The δ13C and 3He/CO2 of gases reflect a dominant mantle origin for CO2 in Yellowstone gas. The mantle signature is most evident at Mud Volcano, which hosts gases with the lowest H2O/CO2, lowest CH4 concentrations and highest He isotope ratios (~16Ra), consistent with either a young subsurface intrusion or less input of crustal and meteoric gas than any other location at Yellowstone. Across the YPVF, He isotope ratios (3He/4He) inversely vary with He concentrations, and reflect varied amounts of long- stored, radiogenic He added to the magmatic endmember within the crust. Similarly, addition of CH4 from organic-rich sediments is common in the eastern thermal areas at Yellowstone. Overall, Yellowstone gases reflect addition of deep, high-temperature magmatic gas (CO2-rich), lower-temperatures crustal gases (4He- and CH4-bearing), and those gases (N2, Ne, Ar) added

Sea salt aerosols as a reactive surface for inorganic and organic acidic gases in the Arctic troposphere

NASA Astrophysics Data System (ADS)

Chi, J. W.; Li, W. J.; Zhang, D. Z.; Zhang, J. C.; Lin, Y. T.; Shen, X. J.; Sun, J. Y.; Chen, J. M.; Zhang, X. Y.; Zhang, Y. M.; Wang, W. X.

2015-10-01

Sea salt aerosols (SSA) are dominant particles in the Arctic atmosphere and determine the polar radiative balance. SSA react with acidic pollutants that lead to changes in physical and chemical properties of their surface, which in turn alter their hygroscopic and optical properties. Transmission electron microscopy with energy-dispersive X-ray spectrometry was used to analyze morphology, composition, size, and mixing state of individual SSA at Ny-Ålesund, Svalbard, in summertime. Individual fresh SSA contained cubic NaCl coated by certain amounts of MgCl2 and CaSO4. Individual partially aged SSA contained irregular NaCl coated by a mixture of NaNO3, Na2SO4, Mg(NO3)2, and MgSO4. The comparison suggests the hydrophilic MgCl2 coating in fresh SSA likely intrigued the heterogeneous reactions at the beginning of SSA and acidic gases. Individual fully aged SSA normally had Na2SO4 cores and an amorphous coating of NaNO3. Elemental mappings of individual SSA particles revealed that as the particles ageing Cl gradually decreased, the C, N, O, and S content increased. 12C- mapping from nanoscale secondary ion mass spectrometry indicates that organic matter increased in the aged SSA compared with the fresh SSA. 12C- line scan further shows that organic matter was mainly concentrated on the aged SSA surface. These new findings indicate that this mixture of organic matter and NaNO3 on particle surfaces likely determines their hygroscopic and optical properties. These abundant SSA as reactive surfaces adsorbing inorganic and organic acidic gases can shorten acidic gas lifetime and influence the possible gaseous reactions in the Arctic atmosphere, which need to be incorporated into atmospheric chemical models in the Arctic troposphere.

Sea salt aerosols as a reactive surface for inorganic and organic acidic gases in the arctic troposphere

NASA Astrophysics Data System (ADS)

Li, W.

2016-12-01

Sea salt aerosols (SSA) are dominant particles in the arctic atmosphere and determine the polar radiative balance. SSA react with acidic pollutants that lead to changes of physical and chemical properties of their surface, which in turn alter their hygroscopic and optical properties. Transmission electron microscopy with energy-dispersive X-ray spectrometry was used to analyze morphology, composition, size, and mixing state of individual SSA at Ny-Ålesund, Svalbard in summertime. Individual fresh SSA contained cubic NaCl coated by certain amounts of MgCl2 and CaSO4. Individual partially aged SSA contained irregular NaCl coated by a mixture of NaNO3, Na2SO4, Mg(NO3)2, and MgSO4. The comparison suggests the hydrophilic MgCl2 coating in fresh SSA likely intrigued the heterogeneous reactions at the beginning of SSA and acidic gases. Individual fully aged SSA normally had Na2SO4 cores and an amorphous coating of NaNO3. Elemental mappings of individual SSA particles revealed that as the particles ageing Cl gradually decreased but the C, N, O, and S content increased. 12C- mapping from nanoscale secondary ion mass spectrometry indicates that organic matter increased in the aged SSA compared with the fresh SSA. 12C- line scan further shows that organic matter was mainly concentrated on the aged SSA surface. These new findings indicate that this mixture of organic matter and NaNO3 on particle surfaces likely determines their hygroscopic and optical properties. These abundant SSA as reactive surfaces absorbing inorganic and organic acidic gases can shorten acidic gas lifetime and influence the possible gaseous reactions in the arctic atmosphere, which need to be incorporated into atmospheric chemical models in the arctic troposphere.

Spatiotemporal Patterns of Urban Trace Gases and Pollutants Observed with a Light Rail Vehicle Platform in Salt Lake City, UT

NASA Astrophysics Data System (ADS)

Mitchell, L.; Crosman, E.; Fasoli, B.; Leclair-Marzolf, L.; Jacques, A.; Horel, J.; Lin, J. C.; Bowling, D. R.; Ehleringer, J. R.

2015-12-01

Urban environments are characterized by both spatial complexity and temporal variability, each of which present challenges for measurement strategies aimed at constraining estimates of greenhouse gas emissions and air quality. To address these challenges we initiated a project in December 2014 to measure trace species (CO2, CH4, O3, and Particulate Matter) by way of a Utah Transit Authority (UTA) light rail vehicle whose route traverses the Salt Lake Valley in Utah on an hourly basis, retracing the same route through commercial, residential, suburban, and rural typologies. Light rail vehicles present advantages as a measurement platform, including the absence of in-situ fossil fuel emissions, repeated transects across a urban region that provides both spatial and temporal information, and relatively low operating costs. We present initial results from the first year of operations including the spatiotemporal patterns of greenhouse gases and pollutants across Salt Lake City, UT with an emphasis on criteria pollutants, identification of sources, and future applications of this measurement platform.

The Analysis of PPM Levels of Gases in Air by Photoionization Mass Spectrometry

ERIC Educational Resources Information Center

Driscoll, John N.; Warneck, Peter

1973-01-01

Discusses analysis of trace gases in air by photoionization mass spectrometer. It is shown that the necessary sensitivity can be obtained by eliminating the UV monochromator and using direct ionization with a hydrogen light source. (JP)

First results of the observations of trace gases in the Martian atmosphere by the Planetary Fourier Spectrometer onboard the Mars Express

NASA Astrophysics Data System (ADS)

Titov, D. V.; Ignatiev, N.; Formisano, V.; Grassi, D.; Giuranna, M.; Maturilli, A.; Piccioni, G.; Moroz, V. I.; Lellouch, E.; Encrenaz, T.; Pfs Team

High spectral resolution observations of Mars by the PFS/Mars Express provide new insight into the atmospheric composition. Spectral features of atmospheric CO2 and its isotopes at 15, 4.3, 2.7, 1.4 μ m, CO at 4.7 and 2.35 μ m, and H2O at 40, 2.56, and 1.38 μ m as well as solar spectral features are clearly identified in the PFS spectra. HDO spectral details at 3.7 μ m were also tentatively detected. The paper will present qualitative and quantitative analysis of the PFS spectra in the regions of spectral bands of trace gases. Abundance of minor constituents will be determined using complete radiative transfer modeling including possible non-LTE effects. We will also present results of search for other minor species with emphasis on the limb observations that provide higher air mass factor.

Addition of granular activated carbon and trace elements to favor volatile fatty acid consumption during anaerobic digestion of food waste.

PubMed

Capson-Tojo, Gabriel; Moscoviz, Roman; Ruiz, Diane; Santa-Catalina, Gaëlle; Trably, Eric; Rouez, Maxime; Crest, Marion; Steyer, Jean-Philippe; Bernet, Nicolas; Delgenès, Jean-Philippe; Escudié, Renaud

2018-07-01

The effect of supplementing granular activated carbon and trace elements on the anaerobic digestion performance of consecutive batch reactors treating food waste was investigated. The results from the first batch suggest that addition of activated carbon favored biomass acclimation, improving acetic acid consumption and enhancing methane production. Adding trace elements allowed a faster consumption of propionic acid. A second batch proved that a synergy existed when activated carbon and trace elements were supplemented simultaneously. The degradation kinetics of propionate oxidation were particularly improved, reducing significantly the batch duration and improving the average methane productivities. Addition of activated carbon favored the growth of archaea and syntrophic bacteria, suggesting that interactions between these microorganisms were enhanced. Interestingly, microbial analyses showed that hydrogenotrophic methanogens were predominant. This study shows for the first time that addition of granular activated carbon and trace elements may be a feasible solution to stabilize food waste anaerobic digestion. Copyright © 2018 Elsevier Ltd. All rights reserved.

Interpretation of Trace Gas Data Using Inverse Methods and Global Chemical Transport Models

NASA Technical Reports Server (NTRS)

Prinn, Ronald G.

1997-01-01

This is a theoretical research project aimed at: (1) development, testing, and refining of inverse methods for determining regional and global transient source and sink strengths for long lived gases important in ozone depletion and climate forcing, (2) utilization of inverse methods to determine these source/sink strengths which use the NCAR/Boulder CCM2-T42 3-D model and a global 3-D Model for Atmospheric Transport and Chemistry (MATCH) which is based on analyzed observed wind fields (developed in collaboration by MIT and NCAR/Boulder), (3) determination of global (and perhaps regional) average hydroxyl radical concentrations using inverse methods with multiple titrating gases, and, (4) computation of the lifetimes and spatially resolved destruction rates of trace gases using 3-D models. Important goals include determination of regional source strengths of methane, nitrous oxide, and other climatically and chemically important biogenic trace gases and also of halocarbons restricted by the Montreal Protocol and its follow-on agreements and hydrohalocarbons used as alternatives to the restricted halocarbons.

The ice record of greenhouse gases: a view in the context of future changes

NASA Astrophysics Data System (ADS)

Raynaud, D.; Barnola, J.-M.; Chappellaz, J.; Blunier, T.; Indermühle, A.; Stauffer, B.

2000-01-01

Analysis of air trapped in polar ice provides the most direct information on the natural variability of Greenhouse Trace Gases (GTG). It gives the context for the dramatic change in their atmospheric concentrations induced by anthropogenic activities over the last 200 yr, leading to present-day levels which have been unprecedented over the last 400,000 yr. The GTG ice record also provides insight into the processes generally involved in the interplay between these trace gases and the climate and in particular those which are likely to take place in the next centuries in terms of climate changes and climate feedbacks on ecosystems. The paper gives selected examples of the GTG record, taken during different climatic periods in the past, and illustrating what we can learn in terms of processes.

Impact of simulated acid rain on trace metals and aluminum leaching in latosol from Guangdong Province, China

Treesearch

Jia-En Zhang; Jiayu Yu; Ying Ouyang; Huaqin Xu

2014-01-01

Acid rain is one of the most serious ecological and environmental problems worldwide. This study investigated the impacts of simulated acid rain (SAR) upon leaching of trace metals and aluminum (Al) from a soil. Soil pot leaching experiments were performed to investigate the impacts of SAR at five different pH levels (or treatments) over a 34-day period upon the...

Airborne mapping of Seoul's atmosphere: Trace gas measurements from GeoTASO during KORUS-AQ

NASA Astrophysics Data System (ADS)

Nowlan, C. R.; Al-Saadi, J. A.; Castellanos, P.; Chance, K.; Gonzalez Abad, G.; Janz, S. J.; Judd, L.; Kowalewski, M. G.; Liu, X.

2017-12-01

The Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) instrument is a pushbroom airborne remote sensing instrument capable of making measurements of air quality and ocean color using backscattered UV and visible light. GeoTASO is an airborne test-bed for the upcoming Tropospheric Emissions: Monitoring of Pollution (TEMPO) and Geostationary Environment Monitoring Spectrometer (GEMS) geostationary satellite missions, which will measure air quality over North America and Asia, respectively. GeoTASO also acts as a satellite analogue during field campaigns. GeoTASO flew on the NASA Langley Research Center UC-12 aircraft during the Korea-United States Air Quality Study in May-June 2016, collecting spectra over South Korea during 30 flights over 19 flight days. These observations can be used to derive 2-D maps of tropospheric trace gases including ozone, nitrogen dioxide, sulfur dioxide, formaldehyde, nitrous acid and glyoxal below the aircraft at spatial resolutions between 250 m x 250 m and 1 km x 1 km, depending on the gas. We present spatially resolved trace gas retrievals over Seoul and its surrounding industrial regions, and comparisons with correlative satellite and campaign data.

Are acid volatile sulfides (AVS) important trace metals sinks in semi-arid mangroves?

PubMed

Queiroz, Hermano Melo; Nóbrega, Gabriel Nuto; Otero, Xose L; Ferreira, Tiago Osório

2018-01-01

Acid-volatile sulfides (AVS) formation and its role on trace metals bioavailability were studied in semi-arid mangroves. The semi-arid climatic conditions at the studied sites, marked by low rainfall and high evapotranspiration rates, clearly limited the AVS formation (AVS contents varied from 0.10 to 2.34μmolg -1 ) by favoring oxic conditions (Eh>+350mV). The AVS contents were strongly correlated with reactive iron and organic carbon (r=0.84; r=0.83 respectively), evidencing their dominant role for AVS formation under semi-arid conditions. On the other hand, the recorded ΣSEM/AVS values remained >1 evidencing a little control of AVS over the bioavailability of trace metals and, thus, its minor role as a sink for toxic metals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sea salt aerosols as a reactive surface for inorganic and organic acidic gases in the arctic troposphere

NASA Astrophysics Data System (ADS)

Chi, J. W.; Li, W. J.; Zhang, D. Z.; Zhang, J. C.; Lin, Y. T.; Shen, X. J.; Sun, J. Y.; Chen, J. M.; Zhang, X. Y.; Zhang, Y. M.; Wang, W. X.

2015-06-01

Sea salt aerosols (SSA) are dominant particles in the arctic atmosphere and determine the polar radiative balance. SSA react with acidic pollutants that lead to changes of physical and chemical properties of their surface, which in turn alter their hygroscopic and optical properties. Transmission electron microscopy with energy-dispersive X-ray spectrometry was used to analyze morphology, composition, size, and mixing state of individual SSA at Ny-Ålesund, Svalbard in summertime. Individual fresh SSA contained cubic NaCl coated by certain amounts of MgCl2 and CaSO4. Individual partially aged SSA contained irregular NaCl coated by a mixture of NaNO3, Na2SO4, Mg(NO3)2, and MgSO4. The comparison suggests the hydrophilic MgCl2 coating in fresh SSA likely intrigued the heterogeneous reactions at the beginning of SSA and acidic gases. Individual fully aged SSA normally had Na2SO4 cores and an amorphous coating of NaNO3. Elemental mappings of individual SSA particles revealed that as the particles ageing Cl gradually decreased but the C, N, O, and S content increased. 12C14N- mapping from nanoscale secondary ion mass spectrometry indicates that organic matter increased in the aged SSA compared with the fresh SSA. 12C14N- line scans further show that organic matter was mainly concentrated on the aged SSA surface. These new findings indicate that this mixture of organic matter and NaNO3 on particle surfaces determines their hygroscopic and optical properties. These abundant SSA, whose reactive surfaces absorb inorganic and organic acidic gases in the arctic troposphere, need to be incorporated into atmospheric chemical models.

Structure-selective hot-spot Raman enhancement for direct identification and detection of trace penicilloic acid allergen in penicillin.

PubMed

Zhang, Liying; Jin, Yang; Mao, Hui; Zheng, Lei; Zhao, Jiawei; Peng, Yan; Du, Shuhu; Zhang, Zhongping

2014-08-15

Trace penicilloic acid allergen frequently leads to various fatal immune responses to many patients, but it is still a challenge to directly discriminate and detect its residue in penicillin by a chemosensing way. Here, we report that silver-coated gold nanoparticles (Au@Ag NPs) exhibit a structure-selective hot-spot Raman enhancement capability for direct identification and detection of trace penicilloic acid in penicillin. It has been demonstrated that penicilloic acid can very easily link Au@Ag NPs together by its two carboxyl groups, locating itself spontaneously at the interparticle of Au@Ag NPs to form strong Raman hot-spot. At the critical concentration inducing the nanoparticle aggregation, Raman-enhanced effect of penicilloic acid is ~60,000 folds higher than that of penicillin. In particular, the selective Raman enhancement to the two carboxyl groups makes the peak of carboxyl group at C6 of penicilloic acid appear as a new Raman signal due to the opening of β-lactam ring of penicillin. The surface-enhanced Raman scattering (SERS) nanoparticle sensor reaches a sensitive limit lower than the prescribed 1.0‰ penicilloic acid residue in penicillin. The novel strategy to examine allergen is more rapid, convenient and inexpensive than the conventional separation-based assay methods. Copyright © 2014 Elsevier B.V. All rights reserved.

Gas chromatographic analysis of trace impurities in chlorine trifluoride.

PubMed

Laurens, J B; Swinley, J M; de Coning, J P

2000-03-24

The gas chromatographic determination of trace gaseous impurities in highly reactive fluorinated gaseous matrices presents unique requirements to both equipment and techniques. Especially problematic are the gases normally present in ambient air namely oxygen and nitrogen. Analysing these gases at the low microl/l (ppm) level requires special equipment and this publication describes a custom-designed system utilising backflush column switching to protect the columns and detectors. A thermal conductivity detector with nickel filaments was used to determine ppm levels of impurities in ClF3.

Studies of Trace Gas Chemical Cycles Using Inverse Methods and Global Chemical Transport Models

NASA Technical Reports Server (NTRS)

Prinn, Ronald G.

2003-01-01

We report progress in the first year, and summarize proposed work for the second year of the three-year dynamical-chemical modeling project devoted to: (a) development, testing, and refining of inverse methods for determining regional and global transient source and sink strengths for long lived gases important in ozone depletion and climate forcing, (b) utilization of inverse methods to determine these source/sink strengths using either MATCH (Model for Atmospheric Transport and Chemistry) which is based on analyzed observed wind fields or back-trajectories computed from these wind fields, (c) determination of global (and perhaps regional) average hydroxyl radical concentrations using inverse methods with multiple titrating gases, and (d) computation of the lifetimes and spatially resolved destruction rates of trace gases using 3D models. Important goals include determination of regional source strengths of methane, nitrous oxide, methyl bromide, and other climatically and chemically important biogenic/anthropogenic trace gases and also of halocarbons restricted by the Montreal protocol and its follow-on agreements and hydrohalocarbons now used as alternatives to the restricted halocarbons.

Synergistic effect of Brønsted acid and platinum on purification of automobile exhaust gases

PubMed Central

Fu, Wei; Li, Xin-Hao; Bao, Hong-Liang; Wang, Kai-Xue; Wei, Xiao; Cai, Yi-Yu; Chen, Jie-Sheng

2013-01-01

The catalytic purification of automobile exhaust gases (CO, NOx and hydrocarbons) is one of the most practiced conversion processes used to lower the emissions and to reduce the air pollution. Nevertheless, the good performance of exhaust gas purification catalysts often requires the high consumption of noble metals such as platinum. Here we report that the Brønsted acid sites on the external surface of a microporous silicoaluminophosphate (SAPO) act as a promoter for exhaust gas purification, effectively cutting the loading amount of platinum in the catalyst without sacrifice of performance. It is revealed that in the Pt-loaded SAPO-CHA catalyst, there exists a remarkable synergistic effect between the Brønsted acid sites and the Pt nanoparticles, the former helping to adsorb and activate the hydrocarbon molecules for NO reduction during the catalytic process. The thermal stability of SAPO-CHA also makes the composite catalyst stable and reusable without activity decay. PMID:23907148

Synergistic effect of Brønsted acid and platinum on purification of automobile exhaust gases.

PubMed

Fu, Wei; Li, Xin-Hao; Bao, Hong-Liang; Wang, Kai-Xue; Wei, Xiao; Cai, Yi-Yu; Chen, Jie-Sheng

2013-01-01

The catalytic purification of automobile exhaust gases (CO, NOx and hydrocarbons) is one of the most practiced conversion processes used to lower the emissions and to reduce the air pollution. Nevertheless, the good performance of exhaust gas purification catalysts often requires the high consumption of noble metals such as platinum. Here we report that the Brønsted acid sites on the external surface of a microporous silicoaluminophosphate (SAPO) act as a promoter for exhaust gas purification, effectively cutting the loading amount of platinum in the catalyst without sacrifice of performance. It is revealed that in the Pt-loaded SAPO-CHA catalyst, there exists a remarkable synergistic effect between the Brønsted acid sites and the Pt nanoparticles, the former helping to adsorb and activate the hydrocarbon molecules for NO reduction during the catalytic process. The thermal stability of SAPO-CHA also makes the composite catalyst stable and reusable without activity decay.

WAVELENGTH-RESOLVED REMPI MASS SPECTROMETRY FOR THE MONITORING OF TOXIC INCINERATION TRACE GASES

EPA Science Inventory

Structure-selective measurement techniques are needed for the assessment of the toxic loading of incinerator gases. This review article shows that wavelength-resolved, resonance-enhanced, multiphoton- ionization (REMPY) mass spectrometry can be used to this end. In this case, how...

Evaluation of Saltzman and phenoldisulfonic acid methods for determining NO/sub x/ in engine exhaust gases

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

Groth, R.H.; Calabro, D.S.

1969-11-01

The two methods normally used for the analysis of NO/sub x/ are the Saltzman and the phenoldisulfonic acid technique. This paper describes an evaluation of these wet chemical methods to determine their practical application to engine exhaust gas analysis. Parameters considered for the Saltzman method included bubbler collection efficiency, NO to NO/sub 2/ conversion efficiency, masking effect of other contaminants usually present in exhaust gases and the time-temperature effect of these contaminants on store developed solutions. Collection efficiency and the effects of contaminants were also considered for the phenoldisulfonic acid method. Test results indicated satisfactory collection and conversion efficiencies formore » the Saltzman method, but contaminants seriously affected the measurement accuracy particularly if the developed solution was stored for a number of hours at room temperature before analysis. Storage at 32/sup 0/F minimized effect. The standard procedure for the phenoldisulfonic acid method gave good results, but the process was found to be too time consuming for routine analysis and measured only total NO/sub x/. 3 references, 9 tables.« less

TRACE ANALYSIS OF FLUORESCEIN-DERIVATIZED PHENOXY ACID HERBICIDES BY MICELLAR ELECTROKINETIC CHROMATOGRAPHY WITH LASER-INDUCTED FLUORESCENCE DETECTION

EPA Science Inventory

Micellar electrokinetic chromatography (MEKC) with laser-induced fluorescence (LIF) detection was used for the trace analysis of phenoxy acid herbicides. Capillary electrophoresis (CE) with LIF detection, which has not previously been used for pesticide analysis, overcomes the po...

Twenty Five Years of Airborne Observations of Ozone-Depleting and Climate-Related Gases in the Upper Troposphere and Lower Stratosphere.

NASA Astrophysics Data System (ADS)

Elkins, J. W.; Moore, F. L.; Hintsa, E. J.; Dutton, G. S.; Nance, J. D.; Hall, B. D.

2016-12-01

NOAA scientists started in situ airborne measurements of two strong ozone-depleting gases or chlorofluorocarbons, CFC-11 and CFC-113 in 1991 on the NASA ER-2 aircraft with a two-channel gas chromatograph, Airborne Chromatograph for Atmospheric Trace Species (ACATS). We broaden our list of gases to include more ozone-depleting and other climate-related gases. An improved 4-channel gas chromatograph that included N2O, SF6, CFC-11, -12, -113, halon-1211, CCl4, CH3CCl3, CH4, CO, and H2 was added to the ER-2 aircraft in 1994. As CFC replacements took hold, we add a gas chromatograph-mass spectrometer system, PAN and other Trace Hydro-halocarbon Experiment (PANTHER), to examine shorter-lived gases mainly in the upper troposphere. These airborne measurements were to complement of ground-based flask and in situ measurements from the NOAA Halocarbon and other Trace Species Network. This talk will show results from a tropical study, Airborne Tropical Tropopause Experiment (ATTREX) on the NASA Global Hawk aircraft and preliminary results from the Atmospheric Tomography Mission (ATom) conducted in August 2016 on the NASA DC-8 aircraft. A detrended, gridded, latitudinal distribution of SF6 is shown in the figure below for the years of 1994 through 2014. Such a plot may be useful to atmospheric modelers trying to capture transport or calculate emissions.

Extraterrestrial Amino Acids in Orgueil and Ivuna: Tracing the Parent Body of CI Type Carbonaceous Chondrites

NASA Technical Reports Server (NTRS)

Meyer, Michael (Technical Monitor); Ehrenfreund, Pascale; Glavin, Daniel P.; Bota, Oliver; Cooper, George; Bada, Jeffrey

2001-01-01

Amino acid analyses using HPLC of pristine interior pieces of the CI carbonaceous chondrites Orgueil and Ivuna have found that beta-alanine, glycine, and gamma-amino-n-butyric acid (ABA) are the most abundant amino acids in these two meteorites, with concentrations ranging from approx. 600 to 2,000 parts per billion (ppb). Other alpha-amino acids such as alanine, alpha-ABA, alpha-aminoisobutyric acid (AIB), and isovaline are present only in trace amounts (less than 200 ppb). Carbon isotopic measurements of beta-alanine and glycine and the presence of racemic (D/L 1) alanine and beta-ABA in Orgueil suggest that these amino acids are extraterrestrial in origin. In comparison to the CM carbonaceous chondrites Murchison and Murray, the amino acid composition of the CIs is strikingly distinct, suggesting that these meteorites came from a different type of parent body, possibly an extinct comet, than did the CM carbonaceous chondrites.

Photoacoustic Techniques for Trace Gas Sensing Based on Semiconductor Laser Sources

PubMed Central

Elia, Angela; Lugarà, Pietro Mario; Di Franco, Cinzia; Spagnolo, Vincenzo

2009-01-01

The paper provides an overview on the use of photoacoustic sensors based on semiconductor laser sources for the detection of trace gases. We review the results obtained using standard, differential and quartz enhanced photoacoustic techniques. PMID:22303143

Trace gas retrievals from Airborne Compact Atmospheric Mapper (ACAM) observations during the 2011 DISCOVER-AQ flight campaign

NASA Astrophysics Data System (ADS)

Liu, X.; Kowalewski, M. G.; Janz, S. J.; Bhartia, P. K.; Chance, K.; Krotkov, N. A.; Pickering, K. E.; Crawford, J. H.

2011-12-01

The DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) mission has just finished its first flight campaign in the Baltimore-Washington D.C. area in July 2011. The ACAM, flown on board the NASA UC-12 aircraft, includes two spectrographs covering the spectral region 304-900 nm and a high-definition video camera, and is expected to provide column measurements of several important air quality trace gases and aerosols for the DISCOVER-AQ mission. The quick look results for NO2 have been shown to very useful in capturing the strong spatiotemporal variability of NO2. Preliminary fitting of UV/Visible spectra has shown that ACAM measurements have adequate signal to noise ratio to measure the trace gases O2, NO2, HCHO, and maybe SO2 and CHOCHO, at individual pixel resolution, although a great deal of effort is needed to improve the instrument calibration and derive proper reference spectrum for retrieving absolute trace gas column densities. In this study, we present analysis of ACAM instrument calibration including slit function, wavelength registration, and radiometric calibration for both nadir-viewing and zenith-sky measurements. Based on this analysis, an irradiance reference spectrum at ACAM resolution will be derived from a high-resolution reference spectrum with additional correction to account for instrument calibration. Using the derived reference spectrum and/or the measured zenith sky measurements, we will perform non-linear least squares fitting to investigate the retrievals of slant column densities of these trace gases from ACAM measurements, and also use an optimal estimation based algorithm including full radiative transfer calculations to derive the vertical column densities of these trace gases. The initial results will be compared with available in-situ and ground-based measurements taken during the DISCOVER-AQ campaign.

Emissions of trace gases from Australian temperate forest fires: emission factors and dependence on modified combustion efficiency

NASA Astrophysics Data System (ADS)

Guérette, Elise-Andrée; Paton-Walsh, Clare; Desservettaz, Maximilien; Smith, Thomas E. L.; Volkova, Liubov; Weston, Christopher J.; Meyer, Carl P.

2018-03-01

We characterised trace gas emissions from Australian temperate forest fires through a mixture of open-path Fourier transform infrared (OP-FTIR) measurements and selective ion flow tube mass spectrometry (SIFT-MS) and White cell FTIR analysis of grab samples. We report emission factors for a total of 25 trace gas species measured in smoke from nine prescribed fires. We find significant dependence on modified combustion efficiency (MCE) for some species, although regional differences indicate that the use of MCE as a proxy may be limited. We also find that the fire-integrated MCE values derived from our in situ on-the-ground open-path measurements are not significantly different from those reported for airborne measurements of smoke from fires in the same ecosystem. We then compare our average emission factors to those measured for temperate forest fires elsewhere (North America) and for fires in another dominant Australian ecosystem (savanna) and find significant differences in both cases. Indeed, we find that although the emission factors of some species agree within 20 %, including those of hydrogen cyanide, ethene, methanol, formaldehyde and 1,3-butadiene, others, such as acetic acid, ethanol, monoterpenes, ammonia, acetonitrile and pyrrole, differ by a factor of 2 or more. This indicates that the use of ecosystem-specific emission factors is warranted for applications involving emissions from Australian forest fires.

Extraterrestrial amino acids in Orgueil and Ivuna: Tracing the parent body of CI type carbonaceous chondrites

PubMed Central

Ehrenfreund, Pascale; Glavin, Daniel P.; Botta, Oliver; Cooper, George; Bada, Jeffrey L.

2001-01-01

Amino acid analyses using HPLC of pristine interior pieces of the CI carbonaceous chondrites Orgueil and Ivuna have found that β-alanine, glycine, and γ-amino-n-butyric acid (ABA) are the most abundant amino acids in these two meteorites, with concentrations ranging from ≈600 to 2,000 parts per billion (ppb). Other α-amino acids such as alanine, α-ABA, α-aminoisobutyric acid (AIB), and isovaline are present only in trace amounts (<200 ppb). Carbon isotopic measurements of β-alanine and glycine and the presence of racemic (D/L ≈ 1) alanine and β-ABA in Orgueil suggest that these amino acids are extraterrestrial in origin. In comparison to the CM carbonaceous chondrites Murchison and Murray, the amino acid composition of the CIs is strikingly distinct, suggesting that these meteorites came from a different type of parent body, possibly an extinct comet, than did the CM carbonaceous chondrites. PMID:11226205

TRACE GAS CONCENTRATIONS IN SMALL STREAMS OF THE GEORGIA PIEDMONT

EPA Science Inventory

Seventeen headwater watersheds within the SFBR watershed ranging from 0.5 to 3.4 km2 were selected. We have been monitoring concentrations of the trace gases nitrous oxide, methane, and carbon dioxide, and other parameters (T, conductivity, dissolved oxygen, pH, nutrients, flow r...

Scavenging of radioactive soluble gases from inhomogeneous atmosphere by evaporating rain droplets.

PubMed

Elperin, Tov; Fominykh, Andrew; Krasovitov, Boris

2015-05-01

We analyze effects of inhomogeneous concentration and temperature distributions in the atmosphere, rain droplet evaporation and radioactive decay of soluble gases on the rate of trace gas scavenging by rain. We employ a one-dimensional model of precipitation scavenging of radioactive soluble gaseous pollutants that is valid for small gradients and non-uniform initial altitudinal distributions of temperature and concentration in the atmosphere. We assume that conditions of equilibrium evaporation of rain droplets are fulfilled. It is demonstrated that transient altitudinal distribution of concentration under the influence of rain is determined by the linear wave equation that describes propagation of a scavenging wave front. The obtained equation is solved by the method of characteristics. Scavenging coefficients are calculated for wet removal of gaseous iodine-131 and tritiated water vapor (HTO) for the exponential initial distribution of trace gases concentration in the atmosphere and linear temperature distribution. Theoretical predictions of the dependence of the magnitude of the scavenging coefficient on rain intensity for tritiated water vapor are in good agreement with the available atmospheric measurements. Copyright © 2015 Elsevier Ltd. All rights reserved.

Passive degassing at Nyiragongo (D.R. Congo) and Etna (Italy) volcanoes: the chemical characterization of the emissions and assessment of their uptake of trace elements emissions on the local environment

NASA Astrophysics Data System (ADS)

Calabrese, Sergio; Scaglione, Sarah; Milazzo, Silvia; D'Alessandro, Walter; Bobrowski, Nicole; Giuffrida, Giovanni; Tedesco, Dario; Parello, Francesco

2014-05-01

Volcanoes are well known as an impressive large natural source of trace elements into the troposphere. Among others, Etna (Italy) and Nyiragongo (D.R. Congo), two noteworthy emitters on Earth, are two stratovolcanoes located in different geological settings, both characterized by persistent passive degassing from their summit craters. Here, we present some results on trace element composition in volcanic plume emissions, atmospheric bulk deposition (rainwater) and their uptake of the surrounding vegetation, with the aim to compare and identify differences and similarities between this these two volcanoes. Volcanic emissions were sampled by using active filter-pack for acid gases (sulfur and halogens) and specific teflon filters for particulates (major and trace elements). The impact of the volcanogenic deposition in the surrounding of the crater rims was investigated by using different sampling techniques: bulk rain collectors gauges were used to collect atmospheric bulk deposition, and biomonitoring technique was carried out to collect gases and particulates by using endemic plant species. Concentrations of major and trace elements of volcanic plume emissions (gases and particulates) were obtained by elution and microwave digestion of the collected filters: sulfur and halogens were determined by ion chromatography and ICP-MS, and untreated filters for particulate were acid digested and analysed by ICP-OES and ICP-MS. Rain water and plant samples were also analysed for major and trace elements by using ICP-OES and ICP-MS. In total 55 elements were determined. The estimates of the trace element fluxes confirm that Etna and Nyiragongo are large sources of metals to the atmosphere, especially considering their persistent state of passive degassing. In general, chemical composition of the volcanic aerosol particles of both volcanoes is characterized by two main components: one is related to the silicic component produced by magma bursting and fragmentation, enriching

Volcanic Gases and Hot Spring Water to Evaluate the Volcanic Activity of the Mt. Baekdusan

NASA Astrophysics Data System (ADS)

Yun, S. H.; Lee, S.; Chang, C.

2017-12-01

This study performed the analysis on the volcanic gases and hot spring waters from the Julong hot spring at Mt. Baekdu, also known as Changbaishan on the North Korea(DPRK)-China border, during the period from July 2015 to August 2016. Also, we confirmed the errors that HCO3- concentrations of hot spring waters in the previous study (Lee et al. 2014) and tried to improve the problem. Dissolved CO2 in hot spring waters was analyzed using gas chromatograph in Lee et al.(2014). Improving this, from 2015, we used TOC-IC to analysis dissolved CO2. Also, we analyzed the Na2CO3 standard solutions of different concentrations using GC, and confirmed the correlation between the analytical concentrations and the real concentrations. However, because the analytical results of the Julong hot spring water were in discord with the estimated values based on this correlation, we can't estimate the HCO3-concentrations of 2014 samples. During the period of study, CO2/CH4 ratios in volcanic gases are gradually decreased, and this can be interpreted in two different ways. The first interpretation is that the conditions inside the volcanic edifice are changing into more reduction condition, and carbon in volcanic gases become more favorable to distribute into CH4 or CO than CO2. The second interpretation is that the interaction between volcanic gases and water becomes greater than past, and the concentrations of CO2which have much higher solubility in water decreased, relatively. In general, the effect of scrubbing of volcanic gas is strengthened during the quiet periods of volcanic activity rather than active periods. Meanwhile, the analysis of hot spring waters was done on the anion of acidic gases species, the major cations, and some trace elements (As, Cd, Re).This work was funded by the Korea Meteorological Administration Research and Development Program under Grant KMIPA 2015-3060.

Apparatus for purifying arsine, phosphine, ammonia, and inert gases to remove Lewis acid and oxidant impurities therefrom

DOEpatents

Tom, Glenn M.; Brown, Duncan W.

1991-01-08

An apparatus for purifying a gaseous mixture comprising arsine, phosphine, ammonia, and/or inert gases, to remove Lewis acid and/or oxidant impurities therefrom, comprising a vessel containing a bed of a scavenger, the scavenger including a support having associated therewith an anion which is effective to remove such impurities, such anion being selected from one or more members of the group consisting of: (i) carbanions whose corresponding protonated compounds have a pK.sub.a value of from about 22 to about 36; and (ii) anions formed by reaction of such carbanions with the primary component of the mixture.

Regenerable Incinerator Exhaust Purification and Trace Contaminant Control System

NASA Technical Reports Server (NTRS)

Finn, John E.; Cho, Shelia Y.; LeVan, M. Douglas

2003-01-01

In this novel approach to air purification, contaminants removed from a process air stream by a high-capacity adsorbent are displaced periodically by a warm, high-humidity, reverse-flow air stream. Displaced contaminants flow into a closed regeneration loop, in which organic compounds are oxidized catalytically and acid gases are removed by a gas- water contactor (which also serves as the source of the water vapor). These features are expected to result in a design that has few expendables and lower energy consumption than alternative regenerable techniques. The joint project between NASA Ames Research Center and Vanderbilt University has completed its third year. Breadboard development continues at NASA Ames, while Vanderbilt has completed most of its adsorption equilibria development. Vanderbilt has completed its fixed-bed apparatus for investigation of dynamic adsorption and desorption processes for trace organic compounds and water vapor, and is continuing its development of the mathematical model describing the column dynamics.

Stratospheric measurements of ozone-depleting substances and greenhouse gases using AirCores

NASA Astrophysics Data System (ADS)

Laube, Johannes; Leedham Elvidge, Emma; Kaiser, Jan; Sturges, Bill; Heikkinen, Pauli; Laurila, Tuomas; Hatakka, Juha; Kivi, Rigel; Chen, Huilin; Fraser, Paul; van der Veen, Carina; Röckmann, Thomas

2017-04-01

Retrieving air samples from the stratosphere has previously required aircraft or large balloons, both of which are expensive to operate. The novel "AirCore" technique (Karion et al., 2010) enables stratospheric sampling using weather balloons, which is much more cost effective. AirCores are long (up to 200 m) stainless steel tubes which are placed as a payload on a small balloon, can ascend to over 30 km and fill upon descent, collecting a vertical profile of the atmosphere. Retrieved volumes are much smaller though, which presents a challenge for trace gas analysis. To date, only the more abundant trace gases such as carnon dioxide (CO2) and methane (CH4) have been quantified in AirCores. Halogenated trace gases are also important greenhouse gases and many also deplete stratospheric ozone. Their concentrations are however much lower i.e. typically in the part per trillion (ppt) molar range. We here present the first stratospheric measurements of halocarbons in AirCores obtained using UEA's highly sensitive (detection limits of 0.01-0.1 ppt in 10 ml of air) gas chromatography mass spectrometry system. The analysed air originates from a Stratospheric Air Sub-sampler (Mrozek et al., 2016) which collects AirCore segments after the non-destructive CO2 and CH4 analysis. Successfully measured species include CFC-11, CFC-12, CFC-113, CFC-115, H-1211, H-1301, HCFC-22, HCFC-141b, HCFC-142b, HCFC-133a, and sulphur hexafluoride (SF6). We compare the observed mixing ratios and precisions with data obtained from samples collected during various high-altitude aircraft campaigns between 2009 and 2016 as well as with southern hemisphere tropospheric long-term trends. As part of the ERC-funded EXC3ITE (EXploring stratospheric Composition, Chemistry and Circulation with Innovative Techniques) project more than 40 AirCore flights are planned in the next 3 years with an expanded range of up to 30 gases in order to explore seasonal and interannual variability in the stratosphere

High temperature abatement of acid gases from waste incineration. Part II: Comparative life cycle assessment study

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

Biganzoli, Laura, E-mail: laura.biganzoli@mail.polimi.it; Racanella, Gaia; Marras, Roberto

Highlights: • Two scenarios of acid gases removal in WTE plants were compared in an LCA study. • A detailed inventory based on primary data has been reported for the production of the new dolomitic sorbent. • Results show that the comparison between the two scenarios does not show systematic differences. • The potential impacts are reduced only if there is an increase in the energy efficiency of the WTE plant. - Abstract: The performances of a new dolomitic sorbent, named Depurcal®MG, to be directly injected at high temperature in the combustion chamber of Waste-To-Energy (WTE) plants as a preliminarymore » stage of deacidification, were experimentally tested during full-scale commercial operation. Results of the experimentations were promising, and have been extensively described in Biganzoli et al. (2014). This paper reports the Life Cycle Assessment (LCA) study performed to compare the traditional operation of the plants, based on the sole sodium bicarbonate feeding at low temperature, with the new one, where the dolomitic sorbent is injected at high temperature. In the latter the sodium bicarbonate is still used, but at lower rate because of the decreased load of acid gases entering the flue gas treatment line. The major goal of the LCA was to make sure that a burden shifting was not taking place somewhere in the life cycle stages, as it might be the case when a new material is used in substitution of another one. According to the comparative approach, only the processes which differ between the two operational modes were included in the system boundaries. They are the production of the two reactants and the treatment of the corresponding solid residues arising from the neutralisation of acid gases. The additional CO{sub 2} emission at the stack of the WTE plant due to the activation of the sodium bicarbonate was also included in the calculation. Data used in the modelling of the foreground system are primary, derived from the experimental tests

Aerosol optical properties and trace gas emissions by PAX and OP-FTIR for laboratory-simulated western US wildfires during FIREX

NASA Astrophysics Data System (ADS)

Selimovic, Vanessa; Yokelson, Robert J.; Warneke, Carsten; Roberts, James M.; de Gouw, Joost; Reardon, James; Griffith, David W. T.

2018-03-01

for species rarely or not yet measured in the field. For instance, the OP-FTIR data alone show that ammonia (1.62 g kg-1), acetic acid (2.41 g kg-1), nitrous acid (HONO, 0.61 g kg-1), and other trace gases such as glycolaldehyde (0.90 g kg-1) and formic acid (0.36 g kg-1) are significant emissions that were poorly characterized or not characterized for US wildfires in previous work. The PAX measurements show that the ratio of brown carbon (BrC) absorption to BC absorption is strongly dependent on modified combustion efficiency (MCE) and that BrC absorption is most dominant for combustion of duff (AAE 7.13) and rotten wood (AAE 4.60): fuels that are consumed in greater amounts during wildfires than prescribed fires. Coupling our laboratory data with field data suggests that fresh wildfire smoke typically has an EF for BC near 0.2 g kg-1, an SSA of ˜ 0.91, and an AAE of ˜ 3.50, with the latter implying that about 86 % of the aerosol absorption at 401 nm is due to BrC.

Study of different operational modes of the IAP 2-port-DOAS instrument for atmospheric trace gases investigation during CINDI-2 campaign basing on residual noise analysis

NASA Astrophysics Data System (ADS)

Borovski, A.; Postylyakov, O.; Elokhov, A.; Bruchkovski, I.

2017-11-01

An instrument for measuring atmospheric trace gases by DOAS method using scattered solar radiation was developed in A.M.Obukhov IAP RAS. The instrument layout is based on the lab Shamrock 303i spectrograph supplemented by 2-port radiation input system employing optical fiber. Optical ports may be used with a telescope with fixed field of view or with a scanning MAX-DOAS unit. MAX-DOAS unit port will be used for investigation of gas contents and profiles in the low troposphere. In September 2016 the IAP instrument participated in the CINDI-2 campaign, held in the Netherlands. CINDI 2 (2nd Cabauw Intercomparison of Nitrogen Dioxide Measuring Instruments) involves about 40 instruments quasi-synchronously performing DOAS measurements of NO2 and other trace gases. During the campaign the instrument ports had telescopes A and B with similar field of view of about 0.3°. Telescope A was always directed to the zenith. Telescope B was directed at 5° elevation angle. Two gratings were installed in the spectrometer. They provide different spectral resolution (FWHM 0.4 and 0.8 nm respectively) and spectral window width ( 70 and 140 nm respectively). During CINDI-2 campaign we performed test measurements in UV and visible wavelength ranges to investigate instrument stability and retrieval errors of NO2 and HCHO contents. We perform the preliminary error analysis of retrieval of the NO2 and HCHO differential slant column densities using spectra measured in four modes of the instrument basing on residual noise analysis in this paper. It was found that rotation of grating turret does not significantly affected on quality of NO2 DSCD retrieval from spectra which measured in visible spectral region. Influence of grating turret rotation is much more significant for gas DSCD retrieval from spectra which measured in UV spectral region. Standard deviation of retrieval error points to presence of some systematic error.

Evolution of Gases and Particles from a Savanna Fire in South Africa

NASA Technical Reports Server (NTRS)

Hobbs, Peter V.; Sinha, Parikhit; Yokelson, Robert J.; Christian, Ted J.; Blake, Donald R.; Gao, Song; Kirchstetter, Thomas W.; Novakov, Tica; Pilewskie, Peter

2003-01-01

Airborne measurements of particles and gases fiom a 1000-ha savanna fire in South Africa are presented. These measurements represent the most extensive data set reported on the aging of biomass smoke. The measurements include total concentrations of particles (CN), particle sizes, particulate organic carbon and black carbon, light-scattering coefficients, downwelling UV fluxes, and mixing ratios for 42 trace gases and 7 particulate species. The ratios of excess nitrate, ozone, and gaseous acetic acid to excess CO increased significantly as the smoke aged over approximately 40-45 min, indicating that these species were formed by photochemistry in the plume. For 17 other species, the excess mixing ratio normalized by the excess mixing ratio of CO decreased significantly with ' smoke age. The relative rates of decrease for a number of chemical species imply that the average OH concentration in the plume was approximately 1.7 x l0(exp 7) molecules /cubic centimeter. Excess CN, normalized by excess CO, decreased rapidly during the first approximately 5 min of aging, probably due to coagulation, and then increased, probably due to gas-to-particle conversion. The CO-normalized concentrations of particles < 1.5 microns in diameter decreased, and particles >1.5 micron diameter increased, with smoke age. The spectral depletion of solar radiation by the smoke is depicted. The downwelling UV flux near the vertical center of the plume was about two-thirds of that near the top of the plume.

Applications of broadband cavity enhanced spectroscopy for measurements of trace gases and aerosols

NASA Astrophysics Data System (ADS)

Washenfelder, R. A.; Attwood, A. R.; Brock, C. A.; Brown, S. S.; Dube, W. P.; Flores, J. M.; Langford, A. O.; Min, K. E.; Rudich, Y.; Stutz, J.; Wagner, N.; Young, C.; Zarzana, K. J.

2015-12-01

Broadband cavity enhanced spectroscopy (BBCES) uses a broadband light source, optical cavity, and multichannel detector to measure light extinction with high sensitivity. This method differs from cavity ringdown spectroscopy, because it uses an inexpensive, incoherent light source and allows optical extinction to be determined simultaneously across a broad wavelength region.Spectral fitting methods can be used to retrieve multiple absorbers across the observed wavelength region. We have successfully used this method to measure glyoxal (CHOCHO), nitrous acid (HONO), and nitrogen dioxide (NO2) from ground-based and aircraft-based sampling platforms. The detection limit (2-sigma) in 5 s for retrievals of CHOCHO, HONO and NO2 is 32, 250 and 80 parts per trillion (pptv).Alternatively, gas-phase absorbers can be chemically removed to allow the accurate determination of aerosol extinction. In the laboratory, we have used the aerosol extinction measurements to determine scattering and absorption as a function of wavelength. We have deployed a ground-based field instrument to measure aerosol extinction, with a detection limit of approximately 0.2 Mm-1 in 1 min.BBCES methods are most widely used in the near-ultraviolet and visible spectral region. Recently, we have demonstrated measurements at 315-350 nm for formaldehyde (CH2O) and NO2. Extending the technique further into the ultraviolet spectral region will allow important additional measurements of trace gas species and aerosol extinction.

Miniaturized Laser Heterodyne Radiometer (LHR) for Measurements of Greenhouse Gases in the Atmospheric Column

NASA Technical Reports Server (NTRS)

Steel, Emily; McLinden, Matthew

2012-01-01

This passive laser heterodyne radiometer (LHR) instrument simultaneously measures multiple trace gases in the atmospheric column including carbon dioxide (CO2) and methane (CH4), and resolves their concentrations at different altitudes. This instrument has been designed to operate in tandem with the passive aerosol sensor currently used in AERONET (an established network of more than 450 ground aerosol monitoring instruments worldwide). Because aerosols induce a radiative effect that influences terrestrial carbon exchange, simultaneous detection of aerosols with these key carbon cycle gases offers a uniquely comprehensive measurement approach. Laser heterodyne radiometry is a technique for detecting weak signals that was adapted from radio receiver technology. In a radio receiver, a weak input signal from a radio antenna is mixed with a stronger local oscillator signal. The mixed signal (beat note, or intermediate frequency) has a frequency equal to the difference between the input signal and the local oscillator. The intermediate frequency is amplified and sent to a detector that extracts the audio from the signal. In the LHR instrument described here, sunlight that has undergone absorption by the trace gas is mixed with laser light at a frequency matched to a trace gas absorption feature in the infrared (IR). Mixing results in a beat signal in the RF (radio frequency) region that can be related to the atmospheric concentration. For a one-second integration, the estimated column sensitivities are 0.1 ppmv for CO2, and <1 ppbv for CH4. In addition to producing a standalone ground measurement product, this instrument could be used to calibrate/validate four Earth observing missions: ASCENDS (Active Sensing of CO2 Emissions over Nights, Days, and Seasons), OCO-2 (Orbiting Carbon Observatory), OCO-3, and GOSAT (Greenhouse gases Observational SATellite). The only network that currently measures CO2 and CH4 in the atmospheric column is TCCON (Total Carbon Column

Analysis of Trace Gas Mixtures Using an External Cavity Quantum Cascade Laser Sensor

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

Phillips, Mark C.; Taubman, Matthew S.; Brumfield, Brian E.

2015-07-01

We measure and analyze mixtures of trace gases at ppb-ppm levels using an external cavity quantum cascade laser sensor with a 1-second response time. Accurate spectral fits are obtained in the presence of overlapping spectra.

Migration of 18 trace elements from ceramic food contact material: influence of pigment, pH, nature of acid and temperature.

PubMed

Demont, M; Boutakhrit, K; Fekete, V; Bolle, F; Van Loco, J

2012-03-01

The effect of pH, nature of acid and temperature on trace element migration from ceramic ware treated with 18 commercially available glazes was studied. Besides of the well-studied lead and cadmium, migration of other toxic and non toxic elements such as aluminum, boron, barium, cobalt, chrome, copper, iron, lithium, magnesium, manganese, nickel, antimony, tin, strontium, titanium, vanadium, zinc and zirconium was investigated in order to evaluate their potential health hazards. Trace element concentrations were determined with Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). This study suggests that there is indeed a health risk concerning the possible migration of other elements than lead and cadmium. At low pH (2acid plays an important role. Citric and malic acid seem to be more aggressive to the glaze than acetic acid except for aluminum, barium, chromium, iron and magnesium. The migration kinetics between pH 2 and 3 in acetic acid of these exceptions also are more exponential while the other elements display a decreasing linear gradient. In ceramics used for this study (fired at 900 °C), a linear relationship between the migration and the temperature was observed. Copyright © 2012 Elsevier Ltd. All rights reserved.

[Emission and control of gases and odorous substances from animal housing and manure depots].

PubMed

Hartung, J

1992-02-01

Agricultural animal production in increasingly regarded as a source of gases which are both aggravating and ecologically harmful. An overview of the origin, number and quantity of trace gases emitted from animal housing and from manure stores is presented and possible means of preventing or reducing them are discussed. Of the 136 trace gases in the air of animal houses, odorous substances, ammonia and methane are most relevant to the environment. The role played by the remaining gases is largely unknown. Quantitative information is available for 23 gases. The gases are emitted principally from freshly deposited and stored faeces, from animal feed and from the animals themselves. Future work should determine sources and quantities of the gases emitted from animal housing more precisely and should aim to investigate the potential of these gases to cause damage in man, animals and environment. Odorous substances have an effect on the area immediately surrounding the animal housing. They can lead to considerable aggravation in humans. For years, VDI1 guidelines (3471/72), which prescribe distances between residential buildings and animal housing, have been valuable in preventing odour problems of this kind. Coverings are suitable for outside stores. The intensity of the odour from animal housing waste air increases from cattle through to hens and pigs; it is also further affected by the type of housing, the age of the animals and the purpose for which they are being kept. Methods of cleaning waste air (scrubbers/biofilters) are available for problematic cases. The need for guidelines to limit emissions from individual outside manure stores (lagoons) is recognised. Total ammonia emissions from animal production in the Federal Republic of Germany (up to 1989) are estimated at approximately 300,000 to 600,000 t/year. There is a shortage of satisfactory and precise research on the extent of emissions, in particular on those from naturally ventilated housing. It is

Trace metals in upland headwater lakes in Ireland.

PubMed

Burton, Andrew; Aherne, Julian; Hassan, Nouri

2013-10-01

Trace elements (n = 23) in Irish headwater lakes (n = 126) were investigated to determine their ambient concentrations, fractionation (total, dissolved, and non-labile), and geochemical controls. Lakes were generally located in remote upland, acid-sensitive regions along the coastal margins of the country. Total trace metal concentrations were low, within the range of natural pristine surface waters; however, some lakes (~20 %) had inorganic labile aluminum and manganese at levels potentially harmful to aquatic organisms. Redundancy analysis indicated that geochemical weathering was the dominant controlling factor for total metals, compared with acidity for dissolved metals. In addition, many metals were positively correlated with dissolved organic carbon indicating their affinity (or complexation) with humic substances (e.g., aluminum, iron, mercury, lead). However, a number of trace metals (e.g., aluminum, mercury, zinc) were correlated with anthropogenic acidic deposition (i.e., non-marine sulfate), suggesting atmospheric sources or elevated leaching owing to acidic deposition. As transboundary air pollution continues to decline, significant changes in the cycling of trace metals is anticipated.

Characterization of atmospheric trace gases and particulate matter in Hangzhou, China

NASA Astrophysics Data System (ADS)

Zhang, Gen; Xu, Honghui; Qi, Bing; Du, Rongguang; Gui, Ke; Wang, Hongli; Jiang, Wanting; Liang, Linlin; Xu, Wanyun

2018-02-01

The Yangtze River Delta (YRD) is one of the most densely populated regions in China with severe air quality issues that have not been fully understood. Thus, in this study, based on 1-year (2013) continuous measurement at a National Reference Climatological Station (NRCS, 30.22° N, 120.17° E; 41.7 m a.s.l.) in the center of Hangzhou in the YRD, we investigated the seasonal characteristics, interspecies relationships, and the local emissions and the regional potential source contributions of trace gases (including O3, NOx, NOy, SO2, and CO) and particulate matter (PM2.5 and PM10). Results revealed that severe two-tier air pollution (photochemical and haze pollution) occurred in this region, with frequent exceedances in O3 (38 days) and PM2.5 (62 days). O3 and PM2.5 both exhibited distinct seasonal variations with reversed patterns: O3 reaching a maximum in warm seasons (May and July) but PM2.5 reaching a maximum in cold seasons (November to January). The overall results from interspecies correlation indicated a strong local photochemistry favoring the O3 production under a volatile organic compound (VOC)-limited regime, whereas it moved towards an optimum O3 production zone during warm seasons, accompanied by the formation of secondary fine particulates under high O3. The emission maps of PM2.5, CO, NOx, and SO2 demonstrated that local emissions were significant for these species on a seasonal scale. The contributions from the regional transport among inland cities (Zhejiang, Jiangsu, Anhui, and Jiangxi Province) on a seasonal scale were further confirmed to be crucial to air pollution at the NRCS site by using backward trajectory simulations. Air masses transported from the offshore areas of the Yellow Sea, East Sea, and South Sea were also found to be highly relevant to the elevated O3 at the NRCS site through the analysis of potential source contribution function (PSCF). Case studies of photochemical pollution (O3) and haze (PM2.5) episodes both suggested the

Emission factors of fine particles, carbonaceous aerosols and traces gases from road vehicles: Recent tests in an urban tunnel in the Pearl River Delta, China

NASA Astrophysics Data System (ADS)

Zhang, Yanli; Wang, Xinming; Li, Guanghui; Yang, Weiqiang; Huang, Zhonghui; Zhang, Zhou; Huang, Xinyu; Deng, Wei; Liu, Tengyu; Huang, Zuzhao; Zhang, Zhanyi

2015-12-01

Motor vehicles contribute primarily and secondarily to air quality problems due to fine particle (PM2.5) and ozone (O3) pollution in China's megacities. Characterizing vehicle emission with the rapid change of vehicle numbers and fleet compositions is vital for both bottom-up emission survey and top-down source apportioning. To obtain emission factors (EFs) of PM2.5, carbonaceous aerosols and trace gases for road vehicles, in urban Guangzhou we conducted a field campaign in 2014 in the Zhujiang Tunnel, a heavily burdened tunnel with about 40,000 motor vehicles passing through each of its two separated bores per day. PM2.5 and volatile organic compounds (VOCs) were sampled for offline analysis while trace gases including SO2, NOx and CO were measured online and in situ. An eddy covariance system with an integrated 3-D sonic anemometer was also adopted to measure CO2 and winds inside the tunnel. We recorded an average fleet composition of 61% light-duty gasoline vehicles (LDVs) + 12% heavy-duty diesel vehicles (HDVs) + 27% liquefied petroleum gas vehicles (LPGVs), and EFs of 82.7 ± 28.3, 19.3 ± 4.7 and 13.3 ± 3.3 mg veh-1 km-1, respectively, for PM2.5, organic carbon (OC) and elemental carbon (EC). These EFs were respectively 23.4%, 18.3% and 72.3% lower when compared to that measured in the same tunnel in 2004. EFs of PM2.5, OC and EC were higher at night time (148 ± 126, 29 ± 24 and 21 ± 18 mg veh-1 km-1, respectively) due to significantly elevated fractions of HDVs in the traffic fleets. An average ratio of OC to EC 1.45 from this tunnel study was much higher than that of ∼0.5 in previous tunnel studies. The EFs of SO2, NOx, CO, CO2 and NMHCs for road traffic were also obtained from our tunnel tests, and they were 20.7 ± 2.9, (1.29 ± 0.2)E+03, (3.10 ± 0.68)E+03, (3.90 ± 0.49)E+05, and 448 ± 39 mg veh-1 km-1, respectively.

The Influence of Trace Gases Absorption on Differential Ring Cross Sections

NASA Astrophysics Data System (ADS)

Han, Dong; Zhao, Keyi

2017-04-01

The Ring effect refers to the filling in of Fraunhofer lines, which is known as solar absorption lines, caused almost entirely by rotational Raman scattering. The rotational Raman scattering by N2 and O2 in the atmosphere is the main factor that leads to Ring effect. The Ring effect is one significant limitation to the accuracy of the retrieval of trace gas constituents in atmosphere, while using satellite data with Differential Optical Absorption Spectroscopy technique. In this study, firstly the solar spectrum is convolved with rotational Raman cross sections of atmosphere, which is calculated with rotational Raman cross sections of N2 and O2, divided by the original solar spectrum, with a cubic polynomial subtracted off, to create differential Ring spectrum Ring1. Secondly, the Ring effect for pure Raman scattering of the Fraunhofer spectrum plus the contribution from interference by terrestrial absorption which always comes from a kind of trace gas (e.g., O3) are derived. To allow for more generality, the optically thin term as well as the next term in the expansion for the Beer-Lambert law are calculated.Ring1, Ring2, and Ring3are the Fraunhofer only, 1st terrestrial correction, and 2nd terrestrial correction for DOAS fitting.

Trace gas emissions from burning Florida wetlands

NASA Technical Reports Server (NTRS)

Cofer, Wesley R., III; Levine, Joel S.; Lebel, Peter J.; Winstead, Edward L.; Koller, Albert M., Jr.; Hinkle, C. Ross

1990-01-01

Measurements of biomass burn-produced trace gases were obtained using a helicopter at low altitudes above burning Florida wetlands on November 9, 1987, and from both helicopter and light-aircraft samplings on November 7, 1988. Carbon dioxide normalized emission ratios for carbon monoxide, hydrogen, methane, total nonmethane hydrocarbons, and nitrous oxide were obtained over burning graminoid wetlands consisting primarily of Spartina bakeri and Juncus roemerianus. Some interspersed scrub oak and saw palmetto were also burned. No significant differences were observed in the emission ratios determined for these gases from samples collected over flaming, mixed, and smoldering phases of combustion during the 1987 fire. Combustion-categorized differences in emission ratios were small for the 1988 fire. Combustion efficiency was relatively good (low emission ratios for reduced gases) for both fires. It is believed that the consistently low emission ratios were a unique result of graminoid wetlands fires, in which the grasses and rushes burned rapidly down to standing water and were quickly extinguished. Consequently, the efficiency of the combustion was good and the amount and duration of smoldering combustion was greatly deminished.

Process for recovery of sulfur from acid gases

DOEpatents

Towler, Gavin P.; Lynn, Scott

1995-01-01

Elemental sulfur is recovered from the H.sub.2 S present in gases derived from fossil fuels by heating the H.sub.2 S with CO.sub.2 in a high-temperature reactor in the presence of a catalyst selected as one which enhances the thermal dissociation of H.sub.2 S to H.sub.2 and S.sub.2. The equilibrium of the thermal decomposition of H.sub.2 S is shifted by the equilibration of the water-gas-shift reaction so as to favor elemental sulfur formation. The primary products of the overall reaction are S.sub.2, CO, H.sub.2 and H.sub.2 O. Small amounts of COS, SO.sub.2 and CS.sub.2 may also form. Rapid quenching of the reaction mixture results in a substantial increase in the efficiency of the conversion of H.sub.2 S to elemental sulfur. Plant economy is further advanced by treating the product gases to remove byproduct carbonyl sulfide by hydrolysis, which converts the COS back to CO.sub.2 and H.sub.2 S. Unreacted CO.sub.2 and H.sub.2 S are removed from the product gas and recycled to the reactor, leaving a gas consisting chiefly of H.sub.2 and CO, which has value either as a fuel or as a chemical feedstock and recovers the hydrogen value from the H.sub.2 S.

Canonical partition functions: ideal quantum gases, interacting classical gases, and interacting quantum gases

NASA Astrophysics Data System (ADS)

Zhou, Chi-Chun; Dai, Wu-Sheng

2018-02-01

In statistical mechanics, for a system with a fixed number of particles, e.g. a finite-size system, strictly speaking, the thermodynamic quantity needs to be calculated in the canonical ensemble. Nevertheless, the calculation of the canonical partition function is difficult. In this paper, based on the mathematical theory of the symmetric function, we suggest a method for the calculation of the canonical partition function of ideal quantum gases, including ideal Bose, Fermi, and Gentile gases. Moreover, we express the canonical partition functions of interacting classical and quantum gases given by the classical and quantum cluster expansion methods in terms of the Bell polynomial in mathematics. The virial coefficients of ideal Bose, Fermi, and Gentile gases are calculated from the exact canonical partition function. The virial coefficients of interacting classical and quantum gases are calculated from the canonical partition function by using the expansion of the Bell polynomial, rather than calculated from the grand canonical potential.

Generalized Forchheimer Flows of Isentropic Gases

NASA Astrophysics Data System (ADS)

Celik, Emine; Hoang, Luan; Kieu, Thinh

2018-03-01

We consider generalized Forchheimer flows of either isentropic gases or slightly compressible fluids in porous media. By using Muskat's and Ward's general form of the Forchheimer equations, we describe the fluid dynamics by a doubly nonlinear parabolic equation for the appropriately defined pseudo-pressure. The volumetric flux boundary condition is converted to a time-dependent Robin-type boundary condition for this pseudo-pressure. We study the corresponding initial boundary value problem, and estimate the L^∞ and W^{1,2-a} (with 0trace theorem and an appropriate modification of Moser's iteration.

Observations of tropospheric trace gases and meteorology in rural Virginia using an unattended monitoring system: Hurricane Hugo (1989), A case study

NASA Astrophysics Data System (ADS)

Doddridge, Bruce G.; Dickerson, Russell R.; Holland, Joshua Z.; Cooper, James N.; Wardell, R. Glenn; Poulida, Olga; Watkins, James G.

1991-05-01

Tropospheric trace gases such as ozone and reactive nitrogen compounds exert a strong influence on global climate, but observations of these species are limited by the necessity of having a trained observer on site to monitor instruments. A technique using modern communications technology has been developed to transport and review data collected at a remote site. The site was equipped with a PAM II station and satellite data link so that raw, real-time data and equipment status were available for inspection readily on a workstation at the University of Maryland campus through a combination of wide and local area networks. CO, NO, NOy, O3, UV radiative flux, and meteorological parameters were measured in rural Virginia for a full year. The cleanest air observed over the year was associated with the passage of Hurricane Hugo over the mid-Atlantic region on September 22, 1989. Hourly average data for concentrations of CO, NOy, and O3 observed during this particular case study were as low as 90 ppbv, 570 pptv, and 11 ppbv, respectively. Within this period, daytime NO was highly variable, ranging between the detection limit of the instrument, ˜ 20 pptv, and 2.4 ppbv. These concentrations are well below the hourly concentration average at this site for these species during September 1989. Equivalent potential temperature, θe, in conjunction with the trace gas concentrations and geostrophic back-trajectories, illustrates how this hurricane influenced air parcel history; observed concentrations of CO and NOy increased with the time the air parcel spent over land. Observations at this site were consistent with current hurricane models based on mean soundings and aircraft flights. Hurricanes over land also appear to redistribute air vertically throughout the troposphere, creating the potential for substantial post-storm tropospheric column O3 increase.

Interannual variability of trace gases in the subtropical winter stratosphere

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

Gray, L.J.; Russell, J.M. III

1999-04-01

Measurements of water vapor and methane from the Halogen Occultation Experiment instrument on board the Upper Atmosphere Research Satellite are used to study the interannual variability of trace gas distributions in the atmosphere. Particular attention is paid to the mechanisms influencing trace gas distributions in the subtropics. The study highlights the quasi-biennial oscillation (QBO) dependence of subtropical tracer distributions more clearly than in previous studies. There is a strong correlation between the equatorial wind QBO and the slope of the tracer isolines in the Northern Hemisphere subtropics, with steeper subtropical isoline slopes in the easterly phase compared with the westerlymore » phase. This is particularly so in the lower stratosphere. Two possible mechanisms for the QBO signal in subtropical isoline slopes are identified: advection by the mean circulation and isentropic mixing. A comparison between the QBO signal in the slope of the tracer isolines and the isentropic tracer gradients is proposed as a method of determining which process is dominant. The authors suggest that the behavior of these two data diagnostics provides a stringent constraint on computer models of the atmosphere. On the basis of these diagnostics three height regions of the subtropical atmosphere are identified. (1) Below 450--500 K isentropic mixing associated with tropospheric disturbances penetrating the lower stratosphere is dominant. (2) In the region 500--750 K the data suggest that advection by the mean meridional circulation is important and that the role of isentropic mixing by eddies is relatively small. (3) Above 750 K isentropic mixing becomes increasingly important with height, and both advection and mixing are influential in determining the subtropical tracer distributions.« less

Fourier Transform Spectroscopy of two trace gases namely Methane and Carbon monoxide for planetary and atmospheric research application

NASA Astrophysics Data System (ADS)

Hashemi, R.; Dudaryonok, A. S.; Lavrentieva, N. N.; Vandaele, A. C.; Vander Auwera, J.; Tyuterev, AV Nikitin G., VI; Sung, K.; Smith, M. A. H.; Devi, V. M.; Predoi-Cross, A.

2017-02-01

Two atmospheric trace gases, namely methane and carbon monoxide have been considered in this study. Fourier transform absorption spectra of the 2-0 band of 12C16O mixed with CO2 have been recorded at total pressures from 156 to 1212 hPa and at 4 different temperatures between 240 K and 283 K. CO2 pressure-induced line broadening and line shift coefficients, and the associated temperature dependence have been measured in an multi-spectrum non-linear least squares analysis using Voigt profiles with an asymmetric profile due to line mixing. The measured CO2-broadening and CO2-shift parameters were compared with theoretical values, calculated by collaborators. In addition, the CO2-broadening and shift coefficients have been calculated for individual temperatures using the Exponential Power Gap (EPG) semi-empirical method. We also discuss the retrieved line shape parameters for Methane transitions in the spectral range known as the Methane Octad. We used high resolution spectra of pure methane and of dilute mixtures of methane in dry air, recorded with high signal to noise ratio at temperatures between 148 K and room temperature using the Bruker IFS 125 HR Fourier transform spectrometer (FTS) at the Jet Propulsion Laboratory, Pasadena, California. Theoretical calculations for line parameters have been performed and the results are compared with the previously published values and with the line parameters available in the GEISA2015 [1] and HITRAN2012 [2] databases.

One year observations of atmospheric reactive gases (O3, CO, NOx, SO2) at Jang Bogo base in Terra Nova Bay, Antarctica

NASA Astrophysics Data System (ADS)

Siek Rhee, Tae; Seo, Sora

2016-04-01

Antarctica is a remote area surrounded by the Southern Ocean and far from the influence of human activities, giving us unique opportunity to investigate the background variation of trace gases which are sensitive to the human activities. Korean Antarctic base, Jang Bogo, was established as a unique permanent overwintering base in Terra Nova Bay in February, 2014. One year later, we installed a package of instruments to monitor atmospheric trace gases at the base, which includes long-lived greenhouse gases, CO2, CH4, and N2O, and reactive gases, O3, CO, NOx, and SO2. The atmospheric chemistry observatory, where these scientific instruments were installed, is located ca. 1 km far from the main building and power plant, minimizing the influence of pollution that may come from the operation of the base. Here we focus on the reactive gases measured in-situ at the base; O3 displays a typical seasonal variation with high in winter and low in summer with seasonal amplitude of ~18 ppb, CO was high in September at ~56 ppb, probably implying the invasion of lower latitude air mass with biomass burning, and low in late summer due to photochemical oxidation. NO did not show clear seasonal variation, but SO2 reveals larger values in summer than in winter. We will discuss potential atmospheric processes behind these first observations of reactive gases in Terra Nova Bay, Antarctica.

Graphene/dodecanol floating solidification microextraction for the preconcentration of trace levels of cinnamic acid derivatives in traditional Chinese medicines.

PubMed

Hu, Shuang; Yang, Xiao; Xue, Jiao; Chen, Xuan; Bai, Xiao-Hong; Yu, Zhi-Hui

2017-07-01

A novel graphene/dodecanol floating solidification microextraction followed by HPLC with diode-array detection has been developed to extract trace levels of four cinnamic acid derivatives in traditional Chinese medicines. Several parameters affecting the performance were investigated and optimized. Also, possible microextraction mechanism was analyzed and discussed. Under the optimum conditions (amount of graphene in dodecanol: 0.25 mg/mL; volume of extraction phase: 70 μL; pH of sample phase: 3; extraction time: 30   min; stirring rate: 1000 rpm; salt amount: 26.5% NaCl; volume of sample phase: 10 mL, and without dispersant addition), the enrichment factors of four cinnamic acid derivatives ranged from 26 to 112, the linear ranges were 1.0 × 10 -2 -10.0 μg/mL for caffeic acid, 1.3 × 10 -3 -1.9 μg/mL for p-hydroxycinnamic acid, 2.8 × 10 -3 -4.1 μg/mL for ferulic acid, and 2.7 × 10 -3 -4.1 μg/mL for cinnamic acid, with r 2 ≥ 0.9993. The detection limits were found to be in the range of 0.1-1.0 ng/mL, and satisfactory recoveries (92.5-111.2%) and precisions (RSDs 1.1-9.5%) were also achieved. The results showed that the approach is simple, effective and sensitive for the preconcentration and determination of trace levels of cinnamic acid derivatives in Chinese medicines. The proposed method was compared with conventional dodecanol floating solidification microextraction and other extraction methods. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of a liquid chromatography-tandem mass spectrometry method for quantitative analysis of trace d-amino acids.

PubMed

Nakano, Yosuke; Konya, Yutaka; Taniguchi, Moyu; Fukusaki, Eiichiro

2017-01-01

d-Amino acids have recently attracted much attention in various research fields including medical, clinical and food industry due to their important biological functions that differ from l-amino acid. Most chiral amino acid separation techniques require complicated derivatization procedures in order to achieve the desirable chromatographic behavior and detectability. Thus, the aim of this research is to develop a highly sensitive analytical method for the enantioseparation of chiral amino acids without any derivatization process using liquid chromatography-tandem mass spectrometry (LC-MS/MS). By optimizing MS/MS parameters, we established a quantification method that allowed the simultaneous analysis of 18 d-amino acids with high sensitivity and reproducibility. Additionally, we applied the method to food sample (vinegar) for the validation, and successfully quantified trace levels of d-amino acids in samples. These results demonstrated the applicability and feasibility of the LC-MS/MS method as a novel, effective tool for d-amino acid measurement in various biological samples. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Method development for liquid chromatographic/triple quadrupole mass spectrometric analysis of trace level perfluorocarboxylic acids in articles of commerce

EPA Science Inventory

An analytical method to identify and quantify trace levels of C5 to C12 perfluorocarboxylic acids (PFCAs) in articles of commerce (AOC) is developed and rigorously validated. Solid samples were extracted in methanol, and liquid samples were diluted with a solvent consisting of 60...

History of chemically and radiatively important atmospheric gases from the Advanced Global Atmospheric Gases Experiment (AGAGE)

NASA Astrophysics Data System (ADS)

Prinn, Ronald G.; Weiss, Ray F.; Arduini, Jgor; Arnold, Tim; Langley DeWitt, H.; Fraser, Paul J.; Ganesan, Anita L.; Gasore, Jimmy; Harth, Christina M.; Hermansen, Ove; Kim, Jooil; Krummel, Paul B.; Li, Shanlan; Loh, Zoë M.; Lunder, Chris R.; Maione, Michela; Manning, Alistair J.; Miller, Ben R.; Mitrevski, Blagoj; Mühle, Jens; O'Doherty, Simon; Park, Sunyoung; Reimann, Stefan; Rigby, Matt; Saito, Takuya; Salameh, Peter K.; Schmidt, Roland; Simmonds, Peter G.; Steele, L. Paul; Vollmer, Martin K.; Wang, Ray H.; Yao, Bo; Yokouchi, Yoko; Young, Dickon; Zhou, Lingxi

2018-06-01

trends of tropospheric hydroxyl radicals (OH) from the rates of destruction of atmospheric trichloroethane (CH3CCl3), HFCs, and HCFCs and estimates of their emissions; (5) to determine from atmospheric observations and estimates of their destruction rates the magnitudes and distributions by region of surface sources and sinks of all measured gases; (6) to provide accurate data on the global accumulation of many of these trace gases that are used to test the synoptic-, regional-, and global-scale circulations predicted by three-dimensional models; and (7) to provide global and regional measurements of methane, carbon monoxide, and molecular hydrogen and estimates of hydroxyl levels to test primary atmospheric oxidation pathways at midlatitudes and the tropics. Network Information and Data Repository: http://agage.mit.edu/data or http://cdiac.ess-dive.lbl.gov/ndps/alegage.html (https://doi.org/10.3334/CDIAC/atg.db1001).

Hydrophobic Catalysts For Removal Of NOx From Flue Gases

NASA Technical Reports Server (NTRS)

Sharma, Pramod K.; Hickey, Gregory S.; Voecks, Gerald E.

1995-01-01

Improved catalysts for removal of nitrogen oxides (NO and NO2) from combustion flue gases formulated as composites of vanadium pentoxide in carbon molecular sieves. Promotes highly efficient selective catalytic reduction of NOx at relatively low temperatures while not being adversely affected by presence of water vapor and sulfur oxide gases in flue gas. Apparatus utilizing catalyst of this type easily integrated into exhaust stream of power plant to remove nitrogen oxides, generated in combustion of fossil fuels and contribute to formation of acid rain and photochemical smog.

Investigation of mesoscale trace gas distributions across an Arctic tropopause fold affected by gravity wave activity

NASA Astrophysics Data System (ADS)

Woiwode, Wolfgang; Oelhaf, Hermann; Dörnbrack, Andreas; Bramberger, Martina; Diekmann, Christopher; Friedl-Vallon, Felix; Höpfner, Michael; Hoor, Peter; Johansson, Sören; Krause, Jens; Kunkel, Daniel; Orphal, Johannes; Preusse, Peter; Ruhnke, Roland; Schlage, Romy; Schröter, Jennifer; Sinnhuber, Björn-Martin; Ungermann, Jörn; Zahn, Andreas

2017-04-01

Tropopause folds are known of enabling efficient exchange of trace constituents between the stratosphere and troposphere. In particular, the modification of the vertical distributions of radiatively important H2O and other reactive trace gases associated with tropopause folds is relevant for accurate model simulations of the upper troposphere and lower stratosphere composition. During the POLSTRACC/GW-LCYCLE/SALSA flight on 12 January 2016, the HALO (High Altitude LOng range) aircraft crossed twice an extended tropopause fold in the vicinity of the Arctic polar vortex. At the same time, the ECMWF operational analysis shows that the meteorological scenario probed above Italy was accompanied by wide-spread gravity wave activity induced by north-westerly winds. Using high spectral resolution limb-observations by the GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) spectrometer aboard HALO and associated observations, we investigate the vertical distributions of H2O, O3, temperature, and associated parameters across the tropopause fold. In combination with a high-resolution simulation by the ICON-ART (ICOsahedral Nonhydrostatic- Aerosol and Reactive Trace gases) model, we search for indications for irreversible trace gas exchange between the stratosphere and troposphere and the potential influence of gravity waves.

Linking genes to ecosystem trace gas fluxes in a large-scale model system

NASA Astrophysics Data System (ADS)

Meredith, L. K.; Cueva, A.; Volkmann, T. H. M.; Sengupta, A.; Troch, P. A.

2017-12-01

Soil microorganisms mediate biogeochemical cycles through biosphere-atmosphere gas exchange with significant impact on atmospheric trace gas composition. Improving process-based understanding of these microbial populations and linking their genomic potential to the ecosystem-scale is a challenge, particularly in soil systems, which are heterogeneous in biodiversity, chemistry, and structure. In oligotrophic systems, such as the Landscape Evolution Observatory (LEO) at Biosphere 2, atmospheric trace gas scavenging may supply critical metabolic needs to microbial communities, thereby promoting tight linkages between microbial genomics and trace gas utilization. This large-scale model system of three initially homogenous and highly instrumented hillslopes facilitates high temporal resolution characterization of subsurface trace gas fluxes at hundreds of sampling points, making LEO an ideal location to study microbe-mediated trace gas fluxes from the gene to ecosystem scales. Specifically, we focus on the metabolism of ubiquitous atmospheric reduced trace gases hydrogen (H2), carbon monoxide (CO), and methane (CH4), which may have wide-reaching impacts on microbial community establishment, survival, and function. Additionally, microbial activity on LEO may facilitate weathering of the basalt matrix, which can be studied with trace gas measurements of carbonyl sulfide (COS/OCS) and carbon dioxide (O-isotopes in CO2), and presents an additional opportunity for gene to ecosystem study. This work will present initial measurements of this suite of trace gases to characterize soil microbial metabolic activity, as well as links between spatial and temporal variability of microbe-mediated trace gas fluxes in LEO and their relation to genomic-based characterization of microbial community structure (phylogenetic amplicons) and genetic potential (metagenomics). Results from the LEO model system will help build understanding of the importance of atmospheric inputs to

A versatile, refrigerant- and cryogen-free cryofocusing-thermodesorption unit for preconcentration of traces gases in air

NASA Astrophysics Data System (ADS)

Obersteiner, Florian; Bönisch, Harald; Keber, Timo; O'Doherty, Simon; Engel, Andreas

2016-10-01

We present a compact and versatile cryofocusing-thermodesorption unit, which we developed for quantitative analysis of halogenated trace gases in ambient air. Possible applications include aircraft-based in situ measurements, in situ monitoring and laboratory operation for the analysis of flask samples. Analytes are trapped on adsorptive material cooled by a Stirling cooler to low temperatures (e.g. -80 °C) and subsequently desorbed by rapid heating of the adsorptive material (e.g. +200 °C). The set-up involves neither the exchange of adsorption tubes nor any further condensation or refocusing steps. No moving parts are used that would require vacuum insulation. This allows for a simple and robust design. Reliable operation is ensured by the Stirling cooler, which neither contains a liquid refrigerant nor requires refilling a cryogen. At the same time, it allows for significantly lower adsorption temperatures compared to commonly used Peltier elements. We use gas chromatography - mass spectrometry (GC-MS) for separation and detection of the preconcentrated analytes after splitless injection. A substance boiling point range of approximately -80 to +150 °C and a substance mixing ratio range of less than 1 ppt (pmol mol-1) to more than 500 ppt in preconcentrated sample volumes of 0.1 to 10 L of ambient air is covered, depending on the application and its analytical demands. We present the instrumental design of the preconcentration unit and demonstrate capabilities and performance through the examination of analyte breakthrough during adsorption, repeatability of desorption and analyte residues in blank tests. Examples of application are taken from the analysis of flask samples collected at Mace Head Atmospheric Research Station in Ireland using our laboratory GC-MS instruments and by data obtained during a research flight with our in situ aircraft instrument GhOST-MS (Gas chromatograph for the Observation of Tracers - coupled with a Mass Spectrometer).

Report: EPA Needs an Oversight Program for Protocol Gases

EPA Pesticide Factsheets

Report #09-P-0235, September 16, 2009. We purchased 87 cylinders of EPA Protocol Gases and had NIST analyze each cylinder to determine whether the three gaseous mixtures contained in each cylinder met the Acid Rain Program’s accuracy criterion.

Aerosol Optical Properties and Trace Gas Emissions From Laboratory-Simulated Western US Wildfires

NASA Astrophysics Data System (ADS)

Selimovic, V.; Yokelson, R. J.; Warneke, C.; Roberts, J. M.; De Gouw, J. A.; Reardon, J.; Griffith, D. W. T.

2017-12-01

Western wildfires have a major impact on air quality in the US. In the fall of 2016, 107 fires were burned in the large-scale combustion facility at the US Forest Service Missoula Fire Sciences Laboratory as part of the Fire Influence on Regional and Global Environments Experiment (FIREX). Canopy, litter, duff, dead wood, and other fuels from various widespread coniferous and chaparral ecosystems were burned in combinations to represent relevant configurations in the field and as pure components to investigate the effects of individual fuels. The smoke emissions were characterized by a large suite of state-of-the-art instruments. In this study we report emission factor (EF, g compound emitted per kg fuel burned) measurements in fresh smoke of a diverse suite of critically-important trace gases measured by open-path Fourier transform infrared spectroscopy (OP-FTIR). We also report aerosol optical properties (absorption EF, single scattering albedo (SSA) and Ångström absorption exponent (AAE)) as well as black carbon (BC) EF measured by photoacoustic extinctiometers (PAX) at 870 and 401 nm. A careful comparison with available field measurements of wildfires confirms that representative data can be extracted from the lab fire data. The OP-FTIR data show that ammonia (1.65 g kg-1), acetic acid (2.44 g kg-1), and other trace gases are significant emissions not previously measured for US wildfires. The PAX measurements show that brown carbon (BrC) absorption is most dominant for combustion of duff (AAE 7.13) and rotten wood (AAE 4.60): fuels that are consumed in greater amounts during wildfires than prescribed fires. We confirm that about 86% of the aerosol absorption at 401 nm in typical fresh wildfire smoke is due to BrC.

Analysis of Asian Outflow over the Western Pacific using Observations from Trace-P

NASA Technical Reports Server (NTRS)

Jacob, Daniel J.

2004-01-01

Our analysis of the TRACE-P data focused on answering the following questions: 1) How do anthropogenic sources in Asia contribute to chemical outflow over the western Pacific in spring? 2) How does biomass burning in southeast Asia contribute to this outflow? 3) How can the TRACE-P observations be used to better quantify the sources of environmentally important gases in eastern Asia? Our strategy drew on a combination of data analysis and global 3-D modeling, as described below. We also contributed to the planning and execution of TRACE-P through service as mission scientist and by providing chemical model forecasts in the field.

Distributions of Polycyclic Aromatic Hydrocarbons, Aromatic Ketones, Carboxylic Acids, and Trace Metals in Arctic Aerosols: Long-Range Atmospheric Transport, Photochemical Degradation/Production at Polar Sunrise.

PubMed

Singh, Dharmendra Kumar; Kawamura, Kimitaka; Yanase, Ayako; Barrie, Leonard A

2017-08-15

The distributions, correlations, and source apportionment of aromatic acids, aromatic ketones, polycyclic aromatic hydrocarbons (PAHs), and trace metals were studied in Canadian high Arctic aerosols. Nineteen PAHs including minor sulfur-containing heterocyclic PAH (dibenzothiophene) and major 6 carcinogenic PAHs were detected with a high proportion of fluoranthene followed by benzo[k]fluoranthene, pyrene, and chrysene. However, in the sunlit period of spring, their concentrations significantly declined likely due to photochemical decomposition. During the polar sunrise from mid-March to mid-April, benzo[a]pyrene to benzo[e]pyrene ratios significantly dropped, and the ratios diminished further from late April to May onward. These results suggest that PAHs transported over the Arctic are subjected to strong photochemical degradation at polar sunrise. Although aromatic ketones decreased in spring, concentrations of some aromatic acids such as benzoic and phthalic acids increased during the course of polar sunrise, suggesting that aromatic hydrocarbons are oxidized to result in aromatic acids. However, PAHs do not act as the major source for low molecular weight (LMW) diacids such as oxalic acid that are largely formed at polar sunrise in the arctic atmosphere because PAHs are 1 to 2 orders of magnitude less abundant than LMW diacids. Correlations of trace metals with organics, their sources, and the possible role of trace transition metals are explained.

Research and development on membrane processes for removal of acid gases during coal gasification. Final report, 20 June 1975-19 October 1976

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

Petersen, R.J.; Cadotte, J.E.; Conway, E.J.

1976-01-01

The object of this program was to develop novel and unique membranes for separating acid gases from coal gasification streams. Many candidate membranes, including cationic, hydrophilic, and silicone, were tested. Optimum separation properties were possessed by membranes formulated from crosslinked methyl cellulose coated on polysulfone support films. The observed separation properties were explained theoretically by the solubility of the various gases in the water contained within the membranes rather than by activated transport. Each of the acid gas clean-up processes considered required additional sulfur clean-up, a guard chamber, and a Claus plant for recovering sulfur. These additional costs were calculatedmore » and added to the base costs for acid gas removal from the raw SNG. When the additional costs were added to the costs of the Rectisol, Benfield, Sulfinol, and fluidized dolomite processes the total costs ranged from 43 to 49 cents/Mscf. For the membrane process the additional sulfur removal costs were about 3.3 cents/Mscf to be added to the base costs for acid gas removal. The best membrane composition found during this program, one which exhibited a CO/sub 2//H/sub 2/ selectivity of 13 at a CO/sub 2/ flux of 6 ft/sup 3//ft/sup 2/-hr-100 psi, would entail a process cost of about 53 cents/Mscf with these additions. This is about 7 cents/Mscf more than for the average of the other processes. No better membrane performance is predicted on the basis of the experiments performed. Without a shift in several cost factors, membranes cannot be competitive. The possibility that reduced energy availability could lead to such shifts should not be discounted but is not foreseen in the near future.« less

Combining stable isotope (δ13C) of trace gases and aerobiological data to monitor the entry and dispersion of microorganisms in caves.

PubMed

Garcia-Anton, E; Cuezva, S; Jurado, V; Porca, E; Miller, A Z; Fernandez-Cortes, A; Saiz-Jimenez, C; Sanchez-Moral, S

2014-01-01

Altamira Cave (north of Spain) contains one of the world's most prominent Paleolithic rock art paintings, which are threatened by a massive microbial colonization of ceiling and walls. Previous studies revealed that exchange rates between the cave and the external atmosphere through the entrance door play a decisive role in the entry and transport of microorganisms (bacteria and fungi) and nutrients to the interior of the cave. A spatial-distributed sampling and measurement of carrier (CO2) and trace (CH4) gases and isotopic signal of CO2 (δ(13)C) inside the cave supports the existence of a second connection (active gas exchange processes) with the external atmosphere at or near the Well Hall, the innermost and deepest area of the cave. A parallel aerobiological study also showed that, in addition to the entrance door, there is another connection with the external atmosphere, which favors the transport and increases microorganism concentrations in the Well Hall. This double approach provides a more complete knowledge on cave ventilation and revealed the existence of unknown passageways in the cave, a fact that should be taken into account in future cave management.

Method of removing oxides of sulfur and oxides of nitrogen from exhaust gases

DOEpatents

Walker, Richard J.

1986-01-01

A continuous method is presented for removing both oxides of sulfur and oxides of nitrogen from combustion or exhaust gases with the regeneration of the absorbent. Exhaust gas is cleaned of particulates and HCl by a water scrub prior to contact with a liquid absorbent that includes an aqueous solution of bisulfite and sulfite ions along with a metal chelate, such as, an iron or zinc aminopolycarboxylic acid. Following contact with the combustion gases the spent absorbent is subjected to electrodialysis to transfer bisulfite ions into a sulfuric acid solution while splitting water with hydroxide and hydrogen ion migration to equalize electrical charge. The electrodialysis stack includes alternate layers of anion selective and bipolar membranes. Oxides of nitrogen are removed from the liquid absorbent by air stripping at an elevated temperature and the regenerated liquid absorbent is returned to contact with exhaust gases for removal of sulfur oxides and nitrogen oxides.

Separation of polar gases from nonpolar gases

DOEpatents

Kulprathipanja, S.

1986-08-19

The separation of polar gases from nonpolar gases may be effected by passing a mixture of nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol plasticizer having a molecular weight of from about 200 to about 600 and an organic polymer cast on a porous support. The porous support is pretreated prior to casting of the mixture thereon by contact with a polyhydric alcohol whereby the pores of the support are altered, thus adding to the increased permeability of the polar gas.

Measurements of reactive trace gases and variable O 3 formation rates in some South Carolina biomass burning plumes

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

Akagi, S. K.; Yokelson, R. J.; Burling, I. R.

2013-02-01

In October-November 2011 we measured the trace gas emission factors from 7 prescribed fires in South Carolina, U.S. using two Fourier transform infrared spectrometer (FTIR) systems and whole air sampling (WAS) into canisters followed by gas-chromatographic analyses. The fires were intended to emulate high-intensity burns as they were lit during the dry season and in most cases represented stands that had not been treated with prescribed burns in 10+ years, if at all. A total of 97 trace gas species are reported here from both airborne and ground-based platforms making this one of the most detailed field studies of firemore » emissions to date. The measurements included the first data for a suite of monoterpene compounds emitted via distillation of plant tissues during real fires. The known chemistry of the monoterpenes and their measured abundance of ~0.40% of CO (molar basis), ~3.9% of NMOC (molar basis), and ~21% of organic aerosol (mass basis), suggests that they impacted post-emission formation of ozone, aerosol, and small organic trace gases such as methanol and formaldehyde in the sampled plumes. The variability in the terpene emissions in South Carolina (SC) fire plumes was high and, in general, the speciation of the emitted gas-phase non-methane organic compounds was surprisingly different from that observed in a similar study in nominally similar pine forests in North Carolina ~20 months earlier. It is likely that the slightly different ecosystems, time of year and the precursor variability all contributed to the variability in plume chemistry observed in this study and in the literature. The ΔHCN/ΔCO emission ratio, however, is fairly consistent at 0.9 ± 0.06 % for airborne fire measurements in coniferous-dominated ecosystems further confirming the value of HCN as a good biomass burning indicator/tracer. The SC results also support an earlier finding that C 3-C 4 alkynes may be of use as biomass burning indicators on the time-scale of hours to a day

Differentiation of farmed and wild turbot (Psetta maxima): proximate chemical composition, fatty acid profile, trace minerals and antimicrobial resistance of contaminant bacteria.

PubMed

Martínez, B; Miranda, J M; Nebot, C; Rodriguez, J L; Cepeda, A; Franco, C M

2010-10-01

The proximate, cholesterol, fatty acid and trace mineral compositions in the flesh of farmed and wild turbot (Psetta maxima) were evaluated. Additionally, the potential influence of the use of antimicrobial agents in the bacteria carried by farmed turbot was investigated. For this purpose, a total of 144 Pseudomonas spp. and 127 Aeromonas spp. were isolated and tested for their susceptibility to 12 antimicrobials by a disk diffusion method. Farmed turbot contained higher fat, cholesterol and calories as well as lower moisture content than its wild counterpart. The fatty acid profile of farmed turbot included higher levels of myristic, pentadecanoic, palmitoleic, gadoleic, cetoleic, linoleic, linolenic, stearidonic, eicosadienoic and eicosapentaenoic acids, and lower levels of stearic, arachidonic, docosapentaenoic and docosahexaenoic acids than its wild counterpart. The proportions of polyunsaturated fatty acids and n-3/n-6 ratios were higher in wild turbot than in farmed turbot. With respect to trace minerals, no toxic levels were found, and higher amounts of Cd, Co, Cu, Fe, Mn, Pb and Zn, as well as lower amounts of Cr, were found in farmed turbot relative to wild turbot. The antimicrobial resistance of Pseudomonas spp. and Aeromonas spp. were quite similar, with only the trimethoprim-sulfamethoxazole resistance of Aeromonas spp. isolated from farmed turbot being higher than those isolated from wild turbot. In the case of ampicillin, Pseudomonas spp. isolated from wild turbot showed higher resistance levels than those of their counterparts isolated from farmed turbot. In conclusion, the nutritional parameters of wild turbot are more adequate with respect to nutritional recommendations, while no differences were observed in food safety derived from trace mineral concentrations or the antimicrobial resistance of bacteria isolated from wild and farmed turbot.

A 10 micron laser heterodyne spectrometer for remote detection of trace gases

NASA Technical Reports Server (NTRS)

Mumma, M. J.; Kostiuk, T.; Buhl, D.

1978-01-01

Infrared heterodyne spectroscopy provides a means of measuring the intensity profiles of individual rotation-vibration spectral lines with high sensitivity. Considerable effort has been expended on optimizing these instruments for remote measurements of gases in planetary atmospheres with the result that present-generation spectrometers are beginning to provide new and startling results on the planets. The fundamental principles of laser heterodyne spectroscopy are discussed. Detailed considerations of the optical design and the electronic design of the spectral-line receiver are given. Representative results obtained with this spectrometer are discussed, including precision frequency measurements of NH3 (nu-2) lines, detection of auroral emission from Jupiter, and measurements of terrestrial O3 and CO2.

CARBON TRACE GASES IN LAKE AND BEAVER POND ICE NEAR THOMPSON, MANITOBA, CANADA

EPA Science Inventory

Concentrations of CO2, CO, and CH4 were measured in beaver pond and lake ice in April 1996 near Thompson, Manitoba to derive information on possible impacts of ice melting on corresponding atmospheric trace gas concentrations. CH4 concentrations in beaver pond and lake ice ranged...

[A trace methane gas sensor using mid-infrared quantum cascaded laser at 7.5 microm].

PubMed

Chen, Chen; Dang, Jing-Min; Huang, Jian-Qiang; Yang, Yue; Wang, Yi-Ding

2012-11-01

Presented is a compact instrument developed for in situ high-stable and sensitive continuous measurement of trace gases in air, with results shown for ambient methane (CH4) concentration accurate, real-time and in-situ. This instrument takes advantage of recent technology in thermoelectrically cooling (TEC) pulsed Fabry-Perot (FP) quantum cascaded laser (QCL) driving in a pulse mode operating at 7.5 microm ambient temperature to cover a fundamental spectral absorption band near v4 of CH4. A high quality Liquid Nitrogen (LN) cooled Mercury Cadmium Telluride (HgCdTe) mid-infrared (MIR) detector is used along with a total reflection coated gold ellipsoid mirror offering 20 cm single pass optical absorption in an open-path cell to achieve stability of 5.2 x 10(-3) under experimental condition of 200 micromol x mol(-1) measured ambient CH4. The instrument integrated software via time discriminating electronics technology to control QCL provides continuous quantitative trace gas measurements without calibration. The results show that the instrument can be applied to field measurements of gases of environmental concern. Additional, operator could substitute a QCL operating at a different wavelength to measure other gases.

Separation of polar gases from nonpolar gases

DOEpatents

Kulprathipanja, Santi; Kulkarni, Sudhir S.

1986-01-01

Polar gases such as hydrogen sulfide, sulfur dioxide and ammonia may be separated from nonpolar gases such as methane, nitrogen, hydrogen or carbon dioxide by passing a mixture of polar and nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol plasticizer having a molecular weight of from about 200 to about 600 and an organic polymer cast on a porous support. The use of such membranes as exemplified by polyethylene glycol and silicon rubber composited on polysulfone will permit greater selectivity accompanied by a high flux rate in the separation process.

Separation of polar gases from nonpolar gases

DOEpatents

Kulprathipanja, S.; Kulkarni, S.S.

1986-08-26

Polar gases such as hydrogen sulfide, sulfur dioxide and ammonia may be separated from nonpolar gases such as methane, nitrogen, hydrogen or carbon dioxide by passing a mixture of polar and nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol plasticizer having a molecular weight of from about 200 to about 600 and an organic polymer cast on a porous support. The use of such membranes as exemplified by polyethylene glycol and silicon rubber composited on polysulfone will permit greater selectivity accompanied by a high flux rate in the separation process.

COMMIT in 7-SEAS/BASELInE: Operation of and Observations from a Novel, Mobile Laboratory for Measuring In-Situ Properties of Aerosols and Gases

NASA Technical Reports Server (NTRS)

Pantina, Peter; Tsay, Si-Chee; Hsiao, Ta-Chih; Loftus, Adrian M.; Kuo, Ferret; Ou-Yang, Chang-Feng; Sayer, Andrew M.; Wang, Shen-Hsiang; Lin, Neng-Huei; Hsu, N. Christina;

Measurements of HNO3, SO2 High Resolution Aerosol SO4 (sup 2-), and Selected Aerosol Species Aboard the NASA DC-8 Aircraft: During the Transport and Chemical Evolution Over the Pacific Airborne Mission (TRACE-P)

NASA Technical Reports Server (NTRS)

Talbot, Robert W.; Dibb, Jack E.

2004-01-01

The UNH investigation during TRACE-P provided measurements of selected acidic gases and aerosol species aboard the NASA DC-8 research aircraft. Our investigation focused on measuring HNO3, SO2, and fine (less than 2 microns) aerosol SO4(sup 2-) with two minute time resolution in near-real-time. We also quantified mixing ratios of aerosol ionic species, and aerosol (210)Pb and (7)Be collected onto bulk filters at better than 10 minute resolution. This suite of measurements contributed extensively to achieving the principal objectives of TRACE-P. In the context of the full data set collected by experimental teams on the DC-8, our observations provide a solid basis for assessing decadal changes in the chemical composition and source strength of Asian continental outflow. This region of the Pacific should be impacted profoundly by Asian emissions at this time with significant degradation of air quality over the next few decades. Atmospheric measurements in the western Pacific region will provide a valuable time series to help quantify the impact of Asian anthropogenic activities. Our data also provide important insight into the chemical and physical processes transforming Asian outflow during transport over the Pacific, particularly uptake and reactions of soluble gases on aerosol particles. In addition, the TRACE-P data set provide strong constraints for assessing and improving the chemical fields simulated by chemical transport models.

Trace Gas Measurements on Mars and Earth Using Optical Parametric Generation

NASA Technical Reports Server (NTRS)

Numata, Kenji; Haris, Riris; Li, Steve; Sun, Xiaoli; Abshire, James Brice

2010-01-01

Trace gases and their isotopic ratios in planetary atmospheres offer important but subtle clues as to the origins of a planet's atmosphere, hydrology, geology, and potential for biology. An orbiting laser remote sensing instrument is capable of measuring trace gases on a global scale with unprecedented accuracy, and higher spatial resolution that can be obtained by passive instruments. We have developed an active sensing instrument for the remote measurement of trace gases in planetary atmospheres (including Earth). The technique uses widely tunable, seeded optical parametric generation (OPG) to measure methane, CO2, water vapor, and other trace gases in the near and mid-infrared spectral regions. Methane is a strong greenhouse gas on Earth and it is also a potential biogenic marker on Mars and other planets. Methane in the Earth's atmosphere survives for a shorter time than CO2 but its impact on climate change can be larger than CO2. Methane levels have remained relatively constant over the last decade around 1.78 parts per million (ppm) but recent observations indicate that methane levels may be on the rise. Increasing methane concentrations may trigger a positive feedback loop and a subsequent runaway greenhouse effect, where increasing temperatures result in increasing methane levels. The NRC Decadal Survey recognized the importance of global observations of greenhouse gases and called for simultaneous CH4, CO, and CO2 measurements but also underlined the technological limitations for these observations. For Mars, methane measurements are of great interest because of its potential as a strong biogenic marker. A remote sensing instrument that can measure day and night over all seasons and latitudes can identify and localize sources of biogenic gas plumes produced by subsurface chemistry or biology, and aid in the search for extra-terrestrial life. It can identify the dynamics of methane generation over time and latitude and identify future lander mission sites

Vapor-deposited water and nitric acid ices

NASA Astrophysics Data System (ADS)

Leu, Ming-Taun; Keyser, Leon F.

Ices formed by vapor deposition have been the subject of numerous laboratory investigations in connection with snow and glaciers on the ground, ice clouds in the terrestrial atmosphere, surfaces of other planets and their satellites, and the interstellar medium. In this review we will focus on these specific subjects: (1) heterogeneous chemistry on the surfaces of polar stratospheric clouds (PSCs) and (2) surfaces of satellites of the outer planets in our solar system. Stratospheric ozone provides a protective shield for mankind and the global biosphere from harmful ultraviolet solar radiation. In past decades, theoretical atmospheric models for the calculation of ozone balance frequently used only homogeneous gas-phase reactions in their studies. Since the discovery of the Antarctic ozone hole in 1985, however, it has been demonstrated that knowledge of heterogeneous reactions on the surface of PSCs is definitely needed to understand this significant natural event due to the anthropogenic emission of chlorofluorocarbons (CFCs). We will briefly discuss the experimental techniques for the investigation of heterogeneous chemistry on ice surfaces carried out in our laboratories. The experimental apparatus used include: several flow-tube reactors, an electron-impact ionization mass spectrometer, a Fourier transform infrared spectrometer, a BET adsorption apparatus, and a scanning environmental electron microscope. The adsorption experiments and electron microscopic work have demonstrated that the vapor-deposited ices are highly porous. Therefore, it is necessary to develop theoretical models for the elucidation of the uptake and reactivity of trace gases in porous ice substrates. Several measurements of uptake and reaction probabilities of these trace gases on water ices and nitric acid ices have been performed under ambient conditions in the upper troposphere and lower stratosphere, mainly in the temperature range 180-220 K. The trace gases of atmospheric importance

Trace Gas Quantification with Small Unmanned Aerial Systems

NASA Astrophysics Data System (ADS)

Schuyler, T. J.; Guzman, M. I.; Bailey, S.; Jacob, J.

2017-12-01

Measurements of atmospheric composition are generally performed with advanced instrumentation from ground stations using tall towers and weather balloons or with manned aircraft. Unmanned aerial systems (UAS) are a promising technology for atmospheric monitoring of trace atmospheric gases as they can bridge the gap between the regions of the atmospheric boundary layer measured by ground stations and aircraft. However, in general, the sophisticated instrumentation required for these measurements are heavy, preventing its deployment with small UAS. In order to successfully detect and quantify these gases, sensor packages aboard UAS must be lightweight, have low-power consumption, and possess limits of detection on the ppm scale or below with reasonably fast response times. Thus, a new generation of portable instrument is being developed in this work to meet these requirements employing new sensing packages. The cross sensitivity of these sensors to several gases is examined through laboratory testing of the instrument under variable environmental conditions prior to performing field measurements. Datasets include timestamps with position, temperature, relative humidity, pressure, along with variable mixing ratio values of important greenhouse gases. The work will present an analysis of the results gathered during authorized flights performed during the second CLOUD-MAP§ field campaign held in June 2017. §CLOUD-MAP: Collaboration Leading Operational UAS Development for Meteorology and Atmospheric Physics, a 4-year NSF funded effort.

Adsorptive conversion of nitrogen dioxide from etching vent gases over activated carbon.

PubMed

Fang, Mei-Ling; Wu, Ching-Yi; Chou, Ming-Shean

2018-04-13

Some metal etching operations emit limited flow rates of waste gases with reddish-brown NO 2 fume, which may cause visual and acidic-odor complaints, as well as negative health effects. In this study, tests were performed by passing caustic-treated waste gases vented from Al-etching operations through columns packed either with virgin or regenerated granular activated carbon (GAC) to test their adsorptive conversion performance of NO 2 in the gases. The gases contained 5-55 ppm NO 2 and acetic and nitric acids of below 3 ppm. Exhausted carbon was regenerated by scrubbing it with caustic solution and water, and dried for further adsorption tests. Results indicate that with an (empty bed residence time (EBRT) of 0.15 sec for the gas through the GAC-packed space, around 60% of the influent NO 2 of 54 ppm could be removed, and 47% of the removed NO 2 was converted by and desorbed from the carbon as NO. GAC used in the present study could be regenerated at least twice to restore its capacity for NO 2 adsorption. Within EBRTs of 0.076-0.18 sec, the adsorptive conversion capacity was linearly varied with EBRT. In practice, with an EBRT of 0.20 sec, a conversion capacity of 0.80 kg NO 2 (kg GAC) -1 with an influent NO 2 of 40 ppm can be used as a basis for system design. Some metal etching operations emit waste gases with reddish-brown (yellow when diluted) NO 2 fume which may cause visual and acidic-odor complaints, as well as negative health effects. This study provides a simple process for the adsorptive conversion of NO 2 in caustic-treated waste gases vented from metal-etching operations through a GAC column. With an EBRT of 0.20 sec, a conversion capacity of 0.80 kg NO 2 (kg GAC) -1 with an influent NO 2 of 40 ppm can be used as a basis for system design. Saturated GAC can be regenerated at least twice by simply scrubbing it with aqueous caustic solution.

Rare gases systematics and mantle structure

NASA Technical Reports Server (NTRS)

Allegre, C. J.; Staudacher, T.

1994-01-01

The following points are emphasized: one of the most important ones is certainly the first set of experimental data on the solubility of noble gases in metal phases at intermediate pressures, since the core was certainly not formed at ultra high pressures, as emphasized by Ahrens and confirmed by trace elements systematics Wanke. The experimental data clearly show that the core can not be a major reservoir for terrestrial rare gases; the second point is a more elaborate reconsideration of the (40)K-(40)Ar budget of the Earth. This shows that (40)Ar contained in continental crust plus upper mantle plus atmosphere is at maximum half of the (40)Ar inventory of the whole earth. This implies the existence of a two layered mantle; the third point is the discovery by the Australian noble gases group of the existence of high (20)Ne/(22)Ne and low (21)Ne/(22)Ne isotopic ratios in Loihi seamount samples. This results which are different to the MORB ratios confirm the idea of a two layered model, but suggest the existence of a primordial solar type Ne reservoir. Several possibilities about the origin of this (20)Ne excess in the mantle will be discussed; The high (40)Ar/(36)Ar, (129)Xe/(130)Xe and (134) Xe/(130)Xe, (136)Xe/(130)Xe are confirmed by new data. The corresponding ratios for the lower mantle will be discussed. (40)Ar/(36)Ar ratios up to 6000 can be accepted and will not modify the general model of the mantle. They confirm the atmosphere chronology, about 85 percent of the atmosphere was formed in the first 50 My and 15 percent later on.

Observations of halogenated trace gases in Taiwan and Malaysia

NASA Astrophysics Data System (ADS)

Gooch, Lauren J.; Laube, Johannes C.; Sturges, William T.; Oram, David E.; Wang, Jia-Lin; Ou-Yang, Cheng-Feng; Lin, Neng-Huei; Mead, Iq; Rigby, Matt; White, Emily

2015-04-01

There are a large variety of halocarbons present in the atmosphere that significantly impact on stratospheric ozone depletion and/or global warming. Though the use of some of these compounds has been phased out and replaced under global control measures, relatively long atmospheric lifetimes, imperfect substitutes and incomplete reductions in usage mean that global concentrations of halocarbons still require regular monitoring. This is especially true for the rapidly developing East Asian region, where high emissions have been repeatedly reported in recent years. We here present results from an air sampling activity in Taiwan and Malaysia during the spring months of 2013 and 2014. A large range of halocarbons, including a number of novel gases, were investigated via high sensitivity gas chromatography mass spectrometry (GC-MS). We find periods of relatively clean air as well as episodes that appear to be impacted by urban and/or industrial emissions and examine correlations between individual species. Observed mixing ratios are compared in context with both global background data and other regional studies. Enhancements in the abundances of many halocarbons are detected with examples including the Halons 1211 and 1202 as well as the very long-lived perfluorocarbons c-C4F8, C5F12 and C7F16. We also show and evaluate unusually high mixing ratios of other globally growing halocarbons such as sulphur hexafluoride (SF6), HCFC-133a (CF3CH2Cl), and CFC-113a (CF3CCl3). Finally, we use NAME analysis to produce back-trajectories in order to assess possible regional emission sources.

Apparatus for the plasma destruction of hazardous gases

DOEpatents

Kang, M.

1995-02-07

A plasma cell for destroying hazardous gases is described. An electric-discharge cell having an electrically conducting electrode onto which an alternating high-voltage waveform is impressed and a dielectric barrier adjacent thereto, together forming a high-voltage electrode, generates self-terminating discharges throughout a volume formed between this electrode and a grounded conducting liquid electrode. The gas to be transformed is passed through this volume. The liquid may be flowed, generating thereby a renewable surface. Moreover, since hydrochloric and hydrofluoric acids may be formed from destruction of various chlorofluorocarbons in the presence of water, a conducting liquid may be selected which will neutralize these corrosive compounds. The gases exiting the discharge region may be further scrubbed if additional purification is required. 4 figs.

Apparatus for the plasma destruction of hazardous gases

DOEpatents

Kang, Michael

1995-01-01

A plasma cell for destroying hazardous gases. An electric-discharge cell having an electrically conducting electrode onto which an alternating high-voltage waveform is impressed and a dielectric barrier adjacent thereto, together forming a high-voltage electrode, generates self-terminating discharges throughout a volume formed between this electrode and a grounded conducting liquid electrode. The gas to be transformed is passed through this volume. The liquid may be flowed, generating thereby a renewable surface. Moreover, since hydrochloric and hydrofluoric acids may be formed from destruction of various chlorofluorocarbons in the presence of water, a conducting liquid may be selected which will neutralize these corrosive compounds. The gases exiting the discharge region may be further scrubbed if additional purification is required.

Carbon and hydrogen isotopic evidence for the origin of combustible gases in water-supply wells in north-central Pennsylvania

USGS Publications Warehouse

Révész, K. M.; Breen, K.J.; Baldassare, A.J.; Burruss, R.C.

2010-01-01

The origin of the combustible gases in groundwater from glacial-outwash and fractured-bedrock aquifers was investigated in northern Tioga County, Pennsylvania. Thermogenic methane (CH4) and ethane (C2H6) and microbial CH4 were found. Microbial CH4 is from natural in situ processes in the shale bedrock and occurs chiefly in the bedrock aquifer. The δ13C values of CH4 and C2H6 for the majority of thermogenic gases from water wells either matched or were between values for the samples of non-native storage-field gas from injection wells and the samples of gas from storage-field observation wells. Traces of C2H6 with microbial CH4 and a range of C and H isotopic compositions of CH4 indicate gases of different origins are mixing in sub-surface pathways; gas mixtures are present in groundwater. Pathways for gas migration and a specific source of the gases were not identified. Processes responsible for the presence of microbial gases in groundwater could be elucidated with further geochemical study.

Airborne observations of greenhouse gases in the North Slope of Alaska during summer 2015

NASA Astrophysics Data System (ADS)

Biraud, S.; Torn, M. S.; Sweeney, C.; Springston, S. R.; Sedlacek, A. J., III

2015-12-01

Atmospheric temperatures are warming faster in the Arctic than predicted by climate models. The impact of this warming on permafrost degradation is not well understood, but it is projected to increase carbon decomposition and greenhouse gas production (CO2 and/or CH4) by arctic ecosystems. Airborne observations of atmospheric trace gases, aerosols and cloud properties in North Slopes of Alaska (NSA) are improving our understanding of global climate, with the goal of reducing the uncertainty in global and regional climate simulations and projections. From June 1 through September 15, 2015, the Atmospheric radiation measurement (ARM) airborne facility (AAF) deployed a G1 research aircraft (ARM-ACME-V mission) to fly over the North Slope of Alaska, with occasional vertical profiling to measure trace gas concentrations, between Prudhoe Bay, Oliktok point, Barrow, Atqasuk, Ivotuk, and Toolik Lake. The aircraft payload includes a Picarro and a LGR analyzers for continuous measurements of CO2, CH4, H2O, and CO and N2O mixing ratios, and a 12-flask sampler for analysis of carbon cycle gases (CO2, CO, CH4, N2O, 13CO2, 14CO2, carbonyl sulfide, and trace hydrocarbon species including ethane). The aircraft payload also include measurements of aerosol properties (number size distribution, total number concentration, absorption, and scattering), cloud properties (droplet and ice size information), atmospheric thermodynamic state, and solar/infrared radiation. Preliminary results using CO2, CH4, CO, ethane, and soot spectroscopy observations are used to tease apart biogenic and thermogenic (biomass burning, and oil and gas production) contributions

Vertical profiling of aerosol particles and trace gases over the central Arctic Ocean during summer

NASA Astrophysics Data System (ADS)

Kupiszewski, P.; Leck, C.; Tjernström, M.; Sjogren, S.; Sedlar, J.; Graus, M.; Müller, M.; Brooks, B.; Swietlicki, E.; Norris, S.; Hansel, A.

2013-04-01

Unique measurements of vertical size resolved aerosol particle concentrations, trace gas concentrations and meteorological data were obtained during the Arctic Summer Cloud Ocean Study (ASCOS, http://www.ascos.se), an International Polar Year project aimed at establishing the processes responsible for formation and evolution of low-level clouds over the high Arctic summer pack ice. The experiment was conducted from onboard the Swedish icebreaker Oden, and provided both ship- and helicopter-based measurements. This study focuses on the vertical helicopter profiles and onboard measurements obtained during a three-week period when Oden was anchored to a drifting ice floe, and sheds light on the characteristics of Arctic aerosol particles and their distribution throughout the lower atmosphere. Distinct differences in aerosol particle characteristics within defined atmospheric layers are identified. Near the surface (lowermost couple hundred meters), transport from the marginal ice zone (MIZ), if sufficiently short (less than ca. 2 days), condensational growth and cloud-processing develop the aerosol population. During two of the four representative periods defined in this study, such influence is shown. At altitudes above about 1 km, long-range transport occurs frequently. However, only infrequently does large-scale subsidence descend such air masses to become entrained into the mixed layer in the high Arctic, and therefore they are unlikely to directly influence low-level stratiform cloud formation. Nonetheless, long-range transport plumes can influence the radiative balance of the PBL by influencing formation and evolution of higher clouds, as well as through precipitation transport of particles downwards. New particle formation was occasionally observed, particularly in the near-surface layer. We hypothesize that the origin of these ultrafine particles can be from biological processes, both primary and secondary

Vertical profiling of aerosol particles and trace gases over the central Arctic Ocean during summer

NASA Astrophysics Data System (ADS)

Kupiszewski, P.; Leck, C.; Tjernström, M.; Sjogren, S.; Sedlar, J.; Graus, M.; Müller, M.; Brooks, B.; Swietlicki, E.; Norris, S.; Hansel, A.

2013-12-01

Unique measurements of vertical size-resolved aerosol particle concentrations, trace gas concentrations and meteorological data were obtained during the Arctic Summer Cloud Ocean Study (ASCOS, www.ascos.se), an International Polar Year project aimed at establishing the processes responsible for formation and evolution of low-level clouds over the high Arctic summer pack ice. The experiment was conducted from on board the Swedish icebreaker Oden, and provided both ship- and helicopter-based measurements. This study focuses on the vertical helicopter profiles and onboard measurements obtained during a three-week period when Oden was anchored to a drifting ice floe, and sheds light on the characteristics of Arctic aerosol particles and their distribution throughout the lower atmosphere. Distinct differences in aerosol particle characteristics within defined atmospheric layers are identified. Within the lowermost couple hundred metres, transport from the marginal ice zone (MIZ), condensational growth and cloud processing develop the aerosol population. During two of the four representative periods defined in this study, such influence is shown. At altitudes above about 1 km, long-range transport occurs frequently. However, only infrequently does large-scale subsidence descend such air masses to become entrained into the mixed layer in the high Arctic, and therefore long-range transport plumes are unlikely to directly influence low-level stratiform cloud formation. Nonetheless, such plumes can influence the radiative balance of the planetary boundary layer (PBL) by influencing formation and evolution of higher clouds, as well as through precipitation transport of particles downwards. New particle formation was occasionally observed, particularly in the near-surface layer. We hypothesize that the origin of these ultrafine particles could be in biological processes, both primary and secondary, within the open leads between

Assessment of the effects of glutamic acid decarboxylase antibodies and trace elements on cognitive performance in older adults.

PubMed

Alghadir, Ahmad H; Gabr, Sami A; Al-Eisa, Einas S

2015-01-01

Homeostatic imbalance of trace elements such as iron (Fe), copper (Cu), and zinc (Zn) demonstrated adverse effects on brain function among older adults. The present study aimed to investigate the effects of trace elements and the presence of anti-glutamic acid decarboxylase antibodies (GADAs) in human cognitive abilities among healthy older adults. A total of 100 healthy subjects (65 males, 35 females; age range; 64-96 years) were recruited for this study. Based on Loewenstein Occupational Therapy Cognitive Assessment (LOTCA) score, the participants were classified according to cognitive performance into normal (n=45), moderate (n=30), and severe (n=25). Cognitive functioning, leisure-time physical activity (LTPA), serum trace elements - Fe, Cu, Zn, Zn/Cu, and GADAs were assessed using LOTCA battery, pre-validated physical activity (PA) questionnaire, atomic absorption, and immunoassay techniques, respectively. Approximately 45% of the study population (n=45) had normal distribution of cognitive function and 55% of the study population (n=55) had abnormal cognitive function; they were classified into moderate (score 62-92) and severe (score 31-62). There was a significant reduction in the level of Zn and Zn/Cu ratio along with an increase in the level of Fe, Cu, and anti-GADAs in subjects of severe (P=0.01) and moderate (P=0.01) cognitive performance. LOTCA-cognitive scores correlated positively with sex, HbA(1c), Fe, Cu, Zn, and Zn/Cu ratio, and negatively with age, PA, body mass index, and anti-GADAs. Significant inter-correlation was reported between serum trace element concentrations and anti-GADAs which suggest producing a cognitive decline via oxidative and neural damage mechanism. This study found significant associations among trace elements, anti-GADAs, and cognitive function in older adults. The homeostatic balance of trace elements should be recommended among older adults for better cognitive performance.

Temperature Programmed Desorption of Quench-condensed Krypton and Acetone in Air; Selective Concentration of Ultra-trace Gas Components.

PubMed

Suzuki, Taku T; Sakaguchi, Isao

2016-01-01

Selective concentration of ultra-trace components in air-like gases has an important application in analyzing volatile organic compounds in the gas. In the present study, we examined quench-condensation of the sample gas on a ZnO substrate below 50 K followed by temperature programmed desorption (TPD) (low temperature TPD) as a selective gas concentration technique. We studied two specific gases in the normal air; krypton as an inert gas and acetone as a reactive gas. We evaluated the relationship between the operating condition of low temperature TPD and the lowest detection limit. In the case of krypton, we observed the selective concentration by exposing at 6 K followed by thermal desorption at about 60 K. On the other hand, no selectivity appeared for acetone although trace acetone was successfully concentrated. This is likely due to the solvent effect by a major component in the air, which is suggested to be water. We suggest that pre-condensation to remove the water component may improve the selectivity in the trace acetone analysis by low temperature TPD.

[Gases in vitreoretinal surgery].

PubMed

Janco, L; Vida, R; Bartos, M; Villémová, K; Izák, M

2012-02-01

To evaluate the importance and benefits of using gases in vitreoretinal surgery. The gases represent a wide group of substances used in eye surgery for more than 100 years. The role of intraocular gases in vitreoretinal surgery is irreplaceable. Their use is still considered to be the "gold standard". An important step in eye surgery was the introduction of expanding gases--sulfur hexafluoride and perfluorocarbons into routine clinical practice. The most common indications for the use of intraocular gases are: retinal detachment, idiopathic macular hole, complications of vitreoretinal surgery and others. The introduction of intraocular gases into routine clinical practice, along with other modern surgical techniques resulted in significant improvement of postoperative outcomes in a wide range of eye diseases. Understanding the principles of intraocular gases use brings the benefits to the patient and physician as well. Due to their physical and chemical properties they pose far the best and most appropriate variant of intraocular tamponade. Gases also bring some disadvantages, such as difficulties in detailed fundus examination, visual acuity testing, ultrasonographic examination, difficulties in application of intravitreal drugs or reduced possibility of retina laser treatment. The gases significantly change optical system properties of the eye. The use of gases in vitreoretinal surgery has significantly increased success rate of retinal detachment surgery, complicated posterior segment cases, trauma, surgery of the macula and other diseases.

Trace element degassing patterns and volcanic fluxes to the atmosphere during the 2014 Holuhraun eruption, Iceland

NASA Astrophysics Data System (ADS)

Gauthier, Pierre-Jean; Sigmarsson, Olgeir; Moune, Séverine; Haddadi, Baptiste; Gouhier, Mathieu

2015-04-01

Trace elements are well known to be volatile at magma temperature and enriched in volcanic gases from active volcanoes worldwide. However, little is known so far regarding their volatility at Icelandic volcanoes, mostly because high temperature volcanic gases are often inaccessible. The 2014 Holuhraun eruption that began on August 29 is characterized by both high extrusion rates of lava and intensive degassing which gives rise to a volcanic plume made of volcanic gases, aerosols and fine solid particles. A unique opportunity to sample the diluted plume at the eruption site was given to us on October 2. Volcanic aerosols were collected on washed PTFE membranes by pumping through the diluted plume for 30 minutes to 1 hour. Reactive gases were simultaneously trapped on impregnated filters, yielding a SO2/HCl molar ratio at the eruption site of 29-46 and SO2 concentrations in the diluted plume up to 200 mg/m3 (Haddadi et al., EGU 2015). PTFE filters were leached in 5 ml of a diluted HNO3-HF mixture for one week at 90°C. Solutions were subsequently analyzed by ICP-MS using a synthetic reference solution at 10 ppb for external calibration. Both siderophile (Mo, W, Re) and calchophile trace metals (Cu, Zn, As, Se, Cd, In, Sn, Sb, Te, Tl, Pb, Bi) were found to be significantly enriched in the diluted volcanic plume of Holuhraun compared to the background atmosphere in Iceland. Measured concentrations range from less than 0.1 ng/m3 for W up to 400 ng/m3 of Cd. Enrichment factors (EF) relative to Mg, considered as a strictly lithophile element with extremely low volatility, were computed for all analyzed trace metals. The least volatile elements (W, Cu, Zn, Mo, Ag) have EFs in the range 50-300 while the most volatile elements (Cd, Bi, Re, Se, Te) have EFs as high as 10E6. The overall degassing pattern observed at Holuhraun is consistent with those previously reported for other mantle plume related volcanoes like Kilauea (Mather et al., Geochim. Cosmochim. Acta, 2012) and

Balloon-borne measurements of middle atmosphere aerosols and trace gases in Antarctica

NASA Technical Reports Server (NTRS)

Hofmann, D. J.

1988-01-01

This paper reviews data on in situ balloon-borne measurements on stratospheric ozone concentrations and aerosol contents obtained prior to 1986, along with the measurements obtained in 1986 during the National Ozone Expedition. The data indicate that the phenomenon of ozone depletion appears to be shaped spatially and temporally by dynamical stratospheric phenomena. In terms of Antarctic stratospheric research, it appears that the most important problems at the moment involve delineating the springtime ozone depletion through accurate in situ measurements of temperature, trace gas, and particle size (in addition to remote sensing from space).

Trace gas transport out of the Indian Summer Monsoon

NASA Astrophysics Data System (ADS)

Tomsche, Laura; Pozzer, Andrea; Zimmermann, Peter; Parchatka, Uwe; Fischer, Horst

2016-04-01

The trace gas transport out of the Indian summer monsoon was investigated during the aircraft campaign OMO (Oxidation Mechanism Observations) with the German research aircraft HALO (High Altitude and Long Range Research Aircraft) in July/August 2015. HALO was based at Paphos/Cyprus and also on Gan/Maledives. Flights took place over the Mediterranean Sea, the Arabian Peninsula and the Arabian Sea. In this work the focus is on the distribution of carbon monoxide (CO) and methane (CH4) in the upper troposphere. They were measured with the laser absorption spectrometer TRISTAR on board of HALO. During the Indian summer monsoon strong convection takes place over India and the Bay of Bengal. In this area the population is high accompanied by many emission sources e.g. wetlands and cultivation of rice. Consequently the boundary layer is polluted containing high concentrations of trace gases like methane and carbon monoxide. Due to vertical transport these polluted air masses are lifted to the upper troposphere. Here they circulate with the so called Asian monsoon anticyclone. In the upper troposphere polluted air masses lead to a change in the chemical composition thus influence the chemical processes. Furthermore the anticyclone spreads the polluted air masses over a larger area. Thus the outflow of the anticyclone in the upper troposphere leads to higher concentrations of trace gases over the Arabian Sea, the Arabian Peninsula and also over the eastern part of North Africa and the eastern part of the Mediterranean Sea. During OMO higher concentrations of methane and carbon monoxide were detected at altitudes between 11km and 15km. The highest measured concentrations of carbon monoxide and methane were observed over Oman. The CO concentration in the outflow of the monsoon exceeds background levels by 10-15ppb. However the enhancement in the concentration is not obviously connected to the monsoon due to the natural variability in the troposphere. The enhancement in the

Classroom Determination of Trace Organic Substances by Catalytic Methods.

ERIC Educational Resources Information Center

Wenck, Helmut; And Others

1988-01-01

Describes three trace determinations of organic substances utilizing a spectrophotometer. Provides procedures and absorbance wavelengths for determining acetonitrile, oxalic acid, and oxalic acid in human serum. Explores the role of acetonitrile and oxalic acid as catalysts in their respective reactions. (ML)

Shallow borehole array for measuring fluxes of reduced trace gases in Greenland as an analogue for volatile emission on Mars

NASA Astrophysics Data System (ADS)

Pratt, L. M.

2011-12-01

-packer-optic-capillary system as a technology demonstration of semi-autonomous drilling for planetary exploration. Carbon and hydrogen isotopic compositions for methane and ethane will be determined in the field using Integrated Cavity Output Spectroscopy and Cavity Ring Down Spectroscopy. Continuous permafrost is present at the study site down to 300 m depth with temperatures dropping to -3 degrees C at a depth of about 4 meters, providing a relatively shallow and pristine setting for an instrumented study of reduced trace gases in soil, fractured bedrock, and groundwater constituting the active layer.

Effects of land use on surface–atmosphere exchanges of trace gases and energy in Borneo: comparing fluxes over oil palm plantations and a rainforest

PubMed Central

Fowler, David; Nemitz, Eiko; Misztal, Pawel; Di Marco, Chiara; Skiba, Ute; Ryder, James; Helfter, Carole; Cape, J. Neil; Owen, Sue; Dorsey, James; Gallagher, Martin W.; Coyle, Mhairi; Phillips, Gavin; Davison, Brian; Langford, Ben; MacKenzie, Rob; Muller, Jennifer; Siong, Jambery; Dari-Salisburgo, Cesare; Di Carlo, Piero; Aruffo, Eleonora; Giammaria, Franco; Pyle, John A.; Hewitt, C. Nicholas

2011-01-01

This paper reports measurements of land–atmosphere fluxes of sensible and latent heat, momentum, CO2, volatile organic compounds (VOCs), NO, NO2, N2O and O3 over a 30 m high rainforest canopy and a 12 m high oil palm plantation in the same region of Sabah in Borneo between April and July 2008. The daytime maximum CO2 flux to the two canopies differs by approximately a factor of 2, 1200 mg C m−2 h−1 for the oil palm and 700 mg C m−2 h−1 for the rainforest, with the oil palm plantation showing a substantially greater quantum efficiency. Total VOC emissions are also larger over the oil palm than over the rainforest by a factor of 3. Emissions of isoprene from the oil palm canopy represented 80 per cent of the VOC emissions and exceeded those over the rainforest in similar light and temperature conditions by on average a factor of 5. Substantial emissions of estragole (1-allyl-4-methoxybenzene) from the oil palm plantation were detected and no trace of this VOC was detected in or above the rainforest. Deposition velocities for O3 to the rainforest were a factor of 2 larger than over oil palm. Emissions of nitrous oxide were larger from the soils of the oil palm plantation than from the soils of the rainforest by approximately 25 per cent. It is clear from the measurements that the large change in the species composition generated by replacing rainforest with oil palm leads to profound changes in the net exchange of most of the trace gases measured, and thus on the chemical composition of the boundary layer over these surfaces. PMID:22006962

Effects of land use on surface-atmosphere exchanges of trace gases and energy in Borneo: comparing fluxes over oil palm plantations and a rainforest.

PubMed

Fowler, David; Nemitz, Eiko; Misztal, Pawel; Di Marco, Chiara; Skiba, Ute; Ryder, James; Helfter, Carole; Cape, J Neil; Owen, Sue; Dorsey, James; Gallagher, Martin W; Coyle, Mhairi; Phillips, Gavin; Davison, Brian; Langford, Ben; MacKenzie, Rob; Muller, Jennifer; Siong, Jambery; Dari-Salisburgo, Cesare; Di Carlo, Piero; Aruffo, Eleonora; Giammaria, Franco; Pyle, John A; Hewitt, C Nicholas

2011-11-27

This paper reports measurements of land-atmosphere fluxes of sensible and latent heat, momentum, CO(2), volatile organic compounds (VOCs), NO, NO(2), N(2)O and O(3) over a 30 m high rainforest canopy and a 12 m high oil palm plantation in the same region of Sabah in Borneo between April and July 2008. The daytime maximum CO(2) flux to the two canopies differs by approximately a factor of 2, 1200 mg C m(-2) h(-1) for the oil palm and 700 mg C m(-2) h(-1) for the rainforest, with the oil palm plantation showing a substantially greater quantum efficiency. Total VOC emissions are also larger over the oil palm than over the rainforest by a factor of 3. Emissions of isoprene from the oil palm canopy represented 80 per cent of the VOC emissions and exceeded those over the rainforest in similar light and temperature conditions by on average a factor of 5. Substantial emissions of estragole (1-allyl-4-methoxybenzene) from the oil palm plantation were detected and no trace of this VOC was detected in or above the rainforest. Deposition velocities for O(3) to the rainforest were a factor of 2 larger than over oil palm. Emissions of nitrous oxide were larger from the soils of the oil palm plantation than from the soils of the rainforest by approximately 25 per cent. It is clear from the measurements that the large change in the species composition generated by replacing rainforest with oil palm leads to profound changes in the net exchange of most of the trace gases measured, and thus on the chemical composition of the boundary layer over these surfaces.

Laser-based sensor for detection of hazardous gases in the air using waveguide CO2 laser.

PubMed

Gondal, Mohammed A; Bakhtiari, Imran A; Dastageer, Abdul K

2007-06-01

A spectrometer based on the principle of photoacoustic spectroscopy has been developed recently at our laboratory for the detection of hazardous gases such as O3, C2H4, SO2, NO2 and SF6. In most of our earlier works, we employed a mechanical chopper to modulate the laser beam and this chopper modulation has the crucial disadvantage of instability in the chopper frequency. Even a minor shift of about 1 Hz in the modulation frequency could significantly reduce the photoacoustic signal by an order of magnitude at the acoustic resonant mode of the photoacoustic cell. To overcome this problem, we developed a photoacoustic spectrometer where a wave guided CW CO2 laser beam is modulated electronically with the external frequency generator. Our preliminary results show that the electronic modulation of CO2 laser beam improved the sensitivity of our spectrometer by a factor of 6. The parametric dependence of photoacoustic signal on laser power, modulation frequency and trace gas concentration, was investigated and the comparison between the two modulation techniques is presented in this paper for detection of trace gases such as C2H4.

Volcano-Hydrothermal Systems of the Kuril Island Arc (Russia): Geochemistry of the Thermal Waters and Gases.

NASA Astrophysics Data System (ADS)

Kalacheva, E.; Taran, Y.; Voloshina, E.; Kotenko, T.; Tarasov, K.

2017-12-01

More than 30 active volcanoes with historical eruptions are known on 20 main islands composing the Kuril Arc. Eight islands - Paramushir, Shiashkotan, Rasshua, Ushishir, Ketoy, Urup, Iturup and Kunashir - are characterized by hydrothermal activity, complementary to the fumarole activity in the craters and volcano slopes. At Paramushir, Shiashkotan, Iturup and Kunashir most of thermal manifestations are acidic to ultra-acidic hot springs associated with hydrothermal aquifers inside volcano edifices. The most powerful of them is the ultra-acid hydrothermal system of Ebeko volcano (Paramushir island) with more than 80 t/day of the chloride output and pH of springs of 1.5. At the summit part of the Ebeko volcano there are 12 thermal fields with the total thermal area exceeding 1 km2. The measured temperatures of fumaroles are from 98º C to 500ºC. Another type of hydrothermal activity are the wide spread coastal hot and neutral springs situated as a rule within the tide zone. Four groups of this type of thermal manifestation were found on the western shore of Shiashkotan island. It have Na-Ca-Cl-SO4 composition with temperatures 50-80°C and TDS 7-8 g/L. Coastal neutral springs were found also on Russhua, Uturup and Kunashir islands. Ushishir volcano-hydrothermal system in the middle of the arc is formed by the absorption of magmatic gases by seawater. In the crater of the Pallas cone (Ketoy island) there is a small Glazok lake with acid SO4 water and pH=2.4, TDS=2g/L, T=12oC. Ketoy volcano on the same island hosts a high temperature hydrothermal system with unusual boiling Ca-Na-SO4 neutral springs and steam vents. Mendeleev and Golovnin volcanoes on Kunashir Island are the southernmost of the Kuril arc. Mendeleev edifice is a centre of a large thermal area with many manifestations of different types including steam vents, acid springs and neutral coastal springs. In a 4.2x4 km wide caldera of Golovnin volcano there are two lakes with acid Cl-SO4 water and numerous

Trace element status and fatty acids metabolism during healthy ageing: an example of a population from the Tunisian eastern coast.

PubMed

Sfar, Sonia; El Heni, Jihen; Laporte, François; Braham, Hamadi; Jawed, Abdelhafidh; Amor, Salah; Sfar, Mohamed Tahar; Kerkeni, Abdelhamid

2012-03-01

Micronutrients as well as essential fatty acids are indispensable for the correct functioning of the organism. The risk of disturbance in the associated nutrition and metabolism is expected to increase during ageing. In addition, it seems that trace elements are involved in the fatty acids metabolism. The aim of the present study was then to assess age-related changes in trace elements status and in plasma essential fatty acids composition with an emphasis on the desaturase activity estimation. Two hundred healthy Tunisian subjects (30-85 years old) were recruited and separated into two subgroups: elderly (65-85 years old) and middle-aged (30-60 years old). The findings revealed that plasma zinc and calcium concentrations significantly decreased according to age. The prevalence of zinc deficiency was therefore shown to increase in old age (over 60% of elderly subjects were deficient or at risk of deficiency). No age-related changes were obtained for copper or magnesium status. The Δ6 desaturase, involved in the EFAs conversion, was shown to decrease according to age and to be associated with the plasma zinc level. Since elderly subjects were at risk of nutritional imbalance, it would be interesting to set optimal dietary proportion. This will help to prevent age-associated alterations and diseases for a better and healthy ageing. Copyright © 2011 Elsevier Inc. All rights reserved.

Trace gas and particle emissions from open biomass burning in Mexico

Treesearch

R. J. Yokelson; I. R. Burling; Shawn Urbanski; E. L. Atlas; K. Adachi; P. R. Buseck; C. Wiedinmyer; S. K. Akagi; D. W. Toohey; C. E. Wold

2011-01-01

We report airborne measurements of emission factors (EF) for trace gases and PM2.5 made in southern Mexico in March of 2006 on 6 crop residue fires, 3 tropical dry forest fires, 8 savanna fires, 1 garbage fire, and 7 mountain pine-oak forest fires. The savanna fire EF were measured early in the local dry season and when compared to EF measured late in the African dry...

Flow immune photoacoustic sensor for real-time and fast sampling of trace gases

NASA Astrophysics Data System (ADS)

Petersen, Jan C.; Balslev-Harder, David; Pelevic, Nikola; Brusch, Anders; Persijn, Stefan; Lassen, Mikael

2018-02-01

A photoacoustic (PA) sensor for fast and real-time gas sensing is demonstrated. The PA cell has been designed for flow noise immunity using computational fluid dynamics (CFD) analysis. PA measurements were conducted at different flow rates by exciting molecular C-H stretch vibrational bands of hexane (C6H14) in clean air at 2950cm-1 (3.38 μm) with a custom made mid-infrared interband cascade laser (ICL). The PA sensor will contribute to solve a major problem in a number of industries using compressed air by the detection of oil contaminants in high purity compressed air. We observe a (1σ, standard deviation) sensitivity of 0.4 +/-0.1 ppb (nmol/mol) for hexane in clean air at flow rates up to 2 L/min, corresponding to a normalized noise equivalent absorption (NNEA) coefficient of 2.5×10-9 W cm-1 Hz1/2, thus demonstrating high sensitivity and fast and real-time gas analysis. The PA sensor is not limited to molecules with C-H stretching modes, but can be tailored to measure any trace gas by simply changing the excitation wavelength (i.e. the laser source) making it useful for many different applications where fast and sensitive trace gas measurements are needed.

Two Catalysts for Selective Oxidation of Contaminant Gases

NASA Technical Reports Server (NTRS)

Wright, John D.

2011-01-01

Two catalysts for the selective oxidation of trace amounts of contaminant gases in air have been developed for use aboard the International Space Station. These catalysts might also be useful for reducing concentrations of fumes in terrestrial industrial facilities especially facilities that use halocarbons as solvents, refrigerant liquids, and foaming agents, as well as facilities that generate or utilize ammonia. The first catalyst is of the supported-precious-metal type. This catalyst is highly active for the oxidation of halocarbons, hydrocarbons, and oxygenates at low concentrations in air. This catalyst is more active for the oxidation of hydrocarbons and halocarbons than are competing catalysts developed in recent years. This catalyst completely converts these airborne contaminant gases to carbon dioxide, water, and mineral acids that can be easily removed from the air, and does not make any chlorine gas in the process. The catalyst is thermally stable and is not poisoned by chlorine or fluorine atoms produced on its surface during the destruction of a halocarbon. In addition, the catalyst can selectively oxidize ammonia to nitrogen at a temperature between 200 and 260 C, without making nitrogen oxides, which are toxic. The temperature of 260 C is higher than the operational temperature of any other precious-metal catalyst that can selectively oxidize ammonia. The purpose of the platinum in this catalyst is to oxidize hydrocarbons and to ensure that the oxidation of halocarbons goes to completion. However, the platinum exhibits little or no activity for initiating the destruction of halocarbons. Instead, the attack on the halocarbons is initiated by the support. The support also provides a high surface area for exposure of the platinum. Moreover, the support resists deactivation or destruction by halogens released during the destruction of halocarbons. The second catalyst is of the supported- metal-oxide type. This catalyst can selectively oxidize ammonia to

High temperature abatement of acid gases from waste incineration. Part II: Comparative life cycle assessment study.

PubMed

Biganzoli, Laura; Racanella, Gaia; Marras, Roberto; Rigamonti, Lucia

2015-01-01

The performances of a new dolomitic sorbent, named Depurcal®MG, to be directly injected at high temperature in the combustion chamber of Waste-To-Energy (WTE) plants as a preliminary stage of deacidification, were experimentally tested during full-scale commercial operation. Results of the experimentations were promising, and have been extensively described in Biganzoli et al. (2014). This paper reports the Life Cycle Assessment (LCA) study performed to compare the traditional operation of the plants, based on the sole sodium bicarbonate feeding at low temperature, with the new one, where the dolomitic sorbent is injected at high temperature. In the latter the sodium bicarbonate is still used, but at lower rate because of the decreased load of acid gases entering the flue gas treatment line. The major goal of the LCA was to make sure that a burden shifting was not taking place somewhere in the life cycle stages, as it might be the case when a new material is used in substitution of another one. According to the comparative approach, only the processes which differ between the two operational modes were included in the system boundaries. They are the production of the two reactants and the treatment of the corresponding solid residues arising from the neutralisation of acid gases. The additional CO2 emission at the stack of the WTE plant due to the activation of the sodium bicarbonate was also included in the calculation. Data used in the modelling of the foreground system are primary, derived from the experimental tests described in Biganzoli et al. (2014) and from the dolomitic sorbent production plant. The results of the LCA show minor changes in the potential impacts between the two operational modes of the plants. These differences are for 8 impact categories in favour of the new operational mode based on the addition of the dolomitic sorbent, and for 7 impact categories in favour of the traditional operation. A final evaluation was conducted on the potential

Trace gases and air mass origin at Kaashidhoo, Indian Ocean

NASA Astrophysics Data System (ADS)

Lobert, Jürgen M.; Harris, Joyce M.

2002-10-01

Carbon monoxide (CO) was measured at the Kaashidhoo Climate Observatory (KCO, Republic of Maldives) between February 1998 and March 2000 to assess the regional pollution of the remote atmosphere in the northern Indian Ocean. CO showed a distinct annual cycle with maximum daily mixing ratios of around 240 parts per billion (ppb), a seasonal difference of about 200 ppb, and high variability during the dry seasons. Detailed air mass trajectory analysis for 1998, 1999, and 2000 was used to identify source regions and to associate them with various levels of pollution encountered at KCO. We conclude that most significant changes in local pollution throughout the year are caused by changes in air masses. Air at KCO generally originated from three main regions with decreasing pollution: India and southeast Asia, the Arabian Sea, and the Southern Hemisphere. We show that isentropic air mass trajectories can be used to predict CO pollution levels at KCO to a certain extent and vice versa. Nitrous oxide, CFC-11, CFC-12, CCI4, and SF6 were measured during the Indian Ocean Experiment (February to March 1999) to support pollution analysis and to confirm that India is the main source for heavy pollution measured at KCO. Correlations between CO and other gases and aerosol properties measured at the surface illustrate that CO may also be used as a proxy for aerosol loading and general pollution at the surface.

Black carbon and trace gases over South Asia: Measurements and Regional Climate model simulations

NASA Astrophysics Data System (ADS)

Bhuyan, Pradip; Pathak, Binita; Parottil, Ajay

2016-07-01

Trace gases and aerosols are simulated with 50 km spatial resolution over South Asian CORDEX domain enclosing the Indian sub-continent and North-East India for the year 2012 using two regional climate models RegCM4 coupled with CLM4.5 and WRF-Chem 3.5. Both models are found to capture the seasonality in the simulated O3 and its precursors, NOx and CO and black carbon concentrations together with the meteorological variables over the Indian Subcontinent as well as over the sub-Himalayan North-Eastern region of India including Bangladesh. The model simulations are compared with the measurements made at Dibrugarh (27.3°N, 94.6°E, 111 m amsl). Both the models are found to capture the observed diurnal and seasonal variations in O3 concentrations with maximum in spring and minimum in monsoon, the correlation being better for WRF-Chem (R~0.77) than RegCM (R~0.54). Simulated NOx and CO is underestimated in all the seasons by both the models, the performance being better in the case of WRF-Chem. The observed difference may be contributed by the bias in the estimation of the O3 precursors NOx and CO in the emission inventories or the error in the simulation of the meteorological variables which influences O3 concentration in both the models. For example, in the pre-monsoon and winter season, the WRF-Chem model simulated shortwave flux overestimates the observation by ~500 Wm-2 while in the monsoon and post monsoon season, simulated shortwave flux is equivalent to the observation. The model predicts higher wind speed in all the seasons especially during night-time. In the post-monsoon and winter season, the simulated wind pattern is reverse to observation with daytime low and night-time high values. Rainfall is overestimated in all the seasons. RegCM-CLM4.5 is found to underestimate rainfall and other meteorological parameters. The WRF-Chem model closely captured the observed values of black carbon mass concentrations during pre-monsoon and summer monsoon seasons, but

Measurements of reactive trace gases and variable O3 formation rates in some South Carolina biomass burning plumes

Treesearch

S. K. Akagi; R. J. Yokelson; I. R. Burling; S. Meinardi; I. Simpson; D. R. Blake; G. R. McMeeking; A. Sullivan; T. Lee; S. Kreidenweis; S. Urbanski; J. Reardon; D. W. T. Griffith; T. J. Johnson; D. R. Weise

2013-01-01

In October-November 2011 we measured trace gas emission factors from seven prescribed fires in South Carolina (SC), US, using two Fourier transform infrared spectrometer (FTIR) systems and whole air sampling (WAS) into canisters followed by gas- 5 chromatographic analysis. A total of 97 trace gas species were quantified from both airborne and ground-based sampling...

The measurement of trace emissions and combustion characteristics for a mass fire [Chapter 32

Treesearch

Ronald A. Susott; Darold E. Ward; Ronald E. Babbitt; Don J. Latham

1991-01-01

Concerns increase about the effects of emissions from biomass burning on global climate. While the burning of biomass constitutes a large fraction of world emissions, there are insufficient data on the combustion efficiency, emission factors, and trace gases produced in these fires, and on how these factors depend on the highly variable chemistry and burning condition...

EDITORIAL: Cold Quantum GasesEditorial: Cold Quantum Gases

NASA Astrophysics Data System (ADS)

Vassen, W.; Hemmerich, A.; Arimondo, E.

2003-04-01

This Special Issue of Journal of Optics B: Quantum and Semiclassical Optics brings together the contributions of various researchers working on theoretical and experimental aspects of cold quantum gases. Different aspects of atom optics, matter wave interferometry, laser manipulation of atoms and molecules, and production of very cold and degenerate gases are presented. The variety of subjects demonstrates the steadily expanding role associated with this research area. The topics discussed in this issue, extending from basic physics to applications of atom optics and of cold atomic samples, include: bulletBose--Einstein condensation bulletFermi degenerate gases bulletCharacterization and manipulation of quantum gases bulletCoherent and nonlinear cold matter wave optics bulletNew schemes for laser cooling bulletCoherent cold molecular gases bulletUltra-precise atomic clocks bulletApplications of cold quantum gases to metrology and spectroscopy bulletApplications of cold quantum gases to quantum computing bulletNanoprobes and nanolithography. This special issue is published in connection with the 7th International Workshop on Atom Optics and Interferometry, held in Lunteren, The Netherlands, from 28 September to 2 October 2002. This was the last in a series of Workshops organized with the support of the European Community that have greatly contributed to progress in this area. The scientific part of the Workshop was managed by A Hemmerich, W Hogervorst, W Vassen and J T M Walraven, with input from members of the International Programme Committee who are listed below. The practical aspects of the organization were ably handled by Petra de Gijsel from the Vrije Universiteit in Amsterdam. The Workshop was funded by the European Science Foundation (programme BEC2000+), the European Networks 'Cold Quantum Gases (CQG)', coordinated by E Arimondo, and 'Cold Atoms and Ultraprecise Atomic Clocks (CAUAC)', coordinated by J Henningsen, by the German Physical Society (DFG), by

Evaluation of the Giggenbach bottle method using artificial fumarolic gases

NASA Astrophysics Data System (ADS)

Lee, S.; Jeong, H. Y.

2013-12-01

Volcanic eruption is one of the most dangerous natural disasters. Mt. Baekdu, located on the border between North Korea and China, has been recently showing multiple signs of its eruption. The magmatic activity of a volcano strongly affects the composition of volcanic gases, which can provide a useful tool for predicting the eruption. Among various volcanic gas monitoring methods, the Giggenbach bottle method involves the on-site sampling of volcanic gases and the subsequent laboratory analysis, thus making it possible to detect a range of volcanic gases at low levels. In this study, we aim to evaluate the effectiveness of the Giggenbach bottle method and develop the associated analytical tools using artificial fumarolic gases with known compositions. The artificial fumarolic gases are generated by mixing CO2, CO, H2S, SO2, Ar, and H2 gas streams with a N2 stream sparged through an acidic medium containing HCl and HF. The target compositions of the fumarolic gases are selected to cover those reported for various volcanoes under different tectonic environments as follows: CO2 (2-12 mol %), CO (0.3-1 mol %), H2S (0.7-2 mol %), SO2 (0.6-4 mol %), Ar (0.3-0.7 mol %), H2 (0.3-0.7 mol %), HCl (0.2-1 mol %), and HF (< 0.015 mol %). The artificial fumarolic gases are collected into an evacuated bottle partially filled with 4 M NaOH solution containing 0.5 mM Cd(CH3COO)2. While non-condensable components such as CO, Ar, H2, and N2 accumulate in the headspace of the bottle, acidic components including CO2, SO2, HCl, and HF dissolve into the alkaline solution. In case of H2S, it reacts with dissolved Cd2+ to precipitate as CdS(s). The gas accumulated in the headspace can be analyzed for CO, Ar, H2, and N2 on a gas chromatography. The alkaline solution is first separated from yellowish CdS precipitates by filtration, and then pretreated with hydrogen peroxide to oxidize dissolved SO2 (H2SO3) to SO42-. The resultant solution can be analyzed for SO2 as SO42-, HCl as Cl-, and HF

Tracing Carbon Sources through Aquatic and Terrestrial Food Webs Using Amino Acid Stable Isotope Fingerprinting

PubMed Central

Larsen, Thomas; Ventura, Marc; Andersen, Nils; O’Brien, Diane M.; Piatkowski, Uwe; McCarthy, Matthew D.

2013-01-01

Tracing the origin of nutrients is a fundamental goal of food web research but methodological issues associated with current research techniques such as using stable isotope ratios of bulk tissue can lead to confounding results. We investigated whether naturally occurring δ13C patterns among amino acids (δ13CAA) could distinguish between multiple aquatic and terrestrial primary production sources. We found that δ13CAA patterns in contrast to bulk δ13C values distinguished between carbon derived from algae, seagrass, terrestrial plants, bacteria and fungi. Furthermore, we showed for two aquatic producers that their δ13CAA patterns were largely unaffected by different environmental conditions despite substantial shifts in bulk δ13C values. The potential of assessing the major carbon sources at the base of the food web was demonstrated for freshwater, pelagic, and estuarine consumers; consumer δ13C patterns of essential amino acids largely matched those of the dominant primary producers in each system. Since amino acids make up about half of organismal carbon, source diagnostic isotope fingerprints can be used as a new complementary approach to overcome some of the limitations of variable source bulk isotope values commonly encountered in estuarine areas and other complex environments with mixed aquatic and terrestrial inputs. PMID:24069196

Tracing carbon sources through aquatic and terrestrial food webs using amino acid stable isotope fingerprinting.

PubMed

Larsen, Thomas; Ventura, Marc; Andersen, Nils; O'Brien, Diane M; Piatkowski, Uwe; McCarthy, Matthew D

2013-01-01

Tracing the origin of nutrients is a fundamental goal of food web research but methodological issues associated with current research techniques such as using stable isotope ratios of bulk tissue can lead to confounding results. We investigated whether naturally occurring δ(13)C patterns among amino acids (δ(13)CAA) could distinguish between multiple aquatic and terrestrial primary production sources. We found that δ(13)CAA patterns in contrast to bulk δ(13)C values distinguished between carbon derived from algae, seagrass, terrestrial plants, bacteria and fungi. Furthermore, we showed for two aquatic producers that their δ(13)CAA patterns were largely unaffected by different environmental conditions despite substantial shifts in bulk δ(13)C values. The potential of assessing the major carbon sources at the base of the food web was demonstrated for freshwater, pelagic, and estuarine consumers; consumer δ(13)C patterns of essential amino acids largely matched those of the dominant primary producers in each system. Since amino acids make up about half of organismal carbon, source diagnostic isotope fingerprints can be used as a new complementary approach to overcome some of the limitations of variable source bulk isotope values commonly encountered in estuarine areas and other complex environments with mixed aquatic and terrestrial inputs.

Global Observations of Inorganic Gases in the Remote Atmosphere - First Observations from the Atmospheric Tomography Mission (ATom)

NASA Astrophysics Data System (ADS)

Veres, P. R.; Neuman, J. A.

2017-12-01

The Atmospheric Tomography Mission (ATom) is a NASA field program that investigates the impact of human emissions on air quality and climate in remote regions of the atmosphere. NASA DC-8 flights during the ATom sampled the atmosphere over the Pacific and Atlantic Oceans, up to 12 km altitude and nearly from pole to pole. New observations of key species (e.g. N2O5, reactive halogens, nitrous acid) in these regions are provided during the third deployment of the NASA DC-8 research aircraft (October, 2017) by the NOAA iodide ion time-of-flight chemical ionization mass spectrometer (iCIMS). In this study, we will present the first observations of inorganic gas-phase species using iCIMS from the ATom 3 deployment. Laboratory results detailing the instrument performance including inlet response times, background characterization and sensitivity will be presented. We will show vertical profiles of newly measured trace gases derived from in-situ observations, and discuss the potential impact on the NOx, NOy and reactive halogen budgets.

Rn-222 tracing and stable isotope measurements of biogenic gas fluxes from methane saturated sediments

NASA Technical Reports Server (NTRS)

Martens, Christopher S.; Green, C. D.; Blair, Neal; Chanton, J. P.

1985-01-01

Transport of reduced biogenic gases from anoxic sediments and soils to the atmosphere can be quantitatively studied through measurement of radon-222/radium-226 disequilibrium. In previous work, seasonal variations in biogenic gas transport mechanisms, net fluxes and overall composition were documented. Now presented are direct field measurements of radon-222 activity in gases exiting organic rich sediments which show their usefulness for tracing of the stripping of dissolved biogenic gases from within the sediment column and transport via bubble ebullition. Methane is depleted in deuterium during the summer as compared with winter months and is in general lighter than in most marine sediments signaling the probable importance of acetate as an important precursor molecule. The significant seasonal isotopic variations observed illustrate the importance of understanding mechanisms and rates of biogenic gas production in order to interpret observed tropospheric isotopic data.

Capture and release of mixed acid gasses with binding organic liquids

DOEpatents

Heldebrant, David J.; Yonker, Clement R.

2010-09-21

Reversible acid-gas binding organic liquid systems that permit separation and capture of one or more of several acid gases from a mixed gas stream, transport of the liquid, release of the acid gases from the ionic liquid and reuse of the liquid to bind more acid gas with significant energy savings compared to current aqueous systems. These systems utilize acid gas capture compounds made up of strong bases and weak acids that form salts when reacted with a selected acid gas, and which release these gases when a preselected triggering event occurs. The various new materials that make up this system can also be included in various other applications such as chemical sensors, chemical reactants, scrubbers, and separators that allow for the specific and separate removal of desired materials from a gas stream such as flue gas.

Control of Penicillium martensii Development and Penicillic Acid Production by Atmospheric Gases and Temperatures

PubMed Central

Lillehoj, E. B.; Milburn, M. S.; Ciegler, A.

1972-01-01

The effects of various gaseous environments and temperatures on development of Penicillium martensii NRRL 3612 and production of penicillic acid (PA) were determined. Accumulation of PA in mold-inoculated corn was measured following incubation under air; 20% CO2, 20% O2, 60% N2; 40% CO2, 20% O2, 40% N2; and 60% CO2, 20% O2, 20% N2. Although reduced temperature initially inhibited PA production, at the end of the trial the largest quantity of PA (120 μg/g of corn) was found in air-incubated corn at the lowest test temperature (5 C). Atmospheres enriched with 60% CO2 reduced PA accumulation below a detectable level at 5 and 10 C after a 4-week incubation period. Spore germination tests were carried out in a liquid growth medium incubated for 16 hr under several test conditions. Germ tube outgrowth at 30 C ranged from 36% in air to 2% in 60% CO2, whereas no germination was observed in CO2-enriched gases at 10 C. When spore respiration rates were measured in air and O2 in a liquid growth medium, complete removal of CO2 from the reaction atmosphere did not reduce O2 uptake. PMID:5071649

An aircraft compatible laser induced fluorescence system - In situ and remote measurements of trace gases

NASA Technical Reports Server (NTRS)

Davis, D. D.; Philen, D.

1978-01-01

The laser-induced fluorescence technique for obtaining direct measurements of atmospheric OH and other gases is described. A narrow-band UV laser is tuned to one or more of the electronic absorption bands of a specified molecule so as to cause fluorescence from a bonding excited electronic state. The monitored wavelength is longer than the laser wavelength. Equipment, specifics for OH detection, data processing, and interference are discussed, and application of the technique to the detection of NO, SO2, and CH2O is considered.

A mechanism for hydrochloric acid production in cloud

Treesearch

Glenn K. Yue; Volkar A. Mohnen; C. S. Kiang

1976-01-01

A theoretical model describing the general interaction between atmospheric trace gases, such as SO2, NH3, CO2 and O2, chemical reactant gaseous product H2SO4 and hydrometeors containing NaCl is proposed to study a possible mechanism...

Sensitive Multi-Species Emissions Monitoring: Infrared Laser-Based Detection of Trace-Level Contaminants

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

Steill, Jeffrey D.; Huang, Haifeng; Hoops, Alexandra A.

This report summarizes our development of spectroscopic chemical analysis techniques and spectral modeling for trace-gas measurements of highly-regulated low-concentration species present in flue gas emissions from utility coal boilers such as HCl under conditions of high humidity. Detailed spectral modeling of the spectroscopy of HCl and other important combustion and atmospheric species such as H 2 O, CO 2 , N 2 O, NO 2 , SO 2 , and CH 4 demonstrates that IR-laser spectroscopy is a sensitive multi-component analysis strategy. Experimental measurements from techniques based on IR laser spectroscopy are presented that demonstrate sub-ppm sensitivity levels to thesemore » species. Photoacoustic infrared spectroscopy is used to detect and quantify HCl at ppm levels with extremely high signal-to-noise even under conditions of high relative humidity. Additionally, cavity ring-down IR spectroscopy is used to achieve an extremely high sensitivity to combustion trace gases in this spectral region; ppm level CH 4 is one demonstrated example. The importance of spectral resolution in the sensitivity of a trace-gas measurement is examined by spectral modeling in the mid- and near-IR, and efforts to improve measurement resolution through novel instrument development are described. While previous project reports focused on benefits and complexities of the dual-etalon cavity ring-down infrared spectrometer, here details on steps taken to implement this unique and potentially revolutionary instrument are described. This report also illustrates and critiques the general strategy of IR- laser photodetection of trace gases leading to the conclusion that mid-IR laser spectroscopy techniques provide a promising basis for further instrument development and implementation that will enable cost-effective sensitive detection of multiple key contaminant species simultaneously.« less

Diurnal cycle of greenhouse gases and biogenic hydrocarbons during summer near Cool, CA

NASA Astrophysics Data System (ADS)

Flowers, B. A.; Floerchinger, C.; Knighton, W. B.; Dubey, M. K.; Herndon, S. C.; Kelley, P.; Luke, W. T.; Shaw, W. J.; Barnard, J.; Laulainen, N.; Zaveri, R. A.

2010-12-01

Photosynthesis by forests is a large sink for atmospheric carbon dioxide (CO2) and also a large source of biogenic volatile organics (VOCs) that produce aerosols, nucleate clouds, and interact with nitrogen oxides (NOx) to produce ozone. To elucidate these complex biogeochemical mechanisms, we performed continuous high temporal resolution measurements of CO2, VOC, trace gases, and aerosol in June 2010 at the T1 site, 70 km from Sacramento, CA, during the Carbonaceous Aerosol and Radiative Effects Study (CARES) in June 2010. Throughout the month we find that diurnal profiles exhibit minima in CO2 and maxima in isoprene during daytime. Both their amplitudes are modulated strongly by cloud cover consistent with a common photosynthetic mechanism. In contrast, we find that diurnal monoterpene profiles peak at night while CO2 is at its maxima. Their amplitudes are modulated by temperature and boundary layer height. The monoterpenes and CO2 cycle show larger increases at warmer temperatures, suggesting respiration as a common driver. Additional measurements of CH4, CO, benzene, toluene, NO, NOy and O3 are used to define biogeochemical cycling of greenhouse gases and are demonstrated as a baseline for separating anthropogenic and biogenic emissions and observing transport of greenhouse gases and air pollution.

Processes for converting lignocellulosics to reduced acid pyrolysis oil

DOEpatents

Kocal, Joseph Anthony; Brandvold, Timothy A

2015-01-06

Processes for producing reduced acid lignocellulosic-derived pyrolysis oil are provided. In a process, lignocellulosic material is fed to a heating zone. A basic solid catalyst is delivered to the heating zone. The lignocellulosic material is pyrolyzed in the presence of the basic solid catalyst in the heating zone to create pyrolysis gases. The oxygen in the pyrolysis gases is catalytically converted to separable species in the heating zone. The pyrolysis gases are removed from the heating zone and are liquefied to form the reduced acid lignocellulosic-derived pyrolysis oil.

Organic Halogen and Related Trace Gases in the Tropical Atmosphere: Results from Recent Airborne Campaigns Over the Pacific

NASA Astrophysics Data System (ADS)

Atlas, E. L.; Navarro, M. A.; Donets, V.; Schauffler, S.; Lueb, R.; Hendershot, R.; Gabbard, S.; Hornbrook, R. S.; Apel, E. C.; Riemer, D. D.; Pan, L.; Salawitch, R. J.; Nicely, J. M.; Montzka, S. A.; Miller, B.; Moore, F. L.; Elkins, J. W.; Hintsa, E. J.; Campos, T. L.; Quack, B.; Zhu, X.; Pope, L.

2014-12-01

Organic halogen gases, especially containing bromine and iodine, play a significant role as precursors to active halogen chemistry and ozone catalytic loss. Much of the reactive organic halogen originates from biological processes in the surface ocean, which can be quite variable by season and location. The tropics and coastal margins are potentially important sources that are being examined. The recent coordinated CONTRAST/ATTREX/CAST missions were conducted in the Western Tropical Pacific, a region that is a major transport pathway for tropospheric air entering the stratosphere. One of the goals of the missions was to identify sources, distributions, and transport of organic halogens from the ocean surface into the tropical lower stratosphere. The missions were conducted during the NH winter season, Jan-Feb, 2014. In this presentation, we will discuss the distributions and variability of organic halogen gases in the study region and will examine the input of organic halogen species into the Tropical Tropopause Layer (TTL). Comparison with other tracers, such as methyl nitrate and NMHC, will help identify source regions for these gases. We will focus on the measurements obtained in the CONTRAST and ATTREX missions with data from in-situ GC/MS measurements and whole air samples collected on the NSF GV and NASA Global Hawk aircraft. Comparisons with other recent airborne campaigns, such as HIPPO and TC4, and with several ship-based studies will provide an additional context for evaluating the variability of organic halogen species in the tropical atmosphere and their role in transporting reactive halogen compounds into the UT/LS.

Trace Gas Retrievals from the GeoTASO Aircraft Instrument

NASA Astrophysics Data System (ADS)

Nowlan, C. R.; Liu, X.; Leitch, J. W.; Liu, C.; Gonzalez Abad, G.; Chance, K.; Cole, J.; Delker, T.; Good, W. S.; Murcray, F.; Ruppert, L.; Soo, D.; Loughner, C.; Follette-Cook, M. B.; Janz, S. J.; Kowalewski, M. G.; Pickering, K. E.; Zoogman, P.; Al-Saadi, J. A.

2015-12-01

The Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) instrument is a passive remote sensing instrument capable of making 2-D measurements of trace gases and aerosols from aircraft. The instrument measures backscattered UV and visible radiation, allowing the retrieval of trace gas amounts below the aircraft at horizontal resolutions on the order of 250 m x 250 m. GeoTASO was originally developed under NASA's Instrument Incubator Program as a test-bed instrument for the Geostationary Coastal and Air Pollution Events (GEO-CAPE) decadal survey mission, and is now also part of risk reduction for the upcoming Tropospheric Emissions: Monitoring of Pollution (TEMPO) and Geostationary Environment Monitoring Spectrometer (GEMS) geostationary satellite missions. We present spatially resolved observations of ozone, nitrogen dioxide, formaldehyde and sulfur dioxide over urban areas and power plants from flights during the DISCOVER-AQ field campaigns in Texas and Colorado, as well as comparisons with observations made by ground-based Pandora spectrometers, in situ monitoring instruments and other aircraft instruments deployed during these campaigns. These measurements at various times of day are providing a very useful data set for testing and improving TEMPO and GEMS retrieval algorithms, as well as demonstrating prototype validation strategies.

Ultra-sensitive Trace-Water Optical Sensor with In situ- synthesized Metal-Organic Framework in Glass Paper.

PubMed

Ohira, Shin-Ichi; Nakamura, Nao; Endo, Masaaki; Miki, Yusuke; Hirose, Yasuo; Toda, Kei

2018-01-01

Monitoring of trace water in industrial gases is strongly recommended because contaminants cause serious problems during use, especially in the semiconductor industry. An ultra-sensitive trace-water sensor was developed with an in situ-synthesized metal-organic framework as the sensing material. The sample gas is passed through the sensing membrane and efficiently and rapidly collected by the sensing material in the newly designed gas collection/detection cell. The sensing membrane, glass paper impregnated with copper 1,3,5-benzenetricarboxylate (Cu-BTC), is also newly developed. The amount and density of the sensing material in the sensing membrane must be well balanced to achieve rapid and sensitive responses. In the present study, Cu-BTC was synthesized in situ in glass paper. The developed system gave high sensing performances with a limit of detection (signal/noise ratio = 3) of 9 parts per billion by volume (ppbv) H 2 O and a 90% response time of 86 s for 200 ppbv H 2 O. The reproducibility of the responses within and between lots had relative standard deviations for 500 ppbv H 2 O of 0.8% (n = 10) and 1.5% (n = 3), respectively. The long-term (2 weeks) stability was 7.3% for 400 ppbv H 2 O and one-year continuous monitoring test showed the sensitivity change of <∼3% before and after the study. Furthermore, the system response was in good agreement with the response achieved in cavity ring-down spectroscopy. These performances are sufficient for monitoring trace water in industrial gases. The integrated system with light and gas transparent structure for gas collection/absorbance detection can also be used for other target gases, using specific metal-organic frameworks.

Flux measurements of energy and trace gases in urban Houston, Texas

NASA Astrophysics Data System (ADS)

Boedeker, I.; Schade, G. W.; Adams, S.; Park, C.

2008-12-01

We describe the setup and some first year results of a new flux measurements tower in an urban area. An existing radio communications tower 4 km north of downtown Houston was equipped with micrometeorological instrumentation and trace gas sampling lines in spring 2007. Wind speed, temperature and relative humidity are recorded at five levels between 12 and 60 m above ground; 3-D wind speed measurements, solar and net radiances, and trace gas sampling are established from the 60 m level. A closed path IRGA is used for CO2 and water vapor fluxes, and independent instrumentation for criteria pollutant and VOC fluxes. Two CSI data loggers and software control the measurements, and EdiRe software is used to analyze turbulence data and compute fluxes. A project description is provided at http://atmo.tamu.edu/yellowcabtower. Surface properties as calculated from the gradient measurements show the site to be surprisingly uniform, with displacement heights between 5 and 9 m and roughness lengths between 0.4 and 0.7 m, despite urban heterogeneity. The latter is investigated through visible/near IR orthoimagery and LIDAR data, which are incorporated into a local GIS. Net radiation was also only marginally affected by surface heterogeneity. At this urban location it is balanced by roughly equal amounts of sensible heat, latent heat, and storage fluxes. Latent heat flux, however, is smaller outside the growing season, with an equivalent increase in winter storage fluxes, as expected. Significant differences are also observed with direction during summer, showing decreased Bowen ratios and lower CO2 emissions from sectors with a larger urban tree canopy cover in the footprint. The largely mature, dominantly oak urban canopy cover alleviates approximately 100 W m- 2 during typical summer days. On the other hand, anthropogenic CO2 emissions dominate over photosynthetic uptake all year round. Measured carbon fluxes peak during morning rush-hour traffic, especially when increasing

Measurements of reactive trace gases and variable O3 formation rates in some South Carolina biomass burning plumes [Discussions

Treesearch

S. K. Akagi; R. J. Yokelson; I. R. Burling; S. Meinardi; I. Simpson; D. R. Blake; G. R. McMeeking; A. Sullivan; T. Lee; S. Kreidenweis; S. Urbanski; J. Reardon; D. W. T. Griffith; T. J. Johnson; D. R. Weise

2012-01-01

In October–November 2011 we measured trace gas emission factors from seven prescribed fires in South Carolina (SC), US, using two Fourier transform infrared spectrometer (FTIR) systems and whole air sampling (WAS) into canisters followed by gas-chromatographic analysis. A total of 97 trace gas species were quantified from both airborne and ground-based sampling...

Measurements of Gases and Aerosols during 2010Cal-Mex

NASA Astrophysics Data System (ADS)

Zheng, J.; Zhang, R.; Molina, L.

2012-04-01

The major goal of the collaborative Cal-Mex 2010 research project is to assess the sources and processing of emissions along the California-Mexico border region and their effects on regional air quality and climate in order to provide scientific information to decision makers of both nations when addressing these two inter-related issues. During the Cal-Mex 2010 field study, the TAMU teams have collected extensive data sets from Tijuana/San Diego border, including volatile organic compounds (VOCs), gaseous sulfuric acid (H2SO4) and a suite set of physical and chemical parameters of aerosols. This comprehensive data set requires additional effort to process and analyze the measurements of gases and aerosols during Cal-Mex 2010. In this talk, preliminary data analysis of gases and aerosols will be presented, including VOCs and particle mixing states, morphology, and effective densities.

Pollution evaluation of total and acid-leachable trace elements in surface sediments of Hooghly River Estuary and Sundarban Mangrove Wetland (India).

PubMed

Mondal, Priyanka; Reichelt-Brushett, Amanda J; Jonathan, M P; Sujitha, S B; Sarkar, Santosh Kumar

2018-02-01

The present work investigated the spatial distribution and ecological risk assessment of total and mild acid-leachable trace elements in surface sediments (top 0-10 cm; grain size ≤ 63 μm) along the Hooghly (Ganges) River Estuary and Sundarban Mangrove Wetland, India. The trace elements, analyzed by ICPMS, showed wide range of variations with the following descending order (mean values expressed in milligrams per kilogram): Fe (25,050 ± 4918) > Al (16,992 ± 4172) > Mn (517 ± 102) > Zn (53 ± 18) > Cu (33 ± 11) > Cr (29 ± 7) > Ni (27 ± 6) > Pb (14 ± 3) > As (5 ± 1) > Se (0.37 ± 0.10) > Cd (0.17 ± 0.13) > Ag (0.16 ± 0.19) > Hg (0.05 ± 0.10). In the acid-leachable fraction, Cd (92%) is dominated followed by Pb (81%), Mn (77%), Cu (70%), and Se (58%) indicating their high mobility, imposing negative impact on the adjacent benthos. The sediment pollution indices (both enrichment factor and contamination factor) suggested severe pollution by Ag at the sampling site Sajnekhali, a wildlife sanctuary in Sundarban. The mean probable effect level quotient indicated that surface sediments in the vicinity of the studied region have 21% probability of toxicity to biota. The result of multivariate analyses affirms lithogenic sources (e.g., weathering parent rocks, dry deposition) for As, Pb, Cr, Cu, and Ni, whereas Cd and Hg originated from anthropogenic activities (such as urban and industrial activities). Both human-induced stresses and natural processes controlled trace element accumulation and distribution in the estuarine system, and remedial measures are required to mitigate the potential impacts of these hazardous trace elements.

Planning studies for measurement of chemical emissions in stack gases of coal-fired power plants. Final report

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

Barrett, W.J.; Gooch, J.P.; Dahlin, R.S.

1983-03-01

Airborne emissions from coal-fired power plants consist of sulfur, nitrogen, and carbon oxides, as well as traces of certain metals or elements, radionuclides, and organic compounds that have the potential of producing adverse health effects if inhaled. To assess this potential toxicity, samples must be obtained and characterized on the basis of quantity, their chemistry, and toxicity. Sample representativeness and use of proper chemical-biological procedures are the critical for providing input into current research directed toward source apportionment and inhalation toxicology. Obtaining a valid stack sample (gases and particles) from each of more than 1500 US coal-fired power plant ismore » not practical; consequently 33 plants have been selected, taking into account plant design and operating parameters that can affect the characteristics of stack chemical emissions. Since such a program has an estimated cost of $20 million over many years, it is recommended that the initial program consists of sampling only six of the 33 units, selected with EPRI guidance, at an estimated cost of $3.5 million over a 30 month period. The plan is directed at in-stack sampling, plume and atmospheric transformations being beyond the project scope. Various stack sampling methods are considered. For particles, a modified SASS train seems best, and for gases, either resin traps or impingers are probably best. Artifact formation must be minimized. Chemical analysis procedures are to be guided by the known toxicity of species present. Procedures are outlined for organics (volatile and nonvolatile), trace elements, inorganics, and gases. Bioassay methods are restricted to in vitro, subdivided into those assays that detect genetic and direct cellular toxicity.« less

46 CFR 194.15-17 - Compressed gases other than inert gases.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Compressed gases other than inert gases. 194.15-17 Section 194.15-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS HANDLING, USE, AND CONTROL OF EXPLOSIVES AND OTHER HAZARDOUS MATERIALS Chemistry Laboratory and...

46 CFR 194.15-17 - Compressed gases other than inert gases.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 7 2013-10-01 2013-10-01 false Compressed gases other than inert gases. 194.15-17 Section 194.15-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS HANDLING, USE, AND CONTROL OF EXPLOSIVES AND OTHER HAZARDOUS MATERIALS Chemistry Laboratory and...

Sources and sinks of selected trace gases in the tropospheric boundary layer of the eastern United States

NASA Astrophysics Data System (ADS)

White, Marguerite L.

This dissertation describes three major research projects with the common goal of characterizing sources and sinks of trace gases of strong relevance to regional air quality and global climate issues. In the first study, volatile organic compound (VOC) measurements collected at a marine and continental site in northern New England were compared and examined for evidence of regional VOC sources. Biogenic VOCs, including isoprene, monoterpenes, and oxygenated VOCs, were significant components of the total reactivity at both locations. However, very different VOC distributions were observed for each site. The impact of local anthropogenic hydrocarbon sources such as liquefied petroleum gas (LPG) leakage was also evident at both sites. During the campaign, a propane flux of 9 (+/-2) x 109 molecules cm-2 s-1 was calculated for the continental site. In the second study, three hydrocarbon sources were investigated for their potential contributions to the summertime atmospheric toluene enhancements observed at a rural location in southern New Hampshire. These sources included: (1) warm season fuel evaporation emissions, (2) local industrial emissions, and (3) local vegetative emissions. The estimated contribution of fuel evaporation emissions (16-30 pptv d-1) could not fully account for observed summertime toluene enhancements (20-50 pptv d-1). Vegetation enclosure measurements suggested biogenic toluene emissions (5 and 12 pptv d-1 for alfalfa and pine trees) made significant contributions to summertime enhancements. Industrial toluene emissions, estimated at 7 pptv d-1, most likely occurred year round rather than seasonally. Finally, controls over carbonyl sulfide (COS) uptake in a temperate loblolly pine forest grown under ambient and elevated CO2 were examined in the third study. Vegetative consumption dominated net ecosystem COS uptake (10 to 40 pmol m-2 s-1) under both CO2 regimes. Environmental controls over vegetation stomatal conductance and photosynthetic

Application of a broadly tunable SG-DBR QCL for multi-species trace gas spectroscopy.

PubMed

Diba, Abdou S; Xie, Feng; Gross, Barry; Hughes, Lawrence C; Zah, Chung-en; Moshary, Fred

2015-10-19

Feasibility of using a mid-Infrared tunable sampled-grating distributed Bragg reflectors quantum cascade laser for high resolution multicomponent trace gas spectroscopy is demonstrated. By controlling the driving currents to the front and back sections of the laser, we were able to tune a pulsed 4.55 µm laser over a frequency range a of 30 cm(-1) with high resolution, accuracy and repeatability. The laser was applied to absorption spectroscopy of ambient and reduced pressure (150 Torr) air in a 205 meters multi-pass Herriott cell, and by using standard LSQ fitting to a spectral database of these trace gases (HITRAN), the concentrations of nitrous oxide, carbon monoxide, and water vapor were retrieved.

What Is Acid Rain?

ERIC Educational Resources Information Center

Likens, Gene E.

2004-01-01

Acid rain is the collective term for any type of acidified precipitation: rain, snow, sleet, and hail, as well as the presence of acidifying gases, particles, cloud water, and fog in the atmosphere. The increased acidity, primarily from sulfuric and nitric acids, is generated as a by-product of the combustion of fossil fuels such as coal and oil.…

Annular denuders for use in global climate and stratospheric measurements of acidic gases and particles

NASA Technical Reports Server (NTRS)

Stevens, Robert K.

1991-01-01

Measurements of acidic and basic gases that coexist with fine particle (less than 2.5 micron) may be useful for determining the impact of these species on global climate changes and determining species that influence stratospheric ozone levels. Annular denuders are well suited for this purpose. A new concentric annular denuder system, consisting of a three channel denuder, a Teflon coated cyclone preseparator, and a multistage filter pack was developed, evaluated, and shown to provide reliable atmospheric measurements of SO2, HNO2, HNO3, NH3, SO4(=), NH4(+), NO3(-), and H(+). For example, the precision of the annular denuder for the ambient measurements of HNO3 and nitrates at concentrations between 0.1 to 3 microgram/cu m was + or - 12 and 16 pct., respectively. The 120 x 25 mm three channel denuder is encased in a stainless steel sheath and has annular spaces that are 1 mm wide. This design was shown to have nearly identical capacity for removal of SO2 as conventional 210 x 25 mm single channel denuder configurations. The cyclone preseparator was designed and tested to have a D sub 50 cutoff diameter of 2.5 micron and minimal retention of HNO3.

Simultaneous removal of nitrogen oxides and sulfur oxides from combustion gases

DOEpatents

Clay, David T.; Lynn, Scott

1976-10-19

A process for the simultaneous removal of sulfur oxides and nitrogen oxides from power plant stack gases comprising contacting the stack gases with a supported iron oxide catalyst/absorbent in the presence of sufficient reducing agent selected from the group consisting of carbon monoxide, hydrogen, and mixtures thereof, to provide a net reducing atmosphere in the SO.sub.x /NO.sub.x removal zone. The sulfur oxides are removed by absorption substantially as iron sulfide, and nitrogen oxides are removed by catalytic reduction to nitrogen and ammonia. The spent iron oxide catalyst/absorbent is regenerated by oxidation and is recycled to the contacting zone. Sulfur dioxide is also produced during regeneration and can be utilized in the production of sulfuric acid and/or sulfur.

Essential trace elements and antioxidant status in relation to severity of HIV in Nigerian patients.

PubMed

Olaniyi, J A; Arinola, O G

2007-01-01

This study was designed to determine the plasma levels of some antioxidants and trace elements in three severity groups of HIV patients compared with non-HIV-infected controls. The plasma levels of antioxidants (total antioxidant, albumin, bilirubin and uric acid) and trace elements (Mg, Fe, Zn, Mn, Cu, Cr, Cd and Se) were estimated spectrophotometrically in controls and patients with CD4 counts of <200; 200-499 and > or =500 cells/microl. Uric acid and Zn were significantly higher, while vitamin E and all the trace elements (except Zn) were significantly lower in HIV-infected patients compared to healthy controls. The highest level of uric acid was observed in those with CD4 counts of <200 cells/microl. All the trace elements (except Zn) were higher in HIV subjects with a CD4 count of 200-499 cells/microl compared to >500 cells/microl. Only uric acid and Zn showed significant correlation with CD4 count. Based on the results of this study, we recommend routine assessment and appropriate supplementation of antioxidants/trace elements in HIV subjects. This supplementation is hoped to strengthen the immune system and reduce the adverse consequences of HIV- related oxidative stress. Copyright 2007 S. Karger AG, Basel.

Long Open Path Fourier Transform Spectroscopy Measurements of Greenhouse Gases in the Near Infrared

NASA Astrophysics Data System (ADS)

Griffith, D. W. T.

2015-12-01

Atmospheric composition measurements are an important tool to quantify local and regional emissions and sinks of greenhouse gases. Most in situ measurements are made at a point, but how representative are such measurements in an inhomogeneous environment? Open path Fourier Transform Spectroscopy (FTS) measurements potentially offer spatial averaging and continuous measurements of several trace gases (including CO2, CH4, CO and N2O) simultaneously in the same airmass. Spatial averaging over kilometre scales is a better fit to the finest scale atmospheric models becoming available, and helps bridge the gap between models and in situ measurements. In this paper we assess the precision, accuracy and reliability of long open path measurements by Fourier Transform Spectroscopy in the near infrared from a 5-month continuous record of measurements over a 1.5 km pathlength. Direct open-atmosphere measurements of trace gases CO2, CH4, CO and N2O as well as O2 were retrieved from several absorption bands between 4000 and 8000 cm-1 (2.5 - 1.25 micron). At one end of the path an in situ FTIR analyser simultaneously collected well calibrated measurements of the same species for comparison with the open path-integrated measurements. The measurements ran continuously from June - November 2014. We introduce the open path FTS measurement system and present an analysis of the results, including assessment of precision, accuracy relative to co-incident in situ measurements, reliability. Short term precision of the open path measurement of CO2 was better than 1 ppm for 5 minute averages and thus sufficient for studies in urban and other non-background environments. Measurement bias relative to calibrated in situ measurements was stable across the measurement period. The system operated reliably with data losses mainly due to weather events such as rain and fog preventing transmission of the IR beam. In principle the system can be improved to provide longer pathlengths and higher

The Significance of Acid Alteration in the Los Humeros High-Temperature Geothermal Field, Puebla, Mexico.

NASA Astrophysics Data System (ADS)

Elders, W. A.; Izquierdo, G.

2014-12-01

The Los Humeros geothermal field is a high-enthalpy hydrothermal system with more than 40 drilled deep wells, mostly producing high steam fractions at > 300oC. However, although it has a large resource potential, low permeability and corrosive acid fluids have hampered development so that it currently has an installed electrical generating capacity of only 40 MWe. The widespread production of low pH fluids from the reservoir is inconsistent with the marked absence in the reservoir rocks of hydrothermal minerals typical of acid alteration. Instead the hydrothermal alteration observed is typical of that due to neutral to alkaline pH waters reacting with the volcanic rocks of the production zones. Thus it appears that since the reservoir has recently suffered a marked drop in fluid pressure and is in process of transitioning from being water-dominated to being vapor-dominated. However sparse examples of acid leaching are observed locally at depths of about 2 km in the form of bleached, intensely silicified zones, in low permeability and very hot (>350oC) parts of reservoir. Although these leached rocks retain their primary volcanic and pyroclastic textures, they are altered almost entirely to microcrystalline quartz, with some relict pseudomorphs of plagioclase phenocrysts and traces of earlier-formed hydrothermal chlorite and pyrite. These acid-altered zones are usually only some tens of meters thick and deeper rocks lack such silicification. The acid fluids responsible for their formation could either be magmatic volatiles, or could be formed during production (e.g. reaction of water and salts forming hydrogen chloride by hydrolysis at high temperatures). The very high boron content of the fluids produced by the Los Humeros wells suggests that their ultimate source is most likely magmatic gases. However, these acid gases did not react widely with the rocks. We suggest that the silicified zones are forming locally where colder descending waters are encountering

Tropospheric chemistry over the lower Great Plains of the United States. 2. Trace gas profiles and distributions

NASA Astrophysics Data System (ADS)

Luke, Winston T.; Dickerson, Russell R.; Ryan, William F.; Pickering, Kenneth E.; Nunnermacker, Linda J.

1992-12-01

Convective clouds and thunderstorms redistribute air pollutants vertically, and by altering the chemistry and radiative balance of the upper troposphere, these local actions can have global consequences. To study these effects, measurements of trace gases ozone, O3, carbon monoxide, CO, and odd nitrogen were made aboard the NCAR Sabreliner on 18 flights over the southern Great Plains during June 1985. To demonstrate chemical changes induced by vertical motions in the atmosphere and to facilitate comparison with computer model calculations, these data were categorized according to synoptic flow patterns. Part 1 of this two-part paper details the alternating pulses of polar and maritime air masses that dominate the vertical mixing in this region. In this paper, trace gas measurements are presented as altitude profiles (0-12 km) with statistical distributions of mixing ratios for each species in each flow pattern. The polar flow regime is characterized by northwesterly winds, subsiding air, and convective stability. Concentrations of CO and total odd nitrogen (NOy) are relatively high in the shallow planetary boundary layer (PBL) but decrease rapidly with altitude. Ozone, on the other hand, is uniformly distributed, suggesting limited photochemical production; in fact, nitric oxide, NO, mixing ratios fell below 10 ppt (parts per 1012 by volume) in the midtroposphere. The maritime regime is characterized by southerly surface winds, convective instability, and a deep PBL; uniformly high concentrations of trace gases were found up to 4 km on one flight. Severe storms occur in maritime flow, especially when capped by a dry layer, and they transport large amounts of CO, O3, and NOy into the upper troposphere. Median NO levels at high altitude exceeded 300 ppt. Lightning produces spikes of NO (but not CO) with mixing ratios sometimes exceeding 1000 ppt. This flow pattern tends to leave the midtroposphere relatively clean with concentrations of trace gases similar to those

Recent Experimental Advances to Determine (noble) Gases in Waters

NASA Astrophysics Data System (ADS)

Kipfer, R.; Brennwald, M. S.; Huxol, S.; Mächler, L.; Maden, C.; Vogel, N.; Tomonaga, Y.

2013-12-01

In aquatic systems noble gases, radon, and bio-geochemically conservative transient trace gases (SF6, CFCs) are frequently applied to determine water residence times and to reconstruct past environmental and climatic conditions. Recent experimental breakthroughs now enable ● to apply the well-established concepts of terrestrial noble gas geochemistry in waters to the minute water amounts stored in sediment pore space and in fluid inclusions (A), ● to determine gas exchange processes on the bio-geochemical relevant time scales of minutes - hours (B), and ● to separate diffusive and advective gas transport in soil air (C). A. Noble-gas analysis in water samples (< 1 g) facilitates determining the solute transport in the pore space and identifying the origin of bio- and geogenic fluids in (un) consolidated sediments [1]. Advanced techniques that combine crushing and sieving speleothem samples in ultra-high-vacuum to a specific grain size allow to separate air and water-bearing fluid inclusions and thus enables noble-gas-based reconstruction of environmental conditions from water masses as small as 1mg [2]. B. The coupling of noble gas analysis with approaches of gas chromatography permits combined analysis of noble gases and other gases species (e.g., SF6, CFCs, O2, N2) from a single water sample. The new method substantially improves ground water dating by SF6 and CFCs as excess air is quantified from the same sample and hence can adequately be corrected for [3]. Portable membrane-inlet mass spectrometers enable the quasi-continuous and real-time analysis of noble gases and other dissolved gases directly in the field, allowing, for instance, quantification of O2 turnover rates on small time scales [4]. C. New technical developments perfect 222Rn analysis in water by the synchronous the determination of the short-lived 220Rn. The combined 220,222Rn analysis sheds light on the emanation behaviour of radon by identifying soil water content to be the crucial

[Analysis of Multiplatform CO (Carbon Monoxide) Measurements During Trace-P Mission

NASA Technical Reports Server (NTRS)

Pougatchev, Nikita S.

2004-01-01

Carbon monoxide is considered mission critical (TRACE-P NRA) because it is one of the gases involved in controlling the oxidizing power of the atmosphere and, as a tracer gas, is valuable in interpreting mission data sets. Carbon monoxide exhibits interannual differences, suggesting relatively short-term imbalances in sources and sinks. Sources of CO are dominated by fossil fuel combustion, biomass burning, and the photochemical oxidation of CH4 and nonmethane hydrocarbons while reaction with OH is believed to be the major sink for atmospheric CO, with additional losses due to soil uptake. Uncertainties in the magnitude and distribution of both sources and sinks remain fairly large however, and additional data are required to refine the global budget. Seasonal changes and a northern hemispheric latitudinal gradient have been described for a variety of Pacific basin sites through long-term monitoring of surface background levels. Latitudinal variations have also recently been described at upper tropospheric altitudes over a multi-year period by. TRACE-P will provide an aircraft survey of CO over the northern Pacific in the northern spring when CO concentrations are at their seasonal maximum in the northern hemisphere (NH) and at their seasonal minimum in the southern hemisphere (SH). Previous GTE missions, Le., PEM West-B and PEM Tropics-B, ground-based, and satellite observations (MAPS, April 1994) give us a general picture of the distribution of CO over the northern Pacific during this season. Based on these measurements, background CO levels over remote ocean areas are anticipated to be in the range of 110 - 180 ppbv, while those closer to the Asian continent may rise as high as 600 ppbv. These measurements also reveal high spatial variability (both horizontal and vertical) as well as temporal variations in CO over the area planned for the TRACE-P mission. This variability is a result of multiple CO sources, the meteorological complexity of transport processes

Atomistic simulation of mineral-melt trace-element partitioning

NASA Astrophysics Data System (ADS)

Allan, Neil L.; Du, Zhimei; Lavrentiev, Mikhail Yu.; Blundy, Jon D.; Purton, John A.; van Westrenen, Wim

2003-09-01

We discuss recent advances in computational approaches to trace-element incorporation in minerals and melts. It is crucial to take explicit account of the local structural environment of each ion in the solid and the change in this environment following the introduction of a foreign atom or atoms. Particular attention is paid to models using relaxation (strain) energies and solution energies, and the use of these different models for isovalent and heterovalent substitution in diopside and forsterite. Solution energies are also evaluated for pyrope and grossular garnets, and pyrope-grossular solid solutions. Unfavourable interactions between dodecahedral sites containing ions of the same size and connected by an intervening tetrahedron lead to larger solubilities of trace elements in the garnet solid solution than in either end member compound and to the failure of Goldschmidt's first rule. Our final two examples are the partitioning behaviour of noble gases, which behave as 'ions of zero charge' and the direct calculation of high-temperature partition coefficients between CaO solid and melt via Monte Carlo simulations.

Do Chemistry-Climate Models Project the Same Greenhouse Gas Chemistry if Initialized with Observations of the Trace Gases: A Pre-ATom Test

NASA Astrophysics Data System (ADS)

Flynn, C. M.; Prather, M. J.; Zhu, X.; Strode, S. A.; Steenrod, S. D.; Strahan, S. E.; Lamarque, J. F.; Fiore, A. M.; Horowitz, L. W.; Mao, J.; Murray, L. T.; Shindell, D. T.

2016-12-01

Experience with climate and chemistry model intercomparison projects (MIPs) has demonstrated a diversity in model projections for the chemical greenhouse gases CH4 and O3, even when forced by the same emissions. In general, the MIPs show that models diverge in the distribution of the many key trace species that control the reactivity of the troposphere (defined here as the loss of CH4 and the production and loss of O3). Two possible sources of model differences are the chemistry-transport coupling that creates the pattern of the essential precursor species, and the calculation of reactivity. Suppose that observations, such as those planned by NASA's Atmospheric Tomography (ATom) mission, provide us with enough of a chemical climatology to constrain the modeled distribution of the essential chemical species for the current epoch. Would the models calculate the same reactivity? ATom uses the DC-8 to make in situ measurements slicing through the middle of the Pacific and Atlantic Ocean basins each season and measuring the essential trace species. Unfortunately, ATom measurements will not be available until mid-2017. Here we take the baseline chemistry from one model version (as pseudo-observations) and use it to initialize 6 other global chemistry models. In this pre-ATom MIP, we take the full chemical composition for meridional slices centered on the Dateline (UC Irvine Chemistry-Transport Model, 0.6 deg resolution, 30 layers in the troposphere). We use grid cells between 0.5 and 12 km from 60 S to 60 N to initialize grid cells in the other six models (GEOS-Chem, GFDL-AM3, GISS ModelE2, GSFC GMI, NCAR, UCI CTM). The models are then integrated for 1 day and the key chemical rates (CH4, O3) are saved. These simulations assume that the initialized parcels remain unmixed over the 24 hours, and, hence, model-to-model variations will be due to differences in photochemistry, including clouds. In addition, we assess the relative importance of the precursor species by running

Sensory Detection and Responses to Toxic Gases

PubMed Central

Bessac, Bret F.; Jordt, Sven-Eric

2010-01-01

The inhalation of reactive gases and vapors can lead to severe damage of the airways and lung, compromising the function of the respiratory system. Exposures to oxidizing, electrophilic, acidic, or basic gases frequently occur in occupational and ambient environments. Corrosive gases and vapors such as chlorine, phosgene, and chloropicrin were used as warfare agents and in terrorist acts. Chemical airway exposures are detected by the olfactory, gustatory, and nociceptive sensory systems that initiate protective physiological and behavioral responses. This review focuses on the role of airway nociceptive sensory neurons in chemical sensing and discusses the recent discovery of neuronal receptors for reactive chemicals. Using physiological, imaging, and genetic approaches, Transient Receptor Potential (TRP) ion channels in sensory neurons were shown to respond to a wide range of noxious chemical stimuli, initiating pain, respiratory depression, cough, glandular secretions, and other protective responses. TRPA1, a TRP ion channel expressed in chemosensory C-fibers, is activated by almost all oxidizing and electrophilic chemicals, including chlorine, acrolein, tear gas agents, and methyl isocyanate, the highly noxious chemical released in the Bhopal disaster. Chemicals likely activate TRPA1 through covalent protein modification. Animal studies using TRPA1 antagonists or TRPA1-deficient mice confirmed the role of TRPA1 in chemically induced respiratory reflexes, pain, and inflammation in vivo. New research shows that sensory neurons are not merely passive sensors of chemical exposures. Sensory channels such as TRPA1 are essential for maintenance of airway inflammation in asthma and may contribute to the progression of airway injury following high-level chemical exposures. PMID:20601631

Dynamic Sampling of Trace Contaminants During the Mission Operations Test of the Deep Space Habitat

NASA Technical Reports Server (NTRS)

Monje, Oscar; Valling, Simo; Cornish, Jim

2013-01-01

The atmospheric composition inside spacecraft during long duration space missions is dynamic due to changes in the living and working environment of crew members, crew metabolism and payload operations. A portable FTIR gas analyzer was used to monitor the atmospheric composition within the Deep Space Habitat (DSH) during the Mission Operations Test (MOT) conducted at the Johnson Space Center (JSC). The FTIR monitored up to 20 gases in near- real time. The procedures developed for operating the FTIR were successful and data was collected with the FTIR at 5 minute intervals. Not all the 20 gases sampled were detected in all the modules and it was possible to measure dynamic changes in trace contaminant concentrations that were related to crew activities involving exercise and meal preparation.

Assessment of 28 trace elements and 17 amino acid levels in muscular tissues of broiler chicken (Gallus gallus) suffering from arsenic trioxide.

PubMed

Li, Si-Wen; He, Ying; Zhao, Hong-Jing; Wang, Yu; Liu, Juan-Juan; Shao, Yi-Zhi; Li, Jing-Lun; Sun, Xiao; Zhang, Li-Na; Xing, Ming-Wei

2017-10-01

The contents of 28 trace elements, 17 amino acid were evaluated in muscular tissues (wings, crureus and pectoralis) of chickens in response to arsenic trioxide (As 2 O 3 ). A total of 200 one-day-old male Hy-line chickens were fed either a commercial diet (C-group) or an As 2 O 3 supplement diet containing 7.5mg/kg (L-group), 15mg/kg (M-group) or 30mg/kg (H-group) As 2 O 3 for 90 days. The elements content was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Under As 2 O 3 exposure, the concentration of As were elevated 8.87-15.76 fold, 7.93-15.63 fold and 5.94-12.45 fold in wings, crureus and pectoralis compared to the corresponding C-group, respectively. 19 element levels (lithium (Li), magnesium (Mg), aluminum (Al), silicon (Si), kalium (K), vanadium (V), chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu), selenium (Se), strontium (Sr), molybdenum (Mo), cadmium (Cd), tin (Sn), antimony (Sb), barium (Ba), mercury (Hg) and lead (Pb), 9 element levels (K, Co, Ni, Cu, As, Se, Sr, Sn, Ba and Hg) and 4 element levels (Mn, cobalt (Co), As, Sr and Ba) were significantly increased (P < 0.05) in wing, crureus and pectoralis, respectively. 2 element levels (sodium (Na) and zinc (Zn)), 5 element levels (Li, Na, Si, titanium (Ti and Cr), 13 element levels (Li, Na, Mg, K, V, Cr, iron (Fe), Cu, Zn, Mo, Sn, Hg and Pb) were significantly decreased (P < 0.05) in wing muscle, crureus and pectoralis, respectively. Additionally, in crureus and pectoralis, the content of total amino acids (TAA) was no significant alterations in L and M-group and then increased approximately 10.2% and 7.6% in H-group, respectively (P < 0.05). In wings, the level of total amino acids increased approximately 10% in L-group, whereas it showed unchanged in M and H-group compared to the corresponding C-group. We also observed that significantly increased levels of proline, cysteine, aspartic acid, methionine along with decrease in the tyrosine levels in muscular tissues compared to

Airborne Measurements and Emission Estimates of Greenhouse Gases and Other Trace Constituents From the 2013 California Yosemite Rim Wildfire

NASA Technical Reports Server (NTRS)

Yates, E. L.; Iraci, L. T.; Singh, H. B.; Tanaka, T.; Roby, M. C.; Hamill, P.; Clements, C. B.; Lareau, N.; Contezac, J.; Blake, D. R.;

Differences in the concentrations of atmospheric trace gases in and above the tropical boundary layer

NASA Technical Reports Server (NTRS)

Rasmussen, R. A.; Khalil, M. A. K.

1981-01-01

Weekly air samples were collected at Cape Kumakahi (0 km) and at nearby Mauna Loa Observatory (3.4 km) which is above the boundary layer. EC/GC and GC/FID techniques were used to measure CH3I, CHCl3, CO and CH4 which are largely natural in origin, and C2Cl4, CCl4, CH3CCl3, (F-11), CCl2F2, (F-12), CHClF, (F-22) and C2F3Cl3 (F-113), which are due to anthropogenic (CCl3F) etc. activities. It was found that all these gases are significantly (alpha is equal to or less than 0.05) more abundant in the boundary layer than above it.

Oxygen buffering of Kilauea volcanic gases and the oxygen fugacity of Kilauea basalt

USGS Publications Warehouse

Gerlach, T.M.

1993-01-01

Volcanic gases collected during episode 1 of the Puu Oo eruption along the east rift zone of Kilauea Volcano, Hawaii, have uniform C-O-H-S-Cl-F compositions that are sharply depleted in CO2. The CO2-poor gases are typical of Type II volcanic gases (gerlach and Graeber, 1985) and were emitted from evolved magma stored for a prolonged period of time in the east rift zone after releasing CO2-rich gases during an earlier period of temporary residence in the summit magma chamber. The samples are remarkably free of contamination by atmospheric gases and meteoric water. Thermodynamic evaluation of the analytical data shows that the episode 1 gases have equilibrium compositions appropriate for temperatures between 935 and 1032??C. Open- and closed-system equilibrium models of species distributions for the episode 1 gases show unequivocally that coexisting lavas buffered the gas oxygen fugacities during cooling. These models indicate that the fO2 buffering process occurs by transfer of oxygen from the major species in the gas phase (H2O, CO2, SO2) to the lava during cooling and that the transfer of oxygen also controls the fugacities of several minor and trace species (H2, CO, H2S, S2, Cl2, F2), in addition to O2 during cooling. Gas/lava exchanges of other components are apparently insignificant and exert little influence, compared to oxygen exchange, during cooling. Oxygen transfer during cooling is variable, presumably reflecting short-term fluctuations in gas flow rates. Higher flow rates restrict the time available for gas/lava oxygen transfer and result in gases with higher equilibrium temperatures. Lower flow rates favor fO2-constrained equilibration by oxygen transfer down to lower temperatures. Thus, the chemical equilibrium preserved in these gases is a heterogeneous equilibrium constrained by oxygen fugacity, and the equilibrium temperatures implied by the compositions of the gases reflect the temperatures at which gas/lava oxygen exchange ceased. This conclusion

Separation of gases through gas enrichment membrane composites

DOEpatents

Swedo, R.J.; Kurek, P.R.

1988-07-19

Thin film composite membranes having as a permselective layer a film of a homopolymer of certain vinyl alkyl ethers are useful in the separation of various gases. Such homopolymers have a molecular weight of greater than 30,000 and the alkyl group of the vinyl alkyl monomer has from 4 to 20 carbon atoms with branching within the alkyl moiety at least at the carbon atom bonded to the ether oxygen or at the next adjacent carbon atom. These membranes show excellent hydrolytic stability, especially in the presence of acidic or basic gaseous components.

Separation of gases through gas enrichment membrane composites

DOEpatents

Swedo, Raymond J.; Kurek, Paul R.

1988-01-01

Thin film composite membranes having as a permselective layer a film of a homopolymer of certain vinyl alkyl ethers are useful in the separation of various gases. Such homopolymers have a molecular weight of greater than 30,000 and the alkyl group of the vinyl alkyl monomer has from 4 to 20 carbon atoms with branching within the alkyl moiety at least at the carbon atom bonded to the ether oxygen or at the next adjacent carbon atom. These membranes show excellent hydrolytic stability, especially in the presence of acidic or basic gaseous components.

Electron microscopy of carbonaceous matter in Allende acid residues

NASA Technical Reports Server (NTRS)

Lumpkin, G. R.

1982-01-01

On the basis of characteristic diffuse ring diffraction patterns, much of the carbonaceous matter in a large suite of Allende acid residues has been identified as a variety of turbostratic carbon. Crystallites of this phase contain randomly stacked sp(2) hybridized carbon layers and diffraction patterns resemble those from carbon black and glassy carbon. Carbynes are probably absent, and are certainly restricted to less than 0.5% of these acid residues. The work of Ott et al. (1981) provides a basis for the possibility that turbostratic carbon is a carrier of noble gases, but an additional component - amorphous carbon - may be necessary to explain the high release temperatures of noble gases as well as the glassy character of many of the carbonaceous particles. Carbynes are considered to be questionable as important carriers of noble gases in the Allende acid residues.

A Portable FTIR Analyser for Field Measurements of Trace Gases and their Isotopologues: CO2, CH4, N2O, CO, del13C in CO2 and delD in water vapour

NASA Astrophysics Data System (ADS)

Griffith, D. W.; Bryant, G. R.; Deutscher, N. M.; Wilson, S. R.; Kettlewell, G.; Riggenbach, M.

2007-12-01

We describe a portable Fourier Transform InfraRed (FTIR) analyser capable of simultaneous high precision analysis of CO2, CH4, N2O and CO in air, as well as δ13C in CO2 and δD in water vapour. The instrument is based on a commercial 1 cm-1 resolution FTIR spectrometer fitted with a mid-IR globar source, 26 m multipass White cell and thermoelectrically-cooled MCT detector operating between 2000 and 7500 cm-1. Air is passed through the cell and analysed in real time without any pre-treatment except for (optional) drying. An inlet selection manifold allows automated sequential analysis of samples from one or more inlet lines, with typical measurement times of 1-10 minutes per sample. The spectrometer, inlet sampling sequence, real-time quantitative spectrum analysis, data logging and display are all under the control of a single program running on a laptop PC, and can be left unattended for continuous measurements over periods of weeks to months. Selected spectral regions of typically 100-200 cm-1 width are analysed by a least squares fitting technique to retrieve concentrations of trace gases, 13CO2 and HDO. Typical precision is better than 0.1% without the need for calibration gases. Accuracy is similar if measurements are referenced to calibration standard gases. δ13C precision is typically around 0.1‰, and for δD it is 1‰. Applications of the analyser include clean and polluted air monitoring, tower-based flux measurements such as flux gradient or integrated horizontal flux measurements, automated soil chambers, and field-based measurements of isotopic fractionation in soil-plant-atmosphere systems. The simultaneous multi-component advantages can be exploited in tracer-type emission measurements, for example of CH4 from livestock using a co-released tracer gas and downwind measurement. We have also developed an open path variant especially suited to tracer release studies and measurements of NH3 emissions from agricultural sources. An illustrative

Biomass burning emissions of trace gases and particles in marine air at Cape Grim, Tasmania, 41° S

NASA Astrophysics Data System (ADS)

Lawson, S. J.; Keywood, M. D.; Galbally, I. E.; Gras, J. L.; Cainey, J. M.; Cope, M. E.; Krummel, P. B.; Fraser, P. J.; Steele, L. P.; Bentley, S. T.; Meyer, C. P.; Ristovski, Z.; Goldstein, A. H.

2015-07-01

with a large CO enhancement, an increase of the NMOC / CO emission ratio (ER) by a factor of 2-4 and a halving of the BC / CO ratio. Rainfall on Robbins Island was observed by radar during this period which likely resulted in a lower fire combustion efficiency, and higher emission of compounds associated with smouldering. This highlights the importance of relatively minor meterological events on BB emissions. Emission factors (EF) were derived for a range of trace gases, some never before reported for Australian conditions, (including hydrogen, phenol and toluene) using a calculated ER to CO and a published CO EF. The EF derived for most species are comparable to other temperate Australian studies but lower than Northern Hemisphere temperate studies. This work demonstrates the substantial impact that BB plumes have on the composition of marine air, and the significant changes that can occur as the plume is diluted and interacts with other emission sources. We also provide new trace gas and particle EF for temperate southern Australia.

Plutonium oxalate precipitation for trace elemental determination in plutonium materials

DOE PAGES

Xu, Ning; Gallimore, David; Lujan, Elmer; ...

2015-05-26

In this study, an analytical chemistry method has been developed that removes the plutonium (Pu) matrix from the dissolved Pu metal or oxide solution prior to the determination of trace impurities that are present in the metal or oxide. In this study, a Pu oxalate approach was employed to separate Pu from trace impurities. After Pu(III) was precipitated with oxalic acid and separated by centrifugation, trace elemental constituents in the supernatant were analyzed by inductively coupled plasma-optical emission spectroscopy with minimized spectral interferences from the sample matrix.

The Changing Atmosphere.

ERIC Educational Resources Information Center

Graedel, Thomas E.; Crutzen, Paul J.

1989-01-01

Discusses air pollution occurring due to human activity. Describes which human activities generate which emissions, including acid rain, smog, ozone depletion, and change of trace gases. Suggests global effort to solve the earth's environmental problems. (YP)

Release of radiogenic noble gases as a new signal of rock deformation

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

Bauer, Stephen J.; Gardner, W. Payton; Lee, Hyunwoo

In this paper we investigate the release of radiogenic noble gas isotopes during mechanical deformation. We developed an analytical system for dynamic mass spectrometry of noble gas composition and helium release rate of gas produced during mechanical deformation of rocks. Our results indicate that rocks release accumulated radiogenic helium and argon from mineral grains as they undergo deformation. We found that the release of accumulated 4He and 40Ar from rocks follows a reproducible pattern and can provide insight into the deformation process. Increased gas release can be observed before dilation, and macroscopic failure is observed during high-pressure triaxial rock deformationmore » experiments. Accumulated radiogenic noble gases can be released due to fracturing of mineral grains during small-scale strain in Earth materials. Helium and argon are highly mobile, conservative species and could be used to provide information on changes in the state of stress and strain in Earth materials, and as an early warning signal of macroscopic failure. These results pave the way for the use of noble gases to trace and monitor rock deformation for earthquake prediction and a variety of other subsurface engineering projects.« less

Release of radiogenic noble gases as a new signal of rock deformation

DOE PAGES

Bauer, Stephen J.; Gardner, W. Payton; Lee, Hyunwoo

2016-10-09

In this paper we investigate the release of radiogenic noble gas isotopes during mechanical deformation. We developed an analytical system for dynamic mass spectrometry of noble gas composition and helium release rate of gas produced during mechanical deformation of rocks. Our results indicate that rocks release accumulated radiogenic helium and argon from mineral grains as they undergo deformation. We found that the release of accumulated 4He and 40Ar from rocks follows a reproducible pattern and can provide insight into the deformation process. Increased gas release can be observed before dilation, and macroscopic failure is observed during high-pressure triaxial rock deformationmore » experiments. Accumulated radiogenic noble gases can be released due to fracturing of mineral grains during small-scale strain in Earth materials. Helium and argon are highly mobile, conservative species and could be used to provide information on changes in the state of stress and strain in Earth materials, and as an early warning signal of macroscopic failure. These results pave the way for the use of noble gases to trace and monitor rock deformation for earthquake prediction and a variety of other subsurface engineering projects.« less

Control of Effluent Gases from Solid Waste Processing using Impregnated Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Li, Jing; Fisher, John; Wignarajah, Kanapathipillai

2005-01-01

One of the major problems associated with solid waste processing technologies is effluent contaminants that are released in gaseous forms from the processes. This is a concern in both biological as well as physicochemical solid waste processing. Carbon dioxide (CO2), the major gas released, does not present a serious problem and there are currently in place a number of flight-qualified technologies for CO2 removal. However, a number of other gases, in particular NOx, SO2, NH3, and various hydrocarbons (e.g. CH4) do present health hazards to the crew members in space habitats. In the present configuration of solid waste processing in the International Space Station (ISS), some of these gases are removed by the Trace Contaminant Control System (TCCS), demands a major resupply. Reduction of the resupply can be effective by using catalyst impregnated carbon nanotubes. For example, NO decomposition to N2 and O2 is thermodynamically favored. Data showing decomposition of NO on metal impregnated carbon nanotubes is presented. Comparisons are made of the existing TCCS systems with the carbon nanotube based technology for removing NOx based on mass/energy penalties.

Distribution of trace gases and aerosols in the Siberian air shed during wildfires of summer 2012

NASA Astrophysics Data System (ADS)

Belan, Boris D.; Paris, Jean-Daiel; Nedelec, Philippe; Antokhin, Pavel N.; Arshinova, Victoriya; Arshinov, Mikhail Yu.; Belan, Sergey B.; Davydov, Denis K.; Ivlev, Georgii A.; Fofonov, Alexandre V.; Kozlov, Artem V.; Rasskazchikova, Tatyana M.; Savkin, Denis E.; Simonenkov, Denis V.; Sklyadneva, Tatyana K.; Tolmachev, Gennadii N.

2017-04-01

During the last two decades, three strong biomass burning events have been observed in Russia: two of them in 2002 and 2010 in the European part of Russia, and another one in 2012 in West and East Siberia. In this paper we present results of the extensive airborne study of the vertical distribution of trace gases and aerosols carried out during strong wildfire event happened in summer 2012 in Siberia. For this purpose, the Optik TU-134 aircraft laboratory was used as a research platform. A large-scale airborne campaign has been undertaken along the route Novosibirsk-Mirny-Yakutsk-Bratsk-Novosibirsk on 31st of July and 1st of August, 2012. Flight pattern consisted of a number of ascents and descents between close to the ground and 8 km altitude that enabled 20 vertical profiles to be obtained. Campaign was conducted under the weather conditions of low-gradient baric field that determined the low speed transport of air masses, as well as the accumulation of biomass burning emissions in the region under study. Highest concentrations of CO2, CH4 and CO over wildfire spots reached 432 ppm, 2367 ppb, and 4036 ppb, correspondingly. If we exclude from the analysis the data obtained when crossing smoke plumes, we can find a difference between background concentrations measured in the atmosphere over regions affected by biomass burning and clean areas. Enhancement of CO2 over the wildfire areas changed with altitude. On average, it was 10.5 ppm in the atmospheric boundary layer (ABL) and 5-6 ppm in the free troposphere. Maximum CO2 enhancements reached 27 ppm and 24 ppm, correspondingly. The averaged CH4 enhancement varied from 75 ppb in the boundary layer to 30 ppb in the upper troposphere, and a little bit lower than 30 ppb in the middle troposphere. Maximum CH4 enhancements reached 202 ppb, 108 ppb, and 50-60 ppb, correspondingly. The averaged and maximum enhancements of CO differed by an order of magnitude. Thus, in the ABL the maximum difference in concentration between

Inert gases in Sea of Fertility regolith

NASA Technical Reports Server (NTRS)

Vinogradov, A. P.; Zadorozhnyy, I. K.

1974-01-01

The content and isotopic composition were studied of inert gases -- He, Ne, Ar, Kr, and Xe -- in samples of lunar regolith returned by the Luna 16 automatic station. The samples were taken from depths of about 12 and 30 cm. The high concentrations of inert gases exceed by several orders their concentrations observed in ordinary stony meteorites. The gases in lunar regolith were a complex mixture of gases of different origins: Solar, cosmogenic, radiogenic, and so on. Solar wind gases predominated, distributed in the thin surficial layer of the regolith grains. The concentrations of these gases in the surficial layer is several cubic centimeters per gram. The isotopic composition of the inert gases of solar origin approaches their composition measured in gas-rich meteorites.

Phase Partitioning of Soluble Trace Gases with Size-Resolved Aerosols during the Nitrogen, Aerosol Composition, and Halogens on a Tall Tower (NACHTT) Campaign

NASA Astrophysics Data System (ADS)

Young, A.; Keene, W. C.; Pszenny, A.; Sander, R.; Maben, J. R.; Warrick-Wriston, C.; Bearekman, R.

2011-12-01

During February and March 2011, size-resolved and bulk aerosol were sampled at 22 m above the surface over nominal 12-hour (daytime and nighttime) intervals from the Boulder Atmospheric Observatory tower (40.05 N, 105.01 W, 1584-m elevation). Samples were analyzed for major organic and inorganic ionic constituents by high performance ion chromatography (IC). Soluble trace gases (HCl, HNO3, NH3, HCOOH, and CH3COOH) were sampled in parallel over 2-hour intervals with tandem mist chambers and analyzed on site by IC. NH4+, NO3-, and SO42- were the major ionic components of aerosols (median values of 57.7, 34.5, and 7.3 nmol m-3 at STP, respectively, N = 45) with 86%, 82%, and 82%, respectively, associated with sub-μm size fractions. Cl- and Na+ were present at significant concentrations (median values of 6.8 and 6.6 nmol m-3, respectively) but were associated primarily with super-μm size fractions (75% and 78%, respectively). Median values (and ranges) for HCl, HNO3, and NH3 were 21 (<20-1257), 120 (<45-1638), and 5259 (<1432-48,583) pptv, respectively. Liquid water contents of size-resolved aerosols and activity coefficients for major ionic constituents were calculated with the Extended Aerosol Inorganic Model II and IV (E-AIM) based on the measured aerosol composition, RH, temperature, and pressure. Size-resolved aerosol pHs were inferred from the measured phase partitioning of HCl, HNO3, and NH3. Major controls of phase partitioning and associated chemical dynamics will be presented.

Research on the 2nd generation biofuel BIOXDIESEL in aspects of emission of toxic substances in exhaust gases

NASA Astrophysics Data System (ADS)

Struś, M. S.; Poprawski, W.; Rewolte, M.

2016-09-01

This paper presents results of research of Diesel engines emission of toxic substances in exhaust gases fuelled with a second generation biofuel BIOXDIESEL, which is a blend of Fatty Acid Ethyl Esters obtained from waste resources such waste vegetable and animal fats, bioethanol and standard Diesel fuel. Presented results are very promising, showing that the emission of toxic substances in exhaust gases are significantly reduced when fuelling with BIOXDIESEL fuel in comparison with standard Diesel fuel.

study on trace contaminants control assembly for sealed environment chamber

NASA Astrophysics Data System (ADS)

Pang, L. P.; Wang, J.; Liu, L. K.; Liu, H.

The biological and Physicochemical P C life support technologies are all important parts to establish a human Closed Ecological Life Support System CELSS for long-duration mission The latter has the advantages of lower power consumption lower mass and higher efficiency therefore researchers often incorporate the use of biological systems with P C life support technologies to continuously recycle air water and part of the solid waste stream generated such as the Russian BLSS and the NASA-sponsored Lunar-Mars Life Support Test Project LMLSTP In short these tests were very successful in integrating biological and P C life support technologies for long-duration life support Therefore we should use a combination of integrated biological with P C life support technologies in a human CELSS Human construction materials plants animals and soils release much trace toxic gases in a CELSS and they will inhibit plant growth and badly affect human health when their concentrations rise over their threshold levels The effect of biological trace contaminant control technologies is slower especially for a human sealed chamber because human produce much more methane and other contaminants A regenerative Trace Contaminant Control Subsystem TCCS with P C technology is a more important part in this case to control quickly the airborne contaminants levels and assure human in good condition in a sealed chamber This paper describes a trace contaminant control test facility incorporated a 8 m3 sealed environment chamber a regenerative TCCS with P C

Elimination of cadmium trace contaminations from drinking water.

PubMed

Zhao, Xuan; Höll, Wolfgang H; Yun, Guichun

2002-02-01

Raw waters polluted with trace heavy metals present serious problems to the part of the Chinese water supply. One of the important contaminants is cadmium. Removal of trace amounts of heavy metals can be achieved by means of selective sorption processes. One of the possibilities is the application of weak base anion exchangers. LEWIS-base/acid interactions lead to an exclusive sorption of heavy metal cations and an equivalent amount of anions of strong acids. The respective elimination of cadmium from pure solutions and spiked natural water and the regeneration of the exhausted exchanger has been investigated. The results demonstrate a very efficient elimination. The standards for drinking water are met for a very large relative volume of treated water. In addition, even a considerable share of dissolved organic matter is adsorbed. Regeneration requires a first step with sulfuric acid to remove the metals and a second one with sodium hydroxide to neutralize the exchanger and to displace the DOC adsorbed. The heavy metals can be concentrated in a small volume which facilitates the discharge of the waste.

Comparison of MAX-DOAS profiling algorithms during CINDI-2 - Part 2: trace gases

NASA Astrophysics Data System (ADS)

Hendrick, Francois; Friess, Udo; Tirpitz, Lukas; Apituley, Arnoud; Van Roozendael, Michel; Kreher, Karin; Richter, Andreas; Wagner, Thomas

2017-04-01

The second Cabauw Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI-2) took place at the Cabauw Experimental Site for Atmospheric Research (CESAR; Utrecht area, The Netherlands) from 25 August until 7 October 2016. CINDI-2 was aiming at assessing the consistency of MAX-DOAS slant column density measurements of tropospheric species (NO2, HCHO, O3, and O4) relevant for the validation of future ESA atmospheric Sentinel missions, through coordinated operation of a large number of DOAS and MAXDOAS instruments from all over the world. An important objective of the campaign was to study the relationship between remote-sensing column and profile measurements of the above species and collocated reference ancillary observations. For this purpose, the CINDI-2 Profiling Task Team (CPTT) was created, involving 22 groups performing aerosol and trace gas vertical profile inversion using dedicated MAX-DOAS profiling algorithms, as well as the teams responsible for ancillary profile and surface concentration measurements (NO2 analysers, NO2 sondes, NO2 and Raman LIDARs, CAPS, Long-Path DOAS, sunphotometer, nephelometer, etc). The main purpose of the CPTT is to assess the consistency of the different profiling tools for retrieving aerosol extinction and trace gas vertical profiles through comparison exercises using commonly defined settings and to validate the retrievals with correlative observations. In this presentation, we give an overview of the MAX-DOAS vertical profile comparison results, focusing on NO2 and HCHO, the aerosol retrievals being presented in a companion abstract led by U. Frieß. The performance of the different algorithms is investigated with respect to the various sky and weather conditions and aerosol loadings encountered during the campaign. The consistency between optimal-estimation-based and parameterized profiling tools is also evaluated for these different conditions, together with the level of agreement with available NO2 and

Chapter 16Tracing Nitrogen Sources and Cycling in Catchments

USGS Publications Warehouse

Kendall, Carol

1998-01-01

This chapter focuses on the uses of isotopes to understand water chemistry.I Isotopic compositions generally cannot be interpreted successfully in the absence of other chemical and hydrologic data. The chapter focusses on uses of isotopes in tracing sources and cycling of nitrogen in the water-component of forested catchment, and on dissolved nitrate in shallow waters, nutrient uptake studies in agricultural areas, large-scale tracer experiments, groundwater contamination studies, food-web investigations, and uses of compound-specific stable isotope techniques. Shallow waters moving along a flowpath through a relatively uniform material and reacting with minerals probably do not achieve equilibrium but gradually approach some steady-state composition. The chapter also discusses the use of isotopic techniques to assess impacts of changes in land-management practices and land use on water quality. The analysis of individual molecular components for isotopic composition has much potential as a method for tracing the source, biogeochemistry, and degradation of organic liquids and gases because different materials have characteristic isotope spectrums or biomarkers.

Direct analysis of ultra-trace semiconductor gas by inductively coupled plasma mass spectrometry coupled with gas to particle conversion-gas exchange technique.

PubMed

Ohata, Masaki; Sakurai, Hiromu; Nishiguchi, Kohei; Utani, Keisuke; Günther, Detlef

2015-09-03

An inductively coupled plasma mass spectrometry (ICPMS) coupled with gas to particle conversion-gas exchange technique was applied to the direct analysis of ultra-trace semiconductor gas in ambient air. The ultra-trace semiconductor gases such as arsine (AsH3) and phosphine (PH3) were converted to particles by reaction with ozone (O3) and ammonia (NH3) gases within a gas to particle conversion device (GPD). The converted particles were directly introduced and measured by ICPMS through a gas exchange device (GED), which could penetrate the particles as well as exchange to Ar from either non-reacted gases such as an air or remaining gases of O3 and NH3. The particle size distribution of converted particles was measured by scanning mobility particle sizer (SMPS) and the results supported the elucidation of particle agglomeration between the particle converted from semiconductor gas and the particle of ammonium nitrate (NH4NO3) which was produced as major particle in GPD. Stable time-resolved signals from AsH3 and PH3 in air were obtained by GPD-GED-ICPMS with continuous gas introduction; however, the slightly larger fluctuation, which could be due to the ionization fluctuation of particles in ICP, was observed compared to that of metal carbonyl gas in Ar introduced directly into ICPMS. The linear regression lines were obtained and the limits of detection (LODs) of 1.5 pL L(-1) and 2.4 nL L(-1) for AsH3 and PH3, respectively, were estimated. Since these LODs revealed sufficiently lower values than the measurement concentrations required from semiconductor industry such as 0.5 nL L(-1) and 30 nL L(-1) for AsH3 and PH3, respectively, the GPD-GED-ICPMS could be useful for direct and high sensitive analysis of ultra-trace semiconductor gas in air. Copyright © 2015 Elsevier B.V. All rights reserved.

Characterizing spatial and temporal variability of dissolved gases in aquatic environments with in situ mass spectrometry.

PubMed

Camilli, Richard; Duryea, Anthony N

2009-07-01

The TETHYS mass spectrometer is intended for long-term in situ observation of dissolved gases and volatile organic compounds in aquatic environments. Its design maintains excellent low mass range sensitivity and stability during long-term operations, enabling characterization of low-frequency variability in many trace dissolved gases. Results are presented from laboratory trials and a 300-h in situ trial in a shallow marine embayment in Massachusetts, U.S.A. This time series consists of over 15000 sample measurements and represents the longest continuous record made by an in situ mass spectrometer in an aquatic environment. These measurements possess sufficient sampling density and duration to apply frequency analysis techniques for study of temporal variability in dissolved gases. Results reveal correlations with specific environmental periodicities. Numerical methods are presented for converting mass spectrometer ion peak ratios to absolute-scale dissolved gas concentrations across wide temperature regimes irrespective of ambient pressure, during vertical water column profiles in a hypoxic deep marine basin off the coast of California, U.S.A. Dissolved oxygen concentration values obtained with the TETHYS instrument indicate close correlation with polarographic oxygen sensor data across the entire depth range. These methods and technology enable observation of aquatic environmental chemical distributions and dynamics at appropriate scales of resolution.

Exposure assessment of oxidant gases and acidic aerosols

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

Lioy, P.J.

1989-01-01

Clearly the presence of high ozone and acidic species in North America is primarily dependent upon photochemical air pollution. Evidence shows, however, that high acid exposures may occur in specific types of areas of high sulfur fuel use during the winter. At the present time, our concerns about exposure to local populations and regional populations should be directed primarily toward the outdoor activity patterns of individuals in the summer, and how those activity patterns relate to the location, duration, and concentrations of ozone and acid aerosol in photochemical air pollution episodes. Lioy Dyba and Mage et al have examined themore » activity patterns of children in summer camps. Because they spend more time outside than the normal population, these children form an important group of exercising individuals subject to photochemical pollution exposures. The dose of ozone inhaled by the children in the two camps was within 50% and 25% of the dose inhaled by adults in controlled clinical situations that produced clinically significant decrements in pulmonary function and increased the symptoms after 6.6 hr exposure in a given day. The chamber studies have used only ozone, whereas in the environment this effect may be enhanced by the presence of a complex mixture. The work of Lioy et al in Mendham, New Jersey found that hydrogen ion seemed to play a role in the inability of the children to return immediately to their normal peak expiratory flow rate after exposure. The camp health study conducted in Dunsville, Ontario suggested that children participating in a summer camp where moderate levels of ozone (100 ppb) but high levels of acid (46 micrograms/m3) occurred during an episode had a similar response. Thus, for children or exercising adults who are outdoors for at least one hour or more during a given day, the presence and persistence of oxidants in the environment are of particular concern. 63 references.« less

Long open-path measurements of greenhouse gases in air using near-infrared Fourier transform spectroscopy

NASA Astrophysics Data System (ADS)

Griffith, David W. T.; Pöhler, Denis; Schmitt, Stefan; Hammer, Samuel; Vardag, Sanam N.; Platt, Ulrich

2018-03-01

In complex and urban environments, atmospheric trace gas composition is highly variable in time and space. Point measurement techniques for trace gases with in situ instruments are well established and accurate, but do not provide spatial averaging to compare against developing high-resolution atmospheric models of composition and meteorology with resolutions of the order of a kilometre. Open-path measurement techniques provide path average concentrations and spatial averaging which, if sufficiently accurate, may be better suited to assessment and interpretation with such models. Open-path Fourier transform spectroscopy (FTS) in the mid-infrared region, and differential optical absorption spectroscopy (DOAS) in the UV and visible, have been used for many years for open-path spectroscopic measurements of selected species in both clean air and in polluted environments. Near infrared instrumentation allows measurements over longer paths than mid-infrared FTS for species such as greenhouse gases which are not easily accessible to DOAS.In this pilot study we present the first open-path near-infrared (4000-10 000 cm-1, 1.0-2.5 µm) FTS measurements of CO2, CH4, O2, H2O and HDO over a 1.5 km path in urban Heidelberg, Germany. We describe the construction of the open-path FTS system, the analysis of the collected spectra, several measures of precision and accuracy of the measurements, and the results a four-month trial measurement period in July-November 2014. The open-path measurements are compared to calibrated in situ measurements made at one end of the open path. We observe significant differences of the order of a few ppm for CO2 and a few tens of ppb for CH4 between the open-path and point measurements which are 2 to 4 times the measurement repeatability, but we cannot unequivocally assign the differences to specific local sources or sinks. We conclude that open-path FTS may provide a valuable new tool for investigations of atmospheric trace gas composition in

46 CFR 147.60 - Compressed gases.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Compressed gases. 147.60 Section 147.60 Shipping COAST... Other Special Requirements for Particular Materials § 147.60 Compressed gases. (a) Cylinder requirements. Cylinders used for containing hazardous ships' stores that are compressed gases must be— (1) Authorized for...

Trace analysis of muramic acid in indoor air using an automated derivatization instrument and GC-MS(2) or GC-MS(3).

PubMed

Harley, William M; Kozar, Michael P; Fox, Alvin

2002-09-01

An automated derivatization instrument has been developed for the preparation of alditol acetates from bacterial hydrolysates for analysis by gas chromatography-mass spectrometry (GC-MS). The current report demonstrates the utility of the automated instrument for the more demanding task of trace analysis of muramic acid (Mur) in airborne dust using gas chromatography-tandem mass spectrometry (GC-MS(2)). Conditions for efficient derivatization of Mur, vital for trace analysis, are rigorous including lactam and imido group formation under anhydrous conditions. Furthermore, as the detection limit is lowered, possible contamination or carry-over of samples becomes an increasingly greater consideration and must not occur. The instrument meets these criteria and was successfully used for assaying the levels of Mur in laboratory air, which were found to be much lower than in the previous studies of heavily occupied schools and agricultural environments. The potential for GC-MS(3) in further lowering the detection limit was also demonstrated.

Wet scavenging of soluble gases in DC3 deep convective storms using WRF-Chem simulations and aircraft observations: DEEP CONVECTIVE WET SCAVENGING OF GASES

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

Bela, Megan M.; Barth, Mary C.; Toon, Owen B.

We examine wet scavenging of soluble trace gases in storms observed during the Deep Convective Clouds and Chemistry (DC3) field campaign. We conduct high-resolution simulations with the Weather Research and Forecasting model with Chemistry (WRF-Chem) of a severe storm in Oklahoma. The model represents well the storm location, size, and structure as compared with Next Generation Weather Radar reflectivity, and simulated CO transport is consistent with aircraft observations. Scavenging efficiencies (SEs) between inflow and outflow of soluble species are calculated from aircraft measurements and model simulations. Using a simple wet scavenging scheme, we simulate the SE of each soluble speciesmore » within the error bars of the observations. The simulated SEs of all species except nitric acid (HNO3) are highly sensitive to the values specified for the fractions retained in ice when cloud water freezes. To reproduce the observations, we must assume zero ice retention for formaldehyde (CH2O) and hydrogen peroxide (H2O2) and complete retention for methyl hydrogen peroxide (CH3OOH) and sulfur dioxide (SO2), likely to compensate for the lack of aqueous chemistry in the model. We then compare scavenging efficiencies among storms that formed in Alabama and northeast Colorado and the Oklahoma storm. Significant differences in SEs are seen among storms and species. More scavenging of HNO3 and less removal of CH3OOH are seen in storms with higher maximum flash rates, an indication of more graupel mass. Graupel is associated with mixed-phase scavenging and lightning production of nitrogen oxides (NOx ), processes that may explain the observed differences in HNO3 and CH3OOH scavenging.« less

Closed System Step Etching of CI chondrite Ivuna reveals primordial noble gases in the HF-solubles

NASA Astrophysics Data System (ADS)

Riebe, My E. I.; Busemann, Henner; Wieler, Rainer; Maden, Colin

2017-05-01

We analyzed all the noble gases in HF-soluble phases in the CI chondrite Ivuna by in-vacuum gas release using the "Closed System Step Etching" (CSSE) technique, which allows for direct noble gas measurements of acid-soluble phases. The main motivation was to investigate if there are primordial noble gases in HF-soluble phases in Ivuna, something that has not been done before in CI chondrites, as most primordial noble gases are known to reside in HF-resistant phases. The first steps under mild etching released He, Ne, and Ar with solar-like elemental and isotopic compositions, confirming that Ivuna contains implanted solar wind (SW) noble gases acquired in the parent body regolith. The SW component released in some etch steps was elementally unfractionated. This is unusual as trapped SW noble gases are elementally fractionated in most meteoritic material. In the intermediate etch steps under slightly harsher etching, cosmogenic noble gases were more prominent than SW noble gases. The HF-soluble portion of Ivuna contained primordial Ne and Xe, that was most visible in the last etch steps after all cosmogenic and most SW gases had been released. The primordial Ne and Xe in the HF-solubles have isotopic and elemental ratios readily explained as a mixture of the two most abundant primordial noble gas components in Ivuna bulk samples: HL and Q. Only small fractions of the total HL and Q in Ivuna were released during CSSE analysis; ∼3% of 20NeHL and ∼4% of 132XeQ. HL is known to reside in nanodiamond-rich separates and Q-gases are most likely carried by a carbonaceous phase known as phase Q. Q-gases were likely released from an HF-soluble portion of phase Q. However, nanodiamonds might not be the source of the HL-gases released upon etching, since nanodiamond-rich separates are very HF-resistant and the less tightly bound nanodiamond component P3 was not detected.

Concentrations of Reactive Trace Gases In The Interstitial Air of Surface Snow

NASA Astrophysics Data System (ADS)

Jacobi, H.-W.; Honrath, R. E.; Peterson, M. C.; Lu, Y.; Dibb, J. E.; Arsenault, M. A.; Swanson, A. L.; Blake, N. J.; Bales, R. C.; Schrems, O.

Several measurements at Arctic and Antarctic sites have demonstrated that unexpected photochemical reactions occur in irradiated surface snow influencing the composi- tion of the boundary layer over snow-covered areas. The results of these reactions are probably most obvious in the interstitial air of the surface snow since it constitutes the interface between the surface snow and the boundary layer. Therefore, measurements of concentrations of nitrogen oxide and dioxide, nitrous acid, formaldehyde, hydro- gen peroxide, formic acid, acetic acid, and other organic compounds were performed in the interstitial air of the surface snow of the Greenland ice sheet. Concentrations were measured at variable depths between - 10 cm and - 50 cm during the summer field season in 2000 at the Summit Environmental Observatory. At shallow depths, the system NO-NO2-O3 exhibits large deviations from the calculated photostationary state. Using steady-state analyses applied to OH-HO2-CH3O2 cycling indicated the presence of high concentrations of OH and peroxy radicals in the firn air. Maximum concentrations calculated for a depth of - 10 cm are in the order of 6 105 molecules cm-3 and 1.4 * 107 molecules cm-3 for OH and HO2, respectively, although radia- tion levels at - 10 cm are reduced by approximately 50 % compared to levels above the snow surface. By far the most important OH source is the photolysis of HONO while the photolysis of ozone contributes less than 2 % to the overall production of OH in the firn air.

From biota to chemistry and climate: towards a comprehensive description of trace gas exchange between the biosphere and atmosphere

NASA Astrophysics Data System (ADS)

Arneth, A.; Sitch, S.; Bondeau, A.; Butterbach-Bahl, K.; Foster, P.; Gedney, N.; de Noblet-Ducoudré, N.; Prentice, I. C.; Sanderson, M.; Thonicke, K.; Wania, R.; Zaehle, S.

2010-01-01

Exchange of non-CO2 trace gases between the land surface and the atmosphere plays an important role in atmospheric chemistry and climate. Recent studies have highlighted its importance for interpretation of glacial-interglacial ice-core records, the simulation of the pre-industrial and present atmosphere, and the potential for large climate-chemistry and climate-aerosol feedbacks in the coming century. However, spatial and temporal variations in trace gas emissions and the magnitude of future feedbacks are a major source of uncertainty in atmospheric chemistry, air quality and climate science. To reduce such uncertainties Dynamic Global Vegetation Models (DGVMs) are currently being expanded to mechanistically represent processes relevant to non-CO2 trace gas exchange between land biota and the atmosphere. In this paper we present a review of important non-CO2 trace gas emissions, the state-of-the-art in DGVM modelling of processes regulating these emissions, identify key uncertainties for global scale model applications, and discuss a methodology for model integration and evaluation.

From biota to chemistry and climate: towards a comprehensive description of trace gas exchange between the biosphere and atmosphere

NASA Astrophysics Data System (ADS)

Arneth, A.; Sitch, S.; Bondeau, A.; Butterbach-Bahl, K.; Foster, P.; Gedney, N.; de Noblet-Ducoudré, N.; Prentice, I. C.; Sanderson, M.; Thonicke, K.; Wania, R.; Zaehle, S.

2009-07-01

Exchange of non-CO2 trace gases between the land surface and the atmosphere plays an important role in atmospheric chemistry and climate. Recent studies have highlighted its importance for interpretation of glacial-interglacial ice-core records, the simulation of the pre-industrial and present atmosphere, and the potential for large climate-chemistry and climate-aerosol feedbacks in the coming century. However, spatial and temporal variations in trace gas emissions and the magnitude of future feedbacks are a major source of uncertainty in atmospheric chemistry, air quality and climate science. To reduce such uncertainties Dynamic Global Vegetation Models (DGVMs) are currently being expanded to mechanistically represent processes relevant to non-CO2 trace gas exchange between land biota and the atmosphere. In this paper we present a review of important non-CO2 trace gas emissions, the state-of-the-art in DGVM modelling of processes regulating these emissions, identify key uncertainties for global scale model applications, and discuss a methodology for model integration and evaluation.

Emissions of biogenic sulfur gases from northern bogs and fens

NASA Technical Reports Server (NTRS)

Demello, William Zamboni; Hines, Mark E.; Bayley, Suzanne E.

1992-01-01

Sulfur gases are important components of the global cycle of S. They contribute to the acidity of precipitation and they influence global radiation balance and climate. The role of terrestrial sources of biogenic S and their effect on atmospheric chemistry remain as major unanswered questions in our understanding of the natural S cycle. The role of northern wetlands as sources and sinks of gaseous S by measuring rates of S gas exchange as a function of season, hydrologic conditions, and gradients in tropic status was investigated. Experiments were conducted in wetlands in New Hampshire, particularly a poor fen, and in Mire 239, a poor fen at the Experimental Lakes Area (ELA) in Ontario. Emissions were determined using Teflon enclosures, gas cryotrapping methods and gas chromatography (GC) with flame photometric detection. Dynamic (sweep flow) and static enclosures were employed which yielded similar results. Dissolved S gases and methane were determined by gas stripping followed by GC.

Cloud draft structure and trace gas transport

NASA Technical Reports Server (NTRS)

Scala, John R.; Tao, Wei-Kuo; Thompson, Anne M.; Simpson, Joanne; Garstang, Michael; Pickering, Kenneth E.; Browell, Edward V.; Sachse, Glen W.; Gregory, Gerald L.; Torres, Arnold L.

1990-01-01

During the second Amazon Boundary Layer Experiment (ABLE 2B), meteorological observations, chemical measurements, and model simulations are utilized in order to interpret convective cloud draft structure and to analyze its role in transport and vertical distribution of trace gases. One-dimensional photochemical model results suggest that the observed poststorm changes in ozone concentration can be attributed to convective transports rather than photochemical production and the results of a two-dimensional time-dependent cloud model simulation are presented for the May 6, 1987 squall system. The mesoscale convective system exhibited evidence of significant midlevel detrainment in addition to transports to anvil heights. Chemical measurements of O3 and CO obtained in the convective environment are used to predict photochemical production within the troposphere and to corroborate the cloud model results.

Amplification of trace amounts of nucleic acids

DOEpatents

Church, George M [Brookline, MA; Zhang, Kun [Brighton, MA

2008-06-17

Methods of reducing background during amplification of small amounts of nucleic acids employ careful analysis of sources of low level contamination. Ultraviolet light can be used to reduce nucleic acid contaminants in reagents and equipment. "Primer-dimer" background can be reduced by judicious design of primers. We have shown clean signal-to-noise with as little as starting material as one single human cell (.about.6 picogram), E. coli cell (.about.5 femtogram) or Prochlorococcus cell (.about.3 femtogram).

Method of concurrently filtering particles and collecting gases

DOEpatents

Mitchell, Mark A; Meike, Annemarie; Anderson, Brian L

2015-04-28

A system for concurrently filtering particles and collecting gases. Materials are be added (e.g., via coating the ceramic substrate, use of loose powder(s), or other means) to a HEPA filter (ceramic, metal, or otherwise) to collect gases (e.g., radioactive gases such as iodine). The gases could be radioactive, hazardous, or valuable gases.

Copper(II)-rubeanic acid coprecipitation system for separation-preconcentration of trace metal ions in environmental samples for their flame atomic absorption spectrometric determinations.

PubMed

Soylak, Mustafa; Erdogan, Nilgun D

2006-09-21

A simple and facile preconcentration procedure based on the coprecipitation of trace heavy metal ions with copper(II)-rubeanic acid complex has been developed. The analytical parameters including pH, amounts of rubeanic acid, sample volume, etc. was investigated for the quantitative recoveries of Pb(II), Fe(III), Cd(II), Au(III), Pd(II) and Ni(II). No interferic effects were observed from the concomitant ions. The detection limits for analyte ions by 3 sigma were in the range of 0.14 microg/l for iron-3.4 microg/l for lead. The proposed coprecipitation method was successfully applied to water samples from Palas Lake-Kayseri, soil and sediment samples from Kayseri and Yozgat-Turkey.

Golf ball-assisted electrospray ionization of mass spectrometry for the determination of trace amino acids in complex samples.

PubMed

Li, Yen-Hsien; Chen, Chung-Yu; Kuo, Cheng-Hsiung; Lee, Maw-Rong

2016-09-28

During the electrospray ionization (ESI) process, ions move through a heated capillary aperture to be detected on arrival at a mass analyzer. However, the ESI process creates an ion plume, which expands into an ion cloud with an area larger than that of the heated capillary aperture, significantly contributing to an ion loss of 50% due to coulombic repulsion. The use of DC and RF fields to focus ions from the ion source into the vacuum chamber has been proposed in the literature, but the improvement of ion transmission efficiency is limited. To improve ion transmission, in this study we propose a novel method using a home-made golf ball positioned between the ion source and the inlet of the mass analyzer to hydrodynamically focus the ions passing through the golf ball. The ion plume produced by the ESI process passes through the golf ball will reduce the size of the ion cloud then be focused and most of them flowed into the mass analyzer. Therefore, the sensitivity will be improved, the aim of this investigation is to study the enhancing of the signal using golf ball-assisted electrospray ionization liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine 20 trace amino acids in complex samples, including tea, urine and serum. The results showed that the analytical performance of the determination of the 20 amino acids in tea, urine and serum samples using the home-made golf ball-assisted ESI source is better than that of a commercial ESI source. The signal intensities of the 20 amino acids were enhanced by factors of 2-2700, 11-2525, and 31-342680 in oolong tea, urine and serum analyses, respectively. The precision of the proposed method ranged from 1-9%, 0.4-9% and 0.4-8% at low, medium and high concentration levels of amino acids, respectively. The home-made golf ball-assisted ESI source effectively increased the signal intensity and enhanced the ion transmission efficiency and is also an easy, convenient and economical device. This technique can

Trace conditioning in insects—keep the trace!

PubMed Central

Dylla, Kristina V.; Galili, Dana S.; Szyszka, Paul; Lüdke, Alja

2013-01-01

Trace conditioning is a form of associative learning that can be induced by presenting a conditioned stimulus (CS) and an unconditioned stimulus (US) following each other, but separated by a temporal gap. This gap distinguishes trace conditioning from classical delay conditioning, where the CS and US overlap. To bridge the temporal gap between both stimuli and to form an association between CS and US in trace conditioning, the brain must keep a neural representation of the CS after its termination—a stimulus trace. Behavioral and physiological studies on trace and delay conditioning revealed similarities between the two forms of learning, like similar memory decay and similar odor identity perception in invertebrates. On the other hand differences were reported also, like the requirement of distinct brain structures in vertebrates or disparities in molecular mechanisms in both vertebrates and invertebrates. For example, in commonly used vertebrate conditioning paradigms the hippocampus is necessary for trace but not for delay conditioning, and Drosophila delay conditioning requires the Rutabaga adenylyl cyclase (Rut-AC), which is dispensable in trace conditioning. It is still unknown how the brain encodes CS traces and how they are associated with a US in trace conditioning. Insects serve as powerful models to address the mechanisms underlying trace conditioning, due to their simple brain anatomy, behavioral accessibility and established methods of genetic interference. In this review we summarize the recent progress in insect trace conditioning on the behavioral and physiological level and emphasize similarities and differences compared to delay conditioning. Moreover, we examine proposed molecular and computational models and reassess different experimental approaches used for trace conditioning. PMID:23986710

Noble gases in the moon

NASA Technical Reports Server (NTRS)

Manuel, O. K.; Srinivasan, B.; Hennecke, E. W.; Sinclair, D. E.

1972-01-01

The abundance and isotopic composition of helium, neon, argon, krypton, and xenon which were released by stepwise heating of lunar fines (15601.64) and (15271.65) were measured spectrometrically. The results of a composition of noble gases released from the lunar fines with noble gases in meteorites and in the earth are presented along with the isotopic composition of noble gases in lunar fines, in meteorites, and in the atmosphere. A study of two isotopically distinct components of trapped xenon in carbonaceous chondrites is also included.

110 Years of the Meyer–Overton Rule: Predicting Membrane Permeability of Gases and Other Small Compounds

PubMed Central

Missner, Andreas; Pohl, Peter

2010-01-01

The transport of gaseous compounds across biological membranes is essential in all forms of life. Although it was generally accepted that gases freely penetrate the lipid matrix of biological membranes, a number of studies challenged this doctrine as they found biological membranes to have extremely low gas-permeability values. These observations led to the identification of several membrane-embedded “gas” channels, which facilitate the transport of biological active gases, such as carbon dioxide, nitric oxide, and ammonia. However, some of these findings are in contrast to the well-established solubility–diffusion model (also known as the Meyer–Overton rule), which predicts membrane permeabilities from the molecule's oil–water partition coefficient. Herein, we discuss recently reported violations of the Meyer–Overton rule for small molecules, including carboxylic acids and gases, and show that Meyer and Overton continue to rule. PMID:19514034

Diffusion of cis-5,8,11,14,17-eicosapentaenoic acid (1); carbon dioxide (2)

NASA Astrophysics Data System (ADS)

Winkelmann, J.

This document is part of Subvolume A `Gases in Gases, Liquids and their Mixtures' of Volume 15 `Diffusion in Gases, Liquids and Electrolytes' of Landolt-Börnstein Group IV `Physical Chemistry'. It is part of the chapter of the chapter `Diffusion in Pure Gases' and contains data on diffusion of (1) cis-5,8,11,14,17-eicosapentaenoic acid; (2) carbon dioxide

Angular correlation studies in noble gases

NASA Technical Reports Server (NTRS)

Coleman, P. G.

1990-01-01

There has been a recent revival of interest in the measurement of angular correlation of annihilation photons from the decay of positrons and positronium in gases. This revival has been stimulated by the possibility offered by the technique to shed new light on the apparently low positronium formation fraction in the heavier noble gases and to provide information on positronium quenching processes in gases such as oxygen. There is also the potential for learning about positronium slowing down in gases. This review focuses on experimental noble gas work and considers what new information has been, and may be, gained from these studies.

Gas adsorption and desorption effects on high pressure small volume cylinders and their relevance to atmospheric trace gas analysis

NASA Astrophysics Data System (ADS)

Satar, Ece; Nyfeler, Peter; Pascale, Céline; Niederhauser, Bernhard; Leuenberger, Markus

2017-04-01

Long term atmospheric monitoring of trace gases requires great attention to precision and accuracy of the measurement setups. For globally integrated and well established greenhouse gas observation networks, the World Meteorological Organization (WMO) has set recommended compatibility goals within the framework of its Global Atmosphere Watch (GAW) Programme [1]. To achieve these challenging limits, the measurement systems are regularly calibrated with standard gases of known composition. Therefore, the stability of the primary and secondary gas standards over time is an essential issue. Past studies have explained the small instabilities in high pressure standard gas cylinders through leakage, diffusion, regulator effects, gravimetric fractionation and surface processes [2, 3]. The latter include adsorption/desorption, which are functions of temperature, pressure and surface properties. For high pressure standard gas mixtures used in atmospheric trace gas analysis, there exists only a limited amount of data and few attempts to quantify the surface processes [4, 5]. Specifically, we have designed a high pressure measurement chamber to investigate trace gases and their affinity for adsorption on different surfaces over various temperature and pressure ranges. Here, we focus on measurements of CO2, CH4 and CO using a cavity ring down spectroscopy analyzer and quantify the concentration changes due to adsorption/desorption. In this study, the first results from these prototype cylinders of steel and aluminum will be presented. References [1] World Meteorological Organization (WMO), Global Atmosphere Watch.(GAW): Report No. 229, 18th WMO/IAEA Meeting on Carbon Dioxide, Other Greenhouse Gases and Related Tracers Measurement Techniques (GGMT-2015), 2016. [2] Keeling, R. F., Manning, A. C., Paplawsky, W. J., and Cox, A. C.: On the long-term stability of reference gases for atmospheric O2 /N2 and CO2 measurements, Tellus B, 59, 10.3402/tellusb.v59i1.16964, 2007. [3

Trace gas fluxes from intensively managed rice and soybean fields across three growing seasons in the Brazilian Amazon

Treesearch

R.C. Oliveira Junior; Michael Keller; P. Crill; T. Beldini; J. Van Haren; P. Camargo

2015-01-01

The emission of gases that may potentially intensify the greenhouse effect has received special attention due to their ability to raise global temperatures and possibly modify conditions for life on earth. The objectives of this study were the quantification of trace gas flux (N2O, CO2 and CH4) in soils of the lower Amazon basin that are planted with rice and soybean,...

Irreversible sorption of trace concentrations of perfluorocarboxylic acids to fiber filters used for air sampling

NASA Astrophysics Data System (ADS)

Arp, Hans Peter H.; Goss, Kai-Uwe

Due to the apparent environmental omnipresence of perfluorocarboxylic acids (PFAs), an increasing number of researchers are investigating their ambient particle- and gas-phase concentrations. Typically this is done using a high-volume air sampler equipped with Quartz Fiber Filters (QFFs) or Glass Fiber Filters (GFFs) to sample the particle-bound PFAs and downstream sorbents to sample the gas-phase PFAs. This study reports that at trace, ambient concentrations gas-phase PFAs sorb to QFFs and GFFs irreversibly and hardly pass through these filters to the downstream sorbents. As a consequence, it is not possible to distinguish between particle- and gas-phase concentrations, or to distinguish concentrations on different particle size fractions, unless precautions are taken. Failure to take such precautions could have already caused reported data to be misinterpreted. Here it is also reported that deactivating QFFs and GFFs with a silylating agent renders them suitable for sampling PFAs. Based on the presented study, a series of recommendations for air-sampling PFAs are provided.

Airborne measurements and emission estimates of greenhouse gases and other trace constituents from the 2013 California Yosemite Rim wildfire

NASA Astrophysics Data System (ADS)

Yates, E. L.; Iraci, L. T.; Singh, H. B.; Tanaka, T.; Roby, M. C.; Hamill, P.; Clements, C. B.; Lareau, N.; Contezac, J.; Blake, D. R.; Simpson, I. J.; Wisthaler, A.; Mikoviny, T.; Diskin, G. S.; Beyersdorf, A. J.; Choi, Y.; Ryerson, T. B.; Jimenez, J. L.; Campuzano-Jost, P.; Loewenstein, M.; Gore, W.

2016-02-01

This paper presents airborne measurements of multiple atmospheric trace constituents including greenhouse gases (such as CO2, CH4, O3) and biomass burning tracers (such as CO, CH3CN) downwind of an exceptionally large wildfire. In summer 2013, the Rim wildfire, ignited just west of the Yosemite National Park, California, and burned over 250,000 acres of the forest during the 2-month period (17 August to 24 October) before it was extinguished. The Rim wildfire plume was intercepted by flights carried out by the NASA Ames Alpha Jet Atmospheric eXperiment (AJAX) on 29 August and the NASA DC-8, as part of SEAC4RS (Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys), on 26 and 27 August during its intense, primary burning period. AJAX revisited the wildfire on 10 September when the conditions were increasingly smoldering, with slower growth. The more extensive payload of the DC-8 helped to bridge key measurements that were not available as part of AJAX (e. g. CO). Data analyses are presented in terms of emission ratios (ER), emission factors (EF) and combustion efficiency and are compared with previous wildfire studies. ERs were 8.0 ppb CH4 (ppm CO2)-1 on 26 August, 6.5 ppb CH4 (ppm CO2)-1 on 29 August and 18.3 ppb CH4 (ppm CO2)-1 on 10 September 2013. The increase in CH4 ER from 6.5 to 8.0 ppb CH4 (ppm CO2)-1 during the primary burning period to 18.3 ppb CH4 (ppm CO2)-1 during the fire's slower growth period likely indicates enhanced CH4 emissions from increased smoldering combustion relative to flaming combustion. Given the magnitude of the Rim wildfire, the impacts it had on regional air quality and the limited sampling of wildfire emissions in the western United States to date, this study provides a valuable dataset to support forestry and regional air quality management, including observations of ERs of a wide number of species from the Rim wildfire.

[Significance of hydrocyanic acid formation during fires].

PubMed

von Meyer, L; Drasch, G; Kauert, G

1979-01-01

Cyanide concentrations of blood samples from fire victims autopsied in the Institute of Legal Medicine, Munich, have been determined. In 25% of 48 analyzed cases cyanide concentrations from 0.52 microgram to 6.24 microgram Cyanide/ml blood have been detected. These results are compared to former studies and the higher mean level in our collective is emphasized. The importance of hydrocyanid acid in the toxicity of fire gases is evidently greater, than assumed. Hydrocyanic acid may be produced from nitrogen continaing polymers during combustion. The quote of these polymers in clothing, furniture, and also in equipment of cars is increasing. Therefore, it is necessary to take more notice of the formation of hydrocyanic acid during combustion, even though carbon monoxide is in general the main toxic agent in fire gases.

Trace Contaminant Testing with the Orion Atmosphere Revitalization Technology

NASA Technical Reports Server (NTRS)

Button, Amy Lin; Sweterlitsch, Jeffrey; Broerman, Craig

2009-01-01

Every spacecraft atmosphere contains trace contaminants resulting from offgassing by cabin materials and human passengers. An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by Hamilton Sundstrand and baselined for the Orion Atmosphere Revitalization System (ARS). Part of the risk mitigation effort for this new technology is the study of how atmospheric trace contaminants will affect and be affected by the technology. One particular area of concern is ammonia, which, in addition to the normal spacecraft sources, can also be off-gassed by the amine-based sorbent. In the first half of 2009, tests were performed with typical cabin atmosphere levels of five of the most common trace gases, most of which had not yet been tested with this technology. A subscale sample of the sorbent was exposed to each of the chemicals mixed into a stream of moist, CO2-laden air, and the CO2 adsorption capacity of the sorbent was compared before and after the exposure. After these typical-concentration chemicals were proven to have negligible effect on the subscale sample, tests proceeded on a full-scale test article in a sealed chamber with a suite of eleven contaminants. To isolate the effects of various test rig components, several extended-duration tests were run: without injection or scrubbing, with injection and without scrubbing, with injection and scrubbing by both the test article and dedicated trace contaminant filters, and with injection and scrubbing by only the test article. The high-level results of both the subscale and full-scale tests are examined in this paper.

A new numerical model of the middle atmosphere. I - Dynamics and transport of tropospheric source gases

NASA Technical Reports Server (NTRS)

Garcia, Rolando R.; Stordal, Frode; Solomon, Susan; Kiehl, Jeffrey T.

1992-01-01

Attention is given to a new model of the middle atmosphere which includes, in addition to the equations governing the zonal mean state, a potential vorticity equation for a single planetary-scale Rossby wave, and an IR radiative transfer code for the stratosphere and lower mesosphere, which replaces the Newtonian cooling parameterization used previously. It is shown that explicit computation of the planetary-scale wave field yields a more realistic representation of the zonal mean dynamics and the distribution of trace chemical species. Wave breaking produces a well-mixed 'surf zone' equatorward of the polar night vortex and drives a meridional circulation with downwelling on the poleward side of the vortex. This combination of mixing and downwelling produces shallow meridional gradients of trace gases in the subtropics and middle latitudes, and very steep gradients at the edge of the polar vortex. Computed distributions of methane and nitrous oxide are shown to agree well with observations.

The effect of tissue structure and soil chemistry on trace element uptake in fossils

NASA Astrophysics Data System (ADS)

Hinz, Emily A.; Kohn, Matthew J.

2010-06-01

Trace element profiles for common divalent cations (Sr, Zn, Ba), rare-earth elements (REE), Y, U, and Th were measured in fossil bones and teeth from the c. 25 ka Merrell locality, Montana, USA, by using laser-ablation ICP-MS. Multiple traverses in teeth were transformed into 2-D trace element maps for visualizing structural influences on trace element uptake. Trace element compositions of different soils from the fossil site were also analyzed by solution ICP-MS, employing progressive leaches that included distilled H 2O, 0.1 M acetic acid, and microwave digestion in concentrated HCl-HNO 3. In teeth, trace element uptake in enamel is 2-4 orders of magnitude slower than in dentine, forming an effective trace element barrier. Uptake in dentine parallel to the dentine-enamel interface is enhanced by at least 2 orders of magnitude compared to transverse, causing trace element "plumes" down the tooth core. In bone, U, Ba and Sr are nearly homogeneous, implying diffusivities ˜5 orders of magnitude faster than in enamel and virtually complete equilibration with host soils. In contrast all REE show strong depletions inward, with stepwise linear segments in log-normal or inverse complementary error function plots; these data require a multi-medium diffusion model, with about 2 orders of magnitude difference in slowest vs. fastest diffusivities. Differences in REE diffusivities in bone (slow) vs. dentine (fast) reflect different partition coefficients ( Kd's). Although acid leaches and bulk digestion of soils yield comparable fossil-soil Kd's among different elements, natural solutions are expected to be neutral to slightly basic. Distilled H 2O leachates instead reveal radically different Kd's in bone for REE than for U-Sr-Ba, suggest orders of magnitude lower effective diffusivities for REE, and readily explain steep vs. flat profiles for REE vs. U-Sr-Ba, respectively. Differences among REE Kd's and diffusivities may explain inward changes in Ce anomalies. Acid washes

Production of a novel antioxidant furan fatty acid from 7,10-dihydroxy-8(E)-octadecenoic acid

USDA-ARS?s Scientific Manuscript database

Furan fatty acids (F-acids) have gained attention since they are known to play important roles in a variety of biological systems. Specifically F-acids are known to have strong antioxidant activity. Although widely distributed in most biological systems, F-acids are trace components and their biosyn...

Production of chemicals from C1 gases (CO, CO2) by Clostridium carboxidivorans.

PubMed

Fernández-Naveira, Ánxela; Abubackar, Haris Nalakath; Veiga, María C; Kennes, Christian

2017-03-01

Bioprocesses in conventional second generation biorefineries are mainly based on the fermentation of sugars obtained from lignocellulosic biomass or agro-industrial wastes. An alternative to this process consists in gasifying those same feedstocks or even other carbon-containing materials to obtain syngas which can also be fermented by some anaerobic bacteria to produce chemicals or fuels. Carbon monoxide, carbon dioxide and hydrogen, which are the main components of syngas, are also found in some industrial waste gases, among others in steel industries. Clostridium carboxidivorans is able to metabolise such gases to produce ethanol and higher alcohols, i.e. butanol and hexanol, following the Wood-Ljungdahl pathway. This does simultaneously allow the removal of volatile pollutants involved in climate change. The bioconversion is a two step process in which organic acids (acetate, butyrate, hexanoate) are produced first, followed by the accumulation of alcohols; although partial overlap in time of acids and alcohols production may sometimes take place as well. Several parameters, among others pH, temperature, or gas-feed flow rates in bioreactors, affect the bioconversion process. Besides, the accumulation of high concentrations of alcohols in the fermentation broth inhibits the growth and metabolic activity of C. carboxidivorans.

Noble Gases

NASA Astrophysics Data System (ADS)

Podosek, F. A.

2003-12-01

The noble gases are the group of elements - helium, neon, argon, krypton, xenon - in the rightmost column of the periodic table of the elements, those which have "filled" outermost shells of electrons (two for helium, eight for the others). This configuration of electrons results in a neutral atom that has relatively low electron affinity and relatively high ionization energy. In consequence, in most natural circumstances these elements do not form chemical compounds, whence they are called "noble." Similarly, much more so than other elements in most circumstances, they partition strongly into a gas phase (as monatomic gas), so that they are called the "noble gases" (also, "inert gases"). (It should be noted, of course, that there is a sixth noble gas, radon, but all isotopes of radon are radioactive, with maximum half-life a few days, so that radon occurs in nature only because of recent production in the U-Th decay chains. The factors that govern the distribution of radon isotopes are thus quite different from those for the five gases cited. There are interesting stories about radon, but they are very different from those about the first five noble gases, and are thus outside the scope of this chapter.)In the nuclear fires in which the elements are forged, the creation and destruction of a given nuclear species depends on its nuclear properties, not on whether it will have a filled outermost shell when things cool off and nuclei begin to gather electrons. The numerology of nuclear physics is different from that of chemistry, so that in the cosmos at large there is nothing systematically special about the abundances of the noble gases as compared to other elements. We live in a very nonrepresentative part of the cosmos, however. As is discussed elsewhere in this volume, the outstanding generalization about the geo-/cosmochemistry of the terrestrial planets is that at some point thermodynamic conditions dictated phase separation of solids from gases, and that the

The potential role of magmatic gases in the genesis of Illinois- Kentucky fluorspar deposits: implications from chemical reaction path modeling

USGS Publications Warehouse

Plumlee, G.S.; Goldhaber, M.B.; Rowan, E.L.

1995-01-01

Presents results of reaction path calculations using the chemical speciation and reaction path program SOLVEQ and CHILLER to model possible fluorite deposition mechanisms in the Illinois-Kentucky fluorspar district. The results indicate that the fluids responsible for Illinois-Kentucky fluorspar mineralization were most likely quite acidic (pH < 4) and rich in fluorine in order to produce the fluorite-rich, dolomite-poor mineral assemblages and extensive dissolution of host limestones. A possible source for the acid and fluorine may have been HF-rich gases which were expelled from alkalic magmas and then incorporated by migrating basinal brines. An analysis of the geologic setting of other fluorite deposits and districts worldwide suggests that involvement of magmatic gases is probable for many of these districts as well. -from Authors

REDUCTION OF ACIDITY OF NITRIC ACID SOLUTIONS BY USE OF FORMALDEHYDE

DOEpatents

Healy, T.V.

1958-05-20

A continuous method is described of concentrating by evaporation and reducing the nitrate ion content of an aqueous solution of metallic salts containing nitric acid not in excess of 8N. It consists of heating the solution and then passing formaldehyde into the heated solution to bring about decomposition of the nitric acid. The evolved gases containing NO are contacted countercurrently with an aqueous metal salt solution containing nitric acid in excess of 8N so as to bring about decomposition of the nitric acid and lower the normality to at least 8N, whereupon it is passed into the body of heated solution.

Long term aerosol and trace gas measurements in Central Amazonia

NASA Astrophysics Data System (ADS)

Artaxo, Paulo; Barbosa, Henrique M. J.; Ferreira de Brito, Joel; Carbone, Samara; Rizzo, Luciana V.; Andreae, Meinrat O.; Martin, Scot T.

2016-04-01

The central region of the Amazonian forest is a pristine region in terms of aerosol and trace gases concentrations. In the wet season, Amazonia is actually one of the cleanest continental region we can observe on Earth. A long term observational program started 20 years ago, and show important features of this pristine region. Several sites were used, between then ATTO (Amazon Tall Tower Observatory) and ZF2 ecological research site, both 70-150 Km North of Manaus, receiving air masses that traveled over 1500 km of pristine tropical forests. The sites are GAW regional monitoring stations. Aerosol chemical composition (OC/EC and trace elements) is being analysed using filters for fine (PM2.5) and coarse mode aerosol as well as Aerodyne ACSM (Aerosol Chemical Speciation Monitors). VOCs are measured using PTR-MS, while CO, O3 and CO2 are routinely measured. Aerosol absorption is being studied with AE33 aethalometers and MAAP (Multi Angle Absorption Photometers). Aerosol light scattering are being measured at several wavelengths using TSI and Ecotech nephelometers. Aerosol size distribution is determined using scanning mobility particle sizer at each site. Lidars measure the aerosol column up to 12 Km providing the vertical profile of aerosol extinction. The aerosol column is measures using AERONET sun photometers. In the wet season, organic aerosol comprises 75-85% of fine aerosol, and sulfate and nitrate concentrations are very low (1-3 percent). Aerosols are dominated by biogenic primary particles as well as SOA from biogenic precursors. Black carbon in the wet season accounts for 5-9% of fine mode aerosol. Ozone in the wet season peaks at 10-12 ppb at the middle of the day, while carbon monoxide averages at 50-80 ppb. Aerosol optical thickness (AOT) is a low 0.05 to 0.1 at 550 nm in the wet season. Sahara dust transport events sporadically enhance the concentration of soil dust aerosols and black carbon. In the dry season (August-December), long range transported

Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE): emissions of trace gases and light-absorbing carbon from wood and dung cooking fires, garbage and crop residue burning, brick kilns, and other sources

NASA Astrophysics Data System (ADS)

Stockwell, Chelsea E.; Christian, Ted J.; Goetz, J. Douglas; Jayarathne, Thilina; Bhave, Prakash V.; Praveen, Puppala S.; Adhikari, Sagar; Maharjan, Rashmi; DeCarlo, Peter F.; Stone, Elizabeth A.; Saikawa, Eri; Blake, Donald R.; Simpson, Isobel J.; Yokelson, Robert J.; Panday, Arnico K.

2016-09-01

The Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE) campaign took place in and around the Kathmandu Valley and in the Indo-Gangetic Plain (IGP) of southern Nepal during April 2015. The source characterization phase targeted numerous important but undersampled (and often inefficient) combustion sources that are widespread in the developing world such as cooking with a variety of stoves and solid fuels, brick kilns, open burning of municipal solid waste (a.k.a. trash or garbage burning), crop residue burning, generators, irrigation pumps, and motorcycles. NAMaSTE produced the first, or rare, measurements of aerosol optical properties, aerosol mass, and detailed trace gas chemistry for the emissions from many of the sources. This paper reports the trace gas and aerosol measurements obtained by Fourier transform infrared (FTIR) spectroscopy, whole-air sampling (WAS), and photoacoustic extinctiometers (PAX; 405 and 870 nm) based on field work with a moveable lab sampling authentic sources. The primary aerosol optical properties reported include emission factors (EFs) for scattering and absorption coefficients (EF Bscat, EF Babs, in m2 kg-1 fuel burned), single scattering albedos (SSAs), and absorption Ångström exponents (AAEs). From these data we estimate black and brown carbon (BC, BrC) emission factors (g kg-1 fuel burned). The trace gas measurements provide EFs (g kg-1) for CO2, CO, CH4, selected non-methane hydrocarbons up to C10, a large suite of oxygenated organic compounds, NH3, HCN, NOx, SO2, HCl, HF, etc. (up to ˜ 80 gases in all). The emissions varied significantly by source, and light absorption by both BrC and BC was important for many sources. The AAE for dung-fuel cooking fires (4.63 ± 0.68) was significantly higher than for wood-fuel cooking fires (3.01 ± 0.10). Dung-fuel cooking fires also emitted high levels of NH3 (3.00 ± 1.33 g kg-1), organic acids (7.66 ± 6.90 g kg-1), and HCN (2.01 ± 1.25 g kg-1), where the latter could

Emission rates of sulfur dioxide, trace gases and metals from Mount Erebus, Antartica

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

Kyle, P.R.; Meeker, K.; Finnegan, D.

1990-11-01

SO{sub 2} emission rates have been measured annually since 1983 at Mount Erebus, Antarctica by correlation spectrometer (COSPEC V). Following a 4 month period of sustained strombolian activity in late 1984, SO{sub 2} emissions declined from 230 Mg/day in 1983 to 25 Mg/day and then slowly increased from 16 Mg/day in 1985 to 51 Mg/day in 1987. Nine sets of filter packs containing partcle and {sup 7}LiOH treated filters were collected in the plume in 1986 and analyzed by neutron activation. Using the COSPEC data and measured element/S ratios on the filters, emission rates have been determined for trace gasesmore » and metals. The authors infer HCl and HF emissions in 1983 to be about 1200 and 500 Mg/day, respectively. Mt Erebus has therefore been an important source of halogens to the Anarctic atmosphere and could be responsible for excess Cl found in Central Antarctica snow.« less

Particulate and trace gas emissions from prescribed burns in southeastern U.S. fuel types: Summary of a 5-year project

Treesearch

David R. Weise; Timothy J. Johnson; James Reardon

2015-01-01

Management of smoke from prescribed fires requires knowledge of fuel quantity and the amount and composition of the smoke produced by the fire to minimize adverse impacts on human health. A five-year study produced new emissions information for more than 100 trace gases and particulate matter in smoke for fuel types found in the southern United States of America using...

Research of medical gases in Poland

PubMed Central

2013-01-01

Research of medical gases is well established in Poland and has been marked with the foundation of several professional societies. Numerous academic centers including those dealing with hyperbaric and diving medicine conduct studies of medical gases, in vast majority supported with intramural funds. In general, Polish research of medical gases is very much clinical in nature, covering new applications and safety of medical gases in medicine; on the other hand there are several academic centers pursuing preclinical studies, and elaborating basic theories of gas physiology and mathematical modeling of gas exchange. What dominates is research dealing with oxygen and ozone as well as studies of anesthetic gases and their applications. Finally, several research directions involving noble gas, hydrogen and hydrogen sulfide for cell protection, only begin to gain recognition of basic scientists and clinicians. However, further developments require more monetary spending on research and clinical testing as well as formation of new collective bodies for coordinating efforts in this matter. PMID:23916016

Mercury transformation and speciation in flue gases from anthropogenic emission sources: a critical review

NASA Astrophysics Data System (ADS)

Zhang, Lei; Wang, Shuxiao; Wu, Qingru; Wang, Fengyang; Lin, Che-Jen; Zhang, Leiming; Hui, Mulin; Yang, Mei; Su, Haitao; Hao, Jiming

2016-02-01

Mercury transformation mechanisms and speciation profiles are reviewed for mercury formed in and released from flue gases of coal-fired boilers, non-ferrous metal smelters, cement plants, iron and steel plants, waste incinerators, biomass burning and so on. Mercury in coal, ores, and other raw materials is released to flue gases in the form of Hg0 during combustion or smelting in boilers, kilns or furnaces. Decreasing temperature from over 800 °C to below 300 °C in flue gases leaving boilers, kilns or furnaces promotes homogeneous and heterogeneous oxidation of Hg0 to gaseous divalent mercury (Hg2+), with a portion of Hg2+ adsorbed onto fly ash to form particulate-bound mercury (Hgp). Halogen is the primary oxidizer for Hg0 in flue gases, and active components (e.g., TiO2, Fe2O3, etc.) on fly ash promote heterogeneous oxidation and adsorption processes. In addition to mercury removal, mercury transformation also occurs when passing through air pollution control devices (APCDs), affecting the mercury speciation in flue gases. In coal-fired power plants, selective catalytic reduction (SCR) system promotes mercury oxidation by 34-85 %, electrostatic precipitator (ESP) and fabric filter (FF) remove over 99 % of Hgp, and wet flue gas desulfurization system (WFGD) captures 60-95 % of Hg2+. In non-ferrous metal smelters, most Hg0 is converted to Hg2+ and removed in acid plants (APs). For cement clinker production, mercury cycling and operational conditions promote heterogeneous mercury oxidation and adsorption. The mercury speciation profiles in flue gases emitted to the atmosphere are determined by transformation mechanisms and mercury removal efficiencies by various APCDs. For all the sectors reviewed in this study, Hgp accounts for less than 5 % in flue gases. In China, mercury emission has a higher Hg0 fraction (66-82 % of total mercury) in flue gases from coal combustion, in contrast to a greater Hg2+ fraction (29-90 %) from non-ferrous metal smelting, cement and

Mercury transformation and speciation in flue gases from anthropogenic emission sources: a critical review

NASA Astrophysics Data System (ADS)

Zhang, L.; Wang, S. X.; Wu, Q. R.; Wang, F. Y.; Lin, C.-J.; Zhang, L. M.; Hui, M. L.; Hao, J. M.

2015-11-01

Mercury transformation mechanisms and speciation profiles are reviewed for mercury formed in and released from flue gases of coal-fired boilers, non-ferrous metal smelters, cement plants, iron and steel plants, municipal solid waste incinerators, and biomass burning. Mercury in coal, ores and other raw materials is released to flue gases in the form of Hg0 during combustion or smelting in boilers, kilns or furnaces. Decreasing temperature from over 800 °C to below 300 °C in flue gases leaving boilers, kilns or furnaces promotes homogeneous and heterogeneous oxidation of gaseous elemental mercury (Hg0) to gaseous divalent mercury (Hg2+), with a portion of Hg2+ adsorbed onto fly ash to form particulate-bound mercury (Hgp). Halogen is the primary oxidizer for Hg0 in flue gases, and active components (e.g.,TiO2, Fe2O3, etc.) on fly ash promote heterogeneous oxidation and adsorption processes. In addition to mercury removal, mercury transformation also occurs when passing through air pollution control devices (APCDs), affecting the mercury speciation in flue gases. In coal-fired power plants, selective catalytic reduction (SCR) system promotes mercury oxidation by 34-85 %, electrostatic precipitator (ESP) and fabric filter (FF) remove over 99 % of Hgp, and wet flue gas desulfurization system (WFGD) captures 60-95 % of Hg2+. In non-ferrous metal smelters, most Hg0 is converted to Hg2+ and removed in acid plants (APs). For cement clinker production, mercury cycling and operational conditions promote heterogeneous mercury oxidation and adsorption. The mercury speciation profiles in flue gases emitted to the atmosphere are determined by transformation mechanisms and mercury removal efficiencies by various APCDs. For all the sectors reviewed in this study, Hgp accounts for less than 5 % in flue gases. In China, mercury emission has a higher fraction (66-82 % of total mercury) in flue gases from coal combustion, in contrast to a greater Hg2+ fraction (29-90 %) from non

Optical fiber Fabry-Perot interferometer with pH sensitive hydrogel film for hazardous gases sensing

NASA Astrophysics Data System (ADS)

Zheng, Yangzi; Chen, Li Han; Chan, Chi Chiu; Dong, Xinyong; Yang, Jingyi; Tou, Zhi Qiang; So, Ping Lam

2015-09-01

An optical fiber Fabry-Perot interferometer (FPI) coated with polyvinyl alcohol/poly-acrylic acid (PVA/PAA) hydrogel film for toxic gases measurement has been developed. Splicing a short section of hollow core fiber between two single mode fibers forms the FPI. Dip-coated pH-sensitive PVA/PAA hydrogel film on the fiber end performs as a receptor for binding of volatile acids or ammonia, which makes the sensing film swelling or shrinking and results in the dip wavelength shift of the FPI. By demodulating the evolution of reflection spectrum for various concentrations of volatile acids, a sensitivity of 20.8 nm/ppm is achieved with uniform linearity.

Voluntary Reporting of Greenhouse Gases

EIA Publications

2011-01-01

The Voluntary Reporting of Greenhouse Gases Program was suspended May 2011. It was a mechanism by which corporations, government agencies, individuals, voluntary organizations, etc., could report to the Energy Information Administration, any actions taken that have or are expected to reduce/avoid emissions of greenhouse gases or sequester carbon.

Markers for Chinese and Korean Air Masses: Halocarbons and Other Trace Gases Measured During KORUS-AQ

NASA Astrophysics Data System (ADS)

Blake, N. J.; Blake, D. R.; Meinardi, S.; Simpson, I. J.; Hughes, S.; Barletta, B.; Fleming, L.; Vizenor, N.; Schroeder, J.; Emmons, L. K.; Knote, C. J.

2017-12-01

The UC-Irvine Whole Air Sampler (WAS) collected a total of 2650 samples aboard the NASA DC-8 aircraft in support of the May-June 2016 field deployment phase of the KORUS-AQ mission: An International Cooperative Air Quality Field Study in Korea. Here we employ our trace gas measurements, along with CAM-chem tracers and back-trajectories to identify source regions during KORUS-AQ, with a focus on air masses which indicate Chinese and/or Korean origin. During KORUS-AQ we flew mostly over and around the Korean Peninsula with the intent of characterising Korean sources, but Chinese influence was observed offshore near the surface of the West Sea during several KORUS-AQ flights - in accord with forecast predictions from CAM-chem model runs. Unlike previous missions in the Asian region such as TRACE-P (2001), we found that halon-1211 (H-1211) is no longer a useful indicator of air masses from China because of production decline. By contrast, mixing ratios of the long-lived halocarbons carbon tetrachloride (CCl4) and chlorofluorocarbon-113 (CFC-113) were more strongly enhanced in air masses intercepted from China compared to Korea. We will use these tracers, the shorter-lived halocarbons, dichloromethane (CH2Cl2) and methyl chloride (CH3Cl), as well as the sulfur gas carbonyl sulfide (COS) and others, to characterize different regional air mass origins and their sources.

Major to ultra trace elements in rainfall collected in suburban Tokyo

NASA Astrophysics Data System (ADS)

Shimamura, Tadashi; Iwashita, Masato; Iijima, Satoe; Shintani, Megumi; Takaku, Yuichi

Major to ultra trace elements such as rare earth elements (REEs), platinum group elements (PGEs) in 20 rainfall events from suburban Tokyo were determined by inductively coupled plasma mass spectrometry (ICP-MS). Anion species were also determined by an ion chromatography (IC). The concentrations of PGEs were so low that only Pt was detected in some rainfall events. Enrichment factors (EFs), refer to soil and sea salt components, were calculated for the measured elements (with Al and Na as references). Be, (Na), Mg, (Al), Si, Cl, K, Fe, Rb, Sr, REEs (except La, Gd), Ta, and U were mostly originated from natural materials (soil and sea salt). For Li, B, Ca, Mn, Sr, Ba, and Cs, the contribution of natural materials was significant. EFs for Cu, Zn, As, Se, Sb, Cd, Pb, Bi, Ag, Te, Au, Pt, SO 4-S and NO 3-N exceeded 100 indicating non-crustal, non-sea salt origin, presumably anthropogenic; however, contribution of volcanic gases could not be excluded for As, Se, Te and Bi. Pt seemed to be uniformly distributed worldwide and a catalyst for automobile emission control may be the main source. Au also showed uniform distribution. On the other hand, EFs for Zr, Nb, Hf and Th were less than unity. Probably these elements resided in acid resistant refractory fine minerals that did not decompose with acid treatment, and did not evaporate and ionize in the ICP. An alternative explanation is that the concentration of these elements was lower in the soil of the sampling area than the average crust. In the crust normalized REE pattern plot, La, Eu and Gd showed clear positive anomalies. La and Gd could have anthropogenic components. A possible source of La and Gd is cracking catalyst for petrol refining, but this source does not fully explain the anomaly. The source of Gd may also be Gd-DTPA (Gadolinium (III) diethyltriaminepentaacetic acid) used for Magnetic Resonance Imaging (MRI) contrast agents. The Eu origin may be soil with higher concentration than the crust average.

Reale Gase, tiefe Temperaturen

NASA Astrophysics Data System (ADS)

Heintze, Joachim

Wir werden uns in diesem Kapitel zunächst mit der van der Waals'schen Zustandsgleichung befassen. In dieser Gleichung wird versucht, die Abweichungen, die reale Gase vom Verhalten idealer Gase zeigen, durch physikalisch motivierte Korrekturterme zu berücksichtigen. Es zeigt sich, dass die van derWaals-Gleichung geeignet ist, nicht nur die Gasphase, sondern auch die Phänomene bei der Verflüssigung von Gasen und den kritischen Punkt zu beschreiben.

Denitrification of combustion gases. [Patent application

DOEpatents

Yang, R.T.

1980-10-09

A method for treating waste combustion gas to remove the nitrogen oxygen gases therefrom is disclosed wherein the waste gas is first contacted with calcium oxide which absorbs and chemically reacts with the nitrogen oxide gases therein at a temperature from about 100/sup 0/ to 430/sup 0/C. The thus reacted calcium oxide (now calcium nitrate) is then heated at a temperature range between about 430/sup 0/ and 900/sup 0/C, resulting in regeneration of the calcium oxide and production of the decomposition gas composed of nitrogen and nitrogen oxide gas. The decomposition gases can be recycled to the calcium oxide contacting step to minimize the amount of nitrogen oxide gases in the final product gas.

Scaling up in the face of uncertainty - controls on trace gas fluxes in heterogeneous landscapes (Invited)

NASA Astrophysics Data System (ADS)

Bernhardt, E. S.; Helton, A. M.; Morse, J. L.; Poole, G. C.

2013-12-01

Wetlands are the dominant natural source of methane to the global atmosphere and can be important sites of either N2O emission or consumption. Changes in the spatial extent or inundation frequency and duration may lead to substantial shifts in the contribution of wetland ecosystems to global CH4 and N2O emissions. Trace gases are produced at the scale of individual microbes, each of which respond dynamically to the local availability of electron donors and acceptors. Within landscape patches, substrate supply and redox conditions are strongly controlled by variation in water table elevation and vertical hydrologic exchange. At the landscape scale, lateral exchange between patches and the extent and duration of inundation. Accurate estimates of trace gas emissions from wetlands are hard to estimate given the dynamic patterns of redox potential within the soil column and across the landscape that redistribute electron donors and acceptors both vertically and laterally. In five years of trace gas flux measurement and modeling at TOWER, a 440 ha restored wetland in coastal NC, we have developed both simulation and statistical models to estimate landscape level trace gas fluxes. Yet, because trace gas emissions are highly variable in both time and space, our qualitative and quantitative attempts at upscaling trace gas emissions typically generate estimates with extremely high uncertainty. In this talk we will explore the challenges inherent to the estimation of landscape scale trace gas fluxes at the scale of our individual ecosystem as well as the difficulties in extrapolating across multiple ecosystem studies.

Trace gas emissions from biomass burning in tropical Australian savannas

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

Hurst, D.F.; Griffith, D.W.T.; Cook, G.D.

1994-08-20

The trace gas emissions of biomass burning was measured during the 1991 and 1992 dry seasons (April through October) at the Kapalga Research Station in Kakadu National Park, Northern Territory, Australia. Over 100 smoke samples from savannah fires were collected, from the ground and from aircraft flying at 50 to 700 meters above the fires. The samples were analyzed for carbon dioxide, carbon monoxide, nitrous oxides, and other carbon and nitrogen compounds using gas phase Fourier transform infrared (FTIR) spectroscopy, matrix isolation FTIR spectroscopy, and chemiluminescence techniques. This paper describes the results of the gas analyses and discusses the potentialmore » impacts of these gases on regional atmospheric chemistry.49 refs., 4 figs., 7 tabs.« less

Airway exchange of highly soluble gases.

PubMed

Hlastala, Michael P; Powell, Frank L; Anderson, Joseph C

2013-03-01

Highly blood soluble gases exchange with the bronchial circulation in the airways. On inhalation, air absorbs highly soluble gases from the airway mucosa and equilibrates with the blood before reaching the alveoli. Highly soluble gas partial pressure is identical throughout all alveoli. At the end of exhalation the partial pressure of a highly soluble gas decreases from the alveolar level in the terminal bronchioles to the end-exhaled partial pressure at the mouth. A mathematical model simulated the airway exchange of four gases (methyl isobutyl ketone, acetone, ethanol, and propylene glycol monomethyl ether) that have high water and blood solubility. The impact of solubility on the relative distribution of airway exchange was studied. We conclude that an increase in water solubility shifts the distribution of gas exchange toward the mouth. Of the four gases studied, ethanol had the greatest decrease in partial pressure from the alveolus to the mouth at end exhalation. Single exhalation breath tests are inappropriate for estimating alveolar levels of highly soluble gases, particularly for ethanol.

Airway exchange of highly soluble gases

PubMed Central

Powell, Frank L.; Anderson, Joseph C.

2013-01-01

Highly blood soluble gases exchange with the bronchial circulation in the airways. On inhalation, air absorbs highly soluble gases from the airway mucosa and equilibrates with the blood before reaching the alveoli. Highly soluble gas partial pressure is identical throughout all alveoli. At the end of exhalation the partial pressure of a highly soluble gas decreases from the alveolar level in the terminal bronchioles to the end-exhaled partial pressure at the mouth. A mathematical model simulated the airway exchange of four gases (methyl isobutyl ketone, acetone, ethanol, and propylene glycol monomethyl ether) that have high water and blood solubility. The impact of solubility on the relative distribution of airway exchange was studied. We conclude that an increase in water solubility shifts the distribution of gas exchange toward the mouth. Of the four gases studied, ethanol had the greatest decrease in partial pressure from the alveolus to the mouth at end exhalation. Single exhalation breath tests are inappropriate for estimating alveolar levels of highly soluble gases, particularly for ethanol. PMID:23305981

Online recording of ethane traces in human breath via infrared laser spectroscopy.

PubMed

von Basum, Golo; Dahnke, Hannes; Halmer, Daniel; Hering, Peter; Mürtz, Manfred

2003-12-01

A method is described for rapidly measuring the ethane concentration in exhaled human breath. Ethane is considered a volatile marker for lipid peroxidation. The breath samples are analyzed in real time during single exhalations by means of infrared cavity leak-out spectroscopy. This is an ultrasensitive laser-based method for the analysis of trace gases on the sub-parts per billion level. We demonstrate that this technique is capable of online quantifying of ethane traces in exhaled human breath down to 500 parts per trillion with a time resolution of better than 800 ms. This study includes what we believe to be the first measured expirograms for trace fractions of ethane. The expirograms were recorded after a controlled inhalation exposure to 1 part per million of ethane. The normalized slope of the alveolar plateau was determined, which shows a linear increase over the first breathing cycles and ends in a mean value between 0.21 and 0.39 liter-1. The washout process was observed for a time period of 30 min and was modelled by a threefold exponential decay function, with decay times ranging from 12 to 24, 341 to 481, and 370 to 1770 s. Our analyzer provides a promising noninvasive tool for online monitoring of the oxidative stress status.

Trace Contaminant Testing with the Orion Atmosphere Revitalization Technology

NASA Technical Reports Server (NTRS)

Button, Amy B.; Sweterlitsch, Jeffrey J.; Broerman, Craig D.; Campbell, Melissa L.

2010-01-01

Every spacecraft atmosphere contains trace contaminants resulting from offgassing by cabin materials and human passengers. An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by Hamilton Sundstrand and baselined for the Orion Atmosphere Revitalization System (ARS). Part of the risk mitigation effort for this new technology is the study of how atmospheric trace contaminants will affect and be affected by the technology. One particular area of concern is ammonia, which, in addition to the normal spacecraft sources, can also be offgassed by the amine-based sorbent. In the spring of 2009, tests were performed at Johnson Space Center (JSC) with typical cabin atmosphere levels of five of the most common trace gases, most of which had not yet been tested with this technology. A subscale sample of the sorbent was exposed to each of the chemicals mixed into a stream of moist, CO2-laden air, and the CO2 adsorption capacity of the sorbent was compared before and after the exposure. After these typical-concentration chemicals were proven to have negligible effect on the subscale sample, tests proceeded on a full-scale test article in a sealed chamber with a suite of eleven contaminants. To isolate the effects of various test rig components, several extended-duration tests were run: without injection or scrubbing, with injection and without scrubbing, with injection of both contaminants and metabolic CO2 and water vapor loads and scrubbing by both the test article and dedicated trace contaminant filters, and with the same injections and scrubbing by only the test article. The high-level results of both the subscale and full-scale tests are examined in this paper.

Gases as Idealized Lattices: A Rational Reconstruction of Students' Understanding of the Behavior of Gases.

ERIC Educational Resources Information Center

Niaz, Mansoor

2000-01-01

Establishes a relationship between students' understanding of gases and its parallels in the history of science. Finds that college freshman students' alternative conceptions about gas behavior are resistant to change and recapitulate theories scientists held in the past, such as the Lattice Theory of Gases. (Contains 52 references.) (Author/WRM)

Trace elements in soil and biota in confined disposal facilities for dredged material

USGS Publications Warehouse

Beyer, W.N.; Miller, G.; Simmers, J.W.

1990-01-01

We studied the relation of trace element concentrations in soil to those in house mice (Mus musculus), common reed (Phragmites australis) and ladybugs (Coccinella septempunctata) at five disposal facilities for dredged material. The sites had a wide range of soil trace element concentrations, acid soils and a depauperate fauna. They were very poor wildlife habitat because they were dominated by the common reed. Bioassay earthworms exposed to surface soils from three of the five sites died, whereas those exposed to four of five soils collected a meter deep survived, presumably because the deeper, unoxidized soil, was not as acid. Concentrations of Ni and Cr in the biota from each of the sites did not seem to be related to the concentrations of the same elements in soil. Although Pb, Zn and Cu concentrations in biota were correlated with those in soil, the range of concentrations in the biota was quite small compared to that in soil. The concentrations of Pb detected in mice were about as high as the concentrations previously reported in control mice from other studies. Mice from the most contaminated site (530 ppm Pb in soil) contained only slightly more Pb (8 ppm dry wt) than did mice (2-6 ppm dry wt) from sites containing much less Pb (22-92 ppm in soil). Despite the acid soil conditions, very little Cd was incorporated into food chains. Rather, Cd was leaching from the surface soil. We concluded that even the relatively high concentrations of trace elements in the acid dredged material studied did not cause high, concentrations of trace elements in the biota.

Trace gas detection from fermentation processes in apples; an intercomparison study between proton-transfer-reaction mass spectrometry and laser photoacoustics

NASA Astrophysics Data System (ADS)

Boamfa, E. I.; Steeghs, M. M. L.; Cristescu, S. M.; Harren, F. J. M.

2004-12-01

A custom-built proton-transfer-reaction mass spectrometry (PTR-MS) instrument was used to monitor the emission of various compounds (aldehydes, alcohols, acids, acetates and C-6 compounds) related to fermentation, aroma and flavour, released by four apple cultivars (Elstar, Jonaglod, Granny Smith and Pink Lady) under short anaerobic (24 h) and post-anaerobic conditions. The novel feature of our instrument is the new design of the collisional dissociation chamber, which separates the high pressure in the drift tube (2 mbar) from the high vacuum pressure in the detection region (10-6 mbar). The geometry of this chamber was changed and a second turbo pump was added to reduce the influence of collisional loss of ions, background signals and cluster ions, which facilitates the interpretation of the mass spectra and increases the signal intensity at the mass of the original protonated compound. With this system, detection limits of similar magnitude to the ones reported in literature are reached. An intercomparison study between PTR-MS and a CO laser-based photoacoustic trace gas detector is presented. The alcoholic fermentation products (acetaldehyde and ethanol) from young rice plants were simultaneously monitored by both methods. A very good agreement was observed for acetaldehyde production. The photoacoustic detector showed about two times lower ethanol concentration as compared to PTR-MS, caused by memory effects due to sticking of compounds to the walls of the nylon tube used to transport the trace gases to the detector.

Trace Amounts of Furan-2-Carboxylic Acids Determine the Quality of Solid Agar Plates for Bacterial Culture

PubMed Central

Hara, Shintaro; Isoda, Reika; Tahvanainen, Teemu; Hashidoko, Yasuyuki

2012-01-01

Background Many investigators have recognised that a significant proportion of environmental bacteria exist in a viable but non-culturable state on agar plates, and some researchers have also noticed that some of such bacteria clearly recover their growth on matrices other than agar. However, the reason why agar is unsuitable for the growth of some bacteria has not been addressed. Methodology/Principal Findings According to the guide of a bioassay for swarming inhibition, we identified 5-hydroxymethylfuran-2-carboxylic acid (5-HMFA) and furan-2-carboxylic acid (FA) as factors that inhibit bacterial swarming and likely inhibit extracellular polysaccharide production on agar. The furan-2-carboxylic acids 5-HMFA and FA effectively inhibited the swarming and swimming of several environmental bacteria at concentrations of 1.8 and 2.3 µg L−1 (13 and 21 nmol L−1), respectively, which are equivalent to the concentrations of these compounds in 0.3% agar. On Luria-Bertani (LB) plates containing 1.0% agar that had been previously washed with MeOH, a mixture of 5-HMFA and FA in amounts equivalent to their original concentrations in the unwashed agar repressed the swarming of Escherichia coli K12 strain W3110, a representative swarming bacterium. Conclusions/Significance Agar that contains trace amounts of 5-HMFA and FA inhibits the proliferation of some slow-growing or difficult-to-culture bacteria on the plates, but it is useful for single colony isolation due to the ease of identification of swarmable bacteria as the non-swarmed colonies. PMID:22848437

Trace metal mobilization from oil sands froth treatment thickened tailings exhibiting acid rock drainage.

PubMed

Kuznetsova, Alsu; Kuznetsov, Petr; Foght, Julia M; Siddique, Tariq

2016-11-15

Froth treatment thickened tailings (TT) are a waste product of bitumen extraction from surface-mined oil sands ores. When incubated in a laboratory under simulated moist oxic environmental conditions for ~450d, two different types of TT (TT1 and TT2) exhibited the potential to generate acid rock drainage (ARD) by producing acid leachate after 250 and 50d, respectively. We report here the release of toxic metals from TT via ARD, which could pose an environmental threat if oil sands TT deposits are not properly managed. Trace metal concentrations in leachate samples collected periodically revealed that Mn and Sr were released immediately even before the onset of ARD. Spikes in Co and Ni concentrations were observed both pre-ARD and during active ARD, particularly in TT1. For most elements measured (Fe, Cr, V, As, Cu, Pb, Zn, Cd, and Se), leaching was associated with ARD production. Though equivalent acidification (pH2) was achieved in leachate from both TT types, greater metal release was observed from TT2 where concentrations reached 10,000ppb for Ni, 5000ppb for Co, 3000ppb for As, 2000ppb for V, and 1000ppb for Cr. Generally, metal concentrations decreased in leachate with time during ARD and became negligible by the end of incubation (~450d) despite appreciable metals remaining in the leached TT. These results suggest that using TT for land reclamation purposes or surface deposition for volume reduction may unfavorably impact the environment, and warrants application of appropriate strategies for management of pyrite-enriched oil sands tailings streams. Copyright © 2016 Elsevier B.V. All rights reserved.

MRI using hyperpolarized noble gases.

PubMed

Kauczor, H; Surkau, R; Roberts, T

1998-01-01

The aim of this study was to review the physical basis of MRI using hyperpolarized noble gases as well as the present status of preclinical and clinical applications. Non-radioactive noble gases with a nuclear spin 1/2 (He-3, Xe-129) can be hyperpolarized by optical pumping. Polarization is transferred from circularly polarized laser light to the noble-gas atoms via alkali-metal vapors (spin exchange) or metastable atoms (metastability exchange). Hyperpolarization results in a non-equilibrium polarization five orders of magnitude higher than the Boltzmann equilibrium compensating for the several 1000 times lower density of noble gases as compared with liquid state hydrogen concentrations in tissue and allows for short imaging times. Hyperpolarization can be stored sufficiently long (3 h to 6 days) to allow for transport and application. Magnetic resonance systems require a broadband radio-frequency system - which is generally available for MR spectroscopy - and dedicated coils. The hyperpolarized gases are administered as inhalative "contrast agents" allowing for imaging of the airways and airspaces. Besides the known anesthetic effect of xenon, no adverse effects are observed in volunteers or patients. Pulse sequences are optimized to effectively use the non-renewable hyperpolarization before it decays or is destroyed, using fast low-flip-angles strategies to allow for dynamic/breath-hold imaging of highly diffusible (He) or soluble (Xe) gases with in vivo T1-times well below 1 min. Since helium is not absorbed in considerable amounts, its application is restricted to the lung. Xe-129 is also under investigation for imaging of white matter disease and functional studies of cerebral perfusion. Magnetic resonance imaging using hyperpolarized gases is emerging as a technical challenge and opportunity for the MR community. Preliminary experience suggests potential for functional imaging of pulmonary ventilation and cerebral perfusion.

Microwave synthesis of gibberellin acid 3 magnetic molecularly imprinted polymer beads for the trace analysis of gibberellin acids in plant samples by liquid chromatography-mass spectrometry detection.

PubMed

Zhang, Zhuomin; Tan, Wei; Hu, Yuling; Li, Gongke; Zan, Song

2012-02-21

In this study, novel GA3 magnetic molecularly imprinted polymer (mag-MIP) beads were synthesized by a microwave irradiation method, and the beads were applied for the trace analysis of gibberellin acids (GAs) in plant samples including rice and cucumber coupled with high performance liquid chromatography-mass spectrometry (HPLC-MS). The microwave synthetic procedure was optimized in detail. In particular, the interaction between GA3 and functional monomers was further studied for the selection of the optimal functional monomers during synthesis. It can be seen that the interaction between GA3 and acrylamide (AM) finally selected was stronger than that between GA3 and other functional monomers. GA3 mag-MIP beads were characterized by a series of physical tests. GA3 mag-MIP beads had a porous and homogeneous surface morphology with stable chemical, thermal and magnetic properties. Moreover, GA3 mag-MIP beads demonstrated selective and specific absorption behavior for the target compounds during unsaturated extraction, which resulted in a higher extraction capacity (∼708.4 pmol for GA3) and selectivity than GA3 mag-non-imprinted polymer beads. Finally, an analytical method of GA3 mag-AM-MIP bead extraction coupled with HPLC-MS detection was established and applied for the determination of trace GA1, GA3, GA4 and GA7 in rice and cucumber samples. It was satisfactory that GA4 could be actually found to be 121.5 ± 1.4 μg kg(-1) in real rice samples by this novel analytical method. The recoveries of spiked rice and cucumber samples were found to be 76.0-109.1% and 79.9-93.6% with RSDs of 2.8-8.8% and 3.1-7.7% (n = 3), respectively. The proposed method is efficient and applicable for the trace analysis of GAs in complicated plant samples.

Teacher's Resource Book for Balloons and Gases. Grade 6. Revised. Anchorage School District Elementary Science Program.

ERIC Educational Resources Information Center

Anchorage School District, AK.

This resource book introduces sixth-grade children to the physical and chemical properties of gases. The unit begins with an investigation of acids and bases. Students then generate carbon dioxide, oxygen, and hydrogen, and investigate the properties of each. The unit culminates with an activity involving an unknown gas. Students conduct tests to…

Investigating African trace gas sources, vertical transport, and oxidation using IAGOS-CARIBIC measurements between Germany and South Africa between 2009 and 2011

NASA Astrophysics Data System (ADS)

Thorenz, U. R.; Baker, A. K.; Leedham Elvidge, E. C.; Sauvage, C.; Riede, H.; van Velthoven, P. F. J.; Hermann, M.; Weigelt, A.; Oram, D. E.; Brenninkmeijer, C. A. M.; Zahn, A.; Williams, J.

2017-06-01

Between March 2009 and March 2011 a commercial airliner equipped with a custom built measurement container (IAGOS-CARIBIC observatory) conducted 13 flights between South Africa and Germany at 10-12 km altitude, traversing the African continent north-south. In-situ measurements of trace gases (CO, CH4, H2O) and aerosol particles indicated that strong surface sources (like biomass burning) and rapid vertical transport combine to generate maximum concentrations in the latitudinal range between 10°N and 10°S coincident with the inter-tropical convergence zone (ITCZ). Pressurized air samples collected during these flights were subsequently analyzed for a suite of trace gases including C2-C8 non-methane hydrocarbons (NMHC) and halocarbons. These shorter-lived trace gases, originating from both natural and anthropogenic sources, also showed near equatorial maxima highlighting the effectiveness of convective transport in this region. Two source apportionment methods were used to investigate the specific sources of NMHC: positive matrix factorization (PMF), which is used for the first time for NMHC analysis in the upper troposphere (UT), and enhancement ratios to CO. Using the PMF method three characteristic airmass types were identified based on the different trace gas concentrations they obtained: biomass burning, fossil fuel emissions, and "background" air. The first two sources were defined with reference to previously reported surface source characterizations, while the term "background" was given to air masses in which the concentration ratios approached that of the lifetime ratios. Comparison of enhancement ratios between NMHC and CO for the subset of air samples that had experienced recent contact with the planetary boundary layer (PBL) to literature values showed that the burning of savanna and tropical forest is likely the main source of NMHC in the African upper troposphere (10-12 km). Photochemical aging patterns for the samples with PBL contact revealed that

Landfill gases and some effects on vegetation

Treesearch

Franklin B. Flower; Ida A. Leone; Edward F. Gilman; John J. Arthur

1977-01-01

Gases moving from refuse landfills through soil were studied in New Jersey. The gases, products of anaerobic decomposition of organic matter in the refuse, caused injury and death of peach trees, ornamentals, and commercial farm crops, and create possible hazards to life and property because of the entrance of combustible gases into residences. Remedial measures are...

Resonant photoacoustic detection of NO2 traces with a Q-switched green laser

NASA Astrophysics Data System (ADS)

Slezak, Verónica; Codnia, Jorge; Peuriot, Alejandro L.; Santiago, Guillermo

2003-01-01

Resonant photoacoustic detection of NO2 traces by means of a high repetition pulsed green laser is presented. The resonator is a cylindrical Pyrex glass cell with a measured Q factor 380 for the first radial mode in air at atmospheric pressure. The system is calibrated with known mixtures in dry air and a minimum detectable volume concentration of 50 parts in 109 is obtained (S/N=1). Its sensitivity allows one to detect and quantify NO2 traces in the exhaust gases of cars. Previously, the analysis of gas adsorption and desorption on the walls and of changes in the sample composition is carried out in order to minimize errors in the determination of NO2 content upon application of the extractive method. The efficiency of catalytic converters of several models of automobiles is studied and the NO2 concentration in samples from exhausts of different types of engine (gasoline, diesel, and methane gas) at idling operation are measured.

Coherent structures and trace gases fluxes and concentrations in and above a heterogeneous spruce forest (Invited)

NASA Astrophysics Data System (ADS)

Foken, T.

2013-12-01

Near the FLUXNET site DE-Bay (Waldstein-Weidenbrunnen) three intensive measuring periods took place in 2007, 2008, and 2011 within the EGER project (ExchanGE processes in mountainous Regions). The main focus of all three experiments was the investigation of turbulent structures and their influence on the energy exchange and trace gas fluxes as well as trace gas reactions. Due to a tornado-like storm event an approximately 300 m long forest edge between a 25 m high spruce forest and a clearing was generated about 150 m south of the DE-Bay site. The investigation of processes at these forest edge was the main issue of the 2011 experiment. A main topic of all experiments was the investigation of the coupling between the atmosphere, the crowns and the trunk space as well as the horizontal coupling. This coupling algorithm is based on the analysis of coherent structures at three levels. While a complete coupling was only observed during daytime, at night well-coupled events were found in connection with low-level jets. The change of inert (CO2) or reactive (O3, NO, NO2, HONO) trace gas concentration could be explained with the coupling situation. It was also found that at the forest edge, coherent structures contribute less to total turbulent flux than within the forest. Accordingly, these coherent motions do not ensure that there is better vertical coupling between the forest stand and the overlying atmosphere at the forest edge. The relative contributions of sweeps and ejections to coherent flux reveal that there might be even larger circulations that cause better ventilation at the forest edge. Ejections dominate during the daytime, whereas sweeps contribute more during nighttime. Thus, there is systematic outflow during the daytime and inflow of fresh air directly at the forest edge during the nighttime. To underline these findings perpendicular to the edge, a mobile measuring system investigated the horizontal gradients of temperature, moisture, radiation, carbon

Fatty acid cosubstrates provide β-oxidation precursors for rhamnolipid biosynthesis in Pseudomonas aeruginosa, as evidenced by isotope tracing and gene expression assays.

PubMed

Zhang, Lin; Veres-Schalnat, Tracey A; Somogyi, Arpad; Pemberton, Jeanne E; Maier, Raina M

2012-12-01

Rhamnolipids have multiple potential applications as "green" surfactants for industry, remediation, and medicine. As a result, they have been intensively investigated to add to our understanding of their biosynthesis and improve yields. Several studies have noted that the addition of a fatty acid cosubstrate increases rhamnolipid yields, but a metabolic explanation has not been offered, partly because biosynthesis studies to date have used sugar or sugar derivatives as the carbon source. The objective of this study was to investigate the role of fatty acid cosubstrates in improving rhamnolipid biosynthesis. A combination of stable isotope tracing and gene expression assays was used to identify lipid precursors and potential lipid metabolic pathways used in rhamnolipid synthesis when fatty acid cosubstrates are present. To this end, we compared the rhamnolipids produced and their yields using either glucose alone or glucose and octadecanoic acid-d(35) as cosubstrates. Using a combination of sugar and fatty acids, the rhamnolipid yield was significantly higher (i.e., doubled) than when glucose was used alone. Two patterns of deuterium incorporation (either 1 or 15 deuterium atoms) in a single Rha-C(10) lipid chain were observed for octadecanoic acid-d(35) treatment, indicating that in the presence of a fatty acid cosubstrate, both de novo fatty acid synthesis and β-oxidation are used to provide lipid precursors for rhamnolipids. Gene expression assays showed a 200- to 600-fold increase in the expression of rhlA and rhlB rhamnolipid biosynthesis genes and a more modest increase of 3- to 4-fold of the fadA β-oxidation pathway gene when octadecanoic acid was present. Taken together, these results suggest that the simultaneous use of de novo fatty acid synthesis and β-oxidation pathways allows for higher production of lipid precursors, resulting in increased rhamnolipid yields.

Improvement and validation of trace gas retrieval from ACAM aircraft observation

NASA Astrophysics Data System (ADS)

Liu, C.; Liu, X.; Kowalewski, M. G.; Janz, S. J.; Gonzalez Abad, G.; Pickering, K. E.; Chance, K.; Lamsal, L. N.

2014-12-01

The ACAM (Airborne Compact Atmospheric Mapper) instrument, flown on board the NASA UC-12 aircraft during the DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) campaigns, was designed to provide remote sensing observations of tropospheric and boundary layer pollutants and help understand some of the most important pollutants that directly affect the health of the population. In this study, slant column densities (SCD) of trace gases (O3, NO2, HCHO) are retrieved from ACAM measurements during the Baltimore-Washington D.C. 2011 campaign by the Basic Optical Absorption Spectroscopy (BOAS) trace gas fitting algorithm using a nonlinear least-squares (NLLS) inversion technique, and then are converted to vertical column densities (VCDs) using the Air Mass Factors (AMF) calculated with the VLIDORT (Vector Linearized Discrete Ordinate Radiative Transfer) model and CMAQ (Community Multi-scale Air Quality) model simulations of trace gas profiles. For surface treatment in the AMF, we use high-resolution MODIS climatological BRDF product (Bidirectional Reflectance Distribution Function) at 470 nm for NO2, and use high-resolution surface albedo derived by combining MODIS and OMI albedo databases for HCHO and O3. We validate ACAM results with coincident ground-based PANDORA, aircraft (P3B) spiral and satellite (OMI) measurements and find out generally good agreement especially for NO2 and O3

Method and apparatus for afterburning flue gases

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

Sikander, A.; Bjorkman, A.; Jonsson, G.

1984-11-13

A method of afterburning flue gases comprises passing impure gases from, for example, an incineration plant such as a destructor, process furnace, crematory furnace or heating boiler, through a burner in an afterburner where through enforced mixture with combustion gas they undergo complete combustion. The combustion gas, depending on the composition of the flue gases, may comprise air or oxygen or either mixed with petroleum gas. In apparatus for implementation of the method, the flue gases and the combustion gas are introduced into a burner which blows the gas mixture into a flame bowl where temperatures in the range ofmore » from 1,500/sup 0/-2,000/sup 0/ C. can be achieved. In one embodiment, the burner produces a conical basket-shaped flame in which the flue gases undergo complete combustion.« less

The production of trace gases by photochemistry and lightning in the early atmosphere

NASA Technical Reports Server (NTRS)

Levine, J. S.; Tennille, G. M.; Towe, K. M.; Khanna, R. K.

1986-01-01

Recent atmospheric calculation suggest that the prebiological atmosphere was most probably composed of nitrogen, carbon dioxide, and water vapor, resulting from volatile outgassing, as opposed to the older view of a strongly reducing early atmosphere composed of methane, ammonia, and hydrogen. Photochemical calculations indicate that methane would have been readily destroyed via reaction with the hydroxyl radical produced from water vapor and that ammonia would have been readily lost via photolysis and rainout. The rapid loss of methane and ammonia, coupled with the absence of a significant source of these gases, suggest that atmospheric methane and ammonia were very short lived, if they were present at all. An early atmosphere of N2, CO2, and H2O is stable and leads to the chemical production of a number of atmospheric species of biological significance, including oxygen, ozone, carbon monoxide, formaldehyde, and hydrogen cyanide. Using a photochemical model of the early atmosphere, the chemical productionof these species over a wide range of atmospheric parameters were investigated. These calculations indicate that early atmospheric levels of O3 were significantly below the levels needed to provide UV shielding. The fate of volcanically emitted sulfur species, e.g., sulfur dioxide and hydrogen sulfide, was investigated in the early atmosphere to assess their UV shielding properties. The photochemical calculations show that these species were of insufficient levels, due in part to their short photochemical lifetimes, to provide UV shielding.

Investigation of the impact of trace elements on anaerobic volatile fatty acid degradation using a fractional factorial experimental design.

PubMed

Jiang, Ying; Zhang, Yue; Banks, Charles; Heaven, Sonia; Longhurst, Philip

2017-11-15

The requirement of trace elements (TE) in anaerobic digestion process is widely documented. However, little is understood regarding the specific requirement of elements and their critical concentrations under different operating conditions such as substrate characterisation and temperature. In this study, a flask batch trial using fractional factorial design is conducted to investigate volatile fatty acids (VFA) anaerobic degradation rate under the influence of the individual and combined effect of six TEs (Co, Ni, Mo, Se, Fe and W). The experiment inoculated with food waste digestate, spiked with sodium acetate and sodium propionate both to 10 g/l. This is followed by the addition of a selection of the six elements in accordance with a 2 6-2 fractional factorial principle. The experiment is conducted in duplicate and the degradation of VFA is regularly monitored. Factorial effect analysis on the experimental results reveals that within these experimental conditions, Se has a key role in promoting the degradation rates of both acetic and propionic acids; Mo and Co are found to have a modest effect on increasing propionic acid degradation rate. It is also revealed that Ni shows some inhibitory effects on VFA degradation, possibly due to its toxicity. Additionally, regression coefficients for the main and second order effects are calculated to establish regression models for VFA degradation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Closure device for lead-acid batteries

DOEpatents

Ledjeff, Konstantin

1983-01-01

A closure device for lead-acid batteries includes a filter of granulated activated carbon treated to be hydrophobic combined with means for preventing explosion of emitted hydrogen and oxygen gas. The explosion prevention means includes a vertical open-end tube within the closure housing for maintaining a liquid level above side wall openings in an adjacent closed end tube. Gases vent from the battery through a nozzle directed inside the closed end tube against an impingement surface to remove acid droplets. The gases then flow through the side wall openings and the liquid level to quench any possible ignition prior to entering the activated carbon filter. A wick in the activated carbon filter conducts condensed liquid back to the closure housing to replenish the liquid level limited by the open-end tube.

Application of cascade lasers to detection of trace gaseous atmospheric pollutants

NASA Astrophysics Data System (ADS)

Miczuga, Marcin; Kopczyński, Krzysztof

2016-12-01

Understanding the impact of gaseous pollutants on the earth's atmosphere, as well as more and more felt by mankind negative effects of its contamination, result in increasing the level of environmental awareness and contribute to the intensification of actions aimed at reducing the emission of harmful gases into the atmosphere. At the same time, the extensive studies are conducted in order to continuously monitor the level of air contamination with harmful gases and the industry compliance with the standards limited the amount of emitted pollutants. Over recent years, there has been increasing use of cascade lasers and multi-pass cells in optical systems detecting the gaseous atmospheric pollutants and measuring the gas concentrations. The paper presents the use of a tunable quantum cascade laser as a source of the IR radiation in an advanced detection system enabling the trace gaseous atmospheric pollutants to be identified. Apart from the laser, the main elements of the system are: a multi-pass cell, an IR detector and a module for control and analysis. Operation of the system is exemplified by measuring the level of the air pollution with ammonia, carbon oxide and nitrous oxide.

Comparison of MP AES and ICP-MS for analysis of principal and selected trace elements in nitric acid digests of sunflower (Helianthus annuus).

PubMed

Karlsson, Stefan; Sjöberg, Viktor; Ogar, Anna

2015-04-01

The use of nitrogen as plasma gas for microwave plasma atomic emission spectroscopy (MP AES) is an interesting development in analytical science since the running cost can be significantly reduced in comparison to the inductively coupled argon plasma. Here, we evaluate the performance of the Agilent 4100 MP AES instrument for the analysis of principal metals (Ca, K, Mg, and Na), lithogenic metals (Al, Fe, and Mn) and selected trace metals (As, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, V, and Zn) in nitric acid plant digests. The digests were prepared by microwave-assisted dissolution of dry plant material from sunflower (Helianthus annuus) in concentrated nitric acid. Comparisons are made with analysis of the same solutions with ICP-MS (Agilent 7500cx) using the octopole reaction system (ORS) in the collision mode for As, Fe, and V. The limits of detection were usually in the low µg L(-1) range and all principal and lithogenic metals were successfully determined with the MP AES and provided almost identical results with the ICP-MS. The same applies for the selected trace metals except for As, Co and Mo where the concentrations were below the detection limit with the MP AES. For successful analysis we recommend that (i) only atom lines are used, (ii) ionization is minimized (e.g. addition of CsNO3) and (iii) the use of internal standards should be considered to resolve spectral interferences. Copyright © 2014 Elsevier B.V. All rights reserved.

Biomass burning emissions of trace gases and particles in marine air at Cape Grim, Tasmania

NASA Astrophysics Data System (ADS)

Lawson, S. J.; Keywood, M. D.; Galbally, I. E.; Gras, J. L.; Cainey, J. M.; Cope, M. E.; Krummel, P. B.; Fraser, P. J.; Steele, L. P.; Bentley, S. T.; Meyer, C. P.; Ristovski, Z.; Goldstein, A. H.

2015-12-01

(ΔO3 / ΔCO 0.001-0.074). A short-lived increase in NMOCs by a factor of 10 corresponded with a large CO enhancement, an increase of the NMOC / CO emission ratio (ER) by a factor of 2-4 and a halving of the BC / CO ratio. Rainfall on Robbins Island was observed by radar during this period which likely resulted in a lower fire combustion efficiency, and higher emission of compounds associated with smouldering. This highlights the importance of relatively minor meteorological events on BB emission ratios. Emission factors (EFs) were derived for a range of trace gases, some never before reported for Australian fires, (including hydrogen, phenol and toluene) using the carbon mass balance method. This provides a unique set of EFs for Australian coastal heathland fires. Methyl halide EFs were higher than EFs reported from other studies in Australia and the Northern Hemisphere which is likely due to high halogen content in vegetation on Robbins Island. This work demonstrates the substantial impact that BB plumes can have on the composition of marine air, and the significant changes that can occur as the plume interacts with terrestrial, aged urban and marine emission sources.

Phosphorus recovery and leaching of trace elements from incinerated sewage sludge ash (ISSA).

PubMed

Fang, Le; Li, Jiang-Shan; Guo, Ming Zhi; Cheeseman, C R; Tsang, Daniel C W; Donatello, Shane; Poon, Chi Sun

2018-02-01

Chemical extraction of phosphorus (P) from incinerated sewage sludge ash (ISSA) is adversely influenced by co-dissolution of metals and metalloids. This study investigated P recovery and leaching of Zn, Cu, Pb, As and Ni from ISSA using inorganic acids (sulphuric acid and nitric acid), organic acids (oxalic acid and citric acid), and chelating agents (ethylenediaminetetraacetic acid (EDTA) and ethylene diamine tetramethylene phosphonate (EDTMP)). The aim of this study was to optimize a leaching process to recover P-leachate with high purity for P fertilizer production. The results show that both organic and inorganic acids extract P-containing phases but organic acids leach more trace elements, particularly Cu, Zn, Pb and As. Sulphuric acid was the most efficient for P recovery and achieved 94% of total extraction under the optimal conditions, which were 2-h reaction with 0.2 mol/L H 2 SO 4 at a liquid-to-solid ratio of 20:1. EDTA extracted only 20% of the available P, but the leachates were contaminated with high levels of trace elements under optimum conditions (3-h reaction with EDTA at 0.02 mol/L, pH 2, and liquid-to-solid ratio of 20:1). Therefore, EDTA was considered an appropriate pre-treatment agent for reducing the total metal/metalloid content in ISSA, which produced negligible changes in the structure of ISSA and reduced contamination during subsequent P extraction using sulphuric acid. Copyright © 2017 Elsevier Ltd. All rights reserved.

Towards a List of Molecules as Potential Biosignature Gases for the Search for Life on Exoplanets

NASA Astrophysics Data System (ADS)

Seager, Sara; Bains, William; Petkowski, Janusz

2015-12-01

Thousands of exoplanets are known to orbit nearby stars. Plans for the next generation of space-based and ground-based telescopes are fueling the anticipation that a precious few habitable planets can be identified in the coming decade. Even more highly anticipated is the chance to find signs of life on these habitable planets by way of biosignature gases. But which gases should we search for? We expand on the search of possible biosignature gases and go beyond those studied so far, which include O2, O3, N2O, and CH4, as well as secondary metabolites: methanethiol (CH3SH), dimethyl sulfide ((CH3)2S), methyl chloride (CH3Cl), and carbonyl sulfide (CSO).We present the results of a project to map the chemical space of life’s metabolic products. We have constructed a systematic survey of all possible stable volatile molecules (up to N=6 non-H atoms), and identified those made by life on Earth. Some (such as methyl chloride) are made by Earth life in sufficiently substantial quantities to be candidate biosignatures in an Earth-like exoplanet’s atmosphere; some, such as stibine (SbH3), are produced only in trace amounts. Some entire categories of molecules are not made by Earth life (such as the silanes); these and other absences from the list of biogenic volatiles point to functional patterns in biochemical space. Such patterns may be different for different biochemistry, and so we cannot rule out any small, stable molecule as a candidate biosignature gas. Our goal is for the community to use the list to study the chemicals that might be potential biosignature gases on exoplanets with atmospheres and surface environments different from Earth’s.